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* [PATCH v14 00/74] Convert page cache to XArray
@ 2018-06-17  1:59 Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 01/74] Update email address Matthew Wilcox
                   ` (74 more replies)
  0 siblings, 75 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

The XArray is a replacement for the radix tree.  For the moment it uses
the same data structures, enabling a gradual replacement.  This patch
set implements the XArray and converts the page cache to use it.

A version of these patches has been running under xfstests for over
48 hours, so I have some confidence in them.  The DAX changes have now
also had a reasonable test outing.  This is based on next-20180615 and
is available as a git tree at
git://git.infradead.org/users/willy/linux-dax.git xarray-20180615

I shall create a git branch from -rc1 and ask for that to be included in
-next.  I'm a little concerned I still have no reviews on some of the
later patches.

Changes since v13:
 - Actually fixed bug in workingset conversion that led to exceptional
   entries not being deleted from the XArray.  Not sure how I dropped
   that patch for v13.  Thanks to David Sterba for noticing.
 - Fixed bug in DAX writeback conversion that failed to wake up waiters.
   Thanks to Ross for testing, and to Dan & Jeff for helping me get a
   setup working to reproduce the problem.
 - Converted the new dax_lock_page / dax_unlock_page functions.
 - Moved XArray test suite entirely into the test_xarray kernel module
   to match other test suites.  It can still be built in userspace as
   part of the radix tree test suite.
 - Changed email address.
 - Moved a few functions into different patches to make the test-suite
   additions more logical.
 - Fixed a bug in XA_BUG_ON (oh the irony) where it evaluated the
   condition twice.
 - Constified xa_head() / xa_parent() / xa_entry() and their _locked
   variants.
 - Moved xa_parent() to xarray.h so it can be used from the workingset code.
 - Call the xarray testsuite from the radix tree test suite to ensure
   that I remember to run both test suites ;-)
 - Added some more tests to the test suite.

Matthew Wilcox (74):
  Update email address
  radix tree test suite: Enable ubsan
  dax: Fix use of zero page
  xarray: Replace exceptional entries
  xarray: Change definition of sibling entries
  xarray: Add definition of struct xarray
  xarray: Define struct xa_node
  xarray: Add documentation
  xarray: Add XArray load operation
  xarray: Add XArray tags
  xarray: Add XArray unconditional store operations
  xarray: Add XArray conditional store operations
  xarray: Add XArray iterators
  xarray: Extract entries from an XArray
  xarray: Destroy an XArray
  xarray: Step through an XArray
  xarray: Add xas_for_each_conflict
  xarray: Add xas_create_range
  xarray: Add MAINTAINERS entry
  page cache: Rearrange address_space
  page cache: Convert hole search to XArray
  page cache: Add and replace pages using the XArray
  page cache: Convert page deletion to XArray
  page cache: Convert find_get_entry to XArray
  page cache: Convert find_get_entries to XArray
  page cache: Convert find_get_pages_range to XArray
  page cache: Convert find_get_pages_contig to XArray
  page cache; Convert find_get_pages_range_tag to XArray
  page cache: Convert find_get_entries_tag to XArray
  page cache: Convert filemap_map_pages to XArray
  radix tree test suite: Convert regression1 to XArray
  page cache: Convert delete_batch to XArray
  page cache: Remove stray radix comment
  page cache: Convert filemap_range_has_page to XArray
  mm: Convert page-writeback to XArray
  mm: Convert workingset to XArray
  mm: Convert truncate to XArray
  mm: Convert add_to_swap_cache to XArray
  mm: Convert delete_from_swap_cache to XArray
  mm: Convert __do_page_cache_readahead to XArray
  mm: Convert page migration to XArray
  mm: Convert huge_memory to XArray
  mm: Convert collapse_shmem to XArray
  mm: Convert khugepaged_scan_shmem to XArray
  mm: Convert is_page_cache_freeable to XArray
  pagevec: Use xa_tag_t
  shmem: Convert shmem_radix_tree_replace to XArray
  shmem: Convert shmem_confirm_swap to XArray
  shmem: Convert find_swap_entry to XArray
  shmem: Convert shmem_add_to_page_cache to XArray
  shmem: Convert shmem_alloc_hugepage to XArray
  shmem: Convert shmem_free_swap to XArray
  shmem: Convert shmem_partial_swap_usage to XArray
  memfd: Convert memfd_wait_for_pins to XArray
  memfd: Convert memfd_tag_pins to XArray
  shmem: Comment fixups
  btrfs: Convert page cache to XArray
  fs: Convert buffer to XArray
  fs: Convert writeback to XArray
  nilfs2: Convert to XArray
  f2fs: Convert to XArray
  dax: Rename some functions
  dax: Hash on XArray instead of mapping
  dax: Convert dax_insert_pfn_mkwrite to XArray
  dax: Convert dax_layout_busy_page to XArray
  dax: Convert __dax_invalidate_entry to XArray
  dax: Convert dax writeback to XArray
  dax: Convert dax_lock_page to XArray
  dax: Convert page fault handlers to XArray
  page cache: Finish XArray conversion
  radix tree: Remove radix_tree_update_node_t
  radix tree: Remove split/join code
  radix tree: Remove radix_tree_maybe_preload_order
  radix tree: Remove radix_tree_clear_tags

 .clang-format                                 |    1 -
 .mailmap                                      |    7 +
 Documentation/core-api/index.rst              |    1 +
 Documentation/core-api/xarray.rst             |  395 ++++
 MAINTAINERS                                   |   17 +-
 arch/powerpc/include/asm/book3s/64/pgtable.h  |    4 +-
 arch/powerpc/include/asm/nohash/64/pgtable.h  |    4 +-
 drivers/gpu/drm/i915/i915_gem.c               |   17 +-
 fs/btrfs/compression.c                        |    6 +-
 fs/btrfs/extent_io.c                          |   12 +-
 fs/buffer.c                                   |   14 +-
 fs/dax.c                                      |  878 ++++-----
 fs/ext4/inode.c                               |    2 +-
 fs/f2fs/data.c                                |    6 +-
 fs/f2fs/dir.c                                 |    2 +-
 fs/f2fs/f2fs.h                                |    2 +-
 fs/f2fs/inline.c                              |    2 +-
 fs/f2fs/node.c                                |    6 +-
 fs/fs-writeback.c                             |   25 +-
 fs/gfs2/aops.c                                |    2 +-
 fs/inode.c                                    |    2 +-
 fs/nfs/blocklayout/blocklayout.c              |    2 +-
 fs/nilfs2/btnode.c                            |   26 +-
 fs/nilfs2/page.c                              |   29 +-
 fs/proc/task_mmu.c                            |    2 +-
 include/linux/fs.h                            |   63 +-
 include/linux/pagemap.h                       |   10 +-
 include/linux/pagevec.h                       |    8 +-
 include/linux/radix-tree.h                    |  136 +-
 include/linux/swap.h                          |   22 +-
 include/linux/swapops.h                       |   19 +-
 include/linux/xarray.h                        | 1047 +++++++++-
 lib/Kconfig.debug                             |    3 +
 lib/Makefile                                  |    3 +-
 lib/idr.c                                     |   66 +-
 lib/radix-tree.c                              |  575 +-----
 lib/test_xarray.c                             |  676 +++++++
 lib/xarray.c                                  | 1753 +++++++++++++++++
 mm/filemap.c                                  |  723 +++----
 mm/huge_memory.c                              |   17 +-
 mm/khugepaged.c                               |  177 +-
 mm/madvise.c                                  |    2 +-
 mm/memcontrol.c                               |    2 +-
 mm/memfd.c                                    |  105 +-
 mm/migrate.c                                  |   48 +-
 mm/mincore.c                                  |    2 +-
 mm/page-writeback.c                           |   72 +-
 mm/readahead.c                                |   10 +-
 mm/shmem.c                                    |  201 +-
 mm/swap.c                                     |    6 +-
 mm/swap_state.c                               |  119 +-
 mm/truncate.c                                 |   27 +-
 mm/vmscan.c                                   |   10 +-
 mm/workingset.c                               |   69 +-
 tools/include/asm-generic/bitops.h            |    1 +
 tools/include/asm-generic/bitops/atomic.h     |    9 -
 tools/include/asm-generic/bitops/non-atomic.h |  109 +
 tools/include/linux/bitmap.h                  |    1 +
 tools/include/linux/kernel.h                  |    1 +
 tools/include/linux/spinlock.h                |   12 +-
 tools/testing/radix-tree/.gitignore           |    1 +
 tools/testing/radix-tree/Makefile             |   16 +-
 tools/testing/radix-tree/benchmark.c          |   91 -
 tools/testing/radix-tree/bitmap.c             |   23 +
 tools/testing/radix-tree/idr-test.c           |    6 +-
 tools/testing/radix-tree/linux/bug.h          |    1 +
 tools/testing/radix-tree/linux/kconfig.h      |    1 +
 tools/testing/radix-tree/linux/kernel.h       |    5 +
 tools/testing/radix-tree/linux/lockdep.h      |   11 +
 tools/testing/radix-tree/linux/radix-tree.h   |    1 -
 tools/testing/radix-tree/linux/rcupdate.h     |    2 +
 tools/testing/radix-tree/linux/xarray.h       |    2 +
 tools/testing/radix-tree/main.c               |   21 +-
 tools/testing/radix-tree/multiorder.c         |  272 +--
 tools/testing/radix-tree/regression1.c        |   58 +-
 tools/testing/radix-tree/regression3.c        |   23 -
 tools/testing/radix-tree/tag_check.c          |   29 -
 tools/testing/radix-tree/test.c               |    8 +-
 tools/testing/radix-tree/test.h               |    1 +
 tools/testing/radix-tree/xarray.c             |   33 +
 80 files changed, 5462 insertions(+), 2711 deletions(-)
 create mode 100644 Documentation/core-api/xarray.rst
 create mode 100644 lib/test_xarray.c
 create mode 100644 lib/xarray.c
 create mode 100644 tools/include/asm-generic/bitops/non-atomic.h
 create mode 100644 tools/testing/radix-tree/bitmap.c
 create mode 100644 tools/testing/radix-tree/linux/kconfig.h
 create mode 100644 tools/testing/radix-tree/linux/lockdep.h
 create mode 100644 tools/testing/radix-tree/linux/xarray.h
 create mode 100644 tools/testing/radix-tree/xarray.c

-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 01/74] Update email address
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 02/74] radix tree test suite: Enable ubsan Matthew Wilcox
                   ` (73 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Redirect some older email addresses that are in the git logs.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 .mailmap               | 7 +++++++
 MAINTAINERS            | 6 +++---
 include/linux/xarray.h | 2 +-
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/.mailmap b/.mailmap
index 29ddeb1bf015..a80dca923d32 100644
--- a/.mailmap
+++ b/.mailmap
@@ -114,6 +114,13 @@ Mark Brown <broonie@sirena.org.uk>
 Mark Yao <markyao0591@gmail.com> <mark.yao@rock-chips.com>
 Martin Kepplinger <martink@posteo.de> <martin.kepplinger@theobroma-systems.com>
 Martin Kepplinger <martink@posteo.de> <martin.kepplinger@ginzinger.com>
+Matthew Wilcox <willy@infradead.org> <matthew.r.wilcox@intel.com>
+Matthew Wilcox <willy@infradead.org> <matthew@wil.cx>
+Matthew Wilcox <willy@infradead.org> <mawilcox@linuxonhyperv.com>
+Matthew Wilcox <willy@infradead.org> <mawilcox@microsoft.com>
+Matthew Wilcox <willy@infradead.org> <willy@debian.org>
+Matthew Wilcox <willy@infradead.org> <willy@linux.intel.com>
+Matthew Wilcox <willy@infradead.org> <willy@parisc-linux.org>
 Matthieu CASTET <castet.matthieu@free.fr>
 Mauro Carvalho Chehab <mchehab@kernel.org> <mchehab@brturbo.com.br>
 Mauro Carvalho Chehab <mchehab@kernel.org> <maurochehab@gmail.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index f15bc83753f5..6dc2c9cb2d7b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -529,7 +529,7 @@ F:	Documentation/hwmon/adt7475
 F:	drivers/hwmon/adt7475.c
 
 ADVANSYS SCSI DRIVER
-M:	Matthew Wilcox <matthew@wil.cx>
+M:	Matthew Wilcox <willy@infradead.org>
 M:	Hannes Reinecke <hare@suse.com>
 L:	linux-scsi@vger.kernel.org
 S:	Maintained
@@ -4268,7 +4268,7 @@ S:	Maintained
 F:	drivers/i2c/busses/i2c-diolan-u2c.c
 
 FILESYSTEM DIRECT ACCESS (DAX)
-M:	Matthew Wilcox <mawilcox@microsoft.com>
+M:	Matthew Wilcox <willy@infradead.org>
 M:	Ross Zwisler <ross.zwisler@linux.intel.com>
 L:	linux-fsdevel@vger.kernel.org
 S:	Supported
@@ -8452,7 +8452,7 @@ F:	drivers/message/fusion/
 F:	drivers/scsi/mpt3sas/
 
 LSILOGIC/SYMBIOS/NCR 53C8XX and 53C1010 PCI-SCSI drivers
-M:	Matthew Wilcox <matthew@wil.cx>
+M:	Matthew Wilcox <willy@infradead.org>
 L:	linux-scsi@vger.kernel.org
 S:	Maintained
 F:	drivers/scsi/sym53c8xx_2/
diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 2dfc8006fe64..9e4c86853fa4 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -4,7 +4,7 @@
 /*
  * eXtensible Arrays
  * Copyright (c) 2017 Microsoft Corporation
- * Author: Matthew Wilcox <mawilcox@microsoft.com>
+ * Author: Matthew Wilcox <willy@infradead.org>
  */
 
 #include <linux/spinlock.h>
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 02/74] radix tree test suite: Enable ubsan
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 01/74] Update email address Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 03/74] dax: Fix use of zero page Matthew Wilcox
                   ` (72 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Add support for the undefined behaviour sanitizer and fix the bugs
that ubsan pointed out.  Nothing major, and all in the test suite,
not the code.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 tools/testing/radix-tree/Makefile |  5 +++--
 tools/testing/radix-tree/main.c   | 20 +++++++++++---------
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/tools/testing/radix-tree/Makefile b/tools/testing/radix-tree/Makefile
index db66f8a0d4be..da030a65d6d6 100644
--- a/tools/testing/radix-tree/Makefile
+++ b/tools/testing/radix-tree/Makefile
@@ -1,7 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
 
-CFLAGS += -I. -I../../include -g -O2 -Wall -D_LGPL_SOURCE -fsanitize=address
-LDFLAGS += -fsanitize=address
+CFLAGS += -I. -I../../include -g -Og -Wall -D_LGPL_SOURCE -fsanitize=address \
+	  -fsanitize=undefined
+LDFLAGS += -fsanitize=address -fsanitize=undefined
 LDLIBS+= -lpthread -lurcu
 TARGETS = main idr-test multiorder
 CORE_OFILES := radix-tree.o idr.o linux.o test.o find_bit.o
diff --git a/tools/testing/radix-tree/main.c b/tools/testing/radix-tree/main.c
index 257f3f8aacaa..584a8732f5ce 100644
--- a/tools/testing/radix-tree/main.c
+++ b/tools/testing/radix-tree/main.c
@@ -27,20 +27,22 @@ void __gang_check(unsigned long middle, long down, long up, int chunk, int hop)
 		item_check_present(&tree, middle + idx);
 	item_check_absent(&tree, middle + up);
 
-	item_gang_check_present(&tree, middle - down,
-			up + down, chunk, hop);
-	item_full_scan(&tree, middle - down, down + up, chunk);
+	if (chunk > 0) {
+		item_gang_check_present(&tree, middle - down, up + down,
+				chunk, hop);
+		item_full_scan(&tree, middle - down, down + up, chunk);
+	}
 	item_kill_tree(&tree);
 }
 
 void gang_check(void)
 {
-	__gang_check(1 << 30, 128, 128, 35, 2);
-	__gang_check(1 << 31, 128, 128, 32, 32);
-	__gang_check(1 << 31, 128, 128, 32, 100);
-	__gang_check(1 << 31, 128, 128, 17, 7);
-	__gang_check(0xffff0000, 0, 65536, 17, 7);
-	__gang_check(0xfffffffe, 1, 1, 17, 7);
+	__gang_check(1UL << 30, 128, 128, 35, 2);
+	__gang_check(1UL << 31, 128, 128, 32, 32);
+	__gang_check(1UL << 31, 128, 128, 32, 100);
+	__gang_check(1UL << 31, 128, 128, 17, 7);
+	__gang_check(0xffff0000UL, 0, 65536, 17, 7);
+	__gang_check(0xfffffffeUL, 1, 1, 17, 7);
 }
 
 void __big_gang_check(void)
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 03/74] dax: Fix use of zero page
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 01/74] Update email address Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 02/74] radix tree test suite: Enable ubsan Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 04/74] xarray: Replace exceptional entries Matthew Wilcox
                   ` (71 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Use my_zero_pfn instead of ZERO_PAGE, and pass the vaddr to it so it
works on MIPS and s390.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
 fs/dax.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 467601a134bc..c7917b46a75b 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1093,21 +1093,12 @@ static vm_fault_t dax_load_hole(struct address_space *mapping, void *entry,
 {
 	struct inode *inode = mapping->host;
 	unsigned long vaddr = vmf->address;
-	vm_fault_t ret = VM_FAULT_NOPAGE;
-	struct page *zero_page;
-	pfn_t pfn;
-
-	zero_page = ZERO_PAGE(0);
-	if (unlikely(!zero_page)) {
-		ret = VM_FAULT_OOM;
-		goto out;
-	}
+	pfn_t pfn = pfn_to_pfn_t(my_zero_pfn(vaddr));
+	vm_fault_t ret;
 
-	pfn = page_to_pfn_t(zero_page);
 	dax_insert_mapping_entry(mapping, vmf, entry, pfn, RADIX_DAX_ZERO_PAGE,
 			false);
 	ret = vmf_insert_mixed(vmf->vma, vaddr, pfn);
-out:
 	trace_dax_load_hole(inode, vmf, ret);
 	return ret;
 }
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 04/74] xarray: Replace exceptional entries
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (2 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 03/74] dax: Fix use of zero page Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 05/74] xarray: Change definition of sibling entries Matthew Wilcox
                   ` (70 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Introduce xarray value entries to replace the radix tree exceptional
entry code.  This is a slight change in encoding to allow the use of an
extra bit (we can now store BITS_PER_LONG - 1 bits in a value entry).
It is also a change in emphasis; exceptional entries are intimidating
and different.  As the comment explains, you can choose to store values
or pointers in the xarray and they are both first-class citizens.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
---
 arch/powerpc/include/asm/book3s/64/pgtable.h |   4 +-
 arch/powerpc/include/asm/nohash/64/pgtable.h |   4 +-
 drivers/gpu/drm/i915/i915_gem.c              |  17 ++-
 fs/btrfs/compression.c                       |   2 +-
 fs/dax.c                                     | 114 +++++++++----------
 fs/proc/task_mmu.c                           |   2 +-
 include/linux/radix-tree.h                   |  36 ++----
 include/linux/swapops.h                      |  19 ++--
 include/linux/xarray.h                       |  54 +++++++++
 lib/idr.c                                    |  60 ++++------
 lib/radix-tree.c                             |  21 ++--
 mm/filemap.c                                 |  10 +-
 mm/khugepaged.c                              |   2 +-
 mm/madvise.c                                 |   2 +-
 mm/memcontrol.c                              |   2 +-
 mm/mincore.c                                 |   2 +-
 mm/readahead.c                               |   2 +-
 mm/shmem.c                                   |  10 +-
 mm/swap.c                                    |   2 +-
 mm/truncate.c                                |  12 +-
 mm/workingset.c                              |  12 +-
 tools/testing/radix-tree/idr-test.c          |   6 +-
 tools/testing/radix-tree/linux/radix-tree.h  |   1 -
 tools/testing/radix-tree/linux/xarray.h      |   2 +
 tools/testing/radix-tree/multiorder.c        |  47 ++++----
 tools/testing/radix-tree/test.c              |   2 +-
 26 files changed, 226 insertions(+), 221 deletions(-)
 create mode 100644 tools/testing/radix-tree/linux/xarray.h

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index 63cee159022b..6b17ddc070fc 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -703,9 +703,7 @@ static inline bool pte_user(pte_t pte)
 	BUILD_BUG_ON(_PAGE_HPTEFLAGS & (0x1f << _PAGE_BIT_SWAP_TYPE)); \
 	BUILD_BUG_ON(_PAGE_HPTEFLAGS & _PAGE_SWP_SOFT_DIRTY);	\
 	} while (0)
-/*
- * on pte we don't need handle RADIX_TREE_EXCEPTIONAL_SHIFT;
- */
+
 #define SWP_TYPE_BITS 5
 #define __swp_type(x)		(((x).val >> _PAGE_BIT_SWAP_TYPE) \
 				& ((1UL << SWP_TYPE_BITS) - 1))
diff --git a/arch/powerpc/include/asm/nohash/64/pgtable.h b/arch/powerpc/include/asm/nohash/64/pgtable.h
index dd0c7236208f..6752636bc457 100644
--- a/arch/powerpc/include/asm/nohash/64/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/64/pgtable.h
@@ -322,9 +322,7 @@ static inline void __ptep_set_access_flags(struct vm_area_struct *vma,
 #define MAX_SWAPFILES_CHECK() do { \
 	BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > SWP_TYPE_BITS); \
 	} while (0)
-/*
- * on pte we don't need handle RADIX_TREE_EXCEPTIONAL_SHIFT;
- */
+
 #define SWP_TYPE_BITS 5
 #define __swp_type(x)		(((x).val >> _PAGE_BIT_SWAP_TYPE) \
 				& ((1UL << SWP_TYPE_BITS) - 1))
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 3704f4c0c2c9..fd56eee4a790 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -5865,7 +5865,8 @@ i915_gem_object_get_sg(struct drm_i915_gem_object *obj,
 	count = __sg_page_count(sg);
 
 	while (idx + count <= n) {
-		unsigned long exception, i;
+		void *entry;
+		unsigned long i;
 		int ret;
 
 		/* If we cannot allocate and insert this entry, or the
@@ -5880,12 +5881,9 @@ i915_gem_object_get_sg(struct drm_i915_gem_object *obj,
 		if (ret && ret != -EEXIST)
 			goto scan;
 
-		exception =
-			RADIX_TREE_EXCEPTIONAL_ENTRY |
-			idx << RADIX_TREE_EXCEPTIONAL_SHIFT;
+		entry = xa_mk_value(idx);
 		for (i = 1; i < count; i++) {
-			ret = radix_tree_insert(&iter->radix, idx + i,
-						(void *)exception);
+			ret = radix_tree_insert(&iter->radix, idx + i, entry);
 			if (ret && ret != -EEXIST)
 				goto scan;
 		}
@@ -5923,15 +5921,14 @@ i915_gem_object_get_sg(struct drm_i915_gem_object *obj,
 	GEM_BUG_ON(!sg);
 
 	/* If this index is in the middle of multi-page sg entry,
-	 * the radixtree will contain an exceptional entry that points
+	 * the radix tree will contain a value entry that points
 	 * to the start of that range. We will return the pointer to
 	 * the base page and the offset of this page within the
 	 * sg entry's range.
 	 */
 	*offset = 0;
-	if (unlikely(radix_tree_exception(sg))) {
-		unsigned long base =
-			(unsigned long)sg >> RADIX_TREE_EXCEPTIONAL_SHIFT;
+	if (unlikely(xa_is_value(sg))) {
+		unsigned long base = xa_to_value(sg);
 
 		sg = radix_tree_lookup(&iter->radix, base);
 		GEM_BUG_ON(!sg);
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index d3e447b45bf7..8db29f791984 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -447,7 +447,7 @@ static noinline int add_ra_bio_pages(struct inode *inode,
 		rcu_read_lock();
 		page = radix_tree_lookup(&mapping->i_pages, pg_index);
 		rcu_read_unlock();
-		if (page && !radix_tree_exceptional_entry(page)) {
+		if (page && !xa_is_value(page)) {
 			misses++;
 			if (misses > 4)
 				break;
diff --git a/fs/dax.c b/fs/dax.c
index c7917b46a75b..704059ecfa88 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -59,56 +59,57 @@ static int __init init_dax_wait_table(void)
 fs_initcall(init_dax_wait_table);
 
 /*
- * We use lowest available bit in exceptional entry for locking, one bit for
- * the entry size (PMD) and two more to tell us if the entry is a zero page or
- * an empty entry that is just used for locking.  In total four special bits.
+ * DAX pagecache entries use XArray value entries so they can't be mistaken
+ * for pages.  We use one bit for locking, one bit for the entry size (PMD)
+ * and two more to tell us if the entry is a zero page or an empty entry that
+ * is just used for locking.  In total four special bits.
  *
  * If the PMD bit isn't set the entry has size PAGE_SIZE, and if the ZERO_PAGE
  * and EMPTY bits aren't set the entry is a normal DAX entry with a filesystem
  * block allocation.
  */
-#define RADIX_DAX_SHIFT		(RADIX_TREE_EXCEPTIONAL_SHIFT + 4)
-#define RADIX_DAX_ENTRY_LOCK	(1 << RADIX_TREE_EXCEPTIONAL_SHIFT)
-#define RADIX_DAX_PMD		(1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1))
-#define RADIX_DAX_ZERO_PAGE	(1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2))
-#define RADIX_DAX_EMPTY		(1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 3))
+#define DAX_SHIFT	(4)
+#define DAX_LOCKED	(1UL << 0)
+#define DAX_PMD		(1UL << 1)
+#define DAX_ZERO_PAGE	(1UL << 2)
+#define DAX_EMPTY	(1UL << 3)
 
 static unsigned long dax_radix_pfn(void *entry)
 {
-	return (unsigned long)entry >> RADIX_DAX_SHIFT;
+	return xa_to_value(entry) >> DAX_SHIFT;
 }
 
 static void *dax_radix_locked_entry(unsigned long pfn, unsigned long flags)
 {
-	return (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | flags |
-			(pfn << RADIX_DAX_SHIFT) | RADIX_DAX_ENTRY_LOCK);
+	return xa_mk_value(flags | ((unsigned long)pfn << DAX_SHIFT) |
+			DAX_LOCKED);
 }
 
 static unsigned int dax_radix_order(void *entry)
 {
-	if ((unsigned long)entry & RADIX_DAX_PMD)
+	if (xa_to_value(entry) & DAX_PMD)
 		return PMD_SHIFT - PAGE_SHIFT;
 	return 0;
 }
 
 static int dax_is_pmd_entry(void *entry)
 {
-	return (unsigned long)entry & RADIX_DAX_PMD;
+	return xa_to_value(entry) & DAX_PMD;
 }
 
 static int dax_is_pte_entry(void *entry)
 {
-	return !((unsigned long)entry & RADIX_DAX_PMD);
+	return !(xa_to_value(entry) & DAX_PMD);
 }
 
 static int dax_is_zero_entry(void *entry)
 {
-	return (unsigned long)entry & RADIX_DAX_ZERO_PAGE;
+	return xa_to_value(entry) & DAX_ZERO_PAGE;
 }
 
 static int dax_is_empty_entry(void *entry)
 {
-	return (unsigned long)entry & RADIX_DAX_EMPTY;
+	return xa_to_value(entry) & DAX_EMPTY;
 }
 
 /*
@@ -186,9 +187,9 @@ static void dax_wake_mapping_entry_waiter(struct address_space *mapping,
  */
 static inline int slot_locked(struct address_space *mapping, void **slot)
 {
-	unsigned long entry = (unsigned long)
-		radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock);
-	return entry & RADIX_DAX_ENTRY_LOCK;
+	unsigned long entry = xa_to_value(
+		radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock));
+	return entry & DAX_LOCKED;
 }
 
 /*
@@ -196,12 +197,11 @@ static inline int slot_locked(struct address_space *mapping, void **slot)
  */
 static inline void *lock_slot(struct address_space *mapping, void **slot)
 {
-	unsigned long entry = (unsigned long)
-		radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock);
-
-	entry |= RADIX_DAX_ENTRY_LOCK;
-	radix_tree_replace_slot(&mapping->i_pages, slot, (void *)entry);
-	return (void *)entry;
+	unsigned long v = xa_to_value(
+		radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock));
+	void *entry = xa_mk_value(v | DAX_LOCKED);
+	radix_tree_replace_slot(&mapping->i_pages, slot, entry);
+	return entry;
 }
 
 /*
@@ -209,17 +209,16 @@ static inline void *lock_slot(struct address_space *mapping, void **slot)
  */
 static inline void *unlock_slot(struct address_space *mapping, void **slot)
 {
-	unsigned long entry = (unsigned long)
-		radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock);
-
-	entry &= ~(unsigned long)RADIX_DAX_ENTRY_LOCK;
-	radix_tree_replace_slot(&mapping->i_pages, slot, (void *)entry);
-	return (void *)entry;
+	unsigned long v = xa_to_value(
+		radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock));
+	void *entry = xa_mk_value(v & ~DAX_LOCKED);
+	radix_tree_replace_slot(&mapping->i_pages, slot, entry);
+	return entry;
 }
 
 /*
  * Lookup entry in radix tree, wait for it to become unlocked if it is
- * exceptional entry and return it. The caller must call
+ * a DAX entry and return it. The caller must call
  * put_unlocked_mapping_entry() when he decided not to lock the entry or
  * put_locked_mapping_entry() when he locked the entry and now wants to
  * unlock it.
@@ -240,7 +239,7 @@ static void *get_unlocked_mapping_entry(struct address_space *mapping,
 		entry = __radix_tree_lookup(&mapping->i_pages, index, NULL,
 					  &slot);
 		if (!entry ||
-		    WARN_ON_ONCE(!radix_tree_exceptional_entry(entry)) ||
+		    WARN_ON_ONCE(!xa_is_value(entry)) ||
 		    !slot_locked(mapping, slot)) {
 			if (slotp)
 				*slotp = slot;
@@ -264,7 +263,7 @@ static void dax_unlock_mapping_entry(struct address_space *mapping,
 
 	xa_lock_irq(&mapping->i_pages);
 	entry = __radix_tree_lookup(&mapping->i_pages, index, NULL, &slot);
-	if (WARN_ON_ONCE(!entry || !radix_tree_exceptional_entry(entry) ||
+	if (WARN_ON_ONCE(!entry || !xa_is_value(entry) ||
 			 !slot_locked(mapping, slot))) {
 		xa_unlock_irq(&mapping->i_pages);
 		return;
@@ -414,8 +413,7 @@ struct page *dax_lock_page(unsigned long pfn)
 
 		entry = __radix_tree_lookup(&mapping->i_pages, index, NULL,
 				&slot);
-		if (!entry ||
-		    WARN_ON_ONCE(!radix_tree_exceptional_entry(entry))) {
+		if (!entry || WARN_ON_ONCE(!xa_is_value(entry))) {
 			xa_unlock_irq(&mapping->i_pages);
 			break;
 		} else if (!slot_locked(mapping, slot)) {
@@ -451,12 +449,11 @@ void dax_unlock_page(struct page *page)
 }
 
 /*
- * Find radix tree entry at given index. If it points to an exceptional entry,
- * return it with the radix tree entry locked. If the radix tree doesn't
- * contain given index, create an empty exceptional entry for the index and
- * return with it locked.
+ * Find radix tree entry at given index. If it is a DAX entry, return it
+ * with the radix tree entry locked. If the radix tree doesn't contain the
+ * given index, create an empty entry for the index and return with it locked.
  *
- * When requesting an entry with size RADIX_DAX_PMD, grab_mapping_entry() will
+ * When requesting an entry with size DAX_PMD, grab_mapping_entry() will
  * either return that locked entry or will return an error.  This error will
  * happen if there are any 4k entries within the 2MiB range that we are
  * requesting.
@@ -486,13 +483,13 @@ static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index,
 	xa_lock_irq(&mapping->i_pages);
 	entry = get_unlocked_mapping_entry(mapping, index, &slot);
 
-	if (WARN_ON_ONCE(entry && !radix_tree_exceptional_entry(entry))) {
+	if (WARN_ON_ONCE(entry && !xa_is_value(entry))) {
 		entry = ERR_PTR(-EIO);
 		goto out_unlock;
 	}
 
 	if (entry) {
-		if (size_flag & RADIX_DAX_PMD) {
+		if (size_flag & DAX_PMD) {
 			if (dax_is_pte_entry(entry)) {
 				put_unlocked_mapping_entry(mapping, index,
 						entry);
@@ -563,7 +560,7 @@ static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index,
 					true);
 		}
 
-		entry = dax_radix_locked_entry(0, size_flag | RADIX_DAX_EMPTY);
+		entry = dax_radix_locked_entry(0, size_flag | DAX_EMPTY);
 
 		err = __radix_tree_insert(&mapping->i_pages, index,
 				dax_radix_order(entry), entry);
@@ -652,7 +649,7 @@ struct page *dax_layout_busy_page(struct address_space *mapping)
 			if (index >= end)
 				break;
 
-			if (!radix_tree_exceptional_entry(pvec_ent))
+			if (!xa_is_value(pvec_ent))
 				continue;
 
 			xa_lock_irq(&mapping->i_pages);
@@ -684,7 +681,7 @@ static int __dax_invalidate_mapping_entry(struct address_space *mapping,
 
 	xa_lock_irq(pages);
 	entry = get_unlocked_mapping_entry(mapping, index, NULL);
-	if (!entry || WARN_ON_ONCE(!radix_tree_exceptional_entry(entry)))
+	if (!entry || WARN_ON_ONCE(!xa_is_value(entry)))
 		goto out;
 	if (!trunc &&
 	    (radix_tree_tag_get(pages, index, PAGECACHE_TAG_DIRTY) ||
@@ -700,8 +697,8 @@ static int __dax_invalidate_mapping_entry(struct address_space *mapping,
 	return ret;
 }
 /*
- * Delete exceptional DAX entry at @index from @mapping. Wait for radix tree
- * entry to get unlocked before deleting it.
+ * Delete DAX entry at @index from @mapping.  Wait for it
+ * to be unlocked before deleting it.
  */
 int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index)
 {
@@ -711,7 +708,7 @@ int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index)
 	 * This gets called from truncate / punch_hole path. As such, the caller
 	 * must hold locks protecting against concurrent modifications of the
 	 * radix tree (usually fs-private i_mmap_sem for writing). Since the
-	 * caller has seen exceptional entry for this index, we better find it
+	 * caller has seen a DAX entry for this index, we better find it
 	 * at that index as well...
 	 */
 	WARN_ON_ONCE(!ret);
@@ -719,7 +716,7 @@ int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index)
 }
 
 /*
- * Invalidate exceptional DAX entry if it is clean.
+ * Invalidate DAX entry if it is clean.
  */
 int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
 				      pgoff_t index)
@@ -774,7 +771,7 @@ static void *dax_insert_mapping_entry(struct address_space *mapping,
 	if (dirty)
 		__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
 
-	if (dax_is_zero_entry(entry) && !(flags & RADIX_DAX_ZERO_PAGE)) {
+	if (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE)) {
 		/* we are replacing a zero page with block mapping */
 		if (dax_is_pmd_entry(entry))
 			unmap_mapping_pages(mapping, index & ~PG_PMD_COLOUR,
@@ -912,13 +909,13 @@ static int dax_writeback_one(struct dax_device *dax_dev,
 	 * A page got tagged dirty in DAX mapping? Something is seriously
 	 * wrong.
 	 */
-	if (WARN_ON(!radix_tree_exceptional_entry(entry)))
+	if (WARN_ON(!xa_is_value(entry)))
 		return -EIO;
 
 	xa_lock_irq(pages);
 	entry2 = get_unlocked_mapping_entry(mapping, index, &slot);
 	/* Entry got punched out / reallocated? */
-	if (!entry2 || WARN_ON_ONCE(!radix_tree_exceptional_entry(entry2)))
+	if (!entry2 || WARN_ON_ONCE(!xa_is_value(entry2)))
 		goto put_unlocked;
 	/*
 	 * Entry got reallocated elsewhere? No need to writeback. We have to
@@ -1096,8 +1093,9 @@ static vm_fault_t dax_load_hole(struct address_space *mapping, void *entry,
 	pfn_t pfn = pfn_to_pfn_t(my_zero_pfn(vaddr));
 	vm_fault_t ret;
 
-	dax_insert_mapping_entry(mapping, vmf, entry, pfn, RADIX_DAX_ZERO_PAGE,
-			false);
+	dax_insert_mapping_entry(mapping, vmf, entry, pfn,
+			DAX_ZERO_PAGE, false);
+
 	ret = vmf_insert_mixed(vmf->vma, vaddr, pfn);
 	trace_dax_load_hole(inode, vmf, ret);
 	return ret;
@@ -1490,7 +1488,7 @@ static vm_fault_t dax_pmd_load_hole(struct vm_fault *vmf, struct iomap *iomap,
 
 	pfn = page_to_pfn_t(zero_page);
 	ret = dax_insert_mapping_entry(mapping, vmf, entry, pfn,
-			RADIX_DAX_PMD | RADIX_DAX_ZERO_PAGE, false);
+			DAX_PMD | DAX_ZERO_PAGE, false);
 
 	ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
 	if (!pmd_none(*(vmf->pmd))) {
@@ -1573,7 +1571,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	 * is already in the tree, for instance), it will return -EEXIST and
 	 * we just fall back to 4k entries.
 	 */
-	entry = grab_mapping_entry(mapping, pgoff, RADIX_DAX_PMD);
+	entry = grab_mapping_entry(mapping, pgoff, DAX_PMD);
 	if (IS_ERR(entry))
 		goto fallback;
 
@@ -1611,7 +1609,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 			goto finish_iomap;
 
 		entry = dax_insert_mapping_entry(mapping, vmf, entry, pfn,
-						RADIX_DAX_PMD, write && !sync);
+						DAX_PMD, write && !sync);
 
 		/*
 		 * If we are doing synchronous page fault and inode needs fsync,
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index e9679016271f..bfafafa94a84 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -553,7 +553,7 @@ static void smaps_pte_entry(pte_t *pte, unsigned long addr,
 		if (!page)
 			return;
 
-		if (radix_tree_exceptional_entry(page))
+		if (xa_is_value(page))
 			mss->swap += PAGE_SIZE;
 		else
 			put_page(page);
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 34149e8b5f73..87f35fe00e55 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -28,34 +28,26 @@
 #include <linux/rcupdate.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
+#include <linux/xarray.h>
 
 /*
  * The bottom two bits of the slot determine how the remaining bits in the
  * slot are interpreted:
  *
  * 00 - data pointer
- * 01 - internal entry
- * 10 - exceptional entry
- * 11 - this bit combination is currently unused/reserved
+ * 10 - internal entry
+ * x1 - value entry
  *
  * The internal entry may be a pointer to the next level in the tree, a
  * sibling entry, or an indicator that the entry in this slot has been moved
  * to another location in the tree and the lookup should be restarted.  While
  * NULL fits the 'data pointer' pattern, it means that there is no entry in
  * the tree for this index (no matter what level of the tree it is found at).
- * This means that you cannot store NULL in the tree as a value for the index.
+ * This means that storing a NULL entry in the tree is the same as deleting
+ * the entry from the tree.
  */
 #define RADIX_TREE_ENTRY_MASK		3UL
-#define RADIX_TREE_INTERNAL_NODE	1UL
-
-/*
- * Most users of the radix tree store pointers but shmem/tmpfs stores swap
- * entries in the same tree.  They are marked as exceptional entries to
- * distinguish them from pointers to struct page.
- * EXCEPTIONAL_ENTRY tests the bit, EXCEPTIONAL_SHIFT shifts content past it.
- */
-#define RADIX_TREE_EXCEPTIONAL_ENTRY	2
-#define RADIX_TREE_EXCEPTIONAL_SHIFT	2
+#define RADIX_TREE_INTERNAL_NODE	2UL
 
 static inline bool radix_tree_is_internal_node(void *ptr)
 {
@@ -83,11 +75,10 @@ static inline bool radix_tree_is_internal_node(void *ptr)
 
 /*
  * @count is the count of every non-NULL element in the ->slots array
- * whether that is an exceptional entry, a retry entry, a user pointer,
+ * whether that is a data entry, a retry entry, a user pointer,
  * a sibling entry or a pointer to the next level of the tree.
  * @exceptional is the count of every element in ->slots which is
- * either radix_tree_exceptional_entry() or is a sibling entry for an
- * exceptional entry.
+ * either a data entry or a sibling entry for data.
  */
 struct radix_tree_node {
 	unsigned char	shift;		/* Bits remaining in each slot */
@@ -268,17 +259,6 @@ static inline int radix_tree_deref_retry(void *arg)
 	return unlikely(radix_tree_is_internal_node(arg));
 }
 
-/**
- * radix_tree_exceptional_entry	- radix_tree_deref_slot gave exceptional entry?
- * @arg:	value returned by radix_tree_deref_slot
- * Returns:	0 if well-aligned pointer, non-0 if exceptional entry.
- */
-static inline int radix_tree_exceptional_entry(void *arg)
-{
-	/* Not unlikely because radix_tree_exception often tested first */
-	return (unsigned long)arg & RADIX_TREE_EXCEPTIONAL_ENTRY;
-}
-
 /**
  * radix_tree_exception	- radix_tree_deref_slot returned either exception?
  * @arg:	value returned by radix_tree_deref_slot
diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 1d3877c39a00..9c0eb4d4f444 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -17,9 +17,8 @@
  *
  * swp_entry_t's are *never* stored anywhere in their arch-dependent format.
  */
-#define SWP_TYPE_SHIFT(e)	((sizeof(e.val) * 8) - \
-			(MAX_SWAPFILES_SHIFT + RADIX_TREE_EXCEPTIONAL_SHIFT))
-#define SWP_OFFSET_MASK(e)	((1UL << SWP_TYPE_SHIFT(e)) - 1)
+#define SWP_TYPE_SHIFT	(BITS_PER_XA_VALUE - MAX_SWAPFILES_SHIFT)
+#define SWP_OFFSET_MASK	((1UL << SWP_TYPE_SHIFT) - 1)
 
 /*
  * Store a type+offset into a swp_entry_t in an arch-independent format
@@ -28,8 +27,7 @@ static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
 {
 	swp_entry_t ret;
 
-	ret.val = (type << SWP_TYPE_SHIFT(ret)) |
-			(offset & SWP_OFFSET_MASK(ret));
+	ret.val = (type << SWP_TYPE_SHIFT) | (offset & SWP_OFFSET_MASK);
 	return ret;
 }
 
@@ -39,7 +37,7 @@ static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
  */
 static inline unsigned swp_type(swp_entry_t entry)
 {
-	return (entry.val >> SWP_TYPE_SHIFT(entry));
+	return (entry.val >> SWP_TYPE_SHIFT);
 }
 
 /*
@@ -48,7 +46,7 @@ static inline unsigned swp_type(swp_entry_t entry)
  */
 static inline pgoff_t swp_offset(swp_entry_t entry)
 {
-	return entry.val & SWP_OFFSET_MASK(entry);
+	return entry.val & SWP_OFFSET_MASK;
 }
 
 #ifdef CONFIG_MMU
@@ -89,16 +87,13 @@ static inline swp_entry_t radix_to_swp_entry(void *arg)
 {
 	swp_entry_t entry;
 
-	entry.val = (unsigned long)arg >> RADIX_TREE_EXCEPTIONAL_SHIFT;
+	entry.val = xa_to_value(arg);
 	return entry;
 }
 
 static inline void *swp_to_radix_entry(swp_entry_t entry)
 {
-	unsigned long value;
-
-	value = entry.val << RADIX_TREE_EXCEPTIONAL_SHIFT;
-	return (void *)(value | RADIX_TREE_EXCEPTIONAL_ENTRY);
+	return xa_mk_value(entry.val);
 }
 
 #if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 9e4c86853fa4..e6ead6c81458 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -5,9 +5,63 @@
  * eXtensible Arrays
  * Copyright (c) 2017 Microsoft Corporation
  * Author: Matthew Wilcox <willy@infradead.org>
+ *
+ * See Documentation/core-api/xarray.rst for how to use the XArray.
  */
 
+#include <linux/bug.h>
 #include <linux/spinlock.h>
+#include <linux/types.h>
+
+/*
+ * The bottom two bits of the entry determine how the XArray interprets
+ * the contents:
+ *
+ * 00: Pointer entry
+ * 10: Internal entry
+ * x1: Value entry
+ *
+ * Attempting to store internal entries in the XArray is a bug.
+ */
+
+#define BITS_PER_XA_VALUE	(BITS_PER_LONG - 1)
+
+/**
+ * xa_mk_value() - Create an XArray entry from an integer.
+ * @v: Value to store in XArray.
+ *
+ * Context: Any context.
+ * Return: An entry suitable for storing in the XArray.
+ */
+static inline void *xa_mk_value(unsigned long v)
+{
+	WARN_ON((long)v < 0);
+	return (void *)((v << 1) | 1);
+}
+
+/**
+ * xa_to_value() - Get value stored in an XArray entry.
+ * @entry: XArray entry.
+ *
+ * Context: Any context.
+ * Return: The value stored in the XArray entry.
+ */
+static inline unsigned long xa_to_value(const void *entry)
+{
+	return (unsigned long)entry >> 1;
+}
+
+/**
+ * xa_is_value() - Determine if an entry is a value.
+ * @entry: XArray entry.
+ *
+ * Context: Any context.
+ * Return: True if the entry is a value, false if it is a pointer.
+ */
+static inline bool xa_is_value(const void *entry)
+{
+	return (unsigned long)entry & 1;
+}
 
 #define xa_trylock(xa)		spin_trylock(&(xa)->xa_lock)
 #define xa_lock(xa)		spin_lock(&(xa)->xa_lock)
diff --git a/lib/idr.c b/lib/idr.c
index ed9c169c12bd..3bdcb32760e3 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -348,11 +348,8 @@ EXPORT_SYMBOL(idr_replace);
  * by the number of bits in the leaf bitmap before doing a radix tree lookup.
  *
  * As an optimisation, if there are only a few low bits set in any given
- * leaf, instead of allocating a 128-byte bitmap, we use the 'exceptional
- * entry' functionality of the radix tree to store BITS_PER_LONG - 2 bits
- * directly in the entry.  By being really tricksy, we could store
- * BITS_PER_LONG - 1 bits, but there're diminishing returns after optimising
- * for 0-3 allocated IDs.
+ * leaf, instead of allocating a 128-byte bitmap, we store the bits
+ * directly in the entry.
  *
  * We allow the radix tree 'exceptional' count to get out of date.  Nothing
  * in the IDA nor the radix tree code checks it.  If it becomes important
@@ -394,12 +391,11 @@ int ida_get_new_above(struct ida *ida, int start, int *id)
 	struct radix_tree_iter iter;
 	struct ida_bitmap *bitmap;
 	unsigned long index;
-	unsigned bit, ebit;
+	unsigned bit;
 	int new;
 
 	index = start / IDA_BITMAP_BITS;
 	bit = start % IDA_BITMAP_BITS;
-	ebit = bit + RADIX_TREE_EXCEPTIONAL_SHIFT;
 
 	slot = radix_tree_iter_init(&iter, index);
 	for (;;) {
@@ -414,25 +410,24 @@ int ida_get_new_above(struct ida *ida, int start, int *id)
 				return PTR_ERR(slot);
 			}
 		}
-		if (iter.index > index) {
+		if (iter.index > index)
 			bit = 0;
-			ebit = RADIX_TREE_EXCEPTIONAL_SHIFT;
-		}
 		new = iter.index * IDA_BITMAP_BITS;
 		bitmap = rcu_dereference_raw(*slot);
-		if (radix_tree_exception(bitmap)) {
-			unsigned long tmp = (unsigned long)bitmap;
-			ebit = find_next_zero_bit(&tmp, BITS_PER_LONG, ebit);
-			if (ebit < BITS_PER_LONG) {
-				tmp |= 1UL << ebit;
-				rcu_assign_pointer(*slot, (void *)tmp);
-				*id = new + ebit - RADIX_TREE_EXCEPTIONAL_SHIFT;
+		if (xa_is_value(bitmap)) {
+			unsigned long tmp = xa_to_value(bitmap);
+			int vbit = find_next_zero_bit(&tmp, BITS_PER_XA_VALUE,
+							bit);
+			if (vbit < BITS_PER_XA_VALUE) {
+				tmp |= 1UL << vbit;
+				rcu_assign_pointer(*slot, xa_mk_value(tmp));
+				*id = new + vbit;
 				return 0;
 			}
 			bitmap = this_cpu_xchg(ida_bitmap, NULL);
 			if (!bitmap)
 				return -EAGAIN;
-			bitmap->bitmap[0] = tmp >> RADIX_TREE_EXCEPTIONAL_SHIFT;
+			bitmap->bitmap[0] = tmp;
 			rcu_assign_pointer(*slot, bitmap);
 		}
 
@@ -453,18 +448,14 @@ int ida_get_new_above(struct ida *ida, int start, int *id)
 			new += bit;
 			if (new < 0)
 				return -ENOSPC;
-			if (ebit < BITS_PER_LONG) {
-				bitmap = (void *)((1UL << ebit) |
-						RADIX_TREE_EXCEPTIONAL_ENTRY);
-				radix_tree_iter_replace(root, &iter, slot,
-						bitmap);
-				*id = new;
-				return 0;
+			if (bit < BITS_PER_XA_VALUE) {
+				bitmap = xa_mk_value(1UL << bit);
+			} else {
+				bitmap = this_cpu_xchg(ida_bitmap, NULL);
+				if (!bitmap)
+					return -EAGAIN;
+				__set_bit(bit, bitmap->bitmap);
 			}
-			bitmap = this_cpu_xchg(ida_bitmap, NULL);
-			if (!bitmap)
-				return -EAGAIN;
-			__set_bit(bit, bitmap->bitmap);
 			radix_tree_iter_replace(root, &iter, slot, bitmap);
 		}
 
@@ -495,9 +486,9 @@ void ida_remove(struct ida *ida, int id)
 		goto err;
 
 	bitmap = rcu_dereference_raw(*slot);
-	if (radix_tree_exception(bitmap)) {
+	if (xa_is_value(bitmap)) {
 		btmp = (unsigned long *)slot;
-		offset += RADIX_TREE_EXCEPTIONAL_SHIFT;
+		offset += 1; /* Intimate knowledge of the xa_data encoding */
 		if (offset >= BITS_PER_LONG)
 			goto err;
 	} else {
@@ -508,9 +499,8 @@ void ida_remove(struct ida *ida, int id)
 
 	__clear_bit(offset, btmp);
 	radix_tree_iter_tag_set(&ida->ida_rt, &iter, IDR_FREE);
-	if (radix_tree_exception(bitmap)) {
-		if (rcu_dereference_raw(*slot) ==
-					(void *)RADIX_TREE_EXCEPTIONAL_ENTRY)
+	if (xa_is_value(bitmap)) {
+		if (xa_to_value(rcu_dereference_raw(*slot)) == 0)
 			radix_tree_iter_delete(&ida->ida_rt, &iter, slot);
 	} else if (bitmap_empty(btmp, IDA_BITMAP_BITS)) {
 		kfree(bitmap);
@@ -538,7 +528,7 @@ void ida_destroy(struct ida *ida)
 
 	radix_tree_for_each_slot(slot, &ida->ida_rt, &iter, 0) {
 		struct ida_bitmap *bitmap = rcu_dereference_raw(*slot);
-		if (!radix_tree_exception(bitmap))
+		if (!xa_is_value(bitmap))
 			kfree(bitmap);
 		radix_tree_iter_delete(&ida->ida_rt, &iter, slot);
 	}
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index a9e41aed6de4..fa43dcdc1f6a 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -340,14 +340,12 @@ static void dump_ida_node(void *entry, unsigned long index)
 		for (i = 0; i < RADIX_TREE_MAP_SIZE; i++)
 			dump_ida_node(node->slots[i],
 					index | (i << node->shift));
-	} else if (radix_tree_exceptional_entry(entry)) {
+	} else if (xa_is_value(entry)) {
 		pr_debug("ida excp: %p offset %d indices %lu-%lu data %lx\n",
 				entry, (int)(index & RADIX_TREE_MAP_MASK),
 				index * IDA_BITMAP_BITS,
-				index * IDA_BITMAP_BITS + BITS_PER_LONG -
-					RADIX_TREE_EXCEPTIONAL_SHIFT,
-				(unsigned long)entry >>
-					RADIX_TREE_EXCEPTIONAL_SHIFT);
+				index * IDA_BITMAP_BITS + BITS_PER_XA_VALUE,
+				xa_to_value(entry));
 	} else {
 		struct ida_bitmap *bitmap = entry;
 
@@ -656,7 +654,7 @@ static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp,
 		BUG_ON(shift > BITS_PER_LONG);
 		if (radix_tree_is_internal_node(entry)) {
 			entry_to_node(entry)->parent = node;
-		} else if (radix_tree_exceptional_entry(entry)) {
+		} else if (xa_is_value(entry)) {
 			/* Moving an exceptional root->rnode to a node */
 			node->exceptional = 1;
 		}
@@ -947,12 +945,12 @@ static inline int insert_entries(struct radix_tree_node *node,
 					!is_sibling_entry(node, old) &&
 					(old != RADIX_TREE_RETRY))
 			radix_tree_free_nodes(old);
-		if (radix_tree_exceptional_entry(old))
+		if (xa_is_value(old))
 			node->exceptional--;
 	}
 	if (node) {
 		node->count += n;
-		if (radix_tree_exceptional_entry(item))
+		if (xa_is_value(item))
 			node->exceptional += n;
 	}
 	return n;
@@ -966,7 +964,7 @@ static inline int insert_entries(struct radix_tree_node *node,
 	rcu_assign_pointer(*slot, item);
 	if (node) {
 		node->count++;
-		if (radix_tree_exceptional_entry(item))
+		if (xa_is_value(item))
 			node->exceptional++;
 	}
 	return 1;
@@ -1183,8 +1181,7 @@ void __radix_tree_replace(struct radix_tree_root *root,
 			  radix_tree_update_node_t update_node)
 {
 	void *old = rcu_dereference_raw(*slot);
-	int exceptional = !!radix_tree_exceptional_entry(item) -
-				!!radix_tree_exceptional_entry(old);
+	int exceptional = !!xa_is_value(item) - !!xa_is_value(old);
 	int count = calculate_count(root, node, slot, item, old);
 
 	/*
@@ -1985,7 +1982,7 @@ static bool __radix_tree_delete(struct radix_tree_root *root,
 				struct radix_tree_node *node, void __rcu **slot)
 {
 	void *old = rcu_dereference_raw(*slot);
-	int exceptional = radix_tree_exceptional_entry(old) ? -1 : 0;
+	int exceptional = xa_is_value(old) ? -1 : 0;
 	unsigned offset = get_slot_offset(node, slot);
 	int tag;
 
diff --git a/mm/filemap.c b/mm/filemap.c
index 52517f28e6f4..4de14e75c4ec 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -127,7 +127,7 @@ static int page_cache_tree_insert(struct address_space *mapping,
 
 		p = radix_tree_deref_slot_protected(slot,
 						    &mapping->i_pages.xa_lock);
-		if (!radix_tree_exceptional_entry(p))
+		if (!xa_is_value(p))
 			return -EEXIST;
 
 		mapping->nrexceptional--;
@@ -336,7 +336,7 @@ page_cache_tree_delete_batch(struct address_space *mapping,
 			break;
 		page = radix_tree_deref_slot_protected(slot,
 						       &mapping->i_pages.xa_lock);
-		if (radix_tree_exceptional_entry(page))
+		if (xa_is_value(page))
 			continue;
 		if (!tail_pages) {
 			/*
@@ -1355,7 +1355,7 @@ pgoff_t page_cache_next_hole(struct address_space *mapping,
 		struct page *page;
 
 		page = radix_tree_lookup(&mapping->i_pages, index);
-		if (!page || radix_tree_exceptional_entry(page))
+		if (!page || xa_is_value(page))
 			break;
 		index++;
 		if (index == 0)
@@ -1396,7 +1396,7 @@ pgoff_t page_cache_prev_hole(struct address_space *mapping,
 		struct page *page;
 
 		page = radix_tree_lookup(&mapping->i_pages, index);
-		if (!page || radix_tree_exceptional_entry(page))
+		if (!page || xa_is_value(page))
 			break;
 		index--;
 		if (index == ULONG_MAX)
@@ -1539,7 +1539,7 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
 
 repeat:
 	page = find_get_entry(mapping, offset);
-	if (radix_tree_exceptional_entry(page))
+	if (xa_is_value(page))
 		page = NULL;
 	if (!page)
 		goto no_page;
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index d7b2a4bf8671..d6992ba1f604 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1368,7 +1368,7 @@ static void collapse_shmem(struct mm_struct *mm,
 
 		page = radix_tree_deref_slot_protected(slot,
 				&mapping->i_pages.xa_lock);
-		if (radix_tree_exceptional_entry(page) || !PageUptodate(page)) {
+		if (xa_is_value(page) || !PageUptodate(page)) {
 			xa_unlock_irq(&mapping->i_pages);
 			/* swap in or instantiate fallocated page */
 			if (shmem_getpage(mapping->host, index, &page,
diff --git a/mm/madvise.c b/mm/madvise.c
index b731933dddae..6ed8cfe7f6de 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -251,7 +251,7 @@ static void force_shm_swapin_readahead(struct vm_area_struct *vma,
 		index = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
 
 		page = find_get_entry(mapping, index);
-		if (!radix_tree_exceptional_entry(page)) {
+		if (!xa_is_value(page)) {
 			if (page)
 				put_page(page);
 			continue;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 02e77c88967a..c3b5ba593e69 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4682,7 +4682,7 @@ static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
 	/* shmem/tmpfs may report page out on swap: account for that too. */
 	if (shmem_mapping(mapping)) {
 		page = find_get_entry(mapping, pgoff);
-		if (radix_tree_exceptional_entry(page)) {
+		if (xa_is_value(page)) {
 			swp_entry_t swp = radix_to_swp_entry(page);
 			if (do_memsw_account())
 				*entry = swp;
diff --git a/mm/mincore.c b/mm/mincore.c
index a66f2052c7b1..aa0e542569f9 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -66,7 +66,7 @@ static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
 		 * shmem/tmpfs may return swap: account for swapcache
 		 * page too.
 		 */
-		if (radix_tree_exceptional_entry(page)) {
+		if (xa_is_value(page)) {
 			swp_entry_t swp = radix_to_swp_entry(page);
 			struct swap_info_struct *si;
 
diff --git a/mm/readahead.c b/mm/readahead.c
index e273f0de3376..3757aa549709 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -177,7 +177,7 @@ unsigned int __do_page_cache_readahead(struct address_space *mapping,
 		rcu_read_lock();
 		page = radix_tree_lookup(&mapping->i_pages, page_offset);
 		rcu_read_unlock();
-		if (page && !radix_tree_exceptional_entry(page)) {
+		if (page && !xa_is_value(page)) {
 			/*
 			 * Page already present?  Kick off the current batch of
 			 * contiguous pages before continuing with the next
diff --git a/mm/shmem.c b/mm/shmem.c
index 2cab84403055..3b03ede3515c 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -708,7 +708,7 @@ unsigned long shmem_partial_swap_usage(struct address_space *mapping,
 			continue;
 		}
 
-		if (radix_tree_exceptional_entry(page))
+		if (xa_is_value(page))
 			swapped++;
 
 		if (need_resched()) {
@@ -823,7 +823,7 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 			if (index >= end)
 				break;
 
-			if (radix_tree_exceptional_entry(page)) {
+			if (xa_is_value(page)) {
 				if (unfalloc)
 					continue;
 				nr_swaps_freed += !shmem_free_swap(mapping,
@@ -920,7 +920,7 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 			if (index >= end)
 				break;
 
-			if (radix_tree_exceptional_entry(page)) {
+			if (xa_is_value(page)) {
 				if (unfalloc)
 					continue;
 				if (shmem_free_swap(mapping, index, page)) {
@@ -1641,7 +1641,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
 repeat:
 	swap.val = 0;
 	page = find_lock_entry(mapping, index);
-	if (radix_tree_exceptional_entry(page)) {
+	if (xa_is_value(page)) {
 		swap = radix_to_swp_entry(page);
 		page = NULL;
 	}
@@ -2574,7 +2574,7 @@ static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
 				index = indices[i];
 			}
 			page = pvec.pages[i];
-			if (page && !radix_tree_exceptional_entry(page)) {
+			if (page && !xa_is_value(page)) {
 				if (!PageUptodate(page))
 					page = NULL;
 			}
diff --git a/mm/swap.c b/mm/swap.c
index 26fc9b5f1b6c..4c5c7fcc6e46 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -965,7 +965,7 @@ void pagevec_remove_exceptionals(struct pagevec *pvec)
 
 	for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
 		struct page *page = pvec->pages[i];
-		if (!radix_tree_exceptional_entry(page))
+		if (!xa_is_value(page))
 			pvec->pages[j++] = page;
 	}
 	pvec->nr = j;
diff --git a/mm/truncate.c b/mm/truncate.c
index 1d2fb2dca96f..ed778555c9f3 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -70,7 +70,7 @@ static void truncate_exceptional_pvec_entries(struct address_space *mapping,
 		return;
 
 	for (j = 0; j < pagevec_count(pvec); j++)
-		if (radix_tree_exceptional_entry(pvec->pages[j]))
+		if (xa_is_value(pvec->pages[j]))
 			break;
 
 	if (j == pagevec_count(pvec))
@@ -85,7 +85,7 @@ static void truncate_exceptional_pvec_entries(struct address_space *mapping,
 		struct page *page = pvec->pages[i];
 		pgoff_t index = indices[i];
 
-		if (!radix_tree_exceptional_entry(page)) {
+		if (!xa_is_value(page)) {
 			pvec->pages[j++] = page;
 			continue;
 		}
@@ -347,7 +347,7 @@ void truncate_inode_pages_range(struct address_space *mapping,
 			if (index >= end)
 				break;
 
-			if (radix_tree_exceptional_entry(page))
+			if (xa_is_value(page))
 				continue;
 
 			if (!trylock_page(page))
@@ -442,7 +442,7 @@ void truncate_inode_pages_range(struct address_space *mapping,
 				break;
 			}
 
-			if (radix_tree_exceptional_entry(page))
+			if (xa_is_value(page))
 				continue;
 
 			lock_page(page);
@@ -561,7 +561,7 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping,
 			if (index > end)
 				break;
 
-			if (radix_tree_exceptional_entry(page)) {
+			if (xa_is_value(page)) {
 				invalidate_exceptional_entry(mapping, index,
 							     page);
 				continue;
@@ -692,7 +692,7 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
 			if (index > end)
 				break;
 
-			if (radix_tree_exceptional_entry(page)) {
+			if (xa_is_value(page)) {
 				if (!invalidate_exceptional_entry2(mapping,
 								   index, page))
 					ret = -EBUSY;
diff --git a/mm/workingset.c b/mm/workingset.c
index 40ee02c83978..b5dd3936e697 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -155,8 +155,8 @@
  * refault distance will immediately activate the refaulting page.
  */
 
-#define EVICTION_SHIFT	(RADIX_TREE_EXCEPTIONAL_ENTRY + \
-			 NODES_SHIFT +	\
+#define EVICTION_SHIFT	((BITS_PER_LONG - BITS_PER_XA_VALUE) +	\
+			 NODES_SHIFT +				\
 			 MEM_CGROUP_ID_SHIFT)
 #define EVICTION_MASK	(~0UL >> EVICTION_SHIFT)
 
@@ -175,18 +175,16 @@ static void *pack_shadow(int memcgid, pg_data_t *pgdat, unsigned long eviction)
 	eviction >>= bucket_order;
 	eviction = (eviction << MEM_CGROUP_ID_SHIFT) | memcgid;
 	eviction = (eviction << NODES_SHIFT) | pgdat->node_id;
-	eviction = (eviction << RADIX_TREE_EXCEPTIONAL_SHIFT);
 
-	return (void *)(eviction | RADIX_TREE_EXCEPTIONAL_ENTRY);
+	return xa_mk_value(eviction);
 }
 
 static void unpack_shadow(void *shadow, int *memcgidp, pg_data_t **pgdat,
 			  unsigned long *evictionp)
 {
-	unsigned long entry = (unsigned long)shadow;
+	unsigned long entry = xa_to_value(shadow);
 	int memcgid, nid;
 
-	entry >>= RADIX_TREE_EXCEPTIONAL_SHIFT;
 	nid = entry & ((1UL << NODES_SHIFT) - 1);
 	entry >>= NODES_SHIFT;
 	memcgid = entry & ((1UL << MEM_CGROUP_ID_SHIFT) - 1);
@@ -453,7 +451,7 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
 		goto out_invalid;
 	for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
 		if (node->slots[i]) {
-			if (WARN_ON_ONCE(!radix_tree_exceptional_entry(node->slots[i])))
+			if (WARN_ON_ONCE(!xa_is_value(node->slots[i])))
 				goto out_invalid;
 			if (WARN_ON_ONCE(!node->exceptional))
 				goto out_invalid;
diff --git a/tools/testing/radix-tree/idr-test.c b/tools/testing/radix-tree/idr-test.c
index ee820fcc29b0..46fc2f1142c3 100644
--- a/tools/testing/radix-tree/idr-test.c
+++ b/tools/testing/radix-tree/idr-test.c
@@ -19,7 +19,7 @@
 
 #include "test.h"
 
-#define DUMMY_PTR	((void *)0x12)
+#define DUMMY_PTR	((void *)0x10)
 
 int item_idr_free(int id, void *p, void *data)
 {
@@ -400,11 +400,11 @@ void ida_check_conv(void)
 	for (i = 0; i < 1000000; i++) {
 		int err = ida_get_new(&ida, &id);
 		if (err == -EAGAIN) {
-			assert((i % IDA_BITMAP_BITS) == (BITS_PER_LONG - 2));
+			assert((i % IDA_BITMAP_BITS) == BITS_PER_XA_VALUE);
 			assert(ida_pre_get(&ida, GFP_KERNEL));
 			err = ida_get_new(&ida, &id);
 		} else {
-			assert((i % IDA_BITMAP_BITS) != (BITS_PER_LONG - 2));
+			assert((i % IDA_BITMAP_BITS) != BITS_PER_XA_VALUE);
 		}
 		assert(!err);
 		assert(id == i);
diff --git a/tools/testing/radix-tree/linux/radix-tree.h b/tools/testing/radix-tree/linux/radix-tree.h
index 24f13d27a8da..d1635a5bef02 100644
--- a/tools/testing/radix-tree/linux/radix-tree.h
+++ b/tools/testing/radix-tree/linux/radix-tree.h
@@ -2,7 +2,6 @@
 #ifndef _TEST_RADIX_TREE_H
 #define _TEST_RADIX_TREE_H
 
-#include "generated/map-shift.h"
 #include "../../../../include/linux/radix-tree.h"
 
 extern int kmalloc_verbose;
diff --git a/tools/testing/radix-tree/linux/xarray.h b/tools/testing/radix-tree/linux/xarray.h
new file mode 100644
index 000000000000..df3812cda376
--- /dev/null
+++ b/tools/testing/radix-tree/linux/xarray.h
@@ -0,0 +1,2 @@
+#include "generated/map-shift.h"
+#include "../../../../include/linux/xarray.h"
diff --git a/tools/testing/radix-tree/multiorder.c b/tools/testing/radix-tree/multiorder.c
index 7bf405638b0b..b8f7f53e368f 100644
--- a/tools/testing/radix-tree/multiorder.c
+++ b/tools/testing/radix-tree/multiorder.c
@@ -39,12 +39,11 @@ static void __multiorder_tag_test(int index, int order)
 
 	/*
 	 * Verify we get collisions for covered indices.  We try and fail to
-	 * insert an exceptional entry so we don't leak memory via
+	 * insert a data entry so we don't leak memory via
 	 * item_insert_order().
 	 */
 	for_each_index(i, base, order) {
-		err = __radix_tree_insert(&tree, i, order,
-				(void *)(0xA0 | RADIX_TREE_EXCEPTIONAL_ENTRY));
+		err = __radix_tree_insert(&tree, i, order, xa_mk_value(0xA0));
 		assert(err == -EEXIST);
 	}
 
@@ -380,8 +379,8 @@ static void multiorder_join1(unsigned long index,
 }
 
 /*
- * Check that the accounting of exceptional entries is handled correctly
- * by joining an exceptional entry to a normal pointer.
+ * Check that the accounting of inline data entries is handled correctly
+ * by joining a data entry to a normal pointer.
  */
 static void multiorder_join2(unsigned order1, unsigned order2)
 {
@@ -391,9 +390,9 @@ static void multiorder_join2(unsigned order1, unsigned order2)
 	void *item2;
 
 	item_insert_order(&tree, 0, order2);
-	radix_tree_insert(&tree, 1 << order2, (void *)0x12UL);
+	radix_tree_insert(&tree, 1 << order2, xa_mk_value(5));
 	item2 = __radix_tree_lookup(&tree, 1 << order2, &node, NULL);
-	assert(item2 == (void *)0x12UL);
+	assert(item2 == xa_mk_value(5));
 	assert(node->exceptional == 1);
 
 	item2 = radix_tree_lookup(&tree, 0);
@@ -407,7 +406,7 @@ static void multiorder_join2(unsigned order1, unsigned order2)
 }
 
 /*
- * This test revealed an accounting bug for exceptional entries at one point.
+ * This test revealed an accounting bug for inline data entries at one point.
  * Nodes were being freed back into the pool with an elevated exception count
  * by radix_tree_join() and then radix_tree_split() was failing to zero the
  * count of exceptional entries.
@@ -421,16 +420,16 @@ static void multiorder_join3(unsigned int order)
 	unsigned long i;
 
 	for (i = 0; i < (1 << order); i++) {
-		radix_tree_insert(&tree, i, (void *)0x12UL);
+		radix_tree_insert(&tree, i, xa_mk_value(5));
 	}
 
-	radix_tree_join(&tree, 0, order, (void *)0x16UL);
+	radix_tree_join(&tree, 0, order, xa_mk_value(7));
 	rcu_barrier();
 
 	radix_tree_split(&tree, 0, 0);
 
 	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
-		radix_tree_iter_replace(&tree, &iter, slot, (void *)0x12UL);
+		radix_tree_iter_replace(&tree, &iter, slot, xa_mk_value(5));
 	}
 
 	__radix_tree_lookup(&tree, 0, &node, NULL);
@@ -517,10 +516,10 @@ static void __multiorder_split2(int old_order, int new_order)
 	struct radix_tree_node *node;
 	void *item;
 
-	__radix_tree_insert(&tree, 0, old_order, (void *)0x12);
+	__radix_tree_insert(&tree, 0, old_order, xa_mk_value(5));
 
 	item = __radix_tree_lookup(&tree, 0, &node, NULL);
-	assert(item == (void *)0x12);
+	assert(item == xa_mk_value(5));
 	assert(node->exceptional > 0);
 
 	radix_tree_split(&tree, 0, new_order);
@@ -530,7 +529,7 @@ static void __multiorder_split2(int old_order, int new_order)
 	}
 
 	item = __radix_tree_lookup(&tree, 0, &node, NULL);
-	assert(item != (void *)0x12);
+	assert(item != xa_mk_value(5));
 	assert(node->exceptional == 0);
 
 	item_kill_tree(&tree);
@@ -544,40 +543,40 @@ static void __multiorder_split3(int old_order, int new_order)
 	struct radix_tree_node *node;
 	void *item;
 
-	__radix_tree_insert(&tree, 0, old_order, (void *)0x12);
+	__radix_tree_insert(&tree, 0, old_order, xa_mk_value(5));
 
 	item = __radix_tree_lookup(&tree, 0, &node, NULL);
-	assert(item == (void *)0x12);
+	assert(item == xa_mk_value(5));
 	assert(node->exceptional > 0);
 
 	radix_tree_split(&tree, 0, new_order);
 	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
-		radix_tree_iter_replace(&tree, &iter, slot, (void *)0x16);
+		radix_tree_iter_replace(&tree, &iter, slot, xa_mk_value(7));
 	}
 
 	item = __radix_tree_lookup(&tree, 0, &node, NULL);
-	assert(item == (void *)0x16);
+	assert(item == xa_mk_value(7));
 	assert(node->exceptional > 0);
 
 	item_kill_tree(&tree);
 
-	__radix_tree_insert(&tree, 0, old_order, (void *)0x12);
+	__radix_tree_insert(&tree, 0, old_order, xa_mk_value(5));
 
 	item = __radix_tree_lookup(&tree, 0, &node, NULL);
-	assert(item == (void *)0x12);
+	assert(item == xa_mk_value(5));
 	assert(node->exceptional > 0);
 
 	radix_tree_split(&tree, 0, new_order);
 	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
 		if (iter.index == (1 << new_order))
 			radix_tree_iter_replace(&tree, &iter, slot,
-						(void *)0x16);
+						xa_mk_value(7));
 		else
 			radix_tree_iter_replace(&tree, &iter, slot, NULL);
 	}
 
 	item = __radix_tree_lookup(&tree, 1 << new_order, &node, NULL);
-	assert(item == (void *)0x16);
+	assert(item == xa_mk_value(7));
 	assert(node->count == node->exceptional);
 	do {
 		node = node->parent;
@@ -610,13 +609,13 @@ static void multiorder_account(void)
 
 	item_insert_order(&tree, 0, 5);
 
-	__radix_tree_insert(&tree, 1 << 5, 5, (void *)0x12);
+	__radix_tree_insert(&tree, 1 << 5, 5, xa_mk_value(5));
 	__radix_tree_lookup(&tree, 0, &node, NULL);
 	assert(node->count == node->exceptional * 2);
 	radix_tree_delete(&tree, 1 << 5);
 	assert(node->exceptional == 0);
 
-	__radix_tree_insert(&tree, 1 << 5, 5, (void *)0x12);
+	__radix_tree_insert(&tree, 1 << 5, 5, xa_mk_value(5));
 	__radix_tree_lookup(&tree, 1 << 5, &node, &slot);
 	assert(node->count == node->exceptional * 2);
 	__radix_tree_replace(&tree, node, slot, NULL, NULL);
diff --git a/tools/testing/radix-tree/test.c b/tools/testing/radix-tree/test.c
index def6015570b2..62de66c314b7 100644
--- a/tools/testing/radix-tree/test.c
+++ b/tools/testing/radix-tree/test.c
@@ -295,7 +295,7 @@ void item_kill_tree(struct radix_tree_root *root)
 	int nfound;
 
 	radix_tree_for_each_slot(slot, root, &iter, 0) {
-		if (radix_tree_exceptional_entry(*slot))
+		if (xa_is_value(*slot))
 			radix_tree_delete(root, iter.index);
 	}
 
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 05/74] xarray: Change definition of sibling entries
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (3 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 04/74] xarray: Replace exceptional entries Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 06/74] xarray: Add definition of struct xarray Matthew Wilcox
                   ` (69 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Instead of storing a pointer to the slot containing the canonical entry,
store the offset of the slot.  Produces slightly more efficient code
(~300 bytes) and simplifies the implementation.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
---
 include/linux/xarray.h | 93 ++++++++++++++++++++++++++++++++++++++++++
 lib/radix-tree.c       | 64 +++++++++--------------------
 2 files changed, 112 insertions(+), 45 deletions(-)

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index e6ead6c81458..1ac55c05de14 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -22,6 +22,12 @@
  * x1: Value entry
  *
  * Attempting to store internal entries in the XArray is a bug.
+ *
+ * Most internal entries are pointers to the next node in the tree.
+ * The following internal entries have a special meaning:
+ *
+ * 0-62: Sibling entries
+ * 256: Retry entry
  */
 
 #define BITS_PER_XA_VALUE	(BITS_PER_LONG - 1)
@@ -63,6 +69,42 @@ static inline bool xa_is_value(const void *entry)
 	return (unsigned long)entry & 1;
 }
 
+/*
+ * xa_mk_internal() - Create an internal entry.
+ * @v: Value to turn into an internal entry.
+ *
+ * Context: Any context.
+ * Return: An XArray internal entry corresponding to this value.
+ */
+static inline void *xa_mk_internal(unsigned long v)
+{
+	return (void *)((v << 2) | 2);
+}
+
+/*
+ * xa_to_internal() - Extract the value from an internal entry.
+ * @entry: XArray entry.
+ *
+ * Context: Any context.
+ * Return: The value which was stored in the internal entry.
+ */
+static inline unsigned long xa_to_internal(const void *entry)
+{
+	return (unsigned long)entry >> 2;
+}
+
+/*
+ * xa_is_internal() - Is the entry an internal entry?
+ * @entry: XArray entry.
+ *
+ * Context: Any context.
+ * Return: %true if the entry is an internal entry.
+ */
+static inline bool xa_is_internal(const void *entry)
+{
+	return ((unsigned long)entry & 3) == 2;
+}
+
 #define xa_trylock(xa)		spin_trylock(&(xa)->xa_lock)
 #define xa_lock(xa)		spin_lock(&(xa)->xa_lock)
 #define xa_unlock(xa)		spin_unlock(&(xa)->xa_lock)
@@ -75,4 +117,55 @@ static inline bool xa_is_value(const void *entry)
 #define xa_unlock_irqrestore(xa, flags) \
 				spin_unlock_irqrestore(&(xa)->xa_lock, flags)
 
+/* Everything below here is the Advanced API.  Proceed with caution. */
+
+/*
+ * The xarray is constructed out of a set of 'chunks' of pointers.  Choosing
+ * the best chunk size requires some tradeoffs.  A power of two recommends
+ * itself so that we can walk the tree based purely on shifts and masks.
+ * Generally, the larger the better; as the number of slots per level of the
+ * tree increases, the less tall the tree needs to be.  But that needs to be
+ * balanced against the memory consumption of each node.  On a 64-bit system,
+ * xa_node is currently 576 bytes, and we get 7 of them per 4kB page.  If we
+ * doubled the number of slots per node, we'd get only 3 nodes per 4kB page.
+ */
+#ifndef XA_CHUNK_SHIFT
+#define XA_CHUNK_SHIFT		(CONFIG_BASE_SMALL ? 4 : 6)
+#endif
+#define XA_CHUNK_SIZE		(1UL << XA_CHUNK_SHIFT)
+#define XA_CHUNK_MASK		(XA_CHUNK_SIZE - 1)
+
+/* Private */
+static inline bool xa_is_node(const void *entry)
+{
+	return xa_is_internal(entry) && (unsigned long)entry > 4096;
+}
+
+/* Private */
+static inline void *xa_mk_sibling(unsigned int offset)
+{
+	return xa_mk_internal(offset);
+}
+
+/* Private */
+static inline unsigned long xa_to_sibling(const void *entry)
+{
+	return xa_to_internal(entry);
+}
+
+/**
+ * xa_is_sibling() - Is the entry a sibling entry?
+ * @entry: Entry retrieved from the XArray
+ *
+ * Return: %true if the entry is a sibling entry.
+ */
+static inline bool xa_is_sibling(const void *entry)
+{
+	return IS_ENABLED(CONFIG_RADIX_TREE_MULTIORDER) &&
+		xa_is_internal(entry) &&
+		(entry < xa_mk_sibling(XA_CHUNK_SIZE - 1));
+}
+
+#define XA_RETRY_ENTRY		xa_mk_internal(256)
+
 #endif /* _LINUX_XARRAY_H */
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index fa43dcdc1f6a..22ca63cb3204 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -38,6 +38,7 @@
 #include <linux/rcupdate.h>
 #include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/xarray.h>
 
