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* [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2]
@ 2021-01-25 21:30 David Howells
  2021-01-25 21:31 ` [PATCH 01/32] iov_iter: Add ITER_XARRAY David Howells
                   ` (31 more replies)
  0 siblings, 32 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:30 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: linux-afs, Dave Wysochanski, Matthew Wilcox,
	Matthew Wilcox (Oracle),
	dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel


Here's a set of patches to do two things:

 (1) Add a helper library to handle the new VM readahead interface.  This
     is intended to be used unconditionally by the filesystem (whether or
     not caching is enabled) and provides a common framework for doing
     caching, transparent huge pages and, in the future, possibly fscrypt
     and read bandwidth maximisation.  It also allows the netfs and the
     cache to align, expand and slice up a read request from the VM in
     various ways; the netfs need only provide a function to read a stretch
     of data to the pagecache and the helper takes care of the rest.

 (2) Add an alternative fscache/cachfiles I/O API that uses the kiocb
     facility to do async DIO to transfer data to/from the netfs's pages,
     rather than using readpage with wait queue snooping on one side and
     vfs_write() on the other.  It also uses less memory, since it doesn't
     do buffered I/O on the backing file.

     Note that this uses SEEK_HOLE/SEEK_DATA to locate the data available
     to be read from the cache.  Whilst this is an improvement from the
     bmap interface, it still has a problem with regard to a modern
     extent-based filesystem inserting or removing bridging blocks of
     zeros.  Fixing that requires a much greater overhaul.

This is a step towards overhauling the fscache API.  The change is opt-in
on the part of the network filesystem.  A netfs should not try to mix the
old and the new API because of conflicting ways of handling pages and the
PG_fscache page flag and because it would be mixing DIO with buffered I/O.
Further, the helper library can't be used with the old API.

This does not change any of the fscache cookie handling APIs or the way
invalidation is done.

In the near term, I intend to deprecate and remove the old I/O API
(fscache_allocate_page{,s}(), fscache_read_or_alloc_page{,s}(),
fscache_write_page() and fscache_uncache_page()) and eventually replace
most of fscache/cachefiles with something simpler and easier to follow.

The patchset contains five parts:

 (1) Some helper patches, including provision of an ITER_XARRAY iov
     iterator and a function to do readahead expansion.

 (2) Patches to add the netfs helper library.

 (3) A patch to add the fscache/cachefiles kiocb API

 (4) Patches to add support in AFS for this.

 (5) Patches from David Wysochanski to add support in NFS for this.

Jeff Layton also has patches for Ceph for this, though they're not included
on this branch.

With this, AFS without a cache passes all expected xfstests; with a cache,
there's an extra failure, but that's also there before these patches.
Fixing that probably requires a greater overhaul.  Ceph and NFS also pass
the expected tests.

These patches can be found also on:

	https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=fscache-netfs-lib


Changes
=======

 (v2) Fix some bugs and add NFS support.

David
---
Dave Wysochanski (8):
      NFS: Clean up nfs_readpage() and nfs_readpages()
      NFS: In nfs_readpage() only increment NFSIOS_READPAGES when read succeeds
      NFS: Refactor nfs_readpage() and nfs_readpage_async() to use nfs_readdesc
      NFS: Call readpage_async_filler() from nfs_readpage_async()
      NFS: Add nfs_pageio_complete_read() and remove nfs_readpage_async()
      NFS: Allow internal use of read structs and functions
      NFS: Convert to the netfs API and nfs_readpage to use netfs_readpage
      NFS: Convert readpage to readahead and use netfs_readahead for fscache

David Howells (24):
      iov_iter: Add ITER_XARRAY
      vm: Add wait/unlock functions for PG_fscache
      mm: Implement readahead_control pageset expansion
      vfs: Export rw_verify_area() for use by cachefiles
      netfs: Make a netfs helper module
      netfs: Provide readahead and readpage netfs helpers
      netfs: Add tracepoints
      netfs: Gather stats
      netfs: Add write_begin helper
      netfs: Define an interface to talk to a cache
      fscache, cachefiles: Add alternate API to use kiocb for read/write to cache
      afs: Disable use of the fscache I/O routines
      afs: Pass page into dirty region helpers to provide THP size
      afs: Print the operation debug_id when logging an unexpected data version
      afs: Move key to afs_read struct
      afs: Don't truncate iter during data fetch
      afs: Log remote unmarshalling errors
      afs: Set up the iov_iter before calling afs_extract_data()
      afs: Use ITER_XARRAY for writing
      afs: Wait on PG_fscache before modifying/releasing a page
      afs: Extract writeback extension into its own function
      afs: Prepare for use of THPs
      afs: Use the fs operation ops to handle FetchData completion
      afs: Use new fscache read helper API