 
 /* Number of nodes in fully populated tree of given height */
@@ -98,24 +99,7 @@ static inline void *node_to_entry(void *ptr)
 	return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE);
 }
 
-#define RADIX_TREE_RETRY	node_to_entry(NULL)
-
-#ifdef CONFIG_RADIX_TREE_MULTIORDER
-/* Sibling slots point directly to another slot in the same node */
-static inline
-bool is_sibling_entry(const struct radix_tree_node *parent, void *node)
-{
-	void __rcu **ptr = node;
-	return (parent->slots <= ptr) &&
-			(ptr < parent->slots + RADIX_TREE_MAP_SIZE);
-}
-#else
-static inline
-bool is_sibling_entry(const struct radix_tree_node *parent, void *node)
-{
-	return false;
-}
-#endif
+#define RADIX_TREE_RETRY	XA_RETRY_ENTRY
 
 static inline unsigned long
 get_slot_offset(const struct radix_tree_node *parent, void __rcu **slot)
@@ -129,16 +113,10 @@ static unsigned int radix_tree_descend(const struct radix_tree_node *parent,
 	unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK;
 	void __rcu **entry = rcu_dereference_raw(parent->slots[offset]);
 
-#ifdef CONFIG_RADIX_TREE_MULTIORDER
-	if (radix_tree_is_internal_node(entry)) {
-		if (is_sibling_entry(parent, entry)) {
-			void __rcu **sibentry;
-			sibentry = (void __rcu **) entry_to_node(entry);
-			offset = get_slot_offset(parent, sibentry);
-			entry = rcu_dereference_raw(*sibentry);
-		}
+	if (xa_is_sibling(entry)) {
+		offset = xa_to_sibling(entry);
+		entry = rcu_dereference_raw(parent->slots[offset]);
 	}
-#endif
 
 	*nodep = (void *)entry;
 	return offset;
@@ -300,10 +278,10 @@ static void dump_node(struct radix_tree_node *node, unsigned long index)
 		} else if (!radix_tree_is_internal_node(entry)) {
 			pr_debug("radix entry %p offset %ld indices %lu-%lu parent %p\n",
 					entry, i, first, last, node);
-		} else if (is_sibling_entry(node, entry)) {
+		} else if (xa_is_sibling(entry)) {
 			pr_debug("radix sblng %p offset %ld indices %lu-%lu parent %p val %p\n",
 					entry, i, first, last, node,
-					*(void **)entry_to_node(entry));
+					node->slots[xa_to_sibling(entry)]);
 		} else {
 			dump_node(entry_to_node(entry), first);
 		}
@@ -873,8 +851,7 @@ static void radix_tree_free_nodes(struct radix_tree_node *node)
 
 	for (;;) {
 		void *entry = rcu_dereference_raw(child->slots[offset]);
-		if (radix_tree_is_internal_node(entry) &&
-					!is_sibling_entry(child, entry)) {
+		if (xa_is_node(entry)) {
 			child = entry_to_node(entry);
 			offset = 0;
 			continue;
@@ -896,7 +873,7 @@ static void radix_tree_free_nodes(struct radix_tree_node *node)
 static inline int insert_entries(struct radix_tree_node *node,
 		void __rcu **slot, void *item, unsigned order, bool replace)
 {
-	struct radix_tree_node *child;
+	void *sibling;
 	unsigned i, n, tag, offset, tags = 0;
 
 	if (node) {
@@ -914,7 +891,7 @@ static inline int insert_entries(struct radix_tree_node *node,
 		offset = offset & ~(n - 1);
 		slot = &node->slots[offset];
 	}
-	child = node_to_entry(slot);
+	sibling = xa_mk_sibling(offset);
 
 	for (i = 0; i < n; i++) {
 		if (slot[i]) {
@@ -931,7 +908,7 @@ static inline int insert_entries(struct radix_tree_node *node,
 	for (i = 0; i < n; i++) {
 		struct radix_tree_node *old = rcu_dereference_raw(slot[i]);
 		if (i) {
-			rcu_assign_pointer(slot[i], child);
+			rcu_assign_pointer(slot[i], sibling);
 			for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
 				if (tags & (1 << tag))
 					tag_clear(node, tag, offset + i);
@@ -941,9 +918,7 @@ static inline int insert_entries(struct radix_tree_node *node,
 				if (tags & (1 << tag))
 					tag_set(node, tag, offset);
 		}
-		if (radix_tree_is_internal_node(old) &&
-					!is_sibling_entry(node, old) &&
-					(old != RADIX_TREE_RETRY))
+		if (xa_is_node(old))
 			radix_tree_free_nodes(old);
 		if (xa_is_value(old))
 			node->exceptional--;
@@ -1102,10 +1077,10 @@ static inline void replace_sibling_entries(struct radix_tree_node *node,
 				void __rcu **slot, int count, int exceptional)
 {
 #ifdef CONFIG_RADIX_TREE_MULTIORDER
-	void *ptr = node_to_entry(slot);
-	unsigned offset = get_slot_offset(node, slot) + 1;
+	unsigned offset = get_slot_offset(node, slot);
+	void *ptr = xa_mk_sibling(offset);
 
-	while (offset < RADIX_TREE_MAP_SIZE) {
+	while (++offset < RADIX_TREE_MAP_SIZE) {
 		if (rcu_dereference_raw(node->slots[offset]) != ptr)
 			break;
 		if (count < 0) {
@@ -1113,7 +1088,6 @@ static inline void replace_sibling_entries(struct radix_tree_node *node,
 			node->count--;
 		}
 		node->exceptional += exceptional;
-		offset++;
 	}
 #endif
 }
@@ -1312,8 +1286,7 @@ int radix_tree_split(struct radix_tree_root *root, unsigned long index,
 			tags |= 1 << tag;
 
 	for (end = offset + 1; end < RADIX_TREE_MAP_SIZE; end++) {
-		if (!is_sibling_entry(parent,
-				rcu_dereference_raw(parent->slots[end])))
+		if (!xa_is_sibling(rcu_dereference_raw(parent->slots[end])))
 			break;
 		for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
 			if (tags & (1 << tag))
@@ -1611,7 +1584,7 @@ static void __rcu **skip_siblings(struct radix_tree_node **nodep,
 {
 	while (iter->index < iter->next_index) {
 		*nodep = rcu_dereference_raw(*slot);
-		if (*nodep && !is_sibling_entry(iter->node, *nodep))
+		if (*nodep && !xa_is_sibling(*nodep))
 			return slot;
 		slot++;
 		iter->index = __radix_tree_iter_add(iter, 1);
@@ -1762,7 +1735,7 @@ void __rcu **radix_tree_next_chunk(const struct radix_tree_root *root,
 				while (++offset	< RADIX_TREE_MAP_SIZE) {
 					void *slot = rcu_dereference_raw(
 							node->slots[offset]);
-					if (is_sibling_entry(node, slot))
+					if (xa_is_sibling(slot))
 						continue;
 					if (slot)
 						break;
@@ -2283,6 +2256,7 @@ void __init radix_tree_init(void)
 
 	BUILD_BUG_ON(RADIX_TREE_MAX_TAGS + __GFP_BITS_SHIFT > 32);
 	BUILD_BUG_ON(ROOT_IS_IDR & ~GFP_ZONEMASK);
+	BUILD_BUG_ON(XA_CHUNK_SIZE > 255);
 	radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
 			sizeof(struct radix_tree_node), 0,
 			SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 06/74] xarray: Add definition of struct xarray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (4 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 05/74] xarray: Change definition of sibling entries Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 07/74] xarray: Define struct xa_node Matthew Wilcox
                   ` (68 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

This is a direct replacement for struct radix_tree_root.  Some of the
struct members have changed name; convert those, and use a #define so
that radix_tree users continue to work without change.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
---
 include/linux/radix-tree.h               | 33 +++--------
 include/linux/xarray.h                   | 61 +++++++++++++++++++
 lib/Makefile                             |  2 +-
 lib/idr.c                                |  4 +-
 lib/radix-tree.c                         | 75 ++++++++++++------------
 lib/xarray.c                             | 44 ++++++++++++++
 tools/testing/radix-tree/Makefile        |  7 ++-
 tools/testing/radix-tree/linux/bug.h     |  1 +
 tools/testing/radix-tree/linux/kconfig.h |  1 +
 tools/testing/radix-tree/multiorder.c    |  6 +-
 tools/testing/radix-tree/test.c          |  6 +-
 tools/testing/radix-tree/xarray.c        |  7 +++
 12 files changed, 174 insertions(+), 73 deletions(-)
 create mode 100644 lib/xarray.c
 create mode 100644 tools/testing/radix-tree/linux/kconfig.h
 create mode 100644 tools/testing/radix-tree/xarray.c

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 87f35fe00e55..c8a33e9e9a3c 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -30,6 +30,9 @@
 #include <linux/types.h>
 #include <linux/xarray.h>
 
+/* Keep unconverted code working */
+#define radix_tree_root		xarray
+
 /*
  * The bottom two bits of the slot determine how the remaining bits in the
  * slot are interpreted:
@@ -59,10 +62,7 @@ static inline bool radix_tree_is_internal_node(void *ptr)
 
 #define RADIX_TREE_MAX_TAGS 3
 
-#ifndef RADIX_TREE_MAP_SHIFT
-#define RADIX_TREE_MAP_SHIFT	(CONFIG_BASE_SMALL ? 4 : 6)
-#endif
-
+#define RADIX_TREE_MAP_SHIFT	XA_CHUNK_SHIFT
 #define RADIX_TREE_MAP_SIZE	(1UL << RADIX_TREE_MAP_SHIFT)
 #define RADIX_TREE_MAP_MASK	(RADIX_TREE_MAP_SIZE-1)
 
@@ -95,36 +95,21 @@ struct radix_tree_node {
 	unsigned long	tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS];
 };
 
-/* The IDR tag is stored in the low bits of the GFP flags */
+/* The IDR tag is stored in the low bits of xa_flags */
 #define ROOT_IS_IDR	((__force gfp_t)4)
-/* The top bits of gfp_mask are used to store the root tags */
+/* The top bits of xa_flags are used to store the root tags */
 #define ROOT_TAG_SHIFT	(__GFP_BITS_SHIFT)
 
-struct radix_tree_root {
-	spinlock_t		xa_lock;
-	gfp_t			gfp_mask;
-	struct radix_tree_node	__rcu *rnode;
-};
-
-#define RADIX_TREE_INIT(name, mask)	{				\
-	.xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock),			\
-	.gfp_mask = (mask),						\
-	.rnode = NULL,							\
-}
+#define RADIX_TREE_INIT(name, mask)	XARRAY_INIT_FLAGS(name, mask)
 
 #define RADIX_TREE(name, mask) \
 	struct radix_tree_root name = RADIX_TREE_INIT(name, mask)
 
-#define INIT_RADIX_TREE(root, mask)					\
-do {									\
-	spin_lock_init(&(root)->xa_lock);				\
-	(root)->gfp_mask = (mask);					\
-	(root)->rnode = NULL;						\
-} while (0)
+#define INIT_RADIX_TREE(root, mask) xa_init_flags(root, mask)
 
 static inline bool radix_tree_empty(const struct radix_tree_root *root)
 {
-	return root->rnode == NULL;
+	return root->xa_head == NULL;
 }
 
 /**
diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 1ac55c05de14..43e102616a70 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -10,6 +10,8 @@
  */
 
 #include <linux/bug.h>
+#include <linux/compiler.h>
+#include <linux/kconfig.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
 
@@ -105,6 +107,65 @@ static inline bool xa_is_internal(const void *entry)
 	return ((unsigned long)entry & 3) == 2;
 }
 
+/**
+ * struct xarray - The anchor of the XArray.
+ * @xa_lock: Lock that protects the contents of the XArray.
+ *
+ * To use the xarray, define it statically or embed it in your data structure.
+ * It is a very small data structure, so it does not usually make sense to
+ * allocate it separately and keep a pointer to it in your data structure.
+ *
+ * You may use the xa_lock to protect your own data structures as well.
+ */
+/*
+ * If all of the entries in the array are NULL, @xa_head is a NULL pointer.
+ * If the only non-NULL entry in the array is at index 0, @xa_head is that
+ * entry.  If any other entry in the array is non-NULL, @xa_head points
+ * to an @xa_node.
+ */
+struct xarray {
+	spinlock_t	xa_lock;
+/* private: The rest of the data structure is not to be used directly. */
+	gfp_t		xa_flags;
+	void __rcu *	xa_head;
+};
+
+#define XARRAY_INIT_FLAGS(name, flags) {			\
+	.xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock),		\
+	.xa_flags = flags,					\
+	.xa_head = NULL,					\
+}
+
+#define XARRAY_INIT(name) XARRAY_INIT_FLAGS(name, 0)
+
+/**
+ * DEFINE_XARRAY() - Define an XArray
+ * @name: A string that names your XArray
+ *
+ * This is intended for file scope definitions of XArrays.  It declares
+ * and initialises an empty XArray with the chosen name.  It is equivalent
+ * to calling xa_init() on the array, but it does the initialisation at
+ * compiletime instead of runtime.
+ */
+#define DEFINE_XARRAY(name) struct xarray name = XARRAY_INIT(name)
+#define DEFINE_XARRAY_FLAGS(name, flags) \
+			struct xarray name = XARRAY_INIT_FLAGS(name, flags)
+
+void xa_init_flags(struct xarray *, gfp_t flags);
+
+/**
+ * xa_init() - Initialise an empty XArray.
+ * @xa: XArray.
+ *
+ * An empty XArray is full of NULL entries.
+ *
+ * Context: Any context.
+ */
+static inline void xa_init(struct xarray *xa)
+{
+	xa_init_flags(xa, 0);
+}
+
 #define xa_trylock(xa)		spin_trylock(&(xa)->xa_lock)
 #define xa_lock(xa)		spin_lock(&(xa)->xa_lock)
 #define xa_unlock(xa)		spin_unlock(&(xa)->xa_lock)
diff --git a/lib/Makefile b/lib/Makefile
index 956b320292fe..507e5df0512d 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -18,7 +18,7 @@ KCOV_INSTRUMENT_debugobjects.o := n
 KCOV_INSTRUMENT_dynamic_debug.o := n
 
 lib-y := ctype.o string.o vsprintf.o cmdline.o \
-	 rbtree.o radix-tree.o timerqueue.o\
+	 rbtree.o radix-tree.o timerqueue.o xarray.o \
 	 idr.o int_sqrt.o extable.o \
 	 sha1.o chacha20.o irq_regs.o argv_split.o \
 	 flex_proportions.o ratelimit.o show_mem.o \
diff --git a/lib/idr.c b/lib/idr.c
index 3bdcb32760e3..0d7410d1fb7c 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -41,8 +41,8 @@ int idr_alloc_u32(struct idr *idr, void *ptr, u32 *nextid,
 
 	if (WARN_ON_ONCE(radix_tree_is_internal_node(ptr)))
 		return -EINVAL;
-	if (WARN_ON_ONCE(!(idr->idr_rt.gfp_mask & ROOT_IS_IDR)))
-		idr->idr_rt.gfp_mask |= IDR_RT_MARKER;
+	if (WARN_ON_ONCE(!(idr->idr_rt.xa_flags & ROOT_IS_IDR)))
+		idr->idr_rt.xa_flags |= IDR_RT_MARKER;
 
 	id = (id < base) ? 0 : id - base;
 	radix_tree_iter_init(&iter, id);
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 22ca63cb3204..2f57c98c4da6 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -124,7 +124,7 @@ static unsigned int radix_tree_descend(const struct radix_tree_node *parent,
 
 static inline gfp_t root_gfp_mask(const struct radix_tree_root *root)
 {
-	return root->gfp_mask & (__GFP_BITS_MASK & ~GFP_ZONEMASK);
+	return root->xa_flags & (__GFP_BITS_MASK & ~GFP_ZONEMASK);
 }
 
 static inline void tag_set(struct radix_tree_node *node, unsigned int tag,
@@ -147,32 +147,32 @@ static inline int tag_get(const struct radix_tree_node *node, unsigned int tag,
 
 static inline void root_tag_set(struct radix_tree_root *root, unsigned tag)
 {
-	root->gfp_mask |= (__force gfp_t)(1 << (tag + ROOT_TAG_SHIFT));
+	root->xa_flags |= (__force gfp_t)(1 << (tag + ROOT_TAG_SHIFT));
 }
 
 static inline void root_tag_clear(struct radix_tree_root *root, unsigned tag)
 {
-	root->gfp_mask &= (__force gfp_t)~(1 << (tag + ROOT_TAG_SHIFT));
+	root->xa_flags &= (__force gfp_t)~(1 << (tag + ROOT_TAG_SHIFT));
 }
 
 static inline void root_tag_clear_all(struct radix_tree_root *root)
 {
-	root->gfp_mask &= (1 << ROOT_TAG_SHIFT) - 1;
+	root->xa_flags &= (__force gfp_t)((1 << ROOT_TAG_SHIFT) - 1);
 }
 
 static inline int root_tag_get(const struct radix_tree_root *root, unsigned tag)
 {
-	return (__force int)root->gfp_mask & (1 << (tag + ROOT_TAG_SHIFT));
+	return (__force int)root->xa_flags & (1 << (tag + ROOT_TAG_SHIFT));
 }
 
 static inline unsigned root_tags_get(const struct radix_tree_root *root)
 {
-	return (__force unsigned)root->gfp_mask >> ROOT_TAG_SHIFT;
+	return (__force unsigned)root->xa_flags >> ROOT_TAG_SHIFT;
 }
 
 static inline bool is_idr(const struct radix_tree_root *root)
 {
-	return !!(root->gfp_mask & ROOT_IS_IDR);
+	return !!(root->xa_flags & ROOT_IS_IDR);
 }
 
 /*
@@ -291,12 +291,12 @@ static void dump_node(struct radix_tree_node *node, unsigned long index)
 /* For debug */
 static void radix_tree_dump(struct radix_tree_root *root)
 {
-	pr_debug("radix root: %p rnode %p tags %x\n",
-			root, root->rnode,
-			root->gfp_mask >> ROOT_TAG_SHIFT);
-	if (!radix_tree_is_internal_node(root->rnode))
+	pr_debug("radix root: %p xa_head %p tags %x\n",
+			root, root->xa_head,
+			root->xa_flags >> ROOT_TAG_SHIFT);
+	if (!radix_tree_is_internal_node(root->xa_head))
 		return;
-	dump_node(entry_to_node(root->rnode), 0);
+	dump_node(entry_to_node(root->xa_head), 0);
 }
 
 static void dump_ida_node(void *entry, unsigned long index)
@@ -340,9 +340,9 @@ static void dump_ida_node(void *entry, unsigned long index)
 static void ida_dump(struct ida *ida)
 {
 	struct radix_tree_root *root = &ida->ida_rt;
-	pr_debug("ida: %p node %p free %d\n", ida, root->rnode,
-				root->gfp_mask >> ROOT_TAG_SHIFT);
-	dump_ida_node(root->rnode, 0);
+	pr_debug("ida: %p node %p free %d\n", ida, root->xa_head,
+				root->xa_flags >> ROOT_TAG_SHIFT);
+	dump_ida_node(root->xa_head, 0);
 }
 #endif
 
@@ -576,7 +576,7 @@ int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order)
 static unsigned radix_tree_load_root(const struct radix_tree_root *root,
 		struct radix_tree_node **nodep, unsigned long *maxindex)
 {
-	struct radix_tree_node *node = rcu_dereference_raw(root->rnode);
+	struct radix_tree_node *node = rcu_dereference_raw(root->xa_head);
 
 	*nodep = node;
 
@@ -605,7 +605,7 @@ static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp,
 	while (index > shift_maxindex(maxshift))
 		maxshift += RADIX_TREE_MAP_SHIFT;
 
-	entry = rcu_dereference_raw(root->rnode);
+	entry = rcu_dereference_raw(root->xa_head);
 	if (!entry && (!is_idr(root) || root_tag_get(root, IDR_FREE)))
 		goto out;
 
@@ -633,7 +633,7 @@ static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp,
 		if (radix_tree_is_internal_node(entry)) {
 			entry_to_node(entry)->parent = node;
 		} else if (xa_is_value(entry)) {
-			/* Moving an exceptional root->rnode to a node */
+			/* Moving an exceptional root->xa_head to a node */
 			node->exceptional = 1;
 		}
 		/*
@@ -642,7 +642,7 @@ static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp,
 		 */
 		node->slots[0] = (void __rcu *)entry;
 		entry = node_to_entry(node);
-		rcu_assign_pointer(root->rnode, entry);
+		rcu_assign_pointer(root->xa_head, entry);
 		shift += RADIX_TREE_MAP_SHIFT;
 	} while (shift <= maxshift);
 out:
@@ -659,7 +659,7 @@ static inline bool radix_tree_shrink(struct radix_tree_root *root,
 	bool shrunk = false;
 
 	for (;;) {
-		struct radix_tree_node *node = rcu_dereference_raw(root->rnode);
+		struct radix_tree_node *node = rcu_dereference_raw(root->xa_head);
 		struct radix_tree_node *child;
 
 		if (!radix_tree_is_internal_node(node))
@@ -687,9 +687,9 @@ static inline bool radix_tree_shrink(struct radix_tree_root *root,
 		 * moving the node from one part of the tree to another: if it
 		 * was safe to dereference the old pointer to it
 		 * (node->slots[0]), it will be safe to dereference the new
-		 * one (root->rnode) as far as dependent read barriers go.
+		 * one (root->xa_head) as far as dependent read barriers go.
 		 */
-		root->rnode = (void __rcu *)child;
+		root->xa_head = (void __rcu *)child;
 		if (is_idr(root) && !tag_get(node, IDR_FREE, 0))
 			root_tag_clear(root, IDR_FREE);
 
@@ -737,9 +737,8 @@ static bool delete_node(struct radix_tree_root *root,
 
 		if (node->count) {
 			if (node_to_entry(node) ==
-					rcu_dereference_raw(root->rnode))
-				deleted |= radix_tree_shrink(root,
-								update_node);
+					rcu_dereference_raw(root->xa_head))
+				deleted |= radix_tree_shrink(root, update_node);
 			return deleted;
 		}
 
@@ -754,7 +753,7 @@ static bool delete_node(struct radix_tree_root *root,
 			 */
 			if (!is_idr(root))
 				root_tag_clear_all(root);
-			root->rnode = NULL;
+			root->xa_head = NULL;
 		}
 
 		WARN_ON_ONCE(!list_empty(&node->private_list));
@@ -779,7 +778,7 @@ static bool delete_node(struct radix_tree_root *root,
  *	at position @index in the radix tree @root.
  *
  *	Until there is more than one item in the tree, no nodes are
- *	allocated and @root->rnode is used as a direct slot instead of
+ *	allocated and @root->xa_head is used as a direct slot instead of
  *	pointing to a node, in which case *@nodep will be NULL.
  *
  *	Returns -ENOMEM, or 0 for success.
@@ -789,7 +788,7 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
 			void __rcu ***slotp)
 {
 	struct radix_tree_node *node = NULL, *child;
-	void __rcu **slot = (void __rcu **)&root->rnode;
+	void __rcu **slot = (void __rcu **)&root->xa_head;
 	unsigned long maxindex;
 	unsigned int shift, offset = 0;
 	unsigned long max = index | ((1UL << order) - 1);
@@ -805,7 +804,7 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
 		if (error < 0)
 			return error;
 		shift = error;
-		child = rcu_dereference_raw(root->rnode);
+		child = rcu_dereference_raw(root->xa_head);
 	}
 
 	while (shift > order) {
@@ -996,7 +995,7 @@ EXPORT_SYMBOL(__radix_tree_insert);
  *	tree @root.
  *
  *	Until there is more than one item in the tree, no nodes are
- *	allocated and @root->rnode is used as a direct slot instead of
+ *	allocated and @root->xa_head is used as a direct slot instead of
  *	pointing to a node, in which case *@nodep will be NULL.
  */
 void *__radix_tree_lookup(const struct radix_tree_root *root,
@@ -1009,7 +1008,7 @@ void *__radix_tree_lookup(const struct radix_tree_root *root,
 
  restart:
 	parent = NULL;
-	slot = (void __rcu **)&root->rnode;
+	slot = (void __rcu **)&root->xa_head;
 	radix_tree_load_root(root, &node, &maxindex);
 	if (index > maxindex)
 		return NULL;
@@ -1161,9 +1160,9 @@ void __radix_tree_replace(struct radix_tree_root *root,
 	/*
 	 * This function supports replacing exceptional entries and
 	 * deleting entries, but that needs accounting against the
-	 * node unless the slot is root->rnode.
+	 * node unless the slot is root->xa_head.
 	 */
-	WARN_ON_ONCE(!node && (slot != (void __rcu **)&root->rnode) &&
+	WARN_ON_ONCE(!node && (slot != (void __rcu **)&root->xa_head) &&
 			(count || exceptional));
 	replace_slot(slot, item, node, count, exceptional);
 
@@ -1715,7 +1714,7 @@ void __rcu **radix_tree_next_chunk(const struct radix_tree_root *root,
 		iter->tags = 1;
 		iter->node = NULL;
 		__set_iter_shift(iter, 0);
-		return (void __rcu **)&root->rnode;
+		return (void __rcu **)&root->xa_head;
 	}
 
 	do {
@@ -2111,7 +2110,7 @@ void __rcu **idr_get_free(struct radix_tree_root *root,
 			      unsigned long max)
 {
 	struct radix_tree_node *node = NULL, *child;
-	void __rcu **slot = (void __rcu **)&root->rnode;
+	void __rcu **slot = (void __rcu **)&root->xa_head;
 	unsigned long maxindex, start = iter->next_index;
 	unsigned int shift, offset = 0;
 
@@ -2127,7 +2126,7 @@ void __rcu **idr_get_free(struct radix_tree_root *root,
 		if (error < 0)
 			return ERR_PTR(error);
 		shift = error;
-		child = rcu_dereference_raw(root->rnode);
+		child = rcu_dereference_raw(root->xa_head);
 	}
 
 	while (shift) {
@@ -2190,10 +2189,10 @@ void __rcu **idr_get_free(struct radix_tree_root *root,
  */
 void idr_destroy(struct idr *idr)
 {
-	struct radix_tree_node *node = rcu_dereference_raw(idr->idr_rt.rnode);
+	struct radix_tree_node *node = rcu_dereference_raw(idr->idr_rt.xa_head);
 	if (radix_tree_is_internal_node(node))
 		radix_tree_free_nodes(node);
-	idr->idr_rt.rnode = NULL;
+	idr->idr_rt.xa_head = NULL;
 	root_tag_set(&idr->idr_rt, IDR_FREE);
 }
 EXPORT_SYMBOL(idr_destroy);
diff --git a/lib/xarray.c b/lib/xarray.c
new file mode 100644
index 000000000000..3da0346f8f8f
--- /dev/null
+++ b/lib/xarray.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * XArray implementation
+ * Copyright (c) 2017 Microsoft Corporation
+ * Author: Matthew Wilcox <willy@infradead.org>
+ */
+
+#include <linux/export.h>
+#include <linux/xarray.h>
+
+/*
+ * Coding conventions in this file:
+ *
+ * @xa is used to refer to the entire xarray.
+ * @xas is the 'xarray operation state'.  It may be either a pointer to
+ * an xa_state, or an xa_state stored on the stack.  This is an unfortunate
+ * ambiguity.
+ * @index is the index of the entry being operated on
+ * @tag is an xa_tag_t; a small number indicating one of the tag bits.
+ * @node refers to an xa_node; usually the primary one being operated on by
+ * this function.
+ * @offset is the index into the slots array inside an xa_node.
+ * @parent refers to the @xa_node closer to the head than @node.
+ * @entry refers to something stored in a slot in the xarray
+ */
+
+/**
+ * xa_init_flags() - Initialise an empty XArray with flags.
+ * @xa: XArray.
+ * @flags: XA_FLAG values.
+ *
+ * If you need to initialise an XArray with special flags (eg you need
+ * to take the lock from interrupt context), use this function instead
+ * of xa_init().
+ *
+ * Context: Any context.
+ */
+void xa_init_flags(struct xarray *xa, gfp_t flags)
+{
+	spin_lock_init(&xa->xa_lock);
+	xa->xa_flags = flags;
+	xa->xa_head = NULL;
+}
+EXPORT_SYMBOL(xa_init_flags);
diff --git a/tools/testing/radix-tree/Makefile b/tools/testing/radix-tree/Makefile
index da030a65d6d6..0f9aa462829d 100644
--- a/tools/testing/radix-tree/Makefile
+++ b/tools/testing/radix-tree/Makefile
@@ -5,7 +5,7 @@ CFLAGS += -I. -I../../include -g -Og -Wall -D_LGPL_SOURCE -fsanitize=address \
 LDFLAGS += -fsanitize=address -fsanitize=undefined
 LDLIBS+= -lpthread -lurcu
 TARGETS = main idr-test multiorder
-CORE_OFILES := radix-tree.o idr.o linux.o test.o find_bit.o
+CORE_OFILES := xarray.o radix-tree.o idr.o linux.o test.o find_bit.o
 OFILES = main.o $(CORE_OFILES) regression1.o regression2.o regression3.o \
 	 tag_check.o multiorder.o idr-test.o iteration_check.o benchmark.o
 
@@ -34,6 +34,7 @@ vpath %.c ../../lib
 $(OFILES): Makefile *.h */*.h generated/map-shift.h \
 	../../include/linux/*.h \
 	../../include/asm/*.h \
+	../../../include/linux/xarray.h \
 	../../../include/linux/radix-tree.h \
 	../../../include/linux/idr.h
 
@@ -43,8 +44,10 @@ radix-tree.c: ../../../lib/radix-tree.c
 idr.c: ../../../lib/idr.c
 	sed -e 's/^static //' -e 's/__always_inline //' -e 's/inline //' < $< > $@
 
+xarray.o: ../../../lib/xarray.c
+
 generated/map-shift.h:
 	@if ! grep -qws $(SHIFT) generated/map-shift.h; then		\
-		echo "#define RADIX_TREE_MAP_SHIFT $(SHIFT)" >		\
+		echo "#define XA_CHUNK_SHIFT $(SHIFT)" >		\
 				generated/map-shift.h;			\
 	fi
diff --git a/tools/testing/radix-tree/linux/bug.h b/tools/testing/radix-tree/linux/bug.h
index 23b8ed52f8c8..03dc8a57eb99 100644
--- a/tools/testing/radix-tree/linux/bug.h
+++ b/tools/testing/radix-tree/linux/bug.h
@@ -1 +1,2 @@
+#include <stdio.h>
 #include "asm/bug.h"
diff --git a/tools/testing/radix-tree/linux/kconfig.h b/tools/testing/radix-tree/linux/kconfig.h
new file mode 100644
index 000000000000..6c8675859913
--- /dev/null
+++ b/tools/testing/radix-tree/linux/kconfig.h
@@ -0,0 +1 @@
+#include "../../../../include/linux/kconfig.h"
diff --git a/tools/testing/radix-tree/multiorder.c b/tools/testing/radix-tree/multiorder.c
index b8f7f53e368f..3bba18e1ba65 100644
--- a/tools/testing/radix-tree/multiorder.c
+++ b/tools/testing/radix-tree/multiorder.c
@@ -192,13 +192,13 @@ static void multiorder_shrink(unsigned long index, int order)
 
 	assert(item_insert_order(&tree, 0, order) == 0);
 
-	node = tree.rnode;
+	node = tree.xa_head;
 
 	assert(item_insert(&tree, index) == 0);
-	assert(node != tree.rnode);
+	assert(node != tree.xa_head);
 
 	assert(item_delete(&tree, index) != 0);
-	assert(node == tree.rnode);
+	assert(node == tree.xa_head);
 
 	for (i = 0; i < max; i++) {
 		struct item *item = item_lookup(&tree, i);
diff --git a/tools/testing/radix-tree/test.c b/tools/testing/radix-tree/test.c
index 62de66c314b7..70ddf964d51c 100644
--- a/tools/testing/radix-tree/test.c
+++ b/tools/testing/radix-tree/test.c
@@ -281,7 +281,7 @@ static int verify_node(struct radix_tree_node *slot, unsigned int tag,
 
 void verify_tag_consistency(struct radix_tree_root *root, unsigned int tag)
 {
-	struct radix_tree_node *node = root->rnode;
+	struct radix_tree_node *node = root->xa_head;
 	if (!radix_tree_is_internal_node(node))
 		return;
 	verify_node(node, tag, !!root_tag_get(root, tag));
@@ -311,13 +311,13 @@ void item_kill_tree(struct radix_tree_root *root)
 		}
 	}
 	assert(radix_tree_gang_lookup(root, (void **)items, 0, 32) == 0);
-	assert(root->rnode == NULL);
+	assert(root->xa_head == NULL);
 }
 
 void tree_verify_min_height(struct radix_tree_root *root, int maxindex)
 {
 	unsigned shift;
-	struct radix_tree_node *node = root->rnode;
+	struct radix_tree_node *node = root->xa_head;
 	if (!radix_tree_is_internal_node(node)) {
 		assert(maxindex == 0);
 		return;
diff --git a/tools/testing/radix-tree/xarray.c b/tools/testing/radix-tree/xarray.c
new file mode 100644
index 000000000000..9bbd667172a7
--- /dev/null
+++ b/tools/testing/radix-tree/xarray.c
@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * xarray.c: Userspace shim for XArray test-suite
+ * Copyright (c) 2018 Matthew Wilcox <willy@infradead.org>
+ */
+
+#include "../../../lib/xarray.c"
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 07/74] xarray: Define struct xa_node
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (5 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 06/74] xarray: Add definition of struct xarray Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 08/74] xarray: Add documentation Matthew Wilcox
                   ` (67 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

This is a direct replacement for struct radix_tree_node.  A couple of
struct members have changed name, so convert those.  Use a #define so
that radix tree users continue to work without change.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
---
 include/linux/radix-tree.h            | 29 ++--------------
 include/linux/xarray.h                | 24 ++++++++++++++
 lib/radix-tree.c                      | 48 +++++++++++++--------------
 mm/workingset.c                       | 16 ++++-----
 tools/testing/radix-tree/multiorder.c | 30 ++++++++---------
 5 files changed, 74 insertions(+), 73 deletions(-)

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index c8a33e9e9a3c..f64beb9ba175 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -32,6 +32,7 @@
 
 /* Keep unconverted code working */
 #define radix_tree_root		xarray
+#define radix_tree_node		xa_node
 
 /*
  * The bottom two bits of the slot determine how the remaining bits in the
@@ -60,41 +61,17 @@ static inline bool radix_tree_is_internal_node(void *ptr)
 
 /*** radix-tree API starts here ***/
 
-#define RADIX_TREE_MAX_TAGS 3
-
 #define RADIX_TREE_MAP_SHIFT	XA_CHUNK_SHIFT
 #define RADIX_TREE_MAP_SIZE	(1UL << RADIX_TREE_MAP_SHIFT)
 #define RADIX_TREE_MAP_MASK	(RADIX_TREE_MAP_SIZE-1)
 
-#define RADIX_TREE_TAG_LONGS	\
-	((RADIX_TREE_MAP_SIZE + BITS_PER_LONG - 1) / BITS_PER_LONG)
+#define RADIX_TREE_MAX_TAGS	XA_MAX_TAGS
+#define RADIX_TREE_TAG_LONGS	XA_TAG_LONGS
 
 #define RADIX_TREE_INDEX_BITS  (8 /* CHAR_BIT */ * sizeof(unsigned long))
 #define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \
 					  RADIX_TREE_MAP_SHIFT))
 
-/*
- * @count is the count of every non-NULL element in the ->slots array
- * whether that is a data entry, a retry entry, a user pointer,
- * a sibling entry or a pointer to the next level of the tree.
- * @exceptional is the count of every element in ->slots which is
- * either a data entry or a sibling entry for data.
- */
-struct radix_tree_node {
-	unsigned char	shift;		/* Bits remaining in each slot */
-	unsigned char	offset;		/* Slot offset in parent */
-	unsigned char	count;		/* Total entry count */
-	unsigned char	exceptional;	/* Exceptional entry count */
-	struct radix_tree_node *parent;		/* Used when ascending tree */
-	struct radix_tree_root *root;		/* The tree we belong to */
-	union {
-		struct list_head private_list;	/* For tree user */
-		struct rcu_head	rcu_head;	/* Used when freeing node */
-	};
-	void __rcu	*slots[RADIX_TREE_MAP_SIZE];
-	unsigned long	tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS];
-};
-
 /* The IDR tag is stored in the low bits of xa_flags */
 #define ROOT_IS_IDR	((__force gfp_t)4)
 /* The top bits of xa_flags are used to store the root tags */
diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 43e102616a70..9d0a0a948437 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -195,6 +195,30 @@ static inline void xa_init(struct xarray *xa)
 #endif
 #define XA_CHUNK_SIZE		(1UL << XA_CHUNK_SHIFT)
 #define XA_CHUNK_MASK		(XA_CHUNK_SIZE - 1)
+#define XA_MAX_TAGS		3
+#define XA_TAG_LONGS		DIV_ROUND_UP(XA_CHUNK_SIZE, BITS_PER_LONG)
+
+/*
+ * @count is the count of every non-NULL element in the ->slots array
+ * whether that is a value entry, a retry entry, a user pointer,
+ * a sibling entry or a pointer to the next level of the tree.
+ * @nr_values is the count of every element in ->slots which is
+ * either a value entry or a sibling entry to a value entry.
+ */
+struct xa_node {
+	unsigned char	shift;		/* Bits remaining in each slot */
+	unsigned char	offset;		/* Slot offset in parent */
+	unsigned char	count;		/* Total entry count */
+	unsigned char	nr_values;	/* Value entry count */
+	struct xa_node __rcu *parent;	/* NULL at top of tree */
+	struct xarray	*array;		/* The array we belong to */
+	union {
+		struct list_head private_list;	/* For tree user */
+		struct rcu_head	rcu_head;	/* Used when freeing node */
+	};
+	void __rcu	*slots[XA_CHUNK_SIZE];
+	unsigned long	tags[XA_MAX_TAGS][XA_TAG_LONGS];
+};
 
 /* Private */
 static inline bool xa_is_node(const void *entry)
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 2f57c98c4da6..3764c97a2147 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -260,11 +260,11 @@ static void dump_node(struct radix_tree_node *node, unsigned long index)
 {
 	unsigned long i;
 
-	pr_debug("radix node: %p offset %d indices %lu-%lu parent %p tags %lx %lx %lx shift %d count %d exceptional %d\n",
+	pr_debug("radix node: %p offset %d indices %lu-%lu parent %p tags %lx %lx %lx shift %d count %d nr_values %d\n",
 		node, node->offset, index, index | node_maxindex(node),
 		node->parent,
 		node->tags[0][0], node->tags[1][0], node->tags[2][0],
-		node->shift, node->count, node->exceptional);
+		node->shift, node->count, node->nr_values);
 
 	for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
 		unsigned long first = index | (i << node->shift);
@@ -354,7 +354,7 @@ static struct radix_tree_node *
 radix_tree_node_alloc(gfp_t gfp_mask, struct radix_tree_node *parent,
 			struct radix_tree_root *root,
 			unsigned int shift, unsigned int offset,
-			unsigned int count, unsigned int exceptional)
+			unsigned int count, unsigned int nr_values)
 {
 	struct radix_tree_node *ret = NULL;
 
@@ -401,9 +401,9 @@ radix_tree_node_alloc(gfp_t gfp_mask, struct radix_tree_node *parent,
 		ret->shift = shift;
 		ret->offset = offset;
 		ret->count = count;
-		ret->exceptional = exceptional;
+		ret->nr_values = nr_values;
 		ret->parent = parent;
-		ret->root = root;
+		ret->array = root;
 	}
 	return ret;
 }
@@ -633,8 +633,8 @@ static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp,
 		if (radix_tree_is_internal_node(entry)) {
 			entry_to_node(entry)->parent = node;
 		} else if (xa_is_value(entry)) {
-			/* Moving an exceptional root->xa_head to a node */
-			node->exceptional = 1;
+			/* Moving a value entry root->xa_head to a node */
+			node->nr_values = 1;
 		}
 		/*
 		 * entry was already in the radix tree, so we do not need
@@ -920,12 +920,12 @@ static inline int insert_entries(struct radix_tree_node *node,
 		if (xa_is_node(old))
 			radix_tree_free_nodes(old);
 		if (xa_is_value(old))
-			node->exceptional--;
+			node->nr_values--;
 	}
 	if (node) {
 		node->count += n;
 		if (xa_is_value(item))
-			node->exceptional += n;
+			node->nr_values += n;
 	}
 	return n;
 }
@@ -939,7 +939,7 @@ static inline int insert_entries(struct radix_tree_node *node,
 	if (node) {
 		node->count++;
 		if (xa_is_value(item))
-			node->exceptional++;
+			node->nr_values++;
 	}
 	return 1;
 }
@@ -1073,7 +1073,7 @@ void *radix_tree_lookup(const struct radix_tree_root *root, unsigned long index)
 EXPORT_SYMBOL(radix_tree_lookup);
 
 static inline void replace_sibling_entries(struct radix_tree_node *node,
-				void __rcu **slot, int count, int exceptional)
+				void __rcu **slot, int count, int values)
 {
 #ifdef CONFIG_RADIX_TREE_MULTIORDER
 	unsigned offset = get_slot_offset(node, slot);
@@ -1086,21 +1086,21 @@ static inline void replace_sibling_entries(struct radix_tree_node *node,
 			node->slots[offset] = NULL;
 			node->count--;
 		}
-		node->exceptional += exceptional;
+		node->nr_values += values;
 	}
 #endif
 }
 
 static void replace_slot(void __rcu **slot, void *item,
-		struct radix_tree_node *node, int count, int exceptional)
+		struct radix_tree_node *node, int count, int values)
 {
 	if (WARN_ON_ONCE(radix_tree_is_internal_node(item)))
 		return;
 
-	if (node && (count || exceptional)) {
+	if (node && (count || values)) {
 		node->count += count;
-		node->exceptional += exceptional;
-		replace_sibling_entries(node, slot, count, exceptional);
+		node->nr_values += values;
+		replace_sibling_entries(node, slot, count, values);
 	}
 
 	rcu_assign_pointer(*slot, item);
@@ -1154,17 +1154,17 @@ void __radix_tree_replace(struct radix_tree_root *root,
 			  radix_tree_update_node_t update_node)
 {
 	void *old = rcu_dereference_raw(*slot);
-	int exceptional = !!xa_is_value(item) - !!xa_is_value(old);
+	int values = !!xa_is_value(item) - !!xa_is_value(old);
 	int count = calculate_count(root, node, slot, item, old);
 
 	/*
-	 * This function supports replacing exceptional entries and
+	 * This function supports replacing value entries and
 	 * deleting entries, but that needs accounting against the
 	 * node unless the slot is root->xa_head.
 	 */
 	WARN_ON_ONCE(!node && (slot != (void __rcu **)&root->xa_head) &&
-			(count || exceptional));
-	replace_slot(slot, item, node, count, exceptional);
+			(count || values));
+	replace_slot(slot, item, node, count, values);
 
 	if (!node)
 		return;
@@ -1186,7 +1186,7 @@ void __radix_tree_replace(struct radix_tree_root *root,
  * across slot lookup and replacement.
  *
  * NOTE: This cannot be used to switch between non-entries (empty slots),
- * regular entries, and exceptional entries, as that requires accounting
+ * regular entries, and value entries, as that requires accounting
  * inside the radix tree node. When switching from one type of entry or
  * deleting, use __radix_tree_lookup() and __radix_tree_replace() or
  * radix_tree_iter_replace().
@@ -1294,7 +1294,7 @@ int radix_tree_split(struct radix_tree_root *root, unsigned long index,
 		rcu_assign_pointer(parent->slots[end], RADIX_TREE_RETRY);
 	}
 	rcu_assign_pointer(parent->slots[offset], RADIX_TREE_RETRY);
-	parent->exceptional -= (end - offset);
+	parent->nr_values -= (end - offset);
 
 	if (order == parent->shift)
 		return 0;
@@ -1954,7 +1954,7 @@ static bool __radix_tree_delete(struct radix_tree_root *root,
 				struct radix_tree_node *node, void __rcu **slot)
 {
 	void *old = rcu_dereference_raw(*slot);
-	int exceptional = xa_is_value(old) ? -1 : 0;
+	int values = xa_is_value(old) ? -1 : 0;
 	unsigned offset = get_slot_offset(node, slot);
 	int tag;
 
@@ -1964,7 +1964,7 @@ static bool __radix_tree_delete(struct radix_tree_root *root,
 		for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
 			node_tag_clear(root, node, tag, offset);
 
-	replace_slot(slot, NULL, node, -1, exceptional);
+	replace_slot(slot, NULL, node, -1, values);
 	return node && delete_node(root, node, NULL);
 }
 
diff --git a/mm/workingset.c b/mm/workingset.c
index b5dd3936e697..bad4e58881cd 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -348,7 +348,7 @@ void workingset_update_node(struct radix_tree_node *node)
 	 * already where they should be. The list_empty() test is safe
 	 * as node->private_list is protected by the i_pages lock.
 	 */
-	if (node->count && node->count == node->exceptional) {
+	if (node->count && node->count == node->nr_values) {
 		if (list_empty(&node->private_list))
 			list_lru_add(&shadow_nodes, &node->private_list);
 	} else {
@@ -427,8 +427,8 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
 	 * to reclaim, take the node off-LRU, and drop the lru_lock.
 	 */
 
-	node = container_of(item, struct radix_tree_node, private_list);
-	mapping = container_of(node->root, struct address_space, i_pages);
+	node = container_of(item, struct xa_node, private_list);
+	mapping = container_of(node->array, struct address_space, i_pages);
 
 	/* Coming from the list, invert the lock order */
 	if (!xa_trylock(&mapping->i_pages)) {
@@ -445,25 +445,25 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
 	 * no pages, so we expect to be able to remove them all and
 	 * delete and free the empty node afterwards.
 	 */
-	if (WARN_ON_ONCE(!node->exceptional))
+	if (WARN_ON_ONCE(!node->nr_values))
 		goto out_invalid;
-	if (WARN_ON_ONCE(node->count != node->exceptional))
+	if (WARN_ON_ONCE(node->count != node->nr_values))
 		goto out_invalid;
 	for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
 		if (node->slots[i]) {
 			if (WARN_ON_ONCE(!xa_is_value(node->slots[i])))
 				goto out_invalid;
-			if (WARN_ON_ONCE(!node->exceptional))
+			if (WARN_ON_ONCE(!node->nr_values))
 				goto out_invalid;
 			if (WARN_ON_ONCE(!mapping->nrexceptional))
 				goto out_invalid;
 			node->slots[i] = NULL;
-			node->exceptional--;
+			node->nr_values--;
 			node->count--;
 			mapping->nrexceptional--;
 		}
 	}
-	if (WARN_ON_ONCE(node->exceptional))
+	if (WARN_ON_ONCE(node->nr_values))
 		goto out_invalid;
 	inc_lruvec_page_state(virt_to_page(node), WORKINGSET_NODERECLAIM);
 	__radix_tree_delete_node(&mapping->i_pages, node,
diff --git a/tools/testing/radix-tree/multiorder.c b/tools/testing/radix-tree/multiorder.c
index 3bba18e1ba65..c659056340df 100644
--- a/tools/testing/radix-tree/multiorder.c
+++ b/tools/testing/radix-tree/multiorder.c
@@ -393,7 +393,7 @@ static void multiorder_join2(unsigned order1, unsigned order2)
 	radix_tree_insert(&tree, 1 << order2, xa_mk_value(5));
 	item2 = __radix_tree_lookup(&tree, 1 << order2, &node, NULL);
 	assert(item2 == xa_mk_value(5));
-	assert(node->exceptional == 1);
+	assert(node->nr_values == 1);
 
 	item2 = radix_tree_lookup(&tree, 0);
 	free(item2);
@@ -401,7 +401,7 @@ static void multiorder_join2(unsigned order1, unsigned order2)
 	radix_tree_join(&tree, 0, order1, item1);
 	item2 = __radix_tree_lookup(&tree, 1 << order2, &node, NULL);
 	assert(item2 == item1);
-	assert(node->exceptional == 0);
+	assert(node->nr_values == 0);
 	item_kill_tree(&tree);
 }
 
@@ -409,7 +409,7 @@ static void multiorder_join2(unsigned order1, unsigned order2)
  * This test revealed an accounting bug for inline data entries at one point.
  * Nodes were being freed back into the pool with an elevated exception count
  * by radix_tree_join() and then radix_tree_split() was failing to zero the
- * count of exceptional entries.
+ * count of value entries.
  */
 static void multiorder_join3(unsigned int order)
 {
@@ -433,7 +433,7 @@ static void multiorder_join3(unsigned int order)
 	}
 
 	__radix_tree_lookup(&tree, 0, &node, NULL);
-	assert(node->exceptional == node->count);
+	assert(node->nr_values == node->count);
 
 	item_kill_tree(&tree);
 }
@@ -520,7 +520,7 @@ static void __multiorder_split2(int old_order, int new_order)
 
 	item = __radix_tree_lookup(&tree, 0, &node, NULL);
 	assert(item == xa_mk_value(5));
-	assert(node->exceptional > 0);
+	assert(node->nr_values > 0);
 
 	radix_tree_split(&tree, 0, new_order);
 	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
@@ -530,7 +530,7 @@ static void __multiorder_split2(int old_order, int new_order)
 
 	item = __radix_tree_lookup(&tree, 0, &node, NULL);
 	assert(item != xa_mk_value(5));
-	assert(node->exceptional == 0);
+	assert(node->nr_values == 0);
 
 	item_kill_tree(&tree);
 }
@@ -547,7 +547,7 @@ static void __multiorder_split3(int old_order, int new_order)
 
 	item = __radix_tree_lookup(&tree, 0, &node, NULL);
 	assert(item == xa_mk_value(5));
-	assert(node->exceptional > 0);
+	assert(node->nr_values > 0);
 
 	radix_tree_split(&tree, 0, new_order);
 	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
@@ -556,7 +556,7 @@ static void __multiorder_split3(int old_order, int new_order)
 
 	item = __radix_tree_lookup(&tree, 0, &node, NULL);
 	assert(item == xa_mk_value(7));
-	assert(node->exceptional > 0);
+	assert(node->nr_values > 0);
 
 	item_kill_tree(&tree);
 
@@ -564,7 +564,7 @@ static void __multiorder_split3(int old_order, int new_order)
 
 	item = __radix_tree_lookup(&tree, 0, &node, NULL);
 	assert(item == xa_mk_value(5));
-	assert(node->exceptional > 0);
+	assert(node->nr_values > 0);
 
 	radix_tree_split(&tree, 0, new_order);
 	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
@@ -577,13 +577,13 @@ static void __multiorder_split3(int old_order, int new_order)
 
 	item = __radix_tree_lookup(&tree, 1 << new_order, &node, NULL);
 	assert(item == xa_mk_value(7));
-	assert(node->count == node->exceptional);
+	assert(node->count == node->nr_values);
 	do {
 		node = node->parent;
 		if (!node)
 			break;
 		assert(node->count == 1);
-		assert(node->exceptional == 0);
+		assert(node->nr_values == 0);
 	} while (1);
 
 	item_kill_tree(&tree);
@@ -611,15 +611,15 @@ static void multiorder_account(void)
 
 	__radix_tree_insert(&tree, 1 << 5, 5, xa_mk_value(5));
 	__radix_tree_lookup(&tree, 0, &node, NULL);
-	assert(node->count == node->exceptional * 2);
+	assert(node->count == node->nr_values * 2);
 	radix_tree_delete(&tree, 1 << 5);
-	assert(node->exceptional == 0);
+	assert(node->nr_values == 0);
 
 	__radix_tree_insert(&tree, 1 << 5, 5, xa_mk_value(5));
 	__radix_tree_lookup(&tree, 1 << 5, &node, &slot);
-	assert(node->count == node->exceptional * 2);
+	assert(node->count == node->nr_values * 2);
 	__radix_tree_replace(&tree, node, slot, NULL, NULL);
-	assert(node->exceptional == 0);
+	assert(node->nr_values == 0);
 
 	item_kill_tree(&tree);
 }
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 08/74] xarray: Add documentation
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (6 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 07/74] xarray: Define struct xa_node Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 09/74] xarray: Add XArray load operation Matthew Wilcox
                   ` (66 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

This is documentation on how to use the XArray, not details about its
internal implementation.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Acked-by: Josef Bacik <jbacik@fb.com>
---
 Documentation/core-api/index.rst  |   1 +
 Documentation/core-api/xarray.rst | 395 ++++++++++++++++++++++++++++++
 2 files changed, 396 insertions(+)
 create mode 100644 Documentation/core-api/xarray.rst

diff --git a/Documentation/core-api/index.rst b/Documentation/core-api/index.rst
index f5a66b72f984..e821cf78be3b 100644
--- a/Documentation/core-api/index.rst
+++ b/Documentation/core-api/index.rst
@@ -21,6 +21,7 @@ Core utilities
    local_ops
    workqueue
    genericirq
+   xarray
    flexible-arrays
    librs
    genalloc
diff --git a/Documentation/core-api/xarray.rst b/Documentation/core-api/xarray.rst
new file mode 100644
index 000000000000..1f8556051ddb
--- /dev/null
+++ b/Documentation/core-api/xarray.rst
@@ -0,0 +1,395 @@
+.. SPDX-License-Identifier: CC-BY-SA-4.0
+
+======
+XArray
+======
+
+:Author: Matthew Wilcox
+
+Overview
+========
+
+The XArray is an abstract data type which behaves like a very large array
+of pointers.  It meets many of the same needs as a hash or a conventional
+resizable array.  Unlike a hash, it allows you to sensibly go to the
+next or previous entry in a cache-efficient manner.  In contrast to a
+resizable array, there is no need to copy data or change MMU mappings in
+order to grow the array.  It is more memory-efficient, parallelisable
+and cache friendly than a doubly-linked list.  It takes advantage of
+RCU to perform lookups without locking.
+
+The XArray implementation is efficient when the indices used are densely
+clustered; hashing the object and using the hash as the index will not
+perform well.  The XArray is optimised for small indices, but still has
+good performance with large indices.  If your index can be larger than
+``ULONG_MAX`` then the XArray is not the data type for you.  The most
+important user of the XArray is the page cache.
+
+Each non-``NULL`` entry in the array has three bits associated with it
+called tags.  Each tag may be set or cleared independently of the others.
+You can iterate over entries which are tagged.
+
+Normal pointers may be stored in the XArray directly.  They must be 4-byte
+aligned, which is true for any pointer returned from :c:func:`kmalloc` and
+:c:func:`alloc_page`.  It isn't true for arbitrary user-space pointers,
+nor for function pointers.  You can store pointers to statically allocated
+objects, as long as those objects have an alignment of at least 4.
+
+You can also store integers between 0 and ``LONG_MAX`` in the XArray.
+You must first convert it into an entry using :c:func:`xa_mk_value`.
+When you retrieve an entry from the XArray, you can check whether it is
+a value entry by calling :c:func:`xa_is_value`, and convert it back to
+an integer by calling :c:func:`xa_to_value`.
+
+The XArray does not support storing :c:func:`IS_ERR` pointers as some
+conflict with value entries or internal entries.
+
+An unusual feature of the XArray is the ability to create entries which
+occupy a range of indices.  Once stored to, looking up any index in
+the range will return the same entry as looking up any other index in
+the range.  Setting a tag on one index will set it on all of them.
+Storing to any index will store to all of them.  Multi-index entries can
+be explicitly split into smaller entries, or storing ``NULL`` into any
+entry will cause the XArray to forget about the range.
+
+Normal API
+==========
+
+Start by initialising an XArray, either with :c:func:`DEFINE_XARRAY`
+for statically allocated XArrays or :c:func:`xa_init` for dynamically
+allocated ones.  A freshly-initialised XArray contains a ``NULL``
+pointer at every index.
+
+You can then set entries using :c:func:`xa_store` and get entries
+using :c:func:`xa_load`.  xa_store will overwrite any entry with the
+new entry and return the previous entry stored at that index.  You can
+use :c:func:`xa_erase` instead of calling :c:func:`xa_store` with a
+%NULL entry.  There is no difference between an entry that has never
+been stored to and one that has most recently had ``NULL`` stored to it.
+
+You can conditionally replace an entry at an index by using
+:c:func:`xa_cmpxchg`.  Like :c:func:`cmpxchg`, it will only succeed if
+the entry at that index has the 'old' value.  It also returns the entry
+which was at that index; if it returns the same entry which was passed as
+'old', then :c:func:`xa_cmpxchg` succeeded.
+
+If you want to only store a new entry to an index if the current entry
+at that index is ``NULL``, you can use :c:func:`xa_insert` which
+returns ``-EEXIST`` if the entry is not empty.
+
+Calling :c:func:`xa_reserve` ensures that there is enough memory allocated
+to store an entry at the specified index.  This is not normally needed,
+but some users have a complicated locking scheme.
+
+You can enquire whether a tag is set on an entry by using
+:c:func:`xa_get_tag`.  If the entry is not ``NULL``, you can set a tag
+on it by using :c:func:`xa_set_tag` and remove the tag from an entry by
+calling :c:func:`xa_clear_tag`.  You can ask whether any entry in the
+XArray has a particular tag set by calling :c:func:`xa_tagged`.
+
+You can copy entries out of the XArray into a plain array by calling
+:c:func:`xa_extract`.  Or you can iterate over the present entries in
+the XArray by calling :c:func:`xa_for_each`.  You may prefer to use
+:c:func:`xa_find` or :c:func:`xa_find_after` to move to the next present
+entry in the XArray.
+
+Finally, you can remove all entries from an XArray by calling
+:c:func:`xa_destroy`.  If the XArray entries are pointers, you may wish
+to free the entries first.  You can do this by iterating over all present
+entries in the XArray using the :c:func:`xa_for_each` iterator.
+
+Memory allocation
+-----------------
+
+The :c:func:`xa_store`, :c:func:`xa_cmpxchg`, :c:func:`xa_reserve`
+and :c:func:`xa_insert` functions take a gfp_t parameter in case
+the XArray needs to allocate memory to store this entry.  If the entry
+being stored is ``NULL``, no memory allocation needs to be performed,
+and the GFP flags specified will be ignored.
+
+It is possible for no memory to be allocatable, particularly if you pass
+a restrictive set of GFP flags.  In that case, the functions return a
+special value which can be turned into an errno using :c:func:`xa_err`.
+If you don't need to know exactly which error occurred, using
+:c:func:`xa_is_err` is slightly more efficient.
+
+Locking
+-------
+
+When using the Normal API, you do not have to worry about locking.
+The XArray uses RCU and an internal spinlock to synchronise access:
+
+No lock needed:
+ * :c:func:`xa_empty`
+ * :c:func:`xa_tagged`
+
+Takes RCU read lock:
+ * :c:func:`xa_load`
+ * :c:func:`xa_for_each`
+ * :c:func:`xa_find`
+ * :c:func:`xa_find_after`
+ * :c:func:`xa_extract`
+ * :c:func:`xa_get_tag`
+
+Takes xa_lock internally:
+ * :c:func:`xa_store`
+ * :c:func:`xa_insert`
+ * :c:func:`xa_erase`
+ * :c:func:`xa_cmpxchg`
+ * :c:func:`xa_reserve`
+ * :c:func:`xa_destroy`
+ * :c:func:`xa_set_tag`
+ * :c:func:`xa_clear_tag`
+
+Assumes xa_lock held on entry:
+ * :c:func:`__xa_store`
+ * :c:func:`__xa_insert`
+ * :c:func:`__xa_erase`
+ * :c:func:`__xa_cmpxchg`
+ * :c:func:`__xa_set_tag`
+ * :c:func:`__xa_clear_tag`
+
+If you want to take advantage of the lock to protect the data structures
+that you are storing in the XArray, you can call :c:func:`xa_lock`
+before calling :c:func:`xa_load`, then take a reference count on the
+object you have found before calling :c:func:`xa_unlock`.  This will
+prevent stores from removing the object from the array between looking
+up the object and incrementing the refcount.  You can also use RCU to
+avoid dereferencing freed memory, but an explanation of that is beyond
+the scope of this document.
+
+The XArray does not disable interrupts or softirqs while modifying
+the array.  It is safe to read the XArray from interrupt or softirq
+context as the RCU lock provides enough protection.
+
+If, for example, you want to store entries in the XArray in process
+context and then erase them in softirq context, you can do that this way::
+
+    void foo_init(struct foo *foo)
+    {
+        xa_init_flags(&foo->array, XA_FLAGS_LOCK_BH);
+    }
+
+    int foo_store(struct foo *foo, unsigned long index, void *entry)
+    {
+        int err;
+
+        xa_lock_bh(&foo->array);
+        err = xa_err(__xa_store(&foo->array, index, entry, GFP_KERNEL));
+        if (!err)
+            foo->count++;
+        xa_unlock_bh(&foo->array);
+        return err;
+    }
+
+    /* foo_erase() is only called from softirq context */
+    void foo_erase(struct foo *foo, unsigned long index)
+    {
+        xa_lock(&foo->array);
+        __xa_erase(&foo->array, index);
+        foo->count--;
+        xa_unlock(&foo->array);
+    }
+
+If you are going to modify the XArray from interrupt or softirq context,
+you need to initialise the array using :c:func:`xa_init_flags`, passing
+``XA_FLAGS_LOCK_IRQ`` or ``XA_FLAGS_LOCK_BH``.
+
+The above example also shows a common pattern of wanting to extend the
+coverage of the xa_lock on the store side to protect some statistics
+associated with the array.
+
+Sharing the XArray with interrupt context is also possible, either
+using :c:func:`xa_lock_irqsave` in both the interrupt handler and process
+context, or :c:func:`xa_lock_irq` in process context and :c:func:`xa_lock`
+in the interrupt handler.
+
+Sometimes you need to protect access to the XArray with a mutex because
+that lock sits above another mutex in the locking hierarchy.  That does
+not entitle you to use functions like :c:func:`__xa_erase` without taking
+the xa_lock; the xa_lock is used for lockdep validation and will be used
+for other purposes in the future.
+
+The :c:func:`__xa_set_tag` and :c:func:`__xa_clear_tag` functions are also
+available for situations where you look up an entry and want to atomically
+set or clear a tag.  It may be more efficient to use the advanced API
+in this case, as it will save you from walking the tree twice.
+
+Advanced API
+============
+
+The advanced API offers more flexibility and better performance at the
+cost of an interface which can be harder to use and has fewer safeguards.
+No locking is done for you by the advanced API, and you are required
+to use the xa_lock while modifying the array.  You can choose whether
+to use the xa_lock or the RCU lock while doing read-only operations on
+the array.  You can mix advanced and normal operations on the same array;
+indeed the normal API is implemented in terms of the advanced API.  The
+advanced API is only available to modules with a GPL-compatible license.
+
+The advanced API is based around the xa_state.  This is an opaque data
+structure which you declare on the stack using the :c:func:`XA_STATE`
+macro.  This macro initialises the xa_state ready to start walking
+around the XArray.  It is used as a cursor to maintain the position
+in the XArray and let you compose various operations together without
+having to restart from the top every time.
+
+The xa_state is also used to store errors.  You can call
+:c:func:`xas_error` to retrieve the error.  All operations check whether
+the xa_state is in an error state before proceeding, so there's no need
+for you to check for an error after each call; you can make multiple
+calls in succession and only check at a convenient point.  The only
+errors currently generated by the xarray code itself are %ENOMEM and
+%EINVAL, but it supports arbitrary errors in case you want to call
+:c:func:`xas_set_err` yourself.
+
+If the xa_state is holding an %ENOMEM error, calling :c:func:`xas_nomem`
+will attempt to allocate more memory using the specified gfp flags and
+cache it in the xa_state for the next attempt.  The idea is that you take
+the xa_lock, attempt the operation and drop the lock.  The operation
+attempts to allocate memory while holding the lock, but it is more
+likely to fail.  Once you have dropped the lock, :c:func:`xas_nomem`
+can try harder to allocate more memory.  It will return ``true`` if it
+is worth retrying the operation (i.e. that there was a memory error *and*
+more memory was allocated).  If it has previously allocated memory, and
+that memory wasn't used, and there is no error (or some error that isn't
+%ENOMEM), then it will free the memory previously allocated.
+
+Internal Entries
+----------------
+
+The XArray reserves some entries for its own purposes.  These are never
+exposed through the normal API, but when using the advanced API, it's
+possible to see them.  Usually the best way to handle them is to pass them
+to :c:func:`xas_retry`, and retry the operation if it returns ``true``.
+
+.. flat-table::
+   :widths: 1 1 6
+
+   * - Name
+     - Test
+     - Usage
+
+   * - Node
+     - :c:func:`xa_is_node`
+     - An XArray node.  May be visible when using a multi-index xa_state.
+
+   * - Sibling
+     - :c:func:`xa_is_sibling`
+     - A non-canonical entry for a multi-index entry.  The value indicates
+       which slot in this node has the canonical entry.
+
+   * - Retry
+     - :c:func:`xa_is_retry`
+     - This entry is currently being modified by a thread which has the
+       xa_lock.  The node containing this entry may be freed at the end
+       of this RCU period.  You should restart the lookup from the head
+       of the array.
+
+Other internal entries may be added in the future.  As far as possible, they
+will be handled by :c:func:`xas_retry`.
+
+Additional functionality
+------------------------
+
+The :c:func:`xas_create_range` function allocates all the necessary memory
+to store every entry in a range.  It will set ENOMEM in the xa_state if
+it cannot allocate memory.
+
+You can use :c:func:`xas_init_tags` to reset the tags on an entry
+to their default state.  This is usually all tags clear, unless the
+XArray is marked with ``XA_FLAGS_TRACK_FREE``, in which case tag 0 is set
+and all other tags are clear.  Replacing one entry with another using
+:c:func:`xas_store` will not reset the tags on that entry; if you want
+the tags reset, you should do that explicitly.
+
+The :c:func:`xas_load` will walk the xa_state as close to the entry
+as it can.  If you know the xa_state has already been walked to the
+entry and need to check that the entry hasn't changed, you can use
+:c:func:`xas_reload` to save a function call.
+
+If you need to move to a different index in the XArray, call
+:c:func:`xas_set`.  This resets the cursor to the top of the tree, which
+will generally make the next operation walk the cursor to the desired
+spot in the tree.  If you want to move to the next or previous index,
+call :c:func:`xas_next` or :c:func:`xas_prev`.  Setting the index does
+not walk the cursor around the array so does not require a lock to be
+held, while moving to the next or previous index does.
+
+You can search for the next present entry using :c:func:`xas_find`.  This
+is the equivalent of both :c:func:`xa_find` and :c:func:`xa_find_after`;
+if the cursor has been walked to an entry, then it will find the next
+entry after the one currently referenced.  If not, it will return the
+entry at the index of the xa_state.  Using :c:func:`xas_next_entry` to
+move to the next present entry instead of :c:func:`xas_find` will save
+a function call in the majority of cases at the expense of emitting more
+inline code.
+
+The :c:func:`xas_find_tagged` function is similar.  If the xa_state has
+not been walked, it will return the entry at the index of the xa_state,
+if it is tagged.  Otherwise, it will return the first tagged entry after
+the entry referenced by the xa_state.  The :c:func:`xas_next_tagged`
+function is the equivalent of :c:func:`xas_next_entry`.
+
+When iterating over a range of the XArray using :c:func:`xas_for_each`
+or :c:func:`xas_for_each_tagged`, it may be necessary to temporarily stop
+the iteration.  The :c:func:`xas_pause` function exists for this purpose.
+After you have done the necessary work and wish to resume, the xa_state
+is in an appropriate state to continue the iteration after the entry
+you last processed.  If you have interrupts disabled while iterating,
+then it is good manners to pause the iteration and reenable interrupts
+every ``XA_CHECK_SCHED`` entries.
+
+The :c:func:`xas_get_tag`, :c:func:`xas_set_tag` and
+:c:func:`xas_clear_tag` functions require the xa_state cursor to have
+been moved to the appropriate location in the xarray; they will do
+nothing if you have called :c:func:`xas_pause` or :c:func:`xas_set`
+immediately before.
+
+You can call :c:func:`xas_set_update` to have a callback function
+called each time the XArray updates a node.  This is used by the page
+cache workingset code to maintain its list of nodes which contain only
+shadow entries.
+
+Multi-Index Entries
+-------------------
+
+The XArray has the ability to tie multiple indices together so that
+operations on one index affect all indices.  For example, storing into
+any index will change the value of the entry retrieved from any index.
+Setting or clearing a tag on any index will set or clear the tag
+on every index that is tied together.  The current implementation
+only allows tying ranges which are aligned powers of two together;
+eg indices 64-127 may be tied together, but 2-6 may not be.  This may
+save substantial quantities of memory; for example tying 512 entries
+together will save over 4kB.
+
+You can create a multi-index entry by using :c:func:`XA_STATE_ORDER`
+or :c:func:`xas_set_order` followed by a call to :c:func:`xas_store`.
+Calling :c:func:`xas_load` with a multi-index xa_state will walk
+the xa_state to the right location in the tree, but the return
+value is not meaningful, potentially being an internal entry.
+The :c:func:`xas_for_each_conflict` iterator will iterate over every
+entry which overlaps the specified range.
+
+If :c:func:`xas_load` encounters a multi-index entry, the xa_index
+in the xa_state will not be changed.  When iterating over an XArray
+or calling :c:func:`xas_find`, if the initial index is in the middle
+of a multi-index entry, it will not be altered.  Subsequent calls
+or iterations will move the index to the first index in the range.
+Each entry will only be returned once, no matter how many indices it
+occupies.
+
+Using :c:func:`xas_next` or :c:func:`xas_prev` with a multi-index xa_state
+is not supported.  Using either of these functions on a multi-index entry
+will reveal sibling entries; these should be skipped over by the caller.
+
+Storing ``NULL`` into any index of a multi-index entry will set the entry
+at every index to ``NULL`` and dissolve the tie.  Splitting a multi-index
+entry into entries occupying smaller ranges is not yet supported.
+
+Functions and structures
+========================
+
+.. kernel-doc:: include/linux/xarray.h
+.. kernel-doc:: lib/xarray.c
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 09/74] xarray: Add XArray load operation
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (7 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 08/74] xarray: Add documentation Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 10/74] xarray: Add XArray tags Matthew Wilcox
                   ` (65 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

The xa_load function brings with it a lot of infrastructure; xa_empty(),
xa_is_err(), and large chunks of the XArray advanced API that are used
to implement xa_load.

As the test-suite demonstrates, it is possible to use the XArray functions
on a radix tree.  The radix tree functions depend on the GFP flags being
stored in the root of the tree, so it's not possible to use the radix
tree functions on an XArray.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/xarray.h                    | 336 ++++++++++++++++++++++
 lib/Kconfig.debug                         |   3 +
 lib/Makefile                              |   1 +
 lib/radix-tree.c                          |  43 ---
 lib/test_xarray.c                         |  84 ++++++
 lib/xarray.c                              | 192 +++++++++++++
 tools/include/linux/kernel.h              |   1 +
 tools/testing/radix-tree/.gitignore       |   1 +
 tools/testing/radix-tree/Makefile         |   6 +-
 tools/testing/radix-tree/linux/kernel.h   |   1 +
 tools/testing/radix-tree/linux/rcupdate.h |   2 +
 tools/testing/radix-tree/main.c           |   1 +
 tools/testing/radix-tree/test.h           |   1 +
 tools/testing/radix-tree/xarray.c         |  26 ++
 14 files changed, 653 insertions(+), 45 deletions(-)
 create mode 100644 lib/test_xarray.c

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 9d0a0a948437..074ba6db110f 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -12,6 +12,8 @@
 #include <linux/bug.h>
 #include <linux/compiler.h>
 #include <linux/kconfig.h>
+#include <linux/kernel.h>
+#include <linux/rcupdate.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
 
@@ -30,6 +32,10 @@
  *
  * 0-62: Sibling entries
  * 256: Retry entry
+ *
+ * Errors are also represented as internal entries, but use the negative
+ * space (-4094 to -2).  They're never stored in the slots array; only
+ * returned by the normal API.
  */
 
 #define BITS_PER_XA_VALUE	(BITS_PER_LONG - 1)
@@ -107,6 +113,42 @@ static inline bool xa_is_internal(const void *entry)
 	return ((unsigned long)entry & 3) == 2;
 }
 
+/**
+ * xa_is_err() - Report whether an XArray operation returned an error
+ * @entry: Result from calling an XArray function
+ *
+ * If an XArray operation cannot complete an operation, it will return
+ * a special value indicating an error.  This function tells you
+ * whether an error occurred; xa_err() tells you which error occurred.
+ *
+ * Context: Any context.
+ * Return: %true if the entry indicates an error.
+ */
+static inline bool xa_is_err(const void *entry)
+{
+	return unlikely(xa_is_internal(entry));
+}
+
+/**
+ * xa_err() - Turn an XArray result into an errno.
+ * @entry: Result from calling an XArray function.
+ *
+ * If an XArray operation cannot complete an operation, it will return
+ * a special pointer value which encodes an errno.  This function extracts
+ * the errno from the pointer value, or returns 0 if the pointer does not
+ * represent an errno.
+ *
+ * Context: Any context.
+ * Return: A negative errno or 0.
+ */
+static inline int xa_err(void *entry)
+{
+	/* xa_to_internal() would not do sign extension. */
+	if (xa_is_err(entry))
+		return (long)entry >> 2;
+	return 0;
+}
+
 /**
  * struct xarray - The anchor of the XArray.
  * @xa_lock: Lock that protects the contents of the XArray.
@@ -152,6 +194,7 @@ struct xarray {
 			struct xarray name = XARRAY_INIT_FLAGS(name, flags)
 
 void xa_init_flags(struct xarray *, gfp_t flags);
+void *xa_load(struct xarray *, unsigned long index);
 
 /**
  * xa_init() - Initialise an empty XArray.
@@ -166,6 +209,18 @@ static inline void xa_init(struct xarray *xa)
 	xa_init_flags(xa, 0);
 }
 
+/**
+ * xa_empty() - Determine if an array has any present entries.
+ * @xa: XArray.
+ *
+ * Context: Any context.
+ * Return: %true if the array contains only NULL pointers.
+ */
+static inline bool xa_empty(const struct xarray *xa)
+{
+	return xa->xa_head == NULL;
+}
+
 #define xa_trylock(xa)		spin_trylock(&(xa)->xa_lock)
 #define xa_lock(xa)		spin_lock(&(xa)->xa_lock)
 #define xa_unlock(xa)		spin_unlock(&(xa)->xa_lock)
@@ -220,6 +275,65 @@ struct xa_node {
 	unsigned long	tags[XA_MAX_TAGS][XA_TAG_LONGS];
 };
 
+void xa_dump(const struct xarray *);
+void xa_dump_node(const struct xa_node *);
+
+#ifdef XA_DEBUG
+#define XA_BUG_ON(xa, x) do {					\
+		if (x) {					\
+			xa_dump(xa);				\
+			BUG();					\
+		}						\
+	} while (0)
+#define XA_NODE_BUG_ON(node, x) do {				\
+		if (x) {					\
+			if (node) xa_dump_node(node);		\
+			BUG();					\
+		}						\
+	} while (0)
+#else
+#define XA_BUG_ON(xa, x)	do { } while (0)
+#define XA_NODE_BUG_ON(node, x)	do { } while (0)
+#endif
+
+/* Private */
+static inline void *xa_head(const struct xarray *xa)
+{
+	return rcu_dereference_check(xa->xa_head,
+						lockdep_is_held(&xa->xa_lock));
+}
+
+/* Private */
+static inline void *xa_head_locked(const struct xarray *xa)
+{
+	return rcu_dereference_protected(xa->xa_head,
+						lockdep_is_held(&xa->xa_lock));
+}
+
+/* Private */
+static inline void *xa_entry(const struct xarray *xa,
+				const struct xa_node *node, unsigned int offset)
+{
+	XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
+	return rcu_dereference_check(node->slots[offset],
+						lockdep_is_held(&xa->xa_lock));
+}
+
+/* Private */
+static inline void *xa_entry_locked(const struct xarray *xa,
+				const struct xa_node *node, unsigned int offset)
+{
+	XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
+	return rcu_dereference_protected(node->slots[offset],
+						lockdep_is_held(&xa->xa_lock));
+}
+
+/* Private */
+static inline struct xa_node *xa_to_node(const void *entry)
+{
+	return (struct xa_node *)((unsigned long)entry - 2);
+}
+
 /* Private */
 static inline bool xa_is_node(const void *entry)
 {
@@ -253,4 +367,226 @@ static inline bool xa_is_sibling(const void *entry)
 
 #define XA_RETRY_ENTRY		xa_mk_internal(256)
 
+/**
+ * xa_is_retry() - Is the entry a retry entry?
+ * @entry: Entry retrieved from the XArray
+ *
+ * Return: %true if the entry is a retry entry.
+ */
+static inline bool xa_is_retry(const void *entry)
+{
+	return unlikely(entry == XA_RETRY_ENTRY);
+}
+
+/**
+ * typedef xa_update_node_t - A callback function from the XArray.
+ * @node: The node which is being processed
+ *
+ * This function is called every time the XArray updates the count of
+ * present and value entries in a node.  It allows advanced users to
+ * maintain the private_list in the node.
+ *
+ * Context: The xa_lock is held and interrupts may be disabled.
+ *	    Implementations should not drop the xa_lock, nor re-enable
+ *	    interrupts.
+ */
+typedef void (*xa_update_node_t)(struct xa_node *node);
+
+/*
+ * The xa_state is opaque to its users.  It contains various different pieces
+ * of state involved in the current operation on the XArray.  It should be
+ * declared on the stack and passed between the various internal routines.
+ * The various elements in it should not be accessed directly, but only
+ * through the provided accessor functions.  The below documentation is for
+ * the benefit of those working on the code, not for users of the XArray.
+ *
+ * @xa_node usually points to the xa_node containing the slot we're operating
+ * on (and @xa_offset is the offset in the slots array).  If there is a
+ * single entry in the array at index 0, there are no allocated xa_nodes to
+ * point to, and so we store %NULL in @xa_node.  @xa_node is set to
+ * the value %XAS_RESTART if the xa_state is not walked to the correct
+ * position in the tree of nodes for this operation.  If an error occurs
+ * during an operation, it is set to an %XAS_ERROR value.  If we run off the
+ * end of the allocated nodes, it is set to %XAS_BOUNDS.
+ */
+struct xa_state {
+	struct xarray *xa;
+	unsigned long xa_index;
+	unsigned char xa_shift;
+	unsigned char xa_sibs;
+	unsigned char xa_offset;
+	unsigned char xa_pad;		/* Helps gcc generate better code */
+	struct xa_node *xa_node;
+	struct xa_node *xa_alloc;
+	xa_update_node_t xa_update;
+};
+
+/*
+ * We encode errnos in the xas->xa_node.  If an error has happened, we need to
+ * drop the lock to fix it, and once we've done so the xa_state is invalid.
+ */
+#define XA_ERROR(errno) ((struct xa_node *)(((unsigned long)errno << 2) | 2UL))
+#define XAS_BOUNDS	((struct xa_node *)1UL)
+#define XAS_RESTART	((struct xa_node *)3UL)
+
+#define __XA_STATE(array, index, shift, sibs)  {	\
+	.xa = array,					\
+	.xa_index = index,				\
+	.xa_shift = shift,				\
+	.xa_sibs = sibs,				\
+	.xa_offset = 0,					\
+	.xa_pad = 0,					\
+	.xa_node = XAS_RESTART,				\
+	.xa_alloc = NULL,				\
+	.xa_update = NULL				\
+}
+
+/**
+ * XA_STATE() - Declare an XArray operation state.
+ * @name: Name of this operation state (usually xas).
+ * @array: Array to operate on.
+ * @index: Initial index of interest.
+ *
+ * Declare and initialise an xa_state on the stack.
+ */
+#define XA_STATE(name, array, index)				\
+	struct xa_state name = __XA_STATE(array, index, 0, 0)
+
+/**
+ * XA_STATE_ORDER() - Declare an XArray operation state.
+ * @name: Name of this operation state (usually xas).
+ * @array: Array to operate on.
+ * @index: Initial index of interest.
+ * @order: Order of entry.
+ *
+ * Declare and initialise an xa_state on the stack.  This variant of
+ * XA_STATE() allows you to specify the 'order' of the element you
+ * want to operate on.`
+ */
+#define XA_STATE_ORDER(name, array, index, order)		\
+	struct xa_state name = __XA_STATE(array,		\
+			(index >> order) << order,		\
+			order - (order % XA_CHUNK_SHIFT),	\
+			(1U << (order % XA_CHUNK_SHIFT)) - 1)
+
+#define xas_tagged(xas, tag)	xa_tagged((xas)->xa, (tag))
+#define xas_trylock(xas)	xa_trylock((xas)->xa)
+#define xas_lock(xas)		xa_lock((xas)->xa)
+#define xas_unlock(xas)		xa_unlock((xas)->xa)
+#define xas_lock_bh(xas)	xa_lock_bh((xas)->xa)
+#define xas_unlock_bh(xas)	xa_unlock_bh((xas)->xa)
+#define xas_lock_irq(xas)	xa_lock_irq((xas)->xa)
+#define xas_unlock_irq(xas)	xa_unlock_irq((xas)->xa)
+#define xas_lock_irqsave(xas, flags) \
+				xa_lock_irqsave((xas)->xa, flags)
+#define xas_unlock_irqrestore(xas, flags) \
+				xa_unlock_irqrestore((xas)->xa, flags)
+
+/**
+ * xas_error() - Return an errno stored in the xa_state.
+ * @xas: XArray operation state.
+ *
+ * Return: 0 if no error has been noted.  A negative errno if one has.
+ */
+static inline int xas_error(const struct xa_state *xas)
+{
+	return xa_err(xas->xa_node);
+}
+
+/**
+ * xas_set_err() - Note an error in the xa_state.
+ * @xas: XArray operation state.
+ * @err: Negative error number.
+ *
+ * Only call this function with a negative @err; zero or positive errors
+ * will probably not behave the way you think they should.  If you want
+ * to clear the error from an xa_state, use xas_reset().
+ */
+static inline void xas_set_err(struct xa_state *xas, long err)
+{
+	xas->xa_node = XA_ERROR(err);
+}
+
+/**
+ * xas_invalid() - Is the xas in a retry or error state?
+ * @xas: XArray operation state.
+ *
+ * Return: %true if the xas cannot be used for operations.
+ */
+static inline bool xas_invalid(const struct xa_state *xas)
+{
+	return (unsigned long)xas->xa_node & 3;
+}
+
+/**
+ * xas_valid() - Is the xas a valid cursor into the array?
+ * @xas: XArray operation state.
+ *
+ * Return: %true if the xas can be used for operations.
+ */
+static inline bool xas_valid(const struct xa_state *xas)
+{
+	return !xas_invalid(xas);
+}
+
+/**
+ * xas_reset() - Reset an XArray operation state.
+ * @xas: XArray operation state.
+ *
+ * Resets the error or walk state of the @xas so future walks of the
+ * array will start from the root.  Use this if you have dropped the
+ * xarray lock and want to reuse the xa_state.
+ *
+ * Context: Any context.
+ */
+static inline void xas_reset(struct xa_state *xas)
+{
+	xas->xa_node = XAS_RESTART;
+}
+
+/**
+ * xas_retry() - Handle a retry entry.
+ * @xas: XArray operation state.
+ * @entry: Entry from xarray.
+ *
+ * An RCU-protected read may see a retry entry as a side-effect of a
+ * simultaneous modification.  This function sets up the @xas to retry
+ * the walk from the head of the array.
+ *
+ * Context: Any context.
+ * Return: true if the operation needs to be retried.
+ */
+static inline bool xas_retry(struct xa_state *xas, const void *entry)
+{
+	if (!xa_is_retry(entry))
+		return false;
+	xas_reset(xas);
+	return true;
+}
+
+void *xas_load(struct xa_state *);
+
+/**
+ * xas_reload() - Refetch an entry from the xarray.
+ * @xas: XArray operation state.
+ *
+ * Use this function to check that a previously loaded entry still has
+ * the same value.  This is useful for the lockless pagecache lookup where
+ * we walk the array with only the RCU lock to protect us, lock the page,
+ * then check that the page hasn't moved since we looked it up.
+ *
+ * The caller guarantees that @xas is still valid.  If it may be in an
+ * error or restart state, call xas_load() instead.
+ *
+ * Return: The entry at this location in the xarray.
+ */
+static inline void *xas_reload(struct xa_state *xas)
+{
+	struct xa_node *node = xas->xa_node;
+
+	if (node)
+		return xa_entry(xas->xa, node, xas->xa_offset);
+	return xa_head(xas->xa);
+}
+
 #endif /* _LINUX_XARRAY_H */
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 8838d1158d19..df1ea92d924c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1802,6 +1802,9 @@ config TEST_BITMAP
 
 	  If unsure, say N.
 
+config TEST_XARRAY
+	tristate "Test the XArray code at runtime"
+
 config TEST_UUID
 	tristate "Test functions located in the uuid module at runtime"
 
diff --git a/lib/Makefile b/lib/Makefile
index 507e5df0512d..f998889e72e6 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -69,6 +69,7 @@ obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_key_base.o
 obj-$(CONFIG_TEST_PRINTF) += test_printf.o
 obj-$(CONFIG_TEST_BITMAP) += test_bitmap.o
 obj-$(CONFIG_TEST_UUID) += test_uuid.o
+obj-$(CONFIG_TEST_XARRAY) += test_xarray.o
 obj-$(CONFIG_TEST_PARMAN) += test_parman.o
 obj-$(CONFIG_TEST_KMOD) += test_kmod.o
 obj-$(CONFIG_TEST_DEBUG_VIRTUAL) += test_debug_virtual.o
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 3764c97a2147..d20b625d963e 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -256,49 +256,6 @@ static unsigned long next_index(unsigned long index,
 }
 
 #ifndef __KERNEL__
-static void dump_node(struct radix_tree_node *node, unsigned long index)
-{
-	unsigned long i;
-
-	pr_debug("radix node: %p offset %d indices %lu-%lu parent %p tags %lx %lx %lx shift %d count %d nr_values %d\n",
-		node, node->offset, index, index | node_maxindex(node),
-		node->parent,
-		node->tags[0][0], node->tags[1][0], node->tags[2][0],
-		node->shift, node->count, node->nr_values);
-
-	for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
-		unsigned long first = index | (i << node->shift);
-		unsigned long last = first | ((1UL << node->shift) - 1);
-		void *entry = node->slots[i];
-		if (!entry)
-			continue;
-		if (entry == RADIX_TREE_RETRY) {
-			pr_debug("radix retry offset %ld indices %lu-%lu parent %p\n",
-					i, first, last, node);
-		} else if (!radix_tree_is_internal_node(entry)) {
-			pr_debug("radix entry %p offset %ld indices %lu-%lu parent %p\n",
-					entry, i, first, last, node);
-		} else if (xa_is_sibling(entry)) {
-			pr_debug("radix sblng %p offset %ld indices %lu-%lu parent %p val %p\n",
-					entry, i, first, last, node,
-					node->slots[xa_to_sibling(entry)]);
-		} else {
-			dump_node(entry_to_node(entry), first);
-		}
-	}
-}
-
-/* For debug */
-static void radix_tree_dump(struct radix_tree_root *root)
-{
-	pr_debug("radix root: %p xa_head %p tags %x\n",
-			root, root->xa_head,
-			root->xa_flags >> ROOT_TAG_SHIFT);
-	if (!radix_tree_is_internal_node(root->xa_head))
-		return;
-	dump_node(entry_to_node(root->xa_head), 0);
-}
-
 static void dump_ida_node(void *entry, unsigned long index)
 {
 	unsigned long i;
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
new file mode 100644
index 000000000000..e38dd42a3f7c
--- /dev/null
+++ b/lib/test_xarray.c
@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * test_xarray.c: Test the XArray API
+ * Copyright (c) 2017-2018 Microsoft Corporation
+ * Author: Matthew Wilcox <willy@infradead.org>
+ */
+
+#include <linux/xarray.h>
+#include <linux/module.h>
+
+static unsigned int tests_run;
+static unsigned int tests_passed;
+
+#ifndef XA_DEBUG
+# ifdef __KERNEL__
+void xa_dump(const struct xarray *xa) { }
+# endif
+#undef XA_BUG_ON
+#define XA_BUG_ON(xa, x) do {					\
+	tests_run++;						\
+	if (x) {						\
+		xa_dump(xa);					\
+		dump_stack();					\
+	} else {						\
+		tests_passed++;					\
+	}							\
+} while (0)
+#endif
+
+static void *xa_store_value(struct xarray *xa, unsigned long index, gfp_t gfp)
+{
+	radix_tree_insert(xa, index, xa_mk_value(index));
+	return NULL;
+}
+
+static void xa_erase_value(struct xarray *xa, unsigned long index)
+{
+	radix_tree_delete(xa, index);
+}
+
+static void check_xa_load(struct xarray *xa)
+{
+	unsigned long i, j;
+
+	for (i = 0; i < 1024; i++) {
+		for (j = 0; j < 1024; j++) {
+			void *entry = xa_load(xa, j);
+			if (j < i)
+				XA_BUG_ON(xa, xa_to_value(entry) != j);
+			else
+				XA_BUG_ON(xa, entry);
+		}
+		XA_BUG_ON(xa, xa_store_value(xa, i, GFP_KERNEL) != NULL);
+	}
+
+	for (i = 0; i < 1024; i++) {
+		for (j = 0; j < 1024; j++) {
+			void *entry = xa_load(xa, j);
+			if (j >= i)
+				XA_BUG_ON(xa, xa_to_value(entry) != j);
+			else
+				XA_BUG_ON(xa, entry);
+		}
+		xa_erase_value(xa, i);
+	}
+	XA_BUG_ON(xa, !xa_empty(xa));
+}
+
+static int xarray_checks(void)
+{
+	RADIX_TREE(array, GFP_KERNEL);
+
+	check_xa_load(&array);
+
+	printk("XArray: %u of %u tests passed\n", tests_passed, tests_run);
+	return (tests_run != tests_passed) ? 0 : -EINVAL;
+}
+
+static void xarray_exit(void)
+{
+}
+
+module_init(xarray_checks);
+module_exit(xarray_exit);
diff --git a/lib/xarray.c b/lib/xarray.c
index 3da0346f8f8f..4d291965e590 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -24,6 +24,101 @@
  * @entry refers to something stored in a slot in the xarray
  */
 
+/* extracts the offset within this node from the index */
+static unsigned int get_offset(unsigned long index, struct xa_node *node)
+{
+	return (index >> node->shift) & XA_CHUNK_MASK;
+}
+
+/* move the index either forwards (find) or backwards (sibling slot) */
+static void xas_move_index(struct xa_state *xas, unsigned long offset)
+{
+	unsigned int shift = xas->xa_node->shift;
+	xas->xa_index &= ~XA_CHUNK_MASK << shift;
+	xas->xa_index += offset << shift;
+}
+
+static void *set_bounds(struct xa_state *xas)
+{
+	xas->xa_node = XAS_BOUNDS;
+	return NULL;
+}
+
+/*
+ * Starts a walk.  If the @xas is already valid, we assume that it's on
+ * the right path and just return where we've got to.  If we're in an
+ * error state, return NULL.  If the index is outside the current scope
+ * of the xarray, return NULL without changing @xas->xa_node.  Otherwise
+ * set @xas->xa_node to NULL and return the current head of the array.
+ */
+static void *xas_start(struct xa_state *xas)
+{
+	void *entry;
+
+	if (xas_valid(xas))
+		return xas_reload(xas);
+	if (xas_error(xas))
+		return NULL;
+
+	entry = xa_head(xas->xa);
+	if (!xa_is_node(entry)) {
+		if (xas->xa_index)
+			return set_bounds(xas);
+	} else {
+		if ((xas->xa_index >> xa_to_node(entry)->shift) > XA_CHUNK_MASK)
+			return set_bounds(xas);
+	}
+
+	xas->xa_node = NULL;
+	return entry;
+}
+
+static void *xas_descend(struct xa_state *xas, struct xa_node *node)
+{
+	unsigned int offset = get_offset(xas->xa_index, node);
+	void *entry = xa_entry(xas->xa, node, offset);
+
+	xas->xa_node = node;
+	if (xa_is_sibling(entry)) {
+		offset = xa_to_sibling(entry);
+		entry = xa_entry(xas->xa, node, offset);
+		xas_move_index(xas, offset);
+	}
+
+	xas->xa_offset = offset;
+	return entry;
+}
+
+/**
+ * xas_load() - Load an entry from the XArray (advanced).
+ * @xas: XArray operation state.
+ *
+ * Usually walks the @xas to the appropriate state to load the entry
+ * stored at xa_index.  However, it will do nothing and return %NULL if
+ * @xas is in an error state.  xas_load() will never expand the tree.
+ *
+ * If the xa_state is set up to operate on a multi-index entry, xas_load()
+ * may return %NULL or an internal entry, even if there are entries
+ * present within the range specified by @xas.
+ *
+ * Context: Any context.  The caller should hold the xa_lock or the RCU lock.
+ * Return: Usually an entry in the XArray, but see description for exceptions.
+ */
+void *xas_load(struct xa_state *xas)
+{
+	void *entry = xas_start(xas);
+
+	while (xa_is_node(entry)) {
+		struct xa_node *node = xa_to_node(entry);
+
+		if (xas->xa_shift > node->shift)
+			break;
+		entry = xas_descend(xas, node);
+	}
+	return entry;
+}
+EXPORT_SYMBOL_GPL(xas_load);
+
 /**
  * xa_init_flags() - Initialise an empty XArray with flags.
  * @xa: XArray.
@@ -42,3 +137,100 @@ void xa_init_flags(struct xarray *xa, gfp_t flags)
 	xa->xa_head = NULL;
 }
 EXPORT_SYMBOL(xa_init_flags);
+
+/**
+ * xa_load() - Load an entry from an XArray.
+ * @xa: XArray.
+ * @index: index into array.
+ *
+ * Context: Any context.  Takes and releases the RCU lock.
+ * Return: The entry at @index in @xa.
+ */
+void *xa_load(struct xarray *xa, unsigned long index)
+{
+	XA_STATE(xas, xa, index);
+	void *entry;
+
+	rcu_read_lock();
+	do {
+		entry = xas_load(&xas);
+	} while (xas_retry(&xas, entry));
+	rcu_read_unlock();
+
+	return entry;
+}
+EXPORT_SYMBOL(xa_load);
+
+#ifdef XA_DEBUG
+void xa_dump_node(const struct xa_node *node)
+{
+	unsigned i, j;
+
+	if (!node)
+		return;
+	if ((unsigned long)node & 3) {
+		pr_cont("node %px\n", node);
+		return;
+	}
+
+	pr_cont("node %px %s %d parent %px shift %d count %d values %d "
+		"array %px list %px %px tags",
+		node, node->parent ? "offset" : "max", node->offset,
+		node->parent, node->shift, node->count, node->nr_values,
+		node->array, node->private_list.prev, node->private_list.next);
+	for (i = 0; i < XA_MAX_TAGS; i++)
+		for (j = 0; j < XA_TAG_LONGS; j++)
+			pr_cont(" %lx", node->tags[i][j]);
+	pr_cont("\n");
+}
+
+void xa_dump_index(unsigned long index, unsigned int shift)
+{
+	if (!shift)
+		pr_info("%lu: ", index);
+	else if (shift >= BITS_PER_LONG)
+		pr_info("0-%lu: ", ~0UL);
+	else
+		pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1));
+}
+
+void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift)
+{
+	if (!entry)
+		return;
+
+	xa_dump_index(index, shift);
+
+	if (xa_is_node(entry)) {
+		unsigned long i;
+		struct xa_node *node = xa_to_node(entry);
+		xa_dump_node(node);
+		for (i = 0; i < XA_CHUNK_SIZE; i++)
+			xa_dump_entry(node->slots[i],
+				      index + (i << node->shift), node->shift);
+	} else if (xa_is_value(entry))
+		pr_cont("value %ld (0x%lx)\n", xa_to_value(entry),
+							xa_to_value(entry));
+	else if (!xa_is_internal(entry))
+		pr_cont("%px\n", entry);
+	else if (xa_is_retry(entry))
+		pr_cont("retry (%ld)\n", xa_to_internal(entry));
+	else if (xa_is_sibling(entry))
+		pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry));
+	else
+		pr_cont("UNKNOWN ENTRY (%px)\n", entry);
+}
+
+void xa_dump(const struct xarray *xa)
+{
+	void *entry = xa->xa_head;
+	unsigned int shift = 0;
+
+	pr_info("xarray: %px head %px flags %x tags %d %d %d\n", xa, entry,
+			xa->xa_flags, radix_tree_tagged(xa, 0),
+			radix_tree_tagged(xa, 1), radix_tree_tagged(xa, 2));
+	if (xa_is_node(entry))
+		shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT;
+	xa_dump_entry(entry, 0, shift);
+}
+#endif
diff --git a/tools/include/linux/kernel.h b/tools/include/linux/kernel.h
index 0ad884452c5c..6935ef94e77a 100644
--- a/tools/include/linux/kernel.h
+++ b/tools/include/linux/kernel.h
@@ -70,6 +70,7 @@
 #define BUG_ON(cond) assert(!(cond))
 #endif
 #endif
+#define BUG()	BUG_ON(1)
 
 #if __BYTE_ORDER == __BIG_ENDIAN
 #define cpu_to_le16 bswap_16
diff --git a/tools/testing/radix-tree/.gitignore b/tools/testing/radix-tree/.gitignore
index d4706c0ffceb..3834899b6693 100644
--- a/tools/testing/radix-tree/.gitignore
+++ b/tools/testing/radix-tree/.gitignore
@@ -4,3 +4,4 @@ idr-test
 main
 multiorder
 radix-tree.c
+xarray
diff --git a/tools/testing/radix-tree/Makefile b/tools/testing/radix-tree/Makefile
index 0f9aa462829d..5d224c15f0fd 100644
--- a/tools/testing/radix-tree/Makefile
+++ b/tools/testing/radix-tree/Makefile
@@ -4,7 +4,7 @@ CFLAGS += -I. -I../../include -g -Og -Wall -D_LGPL_SOURCE -fsanitize=address \
 	  -fsanitize=undefined
 LDFLAGS += -fsanitize=address -fsanitize=undefined
 LDLIBS+= -lpthread -lurcu
-TARGETS = main idr-test multiorder
+TARGETS = main idr-test multiorder xarray
 CORE_OFILES := xarray.o radix-tree.o idr.o linux.o test.o find_bit.o
 OFILES = main.o $(CORE_OFILES) regression1.o regression2.o regression3.o \
 	 tag_check.o multiorder.o idr-test.o iteration_check.o benchmark.o
@@ -24,6 +24,8 @@ main:	$(OFILES)
 
 idr-test: idr-test.o $(CORE_OFILES)
 
+xarray: $(CORE_OFILES)
+
 multiorder: multiorder.o $(CORE_OFILES)
 
 clean:
@@ -44,7 +46,7 @@ radix-tree.c: ../../../lib/radix-tree.c
 idr.c: ../../../lib/idr.c
 	sed -e 's/^static //' -e 's/__always_inline //' -e 's/inline //' < $< > $@
 
-xarray.o: ../../../lib/xarray.c
+xarray.o: ../../../lib/xarray.c ../../../lib/test_xarray.c
 
 generated/map-shift.h:
 	@if ! grep -qws $(SHIFT) generated/map-shift.h; then		\
diff --git a/tools/testing/radix-tree/linux/kernel.h b/tools/testing/radix-tree/linux/kernel.h
index 426f32f28547..5d06ac75a14d 100644
--- a/tools/testing/radix-tree/linux/kernel.h
+++ b/tools/testing/radix-tree/linux/kernel.h
@@ -14,6 +14,7 @@
 #include "../../../include/linux/kconfig.h"
 
 #define printk printf
+#define pr_info printk
 #define pr_debug printk
 #define pr_cont printk
 
diff --git a/tools/testing/radix-tree/linux/rcupdate.h b/tools/testing/radix-tree/linux/rcupdate.h
index 73ed33658203..fd280b070fdb 100644
--- a/tools/testing/radix-tree/linux/rcupdate.h
+++ b/tools/testing/radix-tree/linux/rcupdate.h
@@ -6,5 +6,7 @@
 
 #define rcu_dereference_raw(p) rcu_dereference(p)
 #define rcu_dereference_protected(p, cond) rcu_dereference(p)
+#define rcu_dereference_check(p, cond) rcu_dereference(p)
+#define RCU_INIT_POINTER(p, v)	(p) = (v)
 
 #endif
diff --git a/tools/testing/radix-tree/main.c b/tools/testing/radix-tree/main.c
index 584a8732f5ce..a45741102964 100644
--- a/tools/testing/radix-tree/main.c
+++ b/tools/testing/radix-tree/main.c
@@ -365,6 +365,7 @@ int main(int argc, char **argv)
 	rcu_register_thread();
 	radix_tree_init();
 
+	xarray_tests();
 	regression1_test();
 	regression2_test();
 	regression3_test();
diff --git a/tools/testing/radix-tree/test.h b/tools/testing/radix-tree/test.h
index 31f1d9b6f506..2d47e32f9081 100644
--- a/tools/testing/radix-tree/test.h
+++ b/tools/testing/radix-tree/test.h
@@ -34,6 +34,7 @@ int tag_tagged_items(struct radix_tree_root *, pthread_mutex_t *,
 			unsigned iftag, unsigned thentag);
 unsigned long find_item(struct radix_tree_root *, void *item);
 
+void xarray_tests(void);
 void tag_check(void);
 void multiorder_checks(void);
 void iteration_test(unsigned order, unsigned duration);
diff --git a/tools/testing/radix-tree/xarray.c b/tools/testing/radix-tree/xarray.c
index 9bbd667172a7..844baa1a337d 100644
--- a/tools/testing/radix-tree/xarray.c
+++ b/tools/testing/radix-tree/xarray.c
@@ -4,4 +4,30 @@
  * Copyright (c) 2018 Matthew Wilcox <willy@infradead.org>
  */
 
+#include "test.h"
+
+#define module_init(x)
+#define module_exit(x)
+#define dump_stack()	assert(0)
+
+#define XA_DEBUG
 #include "../../../lib/xarray.c"
+#undef XA_DEBUG
+#include "../../../lib/test_xarray.c"
+
+void xarray_tests(void)
+{
+	xarray_checks();
+	xarray_exit();
+}
+
+int __weak main(void)
+{
+	radix_tree_init();
+	xarray_tests();
+	radix_tree_cpu_dead(1);
+	rcu_barrier();
+	if (nr_allocated)
+		printf("nr_allocated = %d\n", nr_allocated);
+	return 0;
+}
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 10/74] xarray: Add XArray tags
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (8 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 09/74] xarray: Add XArray load operation Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 11/74] xarray: Add XArray unconditional store operations Matthew Wilcox
                   ` (64 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

XArray tags are slightly more strongly typed than the radix tree tags,
but occupy the same bits.  This commit adds the basic get/set/clear
operations.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/xarray.h                        |  63 +++++
 lib/test_xarray.c                             |  34 +++
 lib/xarray.c                                  | 227 +++++++++++++++++-
 tools/include/asm-generic/bitops.h            |   1 +
 tools/include/asm-generic/bitops/atomic.h     |   9 -
 tools/include/asm-generic/bitops/non-atomic.h | 109 +++++++++
 tools/include/linux/spinlock.h                |  10 +-
 7 files changed, 440 insertions(+), 13 deletions(-)
 create mode 100644 tools/include/asm-generic/bitops/non-atomic.h

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 074ba6db110f..1a05055710a7 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -11,6 +11,7 @@
 
 #include <linux/bug.h>
 #include <linux/compiler.h>
+#include <linux/gfp.h>
 #include <linux/kconfig.h>
 #include <linux/kernel.h>
 #include <linux/rcupdate.h>
@@ -149,6 +150,20 @@ static inline int xa_err(void *entry)
 	return 0;
 }
 
+typedef unsigned __bitwise xa_tag_t;
+#define XA_TAG_0		((__force xa_tag_t)0U)
+#define XA_TAG_1		((__force xa_tag_t)1U)
+#define XA_TAG_2		((__force xa_tag_t)2U)
+#define XA_PRESENT		((__force xa_tag_t)8U)
+#define XA_TAG_MAX		XA_TAG_2
+
+/*
+ * Values for xa_flags.  The radix tree stores its GFP flags in the xa_flags,
+ * and we remain compatible with that.
+ */
+#define XA_FLAGS_TAG(tag)	((__force gfp_t)((1U << __GFP_BITS_SHIFT) << \
+						(__force unsigned)(tag)))
+
 /**
  * struct xarray - The anchor of the XArray.
  * @xa_lock: Lock that protects the contents of the XArray.
@@ -195,6 +210,9 @@ struct xarray {
 
 void xa_init_flags(struct xarray *, gfp_t flags);
 void *xa_load(struct xarray *, unsigned long index);
+bool xa_get_tag(struct xarray *, unsigned long index, xa_tag_t);
+void xa_set_tag(struct xarray *, unsigned long index, xa_tag_t);
+void xa_clear_tag(struct xarray *, unsigned long index, xa_tag_t);
 
 /**
  * xa_init() - Initialise an empty XArray.
@@ -221,6 +239,19 @@ static inline bool xa_empty(const struct xarray *xa)
 	return xa->xa_head == NULL;
 }
 
+/**
+ * xa_tagged() - Inquire whether any entry in this array has a tag set
+ * @xa: Array
+ * @tag: Tag value
+ *
+ * Context: Any context.
+ * Return: %true if any entry has this tag set.
+ */
+static inline bool xa_tagged(const struct xarray *xa, xa_tag_t tag)
+{
+	return xa->xa_flags & XA_FLAGS_TAG(tag);
+}
+
 #define xa_trylock(xa)		spin_trylock(&(xa)->xa_lock)
 #define xa_lock(xa)		spin_lock(&(xa)->xa_lock)
 #define xa_unlock(xa)		spin_unlock(&(xa)->xa_lock)
@@ -233,6 +264,12 @@ static inline bool xa_empty(const struct xarray *xa)
 #define xa_unlock_irqrestore(xa, flags) \
 				spin_unlock_irqrestore(&(xa)->xa_lock, flags)
 
+/*
+ * Versions of the normal API which require the caller to hold the xa_lock.
+ */
+void __xa_set_tag(struct xarray *, unsigned long index, xa_tag_t);
+void __xa_clear_tag(struct xarray *, unsigned long index, xa_tag_t);
+
 /* Everything below here is the Advanced API.  Proceed with caution. */
 
 /*
@@ -328,6 +365,22 @@ static inline void *xa_entry_locked(const struct xarray *xa,
 						lockdep_is_held(&xa->xa_lock));
 }
 
+/* Private */
+static inline struct xa_node *xa_parent(const struct xarray *xa,
+					const struct xa_node *node)
+{
+	return rcu_dereference_check(node->parent,
+						lockdep_is_held(&xa->xa_lock));
+}
+
+/* Private */
+static inline struct xa_node *xa_parent_locked(const struct xarray *xa,
+					const struct xa_node *node)
+{
+	return rcu_dereference_protected(node->parent,
+						lockdep_is_held(&xa->xa_lock));
+}
+
 /* Private */
 static inline struct xa_node *xa_to_node(const void *entry)
 {
@@ -529,6 +582,12 @@ static inline bool xas_valid(const struct xa_state *xas)
 	return !xas_invalid(xas);
 }
 
+/* True if the pointer is something other than a node */
+static inline bool xas_not_node(struct xa_node *node)
+{
+	return ((unsigned long)node & 3) || !node;
+}
+
 /**
  * xas_reset() - Reset an XArray operation state.
  * @xas: XArray operation state.
@@ -566,6 +625,10 @@ static inline bool xas_retry(struct xa_state *xas, const void *entry)
 
 void *xas_load(struct xa_state *);
 
+bool xas_get_tag(const struct xa_state *, xa_tag_t);
+void xas_set_tag(const struct xa_state *, xa_tag_t);
+void xas_clear_tag(const struct xa_state *, xa_tag_t);
+
 /**
  * xas_reload() - Refetch an entry from the xarray.
  * @xas: XArray operation state.
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index e38dd42a3f7c..5b6b6b5561b1 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -66,11 +66,45 @@ static void check_xa_load(struct xarray *xa)
 	XA_BUG_ON(xa, !xa_empty(xa));
 }
 
+static void check_xa_tag_1(struct xarray *xa, unsigned long index)
+{
+	/* NULL elements have no tags set */
+	XA_BUG_ON(xa, xa_get_tag(xa, index, XA_TAG_0));
+	xa_set_tag(xa, index, XA_TAG_0);
+	XA_BUG_ON(xa, xa_get_tag(xa, index, XA_TAG_0));
+
+	/* Storing a pointer will not make a tag appear */
+	XA_BUG_ON(xa, xa_store_value(xa, index, GFP_KERNEL) != NULL);
+	XA_BUG_ON(xa, xa_get_tag(xa, index, XA_TAG_0));
+	xa_set_tag(xa, index, XA_TAG_0);
+	XA_BUG_ON(xa, !xa_get_tag(xa, index, XA_TAG_0));
+
+	/* Setting one tag will not set another tag */
+	XA_BUG_ON(xa, xa_get_tag(xa, index + 1, XA_TAG_0));
+	XA_BUG_ON(xa, xa_get_tag(xa, index, XA_TAG_1));
+
+	/* Storing NULL clears tags, and they can't be set again */
+	xa_erase_value(xa, index);
+	XA_BUG_ON(xa, !xa_empty(xa));
+	XA_BUG_ON(xa, xa_get_tag(xa, index, XA_TAG_0));
+	xa_set_tag(xa, index, XA_TAG_0);
+	XA_BUG_ON(xa, xa_get_tag(xa, index, XA_TAG_0));
+}
+
+static void check_xa_tag(struct xarray *xa)
+{
+	check_xa_tag_1(xa, 0);
+	check_xa_tag_1(xa, 4);
+	check_xa_tag_1(xa, 64);
+	check_xa_tag_1(xa, 4096);
+}
+
 static int xarray_checks(void)
 {
 	RADIX_TREE(array, GFP_KERNEL);
 
 	check_xa_load(&array);
+	check_xa_tag(&array);
 
 	printk("XArray: %u of %u tests passed\n", tests_passed, tests_run);
 	return (tests_run != tests_passed) ? 0 : -EINVAL;
diff --git a/lib/xarray.c b/lib/xarray.c
index 4d291965e590..aaa800c16e2b 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -5,6 +5,7 @@
  * Author: Matthew Wilcox <willy@infradead.org>
  */
 
+#include <linux/bitmap.h>
 #include <linux/export.h>
 #include <linux/xarray.h>
 
@@ -24,6 +25,43 @@
  * @entry refers to something stored in a slot in the xarray
  */
 
+static inline void xa_tag_set(struct xarray *xa, xa_tag_t tag)
+{
+	if (!(xa->xa_flags & XA_FLAGS_TAG(tag)))
+		xa->xa_flags |= XA_FLAGS_TAG(tag);
+}
+
+static inline void xa_tag_clear(struct xarray *xa, xa_tag_t tag)
+{
+	if (xa->xa_flags & XA_FLAGS_TAG(tag))
+		xa->xa_flags &= ~(XA_FLAGS_TAG(tag));
+}
+
+static inline bool node_get_tag(const struct xa_node *node, unsigned int offset,
+				xa_tag_t tag)
+{
+	return test_bit(offset, node->tags[(__force unsigned)tag]);
+}
+
+/* returns true if the bit was set */
+static inline bool node_set_tag(struct xa_node *node, unsigned int offset,
+				xa_tag_t tag)
+{
+	return __test_and_set_bit(offset, node->tags[(__force unsigned)tag]);
+}
+
+/* returns true if the bit was set */
+static inline bool node_clear_tag(struct xa_node *node, unsigned int offset,
+				xa_tag_t tag)
+{
+	return __test_and_clear_bit(offset, node->tags[(__force unsigned)tag]);
+}
+
+static inline bool node_any_tag(struct xa_node *node, xa_tag_t tag)
+{
+	return !bitmap_empty(node->tags[(__force unsigned)tag], XA_CHUNK_SIZE);
+}
+
 /* extracts the offset within this node from the index */
 static unsigned int get_offset(unsigned long index, struct xa_node *node)
 {
@@ -119,6 +157,85 @@ void *xas_load(struct xa_state *xas)
 }
 EXPORT_SYMBOL_GPL(xas_load);
 
+/**
+ * xas_get_tag() - Returns the state of this tag.
+ * @xas: XArray operation state.
+ * @tag: Tag number.
+ *
+ * Return: true if the tag is set, false if the tag is clear or @xas
+ * is in an error state.
+ */
+bool xas_get_tag(const struct xa_state *xas, xa_tag_t tag)
+{
+	if (xas_invalid(xas))
+		return false;
+	if (!xas->xa_node)
+		return xa_tagged(xas->xa, tag);
+	return node_get_tag(xas->xa_node, xas->xa_offset, tag);
+}
+EXPORT_SYMBOL_GPL(xas_get_tag);
+
+/**
+ * xas_set_tag() - Sets the tag on this entry and its parents.
+ * @xas: XArray operation state.
+ * @tag: Tag number.
+ *
+ * Sets the specified tag on this entry, and walks up the tree setting it
+ * on all the ancestor entries.  Does nothing if @xas has not been walked to
+ * an entry, or is in an error state.
+ */
+void xas_set_tag(const struct xa_state *xas, xa_tag_t tag)
+{
+	struct xa_node *node = xas->xa_node;
+	unsigned int offset = xas->xa_offset;
+
+	if (xas_invalid(xas))
+		return;
+
+	while (node) {
+		if (node_set_tag(node, offset, tag))
+			return;
+		offset = node->offset;
+		node = xa_parent_locked(xas->xa, node);
+	}
+
+	if (!xa_tagged(xas->xa, tag))
+		xa_tag_set(xas->xa, tag);
+}
+EXPORT_SYMBOL_GPL(xas_set_tag);
+
+/**
+ * xas_clear_tag() - Clears the tag on this entry and its parents.
+ * @xas: XArray operation state.
+ * @tag: Tag number.
+ *
+ * Clears the specified tag on this entry, and walks back to the head
+ * attempting to clear it on all the ancestor entries.  Does nothing if
+ * @xas has not been walked to an entry, or is in an error state.
+ */
+void xas_clear_tag(const struct xa_state *xas, xa_tag_t tag)
+{
+	struct xa_node *node = xas->xa_node;
+	unsigned int offset = xas->xa_offset;
+
+	if (xas_invalid(xas))
+		return;
+
+	while (node) {
+		if (!node_clear_tag(node, offset, tag))
+			return;
+		if (node_any_tag(node, tag))
+			return;
+
+		offset = node->offset;
+		node = xa_parent_locked(xas->xa, node);
+	}
+
+	if (xa_tagged(xas->xa, tag))
+		xa_tag_clear(xas->xa, tag);
+}
+EXPORT_SYMBOL_GPL(xas_clear_tag);
+
 /**
  * xa_init_flags() - Initialise an empty XArray with flags.
  * @xa: XArray.
@@ -161,6 +278,112 @@ void *xa_load(struct xarray *xa, unsigned long index)
 }
 EXPORT_SYMBOL(xa_load);
 
+/**
+ * __xa_set_tag() - Set this tag on this entry while locked.
+ * @xa: XArray.
+ * @index: Index of entry.
+ * @tag: Tag number.
+ *
+ * Attempting to set a tag on a NULL entry does not succeed.
+ *
+ * Context: Any context.  Expects xa_lock to be held on entry.
+ */
+void __xa_set_tag(struct xarray *xa, unsigned long index, xa_tag_t tag)
+{
+	XA_STATE(xas, xa, index);
+	void *entry = xas_load(&xas);
+
+	if (entry)
+		xas_set_tag(&xas, tag);
+}
+EXPORT_SYMBOL_GPL(__xa_set_tag);
+
+/**
+ * __xa_clear_tag() - Clear this tag on this entry while locked.
+ * @xa: XArray.
+ * @index: Index of entry.
+ * @tag: Tag number.
+ *
+ * Context: Any context.  Expects xa_lock to be held on entry.
+ */
+void __xa_clear_tag(struct xarray *xa, unsigned long index, xa_tag_t tag)
+{
+	XA_STATE(xas, xa, index);
+	void *entry = xas_load(&xas);
+
+	if (entry)
+		xas_clear_tag(&xas, tag);
+}
+EXPORT_SYMBOL_GPL(__xa_clear_tag);
+
+/**
+ * xa_get_tag() - Inquire whether this tag is set on this entry.
+ * @xa: XArray.
+ * @index: Index of entry.
+ * @tag: Tag number.
+ *
+ * This function uses the RCU read lock, so the result may be out of date
+ * by the time it returns.  If you need the result to be stable, use a lock.
+ *
+ * Context: Any context.  Takes and releases the RCU lock.
+ * Return: True if the entry at @index has this tag set, false if it doesn't.
+ */
+bool xa_get_tag(struct xarray *xa, unsigned long index, xa_tag_t tag)
+{
+	XA_STATE(xas, xa, index);
+	void *entry;
+
+	rcu_read_lock();
+	entry = xas_start(&xas);
+	while (xas_get_tag(&xas, tag)) {
+		if (!xa_is_node(entry))
+			goto found;
+		entry = xas_descend(&xas, xa_to_node(entry));
+	}
+	rcu_read_unlock();
+	return false;
+ found:
+	rcu_read_unlock();
+	return true;
+}
+EXPORT_SYMBOL(xa_get_tag);
+
+/**
+ * xa_set_tag() - Set this tag on this entry.
+ * @xa: XArray.
+ * @index: Index of entry.
+ * @tag: Tag number.
+ *
+ * Attempting to set a tag on a NULL entry does not succeed.
+ *
+ * Context: Process context.  Takes and releases the xa_lock.
+ */
+void xa_set_tag(struct xarray *xa, unsigned long index, xa_tag_t tag)
+{
+	xa_lock(xa);
+	__xa_set_tag(xa, index, tag);
+	xa_unlock(xa);
+}
+EXPORT_SYMBOL(xa_set_tag);
+
+/**
+ * xa_clear_tag() - Clear this tag on this entry.
+ * @xa: XArray.
+ * @index: Index of entry.
+ * @tag: Tag number.
+ *
+ * Clearing a tag always succeeds.
+ *
+ * Context: Process context.  Takes and releases the xa_lock.
+ */
+void xa_clear_tag(struct xarray *xa, unsigned long index, xa_tag_t tag)
+{
+	xa_lock(xa);
+	__xa_clear_tag(xa, index, tag);
+	xa_unlock(xa);
+}
+EXPORT_SYMBOL(xa_clear_tag);
+
 #ifdef XA_DEBUG
 void xa_dump_node(const struct xa_node *node)
 {
@@ -227,8 +450,8 @@ void xa_dump(const struct xarray *xa)
 	unsigned int shift = 0;
 
 	pr_info("xarray: %px head %px flags %x tags %d %d %d\n", xa, entry,
-			xa->xa_flags, radix_tree_tagged(xa, 0),
-			radix_tree_tagged(xa, 1), radix_tree_tagged(xa, 2));
+			xa->xa_flags, xa_tagged(xa, XA_TAG_0),
+			xa_tagged(xa, XA_TAG_1), xa_tagged(xa, XA_TAG_2));
 	if (xa_is_node(entry))
 		shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT;
 	xa_dump_entry(entry, 0, shift);
diff --git a/tools/include/asm-generic/bitops.h b/tools/include/asm-generic/bitops.h
index 9bce3b56b5e7..5d2ab38965cc 100644
--- a/tools/include/asm-generic/bitops.h
+++ b/tools/include/asm-generic/bitops.h
@@ -27,5 +27,6 @@
 #include <asm-generic/bitops/hweight.h>
 
 #include <asm-generic/bitops/atomic.h>
+#include <asm-generic/bitops/non-atomic.h>
 
 #endif /* __TOOLS_ASM_GENERIC_BITOPS_H */
diff --git a/tools/include/asm-generic/bitops/atomic.h b/tools/include/asm-generic/bitops/atomic.h
index 21c41ccd1266..2f6ea28764a7 100644
--- a/tools/include/asm-generic/bitops/atomic.h
+++ b/tools/include/asm-generic/bitops/atomic.h
@@ -15,13 +15,4 @@ static inline void clear_bit(int nr, unsigned long *addr)
 	addr[nr / __BITS_PER_LONG] &= ~(1UL << (nr % __BITS_PER_LONG));
 }
 
-static __always_inline int test_bit(unsigned int nr, const unsigned long *addr)
-{
-	return ((1UL << (nr % __BITS_PER_LONG)) &
-		(((unsigned long *)addr)[nr / __BITS_PER_LONG])) != 0;
-}
-
-#define __set_bit(nr, addr)	set_bit(nr, addr)
-#define __clear_bit(nr, addr)	clear_bit(nr, addr)
-
 #endif /* _TOOLS_LINUX_ASM_GENERIC_BITOPS_ATOMIC_H_ */
diff --git a/tools/include/asm-generic/bitops/non-atomic.h b/tools/include/asm-generic/bitops/non-atomic.h
new file mode 100644
index 000000000000..7e10c4b50c5d
--- /dev/null
+++ b/tools/include/asm-generic/bitops/non-atomic.h
@@ -0,0 +1,109 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_GENERIC_BITOPS_NON_ATOMIC_H_
+#define _ASM_GENERIC_BITOPS_NON_ATOMIC_H_
+
+#include <asm/types.h>
+
+/**
+ * __set_bit - Set a bit in memory
+ * @nr: the bit to set
+ * @addr: the address to start counting from
+ *
+ * Unlike set_bit(), this function is non-atomic and may be reordered.
+ * If it's called on the same region of memory simultaneously, the effect
+ * may be that only one operation succeeds.
+ */
+static inline void __set_bit(int nr, volatile unsigned long *addr)
+{
+	unsigned long mask = BIT_MASK(nr);
+	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+
+	*p  |= mask;
+}
+
+static inline void __clear_bit(int nr, volatile unsigned long *addr)
+{
+	unsigned long mask = BIT_MASK(nr);
+	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+
+	*p &= ~mask;
+}
+
+/**
+ * __change_bit - Toggle a bit in memory
+ * @nr: the bit to change
+ * @addr: the address to start counting from
+ *
+ * Unlike change_bit(), this function is non-atomic and may be reordered.
+ * If it's called on the same region of memory simultaneously, the effect
+ * may be that only one operation succeeds.
+ */
+static inline void __change_bit(int nr, volatile unsigned long *addr)
+{
+	unsigned long mask = BIT_MASK(nr);
+	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+
+	*p ^= mask;
+}
+
+/**
+ * __test_and_set_bit - Set a bit and return its old value
+ * @nr: Bit to set
+ * @addr: Address to count from
+ *
+ * This operation is non-atomic and can be reordered.
+ * If two examples of this operation race, one can appear to succeed
+ * but actually fail.  You must protect multiple accesses with a lock.
+ */
+static inline int __test_and_set_bit(int nr, volatile unsigned long *addr)
+{
+	unsigned long mask = BIT_MASK(nr);
+	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+	unsigned long old = *p;
+
+	*p = old | mask;
+	return (old & mask) != 0;
+}
+
+/**
+ * __test_and_clear_bit - Clear a bit and return its old value
+ * @nr: Bit to clear
+ * @addr: Address to count from
+ *
+ * This operation is non-atomic and can be reordered.
+ * If two examples of this operation race, one can appear to succeed
+ * but actually fail.  You must protect multiple accesses with a lock.
+ */
+static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr)
+{
+	unsigned long mask = BIT_MASK(nr);
+	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+	unsigned long old = *p;
+
+	*p = old & ~mask;
+	return (old & mask) != 0;
+}
+
+/* WARNING: non atomic and it can be reordered! */
+static inline int __test_and_change_bit(int nr,
+					    volatile unsigned long *addr)
+{
+	unsigned long mask = BIT_MASK(nr);
+	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+	unsigned long old = *p;
+
+	*p = old ^ mask;
+	return (old & mask) != 0;
+}
+
+/**
+ * test_bit - Determine whether a bit is set
+ * @nr: bit number to test
+ * @addr: Address to start counting from
+ */
+static inline int test_bit(int nr, const volatile unsigned long *addr)
+{
+	return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
+}
+
+#endif /* _ASM_GENERIC_BITOPS_NON_ATOMIC_H_ */
diff --git a/tools/include/linux/spinlock.h b/tools/include/linux/spinlock.h
index 1738c0391da4..622266b197d0 100644
--- a/tools/include/linux/spinlock.h
+++ b/tools/include/linux/spinlock.h
@@ -8,8 +8,14 @@
 #define spinlock_t		pthread_mutex_t
 #define DEFINE_SPINLOCK(x)	pthread_mutex_t x = PTHREAD_MUTEX_INITIALIZER
 #define __SPIN_LOCK_UNLOCKED(x)	(pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER
-#define spin_lock_init(x)      pthread_mutex_init(x, NULL)
-
+#define spin_lock_init(x)	pthread_mutex_init(x, NULL)
+
+#define spin_lock(x)			pthread_mutex_lock(x)
+#define spin_unlock(x)			pthread_mutex_unlock(x)
+#define spin_lock_bh(x)			pthread_mutex_lock(x)
+#define spin_unlock_bh(x)		pthread_mutex_unlock(x)
+#define spin_lock_irq(x)		pthread_mutex_lock(x)
+#define spin_unlock_irq(x)		pthread_mutex_unlock(x)
 #define spin_lock_irqsave(x, f)		(void)f, pthread_mutex_lock(x)
 #define spin_unlock_irqrestore(x, f)	(void)f, pthread_mutex_unlock(x)
 
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 11/74] xarray: Add XArray unconditional store operations
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (9 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 10/74] xarray: Add XArray tags Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 12/74] xarray: Add XArray conditional " Matthew Wilcox
                   ` (63 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

xa_store() differs from radix_tree_insert() in that it will overwrite an
existing element in the array rather than returning an error.  This is
the behaviour which most users want, and those that want more complex
behaviour generally want to use the xas family of routines anyway.

For memory allocation, xa_store() will first attempt to request memory
from the slab allocator; if memory is not immediately available, it will
drop the xa_lock and allocate memory, keeping a pointer in the xa_state.
It does not use the per-CPU cache, although those will continue to exist
until all radix tree users are converted to the xarray.

This patch also includes xa_erase() and __xa_erase() for a streamlined
way to store NULL.  Since there is no need to allocate memory in order
to store a NULL in the XArray, we do not need to trouble the user with
deciding what memory allocation flags to use.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/xarray.h                   |  96 ++++
 lib/radix-tree.c                         |   4 +-
 lib/test_xarray.c                        | 152 ++++-
 lib/xarray.c                             | 684 +++++++++++++++++++++++
 tools/include/linux/bitmap.h             |   1 +
 tools/include/linux/spinlock.h           |   2 +
 tools/testing/radix-tree/Makefile        |   2 +-
 tools/testing/radix-tree/bitmap.c        |  23 +
 tools/testing/radix-tree/linux/kernel.h  |   4 +
 tools/testing/radix-tree/linux/lockdep.h |  11 +
 10 files changed, 972 insertions(+), 7 deletions(-)
 create mode 100644 tools/testing/radix-tree/bitmap.c
 create mode 100644 tools/testing/radix-tree/linux/lockdep.h

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 1a05055710a7..13e5c4084dcd 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -157,10 +157,17 @@ typedef unsigned __bitwise xa_tag_t;
 #define XA_PRESENT		((__force xa_tag_t)8U)
 #define XA_TAG_MAX		XA_TAG_2
 
+enum xa_lock_type {
+	XA_LOCK_IRQ = 1,
+	XA_LOCK_BH = 2,
+};
+
 /*
  * Values for xa_flags.  The radix tree stores its GFP flags in the xa_flags,
  * and we remain compatible with that.
  */
+#define XA_FLAGS_LOCK_IRQ	((__force gfp_t)XA_LOCK_IRQ)
+#define XA_FLAGS_LOCK_BH	((__force gfp_t)XA_LOCK_BH)
 #define XA_FLAGS_TAG(tag)	((__force gfp_t)((1U << __GFP_BITS_SHIFT) << \
 						(__force unsigned)(tag)))
 
@@ -210,6 +217,7 @@ struct xarray {
 
 void xa_init_flags(struct xarray *, gfp_t flags);
 void *xa_load(struct xarray *, unsigned long index);
+void *xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
 bool xa_get_tag(struct xarray *, unsigned long index, xa_tag_t);
 void xa_set_tag(struct xarray *, unsigned long index, xa_tag_t);
 void xa_clear_tag(struct xarray *, unsigned long index, xa_tag_t);
@@ -252,6 +260,23 @@ static inline bool xa_tagged(const struct xarray *xa, xa_tag_t tag)
 	return xa->xa_flags & XA_FLAGS_TAG(tag);
 }
 
+/**
+ * xa_erase() - Erase this entry from the XArray.
+ * @xa: XArray.
+ * @index: Index of entry.
+ *
+ * This function is the equivalent of calling xa_store() with %NULL as
+ * the third argument.  The XArray does not need to allocate memory, so
+ * the user does not need to provide GFP flags.
+ *
+ * Context: Process context.  Takes and releases the xa_lock.
+ * Return: The entry which used to be at this index.
+ */
+static inline void *xa_erase(struct xarray *xa, unsigned long index)
+{
+	return xa_store(xa, index, NULL, 0);
+}
+
 #define xa_trylock(xa)		spin_trylock(&(xa)->xa_lock)
 #define xa_lock(xa)		spin_lock(&(xa)->xa_lock)
 #define xa_unlock(xa)		spin_unlock(&(xa)->xa_lock)
@@ -266,7 +291,11 @@ static inline bool xa_tagged(const struct xarray *xa, xa_tag_t tag)
 
 /*
  * Versions of the normal API which require the caller to hold the xa_lock.
+ * If the GFP flags allow it, will drop the lock in order to allocate
+ * memory, then reacquire it afterwards.
  */
+void *__xa_erase(struct xarray *, unsigned long index);
+void *__xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
 void __xa_set_tag(struct xarray *, unsigned long index, xa_tag_t);
 void __xa_clear_tag(struct xarray *, unsigned long index, xa_tag_t);
 
@@ -381,6 +410,12 @@ static inline struct xa_node *xa_parent_locked(const struct xarray *xa,
 						lockdep_is_held(&xa->xa_lock));
 }
 
+/* Private */
+static inline void *xa_mk_node(const struct xa_node *node)
+{
+	return (void *)((unsigned long)node | 2);
+}
+
 /* Private */
 static inline struct xa_node *xa_to_node(const void *entry)
 {
@@ -588,6 +623,12 @@ static inline bool xas_not_node(struct xa_node *node)
 	return ((unsigned long)node & 3) || !node;
 }
 
+/* True if the node represents head-of-tree, RESTART or BOUNDS */
+static inline bool xas_top(struct xa_node *node)
+{
+	return node <= XAS_RESTART;
+}
+
 /**
  * xas_reset() - Reset an XArray operation state.
  * @xas: XArray operation state.
@@ -624,10 +665,14 @@ static inline bool xas_retry(struct xa_state *xas, const void *entry)
 }
 
 void *xas_load(struct xa_state *);
+void *xas_store(struct xa_state *, void *entry);
 
 bool xas_get_tag(const struct xa_state *, xa_tag_t);
 void xas_set_tag(const struct xa_state *, xa_tag_t);
 void xas_clear_tag(const struct xa_state *, xa_tag_t);
+void xas_init_tags(const struct xa_state *);
+
+bool xas_nomem(struct xa_state *, gfp_t);
 
 /**
  * xas_reload() - Refetch an entry from the xarray.
@@ -652,4 +697,55 @@ static inline void *xas_reload(struct xa_state *xas)
 	return xa_head(xas->xa);
 }
 
+/**
+ * xas_set() - Set up XArray operation state for a different index.
+ * @xas: XArray operation state.
+ * @index: New index into the XArray.
+ *
+ * Move the operation state to refer to a different index.  This will
+ * have the effect of starting a walk from the top; see xas_next()
+ * to move to an adjacent index.
+ */
+static inline void xas_set(struct xa_state *xas, unsigned long index)
+{
+	xas->xa_index = index;
+	xas->xa_node = XAS_RESTART;
+}
+
+/**
+ * xas_set_order() - Set up XArray operation state for a multislot entry.
+ * @xas: XArray operation state.
+ * @index: Target of the operation.
+ * @order: Entry occupies 2^@order indices.
+ */
+static inline void xas_set_order(struct xa_state *xas, unsigned long index,
+					unsigned int order)
+{
+#ifdef CONFIG_RADIX_TREE_MULTIORDER
+	xas->xa_index = order < BITS_PER_LONG ? (index >> order) << order : 0;
+	xas->xa_shift = order - (order % XA_CHUNK_SHIFT);
+	xas->xa_sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
+	xas->xa_node = XAS_RESTART;
+#else
+	BUG_ON(order > 0);
+	xas_set(xas, index);
+#endif
+}
+
+/**
+ * xas_set_update() - Set up XArray operation state for a callback.
+ * @xas: XArray operation state.
+ * @update: Function to call when updating a node.
+ *
+ * The XArray can notify a caller after it has updated an xa_node.
+ * This is advanced functionality and is only needed by the page cache.
+ */
+static inline void xas_set_update(struct xa_state *xas, xa_update_node_t update)
+{
+	xas->xa_update = update;
+}
+
+/* Internal functions, mostly shared between radix-tree.c, xarray.c and idr.c */
+void xas_destroy(struct xa_state *);
+
 #endif /* _LINUX_XARRAY_H */
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index d20b625d963e..f7785f7cbd5f 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -47,7 +47,7 @@ static unsigned long height_to_maxnodes[RADIX_TREE_MAX_PATH + 1] __read_mostly;
 /*
  * Radix tree node cache.
  */
-static struct kmem_cache *radix_tree_node_cachep;
+struct kmem_cache *radix_tree_node_cachep;
 
 /*
  * The radix tree is variable-height, so an insert operation not only has
@@ -365,7 +365,7 @@ radix_tree_node_alloc(gfp_t gfp_mask, struct radix_tree_node *parent,
 	return ret;
 }
 
-static void radix_tree_node_rcu_free(struct rcu_head *head)
+void radix_tree_node_rcu_free(struct rcu_head *head)
 {
 	struct radix_tree_node *node =
 			container_of(head, struct radix_tree_node, rcu_head);
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index 5b6b6b5561b1..cb6e9910e369 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -29,13 +29,48 @@ void xa_dump(const struct xarray *xa) { }
 
 static void *xa_store_value(struct xarray *xa, unsigned long index, gfp_t gfp)
 {
-	radix_tree_insert(xa, index, xa_mk_value(index));
-	return NULL;
+	return xa_store(xa, index, xa_mk_value(index), gfp);
 }
 
 static void xa_erase_value(struct xarray *xa, unsigned long index)
 {
-	radix_tree_delete(xa, index);
+	XA_BUG_ON(xa, xa_erase(xa, index) != xa_mk_value(index));
+	XA_BUG_ON(xa, xa_load(xa, index) != NULL);
+}
+
+/*
+ * If anyone needs this, please move it to xarray.c.  We have no current
+ * users outside the test suite because all current multislot users want
+ * to use the advanced API.
+ */
+static void *xa_store_order(struct xarray *xa, unsigned long index,
+		unsigned order, void *entry, gfp_t gfp)
+{
+	XA_STATE(xas, xa, 0);
+	void *curr;
+
+	xas_set_order(&xas, index, order);
+	do {
+		curr = xas_store(&xas, entry);
+	} while (xas_nomem(&xas, gfp));
+
+	return curr;
+}
+
+static void check_xa_err(struct xarray *xa)
+{
+	XA_BUG_ON(xa, xa_err(xa_store_value(xa, 0, GFP_NOWAIT)) != 0);
+	XA_BUG_ON(xa, xa_err(xa_erase(xa, 0)) != 0);
+#ifndef __KERNEL__
+	/* The kernel does not fail GFP_NOWAIT allocations */
+	XA_BUG_ON(xa, xa_err(xa_store_value(xa, 1, GFP_NOWAIT)) != -ENOMEM);
+	XA_BUG_ON(xa, xa_err(xa_store_value(xa, 1, GFP_NOWAIT)) != -ENOMEM);
+#endif
+	XA_BUG_ON(xa, xa_err(xa_store_value(xa, 1, GFP_KERNEL)) != 0);
+	XA_BUG_ON(xa, xa_err(xa_store(xa, 1, xa_mk_value(0), GFP_KERNEL)) != 0);
+	XA_BUG_ON(xa, xa_err(xa_erase(xa, 1)) != 0);
+// kills the test-suite :-(
+//	XA_BUG_ON(xa, xa_err(xa_store(xa, 0, xa_mk_internal(0), 0)) != -EINVAL);
 }
 
 static void check_xa_load(struct xarray *xa)
@@ -89,6 +124,25 @@ static void check_xa_tag_1(struct xarray *xa, unsigned long index)
 	XA_BUG_ON(xa, xa_get_tag(xa, index, XA_TAG_0));
 	xa_set_tag(xa, index, XA_TAG_0);
 	XA_BUG_ON(xa, xa_get_tag(xa, index, XA_TAG_0));
+
+	/*
+	 * Storing a multi-index entry over entries with tags gives the
+	 * entire entry the union of the tags
+	 */
+	BUG_ON((index % 4) != 0);
+	XA_BUG_ON(xa, xa_store_value(xa, index + 1, GFP_KERNEL) != NULL);
+	xa_set_tag(xa, index + 1, XA_TAG_0);
+	XA_BUG_ON(xa, xa_store_value(xa, index + 2, GFP_KERNEL) != NULL);
+	xa_set_tag(xa, index + 2, XA_TAG_1);
+	xa_store_order(xa, index, 2, xa_mk_value(index), GFP_KERNEL);
+	XA_BUG_ON(xa, !xa_get_tag(xa, index, XA_TAG_0));
+	XA_BUG_ON(xa, !xa_get_tag(xa, index, XA_TAG_1));
+	XA_BUG_ON(xa, xa_get_tag(xa, index, XA_TAG_2));
+	XA_BUG_ON(xa, !xa_get_tag(xa, index + 1, XA_TAG_0));
+	XA_BUG_ON(xa, !xa_get_tag(xa, index + 1, XA_TAG_1));
+	XA_BUG_ON(xa, xa_get_tag(xa, index + 1, XA_TAG_2));
+	xa_erase_value(xa, index);
+	XA_BUG_ON(xa, !xa_empty(xa));
 }
 
 static void check_xa_tag(struct xarray *xa)
@@ -99,12 +153,102 @@ static void check_xa_tag(struct xarray *xa)
 	check_xa_tag_1(xa, 4096);
 }
 
+static void check_xa_shrink(struct xarray *xa)
+{
+	XA_STATE(xas, xa, 1);
+	struct xa_node *node;
+
+	XA_BUG_ON(xa, !xa_empty(xa));
+	XA_BUG_ON(xa, xa_store_value(xa, 0, GFP_KERNEL) != NULL);
+	XA_BUG_ON(xa, xa_store_value(xa, 1, GFP_KERNEL) != NULL);
+
+	/*
+	 * Check that erasing the entry at 1 shrinks the tree and properly
+	 * marks the node as being deleted.
+	 */
+	XA_BUG_ON(xa, xas_load(&xas) != xa_mk_value(1));
+	node = xas.xa_node;
+	XA_BUG_ON(xa, node->slots[0] != xa_mk_value(0));
+	rcu_read_lock();
+	XA_BUG_ON(xa, xas_store(&xas, NULL) != xa_mk_value(1));
+	XA_BUG_ON(xa, xa_load(xa, 1) != NULL);
+	XA_BUG_ON(xa, xas.xa_node != XAS_BOUNDS);
+	XA_BUG_ON(xa, node->slots[0] != XA_RETRY_ENTRY);
+	XA_BUG_ON(xa, xas_load(&xas) != NULL);
+	rcu_read_unlock();
+	XA_BUG_ON(xa, xa_load(xa, 0) != xa_mk_value(0));
+	xa_erase_value(xa, 0);
+	XA_BUG_ON(xa, !xa_empty(xa));
+}
+
+static void check_multi_store(struct xarray *xa)
+{
+	unsigned long i, j, k;
+
+	/* Loading from any position returns the same value */
+	xa_store_order(xa, 0, 1, xa_mk_value(0), GFP_KERNEL);
+	XA_BUG_ON(xa, xa_load(xa, 0) != xa_mk_value(0));
+	XA_BUG_ON(xa, xa_load(xa, 1) != xa_mk_value(0));
+	XA_BUG_ON(xa, xa_load(xa, 2) != NULL);
+	XA_BUG_ON(xa, xa_to_node(xa_head(xa))->count != 2);
+	XA_BUG_ON(xa, xa_to_node(xa_head(xa))->nr_values != 2);
+
+	/* Storing adjacent to the value does not alter the value */
+	xa_store(xa, 3, xa, GFP_KERNEL);
+	XA_BUG_ON(xa, xa_load(xa, 0) != xa_mk_value(0));
+	XA_BUG_ON(xa, xa_load(xa, 1) != xa_mk_value(0));
+	XA_BUG_ON(xa, xa_load(xa, 2) != NULL);
+	XA_BUG_ON(xa, xa_to_node(xa_head(xa))->count != 3);
+	XA_BUG_ON(xa, xa_to_node(xa_head(xa))->nr_values != 2);
+
+	/* Overwriting multiple indexes works */
+	xa_store_order(xa, 0, 2, xa_mk_value(1), GFP_KERNEL);
+	XA_BUG_ON(xa, xa_load(xa, 0) != xa_mk_value(1));
+	XA_BUG_ON(xa, xa_load(xa, 1) != xa_mk_value(1));
+	XA_BUG_ON(xa, xa_load(xa, 2) != xa_mk_value(1));
+	XA_BUG_ON(xa, xa_load(xa, 3) != xa_mk_value(1));
+	XA_BUG_ON(xa, xa_load(xa, 4) != NULL);
+	XA_BUG_ON(xa, xa_to_node(xa_head(xa))->count != 4);
+	XA_BUG_ON(xa, xa_to_node(xa_head(xa))->nr_values != 4);
+
+	/* We can erase multiple values with a single store */
+	xa_store_order(xa, 0, 64, NULL, GFP_KERNEL);
+	XA_BUG_ON(xa, !xa_empty(xa));
+
+	/* Even when the first slot is empty but the others aren't */
+	xa_store_value(xa, 1, GFP_KERNEL);
+	xa_store_value(xa, 2, GFP_KERNEL);
+	xa_store_order(xa, 0, 2, NULL, GFP_KERNEL);
+	XA_BUG_ON(xa, !xa_empty(xa));
+
+	for (i = 0; i < 60; i++) {
+		for (j = 0; j < 60; j++) {
+			xa_store_order(xa, 0, i, xa_mk_value(i), GFP_KERNEL);
+			xa_store_order(xa, 0, j, xa_mk_value(j), GFP_KERNEL);
+
+			for (k = 0; k < 60; k++) {
+				void *entry = xa_load(xa, (1UL << k) - 1);
+				if ((i < k) && (j < k))
+					XA_BUG_ON(xa, entry != NULL);
+				else
+					XA_BUG_ON(xa, entry != xa_mk_value(j));
+			}
+
+			xa_erase(xa, 0);
+			XA_BUG_ON(xa, !xa_empty(xa));
+		}
+	}
+}
+
 static int xarray_checks(void)
 {
-	RADIX_TREE(array, GFP_KERNEL);
+	DEFINE_XARRAY(array);
 
+	check_xa_err(&array);
 	check_xa_load(&array);
 	check_xa_tag(&array);
+	check_xa_shrink(&array);
+	check_multi_store(&array);
 
 	printk("XArray: %u of %u tests passed\n", tests_passed, tests_run);
 	return (tests_run != tests_passed) ? 0 : -EINVAL;
diff --git a/lib/xarray.c b/lib/xarray.c
index aaa800c16e2b..18043aee8a91 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -7,6 +7,8 @@
 
 #include <linux/bitmap.h>
 #include <linux/export.h>
+#include <linux/list.h>
+#include <linux/slab.h>
 #include <linux/xarray.h>
 
 /*
@@ -25,6 +27,11 @@
  * @entry refers to something stored in a slot in the xarray
  */
 
+static inline unsigned int xa_lock_type(const struct xarray *xa)
+{
+	return (__force unsigned int)xa->xa_flags & 3;
+}
+
 static inline void xa_tag_set(struct xarray *xa, xa_tag_t tag)
 {
 	if (!(xa->xa_flags & XA_FLAGS_TAG(tag)))
@@ -62,6 +69,34 @@ static inline bool node_any_tag(struct xa_node *node, xa_tag_t tag)
 	return !bitmap_empty(node->tags[(__force unsigned)tag], XA_CHUNK_SIZE);
 }
 
+#define tag_inc(tag) do { \
+	tag = (__force xa_tag_t)((__force unsigned)(tag) + 1); \
+} while (0)
+
+/*
+ * xas_squash_tags() - Merge all tags to the first entry
+ * @xas: Array operation state.
+ *
+ * Set a tag on the first entry if any entry has it set.  Clear tags on
+ * all sibling entries.
+ */
+static void xas_squash_tags(const struct xa_state *xas)
+{
+	unsigned int tag = 0;
+	unsigned int limit = xas->xa_offset + xas->xa_sibs;
+
+	if (!xas->xa_sibs)
+		return;
+
+	do {
+		unsigned long *tags = xas->xa_node->tags[tag];
+		if (find_next_bit(tags, limit, xas->xa_offset + 1) == limit)
+			continue;
+		__set_bit(xas->xa_offset, tags);
+		bitmap_clear(tags, xas->xa_offset + 1, xas->xa_sibs);
+	} while (tag++ != (__force unsigned)XA_TAG_MAX);
+}
+
 /* extracts the offset within this node from the index */
 static unsigned int get_offset(unsigned long index, struct xa_node *node)
 {
@@ -157,6 +192,527 @@ void *xas_load(struct xa_state *xas)
 }
 EXPORT_SYMBOL_GPL(xas_load);
 
+/* Move the radix tree node cache here */
+extern struct kmem_cache *radix_tree_node_cachep;
+extern void radix_tree_node_rcu_free(struct rcu_head *head);
+
+#define XA_RCU_FREE	((struct xarray *)1)
+
+static void xa_node_free(struct xa_node *node)
+{
+	XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
+	node->array = XA_RCU_FREE;
+	call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
+}
+
+/*
+ * xas_destroy() - Free any resources allocated during the XArray operation.
+ * @xas: XArray operation state.
+ *
+ * This function is now internal-only (and will be made static once
+ * idr_preload() is removed).
+ */
+void xas_destroy(struct xa_state *xas)
+{
+	struct xa_node *node = xas->xa_alloc;
+
+	if (!node)
+		return;
+	XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
+	kmem_cache_free(radix_tree_node_cachep, node);
+	xas->xa_alloc = NULL;
+}
+
+/**
+ * xas_nomem() - Allocate memory if needed.
+ * @xas: XArray operation state.
+ * @gfp: Memory allocation flags.
+ *
+ * If we need to add new nodes to the XArray, we try to allocate memory
+ * with GFP_NOWAIT while holding the lock, which will usually succeed.
+ * If it fails, @xas is flagged as needing memory to continue.  The caller
+ * should drop the lock and call xas_nomem().  If xas_nomem() succeeds,
+ * the caller should retry the operation.
+ *
+ * Forward progress is guaranteed as one node is allocated here and
+ * stored in the xa_state where it will be found by xas_alloc().  More
+ * nodes will likely be found in the slab allocator, but we do not tie
+ * them up here.
+ *
+ * Return: true if memory was needed, and was successfully allocated.
+ */
+bool xas_nomem(struct xa_state *xas, gfp_t gfp)
+{
+	if (xas->xa_node != XA_ERROR(-ENOMEM)) {
+		xas_destroy(xas);
+		return false;
+	}
+	xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
+	if (!xas->xa_alloc)
+		return false;
+	XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
+	xas->xa_node = XAS_RESTART;
+	return true;
+}
+EXPORT_SYMBOL_GPL(xas_nomem);
+
+/*
+ * __xas_nomem() - Drop locks and allocate memory if needed.
+ * @xas: XArray operation state.
+ * @gfp: Memory allocation flags.
+ *
+ * Internal variant of xas_nomem().
+ *
+ * Return: true if memory was needed, and was successfully allocated.
+ */
+static bool __xas_nomem(struct xa_state *xas, gfp_t gfp)
+	__must_hold(xas->xa->xa_lock)
+{
+	unsigned int lock_type = xa_lock_type(xas->xa);
+
+	if (xas->xa_node != XA_ERROR(-ENOMEM)) {
+		xas_destroy(xas);
+		return false;
+	}
+	if (gfpflags_allow_blocking(gfp)) {
+		if (lock_type == XA_LOCK_IRQ)
+			xas_unlock_irq(xas);
+		else if (lock_type == XA_LOCK_BH)
+			xas_unlock_bh(xas);
+		else
+			xas_unlock(xas);
+		xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
+		if (lock_type == XA_LOCK_IRQ)
+			xas_lock_irq(xas);
+		else if (lock_type == XA_LOCK_BH)
+			xas_lock_bh(xas);
+		else
+			xas_lock(xas);
+	} else {
+		xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
+	}
+	if (!xas->xa_alloc)
+		return false;
+	XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
+	xas->xa_node = XAS_RESTART;
+	return true;
+}
+
+static void xas_update(struct xa_state *xas, struct xa_node *node)
+{
+	if (xas->xa_update)
+		xas->xa_update(node);
+	else
+		XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
+}
+
+static void *xas_alloc(struct xa_state *xas, unsigned int shift)
+{
+	struct xa_node *parent = xas->xa_node;
+	struct xa_node *node = xas->xa_alloc;
+
+	if (xas_invalid(xas))
+		return NULL;
+
+	if (node) {
+		xas->xa_alloc = NULL;
+	} else {
+		node = kmem_cache_alloc(radix_tree_node_cachep,
+					GFP_NOWAIT | __GFP_NOWARN);
+		if (!node) {
+			xas_set_err(xas, -ENOMEM);
+			return NULL;
+		}
+	}
+
+	if (parent) {
+		node->offset = xas->xa_offset;
+		parent->count++;
+		XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE);
+		xas_update(xas, parent);
+	}
+	XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
+	XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
+	node->shift = shift;
+	node->count = 0;
+	node->nr_values = 0;
+	RCU_INIT_POINTER(node->parent, xas->xa_node);
+	node->array = xas->xa;
+
+	return node;
+}
+
+/*
+ * Use this to calculate the maximum index that will need to be created
+ * in order to add the entry described by @xas.  Because we cannot store a
+ * multiple-index entry at index 0, the calculation is a little more complex
+ * than you might expect.
+ */
+static unsigned long xas_max(struct xa_state *xas)
+{
+	unsigned long max = xas->xa_index;
+
+#ifdef CONFIG_RADIX_TREE_MULTIORDER
+	if (xas->xa_shift || xas->xa_sibs) {
+		unsigned long mask;
+		mask = (((xas->xa_sibs + 1UL) << xas->xa_shift) - 1);
+		max |= mask;
+		if (mask == max)
+			max++;
+	}
+#endif
+
+	return max;
+}
+
+/* The maximum index that can be contained in the array without expanding it */
+static unsigned long max_index(void *entry)
+{
+	if (!xa_is_node(entry))
+		return 0;
+	return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1;
+}
+
+static void xas_shrink(struct xa_state *xas)
+{
+	struct xarray *xa = xas->xa;
+	struct xa_node *node = xas->xa_node;
+
+	for (;;) {
+		void *entry;
+
+		XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
+		if (node->count != 1)
+			break;
+		entry = xa_entry_locked(xa, node, 0);
+		if (!entry)
+			break;
+		if (!xa_is_node(entry) && node->shift)
+			break;
+		xas->xa_node = XAS_BOUNDS;
+
+		RCU_INIT_POINTER(xa->xa_head, entry);
+
+		node->count = 0;
+		node->nr_values = 0;
+		if (!xa_is_node(entry))
+			RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY);
+		xas_update(xas, node);
+		xa_node_free(node);
+		if (!xa_is_node(entry))
+			break;
+		node = xa_to_node(entry);
+		node->parent = NULL;
+	}
+}
+
+/*
+ * xas_delete_node() - Attempt to delete an xa_node
+ * @xas: Array operation state.
+ *
+ * Attempts to delete the @xas->xa_node.  This will fail if xa->node has
+ * a non-zero reference count.
+ */
+static void xas_delete_node(struct xa_state *xas)
+{
+	struct xa_node *node = xas->xa_node;
+
+	for (;;) {
+		struct xa_node *parent;
+
+		XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
+		if (node->count)
+			break;
+
+		parent = xa_parent_locked(xas->xa, node);
+		xas->xa_node = parent;
+		xas->xa_offset = node->offset;
+		xa_node_free(node);
+
+		if (!parent) {
+			xas->xa->xa_head = NULL;
+			xas->xa_node = XAS_BOUNDS;
+			return;
+		}
+
+		parent->slots[xas->xa_offset] = NULL;
+		parent->count--;
+		XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE);
+		node = parent;
+		xas_update(xas, node);
+	}
+
+	if (!node->parent)
+		xas_shrink(xas);
+}
+
+/**
+ * xas_free_nodes() - Free this node and all nodes that it references
+ * @xas: Array operation state.
+ * @top: Node to free
+ *
+ * This node has been removed from the tree.  We must now free it and all
+ * of its subnodes.  There may be RCU walkers with references into the tree,
+ * so we must replace all entries with retry markers.
+ */
+static void xas_free_nodes(struct xa_state *xas, struct xa_node *top)
+{
+	unsigned int offset = 0;
+	struct xa_node *node = top;
+
+	for (;;) {
+		void *entry = xa_entry_locked(xas->xa, node, offset);
+
+		if (xa_is_node(entry)) {
+			node = xa_to_node(entry);
+			offset = 0;
+			continue;
+		}
+		if (entry)
+			RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY);
+		offset++;
+		while (offset == XA_CHUNK_SIZE) {
+			struct xa_node *parent;
+
+			parent = xa_parent_locked(xas->xa, node);
+			offset = node->offset + 1;
+			node->count = 0;
+			node->nr_values = 0;
+			xas_update(xas, node);
+			xa_node_free(node);
+			if (node == top)
+				return;
+			node = parent;
+		}
+	}
+}
+
+/*
+ * xas_expand adds nodes to the head of the tree until it has reached
+ * sufficient height to be able to contain @xas->xa_index
+ */
+static int xas_expand(struct xa_state *xas, void *head)
+{
+	struct xarray *xa = xas->xa;
+	struct xa_node *node = NULL;
+	unsigned int shift = 0;
+	unsigned long max = xas_max(xas);
+
+	if (!head) {
+		if (max == 0)
+			return 0;
+		while ((max >> shift) >= XA_CHUNK_SIZE)
+			shift += XA_CHUNK_SHIFT;
+		return shift + XA_CHUNK_SHIFT;
+	} else if (xa_is_node(head)) {
+		node = xa_to_node(head);
+		shift = node->shift + XA_CHUNK_SHIFT;
+	}
+	xas->xa_node = NULL;
+
+	while (max > max_index(head)) {
+		xa_tag_t tag = 0;
+
+		XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
+		node = xas_alloc(xas, shift);
+		if (!node)
+			return -ENOMEM;
+
+		node->count = 1;
+		if (xa_is_value(head))
+			node->nr_values = 1;
+		RCU_INIT_POINTER(node->slots[0], head);
+
+		/* Propagate the aggregated tag info to the new child */
+		for (;;) {
+			if (xa_tagged(xa, tag))
+				node_set_tag(node, 0, tag);
+			if (tag == XA_TAG_MAX)
+				break;
+			tag_inc(tag);
+		}
+
+		/*
+		 * Now that the new node is fully initialised, we can add
+		 * it to the tree
+		 */
+		if (xa_is_node(head)) {
+			xa_to_node(head)->offset = 0;
+			rcu_assign_pointer(xa_to_node(head)->parent, node);
+		}
+		head = xa_mk_node(node);
+		rcu_assign_pointer(xa->xa_head, head);
+		xas_update(xas, node);
+
+		shift += XA_CHUNK_SHIFT;
+	}
+
+	xas->xa_node = node;
+	return shift;
+}
+
+/*
+ * xas_create() - Create a slot to store an entry in.
+ * @xas: XArray operation state.
+ *
+ * Most users will not need to call this function directly, as it is called
+ * by xas_store().  It is useful for doing conditional store operations
+ * (see the xa_cmpxchg() implementation for an example).
+ *
+ * Return: If the slot already existed, returns the contents of this slot.
+ * If the slot was newly created, returns NULL.  If it failed to create the
+ * slot, returns NULL and indicates the error in @xas.
+ */
+static void *xas_create(struct xa_state *xas)
+{
+	struct xarray *xa = xas->xa;
+	void *entry;
+	void __rcu **slot;
+	struct xa_node *node = xas->xa_node;
+	int shift;
+	unsigned int order = xas->xa_shift;
+
+	if (xas_top(node)) {
+		entry = xa_head_locked(xa);
+		xas->xa_node = NULL;
+		shift = xas_expand(xas, entry);
+		if (shift < 0)
+			return NULL;
+		entry = xa_head_locked(xa);
+		slot = &xa->xa_head;
+	} else if (xas_error(xas)) {
+		return NULL;
+	} else if (node) {
+		unsigned int offset = xas->xa_offset;
+
+		shift = node->shift;
+		entry = xa_entry_locked(xa, node, offset);
+		slot = &node->slots[offset];
+	} else {
+		shift = 0;
+		entry = xa_head_locked(xa);
+		slot = &xa->xa_head;
+	}
+
+	while (shift > order) {
+		shift -= XA_CHUNK_SHIFT;
+		if (!entry) {
+			node = xas_alloc(xas, shift);
+			if (!node)
+				break;
+			rcu_assign_pointer(*slot, xa_mk_node(node));
+		} else if (xa_is_node(entry)) {
+			node = xa_to_node(entry);
+		} else {
+			break;
+		}
+		entry = xas_descend(xas, node);
+		slot = &node->slots[xas->xa_offset];
+	}
+
+	return entry;
+}
+
+static void update_node(struct xa_state *xas, struct xa_node *node,
+		int count, int values)
+{
+	if (!node || (!count && !values))
+		return;
+
+	node->count += count;
+	node->nr_values += values;
+	XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
+	XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE);
+	xas_update(xas, node);
+	if (count < 0)
+		xas_delete_node(xas);
+}
+
+/**
+ * xas_store() - Store this entry in the XArray.
+ * @xas: XArray operation state.
+ * @entry: New entry.
+ *
+ * If @xas is operating on a multi-index entry, the entry returned by this
+ * function is essentially meaningless (it may be an internal entry or it
+ * may be %NULL, even if there are non-NULL entries at some of the indices
+ * covered by the range).  This is not a problem for any current users,
+ * and can be changed if needed.
+ *
+ * Return: The old entry at this index.
+ */
+void *xas_store(struct xa_state *xas, void *entry)
+{
+	struct xa_node *node;
+	void __rcu **slot = &xas->xa->xa_head;
+	unsigned int offset, max;
+	int count = 0;
+	int values = 0;
+	void *first, *next;
+	bool value = xa_is_value(entry);
+
+	if (entry)
+		first = xas_create(xas);
+	else
+		first = xas_load(xas);
+
+	if (xas_invalid(xas))
+		return first;
+	node = xas->xa_node;
+	if (node && (xas->xa_shift < node->shift))
+		xas->xa_sibs = 0;
+	if ((first == entry) && !xas->xa_sibs)
+		return first;
+
+	next = first;
+	offset = xas->xa_offset;
+	max = xas->xa_offset + xas->xa_sibs;
+	if (node) {
+		slot = &node->slots[offset];
+		if (xas->xa_sibs)
+			xas_squash_tags(xas);
+	}
+	if (!entry)
+		xas_init_tags(xas);
+
+	for (;;) {
+		/*
+		 * Must clear the tags before setting the entry to NULL,
+		 * otherwise xas_for_each_tagged may find a NULL entry and
+		 * stop early.  rcu_assign_pointer contains a release barrier
+		 * so the tag clearing will appear to happen before the
+		 * entry is set to NULL.
+		 */
+		rcu_assign_pointer(*slot, entry);
+		if (xa_is_node(next))
+			xas_free_nodes(xas, xa_to_node(next));
+		if (!node)
+			break;
+		count += !next - !entry;
+		values += !xa_is_value(first) - !value;
+		if (entry) {
+			if (offset == max)
+				break;
+			if (!xa_is_sibling(entry))
+				entry = xa_mk_sibling(xas->xa_offset);
+		} else {
+			if (offset == XA_CHUNK_MASK)
+				break;
+		}
+		next = xa_entry_locked(xas->xa, node, ++offset);
+		if (!xa_is_sibling(next)) {
+			if (!entry && (offset > max))
+				break;
+			first = next;
+		}
+		slot++;
+	}
+
+	update_node(xas, node, count, values);
+	return first;
+}
+EXPORT_SYMBOL_GPL(xas_store);
+
 /**
  * xas_get_tag() - Returns the state of this tag.
  * @xas: XArray operation state.
@@ -236,6 +792,30 @@ void xas_clear_tag(const struct xa_state *xas, xa_tag_t tag)
 }
 EXPORT_SYMBOL_GPL(xas_clear_tag);
 