 fs/Kconfig                    |    1 +
 fs/Makefile                   |    1 +
 fs/afs/Kconfig                |    1 +
 fs/afs/dir.c                  |  225 ++++---
 fs/afs/file.c                 |  472 ++++----------
 fs/afs/fs_operation.c         |    4 +-
 fs/afs/fsclient.c             |  108 +--
 fs/afs/inode.c                |    7 +-
 fs/afs/internal.h             |   57 +-
 fs/afs/rxrpc.c                |  150 ++---
 fs/afs/write.c                |  610 +++++++++--------
 fs/afs/yfsclient.c            |   82 +--
 fs/cachefiles/Makefile        |    1 +
 fs/cachefiles/interface.c     |    5 +-
 fs/cachefiles/internal.h      |    9 +
 fs/cachefiles/rdwr2.c         |  412 ++++++++++++
 fs/fscache/Kconfig            |    1 +
 fs/fscache/Makefile           |    3 +-
 fs/fscache/internal.h         |    3 +
 fs/fscache/page.c             |    2 +-
 fs/fscache/page2.c            |  116 ++++
 fs/fscache/stats.c            |    1 +
 fs/internal.h                 |    5 -
 fs/netfs/Kconfig              |   23 +
 fs/netfs/Makefile             |    5 +
 fs/netfs/internal.h           |   97 +++
 fs/netfs/read_helper.c        | 1155 +++++++++++++++++++++++++++++++++
 fs/netfs/stats.c              |   59 ++
 fs/nfs/file.c                 |    2 +-
 fs/nfs/fscache.c              |  206 +++---
 fs/nfs/fscache.h              |   66 +-
 fs/nfs/internal.h             |    8 +
 fs/nfs/pagelist.c             |    2 +
 fs/nfs/read.c                 |  244 ++++---
 fs/read_write.c               |    1 +
 include/linux/fs.h            |    1 +
 include/linux/fscache-cache.h |    4 +
 include/linux/fscache.h       |   28 +-
 include/linux/netfs.h         |  167 +++++
 include/linux/nfs_fs.h        |    5 +-
 include/linux/nfs_iostat.h    |    2 +-
 include/linux/nfs_page.h      |    1 +
 include/linux/nfs_xdr.h       |    1 +
 include/linux/pagemap.h       |   16 +
 include/net/af_rxrpc.h        |    2 +-
 include/trace/events/afs.h    |   74 +--
 include/trace/events/netfs.h  |  201 ++++++
 mm/filemap.c                  |   18 +
 mm/readahead.c                |   70 ++
 net/rxrpc/recvmsg.c           |    9 +-
 50 files changed, 3457 insertions(+), 1286 deletions(-)
 create mode 100644 fs/cachefiles/rdwr2.c
 create mode 100644 fs/fscache/page2.c
 create mode 100644 fs/netfs/Kconfig
 create mode 100644 fs/netfs/Makefile
 create mode 100644 fs/netfs/internal.h
 create mode 100644 fs/netfs/read_helper.c
 create mode 100644 fs/netfs/stats.c
 create mode 100644 include/linux/netfs.h
 create mode 100644 include/trace/events/netfs.h



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 01/32] iov_iter: Add ITER_XARRAY
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
@ 2021-01-25 21:31 ` David Howells
  2021-01-25 21:31 ` [PATCH 02/32] vm: Add wait/unlock functions for PG_fscache David Howells
                   ` (30 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:31 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: Matthew Wilcox, dhowells, Jeff Layton, David Wysochanski,
	Matthew Wilcox, Alexander Viro, linux-cachefs, linux-afs,
	linux-nfs, linux-cifs, ceph-devel, v9fs-developer, linux-fsdevel,
	linux-kernel

Add an iterator, ITER_XARRAY, that walks through a set of pages attached to
an xarray, starting at a given page and offset and walking for the
specified amount of bytes.  The iterator supports transparent huge pages.

The caller must guarantee that the pages are all present and they must be
locked using PG_locked, PG_writeback or PG_fscache to prevent them from
going away or being migrated whilst they're being accessed.

This is useful for copying data from socket buffers to inodes in network
filesystems and for transferring data between those inodes and the cache
using direct I/O.