+/**
+ * xas_init_tags() - Initialise all tags for the entry
+ * @xas: Array operations state.
+ *
+ * Initialise all tags for the entry specified by @xas.  If we're tracking
+ * free entries with a tag, we need to set it on all entries.  All other
+ * tags are cleared.
+ *
+ * This implementation is not as efficient as it could be; we may walk
+ * up the tree multiple times.
+ */
+void xas_init_tags(const struct xa_state *xas)
+{
+	xa_tag_t tag = 0;
+
+	for (;;) {
+		xas_clear_tag(xas, tag);
+		if (tag == XA_TAG_MAX)
+			break;
+		tag_inc(tag);
+	}
+}
+EXPORT_SYMBOL_GPL(xas_init_tags);
+
 /**
  * xa_init_flags() - Initialise an empty XArray with flags.
  * @xa: XArray.
@@ -249,9 +829,19 @@ EXPORT_SYMBOL_GPL(xas_clear_tag);
  */
 void xa_init_flags(struct xarray *xa, gfp_t flags)
 {
+	unsigned int lock_type;
+	static struct lock_class_key xa_lock_irq;
+	static struct lock_class_key xa_lock_bh;
+
 	spin_lock_init(&xa->xa_lock);
 	xa->xa_flags = flags;
 	xa->xa_head = NULL;
+
+	lock_type = xa_lock_type(xa);
+	if (lock_type == XA_LOCK_IRQ)
+		lockdep_set_class(&xa->xa_lock, &xa_lock_irq);
+	else if (lock_type == XA_LOCK_BH)
+		lockdep_set_class(&xa->xa_lock, &xa_lock_bh);
 }
 EXPORT_SYMBOL(xa_init_flags);
 
@@ -278,6 +868,100 @@ void *xa_load(struct xarray *xa, unsigned long index)
 }
 EXPORT_SYMBOL(xa_load);
 
+static void *xas_result(struct xa_state *xas, void *curr)
+{
+	XA_NODE_BUG_ON(xas->xa_node, xa_is_internal(curr));
+	if (xas_error(xas))
+		curr = xas->xa_node;
+	return curr;
+}
+
+/**
+ * __xa_erase() - Erase this entry from the XArray while locked.
+ * @xa: XArray.
+ * @index: Index into array.
+ *
+ * If the entry at this index is a multi-index entry then all indices will
+ * be erased, and the entry will no longer be a multi-index entry.
+ * This function expects the xa_lock to be held on entry.
+ *
+ * Context: Any context.  Expects xa_lock to be held on entry.  May
+ * release and reacquire xa_lock if @gfp flags permit.
+ * Return: The old entry at this index.
+ */
+void *__xa_erase(struct xarray *xa, unsigned long index)
+{
+	XA_STATE(xas, xa, index);
+	return xas_result(&xas, xas_store(&xas, NULL));
+}
+EXPORT_SYMBOL_GPL(__xa_erase);
+
+/**
+ * xa_store() - Store this entry in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @entry: New entry.
+ * @gfp: Memory allocation flags.
+ *
+ * After this function returns, loads from this index will return @entry.
+ * Storing into an existing multislot entry updates the entry of every index.
+ * The tags associated with @index are unaffected unless @entry is %NULL.
+ *
+ * Context: Process context.  Takes and releases the xa_lock.  May sleep
+ * if the @gfp flags permit.
+ * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry
+ * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation
+ * failed.
+ */
+void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
+{
+	XA_STATE(xas, xa, index);
+	void *curr;
+
+	if (WARN_ON_ONCE(xa_is_internal(entry)))
+		return XA_ERROR(-EINVAL);
+
+	do {
+		xas_lock(&xas);
+		curr = xas_store(&xas, entry);
+		xas_unlock(&xas);
+	} while (xas_nomem(&xas, gfp));
+
+	return xas_result(&xas, curr);
+}
+EXPORT_SYMBOL(xa_store);
+
+/**
+ * __xa_store() - Store this entry in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @entry: New entry.
+ * @gfp: Memory allocation flags.
+ *
+ * You must already be holding the xa_lock when calling this function.
+ * It will drop the lock if needed to allocate memory, and then reacquire
+ * it afterwards.
+ *
+ * Context: Any context.  Expects xa_lock to be held on entry.  May
+ * release and reacquire xa_lock if @gfp flags permit.
+ * Return: The old entry at this index or xa_err() if an error happened.
+ */
+void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
+{
+	XA_STATE(xas, xa, index);
+	void *curr;
+
+	if (WARN_ON_ONCE(xa_is_internal(entry)))
+		return XA_ERROR(-EINVAL);
+
+	do {
+		curr = xas_store(&xas, entry);
+	} while (__xas_nomem(&xas, gfp));
+
+	return xas_result(&xas, curr);
+}
+EXPORT_SYMBOL(__xa_store);
+
 /**
  * __xa_set_tag() - Set this tag on this entry while locked.
  * @xa: XArray.
diff --git a/tools/include/linux/bitmap.h b/tools/include/linux/bitmap.h
index 63440cc8d618..48c208437bbd 100644
--- a/tools/include/linux/bitmap.h
+++ b/tools/include/linux/bitmap.h
@@ -15,6 +15,7 @@ void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
 		 const unsigned long *bitmap2, int bits);
 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
 		 const unsigned long *bitmap2, unsigned int bits);
+void bitmap_clear(unsigned long *map, unsigned int start, int len);
 
 #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
 
diff --git a/tools/include/linux/spinlock.h b/tools/include/linux/spinlock.h
index 622266b197d0..c934572d935c 100644
--- a/tools/include/linux/spinlock.h
+++ b/tools/include/linux/spinlock.h
@@ -37,4 +37,6 @@ static inline bool arch_spin_is_locked(arch_spinlock_t *mutex)
 	return true;
 }
 
+#include <linux/lockdep.h>
+
 #endif
diff --git a/tools/testing/radix-tree/Makefile b/tools/testing/radix-tree/Makefile
index 5d224c15f0fd..58b732d178c0 100644
--- a/tools/testing/radix-tree/Makefile
+++ b/tools/testing/radix-tree/Makefile
@@ -5,7 +5,7 @@ CFLAGS += -I. -I../../include -g -Og -Wall -D_LGPL_SOURCE -fsanitize=address \
 LDFLAGS += -fsanitize=address -fsanitize=undefined
 LDLIBS+= -lpthread -lurcu
 TARGETS = main idr-test multiorder xarray
-CORE_OFILES := xarray.o radix-tree.o idr.o linux.o test.o find_bit.o
+CORE_OFILES := xarray.o radix-tree.o idr.o linux.o test.o find_bit.o bitmap.o
 OFILES = main.o $(CORE_OFILES) regression1.o regression2.o regression3.o \
 	 tag_check.o multiorder.o idr-test.o iteration_check.o benchmark.o
 
diff --git a/tools/testing/radix-tree/bitmap.c b/tools/testing/radix-tree/bitmap.c
new file mode 100644
index 000000000000..66ec4a24a203
--- /dev/null
+++ b/tools/testing/radix-tree/bitmap.c
@@ -0,0 +1,23 @@
+/* lib/bitmap.c pulls in at least two other files. */
+
+#include <linux/bitmap.h>
+
+void bitmap_clear(unsigned long *map, unsigned int start, int len)
+{
+	unsigned long *p = map + BIT_WORD(start);
+	const unsigned int size = start + len;
+	int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
+	unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
+
+	while (len - bits_to_clear >= 0) {
+		*p &= ~mask_to_clear;
+		len -= bits_to_clear;
+		bits_to_clear = BITS_PER_LONG;
+		mask_to_clear = ~0UL;
+		p++;
+	}
+	if (len) {
+		mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
+		*p &= ~mask_to_clear;
+	}
+}
diff --git a/tools/testing/radix-tree/linux/kernel.h b/tools/testing/radix-tree/linux/kernel.h
index 5d06ac75a14d..4568248222ae 100644
--- a/tools/testing/radix-tree/linux/kernel.h
+++ b/tools/testing/radix-tree/linux/kernel.h
@@ -18,4 +18,8 @@
 #define pr_debug printk
 #define pr_cont printk
 
+#define __acquires(x)
+#define __releases(x)
+#define __must_hold(x)
+
 #endif /* _KERNEL_H */
diff --git a/tools/testing/radix-tree/linux/lockdep.h b/tools/testing/radix-tree/linux/lockdep.h
new file mode 100644
index 000000000000..565fccdfe6e9
--- /dev/null
+++ b/tools/testing/radix-tree/linux/lockdep.h
@@ -0,0 +1,11 @@
+#ifndef _LINUX_LOCKDEP_H
+#define _LINUX_LOCKDEP_H
+struct lock_class_key {
+	unsigned int a;
+};
+
+static inline void lockdep_set_class(spinlock_t *lock,
+					struct lock_class_key *key)
+{
+}
+#endif /* _LINUX_LOCKDEP_H */
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 12/74] xarray: Add XArray conditional store operations
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (10 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 11/74] xarray: Add XArray unconditional store operations Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 13/74] xarray: Add XArray iterators Matthew Wilcox
                   ` (62 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Like cmpxchg(), xa_cmpxchg will only store to the index if the current
entry matches the old entry.  It returns the current entry, which is
usually more useful than the errno returned by radix_tree_insert().
For the users who really only want the errno, the xa_insert() wrapper
provides a more convenient calling convention.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/xarray.h | 60 +++++++++++++++++++++++++++++++++++
 lib/test_xarray.c      | 20 ++++++++++++
 lib/xarray.c           | 71 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 151 insertions(+)

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 13e5c4084dcd..94b7f454a6a0 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -218,6 +218,8 @@ struct xarray {
 void xa_init_flags(struct xarray *, gfp_t flags);
 void *xa_load(struct xarray *, unsigned long index);
 void *xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
+void *xa_cmpxchg(struct xarray *, unsigned long index,
+			void *old, void *entry, gfp_t);
 bool xa_get_tag(struct xarray *, unsigned long index, xa_tag_t);
 void xa_set_tag(struct xarray *, unsigned long index, xa_tag_t);
 void xa_clear_tag(struct xarray *, unsigned long index, xa_tag_t);
@@ -277,6 +279,34 @@ static inline void *xa_erase(struct xarray *xa, unsigned long index)
 	return xa_store(xa, index, NULL, 0);
 }
 
+/**
+ * xa_insert() - Store this entry in the XArray unless another entry is
+ *			already present.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @entry: New entry.
+ * @gfp: Memory allocation flags.
+ *
+ * If you would rather see the existing entry in the array, use xa_cmpxchg().
+ * This function is for users who don't care what the entry is, only that
+ * one is present.
+ *
+ * Context: Process context.  Takes and releases the xa_lock.
+ *	    May sleep if the @gfp flags permit.
+ * Return: 0 if the store succeeded.  -EEXIST if another entry was present.
+ * 	   -ENOMEM if memory could not be allocated.
+ */
+static inline int xa_insert(struct xarray *xa, unsigned long index,
+		void *entry, gfp_t gfp)
+{
+	void *curr = xa_cmpxchg(xa, index, NULL, entry, gfp);
+	if (!curr)
+		return 0;
+	if (xa_is_err(curr))
+		return xa_err(curr);
+	return -EEXIST;
+}
+
 #define xa_trylock(xa)		spin_trylock(&(xa)->xa_lock)
 #define xa_lock(xa)		spin_lock(&(xa)->xa_lock)
 #define xa_unlock(xa)		spin_unlock(&(xa)->xa_lock)
@@ -296,9 +326,39 @@ static inline void *xa_erase(struct xarray *xa, unsigned long index)
  */
 void *__xa_erase(struct xarray *, unsigned long index);
 void *__xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
+void *__xa_cmpxchg(struct xarray *, unsigned long index, void *old,
+		void *entry, gfp_t);
 void __xa_set_tag(struct xarray *, unsigned long index, xa_tag_t);
 void __xa_clear_tag(struct xarray *, unsigned long index, xa_tag_t);
 
+/**
+ * __xa_insert() - Store this entry in the XArray unless another entry is
+ *			already present.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @entry: New entry.
+ * @gfp: Memory allocation flags.
+ *
+ * If you would rather see the existing entry in the array, use __xa_cmpxchg().
+ * This function is for users who don't care what the entry is, only that
+ * one is present.
+ *
+ * Context: Any context.  Expects xa_lock to be held on entry.  May
+ *	    release and reacquire xa_lock if the @gfp flags permit.
+ * Return: 0 if the store succeeded.  -EEXIST if another entry was present.
+ *	   -ENOMEM if memory could not be allocated.
+ */
+static inline int __xa_insert(struct xarray *xa, unsigned long index,
+		void *entry, gfp_t gfp)
+{
+	void *curr = __xa_cmpxchg(xa, index, NULL, entry, gfp);
+	if (!curr)
+		return 0;
+	if (xa_is_err(curr))
+		return xa_err(curr);
+	return -EEXIST;
+}
+
 /* Everything below here is the Advanced API.  Proceed with caution. */
 
 /*
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index cb6e9910e369..35fca5e23cbc 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -181,6 +181,25 @@ static void check_xa_shrink(struct xarray *xa)
 	XA_BUG_ON(xa, !xa_empty(xa));
 }
 
+static void check_cmpxchg(struct xarray *xa)
+{
+	void *FIVE = xa_mk_value(5);
+	void *SIX = xa_mk_value(6);
+	void *LOTS = xa_mk_value(12345678);
+
+	XA_BUG_ON(xa, !xa_empty(xa));
+	XA_BUG_ON(xa, xa_store_value(xa, 12345678, GFP_KERNEL) != NULL);
+	XA_BUG_ON(xa, xa_insert(xa, 12345678, xa, GFP_KERNEL) != -EEXIST);
+	XA_BUG_ON(xa, xa_cmpxchg(xa, 12345678, SIX, FIVE, GFP_KERNEL) != LOTS);
+	XA_BUG_ON(xa, xa_cmpxchg(xa, 12345678, LOTS, FIVE, GFP_KERNEL) != LOTS);
+	XA_BUG_ON(xa, xa_cmpxchg(xa, 12345678, FIVE, LOTS, GFP_KERNEL) != FIVE);
+	XA_BUG_ON(xa, xa_cmpxchg(xa, 5, FIVE, NULL, GFP_KERNEL) != NULL);
+	XA_BUG_ON(xa, xa_cmpxchg(xa, 5, NULL, FIVE, GFP_KERNEL) != NULL);
+	xa_erase_value(xa, 12345678);
+	xa_erase_value(xa, 5);
+	XA_BUG_ON(xa, !xa_empty(xa));
+}
+
 static void check_multi_store(struct xarray *xa)
 {
 	unsigned long i, j, k;
@@ -248,6 +267,7 @@ static int xarray_checks(void)
 	check_xa_load(&array);
 	check_xa_tag(&array);
 	check_xa_shrink(&array);
+	check_cmpxchg(&array);
 	check_multi_store(&array);
 
 	printk("XArray: %u of %u tests passed\n", tests_passed, tests_run);
diff --git a/lib/xarray.c b/lib/xarray.c
index 18043aee8a91..1a3a256cbb37 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -962,6 +962,77 @@ void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
 }
 EXPORT_SYMBOL(__xa_store);
 
+/**
+ * xa_cmpxchg() - Conditionally replace an entry in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @old: Old value to test against.
+ * @entry: New value to place in array.
+ * @gfp: Memory allocation flags.
+ *
+ * If the entry at @index is the same as @old, replace it with @entry.
+ * If the return value is equal to @old, then the exchange was successful.
+ *
+ * Context: Process context.  Takes and releases the xa_lock.  May sleep
+ * if the @gfp flags permit.
+ * Return: The old value at this index or xa_err() if an error happened.
+ */
+void *xa_cmpxchg(struct xarray *xa, unsigned long index,
+			void *old, void *entry, gfp_t gfp)
+{
+	XA_STATE(xas, xa, index);
+	void *curr;
+
+	if (WARN_ON_ONCE(xa_is_internal(entry)))
+		return XA_ERROR(-EINVAL);
+
+	do {
+		xas_lock(&xas);
+		curr = xas_load(&xas);
+		if (curr == old)
+			xas_store(&xas, entry);
+		xas_unlock(&xas);
+	} while (xas_nomem(&xas, gfp));
+
+	return xas_result(&xas, curr);
+}
+EXPORT_SYMBOL(xa_cmpxchg);
+
+/**
+ * __xa_cmpxchg() - Store this entry in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @old: Old value to test against.
+ * @entry: New entry.
+ * @gfp: Memory allocation flags.
+ *
+ * You must already be holding the xa_lock when calling this function.
+ * It will drop the lock if needed to allocate memory, and then reacquire
+ * it afterwards.
+ *
+ * Context: Any context.  Expects xa_lock to be held on entry.  May
+ * release and reacquire xa_lock if @gfp flags permit.
+ * Return: The old entry at this index or xa_err() if an error happened.
+ */
+void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
+			void *old, void *entry, gfp_t gfp)
+{
+	XA_STATE(xas, xa, index);
+	void *curr;
+
+	if (WARN_ON_ONCE(xa_is_internal(entry)))
+		return XA_ERROR(-EINVAL);
+
+	do {
+		curr = xas_load(&xas);
+		if (curr == old)
+			xas_store(&xas, entry);
+	} while (__xas_nomem(&xas, gfp));
+
+	return xas_result(&xas, curr);
+}
+EXPORT_SYMBOL(__xa_cmpxchg);
+
 /**
  * __xa_set_tag() - Set this tag on this entry while locked.
  * @xa: XArray.
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 13/74] xarray: Add XArray iterators
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (11 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 12/74] xarray: Add XArray conditional " Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 14/74] xarray: Extract entries from an XArray Matthew Wilcox
                   ` (61 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

The xa_for_each iterator allows the user to efficiently walk a range
of the array, executing the loop body once for each entry in that
range that matches the filter.  This commit also includes xa_find()
and xa_find_above() which are helper functions for xa_for_each() but
may also be useful in their own right.

In the xas family of functions, we have xas_for_each(), xas_find(),
xas_next_entry(), xas_for_each_tagged(), xas_find_tagged(),
xas_next_tagged() and xas_pause().

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/xarray.h | 169 +++++++++++++++++++++++++
 lib/test_xarray.c      | 128 +++++++++++++++++++
 lib/xarray.c           | 274 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 571 insertions(+)

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 94b7f454a6a0..0790b3b098f0 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -223,6 +223,10 @@ void *xa_cmpxchg(struct xarray *, unsigned long index,
 bool xa_get_tag(struct xarray *, unsigned long index, xa_tag_t);
 void xa_set_tag(struct xarray *, unsigned long index, xa_tag_t);
 void xa_clear_tag(struct xarray *, unsigned long index, xa_tag_t);
+void *xa_find(struct xarray *xa, unsigned long *index,
+		unsigned long max, xa_tag_t) __attribute__((nonnull(2)));
+void *xa_find_after(struct xarray *xa, unsigned long *index,
+		unsigned long max, xa_tag_t) __attribute__((nonnull(2)));
 
 /**
  * xa_init() - Initialise an empty XArray.
@@ -307,6 +311,35 @@ static inline int xa_insert(struct xarray *xa, unsigned long index,
 	return -EEXIST;
 }
 
+/**
+ * xa_for_each() - Iterate over a portion of an XArray.
+ * @xa: XArray.
+ * @entry: Entry retrieved from array.
+ * @index: Index of @entry.
+ * @max: Maximum index to retrieve from array.
+ * @filter: Selection criterion.
+ *
+ * Initialise @index to the lowest index you want to retrieve from the
+ * array.  During the iteration, @entry will have the value of the entry
+ * stored in @xa at @index.  The iteration will skip all entries in the
+ * array which do not match @filter.  You may modify @index during the
+ * iteration if you want to skip or reprocess indices.  It is safe to modify
+ * the array during the iteration.  At the end of the iteration, @entry will
+ * be set to NULL and @index will have a value less than or equal to max.
+ *
+ * xa_for_each() is O(n.log(n)) while xas_for_each() is O(n).  You have
+ * to handle your own locking with xas_for_each(), and if you have to unlock
+ * after each iteration, it will also end up being O(n.log(n)).  xa_for_each()
+ * will spin if it hits a retry entry; if you intend to see retry entries,
+ * you should use the xas_for_each() iterator instead.  The xas_for_each()
+ * iterator will expand into more inline code than xa_for_each().
+ *
+ * Context: Any context.  Takes and releases the RCU lock.
+ */
+#define xa_for_each(xa, entry, index, max, filter) \
+	for (entry = xa_find(xa, &index, max, filter); entry; \
+	     entry = xa_find_after(xa, &index, max, filter))
+
 #define xa_trylock(xa)		spin_trylock(&(xa)->xa_lock)
 #define xa_lock(xa)		spin_lock(&(xa)->xa_lock)
 #define xa_unlock(xa)		spin_unlock(&(xa)->xa_lock)
@@ -726,13 +759,16 @@ static inline bool xas_retry(struct xa_state *xas, const void *entry)
 
 void *xas_load(struct xa_state *);
 void *xas_store(struct xa_state *, void *entry);
+void *xas_find(struct xa_state *, unsigned long max);
 
 bool xas_get_tag(const struct xa_state *, xa_tag_t);
 void xas_set_tag(const struct xa_state *, xa_tag_t);
 void xas_clear_tag(const struct xa_state *, xa_tag_t);
+void *xas_find_tagged(struct xa_state *, unsigned long max, xa_tag_t);
 void xas_init_tags(const struct xa_state *);
 
 bool xas_nomem(struct xa_state *, gfp_t);
+void xas_pause(struct xa_state *);
 
 /**
  * xas_reload() - Refetch an entry from the xarray.
@@ -805,6 +841,139 @@ static inline void xas_set_update(struct xa_state *xas, xa_update_node_t update)
 	xas->xa_update = update;
 }
 
+/* Skip over any of these entries when iterating */
+static inline bool xa_iter_skip(const void *entry)
+{
+	return unlikely(!entry ||
+			(xa_is_internal(entry) && entry < XA_RETRY_ENTRY));
+}
+
+/**
+ * xas_next_entry() - Advance iterator to next present entry.
+ * @xas: XArray operation state.
+ * @max: Highest index to return.
+ *
+ * xas_next_entry() is an inline function to optimise xarray traversal for
+ * speed.  It is equivalent to calling xas_find(), and will call xas_find()
+ * for all the hard cases.
+ *
+ * Return: The next present entry after the one currently referred to by @xas.
+ */
+static inline void *xas_next_entry(struct xa_state *xas, unsigned long max)
+{
+	struct xa_node *node = xas->xa_node;
+	void *entry;
+
+	if (unlikely(xas_not_node(node) || node->shift))
+		return xas_find(xas, max);
+
+	do {
+		if (unlikely(xas->xa_index >= max))
+			return xas_find(xas, max);
+		if (unlikely(xas->xa_offset == XA_CHUNK_MASK))
+			return xas_find(xas, max);
+		xas->xa_index++;
+		xas->xa_offset++;
+		entry = xa_entry(xas->xa, node, xas->xa_offset);
+	} while (xa_iter_skip(entry));
+
+	return entry;
+}
+
+/* Private */
+static inline unsigned int xas_find_chunk(struct xa_state *xas, bool advance,
+		xa_tag_t tag)
+{
+	unsigned long *addr = xas->xa_node->tags[(__force unsigned)tag];
+	unsigned int offset = xas->xa_offset;
+
+	if (advance)
+		offset++;
+	if (XA_CHUNK_SIZE == BITS_PER_LONG) {
+		if (offset < XA_CHUNK_SIZE) {
+			unsigned long data = *addr & (~0UL << offset);
+			if (data)
+				return __ffs(data);
+		}
+		return XA_CHUNK_SIZE;
+	}
+
+	return find_next_bit(addr, XA_CHUNK_SIZE, offset);
+}
+
+/**
+ * xas_next_tagged() - Advance iterator to next tagged entry.
+ * @xas: XArray operation state.
+ * @max: Highest index to return.
+ * @tag: Tag to search for.
+ *
+ * xas_next_tagged() is an inline function to optimise xarray traversal for
+ * speed.  It is equivalent to calling xas_find_tagged(), and will call
+ * xas_find_tagged() for all the hard cases.
+ *
+ * Return: The next tagged entry after the one currently referred to by @xas.
+ */
+static inline void *xas_next_tagged(struct xa_state *xas, unsigned long max,
+								xa_tag_t tag)
+{
+	struct xa_node *node = xas->xa_node;
+	unsigned int offset;
+
+	if (unlikely(xas_not_node(node) || node->shift))
+		return xas_find_tagged(xas, max, tag);
+	offset = xas_find_chunk(xas, true, tag);
+	xas->xa_offset = offset;
+	xas->xa_index = (xas->xa_index & ~XA_CHUNK_MASK) + offset;
+	if (xas->xa_index > max)
+		return NULL;
+	if (offset == XA_CHUNK_SIZE)
+		return xas_find_tagged(xas, max, tag);
+	return xa_entry(xas->xa, node, offset);
+}
+
+/*
+ * If iterating while holding a lock, drop the lock and reschedule
+ * every %XA_CHECK_SCHED loops.
+ */
+enum {
+	XA_CHECK_SCHED = 4096,
+};
+
+/**
+ * xas_for_each() - Iterate over a range of an XArray.
+ * @xas: XArray operation state.
+ * @entry: Entry retrieved from the array.
+ * @max: Maximum index to retrieve from array.
+ *
+ * The loop body will be executed for each entry present in the xarray
+ * between the current xas position and @max.  @entry will be set to
+ * the entry retrieved from the xarray.  It is safe to delete entries
+ * from the array in the loop body.  You should hold either the RCU lock
+ * or the xa_lock while iterating.  If you need to drop the lock, call
+ * xas_pause() first.
+ */
+#define xas_for_each(xas, entry, max) \
+	for (entry = xas_find(xas, max); entry; \
+	     entry = xas_next_entry(xas, max))
+
+/**
+ * xas_for_each_tagged() - Iterate over a range of an XArray.
+ * @xas: XArray operation state.
+ * @entry: Entry retrieved from the array.
+ * @max: Maximum index to retrieve from array.
+ * @tag: Tag to search for.
+ *
+ * The loop body will be executed for each tagged entry in the xarray
+ * between the current xas position and @max.  @entry will be set to
+ * the entry retrieved from the xarray.  It is safe to delete entries
+ * from the array in the loop body.  You should hold either the RCU lock
+ * or the xa_lock while iterating.  If you need to drop the lock, call
+ * xas_pause() first.
+ */
+#define xas_for_each_tagged(xas, entry, max, tag) \
+	for (entry = xas_find_tagged(xas, max, tag); entry; \
+	     entry = xas_next_tagged(xas, max, tag))
+
 /* Internal functions, mostly shared between radix-tree.c, xarray.c and idr.c */
 void xas_destroy(struct xa_state *);
 
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index 35fca5e23cbc..a6a3705165ca 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -73,6 +73,31 @@ static void check_xa_err(struct xarray *xa)
 //	XA_BUG_ON(xa, xa_err(xa_store(xa, 0, xa_mk_internal(0), 0)) != -EINVAL);
 }
 
+static void check_xas_retry(struct xarray *xa)
+{
+	XA_STATE(xas, xa, 0);
+
+	xa_store_value(xa, 0, GFP_KERNEL);
+	xa_store_value(xa, 1, GFP_KERNEL);
+
+	XA_BUG_ON(xa, xas_find(&xas, ULONG_MAX) != xa_mk_value(0));
+	xa_erase_value(xa, 1);
+	XA_BUG_ON(xa, !xa_is_retry(xas_reload(&xas)));
+	XA_BUG_ON(xa, xas_retry(&xas, NULL));
+	XA_BUG_ON(xa, xas_retry(&xas, xa_mk_value(0)));
+	xas_reset(&xas);
+	XA_BUG_ON(xa, xas.xa_node != XAS_RESTART);
+	XA_BUG_ON(xa, xas_next_entry(&xas, ULONG_MAX) != xa_mk_value(0));
+	XA_BUG_ON(xa, xas.xa_node != NULL);
+
+	XA_BUG_ON(xa, xa_store_value(xa, 1, GFP_KERNEL) != NULL);
+	XA_BUG_ON(xa, !xa_is_internal(xas_reload(&xas)));
+	xas.xa_node = XAS_RESTART;
+	XA_BUG_ON(xa, xas_next_entry(&xas, ULONG_MAX) != xa_mk_value(0));
+	xa_erase_value(xa, 0);
+	xa_erase_value(xa, 1);
+}
+
 static void check_xa_load(struct xarray *xa)
 {
 	unsigned long i, j;
@@ -200,6 +225,37 @@ static void check_cmpxchg(struct xarray *xa)
 	XA_BUG_ON(xa, !xa_empty(xa));
 }
 
+static void check_xas_erase(struct xarray *xa)
+{
+	XA_STATE(xas, xa, 0);
+	void *entry;
+	unsigned long i, j;
+
+	for (i = 0; i < 200; i++) {
+		for (j = i; j < 2 * i + 17; j++) {
+			xas_set(&xas, j);
+			do {
+				xas_store(&xas, xa_mk_value(j));
+			} while (xas_nomem(&xas, GFP_KERNEL));
+		}
+
+		xas_set(&xas, ULONG_MAX);
+		do {
+			xas_store(&xas, xa_mk_value(0));
+		} while (xas_nomem(&xas, GFP_KERNEL));
+		xas_store(&xas, NULL);
+
+		xas_set(&xas, 0);
+		j = i;
+		xas_for_each(&xas, entry, ULONG_MAX) {
+			XA_BUG_ON(xa, entry != xa_mk_value(j));
+			xas_store(&xas, NULL);
+			j++;
+		}
+		XA_BUG_ON(xa, !xa_empty(xa));
+	}
+}
+
 static void check_multi_store(struct xarray *xa)
 {
 	unsigned long i, j, k;
@@ -259,16 +315,88 @@ static void check_multi_store(struct xarray *xa)
 	}
 }
 
+static void check_multi_find(struct xarray *xa)
+{
+	unsigned long index;
+
+	xa_store_order(xa, 12, 2, xa_mk_value(12), GFP_KERNEL);
+	XA_BUG_ON(xa, xa_store_value(xa, 16, GFP_KERNEL) != NULL);
+
+	index = 0;
+	XA_BUG_ON(xa, xa_find(xa, &index, ULONG_MAX, XA_PRESENT) !=
+			xa_mk_value(12));
+	XA_BUG_ON(xa, index != 12);
+	index = 13;
+	XA_BUG_ON(xa, xa_find(xa, &index, ULONG_MAX, XA_PRESENT) !=
+			xa_mk_value(12));
+	XA_BUG_ON(xa, (index < 12) || (index >= 16));
+	XA_BUG_ON(xa, xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT) !=
+			xa_mk_value(16));
+	XA_BUG_ON(xa, index != 16);
+
+	xa_erase_value(xa, 12);
+	xa_erase_value(xa, 16);
+	XA_BUG_ON(xa, !xa_empty(xa));
+}
+
+static void check_find(struct xarray *xa)
+{
+	unsigned long i, j, k;
+
+	XA_BUG_ON(xa, !xa_empty(xa));
+
+	for (i = 0; i < 100; i++) {
+		XA_BUG_ON(xa, xa_store_value(xa, i, GFP_KERNEL) != NULL);
+		xa_set_tag(xa, i, XA_TAG_0);
+		for (j = 0; j < i; j++) {
+			XA_BUG_ON(xa, xa_store_value(xa, j, GFP_KERNEL) !=
+					NULL);
+			xa_set_tag(xa, j, XA_TAG_0);
+			for (k = 0; k < 100; k++) {
+				unsigned long index = k;
+				void *entry = xa_find(xa, &index, ULONG_MAX,
+								XA_PRESENT);
+				if (k <= j)
+					XA_BUG_ON(xa, index != j);
+				else if (k <= i)
+					XA_BUG_ON(xa, index != i);
+				else
+					XA_BUG_ON(xa, entry != NULL);
+
+				index = k;
+				entry = xa_find(xa, &index, ULONG_MAX,
+								XA_TAG_0);
+				if (k <= j)
+					XA_BUG_ON(xa, index != j);
+				else if (k <= i)
+					XA_BUG_ON(xa, index != i);
+				else
+					XA_BUG_ON(xa, entry != NULL);
+			}
+			xa_erase_value(xa, j);
+			XA_BUG_ON(xa, xa_get_tag(xa, j, XA_TAG_0));
+			XA_BUG_ON(xa, !xa_get_tag(xa, i, XA_TAG_0));
+		}
+		xa_erase_value(xa, i);
+		XA_BUG_ON(xa, xa_get_tag(xa, i, XA_TAG_0));
+	}
+	XA_BUG_ON(xa, !xa_empty(xa));
+	check_multi_find(xa);
+}
+
 static int xarray_checks(void)
 {
 	DEFINE_XARRAY(array);
 
 	check_xa_err(&array);
+	check_xas_retry(&array);
 	check_xa_load(&array);
 	check_xa_tag(&array);
 	check_xa_shrink(&array);
+	check_xas_erase(&array);
 	check_cmpxchg(&array);
 	check_multi_store(&array);
+	check_find(&array);
 
 	printk("XArray: %u of %u tests passed\n", tests_passed, tests_run);
 	return (tests_run != tests_passed) ? 0 : -EINVAL;
diff --git a/lib/xarray.c b/lib/xarray.c
index 1a3a256cbb37..8756ca22363e 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -103,6 +103,11 @@ static unsigned int get_offset(unsigned long index, struct xa_node *node)
 	return (index >> node->shift) & XA_CHUNK_MASK;
 }
 
+static void xas_set_offset(struct xa_state *xas)
+{
+	xas->xa_offset = get_offset(xas->xa_index, xas->xa_node);
+}
+
 /* move the index either forwards (find) or backwards (sibling slot) */
 static void xas_move_index(struct xa_state *xas, unsigned long offset)
 {
@@ -111,6 +116,12 @@ static void xas_move_index(struct xa_state *xas, unsigned long offset)
 	xas->xa_index += offset << shift;
 }
 
+static void xas_advance(struct xa_state *xas)
+{
+	xas->xa_offset++;
+	xas_move_index(xas, xas->xa_offset);
+}
+
 static void *set_bounds(struct xa_state *xas)
 {
 	xas->xa_node = XAS_BOUNDS;
@@ -816,6 +827,191 @@ void xas_init_tags(const struct xa_state *xas)
 }
 EXPORT_SYMBOL_GPL(xas_init_tags);
 
+/**
+ * xas_pause() - Pause a walk to drop a lock.
+ * @xas: XArray operation state.
+ *
+ * Some users need to pause a walk and drop the lock they're holding in
+ * order to yield to a higher priority thread or carry out an operation
+ * on an entry.  Those users should call this function before they drop
+ * the lock.  It resets the @xas to be suitable for the next iteration
+ * of the loop after the user has reacquired the lock.  If most entries
+ * found during a walk require you to call xas_pause(), the xa_for_each()
+ * iterator may be more appropriate.
+ *
+ * Note that xas_pause() only works for forward iteration.  If a user needs
+ * to pause a reverse iteration, we will need a xas_pause_rev().
+ */
+void xas_pause(struct xa_state *xas)
+{
+	struct xa_node *node = xas->xa_node;
+
+	if (xas_invalid(xas))
+		return;
+
+	if (node) {
+		unsigned int offset = xas->xa_offset;
+		while (++offset < XA_CHUNK_SIZE) {
+			if (!xa_is_sibling(xa_entry(xas->xa, node, offset)))
+				break;
+		}
+		xas->xa_index += (offset - xas->xa_offset) << node->shift;
+	} else {
+		xas->xa_index++;
+	}
+	xas->xa_node = XAS_RESTART;
+}
+EXPORT_SYMBOL_GPL(xas_pause);
+
+/**
+ * xas_find() - Find the next present entry in the XArray.
+ * @xas: XArray operation state.
+ * @max: Highest index to return.
+ *
+ * If the xas has not yet been walked to an entry, return the entry
+ * which has an index >= xas.xa_index.  If it has been walked, the entry
+ * currently being pointed at has been processed, and so we move to the
+ * next entry.
+ *
+ * If no entry is found and the array is smaller than @max, the iterator
+ * is set to the smallest index not yet in the array.  This allows @xas
+ * to be immediately passed to xas_store().
+ *
+ * Return: The entry, if found, otherwise NULL.
+ */
+void *xas_find(struct xa_state *xas, unsigned long max)
+{
+	void *entry;
+
+	if (xas_error(xas))
+		return NULL;
+
+	if (!xas->xa_node) {
+		xas->xa_index = 1;
+		return set_bounds(xas);
+	} else if (xas_top(xas->xa_node)) {
+		entry = xas_load(xas);
+		if (entry || xas_not_node(xas->xa_node))
+			return entry;
+	}
+
+	xas_advance(xas);
+
+	while (xas->xa_node && (xas->xa_index <= max)) {
+		if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
+			xas->xa_offset = xas->xa_node->offset + 1;
+			xas->xa_node = xa_parent(xas->xa, xas->xa_node);
+			continue;
+		}
+
+		entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
+		if (xa_is_node(entry)) {
+			xas->xa_node = xa_to_node(entry);
+			xas->xa_offset = 0;
+			continue;
+		}
+		if (!xa_iter_skip(entry))
+			return entry;
+
+		xas_advance(xas);
+	}
+
+	if (!xas->xa_node)
+		xas->xa_node = XAS_BOUNDS;
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(xas_find);
+
+/**
+ * xas_find_tagged() - Find the next tagged entry in the XArray.
+ * @xas: XArray operation state.
+ * @max: Highest index to return.
+ * @tag: Tag number to search for.
+ *
+ * If the xas has not yet been walked to an entry, return the tagged entry
+ * which has an index >= xas.xa_index.  If it has been walked, the entry
+ * currently being pointed at has been processed, and so we move to the
+ * next tagged entry.
+ *
+ * If no tagged entry is found and the array is smaller than @max, @xas is
+ * set to the bounds state and xas->xa_index is set to the smallest index
+ * not yet in the array.  This allows @xas to be immediately passed to
+ * xas_store().
+ *
+ * Return: The entry, if found, otherwise %NULL.
+ */
+void *xas_find_tagged(struct xa_state *xas, unsigned long max, xa_tag_t tag)
+{
+	bool advance = true;
+	unsigned int offset;
+	void *entry;
+
+	if (xas_error(xas))
+		return NULL;
+
+	if (!xas->xa_node) {
+		xas->xa_index = 1;
+		goto out;
+	} else if (xas_top(xas->xa_node)) {
+		advance = false;
+		entry = xa_head(xas->xa);
+		if (xas->xa_index > max_index(entry))
+			goto out;
+		if (!xa_is_node(entry)) {
+			if (xa_tagged(xas->xa, tag)) {
+				xas->xa_node = NULL;
+				return entry;
+			}
+			xas->xa_index = 1;
+			goto out;
+		}
+		xas->xa_node = xa_to_node(entry);
+		xas->xa_offset = xas->xa_index >> xas->xa_node->shift;
+	}
+
+	while (xas->xa_index <= max) {
+		if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
+			xas->xa_offset = xas->xa_node->offset + 1;
+			xas->xa_node = xa_parent(xas->xa, xas->xa_node);
+			if (!xas->xa_node)
+				break;
+			advance = false;
+			continue;
+		}
+
+		if (!advance) {
+			entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
+			if (xa_is_sibling(entry)) {
+				xas->xa_offset = xa_to_sibling(entry);
+				xas_move_index(xas, xas->xa_offset);
+			}
+		}
+
+		offset = xas_find_chunk(xas, advance, tag);
+		if (offset > xas->xa_offset) {
+			advance = false;
+			xas_move_index(xas, offset);
+			xas->xa_offset = offset;
+			if (offset == XA_CHUNK_SIZE)
+				continue;
+			if (xas->xa_index > max)
+				break;
+		}
+
+		entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
+		if (!xa_is_node(entry))
+			return entry;
+		xas->xa_node = xa_to_node(entry);
+		xas_set_offset(xas);
+	}
+
+ out:
+	if (!xas->xa_node)
+		xas->xa_node = XAS_BOUNDS;
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(xas_find_tagged);
+
 /**
  * xa_init_flags() - Initialise an empty XArray with flags.
  * @xa: XArray.
@@ -1139,6 +1335,84 @@ void xa_clear_tag(struct xarray *xa, unsigned long index, xa_tag_t tag)
 }
 EXPORT_SYMBOL(xa_clear_tag);
 
+/**
+ * xa_find() - Search the XArray for an entry.
+ * @xa: XArray.
+ * @indexp: Pointer to an index.
+ * @max: Maximum index to search to.
+ * @filter: Selection criterion.
+ *
+ * Finds the entry in @xa which matches the @filter, and has the lowest
+ * index that is at least @indexp and no more than @max.
+ * If an entry is found, @indexp is updated to be the index of the entry.
+ * This function is protected by the RCU read lock, so it may not find
+ * entries which are being simultaneously added.  It will not return an
+ * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
+ *
+ * Context: Any context.  Takes and releases the RCU lock.
+ * Return: The entry, if found, otherwise NULL.
+ */
+void *xa_find(struct xarray *xa, unsigned long *indexp,
+			unsigned long max, xa_tag_t filter)
+{
+	XA_STATE(xas, xa, *indexp);
+	void *entry;
+
+	rcu_read_lock();
+	do {
+		if ((__force unsigned int)filter < XA_MAX_TAGS)
+			entry = xas_find_tagged(&xas, max, filter);
+		else
+			entry = xas_find(&xas, max);
+	} while (xas_retry(&xas, entry));
+	rcu_read_unlock();
+
+	if (entry)
+		*indexp = xas.xa_index;
+	return entry;
+}
+EXPORT_SYMBOL(xa_find);
+
+/**
+ * xa_find_after() - Search the XArray for a present entry.
+ * @xa: XArray.
+ * @indexp: Pointer to an index.
+ * @max: Maximum index to search to.
+ * @filter: Selection criterion.
+ *
+ * Finds the entry in @xa which matches the @filter and has the lowest
+ * index that is above @indexp and no more than @max.
+ * If an entry is found, @indexp is updated to be the index of the entry.
+ * This function is protected by the RCU read lock, so it may miss entries
+ * which are being simultaneously added.  It will not return an
+ * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
+ *
+ * Context: Any context.  Takes and releases the RCU lock.
+ * Return: The pointer, if found, otherwise NULL.
+ */
+void *xa_find_after(struct xarray *xa, unsigned long *indexp,
+			unsigned long max, xa_tag_t filter)
+{
+	XA_STATE(xas, xa, *indexp + 1);
+	void *entry;
+
+	rcu_read_lock();
+	do {
+		if ((__force unsigned int)filter < XA_MAX_TAGS)
+			entry = xas_find_tagged(&xas, max, filter);
+		else
+			entry = xas_find(&xas, max);
+		if (*indexp >= xas.xa_index)
+			entry = xas_next_entry(&xas, max);
+	} while (xas_retry(&xas, entry));
+	rcu_read_unlock();
+
+	if (entry)
+		*indexp = xas.xa_index;
+	return entry;
+}
+EXPORT_SYMBOL(xa_find_after);
+
 #ifdef XA_DEBUG
 void xa_dump_node(const struct xa_node *node)
 {
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 14/74] xarray: Extract entries from an XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (12 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 13/74] xarray: Add XArray iterators Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 15/74] xarray: Destroy " Matthew Wilcox
                   ` (60 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

The xa_extract function combines the functionality of
radix_tree_gang_lookup() and radix_tree_gang_lookup_tagged().
It extracts entries matching the specified filter into a normal array.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/xarray.h |  2 ++
 lib/xarray.c           | 80 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+)

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 0790b3b098f0..6f398732b664 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -227,6 +227,8 @@ void *xa_find(struct xarray *xa, unsigned long *index,
 		unsigned long max, xa_tag_t) __attribute__((nonnull(2)));
 void *xa_find_after(struct xarray *xa, unsigned long *index,
 		unsigned long max, xa_tag_t) __attribute__((nonnull(2)));
+unsigned int xa_extract(struct xarray *, void **dst, unsigned long start,
+		unsigned long max, unsigned int n, xa_tag_t);
 
 /**
  * xa_init() - Initialise an empty XArray.
diff --git a/lib/xarray.c b/lib/xarray.c
index 8756ca22363e..1e15ead40d78 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1413,6 +1413,86 @@ void *xa_find_after(struct xarray *xa, unsigned long *indexp,
 }
 EXPORT_SYMBOL(xa_find_after);
 
+static unsigned int xas_extract_present(struct xa_state *xas, void **dst,
+			unsigned long max, unsigned int n)
+{
+	void *entry;
+	unsigned int i = 0;
+
+	rcu_read_lock();
+	xas_for_each(xas, entry, max) {
+		if (xas_retry(xas, entry))
+			continue;
+		dst[i++] = entry;
+		if (i == n)
+			break;
+	}
+	rcu_read_unlock();
+
+	return i;
+}
+
+static unsigned int xas_extract_tag(struct xa_state *xas, void **dst,
+			unsigned long max, unsigned int n, xa_tag_t tag)
+{
+	void *entry;
+	unsigned int i = 0;
+
+	rcu_read_lock();
+	xas_for_each_tagged(xas, entry, max, tag) {
+		if (xas_retry(xas, entry))
+			continue;
+		dst[i++] = entry;
+		if (i == n)
+			break;
+	}
+	rcu_read_unlock();
+
+	return i;
+}
+
+/**
+ * xa_extract() - Copy selected entries from the XArray into a normal array.
+ * @xa: The source XArray to copy from.
+ * @dst: The buffer to copy entries into.
+ * @start: The first index in the XArray eligible to be selected.
+ * @max: The last index in the XArray eligible to be selected.
+ * @n: The maximum number of entries to copy.
+ * @filter: Selection criterion.
+ *
+ * Copies up to @n entries that match @filter from the XArray.  The
+ * copied entries will have indices between @start and @max, inclusive.
+ *
+ * The @filter may be an XArray tag value, in which case entries which are
+ * tagged with that tag will be copied.  It may also be %XA_PRESENT, in
+ * which case non-NULL entries will be copied.
+ *
+ * The entries returned may not represent a snapshot of the XArray at a
+ * moment in time.  For example, if another thread stores to index 5, then
+ * index 10, calling xa_extract() may return the old contents of index 5
+ * and the new contents of index 10.  Indices not modified while this
+ * function is running will not be skipped.
+ *
+ * If you need stronger guarantees, holding the xa_lock across calls to this
+ * function will prevent concurrent modification.
+ *
+ * Context: Any context.  Takes and releases the RCU lock.
+ * Return: The number of entries copied.
+ */
+unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
+			unsigned long max, unsigned int n, xa_tag_t filter)
+{
+	XA_STATE(xas, xa, start);
+
+	if (!n)
+		return 0;
+
+	if ((__force unsigned int)filter < XA_MAX_TAGS)
+		return xas_extract_tag(&xas, dst, max, n, filter);
+	return xas_extract_present(&xas, dst, max, n);
+}
+EXPORT_SYMBOL(xa_extract);
+
 #ifdef XA_DEBUG
 void xa_dump_node(const struct xa_node *node)
 {
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 15/74] xarray: Destroy an XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (13 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 14/74] xarray: Extract entries from an XArray Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 16/74] xarray: Step through " Matthew Wilcox
                   ` (59 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

This function frees all the internal memory allocated to the xarray
and reinitialises it to be empty.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/xarray.h |  1 +
 lib/xarray.c           | 28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 6f398732b664..fa36a0670988 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -229,6 +229,7 @@ void *xa_find_after(struct xarray *xa, unsigned long *index,
 		unsigned long max, xa_tag_t) __attribute__((nonnull(2)));
 unsigned int xa_extract(struct xarray *, void **dst, unsigned long start,
 		unsigned long max, unsigned int n, xa_tag_t);
+void xa_destroy(struct xarray *);
 
 /**
  * xa_init() - Initialise an empty XArray.
diff --git a/lib/xarray.c b/lib/xarray.c
index 1e15ead40d78..e90ba76404ae 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1493,6 +1493,34 @@ unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
 }
 EXPORT_SYMBOL(xa_extract);
 
+/**
+ * xa_destroy() - Free all internal data structures.
+ * @xa: XArray.
+ *
+ * After calling this function, the XArray is empty and has freed all memory
+ * allocated for its internal data structures.  You are responsible for
+ * freeing the objects referenced by the XArray.
+ *
+ * Context: Any context.  Takes and releases the xa_lock, interrupt-safe.
+ */
+void xa_destroy(struct xarray *xa)
+{
+	XA_STATE(xas, xa, 0);
+	unsigned long flags;
+	void *entry;
+
+	xas.xa_node = NULL;
+	xas_lock_irqsave(&xas, flags);
+	entry = xa_head_locked(xa);
+	RCU_INIT_POINTER(xa->xa_head, NULL);
+	xas_init_tags(&xas);
+	/* lockdep checks we're still holding the lock in xas_free_nodes() */
+	if (xa_is_node(entry))
+		xas_free_nodes(&xas, xa_to_node(entry));
+	xas_unlock_irqrestore(&xas, flags);
+}
+EXPORT_SYMBOL(xa_destroy);
+
 #ifdef XA_DEBUG
 void xa_dump_node(const struct xa_node *node)
 {
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 16/74] xarray: Step through an XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (14 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 15/74] xarray: Destroy " Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 17/74] xarray: Add xas_for_each_conflict Matthew Wilcox
                   ` (58 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

The xas_next and xas_prev functions move the xas index by one position,
and adjust the rest of the iterator state to match it.  This is more
efficient than calling xas_set() as it keeps the iterator at the leaves
of the tree instead of walking the iterator from the root each time.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/xarray.h |  67 +++++++++++++++++++++++++
 lib/test_xarray.c      | 109 +++++++++++++++++++++++++++++++++++++++++
 lib/xarray.c           |  74 ++++++++++++++++++++++++++++
 3 files changed, 250 insertions(+)

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index fa36a0670988..921d41034d7d 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -719,6 +719,12 @@ static inline bool xas_not_node(struct xa_node *node)
 	return ((unsigned long)node & 3) || !node;
 }
 
+/* True if the node represents RESTART or an error */
+static inline bool xas_frozen(struct xa_node *node)
+{
+	return (unsigned long)node & 2;
+}
+
 /* True if the node represents head-of-tree, RESTART or BOUNDS */
 static inline bool xas_top(struct xa_node *node)
 {
@@ -977,6 +983,67 @@ enum {
 	for (entry = xas_find_tagged(xas, max, tag); entry; \
 	     entry = xas_next_tagged(xas, max, tag))
 
+void *__xas_next(struct xa_state *);
+void *__xas_prev(struct xa_state *);
+
+/**
+ * xas_prev() - Move iterator to previous index.
+ * @xas: XArray operation state.
+ *
+ * If the @xas was in an error state, it will remain in an error state
+ * and this function will return %NULL.  If the @xas has never been walked,
+ * it will have the effect of calling xas_load().  Otherwise one will be
+ * subtracted from the index and the state will be walked to the correct
+ * location in the array for the next operation.
+ *
+ * If the iterator was referencing index 0, this function wraps
+ * around to %ULONG_MAX.
+ *
+ * Return: The entry at the new index.  This may be %NULL or an internal
+ * entry.
+ */
+static inline void *xas_prev(struct xa_state *xas)
+{
+	struct xa_node *node = xas->xa_node;
+
+	if (unlikely(xas_not_node(node) || node->shift ||
+				xas->xa_offset == 0))
+		return __xas_prev(xas);
+
+	xas->xa_index--;
+	xas->xa_offset--;
+	return xa_entry(xas->xa, node, xas->xa_offset);
+}
+
+/**
+ * xas_next() - Move state to next index.
+ * @xas: XArray operation state.
+ *
+ * If the @xas was in an error state, it will remain in an error state
+ * and this function will return %NULL.  If the @xas has never been walked,
+ * it will have the effect of calling xas_load().  Otherwise one will be
+ * added to the index and the state will be walked to the correct
+ * location in the array for the next operation.
+ *
+ * If the iterator was referencing index %ULONG_MAX, this function wraps
+ * around to 0.
+ *
+ * Return: The entry at the new index.  This may be %NULL or an internal
+ * entry.
+ */
+static inline void *xas_next(struct xa_state *xas)
+{
+	struct xa_node *node = xas->xa_node;
+
+	if (unlikely(xas_not_node(node) || node->shift ||
+				xas->xa_offset == XA_CHUNK_MASK))
+		return __xas_next(xas);
+
+	xas->xa_index++;
+	xas->xa_offset++;
+	return xa_entry(xas->xa, node, xas->xa_offset);
+}
+
 /* Internal functions, mostly shared between radix-tree.c, xarray.c and idr.c */
 void xas_destroy(struct xa_state *);
 
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index a6a3705165ca..e74ade12c663 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -384,6 +384,114 @@ static void check_find(struct xarray *xa)
 	check_multi_find(xa);
 }
 
+static void check_move_small(struct xarray *xa, unsigned long idx)
+{
+	XA_STATE(xas, xa, 0);
+	unsigned long i;
+
+	xa_store_value(xa, 0, GFP_KERNEL);
+	xa_store_value(xa, idx, GFP_KERNEL);
+
+	for (i = 0; i < idx * 4; i++) {
+		void *entry = xas_next(&xas);
+		if (i <= idx)
+			XA_BUG_ON(xa, xas.xa_node == XAS_RESTART);
+		XA_BUG_ON(xa, xas.xa_index != i);
+		if (i == 0 || i == idx)
+			XA_BUG_ON(xa, entry != xa_mk_value(i));
+		else
+			XA_BUG_ON(xa, entry != NULL);
+	}
+	xas_next(&xas);
+	XA_BUG_ON(xa, xas.xa_index != i);
+
+	do {
+		void *entry = xas_prev(&xas);
+		i--;
+		if (i <= idx)
+			XA_BUG_ON(xa, xas.xa_node == XAS_RESTART);
+		XA_BUG_ON(xa, xas.xa_index != i);
+		if (i == 0 || i == idx)
+			XA_BUG_ON(xa, entry != xa_mk_value(i));
+		else
+			XA_BUG_ON(xa, entry != NULL);
+	} while (i > 0);
+
+	xas_set(&xas, ULONG_MAX);
+	XA_BUG_ON(xa, xas_next(&xas) != NULL);
+	XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
+	XA_BUG_ON(xa, xas_next(&xas) != xa_mk_value(0));
+	XA_BUG_ON(xa, xas.xa_index != 0);
+	XA_BUG_ON(xa, xas_prev(&xas) != NULL);
+	XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
+
+	xa_erase_value(xa, 0);
+	xa_erase_value(xa, idx);
+	XA_BUG_ON(xa, !xa_empty(xa));
+}
+
+static void check_move(struct xarray *xa)
+{
+	XA_STATE(xas, xa, (1 << 16) - 1);
+	unsigned long i;
+
+	for (i = 0; i < (1 << 16); i++)
+		XA_BUG_ON(xa, xa_store_value(xa, i, GFP_KERNEL) != NULL);
+
+	do {
+		void *entry = xas_prev(&xas);
+		i--;
+		XA_BUG_ON(xa, entry != xa_mk_value(i));
+		XA_BUG_ON(xa, i != xas.xa_index);
+	} while (i != 0);
+
+	XA_BUG_ON(xa, xas_prev(&xas) != NULL);
+	XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
+
+	do {
+		void *entry = xas_next(&xas);
+		XA_BUG_ON(xa, entry != xa_mk_value(i));
+		XA_BUG_ON(xa, i != xas.xa_index);
+		i++;
+	} while (i < (1 << 16));
+
+	for (i = (1 << 8); i < (1 << 15); i++)
+		xa_erase_value(xa, i);
+
+	i = xas.xa_index;
+
+	do {
+		void *entry = xas_prev(&xas);
+		i--;
+		if ((i < (1 << 8)) || (i >= (1 << 15)))
+			XA_BUG_ON(xa, entry != xa_mk_value(i));
+		else
+			XA_BUG_ON(xa, entry != NULL);
+		XA_BUG_ON(xa, i != xas.xa_index);
+	} while (i != 0);
+
+	XA_BUG_ON(xa, xas_prev(&xas) != NULL);
+	XA_BUG_ON(xa, xas.xa_index != ULONG_MAX);
+
+	do {
+		void *entry = xas_next(&xas);
+		if ((i < (1 << 8)) || (i >= (1 << 15)))
+			XA_BUG_ON(xa, entry != xa_mk_value(i));
+		else
+			XA_BUG_ON(xa, entry != NULL);
+		XA_BUG_ON(xa, i != xas.xa_index);
+		i++;
+	} while (i < (1 << 16));
+
+	xa_destroy(xa);
+
+	for (i = 0; i < 16; i++)
+		check_move_small(xa, 1UL << i);
+
+	for (i = 2; i < 16; i++)
+		check_move_small(xa, (1UL << i) - 1);
+}
+
 static int xarray_checks(void)
 {
 	DEFINE_XARRAY(array);
@@ -397,6 +505,7 @@ static int xarray_checks(void)
 	check_cmpxchg(&array);
 	check_multi_store(&array);
 	check_find(&array);
+	check_move(&array);
 
 	printk("XArray: %u of %u tests passed\n", tests_passed, tests_run);
 	return (tests_run != tests_passed) ? 0 : -EINVAL;
diff --git a/lib/xarray.c b/lib/xarray.c
index e90ba76404ae..ab1b6786711e 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -863,6 +863,80 @@ void xas_pause(struct xa_state *xas)
 }
 EXPORT_SYMBOL_GPL(xas_pause);
 
+/*
+ * __xas_prev() - Find the previous entry in the XArray.
+ * @xas: XArray operation state.
+ *
+ * Helper function for xas_prev() which handles all the complex cases
+ * out of line.
+ */
+void *__xas_prev(struct xa_state *xas)
+{
+	void *entry;
+
+	if (!xas_frozen(xas->xa_node))
+		xas->xa_index--;
+	if (xas_not_node(xas->xa_node))
+		return xas_load(xas);
+
+	if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
+		xas->xa_offset--;
+
+	while (xas->xa_offset == 255) {
+		xas->xa_offset = xas->xa_node->offset - 1;
+		xas->xa_node = xa_parent(xas->xa, xas->xa_node);
+		if (!xas->xa_node)
+			return set_bounds(xas);
+	}
+
+	for (;;) {
+		entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
+		if (!xa_is_node(entry))
+			return entry;
+
+		xas->xa_node = xa_to_node(entry);
+		xas_set_offset(xas);
+	}
+}
+EXPORT_SYMBOL_GPL(__xas_prev);
+
+/*
+ * __xas_next() - Find the next entry in the XArray.
+ * @xas: XArray operation state.
+ *
+ * Helper function for xas_next() which handles all the complex cases
+ * out of line.
+ */
+void *__xas_next(struct xa_state *xas)
+{
+	void *entry;
+
+	if (!xas_frozen(xas->xa_node))
+		xas->xa_index++;
+	if (xas_not_node(xas->xa_node))
+		return xas_load(xas);
+
+	if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
+		xas->xa_offset++;
+
+	while (xas->xa_offset == XA_CHUNK_SIZE) {
+		xas->xa_offset = xas->xa_node->offset + 1;
+		xas->xa_node = xa_parent(xas->xa, xas->xa_node);
+		if (!xas->xa_node)
+			return set_bounds(xas);
+	}
+
+	for (;;) {
+		entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
+		if (!xa_is_node(entry))
+			return entry;
+
+		xas->xa_node = xa_to_node(entry);
+		xas_set_offset(xas);
+	}
+}
+EXPORT_SYMBOL_GPL(__xas_next);
+
 /**
  * xas_find() - Find the next present entry in the XArray.
  * @xas: XArray operation state.
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 17/74] xarray: Add xas_for_each_conflict
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (15 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 16/74] xarray: Step through " Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 18/74] xarray: Add xas_create_range Matthew Wilcox
                   ` (57 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

This iterator iterates over each entry that is stored in the index or
indices specified by the xa_state.  This is intended for use for a
conditional store of a multiindex entry, or to allow entries which are
about to be removed from the xarray to be disposed of properly.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/xarray.h | 17 ++++++++++++
 lib/test_xarray.c      | 63 ++++++++++++++++++++++++++++++++++++++++++
 lib/xarray.c           | 61 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 141 insertions(+)

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 921d41034d7d..0a9f66266c9a 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -769,6 +769,7 @@ static inline bool xas_retry(struct xa_state *xas, const void *entry)
 void *xas_load(struct xa_state *);
 void *xas_store(struct xa_state *, void *entry);
 void *xas_find(struct xa_state *, unsigned long max);
+void *xas_next_conflict(struct xa_state *);
 
 bool xas_get_tag(const struct xa_state *, xa_tag_t);
 void xas_set_tag(const struct xa_state *, xa_tag_t);
@@ -983,6 +984,22 @@ enum {
 	for (entry = xas_find_tagged(xas, max, tag); entry; \
 	     entry = xas_next_tagged(xas, max, tag))
 
+/**
+ * xas_for_each_conflict() - Iterate over a range of an XArray.
+ * @xas: XArray operation state.
+ * @entry: Entry retrieved from the array.
+ *
+ * The loop body will be executed for each entry in the XArray that lies
+ * within the range specified by @xas.  If the loop completes successfully,
+ * any entries that lie in this range will be replaced by @entry.  The caller
+ * may break out of the loop; if they do so, the contents of the XArray will
+ * be unchanged.  The operation may fail due to an out of memory condition.
+ * The caller may also call xa_set_err() to exit the loop while setting an
+ * error to record the reason.
+ */
+#define xas_for_each_conflict(xas, entry) \
+	while ((entry = xas_next_conflict(xas)))
+
 void *__xas_next(struct xa_state *);
 void *__xas_prev(struct xa_state *);
 
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index e74ade12c663..818cfd8746ba 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -315,6 +315,68 @@ static void check_multi_store(struct xarray *xa)
 	}
 }
 
+static void __check_store_iter(struct xarray *xa, unsigned long start,
+			unsigned int order, unsigned int present)
+{
+	XA_STATE_ORDER(xas, xa, start, order);
+	void *entry;
+	unsigned int count = 0;
+
+retry:
+	xas_for_each_conflict(&xas, entry) {
+		XA_BUG_ON(xa, !xa_is_value(entry));
+		XA_BUG_ON(xa, entry < xa_mk_value(start));
+		XA_BUG_ON(xa, entry > xa_mk_value(start + (1UL << order) - 1));
+		count++;
+	}
+	xas_store(&xas, xa_mk_value(start));
+	if (xas_nomem(&xas, GFP_KERNEL)) {
+		count = 0;
+		goto retry;
+	}
+	XA_BUG_ON(xa, xas_error(&xas));
+	XA_BUG_ON(xa, count != present);
+	XA_BUG_ON(xa, xa_load(xa, start) != xa_mk_value(start));
+	XA_BUG_ON(xa, xa_load(xa, start + (1UL << order) - 1) !=
+			xa_mk_value(start));
+	xa_erase_value(xa, start);
+}
+
+static void check_store_iter(struct xarray *xa)
+{
+	unsigned int i, j;
+
+	for (i = 0; i < 20; i++) {
+		unsigned int min = 1 << i;
+		unsigned int max = (2 << i) - 1;
+		__check_store_iter(xa, 0, i, 0);
+		XA_BUG_ON(xa, !xa_empty(xa));
+		__check_store_iter(xa, min, i, 0);
+		XA_BUG_ON(xa, !xa_empty(xa));
+
+		xa_store_value(xa, min, GFP_KERNEL);
+		__check_store_iter(xa, min, i, 1);
+		XA_BUG_ON(xa, !xa_empty(xa));
+		xa_store_value(xa, max, GFP_KERNEL);
+		__check_store_iter(xa, min, i, 1);
+		XA_BUG_ON(xa, !xa_empty(xa));
+
+		for (j = 0; j < min; j++)
+			xa_store_value(xa, j, GFP_KERNEL);
+		__check_store_iter(xa, 0, i, min);
+		XA_BUG_ON(xa, !xa_empty(xa));
+		for (j = 0; j < min; j++)
+			xa_store_value(xa, min + j, GFP_KERNEL);
+		__check_store_iter(xa, min, i, min);
+		XA_BUG_ON(xa, !xa_empty(xa));
+	}
+	xa_store_value(xa, 63, GFP_KERNEL);
+	xa_store_value(xa, 65, GFP_KERNEL);
+	__check_store_iter(xa, 64, 2, 1);
+	xa_erase_value(xa, 63);
+	XA_BUG_ON(xa, !xa_empty(xa));
+}
+
 static void check_multi_find(struct xarray *xa)
 {
 	unsigned long index;
@@ -506,6 +568,7 @@ static int xarray_checks(void)
 	check_multi_store(&array);
 	check_find(&array);
 	check_move(&array);
+	check_store_iter(&array);
 
 	printk("XArray: %u of %u tests passed\n", tests_passed, tests_run);
 	return (tests_run != tests_passed) ? 0 : -EINVAL;
diff --git a/lib/xarray.c b/lib/xarray.c
index ab1b6786711e..31c5332c8146 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1086,6 +1086,67 @@ void *xas_find_tagged(struct xa_state *xas, unsigned long max, xa_tag_t tag)
 }
 EXPORT_SYMBOL_GPL(xas_find_tagged);
 
+/**
+ * xas_next_conflict() - Step for xas_for_each_conflict().
+ * @xas: XArray operation state.
+ *
+ * This function does the work for xas_for_each_conflict().
+ *
+ * Context: Any context.  Expects xa_lock to be held.
+ * Return: The next entry in the range covered by @xas or %NULL.
+ */
+void *xas_next_conflict(struct xa_state *xas)
+{
+	void *curr;
+
+	if (xas_error(xas))
+		return NULL;
+
+	if (!xas->xa_node)
+		return NULL;
+
+	if (xas_top(xas->xa_node)) {
+		curr = xas_start(xas);
+		if (!curr)
+			return NULL;
+		while (xa_is_node(curr)) {
+			struct xa_node *node = xa_to_node(curr);
+			curr = xas_descend(xas, node);
+		}
+		if (curr)
+			return curr;
+	}
+
+	if (xas->xa_node->shift > xas->xa_shift)
+		return NULL;
+
+	for (;;) {
+		if (xas->xa_node->shift == xas->xa_shift) {
+			if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs)
+				break;
+		} else if (xas->xa_offset == XA_CHUNK_MASK) {
+			xas->xa_offset = xas->xa_node->offset;
+			xas->xa_node = xas->xa_node->parent;
+			if (!xas->xa_node)
+				break;
+			continue;
+		}
+		curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset);
+		if (xa_is_sibling(curr))
+			continue;
+		while (xa_is_node(curr)) {
+			xas->xa_node = xa_to_node(curr);
+			xas->xa_offset = 0;
+			curr = xa_entry_locked(xas->xa, xas->xa_node, 0);
+		}
+		if (curr)
+			return curr;
+	}
+	xas->xa_offset -= xas->xa_sibs;
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(xas_next_conflict);
+
 /**
  * xa_init_flags() - Initialise an empty XArray with flags.
  * @xa: XArray.
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 18/74] xarray: Add xas_create_range
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (16 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 17/74] xarray: Add xas_for_each_conflict Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 19/74] xarray: Add MAINTAINERS entry Matthew Wilcox
                   ` (56 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

This hopefully temporary function is useful for users who have not yet
been converted to multi-index entries.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/xarray.h |  2 ++
 lib/xarray.c           | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 0a9f66266c9a..b78c2e9aa065 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -780,6 +780,8 @@ void xas_init_tags(const struct xa_state *);
 bool xas_nomem(struct xa_state *, gfp_t);
 void xas_pause(struct xa_state *);
 
+void xas_create_range(struct xa_state *, unsigned long max);
+
 /**
  * xas_reload() - Refetch an entry from the xarray.
  * @xas: XArray operation state.
diff --git a/lib/xarray.c b/lib/xarray.c
index 31c5332c8146..8dddad5b237c 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -624,6 +624,28 @@ static void *xas_create(struct xa_state *xas)
 	return entry;
 }
 
+/**
+ * xas_create_range() - Ensure that stores to this range will succeed
+ * @xas: XArray operation state.
+ * @max: The highest index to create a slot for.
+ *
+ * Creates all of the slots in the range between the current position of
+ * @xas and @max.  This is for the benefit of users who have not yet been
+ * converted to multi-index entries.
+ *
+ * The implementation is naive.
+ */
+void xas_create_range(struct xa_state *xas, unsigned long max)
+{
+	XA_STATE(tmp, xas->xa, xas->xa_index);
+
+	do {
+		xas_create(&tmp);
+		xas_set(&tmp, tmp.xa_index + XA_CHUNK_SIZE);
+	} while (tmp.xa_index < max);
+}
+EXPORT_SYMBOL_GPL(xas_create_range);
+
 static void update_node(struct xa_state *xas, struct xa_node *node,
 		int count, int values)
 {
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 19/74] xarray: Add MAINTAINERS entry
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (17 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 18/74] xarray: Add xas_create_range Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 20/74] page cache: Rearrange address_space Matthew Wilcox
                   ` (55 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Add myself as XArray and IDR maintainer.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 MAINTAINERS | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 6dc2c9cb2d7b..959cc42e33ad 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15596,6 +15596,17 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/vdso
 S:	Maintained
 F:	arch/x86/entry/vdso/
 
+XARRAY
+M:	Matthew Wilcox <willy@infradead.org>
+L:	linux-fsdevel@vger.kernel.org
+S:	Supported
+F:	Documentation/core-api/xarray.rst
+F:	lib/idr.c
+F:	lib/xarray.c
+F:	include/linux/idr.h
+F:	include/linux/xarray.h
+F:	tools/testing/radix-tree
+
 XC2028/3028 TUNER DRIVER
 M:	Mauro Carvalho Chehab <mchehab@kernel.org>
 L:	linux-media@vger.kernel.org
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 20/74] page cache: Rearrange address_space
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (18 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 19/74] xarray: Add MAINTAINERS entry Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  1:59 ` [PATCH v14 21/74] page cache: Convert hole search to XArray Matthew Wilcox
                   ` (54 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Change i_pages from a radix_tree_root to an xarray, convert the
documentation into kernel-doc format and change the order of the elements
to pack them better on 64-bit systems.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/fs.h | 46 +++++++++++++++++++++++++++++++---------------
 1 file changed, 31 insertions(+), 15 deletions(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 8c1c56584e08..f1716ce5ff6f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -396,24 +396,40 @@ int pagecache_write_end(struct file *, struct address_space *mapping,
 				loff_t pos, unsigned len, unsigned copied,
 				struct page *page, void *fsdata);
 
+/**
+ * struct address_space - Contents of a cacheable, mappable object.
+ * @host: Owner, either the inode or the block_device.
+ * @i_pages: Cached pages.
+ * @gfp_mask: Memory allocation flags to use for allocating pages.
+ * @i_mmap_writable: Number of VM_SHARED mappings.
+ * @i_mmap: Tree of private and shared mappings.
+ * @i_mmap_rwsem: Protects @i_mmap and @i_mmap_writable.
+ * @nrpages: Number of page entries, protected by the i_pages lock.
+ * @nrexceptional: Shadow or DAX entries, protected by the i_pages lock.
+ * @writeback_index: Writeback starts here.
+ * @a_ops: Methods.
+ * @flags: Error bits and flags (AS_*).
+ * @wb_err: The most recent error which has occurred.
+ * @private_lock: For use by the owner of the address_space.
+ * @private_list: For use by the owner of the address_space.
+ * @private_data: For use by the owner of the address_space.
+ */
 struct address_space {
-	struct inode		*host;		/* owner: inode, block_device */
-	struct radix_tree_root	i_pages;	/* cached pages */
-	atomic_t		i_mmap_writable;/* count VM_SHARED mappings */
-	struct rb_root_cached	i_mmap;		/* tree of private and shared mappings */
-	struct rw_semaphore	i_mmap_rwsem;	/* protect tree, count, list */
-	/* Protected by the i_pages lock */
-	unsigned long		nrpages;	/* number of total pages */
-	/* number of shadow or DAX exceptional entries */
+	struct inode		*host;
+	struct xarray		i_pages;
+	gfp_t			gfp_mask;
+	atomic_t		i_mmap_writable;
+	struct rb_root_cached	i_mmap;
+	struct rw_semaphore	i_mmap_rwsem;
+	unsigned long		nrpages;
 	unsigned long		nrexceptional;
-	pgoff_t			writeback_index;/* writeback starts here */
-	const struct address_space_operations *a_ops;	/* methods */
-	unsigned long		flags;		/* error bits */
-	spinlock_t		private_lock;	/* for use by the address_space */
-	gfp_t			gfp_mask;	/* implicit gfp mask for allocations */
-	struct list_head	private_list;	/* for use by the address_space */
-	void			*private_data;	/* ditto */
+	pgoff_t			writeback_index;
+	const struct address_space_operations *a_ops;
+	unsigned long		flags;
 	errseq_t		wb_err;
+	spinlock_t		private_lock;
+	struct list_head	private_list;
+	void			*private_data;
 } __attribute__((aligned(sizeof(long)))) __randomize_layout;
 	/*
 	 * On most architectures that alignment is already the case; but
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 21/74] page cache: Convert hole search to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (19 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 20/74] page cache: Rearrange address_space Matthew Wilcox
@ 2018-06-17  1:59 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 22/74] page cache: Add and replace pages using the XArray Matthew Wilcox
                   ` (53 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  1:59 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

The page cache offers the ability to search for a miss in the previous or
next N locations.  Rather than teach the XArray about the page cache's
definition of a miss, use xas_prev() and xas_next() to search the page
array.  This should be more efficient as it does not have to start the
lookup from the top for each index.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 fs/nfs/blocklayout/blocklayout.c |   2 +-
 include/linux/pagemap.h          |   4 +-
 mm/filemap.c                     | 110 ++++++++++++++-----------------
 mm/readahead.c                   |   4 +-
 4 files changed, 55 insertions(+), 65 deletions(-)

diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
index 7cb5c38c19e4..961901685007 100644
--- a/fs/nfs/blocklayout/blocklayout.c
+++ b/fs/nfs/blocklayout/blocklayout.c
@@ -895,7 +895,7 @@ static u64 pnfs_num_cont_bytes(struct inode *inode, pgoff_t idx)
 	end = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
 	if (end != inode->i_mapping->nrpages) {
 		rcu_read_lock();
-		end = page_cache_next_hole(mapping, idx + 1, ULONG_MAX);
+		end = page_cache_next_gap(mapping, idx + 1, ULONG_MAX);
 		rcu_read_unlock();
 	}
 
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index b1bd2186e6d2..2f5d2d3ebaac 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -241,9 +241,9 @@ static inline gfp_t readahead_gfp_mask(struct address_space *x)
 
 typedef int filler_t(void *, struct page *);
 
-pgoff_t page_cache_next_hole(struct address_space *mapping,
+pgoff_t page_cache_next_gap(struct address_space *mapping,
 			     pgoff_t index, unsigned long max_scan);
-pgoff_t page_cache_prev_hole(struct address_space *mapping,
+pgoff_t page_cache_prev_gap(struct address_space *mapping,
 			     pgoff_t index, unsigned long max_scan);
 
 #define FGP_ACCESSED		0x00000001
diff --git a/mm/filemap.c b/mm/filemap.c
index 4de14e75c4ec..8de36e14e22f 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1326,86 +1326,76 @@ int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
 }
 
 /**
- * page_cache_next_hole - find the next hole (not-present entry)
- * @mapping: mapping
- * @index: index
- * @max_scan: maximum range to search
- *
- * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the
- * lowest indexed hole.
- *
- * Returns: the index of the hole if found, otherwise returns an index
- * outside of the set specified (in which case 'return - index >=
- * max_scan' will be true). In rare cases of index wrap-around, 0 will
- * be returned.
- *
- * page_cache_next_hole may be called under rcu_read_lock. However,
- * like radix_tree_gang_lookup, this will not atomically search a
- * snapshot of the tree at a single point in time. For example, if a
- * hole is created at index 5, then subsequently a hole is created at
- * index 10, page_cache_next_hole covering both indexes may return 10
- * if called under rcu_read_lock.
+ * page_cache_next_gap() - Find the next gap in the page cache.
+ * @mapping: Mapping.
+ * @index: Index.
+ * @max_scan: Maximum range to search.
+ *
+ * Search the range [index, min(index + max_scan - 1, ULONG_MAX)] for the
+ * gap with the lowest index.
+ *
+ * This function may be called under the rcu_read_lock.  However, this will
+ * not atomically search a snapshot of the cache at a single point in time.
+ * For example, if a gap is created at index 5, then subsequently a gap is
+ * created at index 10, page_cache_next_gap covering both indices may
+ * return 10 if called under the rcu_read_lock.
+ *
+ * Return: The index of the gap if found, otherwise an index outside the
+ * range specified (in which case 'return - index >= max_scan' will be true).
+ * In the rare case of index wrap-around, 0 will be returned.
  */
-pgoff_t page_cache_next_hole(struct address_space *mapping,
+pgoff_t page_cache_next_gap(struct address_space *mapping,
 			     pgoff_t index, unsigned long max_scan)
 {
-	unsigned long i;
+	XA_STATE(xas, &mapping->i_pages, index);
 
-	for (i = 0; i < max_scan; i++) {
-		struct page *page;
-
-		page = radix_tree_lookup(&mapping->i_pages, index);
-		if (!page || xa_is_value(page))
+	while (max_scan--) {
+		void *entry = xas_next(&xas);
+		if (!entry || xa_is_value(entry))
 			break;
-		index++;
-		if (index == 0)
+		if (xas.xa_index == 0)
 			break;
 	}
 
-	return index;
+	return xas.xa_index;
 }
-EXPORT_SYMBOL(page_cache_next_hole);
+EXPORT_SYMBOL(page_cache_next_gap);
 
 /**
- * page_cache_prev_hole - find the prev hole (not-present entry)
- * @mapping: mapping
- * @index: index
- * @max_scan: maximum range to search
- *
- * Search backwards in the range [max(index-max_scan+1, 0), index] for
- * the first hole.
- *
- * Returns: the index of the hole if found, otherwise returns an index
- * outside of the set specified (in which case 'index - return >=
- * max_scan' will be true). In rare cases of wrap-around, ULONG_MAX
- * will be returned.
- *
- * page_cache_prev_hole may be called under rcu_read_lock. However,
- * like radix_tree_gang_lookup, this will not atomically search a
- * snapshot of the tree at a single point in time. For example, if a
- * hole is created at index 10, then subsequently a hole is created at
- * index 5, page_cache_prev_hole covering both indexes may return 5 if
- * called under rcu_read_lock.
+ * page_cache_prev_gap() - Find the next gap in the page cache.
+ * @mapping: Mapping.
+ * @index: Index.
+ * @max_scan: Maximum range to search.
+ *
+ * Search the range [max(index - max_scan + 1, 0), index] for the
+ * gap with the highest index.
+ *
+ * This function may be called under the rcu_read_lock.  However, this will
+ * not atomically search a snapshot of the cache at a single point in time.
+ * For example, if a gap is created at index 10, then subsequently a gap is
+ * created at index 5, page_cache_prev_gap() covering both indices may
+ * return 5 if called under the rcu_read_lock.
+ *
+ * Return: The index of the gap if found, otherwise an index outside the
+ * range specified (in which case 'index - return >= max_scan' will be true).
+ * In the rare case of wrap-around, ULONG_MAX will be returned.
  */
-pgoff_t page_cache_prev_hole(struct address_space *mapping,
+pgoff_t page_cache_prev_gap(struct address_space *mapping,
 			     pgoff_t index, unsigned long max_scan)
 {
-	unsigned long i;
-
-	for (i = 0; i < max_scan; i++) {
-		struct page *page;
+	XA_STATE(xas, &mapping->i_pages, index);
 
-		page = radix_tree_lookup(&mapping->i_pages, index);
-		if (!page || xa_is_value(page))
+	while (max_scan--) {
+		void *entry = xas_prev(&xas);
+		if (!entry || xa_is_value(entry))
 			break;
-		index--;
-		if (index == ULONG_MAX)
+		if (xas.xa_index == ULONG_MAX)
 			break;
 	}
 
-	return index;
+	return xas.xa_index;
 }
-EXPORT_SYMBOL(page_cache_prev_hole);
+EXPORT_SYMBOL(page_cache_prev_gap);
 
 /**
  * find_get_entry - find and get a page cache entry
diff --git a/mm/readahead.c b/mm/readahead.c
index 3757aa549709..59998ca31f2a 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -334,7 +334,7 @@ static pgoff_t count_history_pages(struct address_space *mapping,
 	pgoff_t head;
 
 	rcu_read_lock();
-	head = page_cache_prev_hole(mapping, offset - 1, max);
+	head = page_cache_prev_gap(mapping, offset - 1, max);
 	rcu_read_unlock();
 
 	return offset - 1 - head;
@@ -422,7 +422,7 @@ ondemand_readahead(struct address_space *mapping,
 		pgoff_t start;
 
 		rcu_read_lock();
-		start = page_cache_next_hole(mapping, offset + 1, max_pages);
+		start = page_cache_next_gap(mapping, offset + 1, max_pages);
 		rcu_read_unlock();
 
 		if (!start || start - offset > max_pages)
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 22/74] page cache: Add and replace pages using the XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (20 preceding siblings ...)
  2018-06-17  1:59 ` [PATCH v14 21/74] page cache: Convert hole search to XArray Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 23/74] page cache: Convert page deletion to XArray Matthew Wilcox
                   ` (52 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Use the XArray APIs to add and replace pages in the page cache.  This
removes two uses of the radix tree preload API and is significantly
shorter code.  It also removes the last user of __radix_tree_create()
outside radix-tree.c itself, so make it static.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/radix-tree.h |   3 -
 include/linux/swap.h       |   8 ++-
 lib/radix-tree.c           |   6 +-
 mm/filemap.c               | 139 +++++++++++++++----------------------
 4 files changed, 66 insertions(+), 90 deletions(-)

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index f64beb9ba175..4b6f685309fc 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -231,9 +231,6 @@ static inline int radix_tree_exception(void *arg)
 	return unlikely((unsigned long)arg & RADIX_TREE_ENTRY_MASK);
 }
 
-int __radix_tree_create(struct radix_tree_root *, unsigned long index,
-			unsigned order, struct radix_tree_node **nodep,
-			void __rcu ***slotp);
 int __radix_tree_insert(struct radix_tree_root *, unsigned long index,
 			unsigned order, void *);
 static inline int radix_tree_insert(struct radix_tree_root *root,
diff --git a/include/linux/swap.h b/include/linux/swap.h
index f73eafcaf4e9..1b91e7f7bdeb 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -300,8 +300,12 @@ void *workingset_eviction(struct address_space *mapping, struct page *page);
 bool workingset_refault(void *shadow);
 void workingset_activation(struct page *page);
 
-/* Do not use directly, use workingset_lookup_update */
-void workingset_update_node(struct radix_tree_node *node);
+/* Only track the nodes of mappings with shadow entries */
+void workingset_update_node(struct xa_node *node);
+#define mapping_set_update(xas, mapping) do {				\
+	if (!dax_mapping(mapping) && !shmem_mapping(mapping))		\
+		xas_set_update(xas, workingset_update_node);		\
+} while (0)
 
 /* Returns workingset_update_node() if the mapping has shadow entries. */
 #define workingset_lookup_update(mapping)				\
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index f7785f7cbd5f..5c8a262f506c 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -740,9 +740,9 @@ static bool delete_node(struct radix_tree_root *root,
  *
  *	Returns -ENOMEM, or 0 for success.
  */
-int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
-			unsigned order, struct radix_tree_node **nodep,
-			void __rcu ***slotp)
+static int __radix_tree_create(struct radix_tree_root *root,
+		unsigned long index, unsigned order,
+		struct radix_tree_node **nodep, void __rcu ***slotp)
 {
 	struct radix_tree_node *node = NULL, *child;
 	void __rcu **slot = (void __rcu **)&root->xa_head;
diff --git a/mm/filemap.c b/mm/filemap.c
index 8de36e14e22f..965ff68e5b8d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -111,35 +111,6 @@
  *   ->tasklist_lock            (memory_failure, collect_procs_ao)
  */
 
-static int page_cache_tree_insert(struct address_space *mapping,
-				  struct page *page, void **shadowp)
-{
-	struct radix_tree_node *node;
-	void **slot;
-	int error;
-
-	error = __radix_tree_create(&mapping->i_pages, page->index, 0,
-				    &node, &slot);
-	if (error)
-		return error;
-	if (*slot) {
-		void *p;
-
-		p = radix_tree_deref_slot_protected(slot,
-						    &mapping->i_pages.xa_lock);
-		if (!xa_is_value(p))
-			return -EEXIST;
-
-		mapping->nrexceptional--;
-		if (shadowp)
-			*shadowp = p;
-	}
-	__radix_tree_replace(&mapping->i_pages, node, slot, page,
-			     workingset_lookup_update(mapping));
-	mapping->nrpages++;
-	return 0;
-}
-
 static void page_cache_tree_delete(struct address_space *mapping,
 				   struct page *page, void *shadow)
 {
@@ -775,51 +746,44 @@ EXPORT_SYMBOL(file_write_and_wait_range);
  * locked.  This function does not add the new page to the LRU, the
  * caller must do that.
  *
- * The remove + add is atomic.  The only way this function can fail is
- * memory allocation failure.
+ * The remove + add is atomic.  This function cannot fail.
  */
 int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
 {
-	int error;
+	struct address_space *mapping = old->mapping;
+	void (*freepage)(struct page *) = mapping->a_ops->freepage;
+	pgoff_t offset = old->index;
+	XA_STATE(xas, &mapping->i_pages, offset);
+	unsigned long flags;
 
 	VM_BUG_ON_PAGE(!PageLocked(old), old);
 	VM_BUG_ON_PAGE(!PageLocked(new), new);
 	VM_BUG_ON_PAGE(new->mapping, new);
 
-	error = radix_tree_preload(gfp_mask & GFP_RECLAIM_MASK);
-	if (!error) {
-		struct address_space *mapping = old->mapping;
-		void (*freepage)(struct page *);
-		unsigned long flags;
-
-		pgoff_t offset = old->index;
-		freepage = mapping->a_ops->freepage;
+	get_page(new);
+	new->mapping = mapping;
+	new->index = offset;
 
-		get_page(new);
-		new->mapping = mapping;
-		new->index = offset;
+	xas_lock_irqsave(&xas, flags);
+	xas_store(&xas, new);
 
-		xa_lock_irqsave(&mapping->i_pages, flags);
-		__delete_from_page_cache(old, NULL);
-		error = page_cache_tree_insert(mapping, new, NULL);
-		BUG_ON(error);
-
-		/*
-		 * hugetlb pages do not participate in page cache accounting.
-		 */
-		if (!PageHuge(new))
-			__inc_node_page_state(new, NR_FILE_PAGES);
-		if (PageSwapBacked(new))
-			__inc_node_page_state(new, NR_SHMEM);
-		xa_unlock_irqrestore(&mapping->i_pages, flags);
-		mem_cgroup_migrate(old, new);
-		radix_tree_preload_end();
-		if (freepage)
-			freepage(old);
-		put_page(old);
-	}
+	old->mapping = NULL;
+	/* hugetlb pages do not participate in page cache accounting. */
+	if (!PageHuge(old))
+		__dec_node_page_state(new, NR_FILE_PAGES);
+	if (!PageHuge(new))
+		__inc_node_page_state(new, NR_FILE_PAGES);
+	if (PageSwapBacked(old))
+		__dec_node_page_state(new, NR_SHMEM);
+	if (PageSwapBacked(new))
+		__inc_node_page_state(new, NR_SHMEM);
+	xas_unlock_irqrestore(&xas, flags);
+	mem_cgroup_migrate(old, new);
+	if (freepage)
+		freepage(old);
+	put_page(old);
 
-	return error;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(replace_page_cache_page);
 
@@ -828,12 +792,15 @@ static int __add_to_page_cache_locked(struct page *page,
 				      pgoff_t offset, gfp_t gfp_mask,
 				      void **shadowp)
 {
+	XA_STATE(xas, &mapping->i_pages, offset);
 	int huge = PageHuge(page);
 	struct mem_cgroup *memcg;
 	int error;
+	void *old;
 
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	VM_BUG_ON_PAGE(PageSwapBacked(page), page);
+	mapping_set_update(&xas, mapping);
 
 	if (!huge) {
 		error = mem_cgroup_try_charge(page, current->mm,
@@ -842,39 +809,47 @@ static int __add_to_page_cache_locked(struct page *page,
 			return error;
 	}
 
-	error = radix_tree_maybe_preload(gfp_mask & GFP_RECLAIM_MASK);
-	if (error) {
-		if (!huge)
-			mem_cgroup_cancel_charge(page, memcg, false);
-		return error;
-	}
-
 	get_page(page);
 	page->mapping = mapping;
 	page->index = offset;
 
-	xa_lock_irq(&mapping->i_pages);
-	error = page_cache_tree_insert(mapping, page, shadowp);
-	radix_tree_preload_end();
-	if (unlikely(error))
-		goto err_insert;
+	do {
+		xas_lock_irq(&xas);
+		old = xas_load(&xas);
+		if (old && !xa_is_value(old))
+			xas_set_err(&xas, -EEXIST);
+		xas_store(&xas, page);
+		if (xas_error(&xas))
+			goto unlock;
+
+		if (xa_is_value(old)) {
+			mapping->nrexceptional--;
+			if (shadowp)
+				*shadowp = old;
+		}
+		mapping->nrpages++;
+
+		/* hugetlb pages do not participate in page cache accounting */
+		if (!huge)
+			__inc_node_page_state(page, NR_FILE_PAGES);
+unlock:
+		xas_unlock_irq(&xas);
+	} while (xas_nomem(&xas, gfp_mask & GFP_RECLAIM_MASK));
+
+	if (xas_error(&xas))
+		goto error;
 
-	/* hugetlb pages do not participate in page cache accounting. */
-	if (!huge)
-		__inc_node_page_state(page, NR_FILE_PAGES);
-	xa_unlock_irq(&mapping->i_pages);
 	if (!huge)
 		mem_cgroup_commit_charge(page, memcg, false, false);
 	trace_mm_filemap_add_to_page_cache(page);
 	return 0;
-err_insert:
+error:
 	page->mapping = NULL;
 	/* Leave page->index set: truncation relies upon it */
-	xa_unlock_irq(&mapping->i_pages);
 	if (!huge)
 		mem_cgroup_cancel_charge(page, memcg, false);
 	put_page(page);
-	return error;
+	return xas_error(&xas);
 }
 
 /**
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 23/74] page cache: Convert page deletion to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (21 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 22/74] page cache: Add and replace pages using the XArray Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 24/74] page cache: Convert find_get_entry " Matthew Wilcox
                   ` (51 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

The code is slightly shorter and simpler.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/filemap.c | 31 +++++++++++++------------------
 1 file changed, 13 insertions(+), 18 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 965ff68e5b8d..7cdb1d4b8117 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -111,31 +111,26 @@
  *   ->tasklist_lock            (memory_failure, collect_procs_ao)
  */
 
-static void page_cache_tree_delete(struct address_space *mapping,
+static void page_cache_delete(struct address_space *mapping,
 				   struct page *page, void *shadow)
 {
-	int i, nr;
+	XA_STATE(xas, &mapping->i_pages, page->index);
+	unsigned int nr = 1;
 
-	/* hugetlb pages are represented by one entry in the radix tree */
-	nr = PageHuge(page) ? 1 : hpage_nr_pages(page);
+	mapping_set_update(&xas, mapping);
+
+	/* hugetlb pages are represented by a single entry in the xarray */
+	if (!PageHuge(page)) {
+		xas_set_order(&xas, page->index, compound_order(page));
+		nr = 1U << compound_order(page);
+	}
 
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	VM_BUG_ON_PAGE(PageTail(page), page);
 	VM_BUG_ON_PAGE(nr != 1 && shadow, page);
 
-	for (i = 0; i < nr; i++) {
-		struct radix_tree_node *node;
-		void **slot;
-
-		__radix_tree_lookup(&mapping->i_pages, page->index + i,
-				    &node, &slot);
-
-		VM_BUG_ON_PAGE(!node && nr != 1, page);
-
-		radix_tree_clear_tags(&mapping->i_pages, node, slot);
-		__radix_tree_replace(&mapping->i_pages, node, slot, shadow,
-				workingset_lookup_update(mapping));
-	}
+	xas_store(&xas, shadow);
+	xas_init_tags(&xas);
 
 	page->mapping = NULL;
 	/* Leave page->index set: truncation lookup relies upon it */
@@ -234,7 +229,7 @@ void __delete_from_page_cache(struct page *page, void *shadow)
 	trace_mm_filemap_delete_from_page_cache(page);
 
 	unaccount_page_cache_page(mapping, page);
-	page_cache_tree_delete(mapping, page, shadow);
+	page_cache_delete(mapping, page, shadow);
 }
 
 static void page_cache_free_page(struct address_space *mapping,
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 24/74] page cache: Convert find_get_entry to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (22 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 23/74] page cache: Convert page deletion to XArray Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 25/74] page cache: Convert find_get_entries " Matthew Wilcox
                   ` (50 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Slightly shorter and simpler code.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/filemap.c | 63 +++++++++++++++++++++++-----------------------------
 1 file changed, 28 insertions(+), 35 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 7cdb1d4b8117..6db3d35ff5f6 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1382,47 +1382,40 @@ EXPORT_SYMBOL(page_cache_prev_gap);
  */
 struct page *find_get_entry(struct address_space *mapping, pgoff_t offset)
 {
-	void **pagep;
+	XA_STATE(xas, &mapping->i_pages, offset);
 	struct page *head, *page;
 
 	rcu_read_lock();
 repeat:
-	page = NULL;
-	pagep = radix_tree_lookup_slot(&mapping->i_pages, offset);
-	if (pagep) {
-		page = radix_tree_deref_slot(pagep);
-		if (unlikely(!page))
-			goto out;
-		if (radix_tree_exception(page)) {
-			if (radix_tree_deref_retry(page))
-				goto repeat;
-			/*
-			 * A shadow entry of a recently evicted page,
-			 * or a swap entry from shmem/tmpfs.  Return
-			 * it without attempting to raise page count.
-			 */
-			goto out;
-		}
+	xas_reset(&xas);
+	page = xas_load(&xas);
+	if (xas_retry(&xas, page))
+		goto repeat;
+	/*
+	 * A shadow entry of a recently evicted page, or a swap entry from
+	 * shmem/tmpfs.  Return it without attempting to raise page count.
+	 */
+	if (!page || xa_is_value(page))
+		goto out;
 
-		head = compound_head(page);
-		if (!page_cache_get_speculative(head))
-			goto repeat;
+	head = compound_head(page);
+	if (!page_cache_get_speculative(head))
+		goto repeat;
 
-		/* The page was split under us? */
-		if (compound_head(page) != head) {
-			put_page(head);
-			goto repeat;
-		}
+	/* The page was split under us? */
+	if (compound_head(page) != head) {
+		put_page(head);
+		goto repeat;
+	}
 
-		/*
-		 * Has the page moved?
-		 * This is part of the lockless pagecache protocol. See
-		 * include/linux/pagemap.h for details.
-		 */
-		if (unlikely(page != *pagep)) {
-			put_page(head);
-			goto repeat;
-		}
+	/*
+	 * Has the page moved?
+	 * This is part of the lockless pagecache protocol. See
+	 * include/linux/pagemap.h for details.
+	 */
+	if (unlikely(page != xas_reload(&xas))) {
+		put_page(head);
+		goto repeat;
 	}
 out:
 	rcu_read_unlock();
@@ -1453,7 +1446,7 @@ struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset)
 
 repeat:
 	page = find_get_entry(mapping, offset);
-	if (page && !radix_tree_exception(page)) {
+	if (page && !xa_is_value(page)) {
 		lock_page(page);
 		/* Has the page been truncated? */
 		if (unlikely(page_mapping(page) != mapping)) {
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 25/74] page cache: Convert find_get_entries to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (23 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 24/74] page cache: Convert find_get_entry " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 26/74] page cache: Convert find_get_pages_range " Matthew Wilcox
                   ` (49 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Slightly shorter and simpler code.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/filemap.c | 51 +++++++++++++++++++++++----------------------------
 1 file changed, 23 insertions(+), 28 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 6db3d35ff5f6..b49290131e85 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1578,53 +1578,48 @@ unsigned find_get_entries(struct address_space *mapping,
 			  pgoff_t start, unsigned int nr_entries,
 			  struct page **entries, pgoff_t *indices)
 {
-	void **slot;
+	XA_STATE(xas, &mapping->i_pages, start);
+	struct page *page;
 	unsigned int ret = 0;
-	struct radix_tree_iter iter;
 
 	if (!nr_entries)
 		return 0;
 
 	rcu_read_lock();
-	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
-		struct page *head, *page;
-repeat:
-		page = radix_tree_deref_slot(slot);
-		if (unlikely(!page))
+	xas_for_each(&xas, page, ULONG_MAX) {
+		struct page *head;
+		if (xas_retry(&xas, page))
 			continue;
-		if (radix_tree_exception(page)) {
-			if (radix_tree_deref_retry(page)) {
-				slot = radix_tree_iter_retry(&iter);
-				continue;
-			}
-			/*
-			 * A shadow entry of a recently evicted page, a swap
-			 * entry from shmem/tmpfs or a DAX entry.  Return it
-			 * without attempting to raise page count.
-			 */
+		/*
+		 * A shadow entry of a recently evicted page, a swap
+		 * entry from shmem/tmpfs or a DAX entry.  Return it
+		 * without attempting to raise page count.
+		 */
+		if (xa_is_value(page))
 			goto export;
-		}
 
 		head = compound_head(page);
 		if (!page_cache_get_speculative(head))
-			goto repeat;
+			goto retry;
 
 		/* The page was split under us? */
-		if (compound_head(page) != head) {
-			put_page(head);
-			goto repeat;
-		}
+		if (compound_head(page) != head)
+			goto put_page;
 
 		/* Has the page moved? */
-		if (unlikely(page != *slot)) {
-			put_page(head);
-			goto repeat;
-		}
+		if (unlikely(page != xas_reload(&xas)))
+			goto put_page;
+
 export:
-		indices[ret] = iter.index;
+		indices[ret] = xas.xa_index;
 		entries[ret] = page;
 		if (++ret == nr_entries)
 			break;
+		continue;
+put_page:
+		put_page(head);
+retry:
+		xas_reset(&xas);
 	}
 	rcu_read_unlock();
 	return ret;
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 26/74] page cache: Convert find_get_pages_range to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (24 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 25/74] page cache: Convert find_get_entries " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 27/74] page cache: Convert find_get_pages_contig " Matthew Wilcox
                   ` (48 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

The 'end' parameter of the xas_for_each iterator avoids a useless
iteration at the end of the range.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/filemap.c | 52 +++++++++++++++++++---------------------------------
 1 file changed, 19 insertions(+), 33 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index b49290131e85..019c263bb6be 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1650,64 +1650,50 @@ unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
 			      pgoff_t end, unsigned int nr_pages,
 			      struct page **pages)
 {
-	struct radix_tree_iter iter;
-	void **slot;
+	XA_STATE(xas, &mapping->i_pages, *start);
+	struct page *page;
 	unsigned ret = 0;
 
 	if (unlikely(!nr_pages))
 		return 0;
 
 	rcu_read_lock();
-	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, *start) {
-		struct page *head, *page;
-
-		if (iter.index > end)
-			break;
-repeat:
-		page = radix_tree_deref_slot(slot);
-		if (unlikely(!page))
+	xas_for_each(&xas, page, end) {
+		struct page *head;
+		if (xas_retry(&xas, page))
 			continue;
-
-		if (radix_tree_exception(page)) {
-			if (radix_tree_deref_retry(page)) {
-				slot = radix_tree_iter_retry(&iter);
-				continue;
-			}
-			/*
-			 * A shadow entry of a recently evicted page,
-			 * or a swap entry from shmem/tmpfs.  Skip
-			 * over it.
-			 */
+		/* Skip over shadow, swap and DAX entries */
+		if (xa_is_value(page))
 			continue;
-		}
 
 		head = compound_head(page);
 		if (!page_cache_get_speculative(head))
-			goto repeat;
+			goto retry;
 
 		/* The page was split under us? */
-		if (compound_head(page) != head) {
-			put_page(head);
-			goto repeat;
-		}
+		if (compound_head(page) != head)
+			goto put_page;
 
 		/* Has the page moved? */
-		if (unlikely(page != *slot)) {
-			put_page(head);
-			goto repeat;
-		}
+		if (unlikely(page != xas_reload(&xas)))
+			goto put_page;
 
 		pages[ret] = page;
 		if (++ret == nr_pages) {
-			*start = pages[ret - 1]->index + 1;
+			*start = page->index + 1;
 			goto out;
 		}
+		continue;
+put_page:
+		put_page(head);
+retry:
+		xas_reset(&xas);
 	}
 
 	/*
 	 * We come here when there is no page beyond @end. We take care to not
 	 * overflow the index @start as it confuses some of the callers. This
-	 * breaks the iteration when there is page at index -1 but that is
+	 * breaks the iteration when there is a page at index -1 but that is
 	 * already broken anyway.
 	 */
 	if (end == (pgoff_t)-1)
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 27/74] page cache: Convert find_get_pages_contig to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (25 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 26/74] page cache: Convert find_get_pages_range " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 28/74] page cache; Convert find_get_pages_range_tag " Matthew Wilcox
                   ` (47 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

There's no direct replacement for radix_tree_for_each_contig()
in the XArray API as it's an unusual thing to do.  Instead,
open-code a loop using xas_next().  This removes the only user of
radix_tree_for_each_contig() so delete the iterator from the API and
the test suite code for it.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 .clang-format                          |  1 -
 include/linux/radix-tree.h             | 17 ---------
 mm/filemap.c                           | 53 +++++++++++---------------
 tools/testing/radix-tree/regression3.c | 23 -----------
 4 files changed, 22 insertions(+), 72 deletions(-)

diff --git a/.clang-format b/.clang-format
index faffc0d5af4e..c1de31c6875e 100644
--- a/.clang-format
+++ b/.clang-format
@@ -323,7 +323,6 @@ ForEachMacros:
   - 'protocol_for_each_card'
   - 'protocol_for_each_dev'
   - 'queue_for_each_hw_ctx'
-  - 'radix_tree_for_each_contig'
   - 'radix_tree_for_each_slot'
   - 'radix_tree_for_each_tagged'
   - 'rbtree_postorder_for_each_entry_safe'
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 4b6f685309fc..eefa0b099dd5 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -522,23 +522,6 @@ static __always_inline void __rcu **radix_tree_next_slot(void __rcu **slot,
 	     slot || (slot = radix_tree_next_chunk(root, iter, 0)) ;	\
 	     slot = radix_tree_next_slot(slot, iter, 0))
 
-/**
- * radix_tree_for_each_contig - iterate over contiguous slots
- *
- * @slot:	the void** variable for pointer to slot
- * @root:	the struct radix_tree_root pointer
- * @iter:	the struct radix_tree_iter pointer
- * @start:	iteration starting index
- *
- * @slot points to radix tree slot, @iter->index contains its index.
- */
-#define radix_tree_for_each_contig(slot, root, iter, start)		\
-	for (slot = radix_tree_iter_init(iter, start) ;			\
-	     slot || (slot = radix_tree_next_chunk(root, iter,		\
-				RADIX_TREE_ITER_CONTIG)) ;		\
-	     slot = radix_tree_next_slot(slot, iter,			\
-				RADIX_TREE_ITER_CONTIG))
-
 /**
  * radix_tree_for_each_tagged - iterate over tagged slots
  *
diff --git a/mm/filemap.c b/mm/filemap.c
index 019c263bb6be..8a69613fcdf3 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1721,57 +1721,43 @@ unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
 unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
 			       unsigned int nr_pages, struct page **pages)
 {
-	struct radix_tree_iter iter;
-	void **slot;
+	XA_STATE(xas, &mapping->i_pages, index);
+	struct page *page;
 	unsigned int ret = 0;
 
 	if (unlikely(!nr_pages))
 		return 0;
 
 	rcu_read_lock();
-	radix_tree_for_each_contig(slot, &mapping->i_pages, &iter, index) {
-		struct page *head, *page;
-repeat:
-		page = radix_tree_deref_slot(slot);
-		/* The hole, there no reason to continue */
-		if (unlikely(!page))
-			break;
-
-		if (radix_tree_exception(page)) {
-			if (radix_tree_deref_retry(page)) {
-				slot = radix_tree_iter_retry(&iter);
-				continue;
-			}
-			/*
-			 * A shadow entry of a recently evicted page,
-			 * or a swap entry from shmem/tmpfs.  Stop
-			 * looking for contiguous pages.
-			 */
+	for (page = xas_load(&xas); page; page = xas_next(&xas)) {
+		struct page *head;
+		if (xas_retry(&xas, page))
+			continue;
+		/*
+		 * If the entry has been swapped out, we can stop looking.
+		 * No current caller is looking for DAX entries.
+		 */
+		if (xa_is_value(page))
 			break;
-		}
 
 		head = compound_head(page);
 		if (!page_cache_get_speculative(head))
-			goto repeat;
+			goto retry;
 
 		/* The page was split under us? */
-		if (compound_head(page) != head) {
-			put_page(head);
-			goto repeat;
-		}
+		if (compound_head(page) != head)
+			goto put_page;
 
 		/* Has the page moved? */
-		if (unlikely(page != *slot)) {
-			put_page(head);
-			goto repeat;
-		}
+		if (unlikely(page != xas_reload(&xas)))
+			goto put_page;
 
 		/*
 		 * must check mapping and index after taking the ref.
 		 * otherwise we can get both false positives and false
 		 * negatives, which is just confusing to the caller.
 		 */
-		if (page->mapping == NULL || page_to_pgoff(page) != iter.index) {
+		if (!page->mapping || page_to_pgoff(page) != xas.xa_index) {
 			put_page(page);
 			break;
 		}
@@ -1779,6 +1765,11 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
 		pages[ret] = page;
 		if (++ret == nr_pages)
 			break;
+		continue;
+put_page:
+		put_page(head);
+retry:
+		xas_reset(&xas);
 	}
 	rcu_read_unlock();
 	return ret;
diff --git a/tools/testing/radix-tree/regression3.c b/tools/testing/radix-tree/regression3.c
index ace2543c3eda..9f9a3b280f56 100644
--- a/tools/testing/radix-tree/regression3.c
+++ b/tools/testing/radix-tree/regression3.c
@@ -69,21 +69,6 @@ void regression3_test(void)
 			continue;
 		}
 	}
-	radix_tree_delete(&root, 1);
-
-	first = true;
-	radix_tree_for_each_contig(slot, &root, &iter, 0) {
-		printv(2, "contig %ld %p\n", iter.index, *slot);
-		if (first) {
-			radix_tree_insert(&root, 1, ptr);
-			first = false;
-		}
-		if (radix_tree_deref_retry(*slot)) {
-			printv(2, "retry at %ld\n", iter.index);
-			slot = radix_tree_iter_retry(&iter);
-			continue;
-		}
-	}
 
 	radix_tree_for_each_slot(slot, &root, &iter, 0) {
 		printv(2, "slot %ld %p\n", iter.index, *slot);
@@ -93,14 +78,6 @@ void regression3_test(void)
 		}
 	}
 
-	radix_tree_for_each_contig(slot, &root, &iter, 0) {
-		printv(2, "contig %ld %p\n", iter.index, *slot);
-		if (!iter.index) {
-			printv(2, "next at %ld\n", iter.index);
-			slot = radix_tree_iter_resume(slot, &iter);
-		}
-	}
-
 	radix_tree_tag_set(&root, 0, 0);
 	radix_tree_tag_set(&root, 1, 0);
 	radix_tree_for_each_tagged(slot, &root, &iter, 0, 0) {
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 28/74] page cache; Convert find_get_pages_range_tag to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (26 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 27/74] page cache: Convert find_get_pages_contig " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 29/74] page cache: Convert find_get_entries_tag " Matthew Wilcox
                   ` (46 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

The 'end' parameter of the xas_for_each iterator avoids a useless
iteration at the end of the range.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/pagemap.h |  4 +--
 mm/filemap.c            | 68 ++++++++++++++++-------------------------
 2 files changed, 28 insertions(+), 44 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 2f5d2d3ebaac..a6d635fefb01 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -363,10 +363,10 @@ static inline unsigned find_get_pages(struct address_space *mapping,
 unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
 			       unsigned int nr_pages, struct page **pages);
 unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
-			pgoff_t end, int tag, unsigned int nr_pages,
+			pgoff_t end, xa_tag_t tag, unsigned int nr_pages,
 			struct page **pages);
 static inline unsigned find_get_pages_tag(struct address_space *mapping,
-			pgoff_t *index, int tag, unsigned int nr_pages,
+			pgoff_t *index, xa_tag_t tag, unsigned int nr_pages,
 			struct page **pages)
 {
 	return find_get_pages_range_tag(mapping, index, (pgoff_t)-1, tag,
diff --git a/mm/filemap.c b/mm/filemap.c
index 8a69613fcdf3..83328635edaa 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1789,74 +1789,58 @@ EXPORT_SYMBOL(find_get_pages_contig);
  * @tag.   We update @index to index the next page for the traversal.
  */
 unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
-			pgoff_t end, int tag, unsigned int nr_pages,
+			pgoff_t end, xa_tag_t tag, unsigned int nr_pages,
 			struct page **pages)
 {
-	struct radix_tree_iter iter;
-	void **slot;
+	XA_STATE(xas, &mapping->i_pages, *index);
+	struct page *page;
 	unsigned ret = 0;
 
 	if (unlikely(!nr_pages))
 		return 0;
 
 	rcu_read_lock();
-	radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, *index, tag) {
-		struct page *head, *page;
-
-		if (iter.index > end)
-			break;
-repeat:
-		page = radix_tree_deref_slot(slot);
-		if (unlikely(!page))
+	xas_for_each_tagged(&xas, page, end, tag) {
+		struct page *head;
+		if (xas_retry(&xas, page))
 			continue;
-
-		if (radix_tree_exception(page)) {
-			if (radix_tree_deref_retry(page)) {
-				slot = radix_tree_iter_retry(&iter);
-				continue;
-			}
-			/*
-			 * A shadow entry of a recently evicted page.
-			 *
-			 * Those entries should never be tagged, but
-			 * this tree walk is lockless and the tags are
-			 * looked up in bulk, one radix tree node at a
-			 * time, so there is a sizable window for page
-			 * reclaim to evict a page we saw tagged.
-			 *
-			 * Skip over it.
-			 */
+		/*
+		 * Shadow entries should never be tagged, but this iteration
+		 * is lockless so there is a window for page reclaim to evict
+		 * a page we saw tagged.  Skip over it.
+		 */
+		if (xa_is_value(page))
 			continue;
-		}
 
 		head = compound_head(page);
 		if (!page_cache_get_speculative(head))
-			goto repeat;
+			goto retry;
 
 		/* The page was split under us? */
-		if (compound_head(page) != head) {
-			put_page(head);
-			goto repeat;
-		}
+		if (compound_head(page) != head)
+			goto put_page;
 
 		/* Has the page moved? */
-		if (unlikely(page != *slot)) {
-			put_page(head);
-			goto repeat;
-		}
+		if (unlikely(page != xas_reload(&xas)))
+			goto put_page;
 
 		pages[ret] = page;
 		if (++ret == nr_pages) {
-			*index = pages[ret - 1]->index + 1;
+			*index = page->index + 1;
 			goto out;
 		}
+		continue;
+put_page:
+		put_page(head);
+retry:
+		xas_reset(&xas);
 	}
 
 	/*
-	 * We come here when we got at @end. We take care to not overflow the
+	 * We come here when we got to @end. We take care to not overflow the
 	 * index @index as it confuses some of the callers. This breaks the
-	 * iteration when there is page at index -1 but that is already broken
-	 * anyway.
+	 * iteration when there is a page at index -1 but that is already
+	 * broken anyway.
 	 */
 	if (end == (pgoff_t)-1)
 		*index = (pgoff_t)-1;
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 29/74] page cache: Convert find_get_entries_tag to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (27 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 28/74] page cache; Convert find_get_pages_range_tag " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 30/74] page cache: Convert filemap_map_pages " Matthew Wilcox
                   ` (45 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Slightly shorter and simpler code.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/pagemap.h |  2 +-
 mm/filemap.c            | 54 ++++++++++++++++++-----------------------
 2 files changed, 25 insertions(+), 31 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index a6d635fefb01..442977811b59 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -373,7 +373,7 @@ static inline unsigned find_get_pages_tag(struct address_space *mapping,
 					nr_pages, pages);
 }
 unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start,
-			int tag, unsigned int nr_entries,
+			xa_tag_t tag, unsigned int nr_entries,
 			struct page **entries, pgoff_t *indices);
 
 struct page *grab_cache_page_write_begin(struct address_space *mapping,
diff --git a/mm/filemap.c b/mm/filemap.c
index 83328635edaa..67f04bcdf9ef 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1866,57 +1866,51 @@ EXPORT_SYMBOL(find_get_pages_range_tag);
  * @tag.
  */
 unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start,
-			int tag, unsigned int nr_entries,
+			xa_tag_t tag, unsigned int nr_entries,
 			struct page **entries, pgoff_t *indices)
 {
-	void **slot;
+	XA_STATE(xas, &mapping->i_pages, start);
+	struct page *page;
 	unsigned int ret = 0;
-	struct radix_tree_iter iter;
 
 	if (!nr_entries)
 		return 0;
 
 	rcu_read_lock();
-	radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, start, tag) {
-		struct page *head, *page;
-repeat:
-		page = radix_tree_deref_slot(slot);
-		if (unlikely(!page))
+	xas_for_each_tagged(&xas, page, ULONG_MAX, tag) {
+		struct page *head;
+		if (xas_retry(&xas, page))
 			continue;
-		if (radix_tree_exception(page)) {
-			if (radix_tree_deref_retry(page)) {
-				slot = radix_tree_iter_retry(&iter);
-				continue;
-			}
-
-			/*
-			 * A shadow entry of a recently evicted page, a swap
-			 * entry from shmem/tmpfs or a DAX entry.  Return it
-			 * without attempting to raise page count.
-			 */
+		/*
+		 * A shadow entry of a recently evicted page, a swap
+		 * entry from shmem/tmpfs or a DAX entry.  Return it
+		 * without attempting to raise page count.
+		 */
+		if (xa_is_value(page))
 			goto export;
-		}
 
 		head = compound_head(page);
 		if (!page_cache_get_speculative(head))
-			goto repeat;
+			goto retry;
 
 		/* The page was split under us? */
-		if (compound_head(page) != head) {
-			put_page(head);
-			goto repeat;
-		}
+		if (compound_head(page) != head)
+			goto put_page;
 
 		/* Has the page moved? */
-		if (unlikely(page != *slot)) {
-			put_page(head);
-			goto repeat;
-		}
+		if (unlikely(page != xas_reload(&xas)))
+			goto put_page;
+
 export:
-		indices[ret] = iter.index;
+		indices[ret] = xas.xa_index;
 		entries[ret] = page;
 		if (++ret == nr_entries)
 			break;
+		continue;
+put_page:
+		put_page(head);
+retry:
+		xas_reset(&xas);
 	}
 	rcu_read_unlock();
 	return ret;
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 30/74] page cache: Convert filemap_map_pages to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (28 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 29/74] page cache: Convert find_get_entries_tag " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 31/74] radix tree test suite: Convert regression1 " Matthew Wilcox
                   ` (44 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Slight change of strategy here; if we have trouble getting hold of a
page for whatever reason (eg a compound page is split underneath us),
don't spin to stabilise the page, just continue the iteration, like we
would if we failed to trylock the page.  Since this is a speculative
optimisation, it feels like we should allow the process to take an extra
fault if it turns out to need this page instead of spending time to pin
down a page it may not need.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/filemap.c | 42 +++++++++++++-----------------------------
 1 file changed, 13 insertions(+), 29 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 67f04bcdf9ef..4204d9df003b 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2516,45 +2516,31 @@ EXPORT_SYMBOL(filemap_fault);
 void filemap_map_pages(struct vm_fault *vmf,
 		pgoff_t start_pgoff, pgoff_t end_pgoff)
 {
-	struct radix_tree_iter iter;
-	void **slot;
 	struct file *file = vmf->vma->vm_file;
 	struct address_space *mapping = file->f_mapping;
 	pgoff_t last_pgoff = start_pgoff;
 	unsigned long max_idx;
+	XA_STATE(xas, &mapping->i_pages, start_pgoff);
 	struct page *head, *page;
 
 	rcu_read_lock();
-	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start_pgoff) {
-		if (iter.index > end_pgoff)
-			break;
-repeat:
-		page = radix_tree_deref_slot(slot);
-		if (unlikely(!page))
-			goto next;
-		if (radix_tree_exception(page)) {
-			if (radix_tree_deref_retry(page)) {
-				slot = radix_tree_iter_retry(&iter);
-				continue;
-			}
+	xas_for_each(&xas, page, end_pgoff) {
+		if (xas_retry(&xas, page))
+			continue;
+		if (xa_is_value(page))
 			goto next;
-		}
 
 		head = compound_head(page);
 		if (!page_cache_get_speculative(head))
-			goto repeat;
+			goto next;
 
 		/* The page was split under us? */
-		if (compound_head(page) != head) {
-			put_page(head);
-			goto repeat;
-		}
+		if (compound_head(page) != head)
+			goto skip;
 
 		/* Has the page moved? */
-		if (unlikely(page != *slot)) {
-			put_page(head);
-			goto repeat;
-		}
+		if (unlikely(page != xas_reload(&xas)))
+			goto skip;
 
 		if (!PageUptodate(page) ||
 				PageReadahead(page) ||
@@ -2573,10 +2559,10 @@ void filemap_map_pages(struct vm_fault *vmf,
 		if (file->f_ra.mmap_miss > 0)
 			file->f_ra.mmap_miss--;
 
-		vmf->address += (iter.index - last_pgoff) << PAGE_SHIFT;
+		vmf->address += (xas.xa_index - last_pgoff) << PAGE_SHIFT;
 		if (vmf->pte)
-			vmf->pte += iter.index - last_pgoff;
-		last_pgoff = iter.index;
+			vmf->pte += xas.xa_index - last_pgoff;
+		last_pgoff = xas.xa_index;
 		if (alloc_set_pte(vmf, NULL, page))
 			goto unlock;
 		unlock_page(page);
@@ -2589,8 +2575,6 @@ void filemap_map_pages(struct vm_fault *vmf,
 		/* Huge page is mapped? No need to proceed. */
 		if (pmd_trans_huge(*vmf->pmd))
 			break;
-		if (iter.index == end_pgoff)
-			break;
 	}
 	rcu_read_unlock();
 }
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 31/74] radix tree test suite: Convert regression1 to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (29 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 30/74] page cache: Convert filemap_map_pages " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 32/74] page cache: Convert delete_batch " Matthew Wilcox
                   ` (43 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Now the page cache lookup is using the XArray, let's convert this
regression test from the radix tree API to the XArray so it's testing
roughly the same thing it was testing before.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 tools/testing/radix-tree/regression1.c | 58 +++++++++-----------------
 1 file changed, 19 insertions(+), 39 deletions(-)

diff --git a/tools/testing/radix-tree/regression1.c b/tools/testing/radix-tree/regression1.c
index 0aece092f40e..b4a4a7168986 100644
--- a/tools/testing/radix-tree/regression1.c
+++ b/tools/testing/radix-tree/regression1.c
@@ -53,12 +53,12 @@ struct page {
 	unsigned long index;
 };
 
-static struct page *page_alloc(void)
+static struct page *page_alloc(int index)
 {
 	struct page *p;
 	p = malloc(sizeof(struct page));
 	p->count = 1;
-	p->index = 1;
+	p->index = index;
 	pthread_mutex_init(&p->lock, NULL);
 
 	return p;
@@ -80,53 +80,33 @@ static void page_free(struct page *p)
 static unsigned find_get_pages(unsigned long start,
 			    unsigned int nr_pages, struct page **pages)
 {
-	unsigned int i;
-	unsigned int ret;
-	unsigned int nr_found;
+	XA_STATE(xas, &mt_tree, start);
+	struct page *page;
+	unsigned int ret = 0;
 
 	rcu_read_lock();
-restart:
-	nr_found = radix_tree_gang_lookup_slot(&mt_tree,
-				(void ***)pages, NULL, start, nr_pages);
-	ret = 0;
-	for (i = 0; i < nr_found; i++) {
-		struct page *page;
-repeat:
-		page = radix_tree_deref_slot((void **)pages[i]);
-		if (unlikely(!page))
+	xas_for_each(&xas, page, ULONG_MAX) {
+		if (xas_retry(&xas, page))
 			continue;
 
-		if (radix_tree_exception(page)) {
-			if (radix_tree_deref_retry(page)) {
-				/*
-				 * Transient condition which can only trigger
-				 * when entry at index 0 moves out of or back
-				 * to root: none yet gotten, safe to restart.
-				 */
-				assert((start | i) == 0);
-				goto restart;
-			}
-			/*
-			 * No exceptional entries are inserted in this test.
-			 */
-			assert(0);
-		}
-
 		pthread_mutex_lock(&page->lock);
-		if (!page->count) {
-			pthread_mutex_unlock(&page->lock);
-			goto repeat;
-		}
+		if (!page->count)
+			goto unlock;
+
 		/* don't actually update page refcount */
 		pthread_mutex_unlock(&page->lock);
 
 		/* Has the page moved? */
-		if (unlikely(page != *((void **)pages[i]))) {
-			goto repeat;
-		}
+		if (unlikely(page != xas_reload(&xas)))
+			goto put_page;
 
 		pages[ret] = page;
 		ret++;
+		continue;
+unlock:
+		pthread_mutex_unlock(&page->lock);
+put_page:
+		xas_reset(&xas);
 	}
 	rcu_read_unlock();
 	return ret;
@@ -145,12 +125,12 @@ static void *regression1_fn(void *arg)
 		for (j = 0; j < 1000000; j++) {
 			struct page *p;
 
-			p = page_alloc();
+			p = page_alloc(0);
 			pthread_mutex_lock(&mt_lock);
 			radix_tree_insert(&mt_tree, 0, p);
 			pthread_mutex_unlock(&mt_lock);
 
-			p = page_alloc();
+			p = page_alloc(1);
 			pthread_mutex_lock(&mt_lock);
 			radix_tree_insert(&mt_tree, 1, p);
 			pthread_mutex_unlock(&mt_lock);
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 32/74] page cache: Convert delete_batch to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (30 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 31/74] radix tree test suite: Convert regression1 " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 33/74] page cache: Remove stray radix comment Matthew Wilcox
                   ` (42 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Rename the function from page_cache_tree_delete_batch to just
page_cache_delete_batch.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/filemap.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 4204d9df003b..025077bc82be 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -272,7 +272,7 @@ void delete_from_page_cache(struct page *page)
 EXPORT_SYMBOL(delete_from_page_cache);
 
 /*
- * page_cache_tree_delete_batch - delete several pages from page cache
+ * page_cache_delete_batch - delete several pages from page cache
  * @mapping: the mapping to which pages belong
  * @pvec: pagevec with pages to delete
  *
@@ -285,23 +285,18 @@ EXPORT_SYMBOL(delete_from_page_cache);
  *
  * The function expects the i_pages lock to be held.
  */
-static void
-page_cache_tree_delete_batch(struct address_space *mapping,
+static void page_cache_delete_batch(struct address_space *mapping,
 			     struct pagevec *pvec)
 {
-	struct radix_tree_iter iter;
-	void **slot;
+	XA_STATE(xas, &mapping->i_pages, pvec->pages[0]->index);
 	int total_pages = 0;
 	int i = 0, tail_pages = 0;
 	struct page *page;
-	pgoff_t start;
 
-	start = pvec->pages[0]->index;
-	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
+	mapping_set_update(&xas, mapping);
+	xas_for_each(&xas, page, ULONG_MAX) {
 		if (i >= pagevec_count(pvec) && !tail_pages)
 			break;
-		page = radix_tree_deref_slot_protected(slot,
-						       &mapping->i_pages.xa_lock);
 		if (xa_is_value(page))
 			continue;
 		if (!tail_pages) {
@@ -310,8 +305,11 @@ page_cache_tree_delete_batch(struct address_space *mapping,
 			 * have our pages locked so they are protected from
 			 * being removed.
 			 */
-			if (page != pvec->pages[i])
+			if (page != pvec->pages[i]) {
+				VM_BUG_ON_PAGE(page->index >
+						pvec->pages[i]->index, page);
 				continue;
+			}
 			WARN_ON_ONCE(!PageLocked(page));
 			if (PageTransHuge(page) && !PageHuge(page))
 				tail_pages = HPAGE_PMD_NR - 1;
@@ -322,11 +320,11 @@ page_cache_tree_delete_batch(struct address_space *mapping,
 			 */
 			i++;
 		} else {
+			VM_BUG_ON_PAGE(page->index + HPAGE_PMD_NR - tail_pages
+					!= pvec->pages[i]->index, page);
 			tail_pages--;
 		}
-		radix_tree_clear_tags(&mapping->i_pages, iter.node, slot);
-		__radix_tree_replace(&mapping->i_pages, iter.node, slot, NULL,
-				workingset_lookup_update(mapping));
+		xas_store(&xas, NULL);
 		total_pages++;
 	}
 	mapping->nrpages -= total_pages;
@@ -347,7 +345,7 @@ void delete_from_page_cache_batch(struct address_space *mapping,
 
 		unaccount_page_cache_page(mapping, pvec->pages[i]);
 	}
-	page_cache_tree_delete_batch(mapping, pvec);
+	page_cache_delete_batch(mapping, pvec);
 	xa_unlock_irqrestore(&mapping->i_pages, flags);
 
 	for (i = 0; i < pagevec_count(pvec); i++)
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 33/74] page cache: Remove stray radix comment
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (31 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 32/74] page cache: Convert delete_batch " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 34/74] page cache: Convert filemap_range_has_page to XArray Matthew Wilcox
                   ` (41 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/filemap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 025077bc82be..e447dd2d0f5c 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2682,7 +2682,7 @@ static struct page *do_read_cache_page(struct address_space *mapping,
 			put_page(page);
 			if (err == -EEXIST)
 				goto repeat;
-			/* Presumably ENOMEM for radix tree node */
+			/* Presumably ENOMEM for xarray node */
 			return ERR_PTR(err);
 		}
 
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 34/74] page cache: Convert filemap_range_has_page to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (32 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 33/74] page cache: Remove stray radix comment Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 35/74] mm: Convert page-writeback " Matthew Wilcox
                   ` (40 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Instead of calling find_get_pages_range() and putting any reference,
use xas_find() to iterate over any entries in the range, skipping the
shadow/swap entries.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/filemap.c | 26 ++++++++++++++++++--------
 1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index e447dd2d0f5c..68890327d1f2 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -455,20 +455,30 @@ EXPORT_SYMBOL(filemap_flush);
 bool filemap_range_has_page(struct address_space *mapping,
 			   loff_t start_byte, loff_t end_byte)
 {
-	pgoff_t index = start_byte >> PAGE_SHIFT;
-	pgoff_t end = end_byte >> PAGE_SHIFT;
 	struct page *page;
+	XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT);
+	pgoff_t max = end_byte >> PAGE_SHIFT;
 
 	if (end_byte < start_byte)
 		return false;
 
-	if (mapping->nrpages == 0)
-		return false;
+	rcu_read_lock();
+	do {
+		page = xas_find(&xas, max);
+		if (xas_retry(&xas, page))
+			continue;
+		/* Shadow entries don't count */
+		if (xa_is_value(page))
+			continue;
+		/*
+		 * We don't need to try to pin this page; we're about to
+		 * release the RCU lock anyway.  It is enough to know that
+		 * there was a page here recently.
+		 */
+	} while (0);
+	rcu_read_unlock();
 
-	if (!find_get_pages_range(mapping, &index, end, 1, &page))
-		return false;
-	put_page(page);
-	return true;
+	return page != NULL;
 }
 EXPORT_SYMBOL(filemap_range_has_page);
 
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 35/74] mm: Convert page-writeback to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (33 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 34/74] page cache: Convert filemap_range_has_page to XArray Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 36/74] mm: Convert workingset " Matthew Wilcox
                   ` (39 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Includes moving mapping_tagged() to fs.h as a static inline, and
changing it to return bool.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/fs.h  | 17 ++++++-----
 mm/page-writeback.c | 72 ++++++++++++++++-----------------------------
 2 files changed, 36 insertions(+), 53 deletions(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index f1716ce5ff6f..3fe2d7607d65 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -476,15 +476,18 @@ struct block_device {
 	struct mutex		bd_fsfreeze_mutex;
 } __randomize_layout;
 
+/* XArray tags, for tagging dirty and writeback pages in the pagecache. */
+#define PAGECACHE_TAG_DIRTY	XA_TAG_0
+#define PAGECACHE_TAG_WRITEBACK	XA_TAG_1
+#define PAGECACHE_TAG_TOWRITE	XA_TAG_2
+
 /*
- * Radix-tree tags, for tagging dirty and writeback pages within the pagecache
- * radix trees
+ * Returns true if any of the pages in the mapping are marked with the tag.
  */
-#define PAGECACHE_TAG_DIRTY	0
-#define PAGECACHE_TAG_WRITEBACK	1
-#define PAGECACHE_TAG_TOWRITE	2
-
-int mapping_tagged(struct address_space *mapping, int tag);
+static inline bool mapping_tagged(struct address_space *mapping, xa_tag_t tag)
+{
+	return xa_tagged(&mapping->i_pages, tag);
+}
 
 static inline void i_mmap_lock_write(struct address_space *mapping)
 {
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 337c6afb3345..0e502bd13ad9 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2098,34 +2098,25 @@ void __init page_writeback_init(void)
  * dirty pages in the file (thus it is important for this function to be quick
  * so that it can tag pages faster than a dirtying process can create them).
  */
-/*
- * We tag pages in batches of WRITEBACK_TAG_BATCH to reduce the i_pages lock
- * latency.
- */
 void tag_pages_for_writeback(struct address_space *mapping,
 			     pgoff_t start, pgoff_t end)
 {
-#define WRITEBACK_TAG_BATCH 4096
-	unsigned long tagged = 0;
-	struct radix_tree_iter iter;
-	void **slot;
+	XA_STATE(xas, &mapping->i_pages, start);
+	unsigned int tagged = 0;
+	void *page;
 
-	xa_lock_irq(&mapping->i_pages);
-	radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, start,
-							PAGECACHE_TAG_DIRTY) {
-		if (iter.index > end)
-			break;
-		radix_tree_iter_tag_set(&mapping->i_pages, &iter,
-							PAGECACHE_TAG_TOWRITE);
-		tagged++;
-		if ((tagged % WRITEBACK_TAG_BATCH) != 0)
+	xas_lock_irq(&xas);
+	xas_for_each_tagged(&xas, page, end, PAGECACHE_TAG_DIRTY) {
+		xas_set_tag(&xas, PAGECACHE_TAG_TOWRITE);
+		if (++tagged % XA_CHECK_SCHED)
 			continue;
-		slot = radix_tree_iter_resume(slot, &iter);
-		xa_unlock_irq(&mapping->i_pages);
+
+		xas_pause(&xas);
+		xas_unlock_irq(&xas);
 		cond_resched();
-		xa_lock_irq(&mapping->i_pages);
+		xas_lock_irq(&xas);
 	}
-	xa_unlock_irq(&mapping->i_pages);
+	xas_unlock_irq(&xas);
 }
 EXPORT_SYMBOL(tag_pages_for_writeback);
 
@@ -2165,7 +2156,7 @@ int write_cache_pages(struct address_space *mapping,
 	pgoff_t done_index;
 	int cycled;
 	int range_whole = 0;
-	int tag;
+	xa_tag_t tag;
 
 	pagevec_init(&pvec);
 	if (wbc->range_cyclic) {
@@ -2446,7 +2437,7 @@ void account_page_cleaned(struct page *page, struct address_space *mapping,
 
 /*
  * For address_spaces which do not use buffers.  Just tag the page as dirty in
- * its radix tree.
+ * the xarray.
  *
  * This is also used when a single buffer is being dirtied: we want to set the
  * page dirty in that case, but not all the buffers.  This is a "bottom-up"
@@ -2472,7 +2463,7 @@ int __set_page_dirty_nobuffers(struct page *page)
 		BUG_ON(page_mapping(page) != mapping);
 		WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page));
 		account_page_dirtied(page, mapping);
-		radix_tree_tag_set(&mapping->i_pages, page_index(page),
+		__xa_set_tag(&mapping->i_pages, page_index(page),
 				   PAGECACHE_TAG_DIRTY);
 		xa_unlock_irqrestore(&mapping->i_pages, flags);
 		unlock_page_memcg(page);
@@ -2635,13 +2626,13 @@ EXPORT_SYMBOL(__cancel_dirty_page);
  * Returns true if the page was previously dirty.
  *
  * This is for preparing to put the page under writeout.  We leave the page
- * tagged as dirty in the radix tree so that a concurrent write-for-sync
+ * tagged as dirty in the xarray so that a concurrent write-for-sync
  * can discover it via a PAGECACHE_TAG_DIRTY walk.  The ->writepage
  * implementation will run either set_page_writeback() or set_page_dirty(),
- * at which stage we bring the page's dirty flag and radix-tree dirty tag
+ * at which stage we bring the page's dirty flag and xarray dirty tag
  * back into sync.
  *
- * This incoherency between the page's dirty flag and radix-tree tag is
+ * This incoherency between the page's dirty flag and xarray tag is
  * unfortunate, but it only exists while the page is locked.
  */
 int clear_page_dirty_for_io(struct page *page)
@@ -2722,7 +2713,7 @@ int test_clear_page_writeback(struct page *page)
 		xa_lock_irqsave(&mapping->i_pages, flags);
 		ret = TestClearPageWriteback(page);
 		if (ret) {
-			radix_tree_tag_clear(&mapping->i_pages, page_index(page),
+			__xa_clear_tag(&mapping->i_pages, page_index(page),
 						PAGECACHE_TAG_WRITEBACK);
 			if (bdi_cap_account_writeback(bdi)) {
 				struct bdi_writeback *wb = inode_to_wb(inode);
@@ -2762,11 +2753,13 @@ int __test_set_page_writeback(struct page *page, bool keep_write)
 
 	lock_page_memcg(page);
 	if (mapping && mapping_use_writeback_tags(mapping)) {
+		XA_STATE(xas, &mapping->i_pages, page_index(page));
 		struct inode *inode = mapping->host;
 		struct backing_dev_info *bdi = inode_to_bdi(inode);
 		unsigned long flags;
 
-		xa_lock_irqsave(&mapping->i_pages, flags);
+		xas_lock_irqsave(&xas, flags);
+		xas_load(&xas);
 		ret = TestSetPageWriteback(page);
 		if (!ret) {
 			bool on_wblist;
@@ -2774,8 +2767,7 @@ int __test_set_page_writeback(struct page *page, bool keep_write)
 			on_wblist = mapping_tagged(mapping,
 						   PAGECACHE_TAG_WRITEBACK);
 
-			radix_tree_tag_set(&mapping->i_pages, page_index(page),
-						PAGECACHE_TAG_WRITEBACK);
+			xas_set_tag(&xas, PAGECACHE_TAG_WRITEBACK);
 			if (bdi_cap_account_writeback(bdi))
 				inc_wb_stat(inode_to_wb(inode), WB_WRITEBACK);
 
@@ -2788,12 +2780,10 @@ int __test_set_page_writeback(struct page *page, bool keep_write)
 				sb_mark_inode_writeback(mapping->host);
 		}
 		if (!PageDirty(page))
-			radix_tree_tag_clear(&mapping->i_pages, page_index(page),
-						PAGECACHE_TAG_DIRTY);
+			xas_clear_tag(&xas, PAGECACHE_TAG_DIRTY);
 		if (!keep_write)
-			radix_tree_tag_clear(&mapping->i_pages, page_index(page),
-						PAGECACHE_TAG_TOWRITE);
-		xa_unlock_irqrestore(&mapping->i_pages, flags);
+			xas_clear_tag(&xas, PAGECACHE_TAG_TOWRITE);
+		xas_unlock_irqrestore(&xas, flags);
 	} else {
 		ret = TestSetPageWriteback(page);
 	}
@@ -2807,16 +2797,6 @@ int __test_set_page_writeback(struct page *page, bool keep_write)
 }
 EXPORT_SYMBOL(__test_set_page_writeback);
 
-/*
- * Return true if any of the pages in the mapping are marked with the
- * passed tag.
- */
-int mapping_tagged(struct address_space *mapping, int tag)
-{
-	return radix_tree_tagged(&mapping->i_pages, tag);
-}
-EXPORT_SYMBOL(mapping_tagged);
-
 /**
  * wait_for_stable_page() - wait for writeback to finish, if necessary.
  * @page:	The page to wait on.
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 36/74] mm: Convert workingset to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (34 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 35/74] mm: Convert page-writeback " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 37/74] mm: Convert truncate " Matthew Wilcox
                   ` (38 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

We construct an XA_STATE and use it to delete the node with
xas_store() rather than adding a special function for this unique
use case.  Includes a test that simulates this usage for the
test suite.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/swap.h |  9 -------
 lib/test_xarray.c    | 61 ++++++++++++++++++++++++++++++++++++++++++++
 mm/workingset.c      | 51 +++++++++++++++---------------------
 3 files changed, 82 insertions(+), 39 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 1b91e7f7bdeb..a450a1d40b19 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -307,15 +307,6 @@ void workingset_update_node(struct xa_node *node);
 		xas_set_update(xas, workingset_update_node);		\
 } while (0)
 
-/* Returns workingset_update_node() if the mapping has shadow entries. */
-#define workingset_lookup_update(mapping)				\
-({									\
-	radix_tree_update_node_t __helper = workingset_update_node;	\
-	if (dax_mapping(mapping) || shmem_mapping(mapping))		\
-		__helper = NULL;					\
-	__helper;							\
-})
-
 /* linux/mm/page_alloc.c */
 extern unsigned long totalram_pages;
 extern unsigned long totalreserve_pages;
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index 818cfd8746ba..0ac0c8108ef4 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -554,6 +554,63 @@ static void check_move(struct xarray *xa)
 		check_move_small(xa, (1UL << i) - 1);
 }
 
+static LIST_HEAD(shadow_nodes);
+
+static void test_update_node(struct xa_node *node)
+{
+	if (node->count && node->count == node->nr_values) {
+		if (list_empty(&node->private_list))
+			list_add(&shadow_nodes, &node->private_list);
+	} else {
+		if (!list_empty(&node->private_list))
+			list_del_init(&node->private_list);
+	}
+}
+
+static void shadow_remove(struct xarray *xa)
+{
+	struct xa_node *node;
+
+	while ((node = list_first_entry_or_null(&shadow_nodes,
+					struct xa_node, private_list))) {
+		XA_STATE(xas, node->array, 0);
+		XA_BUG_ON(xa, node->array != xa);
+		list_del_init(&node->private_list);
+		xas.xa_node = xa_parent_locked(node->array, node);
+		xas.xa_offset = node->offset;
+		xas.xa_shift = node->shift + XA_CHUNK_SHIFT;
+		xas_set_update(&xas, test_update_node);
+		xas_store(&xas, NULL);
+	}
+}
+
+static void check_workingset(struct xarray *xa, unsigned long index)
+{
+	XA_STATE(xas, xa, index);
+	xas_set_update(&xas, test_update_node);
+
+	do {
+		xas_store(&xas, xa_mk_value(0));
+	} while (xas_nomem(&xas, GFP_KERNEL));
+
+	xas_next(&xas);
+	do {
+		xas_store(&xas, xa_mk_value(1));
+	} while (xas_nomem(&xas, GFP_KERNEL));
+	XA_BUG_ON(xa, list_empty(&shadow_nodes));
+
+	xas_next(&xas);
+	xas_store(&xas, &xas);
+	XA_BUG_ON(xa, !list_empty(&shadow_nodes));
+
+	xas_store(&xas, xa_mk_value(2));
+	XA_BUG_ON(xa, list_empty(&shadow_nodes));
+
+	shadow_remove(xa);
+	XA_BUG_ON(xa, !list_empty(&shadow_nodes));
+	XA_BUG_ON(xa, !xa_empty(xa));
+}
+
 static int xarray_checks(void)
 {
 	DEFINE_XARRAY(array);
@@ -570,6 +627,10 @@ static int xarray_checks(void)
 	check_move(&array);
 	check_store_iter(&array);
 
+	check_workingset(&array, 0);
+	check_workingset(&array, 64);
+	check_workingset(&array, 4096);
+
 	printk("XArray: %u of %u tests passed\n", tests_passed, tests_run);
 	return (tests_run != tests_passed) ? 0 : -EINVAL;
 }
diff --git a/mm/workingset.c b/mm/workingset.c
index bad4e58881cd..f7fc5456fa77 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -148,7 +148,7 @@
  * and activations is maintained (node->inactive_age).
  *
  * On eviction, a snapshot of this counter (along with some bits to
- * identify the node) is stored in the now empty page cache radix tree
+ * identify the node) is stored in the now empty page cache
  * slot of the evicted page.  This is called a shadow entry.
  *
  * On cache misses for which there are shadow entries, an eligible
@@ -162,7 +162,7 @@
 
 /*
  * Eviction timestamps need to be able to cover the full range of
- * actionable refaults. However, bits are tight in the radix tree
+ * actionable refaults. However, bits are tight in the xarray
  * entry, and after storing the identifier for the lruvec there might
  * not be enough left to represent every single actionable refault. In
  * that case, we have to sacrifice granularity for distance, and group
@@ -338,7 +338,7 @@ void workingset_activation(struct page *page)
 
 static struct list_lru shadow_nodes;
 
-void workingset_update_node(struct radix_tree_node *node)
+void workingset_update_node(struct xa_node *node)
 {
 	/*
 	 * Track non-empty nodes that contain only shadow entries;
@@ -370,7 +370,7 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 	local_irq_enable();
 
 	/*
-	 * Approximate a reasonable limit for the radix tree nodes
+	 * Approximate a reasonable limit for the nodes
 	 * containing shadow entries. We don't need to keep more
 	 * shadow entries than possible pages on the active list,
 	 * since refault distances bigger than that are dismissed.
@@ -385,11 +385,11 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 	 * worst-case density of 1/8th. Below that, not all eligible
 	 * refaults can be detected anymore.
 	 *
-	 * On 64-bit with 7 radix_tree_nodes per page and 64 slots
+	 * On 64-bit with 7 xa_nodes per page and 64 slots
 	 * each, this will reclaim shadow entries when they consume
 	 * ~1.8% of available memory:
 	 *
-	 * PAGE_SIZE / radix_tree_nodes / node_entries * 8 / PAGE_SIZE
+	 * PAGE_SIZE / xa_nodes / node_entries * 8 / PAGE_SIZE
 	 */
 	if (sc->memcg) {
 		cache = mem_cgroup_node_nr_lru_pages(sc->memcg, sc->nid,
@@ -398,7 +398,7 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 		cache = node_page_state(NODE_DATA(sc->nid), NR_ACTIVE_FILE) +
 			node_page_state(NODE_DATA(sc->nid), NR_INACTIVE_FILE);
 	}
-	max_nodes = cache >> (RADIX_TREE_MAP_SHIFT - 3);
+	max_nodes = cache >> (XA_CHUNK_SHIFT - 3);
 
 	if (nodes <= max_nodes)
 		return 0;
@@ -408,11 +408,11 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 static enum lru_status shadow_lru_isolate(struct list_head *item,
 					  struct list_lru_one *lru,
 					  spinlock_t *lru_lock,
-					  void *arg)
+					  void *arg) __must_hold(lru_lock)
 {
+	struct xa_node *node = container_of(item, struct xa_node, private_list);
+	XA_STATE(xas, node->array, 0);
 	struct address_space *mapping;
-	struct radix_tree_node *node;
-	unsigned int i;
 	int ret;
 
 	/*
@@ -420,14 +420,13 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
 	 * the shadow node LRU under the i_pages lock and the
 	 * lru_lock.  Because the page cache tree is emptied before
 	 * the inode can be destroyed, holding the lru_lock pins any
-	 * address_space that has radix tree nodes on the LRU.
+	 * address_space that has nodes on the LRU.
 	 *
 	 * We can then safely transition to the i_pages lock to
 	 * pin only the address_space of the particular node we want
 	 * to reclaim, take the node off-LRU, and drop the lru_lock.
 	 */
 
-	node = container_of(item, struct xa_node, private_list);
 	mapping = container_of(node->array, struct address_space, i_pages);
 
 	/* Coming from the list, invert the lock order */
@@ -449,25 +448,17 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
 		goto out_invalid;
 	if (WARN_ON_ONCE(node->count != node->nr_values))
 		goto out_invalid;
-	for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
-		if (node->slots[i]) {
-			if (WARN_ON_ONCE(!xa_is_value(node->slots[i])))
-				goto out_invalid;
-			if (WARN_ON_ONCE(!node->nr_values))
-				goto out_invalid;
-			if (WARN_ON_ONCE(!mapping->nrexceptional))
-				goto out_invalid;
-			node->slots[i] = NULL;
-			node->nr_values--;
-			node->count--;
-			mapping->nrexceptional--;
-		}
-	}
-	if (WARN_ON_ONCE(node->nr_values))
-		goto out_invalid;
+	mapping->nrexceptional -= node->nr_values;
+	xas.xa_node = xa_parent_locked(&mapping->i_pages, node);
+	xas.xa_offset = node->offset;
+	xas.xa_shift = node->shift + XA_CHUNK_SHIFT;
+	xas_set_update(&xas, workingset_update_node);
+	/*
+	 * We could store a shadow entry here which was the minimum of the
+	 * shadow entries we were tracking ...
+	 */
+	xas_store(&xas, NULL);
 	inc_lruvec_page_state(virt_to_page(node), WORKINGSET_NODERECLAIM);
-	__radix_tree_delete_node(&mapping->i_pages, node,
-				 workingset_lookup_update(mapping));
 
 out_invalid:
 	xa_unlock(&mapping->i_pages);
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 37/74] mm: Convert truncate to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (35 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 36/74] mm: Convert workingset " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 38/74] mm: Convert add_to_swap_cache " Matthew Wilcox
                   ` (37 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

This is essentially xa_cmpxchg() with the locking handled above us,
and it doesn't have to handle replacing a NULL entry.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/truncate.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/mm/truncate.c b/mm/truncate.c
index ed778555c9f3..45d68e90b703 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -33,15 +33,12 @@
 static inline void __clear_shadow_entry(struct address_space *mapping,
 				pgoff_t index, void *entry)
 {
-	struct radix_tree_node *node;
-	void **slot;
+	XA_STATE(xas, &mapping->i_pages, index);
 
-	if (!__radix_tree_lookup(&mapping->i_pages, index, &node, &slot))
+	xas_set_update(&xas, workingset_update_node);
+	if (xas_load(&xas) != entry)
 		return;
-	if (*slot != entry)
-		return;
-	__radix_tree_replace(&mapping->i_pages, node, slot, NULL,
-			     workingset_update_node);
+	xas_store(&xas, NULL);
 	mapping->nrexceptional--;
 }
 
@@ -738,10 +735,10 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
 		index++;
 	}
 	/*
-	 * For DAX we invalidate page tables after invalidating radix tree.  We
+	 * For DAX we invalidate page tables after invalidating page cache.  We
 	 * could invalidate page tables while invalidating each entry however
 	 * that would be expensive. And doing range unmapping before doesn't
-	 * work as we have no cheap way to find whether radix tree entry didn't
+	 * work as we have no cheap way to find whether page cache entry didn't
 	 * get remapped later.
 	 */
 	if (dax_mapping(mapping)) {
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 38/74] mm: Convert add_to_swap_cache to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (36 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 37/74] mm: Convert truncate " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 39/74] mm: Convert delete_from_swap_cache " Matthew Wilcox
                   ` (36 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Combine __add_to_swap_cache and add_to_swap_cache into one function
since there is no more need to preload.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/swap_state.c | 93 +++++++++++++++----------------------------------
 1 file changed, 29 insertions(+), 64 deletions(-)

diff --git a/mm/swap_state.c b/mm/swap_state.c
index dc312559f7df..ca18407a79aa 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -107,14 +107,15 @@ void show_swap_cache_info(void)
 }
 
 /*
- * __add_to_swap_cache resembles add_to_page_cache_locked on swapper_space,
+ * add_to_swap_cache resembles add_to_page_cache_locked on swapper_space,
  * but sets SwapCache flag and private instead of mapping and index.
  */
-int __add_to_swap_cache(struct page *page, swp_entry_t entry)
+int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp)
 {
-	int error, i, nr = hpage_nr_pages(page);
-	struct address_space *address_space;
+	struct address_space *address_space = swap_address_space(entry);
 	pgoff_t idx = swp_offset(entry);
+	XA_STATE(xas, &address_space->i_pages, idx);
+	unsigned long i, nr = 1UL << compound_order(page);
 
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	VM_BUG_ON_PAGE(PageSwapCache(page), page);
@@ -123,50 +124,30 @@ int __add_to_swap_cache(struct page *page, swp_entry_t entry)
 	page_ref_add(page, nr);
 	SetPageSwapCache(page);
 
-	address_space = swap_address_space(entry);
-	xa_lock_irq(&address_space->i_pages);
-	for (i = 0; i < nr; i++) {
-		set_page_private(page + i, entry.val + i);
-		error = radix_tree_insert(&address_space->i_pages,
-					  idx + i, page + i);
-		if (unlikely(error))
-			break;
-	}
-	if (likely(!error)) {
+	do {
+		xas_lock_irq(&xas);
+		xas_create_range(&xas, idx + nr - 1);
+		if (xas_error(&xas))
+			goto unlock;
+		for (i = 0; i < nr; i++) {
+			VM_BUG_ON_PAGE(xas.xa_index != idx + i, page);
+			set_page_private(page + i, entry.val + i);
+			xas_store(&xas, page + i);
+			xas_next(&xas);
+		}
 		address_space->nrpages += nr;
 		__mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr);
 		ADD_CACHE_INFO(add_total, nr);
-	} else {
-		/*
-		 * Only the context which have set SWAP_HAS_CACHE flag
-		 * would call add_to_swap_cache().
-		 * So add_to_swap_cache() doesn't returns -EEXIST.
-		 */
-		VM_BUG_ON(error == -EEXIST);
-		set_page_private(page + i, 0UL);
-		while (i--) {
-			radix_tree_delete(&address_space->i_pages, idx + i);
-			set_page_private(page + i, 0UL);
-		}
-		ClearPageSwapCache(page);
-		page_ref_sub(page, nr);
-	}
-	xa_unlock_irq(&address_space->i_pages);
+unlock:
+		xas_unlock_irq(&xas);
+	} while (xas_nomem(&xas, gfp));
 
-	return error;
-}
-
-
-int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp_mask)
-{
-	int error;
+	if (!xas_error(&xas))
+		return 0;
 
-	error = radix_tree_maybe_preload_order(gfp_mask, compound_order(page));
-	if (!error) {
-		error = __add_to_swap_cache(page, entry);
-		radix_tree_preload_end();
-	}
-	return error;
+	ClearPageSwapCache(page);
+	page_ref_sub(page, nr);
+	return xas_error(&xas);
 }
 
 /*
@@ -217,7 +198,7 @@ int add_to_swap(struct page *page)
 		return 0;
 
 	/*
-	 * Radix-tree node allocations from PF_MEMALLOC contexts could
+	 * XArray node allocations from PF_MEMALLOC contexts could
 	 * completely exhaust the page allocator. __GFP_NOMEMALLOC
 	 * stops emergency reserves from being allocated.
 	 *
@@ -229,7 +210,6 @@ int add_to_swap(struct page *page)
 	 */
 	err = add_to_swap_cache(page, entry,
 			__GFP_HIGH|__GFP_NOMEMALLOC|__GFP_NOWARN);
-	/* -ENOMEM radix-tree allocation failure */
 	if (err)
 		/*
 		 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
@@ -423,19 +403,11 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
 				break;		/* Out of memory */
 		}
 
-		/*
-		 * call radix_tree_preload() while we can wait.
-		 */
-		err = radix_tree_maybe_preload(gfp_mask & GFP_KERNEL);
-		if (err)
-			break;
-
 		/*
 		 * Swap entry may have been freed since our caller observed it.
 		 */
 		err = swapcache_prepare(entry);
 		if (err == -EEXIST) {
-			radix_tree_preload_end();
 			/*
 			 * We might race against get_swap_page() and stumble
 			 * across a SWAP_HAS_CACHE swap_map entry whose page
@@ -443,26 +415,19 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
 			 */
 			cond_resched();
 			continue;
-		}
-		if (err) {		/* swp entry is obsolete ? */
-			radix_tree_preload_end();
+		} else if (err)		/* swp entry is obsolete ? */
 			break;
-		}
 
-		/* May fail (-ENOMEM) if radix-tree node allocation failed. */
+		/* May fail (-ENOMEM) if XArray node allocation failed. */
 		__SetPageLocked(new_page);
 		__SetPageSwapBacked(new_page);
-		err = __add_to_swap_cache(new_page, entry);
+		err = add_to_swap_cache(new_page, entry, gfp_mask & GFP_KERNEL);
 		if (likely(!err)) {
-			radix_tree_preload_end();
-			/*
-			 * Initiate read into locked page and return.
-			 */
+			/* Initiate read into locked page */
 			lru_cache_add_anon(new_page);
 			*new_page_allocated = true;
 			return new_page;
 		}
-		radix_tree_preload_end();
 		__ClearPageLocked(new_page);
 		/*
 		 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 39/74] mm: Convert delete_from_swap_cache to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (37 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 38/74] mm: Convert add_to_swap_cache " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 40/74] mm: Convert __do_page_cache_readahead " Matthew Wilcox
                   ` (35 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Both callers of __delete_from_swap_cache have the swp_entry_t already,
so pass that in to make constructing the XA_STATE easier.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/swap.h |  5 +++--
 mm/swap_state.c      | 24 ++++++++++--------------
 mm/vmscan.c          |  2 +-
 3 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index a450a1d40b19..470570dac9e8 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -404,7 +404,7 @@ extern void show_swap_cache_info(void);
 extern int add_to_swap(struct page *page);
 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
 extern int __add_to_swap_cache(struct page *page, swp_entry_t entry);
-extern void __delete_from_swap_cache(struct page *);
+extern void __delete_from_swap_cache(struct page *, swp_entry_t entry);
 extern void delete_from_swap_cache(struct page *);
 extern void free_page_and_swap_cache(struct page *);
 extern void free_pages_and_swap_cache(struct page **, int);
@@ -564,7 +564,8 @@ static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 	return -1;
 }
 
-static inline void __delete_from_swap_cache(struct page *page)
+static inline void __delete_from_swap_cache(struct page *page,
+							swp_entry_t entry)
 {
 }
 
diff --git a/mm/swap_state.c b/mm/swap_state.c
index ca18407a79aa..5cd42d05177e 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -154,23 +154,22 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp)
  * This must be called only on pages that have
  * been verified to be in the swap cache.
  */
-void __delete_from_swap_cache(struct page *page)
+void __delete_from_swap_cache(struct page *page, swp_entry_t entry)
 {
-	struct address_space *address_space;
+	struct address_space *address_space = swap_address_space(entry);
 	int i, nr = hpage_nr_pages(page);
-	swp_entry_t entry;
-	pgoff_t idx;
+	pgoff_t idx = swp_offset(entry);
+	XA_STATE(xas, &address_space->i_pages, idx);
 
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
 	VM_BUG_ON_PAGE(PageWriteback(page), page);
 
-	entry.val = page_private(page);
-	address_space = swap_address_space(entry);
-	idx = swp_offset(entry);
 	for (i = 0; i < nr; i++) {
-		radix_tree_delete(&address_space->i_pages, idx + i);
+		void *entry = xas_store(&xas, NULL);
+		VM_BUG_ON_PAGE(entry != page + i, entry);
 		set_page_private(page + i, 0);
+		xas_next(&xas);
 	}
 	ClearPageSwapCache(page);
 	address_space->nrpages -= nr;
@@ -243,14 +242,11 @@ int add_to_swap(struct page *page)
  */
 void delete_from_swap_cache(struct page *page)
 {
-	swp_entry_t entry;
-	struct address_space *address_space;
-
-	entry.val = page_private(page);
+	swp_entry_t entry = { .val = page_private(page) };
+	struct address_space *address_space = swap_address_space(entry);
 
-	address_space = swap_address_space(entry);
 	xa_lock_irq(&address_space->i_pages);
-	__delete_from_swap_cache(page);
+	__delete_from_swap_cache(page, entry);
 	xa_unlock_irq(&address_space->i_pages);
 
 	put_swap_page(page, entry);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 03822f86f288..0448b1b366d9 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -753,7 +753,7 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
 	if (PageSwapCache(page)) {
 		swp_entry_t swap = { .val = page_private(page) };
 		mem_cgroup_swapout(page, swap);
-		__delete_from_swap_cache(page);
+		__delete_from_swap_cache(page, swap);
 		xa_unlock_irqrestore(&mapping->i_pages, flags);
 		put_swap_page(page, swap);
 	} else {
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 40/74] mm: Convert __do_page_cache_readahead to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (38 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 39/74] mm: Convert delete_from_swap_cache " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 41/74] mm: Convert page migration " Matthew Wilcox
                   ` (34 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

This one is trivial.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/readahead.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/readahead.c b/mm/readahead.c
index 59998ca31f2a..07f9734dc79f 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -174,9 +174,7 @@ unsigned int __do_page_cache_readahead(struct address_space *mapping,
 		if (page_offset > end_index)
 			break;
 
-		rcu_read_lock();
-		page = radix_tree_lookup(&mapping->i_pages, page_offset);
-		rcu_read_unlock();
+		page = xa_load(&mapping->i_pages, page_offset);
 		if (page && !xa_is_value(page)) {
 			/*
 			 * Page already present?  Kick off the current batch of
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 41/74] mm: Convert page migration to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (39 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 40/74] mm: Convert __do_page_cache_readahead " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 42/74] mm: Convert huge_memory " Matthew Wilcox
                   ` (33 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/migrate.c | 48 ++++++++++++++++++------------------------------
 1 file changed, 18 insertions(+), 30 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 8c0af0f7cab1..80dc5b8c9738 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -323,7 +323,7 @@ void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
 	page = migration_entry_to_page(entry);
 
 	/*
-	 * Once radix-tree replacement of page migration started, page_count
+	 * Once page cache replacement of page migration started, page_count
 	 * *must* be zero. And, we don't want to call wait_on_page_locked()
 	 * against a page without get_page().
 	 * So, we use get_page_unless_zero(), here. Even failed, page fault
@@ -438,10 +438,10 @@ int migrate_page_move_mapping(struct address_space *mapping,
 		struct buffer_head *head, enum migrate_mode mode,
 		int extra_count)
 {
+	XA_STATE(xas, &mapping->i_pages, page_index(page));
 	struct zone *oldzone, *newzone;
 	int dirty;
 	int expected_count = 1 + extra_count;
-	void **pslot;
 
 	/*
 	 * Device public or private pages have an extra refcount as they are
@@ -467,21 +467,16 @@ int migrate_page_move_mapping(struct address_space *mapping,
 	oldzone = page_zone(page);
 	newzone = page_zone(newpage);
 
-	xa_lock_irq(&mapping->i_pages);
-
-	pslot = radix_tree_lookup_slot(&mapping->i_pages,
- 					page_index(page));
+	xas_lock_irq(&xas);
 
 	expected_count += hpage_nr_pages(page) + page_has_private(page);
-	if (page_count(page) != expected_count ||
-		radix_tree_deref_slot_protected(pslot,
-					&mapping->i_pages.xa_lock) != page) {
-		xa_unlock_irq(&mapping->i_pages);
+	if (page_count(page) != expected_count || xas_load(&xas) != page) {
+		xas_unlock_irq(&xas);
 		return -EAGAIN;
 	}
 
 	if (!page_ref_freeze(page, expected_count)) {
-		xa_unlock_irq(&mapping->i_pages);
+		xas_unlock_irq(&xas);
 		return -EAGAIN;
 	}
 
@@ -495,7 +490,7 @@ int migrate_page_move_mapping(struct address_space *mapping,
 	if (mode == MIGRATE_ASYNC && head &&
 			!buffer_migrate_lock_buffers(head, mode)) {
 		page_ref_unfreeze(page, expected_count);
-		xa_unlock_irq(&mapping->i_pages);
+		xas_unlock_irq(&xas);
 		return -EAGAIN;
 	}
 
@@ -523,16 +518,13 @@ int migrate_page_move_mapping(struct address_space *mapping,
 		SetPageDirty(newpage);
 	}
 
-	radix_tree_replace_slot(&mapping->i_pages, pslot, newpage);
+	xas_store(&xas, newpage);
 	if (PageTransHuge(page)) {
 		int i;
-		int index = page_index(page);
 
 		for (i = 1; i < HPAGE_PMD_NR; i++) {
-			pslot = radix_tree_lookup_slot(&mapping->i_pages,
-						       index + i);
-			radix_tree_replace_slot(&mapping->i_pages, pslot,
-						newpage + i);
+			xas_next(&xas);
+			xas_store(&xas, newpage + i);
 		}
 	}
 
@@ -543,7 +535,7 @@ int migrate_page_move_mapping(struct address_space *mapping,
 	 */
 	page_ref_unfreeze(page, expected_count - hpage_nr_pages(page));
 
-	xa_unlock(&mapping->i_pages);
+	xas_unlock(&xas);
 	/* Leave irq disabled to prevent preemption while updating stats */
 
 	/*
@@ -583,22 +575,18 @@ EXPORT_SYMBOL(migrate_page_move_mapping);
 int migrate_huge_page_move_mapping(struct address_space *mapping,
 				   struct page *newpage, struct page *page)
 {
+	XA_STATE(xas, &mapping->i_pages, page_index(page));
 	int expected_count;
-	void **pslot;
-
-	xa_lock_irq(&mapping->i_pages);
-
-	pslot = radix_tree_lookup_slot(&mapping->i_pages, page_index(page));
 
+	xas_lock_irq(&xas);
 	expected_count = 2 + page_has_private(page);
-	if (page_count(page) != expected_count ||
-		radix_tree_deref_slot_protected(pslot, &mapping->i_pages.xa_lock) != page) {
-		xa_unlock_irq(&mapping->i_pages);
+	if (page_count(page) != expected_count || xas_load(&xas) != page) {
+		xas_unlock_irq(&xas);
 		return -EAGAIN;
 	}
 
 	if (!page_ref_freeze(page, expected_count)) {
-		xa_unlock_irq(&mapping->i_pages);
+		xas_unlock_irq(&xas);
 		return -EAGAIN;
 	}
 
@@ -607,11 +595,11 @@ int migrate_huge_page_move_mapping(struct address_space *mapping,
 
 	get_page(newpage);
 
-	radix_tree_replace_slot(&mapping->i_pages, pslot, newpage);
+	xas_store(&xas, newpage);
 
 	page_ref_unfreeze(page, expected_count - 1);
 
-	xa_unlock_irq(&mapping->i_pages);
+	xas_unlock_irq(&xas);
 
 	return MIGRATEPAGE_SUCCESS;
 }
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 42/74] mm: Convert huge_memory to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (40 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 41/74] mm: Convert page migration " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 43/74] mm: Convert collapse_shmem " Matthew Wilcox
                   ` (32 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Quite a straightforward conversion.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/huge_memory.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index feba371169ca..426362bea0fa 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2439,13 +2439,13 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 	ClearPageCompound(head);
 	/* See comment in __split_huge_page_tail() */
 	if (PageAnon(head)) {
-		/* Additional pin to radix tree of swap cache */
+		/* Additional pin to swap cache */
 		if (PageSwapCache(head))
 			page_ref_add(head, 2);
 		else
 			page_ref_inc(head);
 	} else {
-		/* Additional pin to radix tree */
+		/* Additional pin to page cache */
 		page_ref_add(head, 2);
 		xa_unlock(&head->mapping->i_pages);
 	}
@@ -2557,7 +2557,7 @@ bool can_split_huge_page(struct page *page, int *pextra_pins)
 {
 	int extra_pins;
 
-	/* Additional pins from radix tree */
+	/* Additional pins from page cache */
 	if (PageAnon(page))
 		extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
 	else
@@ -2653,17 +2653,14 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 	spin_lock_irqsave(zone_lru_lock(page_zone(head)), flags);
 
 	if (mapping) {
-		void **pslot;
+		XA_STATE(xas, &mapping->i_pages, page_index(head));
 
-		xa_lock(&mapping->i_pages);
-		pslot = radix_tree_lookup_slot(&mapping->i_pages,
-				page_index(head));
 		/*
-		 * Check if the head page is present in radix tree.
+		 * Check if the head page is present in page cache.
 		 * We assume all tail are present too, if head is there.
 		 */
-		if (radix_tree_deref_slot_protected(pslot,
-					&mapping->i_pages.xa_lock) != head)
+		xa_lock(&mapping->i_pages);
+		if (xas_load(&xas) != head)
 			goto fail;
 	}
 
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 43/74] mm: Convert collapse_shmem to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (41 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 42/74] mm: Convert huge_memory " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 44/74] mm: Convert khugepaged_scan_shmem " Matthew Wilcox
                   ` (31 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

I found another victim of the radix tree being hard to use.  Because
there was no call to radix_tree_preload(), khugepaged was allocating
radix_tree_nodes using GFP_ATOMIC.

I also converted a local_irq_save()/restore() pair to
disable()/enable().

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/khugepaged.c | 158 ++++++++++++++++++++----------------------------
 1 file changed, 65 insertions(+), 93 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index d6992ba1f604..43598cc5998b 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1287,17 +1287,17 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
  *
  * Basic scheme is simple, details are more complex:
  *  - allocate and freeze a new huge page;
- *  - scan over radix tree replacing old pages the new one
+ *  - scan page cache replacing old pages with the new one
  *    + swap in pages if necessary;
  *    + fill in gaps;
- *    + keep old pages around in case if rollback is required;
- *  - if replacing succeed:
+ *    + keep old pages around in case rollback is required;
+ *  - if replacing succeeds:
  *    + copy data over;
  *    + free old pages;
  *    + unfreeze huge page;
  *  - if replacing failed;
  *    + put all pages back and unfreeze them;
- *    + restore gaps in the radix-tree;
+ *    + restore gaps in the page cache;
  *    + free huge page;
  */
 static void collapse_shmem(struct mm_struct *mm,
@@ -1305,12 +1305,11 @@ static void collapse_shmem(struct mm_struct *mm,
 		struct page **hpage, int node)
 {
 	gfp_t gfp;
-	struct page *page, *new_page, *tmp;
+	struct page *new_page;
 	struct mem_cgroup *memcg;
 	pgoff_t index, end = start + HPAGE_PMD_NR;
 	LIST_HEAD(pagelist);
-	struct radix_tree_iter iter;
-	void **slot;
+	XA_STATE(xas, &mapping->i_pages, start);
 	int nr_none = 0, result = SCAN_SUCCEED;
 
 	VM_BUG_ON(start & (HPAGE_PMD_NR - 1));
@@ -1335,48 +1334,48 @@ static void collapse_shmem(struct mm_struct *mm,
 	__SetPageLocked(new_page);
 	BUG_ON(!page_ref_freeze(new_page, 1));
 
-
 	/*
-	 * At this point the new_page is 'frozen' (page_count() is zero), locked
-	 * and not up-to-date. It's safe to insert it into radix tree, because
-	 * nobody would be able to map it or use it in other way until we
-	 * unfreeze it.
+	 * At this point the new_page is 'frozen' (page_count() is zero),
+	 * locked and not up-to-date. It's safe to insert it into the page
+	 * cache, because nobody would be able to map it or use it in other
+	 * way until we unfreeze it.
 	 */
 
-	index = start;
-	xa_lock_irq(&mapping->i_pages);
-	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
-		int n = min(iter.index, end) - index;
-
-		/*
-		 * Handle holes in the radix tree: charge it from shmem and
-		 * insert relevant subpage of new_page into the radix-tree.
-		 */
-		if (n && !shmem_charge(mapping->host, n)) {
-			result = SCAN_FAIL;
+	/* This will be less messy when we use multi-index entries */
+	do {
+		xas_lock_irq(&xas);
+		xas_create_range(&xas, end - 1);
+		if (!xas_error(&xas))
 			break;
-		}
-		nr_none += n;
-		for (; index < min(iter.index, end); index++) {
-			radix_tree_insert(&mapping->i_pages, index,
-					new_page + (index % HPAGE_PMD_NR));
-		}
+		xas_unlock_irq(&xas);
+		if (!xas_nomem(&xas, GFP_KERNEL))
+			goto out;
+	} while (1);
 
-		/* We are done. */
-		if (index >= end)
-			break;
+	for (index = start; index < end; index++) {
+		struct page *page = xas_next(&xas);
+
+		VM_BUG_ON(index != xas.xa_index);
+		if (!page) {
+			if (!shmem_charge(mapping->host, 1)) {
+				result = SCAN_FAIL;
+				break;
+			}
+			xas_store(&xas, new_page + (index % HPAGE_PMD_NR));
+			nr_none++;
+			continue;
+		}
 
-		page = radix_tree_deref_slot_protected(slot,
-				&mapping->i_pages.xa_lock);
 		if (xa_is_value(page) || !PageUptodate(page)) {
-			xa_unlock_irq(&mapping->i_pages);
+			xas_unlock_irq(&xas);
 			/* swap in or instantiate fallocated page */
 			if (shmem_getpage(mapping->host, index, &page,
 						SGP_NOHUGE)) {
 				result = SCAN_FAIL;
-				goto tree_unlocked;
+				goto xa_unlocked;
 			}
-			xa_lock_irq(&mapping->i_pages);
+			xas_lock_irq(&xas);
+			xas_set(&xas, index);
 		} else if (trylock_page(page)) {
 			get_page(page);
 		} else {
@@ -1396,7 +1395,7 @@ static void collapse_shmem(struct mm_struct *mm,
 			result = SCAN_TRUNCATED;
 			goto out_unlock;
 		}
-		xa_unlock_irq(&mapping->i_pages);
+		xas_unlock_irq(&xas);
 
 		if (isolate_lru_page(page)) {
 			result = SCAN_DEL_PAGE_LRU;
@@ -1406,17 +1405,16 @@ static void collapse_shmem(struct mm_struct *mm,
 		if (page_mapped(page))
 			unmap_mapping_pages(mapping, index, 1, false);
 
-		xa_lock_irq(&mapping->i_pages);
+		xas_lock(&xas);
+		xas_set(&xas, index);
 
-		slot = radix_tree_lookup_slot(&mapping->i_pages, index);
-		VM_BUG_ON_PAGE(page != radix_tree_deref_slot_protected(slot,
-					&mapping->i_pages.xa_lock), page);
+		VM_BUG_ON_PAGE(page != xas_load(&xas), page);
 		VM_BUG_ON_PAGE(page_mapped(page), page);
 
 		/*
 		 * The page is expected to have page_count() == 3:
 		 *  - we hold a pin on it;
-		 *  - one reference from radix tree;
+		 *  - one reference from page cache;
 		 *  - one from isolate_lru_page;
 		 */
 		if (!page_ref_freeze(page, 3)) {
@@ -1431,56 +1429,30 @@ static void collapse_shmem(struct mm_struct *mm,
 		list_add_tail(&page->lru, &pagelist);
 
 		/* Finally, replace with the new page. */
-		radix_tree_replace_slot(&mapping->i_pages, slot,
-				new_page + (index % HPAGE_PMD_NR));
-
-		slot = radix_tree_iter_resume(slot, &iter);
-		index++;
+		xas_store(&xas, new_page + (index % HPAGE_PMD_NR));
 		continue;
 out_lru:
-		xa_unlock_irq(&mapping->i_pages);
+		xas_unlock_irq(&xas);
 		putback_lru_page(page);
 out_isolate_failed:
 		unlock_page(page);
 		put_page(page);
-		goto tree_unlocked;
+		goto xa_unlocked;
 out_unlock:
 		unlock_page(page);
 		put_page(page);
 		break;
 	}
+	xas_unlock_irq(&xas);
 
-	/*
-	 * Handle hole in radix tree at the end of the range.
-	 * This code only triggers if there's nothing in radix tree
-	 * beyond 'end'.
-	 */
-	if (result == SCAN_SUCCEED && index < end) {
-		int n = end - index;
-
-		if (!shmem_charge(mapping->host, n)) {
-			result = SCAN_FAIL;
-			goto tree_locked;
-		}
-
-		for (; index < end; index++) {
-			radix_tree_insert(&mapping->i_pages, index,
-					new_page + (index % HPAGE_PMD_NR));
-		}
-		nr_none += n;
-	}
-
-tree_locked:
-	xa_unlock_irq(&mapping->i_pages);
-tree_unlocked:
-
+xa_unlocked:
 	if (result == SCAN_SUCCEED) {
-		unsigned long flags;
+		struct page *page, *tmp;
 		struct zone *zone = page_zone(new_page);
 
 		/*
-		 * Replacing old pages with new one has succeed, now we need to
-		 * copy the content and free old pages.
+		 * Replacing old pages with new one has succeeded, now we
+		 * need to copy the content and free the old pages.
 		 */
 		list_for_each_entry_safe(page, tmp, &pagelist, lru) {
 			copy_highpage(new_page + (page->index % HPAGE_PMD_NR),
@@ -1494,16 +1466,16 @@ static void collapse_shmem(struct mm_struct *mm,
 			put_page(page);
 		}
 
-		local_irq_save(flags);
+		local_irq_disable();
 		__inc_node_page_state(new_page, NR_SHMEM_THPS);
 		if (nr_none) {
 			__mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none);
 			__mod_node_page_state(zone->zone_pgdat, NR_SHMEM, nr_none);
 		}
-		local_irq_restore(flags);
+		local_irq_enable();
 
 		/*
-		 * Remove pte page tables, so we can re-faulti
+		 * Remove pte page tables, so we can re-fault
 		 * the page as huge.
 		 */
 		retract_page_tables(mapping, start);
@@ -1518,37 +1490,37 @@ static void collapse_shmem(struct mm_struct *mm,
 
 		*hpage = NULL;
 	} else {
-		/* Something went wrong: rollback changes to the radix-tree */
+		struct page *page;
+		/* Something went wrong: roll back page cache changes */
 		shmem_uncharge(mapping->host, nr_none);
-		xa_lock_irq(&mapping->i_pages);
-		radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
-			if (iter.index >= end)
-				break;
+		xas_lock_irq(&xas);
+		xas_set(&xas, start);
+		xas_for_each(&xas, page, end - 1) {
 			page = list_first_entry_or_null(&pagelist,
 					struct page, lru);
-			if (!page || iter.index < page->index) {
+			if (!page || xas.xa_index < page->index) {
 				if (!nr_none)
 					break;
 				nr_none--;
 				/* Put holes back where they were */
-				radix_tree_delete(&mapping->i_pages, iter.index);
+				xas_store(&xas, NULL);
 				continue;
 			}
 
-			VM_BUG_ON_PAGE(page->index != iter.index, page);
+			VM_BUG_ON_PAGE(page->index != xas.xa_index, page);
 
 			/* Unfreeze the page. */
 			list_del(&page->lru);
 			page_ref_unfreeze(page, 2);
-			radix_tree_replace_slot(&mapping->i_pages, slot, page);
-			slot = radix_tree_iter_resume(slot, &iter);
-			xa_unlock_irq(&mapping->i_pages);
+			xas_store(&xas, page);
+			xas_pause(&xas);
+			xas_unlock_irq(&xas);
 			putback_lru_page(page);
 			unlock_page(page);
-			xa_lock_irq(&mapping->i_pages);
+			xas_lock_irq(&xas);
 		}
 		VM_BUG_ON(nr_none);
-		xa_unlock_irq(&mapping->i_pages);
+		xas_unlock_irq(&xas);
 
 		/* Unfreeze new_page, caller would take care about freeing it */
 		page_ref_unfreeze(new_page, 1);
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 44/74] mm: Convert khugepaged_scan_shmem to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (42 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 43/74] mm: Convert collapse_shmem " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 45/74] mm: Convert is_page_cache_freeable " Matthew Wilcox
                   ` (30 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Slightly shorter and easier to read code.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/khugepaged.c | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 43598cc5998b..28579ad0c5fe 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1538,8 +1538,7 @@ static void khugepaged_scan_shmem(struct mm_struct *mm,
 		pgoff_t start, struct page **hpage)
 {
 	struct page *page = NULL;
-	struct radix_tree_iter iter;
-	void **slot;
+	XA_STATE(xas, &mapping->i_pages, start);
 	int present, swap;
 	int node = NUMA_NO_NODE;
 	int result = SCAN_SUCCEED;
@@ -1548,17 +1547,11 @@ static void khugepaged_scan_shmem(struct mm_struct *mm,
 	swap = 0;
 	memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
 	rcu_read_lock();
-	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
-		if (iter.index >= start + HPAGE_PMD_NR)
-			break;
-
-		page = radix_tree_deref_slot(slot);
-		if (radix_tree_deref_retry(page)) {
-			slot = radix_tree_iter_retry(&iter);
+	xas_for_each(&xas, page, start + HPAGE_PMD_NR - 1) {
+		if (xas_retry(&xas, page))
 			continue;
-		}
 
-		if (radix_tree_exception(page)) {
+		if (xa_is_value(page)) {
 			if (++swap > khugepaged_max_ptes_swap) {
 				result = SCAN_EXCEED_SWAP_PTE;
 				break;
@@ -1597,7 +1590,7 @@ static void khugepaged_scan_shmem(struct mm_struct *mm,
 		present++;
 
 		if (need_resched()) {
-			slot = radix_tree_iter_resume(slot, &iter);
+			xas_pause(&xas);
 			cond_resched_rcu();
 		}
 	}
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 45/74] mm: Convert is_page_cache_freeable to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (43 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 44/74] mm: Convert khugepaged_scan_shmem " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 46/74] pagevec: Use xa_tag_t Matthew Wilcox
                   ` (29 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

This is just a variable rename and comment change.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/vmscan.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 0448b1b366d9..575747728ee6 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -572,12 +572,12 @@ static inline int is_page_cache_freeable(struct page *page)
 {
 	/*
 	 * A freeable page cache page is referenced only by the caller
-	 * that isolated the page, the page cache radix tree and
-	 * optional buffer heads at page->private.
+	 * that isolated the page, the page cache and optional buffer
+	 * heads at page->private.
 	 */
-	int radix_pins = PageTransHuge(page) && PageSwapCache(page) ?
+	int page_cache_pins = PageTransHuge(page) && PageSwapCache(page) ?
 		HPAGE_PMD_NR : 1;
-	return page_count(page) - page_has_private(page) == 1 + radix_pins;
+	return page_count(page) - page_has_private(page) == 1 + page_cache_pins;
 }
 
 static int may_write_to_inode(struct inode *inode, struct scan_control *sc)
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 46/74] pagevec: Use xa_tag_t
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (44 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 45/74] mm: Convert is_page_cache_freeable " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 47/74] shmem: Convert shmem_radix_tree_replace to XArray Matthew Wilcox
                   ` (28 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Removes sparse warnings.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 fs/btrfs/extent_io.c    | 4 ++--
 fs/ext4/inode.c         | 2 +-
 fs/f2fs/data.c          | 2 +-
 fs/gfs2/aops.c          | 2 +-
 include/linux/pagevec.h | 8 +++++---
 mm/swap.c               | 4 ++--
 6 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index cce6087d6880..ac105d97dd81 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3792,7 +3792,7 @@ int btree_write_cache_pages(struct address_space *mapping,
 	pgoff_t index;
 	pgoff_t end;		/* Inclusive */
 	int scanned = 0;
-	int tag;
+	xa_tag_t tag;
 
 	pagevec_init(&pvec);
 	if (wbc->range_cyclic) {
@@ -3917,7 +3917,7 @@ static int extent_write_cache_pages(struct address_space *mapping,
 	pgoff_t done_index;
 	int range_whole = 0;
 	int scanned = 0;
-	int tag;
+	xa_tag_t tag;
 
 	/*
 	 * We have to hold onto the inode so that ordered extents can do their
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 38214c05f204..e6c433527dce 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2615,7 +2615,7 @@ static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
 	long left = mpd->wbc->nr_to_write;
 	pgoff_t index = mpd->first_page;
 	pgoff_t end = mpd->last_page;
-	int tag;
+	xa_tag_t tag;
 	int i, err = 0;
 	int blkbits = mpd->inode->i_blkbits;
 	ext4_lblk_t lblk;
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 8f931d699287..e5c0b1e74ce6 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1942,7 +1942,7 @@ static int f2fs_write_cache_pages(struct address_space *mapping,
 	pgoff_t last_idx = ULONG_MAX;
 	int cycled;
 	int range_whole = 0;
-	int tag;
+	xa_tag_t tag;
 
 	pagevec_init(&pvec);
 
diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
index 35f5ee23566d..b8609bb1e2e0 100644
--- a/fs/gfs2/aops.c
+++ b/fs/gfs2/aops.c
@@ -370,7 +370,7 @@ static int gfs2_write_cache_jdata(struct address_space *mapping,
 	pgoff_t done_index;
 	int cycled;
 	int range_whole = 0;
-	int tag;
+	xa_tag_t tag;
 
 	pagevec_init(&pvec);
 	if (wbc->range_cyclic) {
diff --git a/include/linux/pagevec.h b/include/linux/pagevec.h
index 6dc456ac6136..955bd6425903 100644
--- a/include/linux/pagevec.h
+++ b/include/linux/pagevec.h
@@ -9,6 +9,8 @@
 #ifndef _LINUX_PAGEVEC_H
 #define _LINUX_PAGEVEC_H
 
+#include <linux/xarray.h>
+
 /* 15 pointers + header align the pagevec structure to a power of two */
 #define PAGEVEC_SIZE	15
 
@@ -40,12 +42,12 @@ static inline unsigned pagevec_lookup(struct pagevec *pvec,
 
 unsigned pagevec_lookup_range_tag(struct pagevec *pvec,
 		struct address_space *mapping, pgoff_t *index, pgoff_t end,
-		int tag);
+		xa_tag_t tag);
 unsigned pagevec_lookup_range_nr_tag(struct pagevec *pvec,
 		struct address_space *mapping, pgoff_t *index, pgoff_t end,
-		int tag, unsigned max_pages);
+		xa_tag_t tag, unsigned max_pages);
 static inline unsigned pagevec_lookup_tag(struct pagevec *pvec,
-		struct address_space *mapping, pgoff_t *index, int tag)
+		struct address_space *mapping, pgoff_t *index, xa_tag_t tag)
 {
 	return pagevec_lookup_range_tag(pvec, mapping, index, (pgoff_t)-1, tag);
 }
diff --git a/mm/swap.c b/mm/swap.c
index 4c5c7fcc6e46..a7ff602213a9 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -1002,7 +1002,7 @@ EXPORT_SYMBOL(pagevec_lookup_range);
 
 unsigned pagevec_lookup_range_tag(struct pagevec *pvec,
 		struct address_space *mapping, pgoff_t *index, pgoff_t end,
-		int tag)
+		xa_tag_t tag)
 {
 	pvec->nr = find_get_pages_range_tag(mapping, index, end, tag,
 					PAGEVEC_SIZE, pvec->pages);
@@ -1012,7 +1012,7 @@ EXPORT_SYMBOL(pagevec_lookup_range_tag);
 
 unsigned pagevec_lookup_range_nr_tag(struct pagevec *pvec,
 		struct address_space *mapping, pgoff_t *index, pgoff_t end,
-		int tag, unsigned max_pages)
+		xa_tag_t tag, unsigned max_pages)
 {
 	pvec->nr = find_get_pages_range_tag(mapping, index, end, tag,
 		min_t(unsigned int, max_pages, PAGEVEC_SIZE), pvec->pages);
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 47/74] shmem: Convert shmem_radix_tree_replace to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (45 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 46/74] pagevec: Use xa_tag_t Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 48/74] shmem: Convert shmem_confirm_swap " Matthew Wilcox
                   ` (27 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Rename shmem_radix_tree_replace() to shmem_replace_entry() and
convert it to use the XArray API.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/shmem.c | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 3b03ede3515c..2b8720d32e7a 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -321,24 +321,20 @@ void shmem_uncharge(struct inode *inode, long pages)
 }
 
 /*
- * Replace item expected in radix tree by a new item, while holding tree lock.
+ * Replace item expected in xarray by a new item, while holding xa_lock.
  */
-static int shmem_radix_tree_replace(struct address_space *mapping,
+static int shmem_replace_entry(struct address_space *mapping,
 			pgoff_t index, void *expected, void *replacement)
 {
-	struct radix_tree_node *node;
-	void __rcu **pslot;
+	XA_STATE(xas, &mapping->i_pages, index);
 	void *item;
 
 	VM_BUG_ON(!expected);
 	VM_BUG_ON(!replacement);
-	item = __radix_tree_lookup(&mapping->i_pages, index, &node, &pslot);
-	if (!item)
-		return -ENOENT;
+	item = xas_load(&xas);
 	if (item != expected)
 		return -ENOENT;
-	__radix_tree_replace(&mapping->i_pages, node, pslot,
-			     replacement, NULL);
+	xas_store(&xas, replacement);
 	return 0;
 }
 
@@ -623,8 +619,7 @@ static int shmem_add_to_page_cache(struct page *page,
 	} else if (!expected) {
 		error = radix_tree_insert(&mapping->i_pages, index, page);
 	} else {
-		error = shmem_radix_tree_replace(mapping, index, expected,
-								 page);
+		error = shmem_replace_entry(mapping, index, expected, page);
 	}
 
 	if (!error) {
@@ -653,7 +648,7 @@ static void shmem_delete_from_page_cache(struct page *page, void *radswap)
 	VM_BUG_ON_PAGE(PageCompound(page), page);
 
 	xa_lock_irq(&mapping->i_pages);
-	error = shmem_radix_tree_replace(mapping, page->index, page, radswap);
+	error = shmem_replace_entry(mapping, page->index, page, radswap);
 	page->mapping = NULL;
 	mapping->nrpages--;
 	__dec_node_page_state(page, NR_FILE_PAGES);
@@ -1577,8 +1572,7 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp,
 	 * a nice clean interface for us to replace oldpage by newpage there.
 	 */
 	xa_lock_irq(&swap_mapping->i_pages);
-	error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage,
-								   newpage);
+	error = shmem_replace_entry(swap_mapping, swap_index, oldpage, newpage);
 	if (!error) {
 		__inc_node_page_state(newpage, NR_FILE_PAGES);
 		__dec_node_page_state(oldpage, NR_FILE_PAGES);
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 48/74] shmem: Convert shmem_confirm_swap to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (46 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 47/74] shmem: Convert shmem_radix_tree_replace to XArray Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 49/74] shmem: Convert find_swap_entry " Matthew Wilcox
                   ` (26 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

xa_load has its own RCU locking, so we can eliminate it here.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/shmem.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 2b8720d32e7a..479e4a8e6d68 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -348,12 +348,7 @@ static int shmem_replace_entry(struct address_space *mapping,
 static bool shmem_confirm_swap(struct address_space *mapping,
 			       pgoff_t index, swp_entry_t swap)
 {
-	void *item;
-
-	rcu_read_lock();
-	item = radix_tree_lookup(&mapping->i_pages, index);
-	rcu_read_unlock();
-	return item == swp_to_radix_entry(swap);
+	return xa_load(&mapping->i_pages, index) == swp_to_radix_entry(swap);
 }
 
 /*
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 49/74] shmem: Convert find_swap_entry to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (47 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 48/74] shmem: Convert shmem_confirm_swap " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 50/74] shmem: Convert shmem_add_to_page_cache " Matthew Wilcox
                   ` (25 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

This is a 1:1 conversion.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/shmem.c | 27 ++++++++++-----------------
 1 file changed, 10 insertions(+), 17 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 479e4a8e6d68..983a27656e2e 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1099,34 +1099,27 @@ static void shmem_evict_inode(struct inode *inode)
 	clear_inode(inode);
 }
 
-static unsigned long find_swap_entry(struct radix_tree_root *root, void *item)
+static unsigned long find_swap_entry(struct xarray *xa, void *item)
 {
-	struct radix_tree_iter iter;
-	void __rcu **slot;
-	unsigned long found = -1;
+	XA_STATE(xas, xa, 0);
 	unsigned int checked = 0;
+	void *entry;
 
 	rcu_read_lock();
-	radix_tree_for_each_slot(slot, root, &iter, 0) {
-		void *entry = radix_tree_deref_slot(slot);
-
-		if (radix_tree_deref_retry(entry)) {
-			slot = radix_tree_iter_retry(&iter);
+	xas_for_each(&xas, entry, ULONG_MAX) {
+		if (xas_retry(&xas, entry))
 			continue;
-		}
-		if (entry == item) {
-			found = iter.index;
+		if (entry == item)
 			break;
-		}
 		checked++;
-		if ((checked % 4096) != 0)
+		if ((checked % XA_CHECK_SCHED) != 0)
 			continue;
-		slot = radix_tree_iter_resume(slot, &iter);
+		xas_pause(&xas);
 		cond_resched_rcu();
 	}
-
 	rcu_read_unlock();
-	return found;
+
+	return xas_invalid(&xas) ? -1 : xas.xa_index;
 }
 
 /*
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 50/74] shmem: Convert shmem_add_to_page_cache to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (48 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 49/74] shmem: Convert find_swap_entry " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 51/74] shmem: Convert shmem_alloc_hugepage " Matthew Wilcox
                   ` (24 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

This removes the last caller of radix_tree_maybe_preload_order().
Simpler code, unless we run out of memory for new xa_nodes partway through
inserting entries into the xarray.  Hopefully we can support multi-index
entries in the page cache soon and all the awful code goes away.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/shmem.c | 87 ++++++++++++++++++++++++------------------------------
 1 file changed, 39 insertions(+), 48 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 983a27656e2e..8e702b6d84a5 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -576,9 +576,10 @@ static inline bool is_huge_enabled(struct shmem_sb_info *sbinfo)
  */
 static int shmem_add_to_page_cache(struct page *page,
 				   struct address_space *mapping,
-				   pgoff_t index, void *expected)
+				   pgoff_t index, void *expected, gfp_t gfp)
 {
-	int error, nr = hpage_nr_pages(page);
+	XA_STATE(xas, &mapping->i_pages, index);
+	unsigned long i, nr = 1UL << compound_order(page);
 
 	VM_BUG_ON_PAGE(PageTail(page), page);
 	VM_BUG_ON_PAGE(index != round_down(index, nr), page);
@@ -587,49 +588,47 @@ static int shmem_add_to_page_cache(struct page *page,
 	VM_BUG_ON(expected && PageTransHuge(page));
 
 	page_ref_add(page, nr);
-	page->mapping = mapping;
 	page->index = index;
+	page->mapping = mapping;
 
-	xa_lock_irq(&mapping->i_pages);
-	if (PageTransHuge(page)) {
-		void __rcu **results;
-		pgoff_t idx;
-		int i;
-
-		error = 0;
-		if (radix_tree_gang_lookup_slot(&mapping->i_pages,
-					&results, &idx, index, 1) &&
-				idx < index + HPAGE_PMD_NR) {
-			error = -EEXIST;
+	do {
+		xas_lock_irq(&xas);
+		xas_create_range(&xas, index + nr - 1);
+		if (xas_error(&xas))
+			goto unlock;
+		for (i = 0; i < nr; i++) {
+			void *entry = xas_load(&xas);
+			if (entry != expected)
+				xas_set_err(&xas, -ENOENT);
+			if (xas_error(&xas))
+				goto undo;
+			xas_store(&xas, page + i);
+			xas_next(&xas);
 		}
-
-		if (!error) {
-			for (i = 0; i < HPAGE_PMD_NR; i++) {
-				error = radix_tree_insert(&mapping->i_pages,
-						index + i, page + i);
-				VM_BUG_ON(error);
-			}
+		if (PageTransHuge(page)) {
 			count_vm_event(THP_FILE_ALLOC);
+			__inc_node_page_state(page, NR_SHMEM_THPS);
 		}
-	} else if (!expected) {
-		error = radix_tree_insert(&mapping->i_pages, index, page);
-	} else {
-		error = shmem_replace_entry(mapping, index, expected, page);
-	}
-
-	if (!error) {
 		mapping->nrpages += nr;
-		if (PageTransHuge(page))
-			__inc_node_page_state(page, NR_SHMEM_THPS);
 		__mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr);
 		__mod_node_page_state(page_pgdat(page), NR_SHMEM, nr);
-		xa_unlock_irq(&mapping->i_pages);
-	} else {
+		goto unlock;
+undo:
+		while (i-- > 0) {
+			xas_store(&xas, NULL);
+			xas_prev(&xas);
+		}
+unlock:
+		xas_unlock_irq(&xas);
+	} while (xas_nomem(&xas, gfp));
+
+	if (xas_error(&xas)) {
 		page->mapping = NULL;
-		xa_unlock_irq(&mapping->i_pages);
 		page_ref_sub(page, nr);
+		return xas_error(&xas);
 	}
-	return error;
+
+	return 0;
 }
 
 /*
@@ -1182,7 +1181,7 @@ static int shmem_unuse_inode(struct shmem_inode_info *info,
 	 */
 	if (!error)
 		error = shmem_add_to_page_cache(*pagep, mapping, index,
-						radswap);
+						radswap, gfp);
 	if (error != -ENOMEM) {
 		/*
 		 * Truncation and eviction use free_swap_and_cache(), which
@@ -1698,7 +1697,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
 				false);
 		if (!error) {
 			error = shmem_add_to_page_cache(page, mapping, index,
-						swp_to_radix_entry(swap));
+						swp_to_radix_entry(swap), gfp);
 			/*
 			 * We already confirmed swap under page lock, and make
 			 * no memory allocation here, so usually no possibility
@@ -1804,13 +1803,8 @@ alloc_nohuge:		page = shmem_alloc_and_acct_page(gfp, inode,
 				PageTransHuge(page));
 		if (error)
 			goto unacct;
-		error = radix_tree_maybe_preload_order(gfp & GFP_RECLAIM_MASK,
-				compound_order(page));
-		if (!error) {
-			error = shmem_add_to_page_cache(page, mapping, hindex,
-							NULL);
-			radix_tree_preload_end();
-		}
+		error = shmem_add_to_page_cache(page, mapping, hindex,
+						NULL, gfp & GFP_RECLAIM_MASK);
 		if (error) {
 			mem_cgroup_cancel_charge(page, memcg,
 					PageTransHuge(page));
@@ -2277,11 +2271,8 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
 	if (ret)
 		goto out_release;
 
-	ret = radix_tree_maybe_preload(gfp & GFP_RECLAIM_MASK);
-	if (!ret) {
-		ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL);
-		radix_tree_preload_end();
-	}
+	ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL,
+						gfp & GFP_RECLAIM_MASK);
 	if (ret)
 		goto out_release_uncharge;
 
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 51/74] shmem: Convert shmem_alloc_hugepage to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (49 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 50/74] shmem: Convert shmem_add_to_page_cache " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 52/74] shmem: Convert shmem_free_swap " Matthew Wilcox
                   ` (23 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

xa_find() is a slightly easier API to use than
radix_tree_gang_lookup_slot() because it contains its own RCU locking.
This commit removes the last user of radix_tree_gang_lookup_slot()
so remove the function too.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/radix-tree.h |  6 +-----
 lib/radix-tree.c           | 44 +-------------------------------------
 mm/shmem.c                 | 14 ++++--------
 3 files changed, 6 insertions(+), 58 deletions(-)

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index eefa0b099dd5..081e68b4376b 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -147,12 +147,11 @@ static inline unsigned int iter_shift(const struct radix_tree_iter *iter)
  * radix_tree_lookup_slot
  * radix_tree_tag_get
  * radix_tree_gang_lookup
- * radix_tree_gang_lookup_slot
  * radix_tree_gang_lookup_tag
  * radix_tree_gang_lookup_tag_slot
  * radix_tree_tagged
  *
- * The first 8 functions are able to be called locklessly, using RCU. The
+ * The first 7 functions are able to be called locklessly, using RCU. The
  * caller must ensure calls to these functions are made within rcu_read_lock()
  * regions. Other readers (lock-free or otherwise) and modifications may be
  * running concurrently.
@@ -263,9 +262,6 @@ void radix_tree_clear_tags(struct radix_tree_root *, struct radix_tree_node *,
 unsigned int radix_tree_gang_lookup(const struct radix_tree_root *,
 			void **results, unsigned long first_index,
 			unsigned int max_items);
-unsigned int radix_tree_gang_lookup_slot(const struct radix_tree_root *,
-			void __rcu ***results, unsigned long *indices,
-			unsigned long first_index, unsigned int max_items);
 int radix_tree_preload(gfp_t gfp_mask);
 int radix_tree_maybe_preload(gfp_t gfp_mask);
 int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order);
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 5c8a262f506c..d0f44ea96945 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -1138,7 +1138,7 @@ void __radix_tree_replace(struct radix_tree_root *root,
  * @slot:	pointer to slot
  * @item:	new item to store in the slot.
  *
- * For use with radix_tree_lookup_slot(), radix_tree_gang_lookup_slot(),
+ * For use with radix_tree_lookup_slot() and
  * radix_tree_gang_lookup_tag_slot().  Caller must hold tree write locked
  * across slot lookup and replacement.
  *
@@ -1772,48 +1772,6 @@ radix_tree_gang_lookup(const struct radix_tree_root *root, void **results,
 }
 EXPORT_SYMBOL(radix_tree_gang_lookup);
 
-/**
- *	radix_tree_gang_lookup_slot - perform multiple slot lookup on radix tree
- *	@root:		radix tree root
- *	@results:	where the results of the lookup are placed
- *	@indices:	where their indices should be placed (but usually NULL)
- *	@first_index:	start the lookup from this key
- *	@max_items:	place up to this many items at *results
- *
- *	Performs an index-ascending scan of the tree for present items.  Places
- *	their slots at *@results and returns the number of items which were
- *	placed at *@results.
- *
- *	The implementation is naive.
- *
- *	Like radix_tree_gang_lookup as far as RCU and locking goes. Slots must
- *	be dereferenced with radix_tree_deref_slot, and if using only RCU
- *	protection, radix_tree_deref_slot may fail requiring a retry.
- */
-unsigned int
-radix_tree_gang_lookup_slot(const struct radix_tree_root *root,
-			void __rcu ***results, unsigned long *indices,
-			unsigned long first_index, unsigned int max_items)
-{
-	struct radix_tree_iter iter;
-	void __rcu **slot;
-	unsigned int ret = 0;
-
-	if (unlikely(!max_items))
-		return 0;
-
-	radix_tree_for_each_slot(slot, root, &iter, first_index) {
-		results[ret] = slot;
-		if (indices)
-			indices[ret] = iter.index;
-		if (++ret == max_items)
-			break;
-	}
-
-	return ret;
-}
-EXPORT_SYMBOL(radix_tree_gang_lookup_slot);
-
 /**
  *	radix_tree_gang_lookup_tag - perform multiple lookup on a radix tree
  *	                             based on a tag
diff --git a/mm/shmem.c b/mm/shmem.c
index 8e702b6d84a5..09452ca79220 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1434,23 +1434,17 @@ static struct page *shmem_alloc_hugepage(gfp_t gfp,
 		struct shmem_inode_info *info, pgoff_t index)
 {
 	struct vm_area_struct pvma;
-	struct inode *inode = &info->vfs_inode;
-	struct address_space *mapping = inode->i_mapping;
-	pgoff_t idx, hindex;
-	void __rcu **results;
+	struct address_space *mapping = info->vfs_inode.i_mapping;
+	pgoff_t hindex;
 	struct page *page;
 
 	if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
 		return NULL;
 
 	hindex = round_down(index, HPAGE_PMD_NR);
-	rcu_read_lock();
-	if (radix_tree_gang_lookup_slot(&mapping->i_pages, &results, &idx,
-				hindex, 1) && idx < hindex + HPAGE_PMD_NR) {
-		rcu_read_unlock();
+	if (xa_find(&mapping->i_pages, &hindex, hindex + HPAGE_PMD_NR - 1,
+								XA_PRESENT))
 		return NULL;
-	}
-	rcu_read_unlock();
 
 	shmem_pseudo_vma_init(&pvma, info, hindex);
 	page = alloc_pages_vma(gfp | __GFP_COMP | __GFP_NORETRY | __GFP_NOWARN,
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 52/74] shmem: Convert shmem_free_swap to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (50 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 51/74] shmem: Convert shmem_alloc_hugepage " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 53/74] shmem: Convert shmem_partial_swap_usage " Matthew Wilcox
                   ` (22 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Since we are conditionally storing NULL in the XArray, we do not need
to allocate memory and the GFP flags will be unused.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/shmem.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 09452ca79220..9dbbdd5dee30 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -653,7 +653,7 @@ static void shmem_delete_from_page_cache(struct page *page, void *radswap)
 }
 
 /*
- * Remove swap entry from radix tree, free the swap and its page cache.
+ * Remove swap entry from page cache, free the swap and its page cache.
  */
 static int shmem_free_swap(struct address_space *mapping,
 			   pgoff_t index, void *radswap)
@@ -661,7 +661,7 @@ static int shmem_free_swap(struct address_space *mapping,
 	void *old;
 
 	xa_lock_irq(&mapping->i_pages);
-	old = radix_tree_delete_item(&mapping->i_pages, index, radswap);
+	old = __xa_cmpxchg(&mapping->i_pages, index, radswap, NULL, 0);
 	xa_unlock_irq(&mapping->i_pages);
 	if (old != radswap)
 		return -ENOENT;
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 53/74] shmem: Convert shmem_partial_swap_usage to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (51 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 52/74] shmem: Convert shmem_free_swap " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 54/74] memfd: Convert memfd_wait_for_pins " Matthew Wilcox
                   ` (21 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Simpler code because the xarray takes care of things like the limit and
dereferencing the slot.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/shmem.c | 18 ++++--------------
 1 file changed, 4 insertions(+), 14 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index 9dbbdd5dee30..bffb87854852 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -679,29 +679,19 @@ static int shmem_free_swap(struct address_space *mapping,
 unsigned long shmem_partial_swap_usage(struct address_space *mapping,
 						pgoff_t start, pgoff_t end)
 {
-	struct radix_tree_iter iter;
-	void __rcu **slot;
+	XA_STATE(xas, &mapping->i_pages, start);
 	struct page *page;
 	unsigned long swapped = 0;
 
 	rcu_read_lock();
-
-	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
-		if (iter.index >= end)
-			break;
-
-		page = radix_tree_deref_slot(slot);
-
-		if (radix_tree_deref_retry(page)) {
-			slot = radix_tree_iter_retry(&iter);
+	xas_for_each(&xas, page, end - 1) {
+		if (xas_retry(&xas, page))
 			continue;
-		}
-
 		if (xa_is_value(page))
 			swapped++;
 
 		if (need_resched()) {
-			slot = radix_tree_iter_resume(slot, &iter);
+			xas_pause(&xas);
 			cond_resched_rcu();
 		}
 	}
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 54/74] memfd: Convert memfd_wait_for_pins to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (52 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 53/74] shmem: Convert shmem_partial_swap_usage " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 55/74] memfd: Convert memfd_tag_pins " Matthew Wilcox
                   ` (20 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Simplify the locking by taking the spinlock while we walk the tree on
the assumption that many acquires and releases of the lock will be worse
than holding the lock while we process an entire batch of pages.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
---
 mm/memfd.c | 61 ++++++++++++++++++++++--------------------------------
 1 file changed, 25 insertions(+), 36 deletions(-)

diff --git a/mm/memfd.c b/mm/memfd.c
index 27069518e3c5..e7d6be725b7a 100644
--- a/mm/memfd.c
+++ b/mm/memfd.c
@@ -21,7 +21,7 @@
 #include <uapi/linux/memfd.h>
 
 /*
- * We need a tag: a new tag would expand every radix_tree_node by 8 bytes,
+ * We need a tag: a new tag would expand every xa_node by 8 bytes,
  * so reuse a tag which we firmly believe is never set or cleared on tmpfs
  * or hugetlbfs because they are memory only filesystems.
  */
@@ -72,9 +72,7 @@ static void memfd_tag_pins(struct address_space *mapping)
  */
 static int memfd_wait_for_pins(struct address_space *mapping)
 {
-	struct radix_tree_iter iter;
-	void __rcu **slot;
-	pgoff_t start;
+	XA_STATE(xas, &mapping->i_pages, 0);
 	struct page *page;
 	int error, scan;
 
@@ -82,7 +80,9 @@ static int memfd_wait_for_pins(struct address_space *mapping)
 
 	error = 0;
 	for (scan = 0; scan <= LAST_SCAN; scan++) {
-		if (!radix_tree_tagged(&mapping->i_pages, MEMFD_TAG_PINNED))
+		unsigned int tagged = 0;
+
+		if (!xas_tagged(&xas, MEMFD_TAG_PINNED))
 			break;
 
 		if (!scan)
@@ -90,45 +90,34 @@ static int memfd_wait_for_pins(struct address_space *mapping)
 		else if (schedule_timeout_killable((HZ << scan) / 200))
 			scan = LAST_SCAN;
 
-		start = 0;
-		rcu_read_lock();
-		radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter,
-					   start, MEMFD_TAG_PINNED) {
-
-			page = radix_tree_deref_slot(slot);
-			if (radix_tree_exception(page)) {
-				if (radix_tree_deref_retry(page)) {
-					slot = radix_tree_iter_retry(&iter);
-					continue;
-				}
-
-				page = NULL;
-			}
-
-			if (page &&
-			    page_count(page) - page_mapcount(page) != 1) {
-				if (scan < LAST_SCAN)
-					goto continue_resched;
-
+		xas_set(&xas, 0);
+		xas_lock_irq(&xas);
+		xas_for_each_tagged(&xas, page, ULONG_MAX, MEMFD_TAG_PINNED) {
+			bool clear = true;
+			if (xa_is_value(page))
+				continue;
+			if (page_count(page) - page_mapcount(page) != 1) {
 				/*
 				 * On the last scan, we clean up all those tags
 				 * we inserted; but make a note that we still
 				 * found pages pinned.
 				 */
-				error = -EBUSY;
+				if (scan == LAST_SCAN)
+					error = -EBUSY;
+				else
+					clear = false;
 			}
+			if (clear)
+				xas_clear_tag(&xas, MEMFD_TAG_PINNED);
+			if (++tagged % XA_CHECK_SCHED)
+				continue;
 
-			xa_lock_irq(&mapping->i_pages);
-			radix_tree_tag_clear(&mapping->i_pages,
-					     iter.index, MEMFD_TAG_PINNED);
-			xa_unlock_irq(&mapping->i_pages);
-continue_resched:
-			if (need_resched()) {
-				slot = radix_tree_iter_resume(slot, &iter);
-				cond_resched_rcu();
-			}
+			xas_pause(&xas);
+			xas_unlock_irq(&xas);
+			cond_resched();
+			xas_lock_irq(&xas);
 		}
-		rcu_read_unlock();
+		xas_unlock_irq(&xas);
 	}
 
 	return error;
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 55/74] memfd: Convert memfd_tag_pins to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (53 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 54/74] memfd: Convert memfd_wait_for_pins " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 56/74] shmem: Comment fixups Matthew Wilcox
                   ` (19 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Switch to a batch-processing model like memfd_wait_for_pins() and
use the xa_state previously set up by memfd_wait_for_pins().

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
---
 mm/memfd.c | 44 ++++++++++++++++++--------------------------
 1 file changed, 18 insertions(+), 26 deletions(-)

diff --git a/mm/memfd.c b/mm/memfd.c
index e7d6be725b7a..636de8d5c7c3 100644
--- a/mm/memfd.c
+++ b/mm/memfd.c
@@ -28,37 +28,29 @@
 #define MEMFD_TAG_PINNED        PAGECACHE_TAG_TOWRITE
 #define LAST_SCAN               4       /* about 150ms max */
 
-static void memfd_tag_pins(struct address_space *mapping)
+static void memfd_tag_pins(struct xa_state *xas)
 {
-	struct radix_tree_iter iter;
-	void __rcu **slot;
-	pgoff_t start;
 	struct page *page;
+	unsigned int tagged = 0;
 
 	lru_add_drain();
-	start = 0;
-	rcu_read_lock();
-
-	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
-		page = radix_tree_deref_slot(slot);
-		if (!page || radix_tree_exception(page)) {
-			if (radix_tree_deref_retry(page)) {
-				slot = radix_tree_iter_retry(&iter);
-				continue;
-			}
-		} else if (page_count(page) - page_mapcount(page) > 1) {
-			xa_lock_irq(&mapping->i_pages);
-			radix_tree_tag_set(&mapping->i_pages, iter.index,
-					   MEMFD_TAG_PINNED);
-			xa_unlock_irq(&mapping->i_pages);
-		}
 
-		if (need_resched()) {
-			slot = radix_tree_iter_resume(slot, &iter);
-			cond_resched_rcu();
-		}
+	xas_lock_irq(xas);
+	xas_for_each(xas, page, ULONG_MAX) {
+		if (xa_is_value(page))
+			continue;
+		if (page_count(page) - page_mapcount(page) > 1)
+			xas_set_tag(xas, MEMFD_TAG_PINNED);
+
+		if (++tagged % XA_CHECK_SCHED)
+			continue;
+
+		xas_pause(xas);
+		xas_unlock_irq(xas);
+		cond_resched();
+		xas_lock_irq(xas);
 	}
-	rcu_read_unlock();
+	xas_unlock_irq(xas);
 }
 
 /*
@@ -76,7 +68,7 @@ static int memfd_wait_for_pins(struct address_space *mapping)
 	struct page *page;
 	int error, scan;
 
-	memfd_tag_pins(mapping);
+	memfd_tag_pins(&xas);
 
 	error = 0;
 	for (scan = 0; scan <= LAST_SCAN; scan++) {
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 56/74] shmem: Comment fixups
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (54 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 55/74] memfd: Convert memfd_tag_pins " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 57/74] btrfs: Convert page cache to XArray Matthew Wilcox
                   ` (18 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Remove the last mentions of radix tree from various comments.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 mm/shmem.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index bffb87854852..5f14acf95eff 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -766,7 +766,7 @@ void shmem_unlock_mapping(struct address_space *mapping)
 }
 
 /*
- * Remove range of pages and swap entries from radix tree, and free them.
+ * Remove range of pages and swap entries from page cache, and free them.
  * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
  */
 static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
@@ -1146,10 +1146,10 @@ static int shmem_unuse_inode(struct shmem_inode_info *info,
 		 * We needed to drop mutex to make that restrictive page
 		 * allocation, but the inode might have been freed while we
 		 * dropped it: although a racing shmem_evict_inode() cannot
-		 * complete without emptying the radix_tree, our page lock
+		 * complete without emptying the page cache, our page lock
 		 * on this swapcache page is not enough to prevent that -
 		 * free_swap_and_cache() of our swap entry will only
-		 * trylock_page(), removing swap from radix_tree whatever.
+		 * trylock_page(), removing swap from page cache whatever.
 		 *
 		 * We must not proceed to shmem_add_to_page_cache() if the
 		 * inode has been freed, but of course we cannot rely on
@@ -1215,7 +1215,7 @@ int shmem_unuse(swp_entry_t swap, struct page *page)
 			false);
 	if (error)
 		goto out;
-	/* No radix_tree_preload: swap entry keeps a place for page in tree */
+	/* No memory allocation: swap entry occupies the slot for the page */
 	error = -EAGAIN;
 
 	mutex_lock(&shmem_swaplist_mutex);
@@ -1889,7 +1889,7 @@ alloc_nohuge:		page = shmem_alloc_and_acct_page(gfp, inode,
 		spin_unlock_irq(&info->lock);
 		goto repeat;
 	}
-	if (error == -EEXIST)	/* from above or from radix_tree_insert */
+	if (error == -EEXIST)
 		goto repeat;
 	return error;
 }
@@ -2501,7 +2501,7 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 }
 
 /*
- * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
+ * llseek SEEK_DATA or SEEK_HOLE through the page cache.
  */
 static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
 				    pgoff_t index, pgoff_t end, int whence)
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 57/74] btrfs: Convert page cache to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (55 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 56/74] shmem: Comment fixups Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 58/74] fs: Convert buffer " Matthew Wilcox
                   ` (17 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Acked-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/compression.c | 4 +---
 fs/btrfs/extent_io.c   | 8 +++-----
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 8db29f791984..1d051d841cb7 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -444,9 +444,7 @@ static noinline int add_ra_bio_pages(struct inode *inode,
 		if (pg_index > end_index)
 			break;
 
-		rcu_read_lock();
-		page = radix_tree_lookup(&mapping->i_pages, pg_index);
-		rcu_read_unlock();
+		page = xa_load(&mapping->i_pages, pg_index);
 		if (page && !xa_is_value(page)) {
 			misses++;
 			if (misses > 4)
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index ac105d97dd81..e97aec67f52d 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -5169,11 +5169,9 @@ void clear_extent_buffer_dirty(struct extent_buffer *eb)
 
 		clear_page_dirty_for_io(page);
 		xa_lock_irq(&page->mapping->i_pages);
-		if (!PageDirty(page)) {
-			radix_tree_tag_clear(&page->mapping->i_pages,
-						page_index(page),
-						PAGECACHE_TAG_DIRTY);
-		}
+		if (!PageDirty(page))
+			__xa_clear_tag(&page->mapping->i_pages,
+					page_index(page), PAGECACHE_TAG_DIRTY);
 		xa_unlock_irq(&page->mapping->i_pages);
 		ClearPageError(page);
 		unlock_page(page);
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 58/74] fs: Convert buffer to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (56 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 57/74] btrfs: Convert page cache to XArray Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 59/74] fs: Convert writeback " Matthew Wilcox
                   ` (16 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Mostly comment fixes, but one use of __xa_set_tag.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 fs/buffer.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 8194e3049fc5..deae44fd64e9 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -562,7 +562,7 @@ void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
 EXPORT_SYMBOL(mark_buffer_dirty_inode);
 
 /*
- * Mark the page dirty, and set it dirty in the radix tree, and mark the inode
+ * Mark the page dirty, and set it dirty in the page cache, and mark the inode
  * dirty.
  *
  * If warn is true, then emit a warning if the page is not uptodate and has
@@ -579,8 +579,8 @@ void __set_page_dirty(struct page *page, struct address_space *mapping,
 	if (page->mapping) {	/* Race with truncate? */
 		WARN_ON_ONCE(warn && !PageUptodate(page));
 		account_page_dirtied(page, mapping);
-		radix_tree_tag_set(&mapping->i_pages,
-				page_index(page), PAGECACHE_TAG_DIRTY);
+		__xa_set_tag(&mapping->i_pages, page_index(page),
+				PAGECACHE_TAG_DIRTY);
 	}
 	xa_unlock_irqrestore(&mapping->i_pages, flags);
 }
@@ -1043,7 +1043,7 @@ __getblk_slow(struct block_device *bdev, sector_t block,
  * The relationship between dirty buffers and dirty pages:
  *
  * Whenever a page has any dirty buffers, the page's dirty bit is set, and
- * the page is tagged dirty in its radix tree.
+ * the page is tagged dirty in the page cache.
  *
  * At all times, the dirtiness of the buffers represents the dirtiness of
  * subsections of the page.  If the page has buffers, the page dirty bit is
@@ -1066,9 +1066,9 @@ __getblk_slow(struct block_device *bdev, sector_t block,
  * mark_buffer_dirty - mark a buffer_head as needing writeout
  * @bh: the buffer_head to mark dirty
  *
- * mark_buffer_dirty() will set the dirty bit against the buffer, then set its
- * backing page dirty, then tag the page as dirty in its address_space's radix
- * tree and then attach the address_space's inode to its superblock's dirty
+ * mark_buffer_dirty() will set the dirty bit against the buffer, then set
+ * its backing page dirty, then tag the page as dirty in the page cache
+ * and then attach the address_space's inode to its superblock's dirty
  * inode list.
  *
  * mark_buffer_dirty() is atomic.  It takes bh->b_page->mapping->private_lock,
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 59/74] fs: Convert writeback to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (57 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 58/74] fs: Convert buffer " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 60/74] nilfs2: Convert " Matthew Wilcox
                   ` (15 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

A couple of short loops.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 fs/fs-writeback.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 471d863958bc..137f241a3ee3 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -339,9 +339,9 @@ static void inode_switch_wbs_work_fn(struct work_struct *work)
 	struct address_space *mapping = inode->i_mapping;
 	struct bdi_writeback *old_wb = inode->i_wb;
 	struct bdi_writeback *new_wb = isw->new_wb;
-	struct radix_tree_iter iter;
+	XA_STATE(xas, &mapping->i_pages, 0);
+	struct page *page;
 	bool switched = false;
-	void **slot;
 
 	/*
 	 * By the time control reaches here, RCU grace period has passed
@@ -375,25 +375,18 @@ static void inode_switch_wbs_work_fn(struct work_struct *work)
 	 * to possibly dirty pages while PAGECACHE_TAG_WRITEBACK points to
 	 * pages actually under writeback.
 	 */
-	radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, 0,
-				   PAGECACHE_TAG_DIRTY) {
-		struct page *page = radix_tree_deref_slot_protected(slot,
-						&mapping->i_pages.xa_lock);
-		if (likely(page) && PageDirty(page)) {
+	xas_for_each_tagged(&xas, page, ULONG_MAX, PAGECACHE_TAG_DIRTY) {
+		if (PageDirty(page)) {
 			dec_wb_stat(old_wb, WB_RECLAIMABLE);
 			inc_wb_stat(new_wb, WB_RECLAIMABLE);
 		}
 	}
 
-	radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, 0,
-				   PAGECACHE_TAG_WRITEBACK) {
-		struct page *page = radix_tree_deref_slot_protected(slot,
-						&mapping->i_pages.xa_lock);
-		if (likely(page)) {
-			WARN_ON_ONCE(!PageWriteback(page));
-			dec_wb_stat(old_wb, WB_WRITEBACK);
-			inc_wb_stat(new_wb, WB_WRITEBACK);
-		}
+	xas_set(&xas, 0);
+	xas_for_each_tagged(&xas, page, ULONG_MAX, PAGECACHE_TAG_WRITEBACK) {
+		WARN_ON_ONCE(!PageWriteback(page));
+		dec_wb_stat(old_wb, WB_WRITEBACK);
+		inc_wb_stat(new_wb, WB_WRITEBACK);
 	}
 
 	wb_get(new_wb);
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 60/74] nilfs2: Convert to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (58 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 59/74] fs: Convert writeback " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 61/74] f2fs: " Matthew Wilcox
                   ` (14 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

This is close to a 1:1 replacement of radix tree APIs with their XArray
equivalents.  It would be possible to optimise nilfs_copy_back_pages(),
but that doesn't seem to be in the performance path.  Also, I think
it has a pre-existing bug, and I've added a note to that effect in the
source code.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 fs/nilfs2/btnode.c | 26 +++++++++-----------------
 fs/nilfs2/page.c   | 29 +++++++++++++----------------
 2 files changed, 22 insertions(+), 33 deletions(-)

diff --git a/fs/nilfs2/btnode.c b/fs/nilfs2/btnode.c
index dec98cab729d..e9fcffb3a15c 100644
--- a/fs/nilfs2/btnode.c
+++ b/fs/nilfs2/btnode.c
@@ -177,24 +177,18 @@ int nilfs_btnode_prepare_change_key(struct address_space *btnc,
 	ctxt->newbh = NULL;
 
 	if (inode->i_blkbits == PAGE_SHIFT) {
-		lock_page(obh->b_page);
-		/*
-		 * We cannot call radix_tree_preload for the kernels older
-		 * than 2.6.23, because it is not exported for modules.
-		 */
+		struct page *opage = obh->b_page;
+		lock_page(opage);
 retry:
-		err = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
-		if (err)
-			goto failed_unlock;
 		/* BUG_ON(oldkey != obh->b_page->index); */
-		if (unlikely(oldkey != obh->b_page->index))
-			NILFS_PAGE_BUG(obh->b_page,
+		if (unlikely(oldkey != opage->index))
+			NILFS_PAGE_BUG(opage,
 				       "invalid oldkey %lld (newkey=%lld)",
 				       (unsigned long long)oldkey,
 				       (unsigned long long)newkey);
 
 		xa_lock_irq(&btnc->i_pages);
-		err = radix_tree_insert(&btnc->i_pages, newkey, obh->b_page);
+		err = __xa_insert(&btnc->i_pages, newkey, opage, GFP_NOFS);
 		xa_unlock_irq(&btnc->i_pages);
 		/*
 		 * Note: page->index will not change to newkey until
@@ -202,7 +196,6 @@ int nilfs_btnode_prepare_change_key(struct address_space *btnc,
 		 * To protect the page in intermediate state, the page lock
 		 * is held.
 		 */
-		radix_tree_preload_end();
 		if (!err)
 			return 0;
 		else if (err != -EEXIST)
@@ -212,7 +205,7 @@ int nilfs_btnode_prepare_change_key(struct address_space *btnc,
 		if (!err)
 			goto retry;
 		/* fallback to copy mode */
-		unlock_page(obh->b_page);
+		unlock_page(opage);
 	}
 
 	nbh = nilfs_btnode_create_block(btnc, newkey);
@@ -252,9 +245,8 @@ void nilfs_btnode_commit_change_key(struct address_space *btnc,
 		mark_buffer_dirty(obh);
 
 		xa_lock_irq(&btnc->i_pages);
-		radix_tree_delete(&btnc->i_pages, oldkey);
-		radix_tree_tag_set(&btnc->i_pages, newkey,
-				   PAGECACHE_TAG_DIRTY);
+		__xa_erase(&btnc->i_pages, oldkey);
+		__xa_set_tag(&btnc->i_pages, newkey, PAGECACHE_TAG_DIRTY);
 		xa_unlock_irq(&btnc->i_pages);
 
 		opage->index = obh->b_blocknr = newkey;
@@ -284,7 +276,7 @@ void nilfs_btnode_abort_change_key(struct address_space *btnc,
 
 	if (nbh == NULL) {	/* blocksize == pagesize */
 		xa_lock_irq(&btnc->i_pages);
-		radix_tree_delete(&btnc->i_pages, newkey);
+		__xa_erase(&btnc->i_pages, newkey);
 		xa_unlock_irq(&btnc->i_pages);
 		unlock_page(ctxt->bh->b_page);
 	} else
diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c
index 4cb850a6f1c2..8384473b98b8 100644
--- a/fs/nilfs2/page.c
+++ b/fs/nilfs2/page.c
@@ -298,7 +298,7 @@ int nilfs_copy_dirty_pages(struct address_space *dmap,
  * @dmap: destination page cache
  * @smap: source page cache
  *
- * No pages must no be added to the cache during this process.
+ * No pages must be added to the cache during this process.
  * This must be ensured by the caller.
  */
 void nilfs_copy_back_pages(struct address_space *dmap,
@@ -307,7 +307,6 @@ void nilfs_copy_back_pages(struct address_space *dmap,
 	struct pagevec pvec;
 	unsigned int i, n;
 	pgoff_t index = 0;
-	int err;
 
 	pagevec_init(&pvec);
 repeat:
@@ -322,35 +321,34 @@ void nilfs_copy_back_pages(struct address_space *dmap,
 		lock_page(page);
 		dpage = find_lock_page(dmap, offset);
 		if (dpage) {
-			/* override existing page on the destination cache */
+			/* overwrite existing page in the destination cache */
 			WARN_ON(PageDirty(dpage));
 			nilfs_copy_page(dpage, page, 0);
 			unlock_page(dpage);
 			put_page(dpage);
+			/* Do we not need to remove page from smap here? */
 		} else {
-			struct page *page2;
+			struct page *p;
 
 			/* move the page to the destination cache */
 			xa_lock_irq(&smap->i_pages);
-			page2 = radix_tree_delete(&smap->i_pages, offset);
-			WARN_ON(page2 != page);
-
+			p = __xa_erase(&smap->i_pages, offset);
+			WARN_ON(page != p);
 			smap->nrpages--;
 			xa_unlock_irq(&smap->i_pages);
 
 			xa_lock_irq(&dmap->i_pages);
-			err = radix_tree_insert(&dmap->i_pages, offset, page);
-			if (unlikely(err < 0)) {
-				WARN_ON(err == -EEXIST);
+			p = __xa_store(&dmap->i_pages, offset, page, GFP_NOFS);
+			if (unlikely(p)) {
+				/* Probably -ENOMEM */
 				page->mapping = NULL;
-				put_page(page); /* for cache */
+				put_page(page);
 			} else {
 				page->mapping = dmap;
 				dmap->nrpages++;
 				if (PageDirty(page))
-					radix_tree_tag_set(&dmap->i_pages,
-							   offset,
-							   PAGECACHE_TAG_DIRTY);
+					__xa_set_tag(&dmap->i_pages, offset,
+							PAGECACHE_TAG_DIRTY);
 			}
 			xa_unlock_irq(&dmap->i_pages);
 		}
@@ -476,8 +474,7 @@ int __nilfs_clear_page_dirty(struct page *page)
 	if (mapping) {
 		xa_lock_irq(&mapping->i_pages);
 		if (test_bit(PG_dirty, &page->flags)) {
-			radix_tree_tag_clear(&mapping->i_pages,
-					     page_index(page),
+			__xa_clear_tag(&mapping->i_pages, page_index(page),
 					     PAGECACHE_TAG_DIRTY);
 			xa_unlock_irq(&mapping->i_pages);
 			return clear_page_dirty_for_io(page);
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 61/74] f2fs: Convert to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (59 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 60/74] nilfs2: Convert " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 62/74] dax: Rename some functions Matthew Wilcox
                   ` (13 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

This is a straightforward conversion.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 fs/f2fs/data.c   | 4 ++--
 fs/f2fs/dir.c    | 2 +-
 fs/f2fs/f2fs.h   | 2 +-
 fs/f2fs/inline.c | 2 +-
 fs/f2fs/node.c   | 6 ++----
 5 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index e5c0b1e74ce6..b274300995cd 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2600,13 +2600,13 @@ const struct address_space_operations f2fs_dblock_aops = {
 #endif
 };
 
-void f2fs_clear_radix_tree_dirty_tag(struct page *page)
+void f2fs_clear_page_cache_dirty_tag(struct page *page)
 {
 	struct address_space *mapping = page_mapping(page);
 	unsigned long flags;
 
 	xa_lock_irqsave(&mapping->i_pages, flags);
-	radix_tree_tag_clear(&mapping->i_pages, page_index(page),
+	__xa_clear_tag(&mapping->i_pages, page_index(page),
 						PAGECACHE_TAG_DIRTY);
 	xa_unlock_irqrestore(&mapping->i_pages, flags);
 }
diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index 7f955c4e86a4..9c2a23242f64 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -730,7 +730,7 @@ void f2fs_delete_entry(struct f2fs_dir_entry *dentry, struct page *page,
 
 	if (bit_pos == NR_DENTRY_IN_BLOCK &&
 		!f2fs_truncate_hole(dir, page->index, page->index + 1)) {
-		f2fs_clear_radix_tree_dirty_tag(page);
+		f2fs_clear_page_cache_dirty_tag(page);
 		clear_page_dirty_for_io(page);
 		ClearPagePrivate(page);
 		ClearPageUptodate(page);
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 4d8b1de83143..1f71ab2ddad9 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2973,7 +2973,7 @@ int f2fs_migrate_page(struct address_space *mapping, struct page *newpage,
 			struct page *page, enum migrate_mode mode);
 #endif
 bool f2fs_overwrite_io(struct inode *inode, loff_t pos, size_t len);
-void f2fs_clear_radix_tree_dirty_tag(struct page *page);
+void f2fs_clear_page_cache_dirty_tag(struct page *page);
 
 /*
  * gc.c
diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
index 043830be5662..48f40d344a2a 100644
--- a/fs/f2fs/inline.c
+++ b/fs/f2fs/inline.c
@@ -226,7 +226,7 @@ int f2fs_write_inline_data(struct inode *inode, struct page *page)
 	kunmap_atomic(src_addr);
 	set_page_dirty(dn.inode_page);
 
-	f2fs_clear_radix_tree_dirty_tag(page);
+	f2fs_clear_page_cache_dirty_tag(page);
 
 	set_inode_flag(inode, FI_APPEND_WRITE);
 	set_inode_flag(inode, FI_DATA_EXIST);
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index 10643b11bd59..9aa076be8a0e 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -103,7 +103,7 @@ bool f2fs_available_free_memory(struct f2fs_sb_info *sbi, int type)
 static void clear_node_page_dirty(struct page *page)
 {
 	if (PageDirty(page)) {
-		f2fs_clear_radix_tree_dirty_tag(page);
+		f2fs_clear_page_cache_dirty_tag(page);
 		clear_page_dirty_for_io(page);
 		dec_page_count(F2FS_P_SB(page), F2FS_DIRTY_NODES);
 	}
@@ -1168,9 +1168,7 @@ void f2fs_ra_node_page(struct f2fs_sb_info *sbi, nid_t nid)
 	if (f2fs_check_nid_range(sbi, nid))
 		return;
 
-	rcu_read_lock();
-	apage = radix_tree_lookup(&NODE_MAPPING(sbi)->i_pages, nid);
-	rcu_read_unlock();
+	apage = xa_load(&NODE_MAPPING(sbi)->i_pages, nid);
 	if (apage)
 		return;
 
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 62/74] dax: Rename some functions
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (60 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 61/74] f2fs: " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 63/74] dax: Hash on XArray instead of mapping Matthew Wilcox
                   ` (12 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Remove mentions of 'radix' and 'radix tree'.  Simplify some names by
dropping the word 'mapping'.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 fs/dax.c | 86 +++++++++++++++++++++++++++-----------------------------
 1 file changed, 42 insertions(+), 44 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 704059ecfa88..157762fe2ba1 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -74,18 +74,18 @@ fs_initcall(init_dax_wait_table);
 #define DAX_ZERO_PAGE	(1UL << 2)
 #define DAX_EMPTY	(1UL << 3)
 
-static unsigned long dax_radix_pfn(void *entry)
+static unsigned long dax_to_pfn(void *entry)
 {
 	return xa_to_value(entry) >> DAX_SHIFT;
 }
 
-static void *dax_radix_locked_entry(unsigned long pfn, unsigned long flags)
+static void *dax_make_locked(unsigned long pfn, unsigned long flags)
 {
 	return xa_mk_value(flags | ((unsigned long)pfn << DAX_SHIFT) |
 			DAX_LOCKED);
 }
 
-static unsigned int dax_radix_order(void *entry)
+static unsigned int dax_entry_order(void *entry)
 {
 	if (xa_to_value(entry) & DAX_PMD)
 		return PMD_SHIFT - PAGE_SHIFT;
@@ -113,7 +113,7 @@ static int dax_is_empty_entry(void *entry)
 }
 
 /*
- * DAX radix tree locking
+ * DAX page cache entry locking
  */
 struct exceptional_entry_key {
 	struct address_space *mapping;
@@ -217,7 +217,7 @@ static inline void *unlock_slot(struct address_space *mapping, void **slot)
 }
 
 /*
- * Lookup entry in radix tree, wait for it to become unlocked if it is
+ * Lookup entry in page cache, wait for it to become unlocked if it is
  * a DAX entry and return it. The caller must call
  * put_unlocked_mapping_entry() when he decided not to lock the entry or
  * put_locked_mapping_entry() when he locked the entry and now wants to
@@ -280,7 +280,7 @@ static void put_locked_mapping_entry(struct address_space *mapping,
 }
 
 /*
- * Called when we are done with radix tree entry we looked up via
+ * Called when we are done with page cache entry we looked up via
  * get_unlocked_mapping_entry() and which we didn't lock in the end.
  */
 static void put_unlocked_mapping_entry(struct address_space *mapping,
@@ -289,7 +289,7 @@ static void put_unlocked_mapping_entry(struct address_space *mapping,
 	if (!entry)
 		return;
 
-	/* We have to wake up next waiter for the radix tree entry lock */
+	/* We have to wake up next waiter for the page cache entry lock */
 	dax_wake_mapping_entry_waiter(mapping, index, entry, false);
 }
 
@@ -305,9 +305,9 @@ static unsigned long dax_entry_size(void *entry)
 		return PAGE_SIZE;
 }
 
-static unsigned long dax_radix_end_pfn(void *entry)
+static unsigned long dax_end_pfn(void *entry)
 {
-	return dax_radix_pfn(entry) + dax_entry_size(entry) / PAGE_SIZE;
+	return dax_to_pfn(entry) + dax_entry_size(entry) / PAGE_SIZE;
 }
 
 /*
@@ -315,8 +315,8 @@ static unsigned long dax_radix_end_pfn(void *entry)
  * 'empty' and 'zero' entries.
  */
 #define for_each_mapped_pfn(entry, pfn) \
-	for (pfn = dax_radix_pfn(entry); \
-			pfn < dax_radix_end_pfn(entry); pfn++)
+	for (pfn = dax_to_pfn(entry); \
+			pfn < dax_end_pfn(entry); pfn++)
 
 /*
  * TODO: for reflink+dax we need a way to associate a single page with
@@ -449,9 +449,9 @@ void dax_unlock_page(struct page *page)
 }
 
 /*
- * Find radix tree entry at given index. If it is a DAX entry, return it
- * with the radix tree entry locked. If the radix tree doesn't contain the
- * given index, create an empty entry for the index and return with it locked.
+ * Find page cache entry at given index. If it is a DAX entry, return it
+ * with the entry locked. If the page cache doesn't contain an entry at
+ * that index, add a locked empty entry.
  *
  * When requesting an entry with size DAX_PMD, grab_mapping_entry() will
  * either return that locked entry or will return an error.  This error will
@@ -560,10 +560,10 @@ static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index,
 					true);
 		}
 
-		entry = dax_radix_locked_entry(0, size_flag | DAX_EMPTY);
+		entry = dax_make_locked(0, size_flag | DAX_EMPTY);
 
 		err = __radix_tree_insert(&mapping->i_pages, index,
-				dax_radix_order(entry), entry);
+				dax_entry_order(entry), entry);
 		radix_tree_preload_end();
 		if (err) {
 			xa_unlock_irq(&mapping->i_pages);
@@ -672,7 +672,7 @@ struct page *dax_layout_busy_page(struct address_space *mapping)
 }
 EXPORT_SYMBOL_GPL(dax_layout_busy_page);
 
-static int __dax_invalidate_mapping_entry(struct address_space *mapping,
+static int __dax_invalidate_entry(struct address_space *mapping,
 					  pgoff_t index, bool trunc)
 {
 	int ret = 0;
@@ -702,12 +702,12 @@ static int __dax_invalidate_mapping_entry(struct address_space *mapping,
  */
 int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index)
 {
-	int ret = __dax_invalidate_mapping_entry(mapping, index, true);
+	int ret = __dax_invalidate_entry(mapping, index, true);
 
 	/*
 	 * This gets called from truncate / punch_hole path. As such, the caller
 	 * must hold locks protecting against concurrent modifications of the
-	 * radix tree (usually fs-private i_mmap_sem for writing). Since the
+	 * page cache (usually fs-private i_mmap_sem for writing). Since the
 	 * caller has seen a DAX entry for this index, we better find it
 	 * at that index as well...
 	 */
@@ -721,7 +721,7 @@ int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index)
 int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
 				      pgoff_t index)
 {
-	return __dax_invalidate_mapping_entry(mapping, index, false);
+	return __dax_invalidate_entry(mapping, index, false);
 }
 
 static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev,
@@ -758,10 +758,9 @@ static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev,
  * already in the tree, we will skip the insertion and just dirty the PMD as
  * appropriate.
  */
-static void *dax_insert_mapping_entry(struct address_space *mapping,
-				      struct vm_fault *vmf,
-				      void *entry, pfn_t pfn_t,
-				      unsigned long flags, bool dirty)
+static void *dax_insert_entry(struct address_space *mapping,
+		struct vm_fault *vmf,
+		void *entry, pfn_t pfn_t, unsigned long flags, bool dirty)
 {
 	struct radix_tree_root *pages = &mapping->i_pages;
 	unsigned long pfn = pfn_t_to_pfn(pfn_t);
@@ -781,7 +780,7 @@ static void *dax_insert_mapping_entry(struct address_space *mapping,
 	}
 
 	xa_lock_irq(pages);
-	new_entry = dax_radix_locked_entry(pfn, flags);
+	new_entry = dax_make_locked(pfn, flags);
 	if (dax_entry_size(entry) != dax_entry_size(new_entry)) {
 		dax_disassociate_entry(entry, mapping, false);
 		dax_associate_entry(new_entry, mapping, vmf->vma, vmf->address);
@@ -789,9 +788,9 @@ static void *dax_insert_mapping_entry(struct address_space *mapping,
 
 	if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {
 		/*
-		 * Only swap our new entry into the radix tree if the current
+		 * Only swap our new entry into the page cache if the current
 		 * entry is a zero page or an empty entry.  If a normal PTE or
-		 * PMD entry is already in the tree, we leave it alone.  This
+		 * PMD entry is already in the cache, we leave it alone.  This
 		 * means that if we are trying to insert a PTE and the
 		 * existing entry is a PMD, we will just leave the PMD in the
 		 * tree and dirty it if necessary.
@@ -814,8 +813,8 @@ static void *dax_insert_mapping_entry(struct address_space *mapping,
 	return entry;
 }
 
-static inline unsigned long
-pgoff_address(pgoff_t pgoff, struct vm_area_struct *vma)
+static inline
+unsigned long pgoff_address(pgoff_t pgoff, struct vm_area_struct *vma)
 {
 	unsigned long address;
 
@@ -825,8 +824,8 @@ pgoff_address(pgoff_t pgoff, struct vm_area_struct *vma)
 }
 
 /* Walk all mappings of a given index of a file and writeprotect them */
-static void dax_mapping_entry_mkclean(struct address_space *mapping,
-				      pgoff_t index, unsigned long pfn)
+static void dax_entry_mkclean(struct address_space *mapping, pgoff_t index,
+		unsigned long pfn)
 {
 	struct vm_area_struct *vma;
 	pte_t pte, *ptep = NULL;
@@ -922,7 +921,7 @@ static int dax_writeback_one(struct dax_device *dax_dev,
 	 * compare pfns as we must not bail out due to difference in lockbit
 	 * or entry type.
 	 */
-	if (dax_radix_pfn(entry2) != dax_radix_pfn(entry))
+	if (dax_to_pfn(entry2) != dax_to_pfn(entry))
 		goto put_unlocked;
 	if (WARN_ON_ONCE(dax_is_empty_entry(entry) ||
 				dax_is_zero_entry(entry))) {
@@ -952,10 +951,10 @@ static int dax_writeback_one(struct dax_device *dax_dev,
 	 * This allows us to flush for PMD_SIZE and not have to worry about
 	 * partial PMD writebacks.
 	 */
-	pfn = dax_radix_pfn(entry);
-	size = PAGE_SIZE << dax_radix_order(entry);
+	pfn = dax_to_pfn(entry);
+	size = PAGE_SIZE << dax_entry_order(entry);
 
-	dax_mapping_entry_mkclean(mapping, index, pfn);
+	dax_entry_mkclean(mapping, index, pfn);
 	dax_flush(dax_dev, page_address(pfn_to_page(pfn)), size);
 	/*
 	 * After we have flushed the cache, we can clear the dirty tag. There
@@ -1093,7 +1092,7 @@ static vm_fault_t dax_load_hole(struct address_space *mapping, void *entry,
 	pfn_t pfn = pfn_to_pfn_t(my_zero_pfn(vaddr));
 	vm_fault_t ret;
 
-	dax_insert_mapping_entry(mapping, vmf, entry, pfn,
+	dax_insert_entry(mapping, vmf, entry, pfn,
 			DAX_ZERO_PAGE, false);
 
 	ret = vmf_insert_mixed(vmf->vma, vaddr, pfn);
@@ -1407,7 +1406,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
 		if (error < 0)
 			goto error_finish_iomap;
 
-		entry = dax_insert_mapping_entry(mapping, vmf, entry, pfn,
+		entry = dax_insert_entry(mapping, vmf, entry, pfn,
 						 0, write && !sync);
 
 		/*
@@ -1487,7 +1486,7 @@ static vm_fault_t dax_pmd_load_hole(struct vm_fault *vmf, struct iomap *iomap,
 		goto fallback;
 
 	pfn = page_to_pfn_t(zero_page);
-	ret = dax_insert_mapping_entry(mapping, vmf, entry, pfn,
+	ret = dax_insert_entry(mapping, vmf, entry, pfn,
 			DAX_PMD | DAX_ZERO_PAGE, false);
 
 	ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
@@ -1540,7 +1539,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	 * Make sure that the faulting address's PMD offset (color) matches
 	 * the PMD offset from the start of the file.  This is necessary so
 	 * that a PMD range in the page table overlaps exactly with a PMD
-	 * range in the radix tree.
+	 * range in the page cache.
 	 */
 	if ((vmf->pgoff & PG_PMD_COLOUR) !=
 	    ((vmf->address >> PAGE_SHIFT) & PG_PMD_COLOUR))
@@ -1608,7 +1607,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 		if (error < 0)
 			goto finish_iomap;
 
-		entry = dax_insert_mapping_entry(mapping, vmf, entry, pfn,
+		entry = dax_insert_entry(mapping, vmf, entry, pfn,
 						DAX_PMD, write && !sync);
 
 		/*
@@ -1701,15 +1700,14 @@ vm_fault_t dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
 }
 EXPORT_SYMBOL_GPL(dax_iomap_fault);
 
-/**
+/*
  * dax_insert_pfn_mkwrite - insert PTE or PMD entry into page tables
  * @vmf: The description of the fault
  * @pe_size: Size of entry to be inserted
  * @pfn: PFN to insert
  *
- * This function inserts writeable PTE or PMD entry into page tables for mmaped
- * DAX file.  It takes care of marking corresponding radix tree entry as dirty
- * as well.
+ * This function inserts a writeable PTE or PMD entry into the page tables
+ * for an mmaped DAX file.  It also marks the page cache entry as dirty.
  */
 static vm_fault_t dax_insert_pfn_mkwrite(struct vm_fault *vmf,
 				  enum page_entry_size pe_size,
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 63/74] dax: Hash on XArray instead of mapping
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (61 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 62/74] dax: Rename some functions Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 64/74] dax: Convert dax_insert_pfn_mkwrite to XArray Matthew Wilcox
                   ` (11 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Since the XArray is embedded in the struct address_space, its address
contains exactly as much entropy as the address of the mapping.  This
patch is purely preparatory for later patches which will simplify the
wait/wake interfaces.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 fs/dax.c | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 157762fe2ba1..b7f54e386da8 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -116,7 +116,7 @@ static int dax_is_empty_entry(void *entry)
  * DAX page cache entry locking
  */
 struct exceptional_entry_key {
-	struct address_space *mapping;
+	struct xarray *xa;
 	pgoff_t entry_start;
 };
 
@@ -125,7 +125,7 @@ struct wait_exceptional_entry_queue {
 	struct exceptional_entry_key key;
 };
 
-static wait_queue_head_t *dax_entry_waitqueue(struct address_space *mapping,
+static wait_queue_head_t *dax_entry_waitqueue(struct xarray *xa,
 		pgoff_t index, void *entry, struct exceptional_entry_key *key)
 {
 	unsigned long hash;
@@ -138,21 +138,21 @@ static wait_queue_head_t *dax_entry_waitqueue(struct address_space *mapping,
 	if (dax_is_pmd_entry(entry))
 		index &= ~PG_PMD_COLOUR;
 
-	key->mapping = mapping;
+	key->xa = xa;
 	key->entry_start = index;
 
-	hash = hash_long((unsigned long)mapping ^ index, DAX_WAIT_TABLE_BITS);
+	hash = hash_long((unsigned long)xa ^ index, DAX_WAIT_TABLE_BITS);
 	return wait_table + hash;
 }
 
-static int wake_exceptional_entry_func(wait_queue_entry_t *wait, unsigned int mode,
-				       int sync, void *keyp)
+static int wake_exceptional_entry_func(wait_queue_entry_t *wait,
+		unsigned int mode, int sync, void *keyp)
 {
 	struct exceptional_entry_key *key = keyp;
 	struct wait_exceptional_entry_queue *ewait =
 		container_of(wait, struct wait_exceptional_entry_queue, wait);
 
-	if (key->mapping != ewait->key.mapping ||
+	if (key->xa != ewait->key.xa ||
 	    key->entry_start != ewait->key.entry_start)
 		return 0;
 	return autoremove_wake_function(wait, mode, sync, NULL);
@@ -163,13 +163,13 @@ static int wake_exceptional_entry_func(wait_queue_entry_t *wait, unsigned int mo
  * The important information it's conveying is whether the entry at
  * this index used to be a PMD entry.
  */
-static void dax_wake_mapping_entry_waiter(struct address_space *mapping,
+static void dax_wake_mapping_entry_waiter(struct xarray *xa,
 		pgoff_t index, void *entry, bool wake_all)
 {
 	struct exceptional_entry_key key;
 	wait_queue_head_t *wq;
 
-	wq = dax_entry_waitqueue(mapping, index, entry, &key);
+	wq = dax_entry_waitqueue(xa, index, entry, &key);
 
 	/*
 	 * Checking for locked entry and prepare_to_wait_exclusive() happens
@@ -246,7 +246,8 @@ static void *get_unlocked_mapping_entry(struct address_space *mapping,
 			return entry;
 		}
 
-		wq = dax_entry_waitqueue(mapping, index, entry, &ewait.key);
+		wq = dax_entry_waitqueue(&mapping->i_pages, index, entry,
+				&ewait.key);
 		prepare_to_wait_exclusive(wq, &ewait.wait,
 					  TASK_UNINTERRUPTIBLE);
 		xa_unlock_irq(&mapping->i_pages);
@@ -270,7 +271,7 @@ static void dax_unlock_mapping_entry(struct address_space *mapping,
 	}
 	unlock_slot(mapping, slot);
 	xa_unlock_irq(&mapping->i_pages);
-	dax_wake_mapping_entry_waiter(mapping, index, entry, false);
+	dax_wake_mapping_entry_waiter(&mapping->i_pages, index, entry, false);
 }
 
 static void put_locked_mapping_entry(struct address_space *mapping,
@@ -290,7 +291,7 @@ static void put_unlocked_mapping_entry(struct address_space *mapping,
 		return;
 
 	/* We have to wake up next waiter for the page cache entry lock */
-	dax_wake_mapping_entry_waiter(mapping, index, entry, false);
+	dax_wake_mapping_entry_waiter(&mapping->i_pages, index, entry, false);
 }
 
 static unsigned long dax_entry_size(void *entry)
@@ -423,7 +424,8 @@ struct page *dax_lock_page(unsigned long pfn)
 			break;
 		}
 
-		wq = dax_entry_waitqueue(mapping, index, entry, &ewait.key);
+		wq = dax_entry_waitqueue(&mapping->i_pages, index, entry,
+				&ewait.key);
 		prepare_to_wait_exclusive(wq, &ewait.wait,
 				TASK_UNINTERRUPTIBLE);
 		xa_unlock_irq(&mapping->i_pages);
@@ -556,8 +558,8 @@ static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index,
 			dax_disassociate_entry(entry, mapping, false);
 			radix_tree_delete(&mapping->i_pages, index);
 			mapping->nrexceptional--;
-			dax_wake_mapping_entry_waiter(mapping, index, entry,
-					true);
+			dax_wake_mapping_entry_waiter(&mapping->i_pages,
+					index, entry, true);
 		}
 
 		entry = dax_make_locked(0, size_flag | DAX_EMPTY);
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 64/74] dax: Convert dax_insert_pfn_mkwrite to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (62 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 63/74] dax: Hash on XArray instead of mapping Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 65/74] dax: Convert dax_layout_busy_page " Matthew Wilcox
                   ` (10 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Add some XArray-based helper functions to replace the radix tree based
metaphors currently in use.  The biggest change is that converted code
doesn't see its own lock bit; get_unlocked_entry() always returns an
entry with the lock bit clear, and locking the entry now returns void.
So we don't have to mess around loading the current entry and clearing
the lock bit; we can just store the entry that we were using.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 fs/dax.c | 145 +++++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 113 insertions(+), 32 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index b7f54e386da8..71181f4bb1d3 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -38,6 +38,17 @@
 #define CREATE_TRACE_POINTS
 #include <trace/events/fs_dax.h>
 
+static inline unsigned int pe_order(enum page_entry_size pe_size)
+{
+	if (pe_size == PE_SIZE_PTE)
+		return PAGE_SHIFT - PAGE_SHIFT;
+	if (pe_size == PE_SIZE_PMD)
+		return PMD_SHIFT - PAGE_SHIFT;
+	if (pe_size == PE_SIZE_PUD)
+		return PUD_SHIFT - PAGE_SHIFT;
+	return ~0;
+}
+
 /* We choose 4096 entries - same as per-zone page wait tables */
 #define DAX_WAIT_TABLE_BITS 12
 #define DAX_WAIT_TABLE_ENTRIES (1 << DAX_WAIT_TABLE_BITS)
@@ -46,6 +57,9 @@
 #define PG_PMD_COLOUR	((PMD_SIZE >> PAGE_SHIFT) - 1)
 #define PG_PMD_NR	(PMD_SIZE >> PAGE_SHIFT)
 
+/* The order of a PMD entry */
+#define PMD_ORDER	(PMD_SHIFT - PAGE_SHIFT)
+
 static wait_queue_head_t wait_table[DAX_WAIT_TABLE_ENTRIES];
 
 static int __init init_dax_wait_table(void)
@@ -85,10 +99,15 @@ static void *dax_make_locked(unsigned long pfn, unsigned long flags)
 			DAX_LOCKED);
 }
 
+static bool dax_is_locked(void *entry)
+{
+	return xa_to_value(entry) & DAX_LOCKED;
+}
+
 static unsigned int dax_entry_order(void *entry)
 {
 	if (xa_to_value(entry) & DAX_PMD)
-		return PMD_SHIFT - PAGE_SHIFT;
+		return PMD_ORDER;
 	return 0;
 }
 
@@ -181,6 +200,77 @@ static void dax_wake_mapping_entry_waiter(struct xarray *xa,
 		__wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
 }
 
+static void dax_wake_entry(struct xa_state *xas, void *entry, bool wake_all)
+{
+	return dax_wake_mapping_entry_waiter(xas->xa, xas->xa_index, entry,
+								wake_all);
+}
+
+/*
+ * Look up entry in page cache, wait for it to become unlocked if it
+ * is a DAX entry and return it.  The caller must subsequently call
+ * put_unlocked_entry() if it did not lock the entry or put_locked_entry()
+ * if it did.
+ *
+ * Must be called with the i_pages lock held.
+ */
+static void *get_unlocked_entry(struct xa_state *xas)
+{
+	void *entry;
+	struct wait_exceptional_entry_queue ewait;
+	wait_queue_head_t *wq;
+
+	init_wait(&ewait.wait);
+	ewait.wait.func = wake_exceptional_entry_func;
+
+	for (;;) {
+		entry = xas_load(xas);
+		if (!entry || WARN_ON_ONCE(!xa_is_value(entry)) ||
+				!dax_is_locked(entry))
+			return entry;
+
+		wq = dax_entry_waitqueue(xas->xa, xas->xa_index, entry,
+				&ewait.key);
+		prepare_to_wait_exclusive(wq, &ewait.wait,
+					  TASK_UNINTERRUPTIBLE);
+		xas_unlock_irq(xas);
+		xas_reset(xas);
+		schedule();
+		finish_wait(wq, &ewait.wait);
+		xas_lock_irq(xas);
+	}
+}
+
+static void put_unlocked_entry(struct xa_state *xas, void *entry)
+{
+	/* If we were the only waiter woken, wake the next one */
+	if (entry)
+		dax_wake_entry(xas, entry, false);
+}
+
+/*
+ * We used the xa_state to get the entry, but then we locked the entry and
+ * dropped the xa_lock, so we know the xa_state is stale and must be reset
+ * before use.
+ */
+static void put_locked_entry(struct xa_state *xas, void *entry)
+{
+	void *old;
+
+	xas_reset(xas);
+	xas_lock_irq(xas);
+	old = xas_store(xas, entry);
+	xas_unlock_irq(xas);
+	BUG_ON(!dax_is_locked(old));
+	dax_wake_entry(xas, entry, false);
+}
+
+static void dax_lock_entry(struct xa_state *xas, void *entry)
+{
+	unsigned long v = xa_to_value(entry);
+	xas_store(xas, xa_mk_value(v | DAX_LOCKED));
+}
+
 /*
  * Check whether the given slot is locked.  Must be called with the i_pages
  * lock held.
@@ -1705,50 +1795,46 @@ EXPORT_SYMBOL_GPL(dax_iomap_fault);
 /*
  * dax_insert_pfn_mkwrite - insert PTE or PMD entry into page tables
  * @vmf: The description of the fault
- * @pe_size: Size of entry to be inserted
  * @pfn: PFN to insert
+ * @order: Order of entry to insert.
  *
  * This function inserts a writeable PTE or PMD entry into the page tables
  * for an mmaped DAX file.  It also marks the page cache entry as dirty.
  */
-static vm_fault_t dax_insert_pfn_mkwrite(struct vm_fault *vmf,
-				  enum page_entry_size pe_size,
-				  pfn_t pfn)
+static vm_fault_t
+dax_insert_pfn_mkwrite(struct vm_fault *vmf, pfn_t pfn, unsigned int order)
 {
 	struct address_space *mapping = vmf->vma->vm_file->f_mapping;
-	void *entry, **slot;
-	pgoff_t index = vmf->pgoff;
+	XA_STATE_ORDER(xas, &mapping->i_pages, vmf->pgoff, order);
+	void *entry;
 	vm_fault_t ret;
 
-	xa_lock_irq(&mapping->i_pages);
-	entry = get_unlocked_mapping_entry(mapping, index, &slot);
+	xas_lock_irq(&xas);
+	entry = get_unlocked_entry(&xas);
 	/* Did we race with someone splitting entry or so? */
 	if (!entry ||
-	    (pe_size == PE_SIZE_PTE && !dax_is_pte_entry(entry)) ||
-	    (pe_size == PE_SIZE_PMD && !dax_is_pmd_entry(entry))) {
-		put_unlocked_mapping_entry(mapping, index, entry);
-		xa_unlock_irq(&mapping->i_pages);
+	    (order == 0 && !dax_is_pte_entry(entry)) ||
+	    (order == PMD_ORDER && (xa_is_internal(entry) ||
+				    !dax_is_pmd_entry(entry)))) {
+		put_unlocked_entry(&xas, entry);
+		xas_unlock_irq(&xas);
 		trace_dax_insert_pfn_mkwrite_no_entry(mapping->host, vmf,
 						      VM_FAULT_NOPAGE);
 		return VM_FAULT_NOPAGE;
 	}
-	radix_tree_tag_set(&mapping->i_pages, index, PAGECACHE_TAG_DIRTY);
-	entry = lock_slot(mapping, slot);
-	xa_unlock_irq(&mapping->i_pages);
-	switch (pe_size) {
-	case PE_SIZE_PTE:
+	xas_set_tag(&xas, PAGECACHE_TAG_DIRTY);
+	dax_lock_entry(&xas, entry);
+	xas_unlock_irq(&xas);
+	if (order == 0)
 		ret = vmf_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn);
-		break;
 #ifdef CONFIG_FS_DAX_PMD
-	case PE_SIZE_PMD:
+	else if (order == PMD_ORDER)
 		ret = vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd,
 			pfn, true);
-		break;
 #endif
-	default:
+	else
 		ret = VM_FAULT_FALLBACK;
-	}
-	put_locked_mapping_entry(mapping, index);
+	put_locked_entry(&xas, entry);
 	trace_dax_insert_pfn_mkwrite(mapping->host, vmf, ret);
 	return ret;
 }
@@ -1768,17 +1854,12 @@ vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf,
 {
 	int err;
 	loff_t start = ((loff_t)vmf->pgoff) << PAGE_SHIFT;
-	size_t len = 0;
+	unsigned int order = pe_order(pe_size);
+	size_t len = PAGE_SIZE << order;
 
-	if (pe_size == PE_SIZE_PTE)
-		len = PAGE_SIZE;
-	else if (pe_size == PE_SIZE_PMD)
-		len = PMD_SIZE;
-	else
-		WARN_ON_ONCE(1);
 	err = vfs_fsync_range(vmf->vma->vm_file, start, start + len - 1, 1);
 	if (err)
 		return VM_FAULT_SIGBUS;
-	return dax_insert_pfn_mkwrite(vmf, pe_size, pfn);
+	return dax_insert_pfn_mkwrite(vmf, pfn, order);
 }
 EXPORT_SYMBOL_GPL(dax_finish_sync_fault);
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 65/74] dax: Convert dax_layout_busy_page to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (63 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 64/74] dax: Convert dax_insert_pfn_mkwrite to XArray Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 66/74] dax: Convert __dax_invalidate_entry " Matthew Wilcox
                   ` (9 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Instead of using a pagevec, just use the XArray iterators.  Add a
conditional rescheduling point which probably should have been there in
the original.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 fs/dax.c | 57 +++++++++++++++++++++-----------------------------------
 1 file changed, 21 insertions(+), 36 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 71181f4bb1d3..7b80b17cba50 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -697,11 +697,10 @@ static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index,
  */
 struct page *dax_layout_busy_page(struct address_space *mapping)
 {
-	pgoff_t	indices[PAGEVEC_SIZE];
+	XA_STATE(xas, &mapping->i_pages, 0);
+	void *entry;
+	unsigned int scanned = 0;
 	struct page *page = NULL;
-	struct pagevec pvec;
-	pgoff_t	index, end;
-	unsigned i;
 
 	/*
 	 * In the 'limited' case get_user_pages() for dax is disabled.
@@ -712,13 +711,9 @@ struct page *dax_layout_busy_page(struct address_space *mapping)
 	if (!dax_mapping(mapping) || !mapping_mapped(mapping))
 		return NULL;
 
-	pagevec_init(&pvec);
-	index = 0;
-	end = -1;
-
 	/*
 	 * If we race get_user_pages_fast() here either we'll see the
-	 * elevated page count in the pagevec_lookup and wait, or
+	 * elevated page count in the iteration and wait, or
 	 * get_user_pages_fast() will see that the page it took a reference
 	 * against is no longer mapped in the page tables and bail to the
 	 * get_user_pages() slow path.  The slow path is protected by
@@ -730,36 +725,26 @@ struct page *dax_layout_busy_page(struct address_space *mapping)
 	 */
 	unmap_mapping_range(mapping, 0, 0, 1);
 
-	while (index < end && pagevec_lookup_entries(&pvec, mapping, index,
-				min(end - index, (pgoff_t)PAGEVEC_SIZE),
-				indices)) {
-		for (i = 0; i < pagevec_count(&pvec); i++) {
-			struct page *pvec_ent = pvec.pages[i];
-			void *entry;
-
-			index = indices[i];
-			if (index >= end)
-				break;
-
-			if (!xa_is_value(pvec_ent))
-				continue;
-
-			xa_lock_irq(&mapping->i_pages);
-			entry = get_unlocked_mapping_entry(mapping, index, NULL);
-			if (entry)
-				page = dax_busy_page(entry);
-			put_unlocked_mapping_entry(mapping, index, entry);
-			xa_unlock_irq(&mapping->i_pages);
-			if (page)
-				break;
-		}
-		pagevec_remove_exceptionals(&pvec);
-		pagevec_release(&pvec);
-		index++;
-
+	xas_lock_irq(&xas);
+	xas_for_each(&xas, entry, ULONG_MAX) {
+		if (!xa_is_value(entry))
+			continue;
+		if (unlikely(dax_is_locked(entry)))
+			entry = get_unlocked_entry(&xas);
+		if (entry)
+			page = dax_busy_page(entry);
+		put_unlocked_entry(&xas, entry);
 		if (page)
 			break;
+		if (++scanned % XA_CHECK_SCHED)
+			continue;
+
+		xas_pause(&xas);
+		xas_unlock_irq(&xas);
+		cond_resched();
+		xas_lock_irq(&xas);
 	}
+	xas_unlock_irq(&xas);
 	return page;
 }
 EXPORT_SYMBOL_GPL(dax_layout_busy_page);
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 66/74] dax: Convert __dax_invalidate_entry to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (64 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 65/74] dax: Convert dax_layout_busy_page " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 67/74] dax: Convert dax writeback " Matthew Wilcox
                   ` (8 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Avoids walking the radix tree multiple times looking for tags.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 fs/dax.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 7b80b17cba50..fe5cc4470d99 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -752,27 +752,28 @@ EXPORT_SYMBOL_GPL(dax_layout_busy_page);
 static int __dax_invalidate_entry(struct address_space *mapping,
 					  pgoff_t index, bool trunc)
 {
+	XA_STATE(xas, &mapping->i_pages, index);
 	int ret = 0;
 	void *entry;
-	struct radix_tree_root *pages = &mapping->i_pages;
 
-	xa_lock_irq(pages);
-	entry = get_unlocked_mapping_entry(mapping, index, NULL);
+	xas_lock_irq(&xas);
+	entry = get_unlocked_entry(&xas);
 	if (!entry || WARN_ON_ONCE(!xa_is_value(entry)))
 		goto out;
 	if (!trunc &&
-	    (radix_tree_tag_get(pages, index, PAGECACHE_TAG_DIRTY) ||
-	     radix_tree_tag_get(pages, index, PAGECACHE_TAG_TOWRITE)))
+	    (xas_get_tag(&xas, PAGECACHE_TAG_DIRTY) ||
+	     xas_get_tag(&xas, PAGECACHE_TAG_TOWRITE)))
 		goto out;
 	dax_disassociate_entry(entry, mapping, trunc);
-	radix_tree_delete(pages, index);
+	xas_store(&xas, NULL);
 	mapping->nrexceptional--;
 	ret = 1;
 out:
-	put_unlocked_mapping_entry(mapping, index, entry);
-	xa_unlock_irq(pages);
+	put_unlocked_entry(&xas, entry);
+	xas_unlock_irq(&xas);
 	return ret;
 }
+
 /*
  * Delete DAX entry at @index from @mapping.  Wait for it
  * to be unlocked before deleting it.
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 67/74] dax: Convert dax writeback to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (65 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 66/74] dax: Convert __dax_invalidate_entry " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 68/74] dax: Convert dax_lock_page " Matthew Wilcox
                   ` (7 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Use XArray iteration instead of a pagevec.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 fs/dax.c | 130 ++++++++++++++++++++++++++-----------------------------
 1 file changed, 62 insertions(+), 68 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index fe5cc4470d99..08595ffde566 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -973,11 +973,9 @@ static void dax_entry_mkclean(struct address_space *mapping, pgoff_t index,
 	i_mmap_unlock_read(mapping);
 }
 
-static int dax_writeback_one(struct dax_device *dax_dev,
-		struct address_space *mapping, pgoff_t index, void *entry)
+static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev,
+		struct address_space *mapping, void *entry)
 {
-	struct radix_tree_root *pages = &mapping->i_pages;
-	void *entry2, **slot;
 	unsigned long pfn;
 	long ret = 0;
 	size_t size;
@@ -989,29 +987,35 @@ static int dax_writeback_one(struct dax_device *dax_dev,
 	if (WARN_ON(!xa_is_value(entry)))
 		return -EIO;
 
-	xa_lock_irq(pages);
-	entry2 = get_unlocked_mapping_entry(mapping, index, &slot);
-	/* Entry got punched out / reallocated? */
-	if (!entry2 || WARN_ON_ONCE(!xa_is_value(entry2)))
-		goto put_unlocked;
-	/*
-	 * Entry got reallocated elsewhere? No need to writeback. We have to
-	 * compare pfns as we must not bail out due to difference in lockbit
-	 * or entry type.
-	 */
-	if (dax_to_pfn(entry2) != dax_to_pfn(entry))
-		goto put_unlocked;
-	if (WARN_ON_ONCE(dax_is_empty_entry(entry) ||
-				dax_is_zero_entry(entry))) {
-		ret = -EIO;
-		goto put_unlocked;
+	if (unlikely(dax_is_locked(entry))) {
+		void *old_entry = entry;
+
+		entry = get_unlocked_entry(xas);
+
+		/* Entry got punched out / reallocated? */
+		if (!entry || WARN_ON_ONCE(!xa_is_value(entry)))
+			goto put_unlocked;
+		/*
+		 * Entry got reallocated elsewhere? No need to writeback.
+		 * We have to compare pfns as we must not bail out due to
+		 * difference in lockbit or entry type.
+		 */
+		if (dax_to_pfn(old_entry) != dax_to_pfn(entry))
+			goto put_unlocked;
+		if (WARN_ON_ONCE(dax_is_empty_entry(entry) ||
+					dax_is_zero_entry(entry))) {
+			ret = -EIO;
+			goto put_unlocked;
+		}
+
+		/* Another fsync thread may have already done this entry */
+		if (!xas_get_tag(xas, PAGECACHE_TAG_TOWRITE))
+			goto put_unlocked;
 	}
 
-	/* Another fsync thread may have already written back this entry */
-	if (!radix_tree_tag_get(pages, index, PAGECACHE_TAG_TOWRITE))
-		goto put_unlocked;
 	/* Lock the entry to serialize with page faults */
-	entry = lock_slot(mapping, slot);
+	dax_lock_entry(xas, entry);
+
 	/*
 	 * We can clear the tag now but we have to be careful so that concurrent
 	 * dax_writeback_one() calls for the same index cannot finish before we
@@ -1019,8 +1023,8 @@ static int dax_writeback_one(struct dax_device *dax_dev,
 	 * at the entry only under the i_pages lock and once they do that
 	 * they will see the entry locked and wait for it to unlock.
 	 */
-	radix_tree_tag_clear(pages, index, PAGECACHE_TAG_TOWRITE);
-	xa_unlock_irq(pages);
+	xas_clear_tag(xas, PAGECACHE_TAG_TOWRITE);
+	xas_unlock_irq(xas);
 
 	/*
 	 * Even if dax_writeback_mapping_range() was given a wbc->range_start
@@ -1032,7 +1036,7 @@ static int dax_writeback_one(struct dax_device *dax_dev,
 	pfn = dax_to_pfn(entry);
 	size = PAGE_SIZE << dax_entry_order(entry);
 
-	dax_entry_mkclean(mapping, index, pfn);
+	dax_entry_mkclean(mapping, xas->xa_index, pfn);
 	dax_flush(dax_dev, page_address(pfn_to_page(pfn)), size);
 	/*
 	 * After we have flushed the cache, we can clear the dirty tag. There
@@ -1040,16 +1044,18 @@ static int dax_writeback_one(struct dax_device *dax_dev,
 	 * the pfn mappings are writeprotected and fault waits for mapping
 	 * entry lock.
 	 */
-	xa_lock_irq(pages);
-	radix_tree_tag_clear(pages, index, PAGECACHE_TAG_DIRTY);
-	xa_unlock_irq(pages);
-	trace_dax_writeback_one(mapping->host, index, size >> PAGE_SHIFT);
-	put_locked_mapping_entry(mapping, index);
+	xas_reset(xas);
+	xas_lock_irq(xas);
+	xas_store(xas, entry);
+	xas_clear_tag(xas, PAGECACHE_TAG_DIRTY);
+	dax_wake_entry(xas, entry, false);
+
+	trace_dax_writeback_one(mapping->host, xas->xa_index,
+			size >> PAGE_SHIFT);
 	return ret;
 
  put_unlocked:
-	put_unlocked_mapping_entry(mapping, index, entry2);
-	xa_unlock_irq(pages);
+	put_unlocked_entry(xas, entry);
 	return ret;
 }
 
@@ -1061,13 +1067,13 @@ static int dax_writeback_one(struct dax_device *dax_dev,
 int dax_writeback_mapping_range(struct address_space *mapping,
 		struct block_device *bdev, struct writeback_control *wbc)
 {
+	XA_STATE(xas, &mapping->i_pages, wbc->range_start >> PAGE_SHIFT);
 	struct inode *inode = mapping->host;
-	pgoff_t start_index, end_index;
-	pgoff_t indices[PAGEVEC_SIZE];
+	pgoff_t end_index = wbc->range_end >> PAGE_SHIFT;
 	struct dax_device *dax_dev;
-	struct pagevec pvec;
-	bool done = false;
-	int i, ret = 0;
+	void *entry;
+	int ret = 0;
+	unsigned int scanned = 0;
 
 	if (WARN_ON_ONCE(inode->i_blkbits != PAGE_SHIFT))
 		return -EIO;
@@ -1079,41 +1085,29 @@ int dax_writeback_mapping_range(struct address_space *mapping,
 	if (!dax_dev)
 		return -EIO;
 
-	start_index = wbc->range_start >> PAGE_SHIFT;
-	end_index = wbc->range_end >> PAGE_SHIFT;
-
-	trace_dax_writeback_range(inode, start_index, end_index);
-
-	tag_pages_for_writeback(mapping, start_index, end_index);
+	trace_dax_writeback_range(inode, xas.xa_index, end_index);
 
-	pagevec_init(&pvec);
-	while (!done) {
-		pvec.nr = find_get_entries_tag(mapping, start_index,
-				PAGECACHE_TAG_TOWRITE, PAGEVEC_SIZE,
-				pvec.pages, indices);
+	tag_pages_for_writeback(mapping, xas.xa_index, end_index);
 
-		if (pvec.nr == 0)
+	xas_lock_irq(&xas);
+	xas_for_each_tagged(&xas, entry, end_index, PAGECACHE_TAG_TOWRITE) {
+		ret = dax_writeback_one(&xas, dax_dev, mapping, entry);
+		if (ret < 0) {
+			mapping_set_error(mapping, ret);
 			break;
-
-		for (i = 0; i < pvec.nr; i++) {
-			if (indices[i] > end_index) {
-				done = true;
-				break;
-			}
-
-			ret = dax_writeback_one(dax_dev, mapping, indices[i],
-					pvec.pages[i]);
-			if (ret < 0) {
-				mapping_set_error(mapping, ret);
-				goto out;
-			}
 		}
-		start_index = indices[pvec.nr - 1] + 1;
+		if (++scanned % XA_CHECK_SCHED)
+			continue;
+
+		xas_pause(&xas);
+		xas_unlock_irq(&xas);
+		cond_resched();
+		xas_lock_irq(&xas);
 	}
-out:
+	xas_unlock_irq(&xas);
 	put_dax(dax_dev);
-	trace_dax_writeback_range_done(inode, start_index, end_index);
-	return (ret < 0 ? ret : 0);
+	trace_dax_writeback_range_done(inode, xas.xa_index, end_index);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(dax_writeback_mapping_range);
 
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 68/74] dax: Convert dax_lock_page to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (66 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 67/74] dax: Convert dax writeback " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-29 17:30   ` Ross Zwisler
  2018-06-17  2:00 ` [PATCH v14 69/74] dax: Convert page fault handlers " Matthew Wilcox
                   ` (6 subsequent siblings)
  74 siblings, 1 reply; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 fs/dax.c | 96 +++++++++++++++++++++++++++++---------------------------
 1 file changed, 50 insertions(+), 46 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 08595ffde566..54a01380527a 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -99,6 +99,22 @@ static void *dax_make_locked(unsigned long pfn, unsigned long flags)
 			DAX_LOCKED);
 }
 
+static unsigned long dax_is_pmd_entry(void *entry)
+{
+	return xa_to_value(entry) & DAX_PMD;
+}
+
+static void *dax_make_entry(pfn_t pfn, unsigned long flags)
+{
+	return xa_mk_value(flags | (pfn_t_to_pfn(pfn) << DAX_SHIFT));
+}
+
+static void *dax_make_page_entry(struct page *page, void *entry)
+{
+	pfn_t pfn = page_to_pfn_t(page);
+	return dax_make_entry(pfn, dax_is_pmd_entry(entry));
+}
+
 static bool dax_is_locked(void *entry)
 {
 	return xa_to_value(entry) & DAX_LOCKED;
@@ -111,11 +127,6 @@ static unsigned int dax_entry_order(void *entry)
 	return 0;
 }
 
-static int dax_is_pmd_entry(void *entry)
-{
-	return xa_to_value(entry) & DAX_PMD;
-}
-
 static int dax_is_pte_entry(void *entry)
 {
 	return !(xa_to_value(entry) & DAX_PMD);
@@ -466,78 +477,71 @@ static struct page *dax_busy_page(void *entry)
 
 struct page *dax_lock_page(unsigned long pfn)
 {
-	pgoff_t index;
-	struct inode *inode;
-	wait_queue_head_t *wq;
-	void *entry = NULL, **slot;
+	struct page *page = pfn_to_page(pfn);
+	XA_STATE(xas, NULL, 0);
+	void *entry;
 	struct address_space *mapping;
-	struct wait_exceptional_entry_queue ewait;
-	struct page *ret = NULL, *page = pfn_to_page(pfn);
 
-	rcu_read_lock();
 	for (;;) {
+		rcu_read_lock();
 		mapping = READ_ONCE(page->mapping);
 
-		if (!mapping || !IS_DAX(mapping->host))
+		if (!mapping || !IS_DAX(mapping->host)) {
+			page = NULL;
 			break;
+		}
 
 		/*
 		 * In the device-dax case there's no need to lock, a
 		 * struct dev_pagemap pin is sufficient to keep the
 		 * inode alive.
 		 */
-		inode = mapping->host;
-		if (S_ISCHR(inode->i_mode)) {
-			ret = page;
+		if (S_ISCHR(mapping->host->i_mode))
 			break;
-		}
 
-		xa_lock_irq(&mapping->i_pages);
+		xas.xa = &mapping->i_pages;
+		xas_lock_irq(&xas);
+		rcu_read_unlock();
 		if (mapping != page->mapping) {
 			xa_unlock_irq(&mapping->i_pages);
 			continue;
 		}
-		index = page->index;
-
-		init_wait(&ewait.wait);
-		ewait.wait.func = wake_exceptional_entry_func;
-
-		entry = __radix_tree_lookup(&mapping->i_pages, index, NULL,
-				&slot);
-		if (!entry || WARN_ON_ONCE(!xa_is_value(entry))) {
-			xa_unlock_irq(&mapping->i_pages);
-			break;
-		} else if (!slot_locked(mapping, slot)) {
-			lock_slot(mapping, slot);
-			ret = page;
-			xa_unlock_irq(&mapping->i_pages);
-			break;
+		xas_set(&xas, page->index);
+		entry = xas_load(&xas);
+		if (dax_is_locked(entry)) {
+			entry = get_unlocked_entry(&xas);
+			/* Did the page move while we slept? */
+			if (dax_to_pfn(entry) != pfn) {
+				xas_unlock_irq(&xas);
+				continue;
+			}
 		}
-
-		wq = dax_entry_waitqueue(&mapping->i_pages, index, entry,
-				&ewait.key);
-		prepare_to_wait_exclusive(wq, &ewait.wait,
-				TASK_UNINTERRUPTIBLE);
-		xa_unlock_irq(&mapping->i_pages);
-		rcu_read_unlock();
-		schedule();
-		finish_wait(wq, &ewait.wait);
-		rcu_read_lock();
+		dax_lock_entry(&xas, entry);
+		xas_unlock_irq(&xas);
+		goto out;
 	}
 	rcu_read_unlock();
 
+out:
 	return page;
 }
 
 void dax_unlock_page(struct page *page)
 {
 	struct address_space *mapping = page->mapping;
-	struct inode *inode = mapping->host;
+	XA_STATE(xas, &mapping->i_pages, page->index);
+	void *entry;
 
-	if (S_ISCHR(inode->i_mode))
+	if (S_ISCHR(mapping->host->i_mode))
 		return;
 
-	dax_unlock_mapping_entry(mapping, page->index);
+	xas_lock_irq(&xas);
+	entry = xas_load(&xas);
+	BUG_ON(!dax_is_locked(entry));
+	entry = dax_make_page_entry(page, entry);
+	xas_store(&xas, entry);
+	dax_wake_entry(&xas, entry, false);
+	xas_unlock_irq(&xas);
 }
 
 /*
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 69/74] dax: Convert page fault handlers to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (67 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 68/74] dax: Convert dax_lock_page " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 70/74] page cache: Finish XArray conversion Matthew Wilcox
                   ` (5 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

This is the last part of DAX to be converted to the XArray so
remove all the old helper functions.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 fs/dax.c | 392 ++++++++++++++++---------------------------------------
 1 file changed, 111 insertions(+), 281 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 54a01380527a..91f7bce6ce64 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -93,12 +93,6 @@ static unsigned long dax_to_pfn(void *entry)
 	return xa_to_value(entry) >> DAX_SHIFT;
 }
 
-static void *dax_make_locked(unsigned long pfn, unsigned long flags)
-{
-	return xa_mk_value(flags | ((unsigned long)pfn << DAX_SHIFT) |
-			DAX_LOCKED);
-}
-
 static unsigned long dax_is_pmd_entry(void *entry)
 {
 	return xa_to_value(entry) & DAX_PMD;
@@ -155,10 +149,11 @@ struct wait_exceptional_entry_queue {
 	struct exceptional_entry_key key;
 };
 
-static wait_queue_head_t *dax_entry_waitqueue(struct xarray *xa,
-		pgoff_t index, void *entry, struct exceptional_entry_key *key)
+static wait_queue_head_t *dax_entry_waitqueue(struct xa_state *xas,
+		void *entry, struct exceptional_entry_key *key)
 {
 	unsigned long hash;
+	unsigned long index = xas->xa_index;
 
 	/*
 	 * If 'entry' is a PMD, align the 'index' that we use for the wait
@@ -167,11 +162,10 @@ static wait_queue_head_t *dax_entry_waitqueue(struct xarray *xa,
 	 */
 	if (dax_is_pmd_entry(entry))
 		index &= ~PG_PMD_COLOUR;
-
-	key->xa = xa;
+	key->xa = xas->xa;
 	key->entry_start = index;
 
-	hash = hash_long((unsigned long)xa ^ index, DAX_WAIT_TABLE_BITS);
+	hash = hash_long((unsigned long)xas->xa ^ index, DAX_WAIT_TABLE_BITS);
 	return wait_table + hash;
 }
 
@@ -193,13 +187,12 @@ static int wake_exceptional_entry_func(wait_queue_entry_t *wait,
  * The important information it's conveying is whether the entry at
  * this index used to be a PMD entry.
  */
-static void dax_wake_mapping_entry_waiter(struct xarray *xa,
-		pgoff_t index, void *entry, bool wake_all)
+static void dax_wake_entry(struct xa_state *xas, void *entry, bool wake_all)
 {
 	struct exceptional_entry_key key;
 	wait_queue_head_t *wq;
 
-	wq = dax_entry_waitqueue(xa, index, entry, &key);
+	wq = dax_entry_waitqueue(xas, entry, &key);
 
 	/*
 	 * Checking for locked entry and prepare_to_wait_exclusive() happens
@@ -211,12 +204,6 @@ static void dax_wake_mapping_entry_waiter(struct xarray *xa,
 		__wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
 }
 
-static void dax_wake_entry(struct xa_state *xas, void *entry, bool wake_all)
-{
-	return dax_wake_mapping_entry_waiter(xas->xa, xas->xa_index, entry,
-								wake_all);
-}
-
 /*
  * Look up entry in page cache, wait for it to become unlocked if it
  * is a DAX entry and return it.  The caller must subsequently call
@@ -240,8 +227,7 @@ static void *get_unlocked_entry(struct xa_state *xas)
 				!dax_is_locked(entry))
 			return entry;
 
-		wq = dax_entry_waitqueue(xas->xa, xas->xa_index, entry,
-				&ewait.key);
+		wq = dax_entry_waitqueue(xas, entry, &ewait.key);
 		prepare_to_wait_exclusive(wq, &ewait.wait,
 					  TASK_UNINTERRUPTIBLE);
 		xas_unlock_irq(xas);
@@ -282,119 +268,6 @@ static void dax_lock_entry(struct xa_state *xas, void *entry)
 	xas_store(xas, xa_mk_value(v | DAX_LOCKED));
 }
 
-/*
- * Check whether the given slot is locked.  Must be called with the i_pages
- * lock held.
- */
-static inline int slot_locked(struct address_space *mapping, void **slot)
-{
-	unsigned long entry = xa_to_value(
-		radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock));
-	return entry & DAX_LOCKED;
-}
-
-/*
- * Mark the given slot as locked.  Must be called with the i_pages lock held.
- */
-static inline void *lock_slot(struct address_space *mapping, void **slot)
-{
-	unsigned long v = xa_to_value(
-		radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock));
-	void *entry = xa_mk_value(v | DAX_LOCKED);
-	radix_tree_replace_slot(&mapping->i_pages, slot, entry);
-	return entry;
-}
-
-/*
- * Mark the given slot as unlocked.  Must be called with the i_pages lock held.
- */
-static inline void *unlock_slot(struct address_space *mapping, void **slot)
-{
-	unsigned long v = xa_to_value(
-		radix_tree_deref_slot_protected(slot, &mapping->i_pages.xa_lock));
-	void *entry = xa_mk_value(v & ~DAX_LOCKED);
-	radix_tree_replace_slot(&mapping->i_pages, slot, entry);
-	return entry;
-}
-
-/*
- * Lookup entry in page cache, wait for it to become unlocked if it is
- * a DAX entry and return it. The caller must call
- * put_unlocked_mapping_entry() when he decided not to lock the entry or
- * put_locked_mapping_entry() when he locked the entry and now wants to
- * unlock it.
- *
- * Must be called with the i_pages lock held.
- */
-static void *get_unlocked_mapping_entry(struct address_space *mapping,
-					pgoff_t index, void ***slotp)
-{
-	void *entry, **slot;
-	struct wait_exceptional_entry_queue ewait;
-	wait_queue_head_t *wq;
-
-	init_wait(&ewait.wait);
-	ewait.wait.func = wake_exceptional_entry_func;
-
-	for (;;) {
-		entry = __radix_tree_lookup(&mapping->i_pages, index, NULL,
-					  &slot);
-		if (!entry ||
-		    WARN_ON_ONCE(!xa_is_value(entry)) ||
-		    !slot_locked(mapping, slot)) {
-			if (slotp)
-				*slotp = slot;
-			return entry;
-		}
-
-		wq = dax_entry_waitqueue(&mapping->i_pages, index, entry,
-				&ewait.key);
-		prepare_to_wait_exclusive(wq, &ewait.wait,
-					  TASK_UNINTERRUPTIBLE);
-		xa_unlock_irq(&mapping->i_pages);
-		schedule();
-		finish_wait(wq, &ewait.wait);
-		xa_lock_irq(&mapping->i_pages);
-	}
-}
-
-static void dax_unlock_mapping_entry(struct address_space *mapping,
-				     pgoff_t index)
-{
-	void *entry, **slot;
-
-	xa_lock_irq(&mapping->i_pages);
-	entry = __radix_tree_lookup(&mapping->i_pages, index, NULL, &slot);
-	if (WARN_ON_ONCE(!entry || !xa_is_value(entry) ||
-			 !slot_locked(mapping, slot))) {
-		xa_unlock_irq(&mapping->i_pages);
-		return;
-	}
-	unlock_slot(mapping, slot);
-	xa_unlock_irq(&mapping->i_pages);
-	dax_wake_mapping_entry_waiter(&mapping->i_pages, index, entry, false);
-}
-
-static void put_locked_mapping_entry(struct address_space *mapping,
-		pgoff_t index)
-{
-	dax_unlock_mapping_entry(mapping, index);
-}
-
-/*
- * Called when we are done with page cache entry we looked up via
- * get_unlocked_mapping_entry() and which we didn't lock in the end.
- */
-static void put_unlocked_mapping_entry(struct address_space *mapping,
-				       pgoff_t index, void *entry)
-{
-	if (!entry)
-		return;
-
-	/* We have to wake up next waiter for the page cache entry lock */
-	dax_wake_mapping_entry_waiter(&mapping->i_pages, index, entry, false);
-}
-
 static unsigned long dax_entry_size(void *entry)
 {
 	if (dax_is_zero_entry(entry))
@@ -550,9 +423,9 @@ void dax_unlock_page(struct page *page)
  * that index, add a locked empty entry.
  *
  * When requesting an entry with size DAX_PMD, grab_mapping_entry() will
- * either return that locked entry or will return an error.  This error will
- * happen if there are any 4k entries within the 2MiB range that we are
- * requesting.
+ * either return that locked entry or will return VM_FAULT_FALLBACK.
+ * This will happen if there are any 4k entries within the 2MiB range
+ * that we are requesting.
  *
  * We always favor 4k entries over 2MiB entries. There isn't a flow where we
  * evict 4k entries in order to 'upgrade' them to a 2MiB entry.  A 2MiB
@@ -568,29 +441,31 @@ void dax_unlock_page(struct page *page)
  * Note: Unlike filemap_fault() we don't honor FAULT_FLAG_RETRY flags. For
  * persistent memory the benefit is doubtful. We can add that later if we can
  * show it helps.
+ *
+ * On error, this function does not return an ERR_PTR.  Instead it returns
+ * a VM_FAULT code, encoded as an xarray internal entry.  The ERR_PTR values
+ * overlap with xarray value entries.
  */
-static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index,
-		unsigned long size_flag)
+static
+void *grab_mapping_entry(struct xa_state *xas, struct address_space *mapping)
 {
 	bool pmd_downgrade = false; /* splitting 2MiB entry into 4k entries? */
-	void *entry, **slot;
-
-restart:
-	xa_lock_irq(&mapping->i_pages);
-	entry = get_unlocked_mapping_entry(mapping, index, &slot);
-
-	if (WARN_ON_ONCE(entry && !xa_is_value(entry))) {
-		entry = ERR_PTR(-EIO);
-		goto out_unlock;
-	}
+	void *locked = dax_make_entry(pfn_to_pfn_t(0),
+						DAX_EMPTY | DAX_LOCKED);
+	void *unlocked = dax_make_entry(pfn_to_pfn_t(0), DAX_EMPTY);
+	void *entry;
 
-	if (entry) {
-		if (size_flag & DAX_PMD) {
+retry:
+	xas_lock_irq(xas);
+	xas_for_each_conflict(xas, entry) {
+		if (dax_is_locked(entry))
+			entry = get_unlocked_entry(xas);
+		if (!xa_is_value(entry))
+			goto error;
+		if (xas->xa_shift) {
 			if (dax_is_pte_entry(entry)) {
-				put_unlocked_mapping_entry(mapping, index,
-						entry);
-				entry = ERR_PTR(-EEXIST);
-				goto out_unlock;
+				put_unlocked_entry(xas, entry);
+				goto fallback;
 			}
 		} else { /* trying to grab a PTE entry */
 			if (dax_is_pmd_entry(entry) &&
@@ -599,89 +474,56 @@ static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index,
 				pmd_downgrade = true;
 			}
 		}
+		dax_lock_entry(xas, entry);
+		break;	/* We don't want to overwrite an existing entry */
 	}
 
-	/* No entry for given index? Make sure radix tree is big enough. */
-	if (!entry || pmd_downgrade) {
-		int err;
-
-		if (pmd_downgrade) {
-			/*
-			 * Make sure 'entry' remains valid while we drop
-			 * the i_pages lock.
-			 */
-			entry = lock_slot(mapping, slot);
-		}
+	if (!entry) {
+		xas_store(xas, locked);
+		if (xas_error(xas))
+			goto error;
+		entry = unlocked;
+		mapping->nrexceptional++;
+	}
 
-		xa_unlock_irq(&mapping->i_pages);
+	if (pmd_downgrade) {
 		/*
 		 * Besides huge zero pages the only other thing that gets
 		 * downgraded are empty entries which don't need to be
 		 * unmapped.
 		 */
-		if (pmd_downgrade && dax_is_zero_entry(entry))
-			unmap_mapping_pages(mapping, index & ~PG_PMD_COLOUR,
+		if (dax_is_zero_entry(entry)) {
+			xas_unlock_irq(xas);
+			unmap_mapping_pages(mapping, xas->xa_index,
 							PG_PMD_NR, false);
-
-		err = radix_tree_preload(
-				mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM);
-		if (err) {
-			if (pmd_downgrade)
-				put_locked_mapping_entry(mapping, index);
-			return ERR_PTR(err);
-		}
-		xa_lock_irq(&mapping->i_pages);
-
-		if (!entry) {
-			/*
-			 * We needed to drop the i_pages lock while calling
-			 * radix_tree_preload() and we didn't have an entry to
-			 * lock.  See if another thread inserted an entry at
-			 * our index during this time.
-			 */
-			entry = __radix_tree_lookup(&mapping->i_pages, index,
-					NULL, &slot);
-			if (entry) {
-				radix_tree_preload_end();
-				xa_unlock_irq(&mapping->i_pages);
-				goto restart;
-			}
+			xas_reset(xas);
+			xas_lock_irq(xas);
 		}
 
-		if (pmd_downgrade) {
-			dax_disassociate_entry(entry, mapping, false);
-			radix_tree_delete(&mapping->i_pages, index);
+		dax_disassociate_entry(entry, mapping, false);
+		xas_store(xas, NULL);	/* undo the PMD join */
+		xas_store(xas, locked);	/* may fail with ENOMEM */
+		dax_wake_entry(xas, entry, true);
+		if (xas_error(xas)) {
 			mapping->nrexceptional--;
-			dax_wake_mapping_entry_waiter(&mapping->i_pages,
-					index, entry, true);
+			goto error;
 		}
-
-		entry = dax_make_locked(0, size_flag | DAX_EMPTY);
-
-		err = __radix_tree_insert(&mapping->i_pages, index,
-				dax_entry_order(entry), entry);
-		radix_tree_preload_end();
-		if (err) {
-			xa_unlock_irq(&mapping->i_pages);
-			/*
-			 * Our insertion of a DAX entry failed, most likely
-			 * because we were inserting a PMD entry and it
-			 * collided with a PTE sized entry at a different
-			 * index in the PMD range.  We haven't inserted
-			 * anything into the radix tree and have no waiters to
-			 * wake.
-			 */
-			return ERR_PTR(err);
-		}
-		/* Good, we have inserted empty locked entry into the tree. */
-		mapping->nrexceptional++;
-		xa_unlock_irq(&mapping->i_pages);
-		return entry;
+		entry = unlocked;
 	}
-	entry = lock_slot(mapping, slot);
- out_unlock:
-	xa_unlock_irq(&mapping->i_pages);
+
+	xas_unlock_irq(xas);
 	return entry;
+
+fallback:
+	xas_unlock_irq(xas);
+	return xa_mk_internal(VM_FAULT_FALLBACK);
+error:
+	xas_unlock_irq(xas);
+	if (xas_nomem(xas, GFP_NOIO))
+		goto retry;
+	if (xas->xa_node == XA_ERROR(-ENOMEM))
+		return xa_mk_internal(VM_FAULT_OOM);
+	return xa_mk_internal(VM_FAULT_SIGBUS);
 }
 
 /**
@@ -840,29 +682,25 @@ static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev,
  * already in the tree, we will skip the insertion and just dirty the PMD as
  * appropriate.
  */
-static void *dax_insert_entry(struct address_space *mapping,
-		struct vm_fault *vmf,
+static void *dax_insert_entry(struct xa_state *xas,
+		struct address_space *mapping, struct vm_fault *vmf,
 		void *entry, pfn_t pfn_t, unsigned long flags, bool dirty)
 {
-	struct radix_tree_root *pages = &mapping->i_pages;
-	unsigned long pfn = pfn_t_to_pfn(pfn_t);
-	pgoff_t index = vmf->pgoff;
-	void *new_entry;
-
+	void *new_entry = dax_make_entry(pfn_t, flags);
 	if (dirty)
 		__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
 
 	if (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE)) {
+		unsigned long index = xas->xa_index;
 		/* we are replacing a zero page with block mapping */
 		if (dax_is_pmd_entry(entry))
-			unmap_mapping_pages(mapping, index & ~PG_PMD_COLOUR,
-							PG_PMD_NR, false);
+			unmap_mapping_pages(mapping, index, PG_PMD_NR, false);
 		else /* pte entry */
-			unmap_mapping_pages(mapping, vmf->pgoff, 1, false);
+			unmap_mapping_pages(mapping, index, 1, false);
 	}
 
-	xa_lock_irq(pages);
-	new_entry = dax_make_locked(pfn, flags);
+	xas_reset(xas);
+	xas_lock_irq(xas);
 	if (dax_entry_size(entry) != dax_entry_size(new_entry)) {
 		dax_disassociate_entry(entry, mapping, false);
 		dax_associate_entry(new_entry, mapping, vmf->vma, vmf->address);
@@ -877,21 +715,16 @@ static void *dax_insert_entry(struct address_space *mapping,
 		 * existing entry is a PMD, we will just leave the PMD in the
 		 * tree and dirty it if necessary.
 		 */
-		struct radix_tree_node *node;
-		void **slot;
-		void *ret;
-
-		ret = __radix_tree_lookup(pages, index, &node, &slot);
-		WARN_ON_ONCE(ret != entry);
-		__radix_tree_replace(pages, node, slot,
-				     new_entry, NULL);
+		dax_lock_entry(xas, new_entry);
 		entry = new_entry;
 	}
 
-	if (dirty)
-		radix_tree_tag_set(pages, index, PAGECACHE_TAG_DIRTY);
+	if (dirty) {
+		xas_load(xas);	/* Walk the xa_state */
+		xas_set_tag(xas, PAGECACHE_TAG_DIRTY);
+	}
 
-	xa_unlock_irq(pages);
+	xas_unlock_irq(xas);
 	return entry;
 }
 
@@ -1160,15 +993,16 @@ static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size,
  * If this page is ever written to we will re-fault and change the mapping to
  * point to real DAX storage instead.
  */
-static vm_fault_t dax_load_hole(struct address_space *mapping, void *entry,
-			 struct vm_fault *vmf)
+static vm_fault_t dax_load_hole(struct xa_state *xas,
+		struct address_space *mapping, void **entry,
+		struct vm_fault *vmf)
 {
 	struct inode *inode = mapping->host;
 	unsigned long vaddr = vmf->address;
 	pfn_t pfn = pfn_to_pfn_t(my_zero_pfn(vaddr));
 	vm_fault_t ret;
 
-	dax_insert_entry(mapping, vmf, entry, pfn,
+	*entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn,
 			DAX_ZERO_PAGE, false);
 
 	ret = vmf_insert_mixed(vmf->vma, vaddr, pfn);
@@ -1381,6 +1215,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct address_space *mapping = vma->vm_file->f_mapping;
+	XA_STATE(xas, &mapping->i_pages, vmf->pgoff);
 	struct inode *inode = mapping->host;
 	unsigned long vaddr = vmf->address;
 	loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT;
@@ -1407,9 +1242,9 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	if (write && !vmf->cow_page)
 		flags |= IOMAP_WRITE;
 
-	entry = grab_mapping_entry(mapping, vmf->pgoff, 0);
-	if (IS_ERR(entry)) {
-		ret = dax_fault_return(PTR_ERR(entry));
+	entry = grab_mapping_entry(&xas, mapping);
+	if (xa_is_internal(entry)) {
+		ret = xa_to_internal(entry);
 		goto out;
 	}
 
@@ -1482,7 +1317,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
 		if (error < 0)
 			goto error_finish_iomap;
 
-		entry = dax_insert_entry(mapping, vmf, entry, pfn,
+		entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn,
 						 0, write && !sync);
 
 		/*
@@ -1510,7 +1345,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	case IOMAP_UNWRITTEN:
 	case IOMAP_HOLE:
 		if (!write) {
-			ret = dax_load_hole(mapping, entry, vmf);
+			ret = dax_load_hole(&xas, mapping, &entry, vmf);
 			goto finish_iomap;
 		}
 		/*FALLTHRU*/
@@ -1537,21 +1372,20 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
 		ops->iomap_end(inode, pos, PAGE_SIZE, copied, flags, &iomap);
 	}
  unlock_entry:
-	put_locked_mapping_entry(mapping, vmf->pgoff);
+	put_locked_entry(&xas, entry);
  out:
 	trace_dax_pte_fault_done(inode, vmf, ret);
 	return ret | major;
 }
 
 #ifdef CONFIG_FS_DAX_PMD
-static vm_fault_t dax_pmd_load_hole(struct vm_fault *vmf, struct iomap *iomap,
-		void *entry)
+static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
+		struct iomap *iomap, void **entry)
 {
 	struct address_space *mapping = vmf->vma->vm_file->f_mapping;
 	unsigned long pmd_addr = vmf->address & PMD_MASK;
 	struct inode *inode = mapping->host;
 	struct page *zero_page;
-	void *ret = NULL;
 	spinlock_t *ptl;
 	pmd_t pmd_entry;
 	pfn_t pfn;
@@ -1562,7 +1396,7 @@ static vm_fault_t dax_pmd_load_hole(struct vm_fault *vmf, struct iomap *iomap,
 		goto fallback;
 
 	pfn = page_to_pfn_t(zero_page);
-	ret = dax_insert_entry(mapping, vmf, entry, pfn,
+	*entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn,
 			DAX_PMD | DAX_ZERO_PAGE, false);
 
 	ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
@@ -1575,11 +1409,11 @@ static vm_fault_t dax_pmd_load_hole(struct vm_fault *vmf, struct iomap *iomap,
 	pmd_entry = pmd_mkhuge(pmd_entry);
 	set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry);
 	spin_unlock(ptl);
-	trace_dax_pmd_load_hole(inode, vmf, zero_page, ret);
+	trace_dax_pmd_load_hole(inode, vmf, zero_page, *entry);
 	return VM_FAULT_NOPAGE;
 
 fallback:
-	trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, ret);
+	trace_dax_pmd_load_hole_fallback(inode, vmf, zero_page, *entry);
 	return VM_FAULT_FALLBACK;
 }
 
@@ -1588,6 +1422,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct address_space *mapping = vma->vm_file->f_mapping;
+	XA_STATE_ORDER(xas, &mapping->i_pages, vmf->pgoff, PMD_ORDER);
 	unsigned long pmd_addr = vmf->address & PMD_MASK;
 	bool write = vmf->flags & FAULT_FLAG_WRITE;
 	bool sync;
@@ -1595,7 +1430,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	struct inode *inode = mapping->host;
 	vm_fault_t result = VM_FAULT_FALLBACK;
 	struct iomap iomap = { 0 };
-	pgoff_t max_pgoff, pgoff;
+	pgoff_t max_pgoff;
 	void *entry;
 	loff_t pos;
 	int error;
@@ -1606,7 +1441,6 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	 * supposed to hold locks serializing us with truncate / punch hole so
 	 * this is a reliable test.
 	 */
-	pgoff = linear_page_index(vma, pmd_addr);
 	max_pgoff = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
 
 	trace_dax_pmd_fault(inode, vmf, max_pgoff, 0);
@@ -1631,24 +1465,21 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	if ((pmd_addr + PMD_SIZE) > vma->vm_end)
 		goto fallback;
 
-	if (pgoff >= max_pgoff) {
-		result = VM_FAULT_SIGBUS;
-		goto out;
-	}
-
 	/* If the PMD would extend beyond the file size */
-	if ((pgoff | PG_PMD_COLOUR) >= max_pgoff)
+	if ((xas.xa_index | PG_PMD_COLOUR) >= max_pgoff)
 		goto fallback;
 
 	/*
-	 * grab_mapping_entry() will make sure we get a 2MiB empty entry, a
-	 * 2MiB zero page entry or a DAX PMD.  If it can't (because a 4k page
-	 * is already in the tree, for instance), it will return -EEXIST and
-	 * we just fall back to 4k entries.
+	 * grab_mapping_entry() will make sure we get a 2MiB empty entry,
+	 * a 2MiB zero page entry or a DAX PMD.  If it can't (because a 4k
+	 * page is already in the tree, for instance), it will return
+	 * VM_FAULT_FALLBACK.
 	 */
-	entry = grab_mapping_entry(mapping, pgoff, DAX_PMD);
-	if (IS_ERR(entry))
+	entry = grab_mapping_entry(&xas, mapping);
+	if (xa_is_internal(entry)) {
+		result = xa_to_internal(entry);
 		goto fallback;
+	}
 
 	/*
 	 * It is possible, particularly with mixed reads & writes to private
@@ -1667,7 +1498,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	 * setting up a mapping, so really we're using iomap_begin() as a way
 	 * to look up our filesystem block.
 	 */
-	pos = (loff_t)pgoff << PAGE_SHIFT;
+	pos = (loff_t)xas.xa_index << PAGE_SHIFT;
 	error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap);
 	if (error)
 		goto unlock_entry;
@@ -1683,7 +1514,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 		if (error < 0)
 			goto finish_iomap;
 
-		entry = dax_insert_entry(mapping, vmf, entry, pfn,
+		entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn,
 						DAX_PMD, write && !sync);
 
 		/*
@@ -1708,7 +1539,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	case IOMAP_HOLE:
 		if (WARN_ON_ONCE(write))
 			break;
-		result = dax_pmd_load_hole(vmf, &iomap, entry);
+		result = dax_pmd_load_hole(&xas, vmf, &iomap, &entry);
 		break;
 	default:
 		WARN_ON_ONCE(1);
@@ -1731,13 +1562,12 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 				&iomap);
 	}
  unlock_entry:
-	put_locked_mapping_entry(mapping, pgoff);
+	put_locked_entry(&xas, entry);
  fallback:
 	if (result == VM_FAULT_FALLBACK) {
 		split_huge_pmd(vma, vmf->pmd, vmf->address);
 		count_vm_event(THP_FAULT_FALLBACK);
 	}
-out:
 	trace_dax_pmd_fault_done(inode, vmf, max_pgoff, result);
 	return result;
 }
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 70/74] page cache: Finish XArray conversion
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (68 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 69/74] dax: Convert page fault handlers " Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 71/74] radix tree: Remove radix_tree_update_node_t Matthew Wilcox
                   ` (4 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

With no more radix tree API users left, we can drop the GFP flags
and use xa_init() instead of INIT_RADIX_TREE().

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 fs/inode.c      | 2 +-
 mm/swap_state.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index 077a6174dfd5..8ab03bf193a4 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -349,7 +349,7 @@ EXPORT_SYMBOL(inc_nlink);
 
 static void __address_space_init_once(struct address_space *mapping)
 {
-	INIT_RADIX_TREE(&mapping->i_pages, GFP_ATOMIC | __GFP_ACCOUNT);
+	xa_init_flags(&mapping->i_pages, XA_FLAGS_LOCK_IRQ);
 	init_rwsem(&mapping->i_mmap_rwsem);
 	INIT_LIST_HEAD(&mapping->private_list);
 	spin_lock_init(&mapping->private_lock);
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 5cd42d05177e..3d813d2b5dff 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -596,7 +596,7 @@ int init_swap_address_space(unsigned int type, unsigned long nr_pages)
 		return -ENOMEM;
 	for (i = 0; i < nr; i++) {
 		space = spaces + i;
-		INIT_RADIX_TREE(&space->i_pages, GFP_ATOMIC|__GFP_NOWARN);
+		xa_init_flags(&space->i_pages, XA_FLAGS_LOCK_IRQ);
 		atomic_set(&space->i_mmap_writable, 0);
 		space->a_ops = &swap_aops;
 		/* swap cache doesn't use writeback related tags */
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 71/74] radix tree: Remove radix_tree_update_node_t
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (69 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 70/74] page cache: Finish XArray conversion Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 72/74] radix tree: Remove split/join code Matthew Wilcox
                   ` (3 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

The only user of this functionality was the workingset code, and it's
now been converted to the XArray.  Remove __radix_tree_delete_node()
entirely as it was also only used by the workingset code.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/radix-tree.h            |  7 +----
 lib/idr.c                             |  2 +-
 lib/radix-tree.c                      | 42 +++++----------------------
 tools/testing/radix-tree/multiorder.c |  2 +-
 4 files changed, 11 insertions(+), 42 deletions(-)

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 081e68b4376b..fc13c4b1afdb 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -242,17 +242,12 @@ void *__radix_tree_lookup(const struct radix_tree_root *, unsigned long index,
 void *radix_tree_lookup(const struct radix_tree_root *, unsigned long);
 void __rcu **radix_tree_lookup_slot(const struct radix_tree_root *,
 					unsigned long index);
-typedef void (*radix_tree_update_node_t)(struct radix_tree_node *);
 void __radix_tree_replace(struct radix_tree_root *, struct radix_tree_node *,
-			  void __rcu **slot, void *entry,
-			  radix_tree_update_node_t update_node);
+			  void __rcu **slot, void *entry);
 void radix_tree_iter_replace(struct radix_tree_root *,
 		const struct radix_tree_iter *, void __rcu **slot, void *entry);
 void radix_tree_replace_slot(struct radix_tree_root *,
 			     void __rcu **slot, void *entry);
-void __radix_tree_delete_node(struct radix_tree_root *,
-			      struct radix_tree_node *,
-			      radix_tree_update_node_t update_node);
 void radix_tree_iter_delete(struct radix_tree_root *,
 			struct radix_tree_iter *iter, void __rcu **slot);
 void *radix_tree_delete_item(struct radix_tree_root *, unsigned long, void *);
diff --git a/lib/idr.c b/lib/idr.c
index 0d7410d1fb7c..58b88f5eb672 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -303,7 +303,7 @@ void *idr_replace(struct idr *idr, void *ptr, unsigned long id)
 	if (!slot || radix_tree_tag_get(&idr->idr_rt, id, IDR_FREE))
 		return ERR_PTR(-ENOENT);
 
-	__radix_tree_replace(&idr->idr_rt, node, slot, ptr, NULL);
+	__radix_tree_replace(&idr->idr_rt, node, slot, ptr);
 
 	return entry;
 }
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index d0f44ea96945..001062d41f9f 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -610,8 +610,7 @@ static int radix_tree_extend(struct radix_tree_root *root, gfp_t gfp,
  *	radix_tree_shrink    -    shrink radix tree to minimum height
  *	@root		radix tree root
  */
-static inline bool radix_tree_shrink(struct radix_tree_root *root,
-				     radix_tree_update_node_t update_node)
+static inline bool radix_tree_shrink(struct radix_tree_root *root)
 {
 	bool shrunk = false;
 
@@ -671,8 +670,6 @@ static inline bool radix_tree_shrink(struct radix_tree_root *root,
 		node->count = 0;
 		if (!radix_tree_is_internal_node(child)) {
 			node->slots[0] = (void __rcu *)RADIX_TREE_RETRY;
-			if (update_node)
-				update_node(node);
 		}
 
 		WARN_ON_ONCE(!list_empty(&node->private_list));
@@ -684,8 +681,7 @@ static inline bool radix_tree_shrink(struct radix_tree_root *root,
 }
 
 static bool delete_node(struct radix_tree_root *root,
-			struct radix_tree_node *node,
-			radix_tree_update_node_t update_node)
+			struct radix_tree_node *node)
 {
 	bool deleted = false;
 
@@ -695,7 +691,7 @@ static bool delete_node(struct radix_tree_root *root,
 		if (node->count) {
 			if (node_to_entry(node) ==
 					rcu_dereference_raw(root->xa_head))
-				deleted |= radix_tree_shrink(root, update_node);
+				deleted |= radix_tree_shrink(root);
 			return deleted;
 		}
 
@@ -1100,15 +1096,13 @@ static int calculate_count(struct radix_tree_root *root,
  * @node:		pointer to tree node
  * @slot:		pointer to slot in @node
  * @item:		new item to store in the slot.
- * @update_node:	callback for changing leaf nodes
  *
  * For use with __radix_tree_lookup().  Caller must hold tree write locked
  * across slot lookup and replacement.
  */
 void __radix_tree_replace(struct radix_tree_root *root,
 			  struct radix_tree_node *node,
-			  void __rcu **slot, void *item,
-			  radix_tree_update_node_t update_node)
+			  void __rcu **slot, void *item)
 {
 	void *old = rcu_dereference_raw(*slot);
 	int values = !!xa_is_value(item) - !!xa_is_value(old);
@@ -1126,10 +1120,7 @@ void __radix_tree_replace(struct radix_tree_root *root,
 	if (!node)
 		return;
 
-	if (update_node)
-		update_node(node);
-
-	delete_node(root, node, update_node);
+	delete_node(root, node);
 }
 
 /**
@@ -1151,7 +1142,7 @@ void __radix_tree_replace(struct radix_tree_root *root,
 void radix_tree_replace_slot(struct radix_tree_root *root,
 			     void __rcu **slot, void *item)
 {
-	__radix_tree_replace(root, NULL, slot, item, NULL);
+	__radix_tree_replace(root, NULL, slot, item);
 }
 EXPORT_SYMBOL(radix_tree_replace_slot);
 
@@ -1168,7 +1159,7 @@ void radix_tree_iter_replace(struct radix_tree_root *root,
 				const struct radix_tree_iter *iter,
 				void __rcu **slot, void *item)
 {
-	__radix_tree_replace(root, iter->node, slot, item, NULL);
+	__radix_tree_replace(root, iter->node, slot, item);
 }
 
 #ifdef CONFIG_RADIX_TREE_MULTIORDER
@@ -1848,23 +1839,6 @@ radix_tree_gang_lookup_tag_slot(const struct radix_tree_root *root,
 }
 EXPORT_SYMBOL(radix_tree_gang_lookup_tag_slot);
 
-/**
- *	__radix_tree_delete_node    -    try to free node after clearing a slot
- *	@root:		radix tree root
- *	@node:		node containing @index
- *	@update_node:	callback for changing leaf nodes
- *
- *	After clearing the slot at @index in @node from radix tree
- *	rooted at @root, call this function to attempt freeing the
- *	node and shrinking the tree.
- */
-void __radix_tree_delete_node(struct radix_tree_root *root,
-			      struct radix_tree_node *node,
-			      radix_tree_update_node_t update_node)
-{
-	delete_node(root, node, update_node);
-}
-
 static bool __radix_tree_delete(struct radix_tree_root *root,
 				struct radix_tree_node *node, void __rcu **slot)
 {
@@ -1880,7 +1854,7 @@ static bool __radix_tree_delete(struct radix_tree_root *root,
 			node_tag_clear(root, node, tag, offset);
 
 	replace_slot(slot, NULL, node, -1, values);
-	return node && delete_node(root, node, NULL);
+	return node && delete_node(root, node);
 }
 
 /**
diff --git a/tools/testing/radix-tree/multiorder.c b/tools/testing/radix-tree/multiorder.c
index c659056340df..fc7d0c4e812a 100644
--- a/tools/testing/radix-tree/multiorder.c
+++ b/tools/testing/radix-tree/multiorder.c
@@ -618,7 +618,7 @@ static void multiorder_account(void)
 	__radix_tree_insert(&tree, 1 << 5, 5, xa_mk_value(5));
 	__radix_tree_lookup(&tree, 1 << 5, &node, &slot);
 	assert(node->count == node->nr_values * 2);
-	__radix_tree_replace(&tree, node, slot, NULL, NULL);
+	__radix_tree_replace(&tree, node, slot, NULL);
 	assert(node->nr_values == 0);
 
 	item_kill_tree(&tree);
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 72/74] radix tree: Remove split/join code
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (70 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 71/74] radix tree: Remove radix_tree_update_node_t Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 73/74] radix tree: Remove radix_tree_maybe_preload_order Matthew Wilcox
                   ` (2 subsequent siblings)
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

radix_tree_split and radix_tree_join were never used upstream.  Remove
them; if they're needed in future they will be replaced by XArray
equivalents.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/radix-tree.h            |   6 -
 lib/radix-tree.c                      | 171 +-----------------
 tools/testing/radix-tree/benchmark.c  |  91 ----------
 tools/testing/radix-tree/multiorder.c | 247 --------------------------
 4 files changed, 2 insertions(+), 513 deletions(-)

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index fc13c4b1afdb..b882d644cc47 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -284,12 +284,6 @@ static inline void radix_tree_preload_end(void)
 	preempt_enable();
 }
 
-int radix_tree_split_preload(unsigned old_order, unsigned new_order, gfp_t);
-int radix_tree_split(struct radix_tree_root *, unsigned long index,
-			unsigned new_order);
-int radix_tree_join(struct radix_tree_root *, unsigned long index,
-			unsigned new_order, void *);
-
 void __rcu **idr_get_free(struct radix_tree_root *root,
 			      struct radix_tree_iter *iter, gfp_t gfp,
 			      unsigned long max);
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 001062d41f9f..c472ceeb6a97 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -463,28 +463,6 @@ int radix_tree_maybe_preload(gfp_t gfp_mask)
 }
 EXPORT_SYMBOL(radix_tree_maybe_preload);
 
-#ifdef CONFIG_RADIX_TREE_MULTIORDER
-/*
- * Preload with enough objects to ensure that we can split a single entry
- * of order @old_order into many entries of size @new_order
- */
-int radix_tree_split_preload(unsigned int old_order, unsigned int new_order,
-							gfp_t gfp_mask)
-{
-	unsigned top = 1 << (old_order % RADIX_TREE_MAP_SHIFT);
-	unsigned layers = (old_order / RADIX_TREE_MAP_SHIFT) -
-				(new_order / RADIX_TREE_MAP_SHIFT);
-	unsigned nr = 0;
-
-	WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask));
-	BUG_ON(new_order >= old_order);
-
-	while (layers--)
-		nr = nr * RADIX_TREE_MAP_SIZE + 1;
-	return __radix_tree_preload(gfp_mask, top * nr);
-}
-#endif
-
 /*
  * The same as function above, but preload number of nodes required to insert
  * (1 << order) continuous naturally-aligned elements.
@@ -1152,8 +1130,8 @@ EXPORT_SYMBOL(radix_tree_replace_slot);
  * @slot:	pointer to slot
  * @item:	new item to store in the slot.
  *
- * For use with radix_tree_split() and radix_tree_for_each_slot().
- * Caller must hold tree write locked across split and replacement.
+ * For use with radix_tree_for_each_slot().
+ * Caller must hold tree write locked.
  */
 void radix_tree_iter_replace(struct radix_tree_root *root,
 				const struct radix_tree_iter *iter,
@@ -1162,151 +1140,6 @@ void radix_tree_iter_replace(struct radix_tree_root *root,
 	__radix_tree_replace(root, iter->node, slot, item);
 }
 
-#ifdef CONFIG_RADIX_TREE_MULTIORDER
-/**
- * radix_tree_join - replace multiple entries with one multiorder entry
- * @root: radix tree root
- * @index: an index inside the new entry
- * @order: order of the new entry
- * @item: new entry
- *
- * Call this function to replace several entries with one larger entry.
- * The existing entries are presumed to not need freeing as a result of
- * this call.
- *
- * The replacement entry will have all the tags set on it that were set
- * on any of the entries it is replacing.
- */
-int radix_tree_join(struct radix_tree_root *root, unsigned long index,
-			unsigned order, void *item)
-{
-	struct radix_tree_node *node;
-	void __rcu **slot;
-	int error;
-
-	BUG_ON(radix_tree_is_internal_node(item));
-
-	error = __radix_tree_create(root, index, order, &node, &slot);
-	if (!error)
-		error = insert_entries(node, slot, item, order, true);
-	if (error > 0)
-		error = 0;
-
-	return error;
-}
-
-/**
- * radix_tree_split - Split an entry into smaller entries
- * @root: radix tree root
- * @index: An index within the large entry
- * @order: Order of new entries
- *
- * Call this function as the first step in replacing a multiorder entry
- * with several entries of lower order.  After this function returns,
- * loop over the relevant portion of the tree using radix_tree_for_each_slot()
- * and call radix_tree_iter_replace() to set up each new entry.
- *
- * The tags from this entry are replicated to all the new entries.
- *
- * The radix tree should be locked against modification during the entire
- * replacement operation.  Lock-free lookups will see RADIX_TREE_RETRY which
- * should prompt RCU walkers to restart the lookup from the root.
- */
-int radix_tree_split(struct radix_tree_root *root, unsigned long index,
-				unsigned order)
-{
-	struct radix_tree_node *parent, *node, *child;
-	void __rcu **slot;
-	unsigned int offset, end;
-	unsigned n, tag, tags = 0;
-	gfp_t gfp = root_gfp_mask(root);
-
-	if (!__radix_tree_lookup(root, index, &parent, &slot))
-		return -ENOENT;
-	if (!parent)
-		return -ENOENT;
-
-	offset = get_slot_offset(parent, slot);
-
-	for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
-		if (tag_get(parent, tag, offset))
-			tags |= 1 << tag;
-
-	for (end = offset + 1; end < RADIX_TREE_MAP_SIZE; end++) {
-		if (!xa_is_sibling(rcu_dereference_raw(parent->slots[end])))
-			break;
-		for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
-			if (tags & (1 << tag))
-				tag_set(parent, tag, end);
-		/* rcu_assign_pointer ensures tags are set before RETRY */
-		rcu_assign_pointer(parent->slots[end], RADIX_TREE_RETRY);
-	}
-	rcu_assign_pointer(parent->slots[offset], RADIX_TREE_RETRY);
-	parent->nr_values -= (end - offset);
-
-	if (order == parent->shift)
-		return 0;
-	if (order > parent->shift) {
-		while (offset < end)
-			offset += insert_entries(parent, &parent->slots[offset],
-					RADIX_TREE_RETRY, order, true);
-		return 0;
-	}
-
-	node = parent;
-
-	for (;;) {
-		if (node->shift > order) {
-			child = radix_tree_node_alloc(gfp, node, root,
-					node->shift - RADIX_TREE_MAP_SHIFT,
-					offset, 0, 0);
-			if (!child)
-				goto nomem;
-			if (node != parent) {
-				node->count++;
-				rcu_assign_pointer(node->slots[offset],
-							node_to_entry(child));
-				for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
-					if (tags & (1 << tag))
-						tag_set(node, tag, offset);
-			}
-
-			node = child;
-			offset = 0;
-			continue;
-		}
-
-		n = insert_entries(node, &node->slots[offset],
-					RADIX_TREE_RETRY, order, false);
-		BUG_ON(n > RADIX_TREE_MAP_SIZE);
-
-		for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
-			if (tags & (1 << tag))
-				tag_set(node, tag, offset);
-		offset += n;
-
-		while (offset == RADIX_TREE_MAP_SIZE) {
-			if (node == parent)
-				break;
-			offset = node->offset;
-			child = node;
-			node = node->parent;
-			rcu_assign_pointer(node->slots[offset],
-						node_to_entry(child));
-			offset++;
-		}
-		if ((node == parent) && (offset == end))
-			return 0;
-	}
-
- nomem:
-	/* Shouldn't happen; did user forget to preload? */
-	/* TODO: free all the allocated nodes */
-	WARN_ON(1);
-	return -ENOMEM;
-}
-#endif
-
 static void node_tag_set(struct radix_tree_root *root,
 				struct radix_tree_node *node,
 				unsigned int tag, unsigned int offset)
diff --git a/tools/testing/radix-tree/benchmark.c b/tools/testing/radix-tree/benchmark.c
index 99c40f3ed133..35741b9c2a4a 100644
--- a/tools/testing/radix-tree/benchmark.c
+++ b/tools/testing/radix-tree/benchmark.c
@@ -146,90 +146,6 @@ static void benchmark_size(unsigned long size, unsigned long step, int order)
 	rcu_barrier();
 }
 
-static long long  __benchmark_split(unsigned long index,
-				    int old_order, int new_order)
-{
-	struct timespec start, finish;
-	long long nsec;
-	RADIX_TREE(tree, GFP_ATOMIC);
-
-	item_insert_order(&tree, index, old_order);
-
-	clock_gettime(CLOCK_MONOTONIC, &start);
-	radix_tree_split(&tree, index, new_order);
-	clock_gettime(CLOCK_MONOTONIC, &finish);
-	nsec = (finish.tv_sec - start.tv_sec) * NSEC_PER_SEC +
-	       (finish.tv_nsec - start.tv_nsec);
-
-	item_kill_tree(&tree);
-
-	return nsec;
-
-}
-
-static void benchmark_split(unsigned long size, unsigned long step)
-{
-	int i, j, idx;
-	long long nsec = 0;
-
-
-	for (idx = 0; idx < size; idx += step) {
-		for (i = 3; i < 11; i++) {
-			for (j = 0; j < i; j++) {
-				nsec += __benchmark_split(idx, i, j);
-			}
-		}
-	}
-
-	printv(2, "Size %8ld, step %8ld, split time %10lld ns\n",
-			size, step, nsec);
-
-}
-
-static long long  __benchmark_join(unsigned long index,
-			     unsigned order1, unsigned order2)
-{
-	unsigned long loc;
-	struct timespec start, finish;
-	long long nsec;
-	void *item, *item2 = item_create(index + 1, order1);
-	RADIX_TREE(tree, GFP_KERNEL);
-
-	item_insert_order(&tree, index, order2);
-	item = radix_tree_lookup(&tree, index);
-
-	clock_gettime(CLOCK_MONOTONIC, &start);
-	radix_tree_join(&tree, index + 1, order1, item2);
-	clock_gettime(CLOCK_MONOTONIC, &finish);
-	nsec = (finish.tv_sec - start.tv_sec) * NSEC_PER_SEC +
-		(finish.tv_nsec - start.tv_nsec);
-
-	loc = find_item(&tree, item);
-	if (loc == -1)
-		free(item);
-
-	item_kill_tree(&tree);
-
-	return nsec;
-}
-
-static void benchmark_join(unsigned long step)
-{
-	int i, j, idx;
-	long long nsec = 0;
-
-	for (idx = 0; idx < 1 << 10; idx += step) {
-		for (i = 1; i < 15; i++) {
-			for (j = 0; j < i; j++) {
-				nsec += __benchmark_join(idx, i, j);
-			}
-		}
-	}
-
-	printv(2, "Size %8d, step %8ld, join time %10lld ns\n",
-			1 << 10, step, nsec);
-}
-
 void benchmark(void)
 {
 	unsigned long size[] = {1 << 10, 1 << 20, 0};
@@ -247,11 +163,4 @@ void benchmark(void)
 	for (c = 0; size[c]; c++)
 		for (s = 0; step[s]; s++)
 			benchmark_size(size[c], step[s] << 9, 9);
-
-	for (c = 0; size[c]; c++)
-		for (s = 0; step[s]; s++)
-			benchmark_split(size[c], step[s]);
-
-	for (s = 0; step[s]; s++)
-		benchmark_join(step[s]);
 }
diff --git a/tools/testing/radix-tree/multiorder.c b/tools/testing/radix-tree/multiorder.c
index fc7d0c4e812a..b26b1e82d626 100644
--- a/tools/testing/radix-tree/multiorder.c
+++ b/tools/testing/radix-tree/multiorder.c
@@ -356,251 +356,6 @@ void multiorder_tagged_iteration(void)
 	item_kill_tree(&tree);
 }
 
-/*
- * Basic join checks: make sure we can't find an entry in the tree after
- * a larger entry has replaced it
- */
-static void multiorder_join1(unsigned long index,
-				unsigned order1, unsigned order2)
-{
-	unsigned long loc;
-	void *item, *item2 = item_create(index + 1, order1);
-	RADIX_TREE(tree, GFP_KERNEL);
-
-	item_insert_order(&tree, index, order2);
-	item = radix_tree_lookup(&tree, index);
-	radix_tree_join(&tree, index + 1, order1, item2);
-	loc = find_item(&tree, item);
-	if (loc == -1)
-		free(item);
-	item = radix_tree_lookup(&tree, index + 1);
-	assert(item == item2);
-	item_kill_tree(&tree);
-}
-
-/*
- * Check that the accounting of inline data entries is handled correctly
- * by joining a data entry to a normal pointer.
- */
-static void multiorder_join2(unsigned order1, unsigned order2)
-{
-	RADIX_TREE(tree, GFP_KERNEL);
-	struct radix_tree_node *node;
-	void *item1 = item_create(0, order1);
-	void *item2;
-
-	item_insert_order(&tree, 0, order2);
-	radix_tree_insert(&tree, 1 << order2, xa_mk_value(5));
-	item2 = __radix_tree_lookup(&tree, 1 << order2, &node, NULL);
-	assert(item2 == xa_mk_value(5));
-	assert(node->nr_values == 1);
-
-	item2 = radix_tree_lookup(&tree, 0);
-	free(item2);
-
-	radix_tree_join(&tree, 0, order1, item1);
-	item2 = __radix_tree_lookup(&tree, 1 << order2, &node, NULL);
-	assert(item2 == item1);
-	assert(node->nr_values == 0);
-	item_kill_tree(&tree);
-}
-
-/*
- * This test revealed an accounting bug for inline data entries at one point.
- * Nodes were being freed back into the pool with an elevated exception count
- * by radix_tree_join() and then radix_tree_split() was failing to zero the
- * count of value entries.
- */
-static void multiorder_join3(unsigned int order)
-{
-	RADIX_TREE(tree, GFP_KERNEL);
-	struct radix_tree_node *node;
-	void **slot;
-	struct radix_tree_iter iter;
-	unsigned long i;
-
-	for (i = 0; i < (1 << order); i++) {
-		radix_tree_insert(&tree, i, xa_mk_value(5));
-	}
-
-	radix_tree_join(&tree, 0, order, xa_mk_value(7));
-	rcu_barrier();
-
-	radix_tree_split(&tree, 0, 0);
-
-	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
-		radix_tree_iter_replace(&tree, &iter, slot, xa_mk_value(5));
-	}
-
-	__radix_tree_lookup(&tree, 0, &node, NULL);
-	assert(node->nr_values == node->count);
-
-	item_kill_tree(&tree);
-}
-
-static void multiorder_join(void)
-{
-	int i, j, idx;
-
-	for (idx = 0; idx < 1024; idx = idx * 2 + 3) {
-		for (i = 1; i < 15; i++) {
-			for (j = 0; j < i; j++) {
-				multiorder_join1(idx, i, j);
-			}
-		}
-	}
-
-	for (i = 1; i < 15; i++) {
-		for (j = 0; j < i; j++) {
-			multiorder_join2(i, j);
-		}
-	}
-
-	for (i = 3; i < 10; i++) {
-		multiorder_join3(i);
-	}
-}
-
-static void check_mem(unsigned old_order, unsigned new_order, unsigned alloc)
-{
-	struct radix_tree_preload *rtp = &radix_tree_preloads;
-	if (rtp->nr != 0)
-		printv(2, "split(%u %u) remaining %u\n", old_order, new_order,
-							rtp->nr);
-	/*
-	 * Can't check for equality here as some nodes may have been
-	 * RCU-freed while we ran.  But we should never finish with more
-	 * nodes allocated since they should have all been preloaded.
-	 */
-	if (nr_allocated > alloc)
-		printv(2, "split(%u %u) allocated %u %u\n", old_order, new_order,
-							alloc, nr_allocated);
-}
-
-static void __multiorder_split(int old_order, int new_order)
-{
-	RADIX_TREE(tree, GFP_ATOMIC);
-	void **slot;
-	struct radix_tree_iter iter;
-	unsigned alloc;
-	struct item *item;
-
-	radix_tree_preload(GFP_KERNEL);
-	assert(item_insert_order(&tree, 0, old_order) == 0);
-	radix_tree_preload_end();
-
-	/* Wipe out the preloaded cache or it'll confuse check_mem() */
-	radix_tree_cpu_dead(0);
-
-	item = radix_tree_tag_set(&tree, 0, 2);
-
-	radix_tree_split_preload(old_order, new_order, GFP_KERNEL);
-	alloc = nr_allocated;
-	radix_tree_split(&tree, 0, new_order);
-	check_mem(old_order, new_order, alloc);
-	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
-		radix_tree_iter_replace(&tree, &iter, slot,
-					item_create(iter.index, new_order));
-	}
-	radix_tree_preload_end();
-
-	item_kill_tree(&tree);
-	free(item);
-}
-
-static void __multiorder_split2(int old_order, int new_order)
-{
-	RADIX_TREE(tree, GFP_KERNEL);
-	void **slot;
-	struct radix_tree_iter iter;
-	struct radix_tree_node *node;
-	void *item;
-
-	__radix_tree_insert(&tree, 0, old_order, xa_mk_value(5));
-
-	item = __radix_tree_lookup(&tree, 0, &node, NULL);
-	assert(item == xa_mk_value(5));
-	assert(node->nr_values > 0);
-
-	radix_tree_split(&tree, 0, new_order);
-	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
-		radix_tree_iter_replace(&tree, &iter, slot,
-					item_create(iter.index, new_order));
-	}
-
-	item = __radix_tree_lookup(&tree, 0, &node, NULL);
-	assert(item != xa_mk_value(5));
-	assert(node->nr_values == 0);
-
-	item_kill_tree(&tree);
-}
-
-static void __multiorder_split3(int old_order, int new_order)
-{
-	RADIX_TREE(tree, GFP_KERNEL);
-	void **slot;
-	struct radix_tree_iter iter;
-	struct radix_tree_node *node;
-	void *item;
-
-	__radix_tree_insert(&tree, 0, old_order, xa_mk_value(5));
-
-	item = __radix_tree_lookup(&tree, 0, &node, NULL);
-	assert(item == xa_mk_value(5));
-	assert(node->nr_values > 0);
-
-	radix_tree_split(&tree, 0, new_order);
-	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
-		radix_tree_iter_replace(&tree, &iter, slot, xa_mk_value(7));
-	}
-
-	item = __radix_tree_lookup(&tree, 0, &node, NULL);
-	assert(item == xa_mk_value(7));
-	assert(node->nr_values > 0);
-
-	item_kill_tree(&tree);
-
-	__radix_tree_insert(&tree, 0, old_order, xa_mk_value(5));
-
-	item = __radix_tree_lookup(&tree, 0, &node, NULL);
-	assert(item == xa_mk_value(5));
-	assert(node->nr_values > 0);
-
-	radix_tree_split(&tree, 0, new_order);
-	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
-		if (iter.index == (1 << new_order))
-			radix_tree_iter_replace(&tree, &iter, slot,
-						xa_mk_value(7));
-		else
-			radix_tree_iter_replace(&tree, &iter, slot, NULL);
-	}
-
-	item = __radix_tree_lookup(&tree, 1 << new_order, &node, NULL);
-	assert(item == xa_mk_value(7));
-	assert(node->count == node->nr_values);
-	do {
-		node = node->parent;
-		if (!node)
-			break;
-		assert(node->count == 1);
-		assert(node->nr_values == 0);
-	} while (1);
-
-	item_kill_tree(&tree);
-}
-
-static void multiorder_split(void)
-{
-	int i, j;
-
-	for (i = 3; i < 11; i++)
-		for (j = 0; j < i; j++) {
-			__multiorder_split(i, j);
-			__multiorder_split2(i, j);
-			__multiorder_split3(i, j);
-		}
-}
-
 static void multiorder_account(void)
 {
 	RADIX_TREE(tree, GFP_KERNEL);
@@ -702,8 +457,6 @@ void multiorder_checks(void)
 	multiorder_tag_tests();
 	multiorder_iteration();
 	multiorder_tagged_iteration();
-	multiorder_join();
-	multiorder_split();
 	multiorder_account();
 	multiorder_iteration_race();
 
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 73/74] radix tree: Remove radix_tree_maybe_preload_order
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (71 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 72/74] radix tree: Remove split/join code Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-17  2:00 ` [PATCH v14 74/74] radix tree: Remove radix_tree_clear_tags Matthew Wilcox
  2018-06-19  3:12 ` [PATCH v14 00/74] Convert page cache to XArray Ross Zwisler
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

This function was only used by the page cache which is now converted
to the XArray.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/radix-tree.h |  1 -
 lib/radix-tree.c           | 74 --------------------------------------
 2 files changed, 75 deletions(-)

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index b882d644cc47..f8ef267e4975 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -259,7 +259,6 @@ unsigned int radix_tree_gang_lookup(const struct radix_tree_root *,
 			unsigned int max_items);
 int radix_tree_preload(gfp_t gfp_mask);
 int radix_tree_maybe_preload(gfp_t gfp_mask);
-int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order);
 void radix_tree_init(void);
 void *radix_tree_tag_set(struct radix_tree_root *,
 			unsigned long index, unsigned int tag);
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index c472ceeb6a97..ad03dc0c562f 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -41,9 +41,6 @@
 #include <linux/xarray.h>
 
 
-/* Number of nodes in fully populated tree of given height */
-static unsigned long height_to_maxnodes[RADIX_TREE_MAX_PATH + 1] __read_mostly;
-
 /*
  * Radix tree node cache.
  */
@@ -463,51 +460,6 @@ int radix_tree_maybe_preload(gfp_t gfp_mask)
 }
 EXPORT_SYMBOL(radix_tree_maybe_preload);
 
-/*
- * The same as function above, but preload number of nodes required to insert
- * (1 << order) continuous naturally-aligned elements.
- */
-int radix_tree_maybe_preload_order(gfp_t gfp_mask, int order)
-{
-	unsigned long nr_subtrees;
-	int nr_nodes, subtree_height;
-
-	/* Preloading doesn't help anything with this gfp mask, skip it */
-	if (!gfpflags_allow_blocking(gfp_mask)) {
-		preempt_disable();
-		return 0;
-	}
-
-	/*
-	 * Calculate number and height of fully populated subtrees it takes to
-	 * store (1 << order) elements.
-	 */
-	nr_subtrees = 1 << order;
-	for (subtree_height = 0; nr_subtrees > RADIX_TREE_MAP_SIZE;
-			subtree_height++)
-		nr_subtrees >>= RADIX_TREE_MAP_SHIFT;
-
-	/*
-	 * The worst case is zero height tree with a single item at index 0 and
-	 * then inserting items starting at ULONG_MAX - (1 << order).
-	 *
-	 * This requires RADIX_TREE_MAX_PATH nodes to build branch from root to
-	 * 0-index item.
-	 */
-	nr_nodes = RADIX_TREE_MAX_PATH;
-
-	/* Plus branch to fully populated subtrees. */
-	nr_nodes += RADIX_TREE_MAX_PATH - subtree_height;
-
-	/* Root node is shared. */
-	nr_nodes--;
-
-	/* Plus nodes required to build subtrees. */
-	nr_nodes += nr_subtrees * height_to_maxnodes[subtree_height];
-
-	return __radix_tree_preload(gfp_mask, nr_nodes);
-}
-
 static unsigned radix_tree_load_root(const struct radix_tree_root *root,
 		struct radix_tree_node **nodep, unsigned long *maxindex)
 {
@@ -1928,31 +1880,6 @@ radix_tree_node_ctor(void *arg)
 	INIT_LIST_HEAD(&node->private_list);
 }
 
-static __init unsigned long __maxindex(unsigned int height)
-{
-	unsigned int width = height * RADIX_TREE_MAP_SHIFT;
-	int shift = RADIX_TREE_INDEX_BITS - width;
-
-	if (shift < 0)
-		return ~0UL;
-	if (shift >= BITS_PER_LONG)
-		return 0UL;
-	return ~0UL >> shift;
-}
-
-static __init void radix_tree_init_maxnodes(void)
-{
-	unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH + 1];
-	unsigned int i, j;
-
-	for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
-		height_to_maxindex[i] = __maxindex(i);
-	for (i = 0; i < ARRAY_SIZE(height_to_maxnodes); i++) {
-		for (j = i; j > 0; j--)
-			height_to_maxnodes[i] += height_to_maxindex[j - 1] + 1;
-	}
-}
-
 static int radix_tree_cpu_dead(unsigned int cpu)
 {
 	struct radix_tree_preload *rtp;
@@ -1982,7 +1909,6 @@ void __init radix_tree_init(void)
 			sizeof(struct radix_tree_node), 0,
 			SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
 			radix_tree_node_ctor);
-	radix_tree_init_maxnodes();
 	ret = cpuhp_setup_state_nocalls(CPUHP_RADIX_DEAD, "lib/radix:dead",
 					NULL, radix_tree_cpu_dead);
 	WARN_ON(ret < 0);
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH v14 74/74] radix tree: Remove radix_tree_clear_tags
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (72 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 73/74] radix tree: Remove radix_tree_maybe_preload_order Matthew Wilcox
@ 2018-06-17  2:00 ` Matthew Wilcox
  2018-06-19  3:12 ` [PATCH v14 00/74] Convert page cache to XArray Ross Zwisler
  74 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-17  2:00 UTC (permalink / raw)
  To: linux-mm, linux-fsdevel, linux-kernel
  Cc: Matthew Wilcox, Jan Kara, Jeff Layton, Lukas Czerner,
	Ross Zwisler, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

The page cache was the only user of this interface and it has now
been converted to the XArray.  Transform the test into a test of
xas_init_tags().

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/radix-tree.h           |  2 --
 lib/radix-tree.c                     | 13 -----------
 lib/test_xarray.c                    | 33 ++++++++++++++++++++++++++++
 tools/testing/radix-tree/tag_check.c | 29 ------------------------
 4 files changed, 33 insertions(+), 44 deletions(-)

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index f8ef267e4975..27c15990951d 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -252,8 +252,6 @@ void radix_tree_iter_delete(struct radix_tree_root *,
 			struct radix_tree_iter *iter, void __rcu **slot);
 void *radix_tree_delete_item(struct radix_tree_root *, unsigned long, void *);
 void *radix_tree_delete(struct radix_tree_root *, unsigned long);
-void radix_tree_clear_tags(struct radix_tree_root *, struct radix_tree_node *,
-			   void __rcu **slot);
 unsigned int radix_tree_gang_lookup(const struct radix_tree_root *,
 			void **results, unsigned long first_index,
 			unsigned int max_items);
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index ad03dc0c562f..101f1c28e1b6 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -1711,19 +1711,6 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
 }
 EXPORT_SYMBOL(radix_tree_delete);
 
-void radix_tree_clear_tags(struct radix_tree_root *root,
-			   struct radix_tree_node *node,
-			   void __rcu **slot)
-{
-	if (node) {
-		unsigned int tag, offset = get_slot_offset(node, slot);
-		for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
-			node_tag_clear(root, node, tag, offset);
-	} else {
-		root_tag_clear_all(root);
-	}
-}
-
 /**
  *	radix_tree_tagged - test whether any items in the tree are tagged
  *	@root:		radix tree root
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index 0ac0c8108ef4..98c0efdd27a0 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -170,12 +170,45 @@ static void check_xa_tag_1(struct xarray *xa, unsigned long index)
 	XA_BUG_ON(xa, !xa_empty(xa));
 }
 
+static void check_xa_tag_2(struct xarray *xa)
+{
+	XA_STATE(xas, xa, 0);
+	unsigned long index;
+	unsigned int count = 0;
+	void *entry;
+
+	xa_store_value(xa, 0, GFP_KERNEL);
+	xa_set_tag(xa, 0, XA_TAG_0);
+	xas_load(&xas);
+	xas_init_tags(&xas);
+	XA_BUG_ON(xa, !xa_get_tag(xa, 0, XA_TAG_0) == 0);
+
+	for (index = 3500; index < 4500; index++) {
+		xa_store_value(xa, index, GFP_KERNEL);
+		xa_set_tag(xa, index, XA_TAG_0);
+	}
+
+	xas_reset(&xas);
+	xas_for_each_tagged(&xas, entry, ULONG_MAX, XA_TAG_0)
+		count++;
+	XA_BUG_ON(xa, count != 1000);
+
+	xas_for_each(&xas, entry, ULONG_MAX) {
+		xas_init_tags(&xas);
+		XA_BUG_ON(xa, !xa_get_tag(xa, xas.xa_index, XA_TAG_0));
+		XA_BUG_ON(xa, !xas_get_tag(&xas, XA_TAG_0));
+	}
+
+	xa_destroy(xa);
+}
+
 static void check_xa_tag(struct xarray *xa)
 {
 	check_xa_tag_1(xa, 0);
 	check_xa_tag_1(xa, 4);
 	check_xa_tag_1(xa, 64);
 	check_xa_tag_1(xa, 4096);
+	check_xa_tag_2(xa);
 }
 
 static void check_xa_shrink(struct xarray *xa)
diff --git a/tools/testing/radix-tree/tag_check.c b/tools/testing/radix-tree/tag_check.c
index 543181e4847b..56a42f1c5ab0 100644
--- a/tools/testing/radix-tree/tag_check.c
+++ b/tools/testing/radix-tree/tag_check.c
@@ -331,34 +331,6 @@ static void single_check(void)
 	item_kill_tree(&tree);
 }
 
-void radix_tree_clear_tags_test(void)
-{
-	unsigned long index;
-	struct radix_tree_node *node;
-	struct radix_tree_iter iter;
-	void **slot;
-
-	RADIX_TREE(tree, GFP_KERNEL);
-
-	item_insert(&tree, 0);
-	item_tag_set(&tree, 0, 0);
-	__radix_tree_lookup(&tree, 0, &node, &slot);
-	radix_tree_clear_tags(&tree, node, slot);
-	assert(item_tag_get(&tree, 0, 0) == 0);
-
-	for (index = 0; index < 1000; index++) {
-		item_insert(&tree, index);
-		item_tag_set(&tree, index, 0);
-	}
-
-	radix_tree_for_each_slot(slot, &tree, &iter, 0) {
-		radix_tree_clear_tags(&tree, iter.node, slot);
-		assert(item_tag_get(&tree, iter.index, 0) == 0);
-	}
-
-	item_kill_tree(&tree);
-}
-
 void tag_check(void)
 {
 	single_check();
@@ -376,5 +348,4 @@ void tag_check(void)
 	thrash_tags();
 	rcu_barrier();
 	printv(2, "after thrash_tags: %d allocated\n", nr_allocated);
-	radix_tree_clear_tags_test();
 }
-- 
2.17.1

^ permalink raw reply	[flat|nested] 90+ messages in thread

* Re: [PATCH v14 00/74] Convert page cache to XArray
  2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
                   ` (73 preceding siblings ...)
  2018-06-17  2:00 ` [PATCH v14 74/74] radix tree: Remove radix_tree_clear_tags Matthew Wilcox
@ 2018-06-19  3:12 ` Ross Zwisler
  2018-06-19  9:22   ` Matthew Wilcox
  74 siblings, 1 reply; 90+ messages in thread
From: Ross Zwisler @ 2018-06-19  3:12 UTC (permalink / raw)
  To: Matthew Wilcox
  Cc: linux-mm, linux-fsdevel, linux-kernel, Jan Kara, Jeff Layton,
	Lukas Czerner, Ross Zwisler, Christoph Hellwig,
	Goldwyn Rodrigues, Nicholas Piggin, Ryusuke Konishi, linux-nilfs,
	Jaegeuk Kim, Chao Yu, linux-f2fs-devel

On Sat, Jun 16, 2018 at 06:59:38PM -0700, Matthew Wilcox wrote:
> The XArray is a replacement for the radix tree.  For the moment it uses
> the same data structures, enabling a gradual replacement.  This patch
> set implements the XArray and converts the page cache to use it.
> 
> A version of these patches has been running under xfstests for over
> 48 hours, so I have some confidence in them.  The DAX changes have now
> also had a reasonable test outing.  This is based on next-20180615 and
> is available as a git tree at
> git://git.infradead.org/users/willy/linux-dax.git xarray-20180615
> 
> I shall create a git branch from -rc1 and ask for that to be included in
> -next.  I'm a little concerned I still have no reviews on some of the
> later patches.
> 
> Changes since v13:
>  - Actually fixed bug in workingset conversion that led to exceptional
>    entries not being deleted from the XArray.  Not sure how I dropped
>    that patch for v13.  Thanks to David Sterba for noticing.
>  - Fixed bug in DAX writeback conversion that failed to wake up waiters.
>    Thanks to Ross for testing, and to Dan & Jeff for helping me get a
>    setup working to reproduce the problem.
>  - Converted the new dax_lock_page / dax_unlock_page functions.
>  - Moved XArray test suite entirely into the test_xarray kernel module
>    to match other test suites.  It can still be built in userspace as
>    part of the radix tree test suite.
>  - Changed email address.
>  - Moved a few functions into different patches to make the test-suite
>    additions more logical.
>  - Fixed a bug in XA_BUG_ON (oh the irony) where it evaluated the
>    condition twice.
>  - Constified xa_head() / xa_parent() / xa_entry() and their _locked
>    variants.
>  - Moved xa_parent() to xarray.h so it can be used from the workingset code.
>  - Call the xarray testsuite from the radix tree test suite to ensure
>    that I remember to run both test suites ;-)
>  - Added some more tests to the test suite.

Hit another deadlock.  This one reproduces 100% of the time in my setup with
XFS + DAX + generic/340.  It doesn't reproduce for me at all with
next-20180615.  Here's the output from "echo w > /proc/sysrq-trigger":

[   92.849119] sysrq: SysRq : Show Blocked State
[   92.850506]   task                        PC stack   pid father
[   92.852299] holetest        D    0  1651   1466 0x00000000
[   92.853912] Call Trace:
[   92.854610]  __schedule+0x2c5/0xad0
[   92.855612]  schedule+0x36/0x90
[   92.856602]  get_unlocked_entry+0xce/0x120
[   92.857756]  ? dax_insert_entry+0x2b0/0x2b0
[   92.858931]  grab_mapping_entry+0x19e/0x250
[   92.860119]  dax_iomap_pte_fault+0x115/0x1140
[   92.860836]  dax_iomap_fault+0x37/0x40
[   92.861235]  __xfs_filemap_fault+0x2de/0x310
[   92.861681]  xfs_filemap_fault+0x2c/0x30
[   92.862113]  __do_fault+0x26/0x160
[   92.862531]  __handle_mm_fault+0xc96/0x1320
[   92.863059]  handle_mm_fault+0x1ba/0x3c0
[   92.863534]  __do_page_fault+0x2b4/0x590
[   92.864029]  do_page_fault+0x38/0x2c0
[   92.864472]  do_async_page_fault+0x2c/0xb0
[   92.864985]  ? async_page_fault+0x8/0x30
[   92.865459]  async_page_fault+0x1e/0x30
[   92.865941] RIP: 0033:0x401442
[   92.866322] Code: Bad RIP value.
[   92.866739] RSP: 002b:00007fa29c9feec0 EFLAGS: 00010212
[   92.867366] RAX: 00007fa29ca00400 RBX: 0000000000001000 RCX: 0000000000008000
[   92.868219] RDX: 0000000000000009 RSI: 0000000000000000 RDI: 0000000000000000
[   92.869082] RBP: 00007fa29c9ff700 R08: 00007fa29c9ff700 R09: 00007fa29c9ff700
[   92.869939] R10: 0000000000000070 R11: 00007fa29e571ba0 R12: 00007fa29ca00000
[   92.870804] R13: 00007fffd5f24160 R14: 0000000000000400 R15: 00007fffd5f240b0

This looks very similar to the one I reported last week with generic/269.

- Ross

^ permalink raw reply	[flat|nested] 90+ messages in thread

* Re: [PATCH v14 00/74] Convert page cache to XArray
  2018-06-19  3:12 ` [PATCH v14 00/74] Convert page cache to XArray Ross Zwisler
@ 2018-06-19  9:22   ` Matthew Wilcox
  2018-06-19 16:40     ` Ross Zwisler
  0 siblings, 1 reply; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-19  9:22 UTC (permalink / raw)
  To: Ross Zwisler, linux-mm, linux-fsdevel, linux-kernel, Jan Kara,
	Jeff Layton, Lukas Czerner, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

On Mon, Jun 18, 2018 at 09:12:57PM -0600, Ross Zwisler wrote:
> Hit another deadlock.  This one reproduces 100% of the time in my setup with
> XFS + DAX + generic/340.  It doesn't reproduce for me at all with
> next-20180615.  Here's the output from "echo w > /proc/sysrq-trigger":

*sigh*.  I wonder what the differences are between our setups ...

> [   92.849119] sysrq: SysRq : Show Blocked State
> [   92.850506]   task                        PC stack   pid father
> [   92.852299] holetest        D    0  1651   1466 0x00000000
> [   92.853912] Call Trace:
> [   92.854610]  __schedule+0x2c5/0xad0
> [   92.855612]  schedule+0x36/0x90
> [   92.856602]  get_unlocked_entry+0xce/0x120
> [   92.857756]  ? dax_insert_entry+0x2b0/0x2b0
> [   92.858931]  grab_mapping_entry+0x19e/0x250
> [   92.860119]  dax_iomap_pte_fault+0x115/0x1140
> [   92.860836]  dax_iomap_fault+0x37/0x40
...
> This looks very similar to the one I reported last week with generic/269.

Yeah, another missing wakeup, no doubt.  Can you bisect this?  That was
how I found the last one; bisected it to a single patch and stared very
hard at the patch until I saw it.  I'm not going to be in a position to
tinker with my DAX setup until the first week of July.

^ permalink raw reply	[flat|nested] 90+ messages in thread

* Re: [PATCH v14 00/74] Convert page cache to XArray
  2018-06-19  9:22   ` Matthew Wilcox
@ 2018-06-19 16:40     ` Ross Zwisler
  2018-06-19 17:16       ` Matthew Wilcox
  0 siblings, 1 reply; 90+ messages in thread
From: Ross Zwisler @ 2018-06-19 16:40 UTC (permalink / raw)
  To: Matthew Wilcox
  Cc: Ross Zwisler, linux-mm, linux-fsdevel, linux-kernel, Jan Kara,
	Jeff Layton, Lukas Czerner, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

On Tue, Jun 19, 2018 at 02:22:30AM -0700, Matthew Wilcox wrote:
> On Mon, Jun 18, 2018 at 09:12:57PM -0600, Ross Zwisler wrote:
> > Hit another deadlock.  This one reproduces 100% of the time in my setup with
> > XFS + DAX + generic/340.  It doesn't reproduce for me at all with
> > next-20180615.  Here's the output from "echo w > /proc/sysrq-trigger":
> 
> *sigh*.  I wonder what the differences are between our setups ...
> 
> > [   92.849119] sysrq: SysRq : Show Blocked State
> > [   92.850506]   task                        PC stack   pid father
> > [   92.852299] holetest        D    0  1651   1466 0x00000000
> > [   92.853912] Call Trace:
> > [   92.854610]  __schedule+0x2c5/0xad0
> > [   92.855612]  schedule+0x36/0x90
> > [   92.856602]  get_unlocked_entry+0xce/0x120
> > [   92.857756]  ? dax_insert_entry+0x2b0/0x2b0
> > [   92.858931]  grab_mapping_entry+0x19e/0x250
> > [   92.860119]  dax_iomap_pte_fault+0x115/0x1140
> > [   92.860836]  dax_iomap_fault+0x37/0x40
> ...
> > This looks very similar to the one I reported last week with generic/269.
> 
> Yeah, another missing wakeup, no doubt.  Can you bisect this?  That was
> how I found the last one; bisected it to a single patch and stared very
> hard at the patch until I saw it.  I'm not going to be in a position to
> tinker with my DAX setup until the first week of July.

It bisected to this commit:

b4b4daa7e8fb0ad0fee35d3e28d00e97c849a6cb is the first bad commit
commit b4b4daa7e8fb0ad0fee35d3e28d00e97c849a6cb
Author: Matthew Wilcox <willy@infradead.org>
Date:   Thu Mar 29 22:58:27 2018 -0400

    dax: Convert page fault handlers to XArray

    This is the last part of DAX to be converted to the XArray so
    remove all the old helper functions.

    Signed-off-by: Matthew Wilcox <willy@infradead.org>

^ permalink raw reply	[flat|nested] 90+ messages in thread

* Re: [PATCH v14 00/74] Convert page cache to XArray
  2018-06-19 16:40     ` Ross Zwisler
@ 2018-06-19 17:16       ` Matthew Wilcox
  2018-06-27 11:05         ` Matthew Wilcox
  0 siblings, 1 reply; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-19 17:16 UTC (permalink / raw)
  To: Ross Zwisler, linux-mm, linux-fsdevel, linux-kernel, Jan Kara,
	Jeff Layton, Lukas Czerner, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

On Tue, Jun 19, 2018 at 10:40:37AM -0600, Ross Zwisler wrote:
> On Tue, Jun 19, 2018 at 02:22:30AM -0700, Matthew Wilcox wrote:
> > On Mon, Jun 18, 2018 at 09:12:57PM -0600, Ross Zwisler wrote:
> > > Hit another deadlock.  This one reproduces 100% of the time in my setup with
> > > XFS + DAX + generic/340.  It doesn't reproduce for me at all with
> > > next-20180615.  Here's the output from "echo w > /proc/sysrq-trigger":
> > 
> > *sigh*.  I wonder what the differences are between our setups ...
> > 
> > > [   92.849119] sysrq: SysRq : Show Blocked State
> > > [   92.850506]   task                        PC stack   pid father
> > > [   92.852299] holetest        D    0  1651   1466 0x00000000
> > > [   92.853912] Call Trace:
> > > [   92.854610]  __schedule+0x2c5/0xad0
> > > [   92.855612]  schedule+0x36/0x90
> > > [   92.856602]  get_unlocked_entry+0xce/0x120
> > > [   92.857756]  ? dax_insert_entry+0x2b0/0x2b0
> > > [   92.858931]  grab_mapping_entry+0x19e/0x250
> > > [   92.860119]  dax_iomap_pte_fault+0x115/0x1140
> > > [   92.860836]  dax_iomap_fault+0x37/0x40
> > ...
> > > This looks very similar to the one I reported last week with generic/269.
> > 
> > Yeah, another missing wakeup, no doubt.  Can you bisect this?  That was
> > how I found the last one; bisected it to a single patch and stared very
> > hard at the patch until I saw it.  I'm not going to be in a position to
> > tinker with my DAX setup until the first week of July.
> 
> It bisected to this commit:
> 
> b4b4daa7e8fb0ad0fee35d3e28d00e97c849a6cb is the first bad commit
> commit b4b4daa7e8fb0ad0fee35d3e28d00e97c849a6cb
> Author: Matthew Wilcox <willy@infradead.org>
> Date:   Thu Mar 29 22:58:27 2018 -0400
> 
>     dax: Convert page fault handlers to XArray
> 
>     This is the last part of DAX to be converted to the XArray so
>     remove all the old helper functions.
> 
>     Signed-off-by: Matthew Wilcox <willy@infradead.org>

I think I see a bug.  No idea if it's the one you're hitting ;-)

I had been intending to not use the 'entry' to decide whether we were
waiting on a 2MB or 4kB page, but rather the xas.  I shelved that idea,
but not before dropping the DAX_PMD flag being passed from the PMD
pagefault caller.  So if I put that back ...


diff --git a/fs/dax.c b/fs/dax.c
index 9919b6b545fb..75cc160d2f0b 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -367,13 +367,13 @@ static struct page *dax_busy_page(void *entry)
  * a VM_FAULT code, encoded as an xarray internal entry.  The ERR_PTR values
  * overlap with xarray value entries.
  */
-static
-void *grab_mapping_entry(struct xa_state *xas, struct address_space *mapping)
+static void *grab_mapping_entry(struct xa_state *xas,
+		struct address_space *mapping, unsigned long size)
 {
 	bool pmd_downgrade = false; /* splitting 2MiB entry into 4k entries? */
 	void *locked = dax_make_entry(pfn_to_pfn_t(0),
-						DAX_EMPTY | DAX_LOCKED);
-	void *unlocked = dax_make_entry(pfn_to_pfn_t(0), DAX_EMPTY);
+						size | DAX_EMPTY | DAX_LOCKED);
+	void *unlocked = dax_make_entry(pfn_to_pfn_t(0), size | DAX_EMPTY);
 	void *entry;
 
 retry:
@@ -1163,7 +1163,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	if (write && !vmf->cow_page)
 		flags |= IOMAP_WRITE;
 
-	entry = grab_mapping_entry(&xas, mapping);
+	entry = grab_mapping_entry(&xas, mapping, 0);
 	if (xa_is_internal(entry)) {
 		ret = xa_to_internal(entry);
 		goto out;
@@ -1396,7 +1396,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	 * page is already in the tree, for instance), it will return
 	 * VM_FAULT_FALLBACK.
 	 */
-	entry = grab_mapping_entry(&xas, mapping);
+	entry = grab_mapping_entry(&xas, mapping, DAX_PMD);
 	if (xa_is_internal(entry)) {
 		result = xa_to_internal(entry);
 		goto fallback;

^ permalink raw reply	[flat|nested] 90+ messages in thread

* Re: [PATCH v14 00/74] Convert page cache to XArray
  2018-06-19 17:16       ` Matthew Wilcox
@ 2018-06-27 11:05         ` Matthew Wilcox
  2018-06-27 19:44           ` Ross Zwisler
  0 siblings, 1 reply; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-27 11:05 UTC (permalink / raw)
  To: Ross Zwisler, linux-mm, linux-fsdevel, linux-kernel, Jan Kara,
	Jeff Layton, Lukas Czerner, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

On Tue, Jun 19, 2018 at 10:16:38AM -0700, Matthew Wilcox wrote:
> I think I see a bug.  No idea if it's the one you're hitting ;-)
> 
> I had been intending to not use the 'entry' to decide whether we were
> waiting on a 2MB or 4kB page, but rather the xas.  I shelved that idea,
> but not before dropping the DAX_PMD flag being passed from the PMD
> pagefault caller.  So if I put that back ...

Did you get a chance to test this?

> diff --git a/fs/dax.c b/fs/dax.c
> index 9919b6b545fb..75cc160d2f0b 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -367,13 +367,13 @@ static struct page *dax_busy_page(void *entry)
>   * a VM_FAULT code, encoded as an xarray internal entry.  The ERR_PTR values
>   * overlap with xarray value entries.
>   */
> -static
> -void *grab_mapping_entry(struct xa_state *xas, struct address_space *mapping)
> +static void *grab_mapping_entry(struct xa_state *xas,
> +		struct address_space *mapping, unsigned long size)
>  {
>  	bool pmd_downgrade = false; /* splitting 2MiB entry into 4k entries? */
>  	void *locked = dax_make_entry(pfn_to_pfn_t(0),
> -						DAX_EMPTY | DAX_LOCKED);
> -	void *unlocked = dax_make_entry(pfn_to_pfn_t(0), DAX_EMPTY);
> +						size | DAX_EMPTY | DAX_LOCKED);
> +	void *unlocked = dax_make_entry(pfn_to_pfn_t(0), size | DAX_EMPTY);
>  	void *entry;
>  
>  retry:
> @@ -1163,7 +1163,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
>  	if (write && !vmf->cow_page)
>  		flags |= IOMAP_WRITE;
>  
> -	entry = grab_mapping_entry(&xas, mapping);
> +	entry = grab_mapping_entry(&xas, mapping, 0);
>  	if (xa_is_internal(entry)) {
>  		ret = xa_to_internal(entry);
>  		goto out;
> @@ -1396,7 +1396,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
>  	 * page is already in the tree, for instance), it will return
>  	 * VM_FAULT_FALLBACK.
>  	 */
> -	entry = grab_mapping_entry(&xas, mapping);
> +	entry = grab_mapping_entry(&xas, mapping, DAX_PMD);
>  	if (xa_is_internal(entry)) {
>  		result = xa_to_internal(entry);
>  		goto fallback;
> 

^ permalink raw reply	[flat|nested] 90+ messages in thread

* Re: [PATCH v14 00/74] Convert page cache to XArray
  2018-06-27 11:05         ` Matthew Wilcox
@ 2018-06-27 19:44           ` Ross Zwisler
  2018-06-28  8:39             ` Matthew Wilcox
  2018-07-25 21:03             ` Matthew Wilcox
  0 siblings, 2 replies; 90+ messages in thread
From: Ross Zwisler @ 2018-06-27 19:44 UTC (permalink / raw)
  To: Matthew Wilcox
  Cc: Ross Zwisler, linux-mm, linux-fsdevel, linux-kernel, Jan Kara,
	Jeff Layton, Lukas Czerner, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

On Wed, Jun 27, 2018 at 04:05:29AM -0700, Matthew Wilcox wrote:
> On Tue, Jun 19, 2018 at 10:16:38AM -0700, Matthew Wilcox wrote:
> > I think I see a bug.  No idea if it's the one you're hitting ;-)
> > 
> > I had been intending to not use the 'entry' to decide whether we were
> > waiting on a 2MB or 4kB page, but rather the xas.  I shelved that idea,
> > but not before dropping the DAX_PMD flag being passed from the PMD
> > pagefault caller.  So if I put that back ...
> 
> Did you get a chance to test this?

With this patch it doesn't deadlock, but the test dies with a SIGBUS and we
hit a WARN_ON in the DAX code:

WARNING: CPU: 5 PID: 1678 at fs/dax.c:226 get_unlocked_entry+0xf7/0x120

I don't have a lot of time this week to debug further.  The quickest path to
victory is probably for you to get this reproducing in your test setup.  Does
XFS + DAX + generic/340 pass for you?

^ permalink raw reply	[flat|nested] 90+ messages in thread

* Re: [PATCH v14 00/74] Convert page cache to XArray
  2018-06-27 19:44           ` Ross Zwisler
@ 2018-06-28  8:39             ` Matthew Wilcox
  2018-06-28 16:30               ` Ross Zwisler
  2018-07-25 21:03             ` Matthew Wilcox
  1 sibling, 1 reply; 90+ messages in thread
From: Matthew Wilcox @ 2018-06-28  8:39 UTC (permalink / raw)
  To: Ross Zwisler, linux-mm, linux-fsdevel, linux-kernel, Jan Kara,
	Jeff Layton, Lukas Czerner, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

On Wed, Jun 27, 2018 at 01:44:38PM -0600, Ross Zwisler wrote:
> On Wed, Jun 27, 2018 at 04:05:29AM -0700, Matthew Wilcox wrote:
> > On Tue, Jun 19, 2018 at 10:16:38AM -0700, Matthew Wilcox wrote:
> > > I think I see a bug.  No idea if it's the one you're hitting ;-)
> > > 
> > > I had been intending to not use the 'entry' to decide whether we were
> > > waiting on a 2MB or 4kB page, but rather the xas.  I shelved that idea,
> > > but not before dropping the DAX_PMD flag being passed from the PMD
> > > pagefault caller.  So if I put that back ...
> > 
> > Did you get a chance to test this?
> 
> With this patch it doesn't deadlock, but the test dies with a SIGBUS and we
> hit a WARN_ON in the DAX code:
> 
> WARNING: CPU: 5 PID: 1678 at fs/dax.c:226 get_unlocked_entry+0xf7/0x120
> 
> I don't have a lot of time this week to debug further.  The quickest path to
> victory is probably for you to get this reproducing in your test setup.  Does
> XFS + DAX + generic/340 pass for you?

I won't be back in front of my test box until Tuesday, but that test
does work for me because I couldn't get your instructions to give me a
2MB aligned DAX setup.  I had to settle for 4k, so none of the 2MB stuff
has been tested properly.

^ permalink raw reply	[flat|nested] 90+ messages in thread

* Re: [PATCH v14 00/74] Convert page cache to XArray
  2018-06-28  8:39             ` Matthew Wilcox
@ 2018-06-28 16:30               ` Ross Zwisler
  0 siblings, 0 replies; 90+ messages in thread
From: Ross Zwisler @ 2018-06-28 16:30 UTC (permalink / raw)
  To: Matthew Wilcox
  Cc: Ross Zwisler, linux-mm, linux-fsdevel, linux-kernel, Jan Kara,
	Jeff Layton, Lukas Czerner, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

On Thu, Jun 28, 2018 at 01:39:09AM -0700, Matthew Wilcox wrote:
> On Wed, Jun 27, 2018 at 01:44:38PM -0600, Ross Zwisler wrote:
> > On Wed, Jun 27, 2018 at 04:05:29AM -0700, Matthew Wilcox wrote:
> > > On Tue, Jun 19, 2018 at 10:16:38AM -0700, Matthew Wilcox wrote:
> > > > I think I see a bug.  No idea if it's the one you're hitting ;-)
> > > > 
> > > > I had been intending to not use the 'entry' to decide whether we were
> > > > waiting on a 2MB or 4kB page, but rather the xas.  I shelved that idea,
> > > > but not before dropping the DAX_PMD flag being passed from the PMD
> > > > pagefault caller.  So if I put that back ...
> > > 
> > > Did you get a chance to test this?
> > 
> > With this patch it doesn't deadlock, but the test dies with a SIGBUS and we
> > hit a WARN_ON in the DAX code:
> > 
> > WARNING: CPU: 5 PID: 1678 at fs/dax.c:226 get_unlocked_entry+0xf7/0x120
> > 
> > I don't have a lot of time this week to debug further.  The quickest path to
> > victory is probably for you to get this reproducing in your test setup.  Does
> > XFS + DAX + generic/340 pass for you?
> 
> I won't be back in front of my test box until Tuesday, but that test
> does work for me because I couldn't get your instructions to give me a
> 2MB aligned DAX setup.  I had to settle for 4k, so none of the 2MB stuff
> has been tested properly.

Ah.  I've documented both my qemu setup and my filesystem setup here:

https://nvdimm.wiki.kernel.org/pmem_in_qemu
https://nvdimm.wiki.kernel.org/2mib_fs_dax

This should be enough to get you up and running in QEMU and able to reliably
get filesystem DAX PMD faults.

^ permalink raw reply	[flat|nested] 90+ messages in thread

* Re: [PATCH v14 68/74] dax: Convert dax_lock_page to XArray
  2018-06-17  2:00 ` [PATCH v14 68/74] dax: Convert dax_lock_page " Matthew Wilcox
@ 2018-06-29 17:30   ` Ross Zwisler
  2018-07-06 11:54     ` [PATCH] fs/dax: remove unused function Anders Roxell
  2018-07-06 13:04     ` [PATCH v14 68/74] dax: Convert dax_lock_page to XArray Matthew Wilcox
  0 siblings, 2 replies; 90+ messages in thread
From: Ross Zwisler @ 2018-06-29 17:30 UTC (permalink / raw)
  To: Matthew Wilcox
  Cc: linux-mm, linux-fsdevel, linux-kernel, Jan Kara, Jeff Layton,
	Lukas Czerner, Ross Zwisler, Christoph Hellwig,
	Goldwyn Rodrigues, Nicholas Piggin, Ryusuke Konishi, linux-nilfs,
	Jaegeuk Kim, Chao Yu, linux-f2fs-devel

On Sat, Jun 16, 2018 at 07:00:46PM -0700, Matthew Wilcox wrote:
> Signed-off-by: Matthew Wilcox <willy@infradead.org>
> ---
<>
> +static void *dax_make_page_entry(struct page *page, void *entry)
> +{
> +	pfn_t pfn = page_to_pfn_t(page);
> +	return dax_make_entry(pfn, dax_is_pmd_entry(entry));
> +}

This function is defined and never used, so we get:

fs/dax.c:106:14: warning: ‘dax_make_page_entry’ defined but not used [-Wunused-function]
 static void *dax_make_page_entry(struct page *page, void *entry)
  ^~~~~~~~~~~~~~~~~~~

^ permalink raw reply	[flat|nested] 90+ messages in thread

* [PATCH] fs/dax: remove unused function
  2018-06-29 17:30   ` Ross Zwisler
@ 2018-07-06 11:54     ` Anders Roxell
  2018-07-06 13:04     ` [PATCH v14 68/74] dax: Convert dax_lock_page to XArray Matthew Wilcox
  1 sibling, 0 replies; 90+ messages in thread
From: Anders Roxell @ 2018-07-06 11:54 UTC (permalink / raw)
  To: viro, willy, ross.zwisler; +Cc: linux-fsdevel, linux-kernel, Anders Roxell

When CONFIG_FS_DAX is enabled we get this warning:
fs/dax.c:106:14: warning: ‘dax_make_page_entry’ defined but not used
   [-Wunused-function]
 static void *dax_make_page_entry(struct page *page, void *entry)
              ^~~~~~~~~~~~~~~~~~~
Remove the unused function.

Fixes: 9bfcbe5ef12f ("dax: Convert dax_lock_page to XArray")
Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
---
 fs/dax.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index fcf1332dcb0a..6e6cae1db520 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -103,12 +103,6 @@ static void *dax_make_entry(pfn_t pfn, unsigned long flags)
 	return xa_mk_value(flags | (pfn_t_to_pfn(pfn) << DAX_SHIFT));
 }
 
-static void *dax_make_page_entry(struct page *page, void *entry)
-{
-	pfn_t pfn = page_to_pfn_t(page);
-	return dax_make_entry(pfn, dax_is_pmd_entry(entry));
-}
-
 static bool dax_is_locked(void *entry)
 {
 	return xa_to_value(entry) & DAX_LOCKED;
-- 
2.18.0

^ permalink raw reply	[flat|nested] 90+ messages in thread

* Re: [PATCH v14 68/74] dax: Convert dax_lock_page to XArray
  2018-06-29 17:30   ` Ross Zwisler
  2018-07-06 11:54     ` [PATCH] fs/dax: remove unused function Anders Roxell
@ 2018-07-06 13:04     ` Matthew Wilcox
  1 sibling, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-07-06 13:04 UTC (permalink / raw)
  To: Ross Zwisler, linux-mm, linux-fsdevel, linux-kernel, Jan Kara,
	Jeff Layton, Lukas Czerner, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

On Fri, Jun 29, 2018 at 11:30:55AM -0600, Ross Zwisler wrote:
> On Sat, Jun 16, 2018 at 07:00:46PM -0700, Matthew Wilcox wrote:
> > Signed-off-by: Matthew Wilcox <willy@infradead.org>
> > ---
> <>
> > +static void *dax_make_page_entry(struct page *page, void *entry)
> > +{
> > +	pfn_t pfn = page_to_pfn_t(page);
> > +	return dax_make_entry(pfn, dax_is_pmd_entry(entry));
> > +}
> 
> This function is defined and never used, so we get:
> 
> fs/dax.c:106:14: warning: ‘dax_make_page_entry’ defined but not used [-Wunused-function]
>  static void *dax_make_page_entry(struct page *page, void *entry)
>   ^~~~~~~~~~~~~~~~~~~

Yeah, it was used in one of the functions Dan added, then removed.
I understand he's planning on bringing that back before 4.19 and I'm
going to rebase on top of that, so I've left it there for now.

^ permalink raw reply	[flat|nested] 90+ messages in thread

* Re: [PATCH v14 00/74] Convert page cache to XArray
  2018-06-27 19:44           ` Ross Zwisler
  2018-06-28  8:39             ` Matthew Wilcox
@ 2018-07-25 21:03             ` Matthew Wilcox
  2018-07-25 21:12               ` Ross Zwisler
  2018-07-27 17:20               ` Ross Zwisler
  1 sibling, 2 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-07-25 21:03 UTC (permalink / raw)
  To: Ross Zwisler, linux-mm, linux-fsdevel, linux-kernel, Jan Kara,
	Jeff Layton, Lukas Czerner, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

On Wed, Jun 27, 2018 at 01:44:38PM -0600, Ross Zwisler wrote:
> On Wed, Jun 27, 2018 at 04:05:29AM -0700, Matthew Wilcox wrote:
> > On Tue, Jun 19, 2018 at 10:16:38AM -0700, Matthew Wilcox wrote:
> > > I think I see a bug.  No idea if it's the one you're hitting ;-)
> > > 
> > > I had been intending to not use the 'entry' to decide whether we were
> > > waiting on a 2MB or 4kB page, but rather the xas.  I shelved that idea,
> > > but not before dropping the DAX_PMD flag being passed from the PMD
> > > pagefault caller.  So if I put that back ...
> > 
> > Did you get a chance to test this?
> 
> With this patch it doesn't deadlock, but the test dies with a SIGBUS and we
> hit a WARN_ON in the DAX code:
> 
> WARNING: CPU: 5 PID: 1678 at fs/dax.c:226 get_unlocked_entry+0xf7/0x120
> 
> I don't have a lot of time this week to debug further.  The quickest path to
> victory is probably for you to get this reproducing in your test setup.  Does
> XFS + DAX + generic/340 pass for you?

I now have generic/340 passing.  I've pushed a new version to
git://git.infradead.org/users/willy/linux-dax.git xarray

^ permalink raw reply	[flat|nested] 90+ messages in thread

* Re: [PATCH v14 00/74] Convert page cache to XArray
  2018-07-25 21:03             ` Matthew Wilcox
@ 2018-07-25 21:12               ` Ross Zwisler
  2018-07-27 17:20               ` Ross Zwisler
  1 sibling, 0 replies; 90+ messages in thread
From: Ross Zwisler @ 2018-07-25 21:12 UTC (permalink / raw)
  To: Matthew Wilcox
  Cc: Ross Zwisler, linux-mm, linux-fsdevel, linux-kernel, Jan Kara,
	Jeff Layton, Lukas Czerner, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

On Wed, Jul 25, 2018 at 02:03:23PM -0700, Matthew Wilcox wrote:
> On Wed, Jun 27, 2018 at 01:44:38PM -0600, Ross Zwisler wrote:
> > On Wed, Jun 27, 2018 at 04:05:29AM -0700, Matthew Wilcox wrote:
> > > On Tue, Jun 19, 2018 at 10:16:38AM -0700, Matthew Wilcox wrote:
> > > > I think I see a bug.  No idea if it's the one you're hitting ;-)
> > > > 
> > > > I had been intending to not use the 'entry' to decide whether we were
> > > > waiting on a 2MB or 4kB page, but rather the xas.  I shelved that idea,
> > > > but not before dropping the DAX_PMD flag being passed from the PMD
> > > > pagefault caller.  So if I put that back ...
> > > 
> > > Did you get a chance to test this?
> > 
> > With this patch it doesn't deadlock, but the test dies with a SIGBUS and we
> > hit a WARN_ON in the DAX code:
> > 
> > WARNING: CPU: 5 PID: 1678 at fs/dax.c:226 get_unlocked_entry+0xf7/0x120
> > 
> > I don't have a lot of time this week to debug further.  The quickest path to
> > victory is probably for you to get this reproducing in your test setup.  Does
> > XFS + DAX + generic/340 pass for you?
> 
> I now have generic/340 passing.  I've pushed a new version to
> git://git.infradead.org/users/willy/linux-dax.git xarray

Thanks, I'll throw it in my test setup.

^ permalink raw reply	[flat|nested] 90+ messages in thread

* Re: [PATCH v14 00/74] Convert page cache to XArray
  2018-07-25 21:03             ` Matthew Wilcox
  2018-07-25 21:12               ` Ross Zwisler
@ 2018-07-27 17:20               ` Ross Zwisler
  2018-07-30 15:43                 ` Matthew Wilcox
  1 sibling, 1 reply; 90+ messages in thread
From: Ross Zwisler @ 2018-07-27 17:20 UTC (permalink / raw)
  To: Matthew Wilcox, zwisler
  Cc: Ross Zwisler, linux-mm, linux-fsdevel, linux-kernel, Jan Kara,
	Jeff Layton, Lukas Czerner, Christoph Hellwig, Goldwyn Rodrigues,
	Nicholas Piggin, Ryusuke Konishi, linux-nilfs, Jaegeuk Kim,
	Chao Yu, linux-f2fs-devel

On Wed, Jul 25, 2018 at 02:03:23PM -0700, Matthew Wilcox wrote:
> On Wed, Jun 27, 2018 at 01:44:38PM -0600, Ross Zwisler wrote:
> > On Wed, Jun 27, 2018 at 04:05:29AM -0700, Matthew Wilcox wrote:
> > > On Tue, Jun 19, 2018 at 10:16:38AM -0700, Matthew Wilcox wrote:
> > > > I think I see a bug.  No idea if it's the one you're hitting ;-)
> > > > 
> > > > I had been intending to not use the 'entry' to decide whether we were
> > > > waiting on a 2MB or 4kB page, but rather the xas.  I shelved that idea,
> > > > but not before dropping the DAX_PMD flag being passed from the PMD
> > > > pagefault caller.  So if I put that back ...
> > > 
> > > Did you get a chance to test this?
> > 
> > With this patch it doesn't deadlock, but the test dies with a SIGBUS and we
> > hit a WARN_ON in the DAX code:
> > 
> > WARNING: CPU: 5 PID: 1678 at fs/dax.c:226 get_unlocked_entry+0xf7/0x120
> > 
> > I don't have a lot of time this week to debug further.  The quickest path to
> > victory is probably for you to get this reproducing in your test setup.  Does
> > XFS + DAX + generic/340 pass for you?
> 
> I now have generic/340 passing.  I've pushed a new version to
> git://git.infradead.org/users/willy/linux-dax.git xarray

Okay, the next failure I'm hitting is with DAX + XFS + generic/344.  It
doesn't happen every time, but I can usually recreate it within 10 iterations
of the test.  Here's the failure:

generic/344 21s ...[ 1852.564559] run fstests generic/344 at 2018-07-27 11:19:05
[ 1853.033177] XFS (pmem0p2): Unmounting Filesystem
[ 1853.134497] XFS (pmem0p2): DAX enabled. Warning: EXPERIMENTAL, use at your own risk
[ 1853.135335] XFS (pmem0p2): Mounting V5 Filesystem
[ 1853.138119] XFS (pmem0p2): Ending clean mount
[ 1862.251185] WARNING: CPU: 10 PID: 15695 at mm/memory.c:1801 insert_pfn+0x229/0x240
[ 1862.252023] Modules linked in: dax_pmem device_dax nd_pmem nd_btt nfit libnvdimm
[ 1862.252853] CPU: 10 PID: 15695 Comm: holetest Tainted: G        W         4.18.0-rc6-00077-gc79b37ebab6d-dirty #1
[ 1862.253979] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.1-0-g0551a4be2c-prebuilt.qemu-project.org 04/01/2014
[ 1862.255232] RIP: 0010:insert_pfn+0x229/0x240
[ 1862.255734] Code: 21 fa 4c 89 4d b0 48 89 45 c0 c6 05 3c 47 74 01 01 e8 db c2 e2 ff 0f 0b 44 8b 45 ac 4c 8b 4d b0 4c 8b 55 b8 48 8b 45 c0 eb 92 <0f> 0b e9 45 fe ff ff 41 bf f4 ff ff ff e9 43 fe ff ff e8 50 c5 e2
[ 1862.257526] RSP: 0000:ffffc9000e197af8 EFLAGS: 00010216
[ 1862.257994] RAX: 0000000000002df7 RBX: ffff8800368ffe00 RCX: 0000000000000002
[ 1862.258673] RDX: 000fffffffffffff RSI: 000000000000000a RDI: 8000000002df7225
[ 1862.259319] RBP: ffffc9000e197b50 R08: 0000000000000001 R09: ffff8800b8fecd48
[ 1862.260097] R10: ffffc9000e197a30 R11: ffff88010d649a80 R12: ffff8800bb616e80
[ 1862.260843] R13: 00007fc2137c0000 R14: 00000000004521d4 R15: 00000000fffffff0
[ 1862.261563] FS:  00007fc2157ff700(0000) GS:ffff880115800000(0000) knlGS:0000000000000000
[ 1862.262420] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1862.263003] CR2: 00007fc2137c0c00 CR3: 00000000b866e000 CR4: 00000000000006e0
[ 1862.263631] Call Trace:
[ 1862.263862]  ? trace_hardirqs_on_caller+0xf4/0x190
[ 1862.264300]  __vm_insert_mixed+0x83/0xd0
[ 1862.264657]  vmf_insert_mixed_mkwrite+0x13/0x40
[ 1862.265066]  dax_iomap_pte_fault+0x760/0x1140
[ 1862.265478]  dax_iomap_fault+0x37/0x40
[ 1862.265816]  __xfs_filemap_fault+0x2de/0x310
[ 1862.266207]  xfs_filemap_page_mkwrite+0x15/0x20
[ 1862.266610]  xfs_filemap_pfn_mkwrite+0xe/0x10
[ 1862.267044]  do_wp_page+0x1bb/0x660
[ 1862.267435]  __handle_mm_fault+0xc78/0x1320
[ 1862.267912]  handle_mm_fault+0x1ba/0x3c0
[ 1862.268359]  __do_page_fault+0x2b4/0x590
[ 1862.268799]  do_page_fault+0x38/0x2c0
[ 1862.269218]  do_async_page_fault+0x2c/0xb0
[ 1862.269674]  ? async_page_fault+0x8/0x30
[ 1862.270081]  async_page_fault+0x1e/0x30
[ 1862.270431] RIP: 0033:0x401442
[ 1862.270709] Code: 1d 20 00 85 f6 0f 85 7d 00 00 00 48 85 db 7e 20 4b 8d 04 34 31 d2 66 90 48 8b 0d 21 1d 20 00 48 0f af ca 48 83 c2 01 48 39 d3 <48> 89 2c 08 75 e8 8b 0d de 1c 20 00 31 c0 85 c9 74 0a 8b 15 d6 1c
[ 1862.272811] RSP: 002b:00007fc2157feec0 EFLAGS: 00010216
[ 1862.273392] RAX: 00007fc213600c00 RBX: 0000000000001000 RCX: 00000000001c0000
[ 1862.274182] RDX: 00000000000001c1 RSI: 0000000000000000 RDI: 0000000000000001
[ 1862.274961] RBP: 00007fc2157ff700 R08: 00007fc2157ff700 R09: 00007fc2157ff700
[ 1862.275740] R10: 00007fc2157ff9d0 R11: 0000000000000202 R12: 00007fc213600000
[ 1862.276519] R13: 00007ffe07faa240 R14: 0000000000000c00 R15: 00007ffe07faa170
[ 1862.277296] irq event stamp: 13256
[ 1862.277666] hardirqs last  enabled at (13255): [<ffffffff81c8c24c>] _raw_spin_unlock_irq+0x2c/0x60
[ 1862.278630] hardirqs last disabled at (13256): [<ffffffff81e011d3>] error_entry+0x93/0x110
[ 1862.279510] softirqs last  enabled at (13250): [<ffffffff820003bf>] __do_softirq+0x3bf/0x520
[ 1862.280410] softirqs last disabled at (13229): [<ffffffff810ac388>] irq_exit+0xe8/0xf0
[ 1862.281251] ---[ end trace 4b8bc73df4e9e7ba ]---
 22s
[ 1874.258598] XFS (pmem0p2): Unmounting Filesystem
[ 1874.347182] XFS (pmem0p2): DAX enabled. Warning: EXPERIMENTAL, use at your own risk
[ 1874.348721] XFS (pmem0p2): Mounting V5 Filesystem
[ 1874.353946] XFS (pmem0p2): Ending clean mount
_check_dmesg: something found in dmesg (see /root/xfstests/results//generic/344.dmesg)
Ran: generic/344
Failures: generic/344
Failed 1 of 1 tests

- Ross

^ permalink raw reply	[flat|nested] 90+ messages in thread

* Re: [PATCH v14 00/74] Convert page cache to XArray
  2018-07-27 17:20               ` Ross Zwisler
@ 2018-07-30 15:43                 ` Matthew Wilcox
  0 siblings, 0 replies; 90+ messages in thread
From: Matthew Wilcox @ 2018-07-30 15:43 UTC (permalink / raw)
  To: Ross Zwisler, zwisler, linux-mm, linux-fsdevel, linux-kernel,
	Jan Kara, Jeff Layton, Lukas Czerner, Christoph Hellwig,
	Goldwyn Rodrigues, Nicholas Piggin, Ryusuke Konishi, linux-nilfs,
	Jaegeuk Kim, Chao Yu, linux-f2fs-devel

On Fri, Jul 27, 2018 at 11:20:35AM -0600, Ross Zwisler wrote:
> Okay, the next failure I'm hitting is with DAX + XFS + generic/344.  It
> doesn't happen every time, but I can usually recreate it within 10 iterations
> of the test.  Here's the failure:

Thanks.  I've made some progress with this; the WARNing is coming from
a vm_insert_* mkwrite call.  Inserting sufficient debugging code has
let me determine we still have a zero_pfn in the page table when we're
trying to insert a new PFN.

^ permalink raw reply	[flat|nested] 90+ messages in thread

end of thread, other threads:[~2018-07-30 15:43 UTC | newest]

Thread overview: 90+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-06-17  1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 01/74] Update email address Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 02/74] radix tree test suite: Enable ubsan Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 03/74] dax: Fix use of zero page Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 04/74] xarray: Replace exceptional entries Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 05/74] xarray: Change definition of sibling entries Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 06/74] xarray: Add definition of struct xarray Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 07/74] xarray: Define struct xa_node Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 08/74] xarray: Add documentation Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 09/74] xarray: Add XArray load operation Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 10/74] xarray: Add XArray tags Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 11/74] xarray: Add XArray unconditional store operations Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 12/74] xarray: Add XArray conditional " Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 13/74] xarray: Add XArray iterators Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 14/74] xarray: Extract entries from an XArray Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 15/74] xarray: Destroy " Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 16/74] xarray: Step through " Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 17/74] xarray: Add xas_for_each_conflict Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 18/74] xarray: Add xas_create_range Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 19/74] xarray: Add MAINTAINERS entry Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 20/74] page cache: Rearrange address_space Matthew Wilcox
2018-06-17  1:59 ` [PATCH v14 21/74] page cache: Convert hole search to XArray Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 22/74] page cache: Add and replace pages using the XArray Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 23/74] page cache: Convert page deletion to XArray Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 24/74] page cache: Convert find_get_entry " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 25/74] page cache: Convert find_get_entries " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 26/74] page cache: Convert find_get_pages_range " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 27/74] page cache: Convert find_get_pages_contig " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 28/74] page cache; Convert find_get_pages_range_tag " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 29/74] page cache: Convert find_get_entries_tag " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 30/74] page cache: Convert filemap_map_pages " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 31/74] radix tree test suite: Convert regression1 " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 32/74] page cache: Convert delete_batch " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 33/74] page cache: Remove stray radix comment Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 34/74] page cache: Convert filemap_range_has_page to XArray Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 35/74] mm: Convert page-writeback " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 36/74] mm: Convert workingset " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 37/74] mm: Convert truncate " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 38/74] mm: Convert add_to_swap_cache " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 39/74] mm: Convert delete_from_swap_cache " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 40/74] mm: Convert __do_page_cache_readahead " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 41/74] mm: Convert page migration " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 42/74] mm: Convert huge_memory " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 43/74] mm: Convert collapse_shmem " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 44/74] mm: Convert khugepaged_scan_shmem " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 45/74] mm: Convert is_page_cache_freeable " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 46/74] pagevec: Use xa_tag_t Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 47/74] shmem: Convert shmem_radix_tree_replace to XArray Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 48/74] shmem: Convert shmem_confirm_swap " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 49/74] shmem: Convert find_swap_entry " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 50/74] shmem: Convert shmem_add_to_page_cache " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 51/74] shmem: Convert shmem_alloc_hugepage " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 52/74] shmem: Convert shmem_free_swap " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 53/74] shmem: Convert shmem_partial_swap_usage " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 54/74] memfd: Convert memfd_wait_for_pins " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 55/74] memfd: Convert memfd_tag_pins " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 56/74] shmem: Comment fixups Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 57/74] btrfs: Convert page cache to XArray Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 58/74] fs: Convert buffer " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 59/74] fs: Convert writeback " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 60/74] nilfs2: Convert " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 61/74] f2fs: " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 62/74] dax: Rename some functions Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 63/74] dax: Hash on XArray instead of mapping Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 64/74] dax: Convert dax_insert_pfn_mkwrite to XArray Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 65/74] dax: Convert dax_layout_busy_page " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 66/74] dax: Convert __dax_invalidate_entry " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 67/74] dax: Convert dax writeback " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 68/74] dax: Convert dax_lock_page " Matthew Wilcox
2018-06-29 17:30   ` Ross Zwisler
2018-07-06 11:54     ` [PATCH] fs/dax: remove unused function Anders Roxell
2018-07-06 13:04     ` [PATCH v14 68/74] dax: Convert dax_lock_page to XArray Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 69/74] dax: Convert page fault handlers " Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 70/74] page cache: Finish XArray conversion Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 71/74] radix tree: Remove radix_tree_update_node_t Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 72/74] radix tree: Remove split/join code Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 73/74] radix tree: Remove radix_tree_maybe_preload_order Matthew Wilcox
2018-06-17  2:00 ` [PATCH v14 74/74] radix tree: Remove radix_tree_clear_tags Matthew Wilcox
2018-06-19  3:12 ` [PATCH v14 00/74] Convert page cache to XArray Ross Zwisler
2018-06-19  9:22   ` Matthew Wilcox
2018-06-19 16:40     ` Ross Zwisler
2018-06-19 17:16       ` Matthew Wilcox
2018-06-27 11:05         ` Matthew Wilcox
2018-06-27 19:44           ` Ross Zwisler
2018-06-28  8:39             ` Matthew Wilcox
2018-06-28 16:30               ` Ross Zwisler
2018-07-25 21:03             ` Matthew Wilcox
2018-07-25 21:12               ` Ross Zwisler
2018-07-27 17:20               ` Ross Zwisler
2018-07-30 15:43                 ` Matthew Wilcox

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