Whilst it is true that ITER_BVEC could be used instead, that would require
a bio_vec array to be allocated to refer to all the pages - which should be
redundant if inode->i_pages also points to all these pages.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Matthew Wilcox <willy@infradead.org>
---

 include/linux/uio.h |   11 ++
 lib/iov_iter.c      |  313 +++++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 301 insertions(+), 23 deletions(-)

diff --git a/include/linux/uio.h b/include/linux/uio.h
index 72d88566694e..08b186df54ac 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -10,6 +10,7 @@
 #include <uapi/linux/uio.h>
 
 struct page;
+struct address_space;
 struct pipe_inode_info;
 
 struct kvec {
@@ -24,6 +25,7 @@ enum iter_type {
 	ITER_BVEC = 16,
 	ITER_PIPE = 32,
 	ITER_DISCARD = 64,
+	ITER_XARRAY = 128,
 };
 
 struct iov_iter {
@@ -39,6 +41,7 @@ struct iov_iter {
 		const struct iovec *iov;
 		const struct kvec *kvec;
 		const struct bio_vec *bvec;
+		struct xarray *xarray;
 		struct pipe_inode_info *pipe;
 	};
 	union {
@@ -47,6 +50,7 @@ struct iov_iter {
 			unsigned int head;
 			unsigned int start_head;
 		};
+		loff_t xarray_start;
 	};
 };
 
@@ -80,6 +84,11 @@ static inline bool iov_iter_is_discard(const struct iov_iter *i)
 	return iov_iter_type(i) == ITER_DISCARD;
 }
 
+static inline bool iov_iter_is_xarray(const struct iov_iter *i)
+{
+	return iov_iter_type(i) == ITER_XARRAY;
+}
+
 static inline unsigned char iov_iter_rw(const struct iov_iter *i)
 {
 	return i->type & (READ | WRITE);
@@ -221,6 +230,8 @@ void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_
 void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
 			size_t count);
 void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
+void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
+		     loff_t start, size_t count);
 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
 			size_t maxsize, unsigned maxpages, size_t *start);
 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index a21e6a5792c5..f53a57588489 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -78,7 +78,44 @@
 	}						\
 }
 
-#define iterate_all_kinds(i, n, v, I, B, K) {			\
+#define iterate_xarray(i, n, __v, skip, STEP) {		\
+	struct page *head = NULL;				\
+	size_t wanted = n, seg, offset;				\
+	loff_t start = i->xarray_start + skip;			\
+	pgoff_t index = start >> PAGE_SHIFT;			\
+	int j;							\
+								\
+	XA_STATE(xas, i->xarray, index);			\
+								\
+	rcu_read_lock();						\
+	xas_for_each(&xas, head, ULONG_MAX) {				\
+		if (xas_retry(&xas, head))				\
+			continue;					\
+		if (WARN_ON(xa_is_value(head)))				\
+			break;						\
+		if (WARN_ON(PageHuge(head)))				\
+			break;						\
+		for (j = (head->index < index) ? index - head->index : 0; \
+		     j < thp_nr_pages(head); j++) {			\
+			__v.bv_page = head + j;				\
+			offset = (i->xarray_start + skip) & ~PAGE_MASK;	\
+			seg = PAGE_SIZE - offset;			\
+			__v.bv_offset = offset;				\
+			__v.bv_len = min(n, seg);			\
+			(void)(STEP);					\
+			n -= __v.bv_len;				\
+			skip += __v.bv_len;				\
+			if (n == 0)					\
+				break;					\
+		}							\
+		if (n == 0)						\
+			break;						\
+	}							\
+	rcu_read_unlock();					\
+	n = wanted - n;						\
+}
+
+#define iterate_all_kinds(i, n, v, I, B, K, X) {		\
 	if (likely(n)) {					\
 		size_t skip = i->iov_offset;			\
 		if (unlikely(i->type & ITER_BVEC)) {		\
@@ -90,6 +127,9 @@
 			struct kvec v;				\
 			iterate_kvec(i, n, v, kvec, skip, (K))	\
 		} else if (unlikely(i->type & ITER_DISCARD)) {	\
+		} else if (unlikely(i->type & ITER_XARRAY)) {	\
+			struct bio_vec v;			\
+			iterate_xarray(i, n, v, skip, (X));	\
 		} else {					\
 			const struct iovec *iov;		\
 			struct iovec v;				\
@@ -98,7 +138,7 @@
 	}							\
 }
 
-#define iterate_and_advance(i, n, v, I, B, K) {			\
+#define iterate_and_advance(i, n, v, I, B, K, X) {		\
 	if (unlikely(i->count < n))				\
 		n = i->count;					\
 	if (i->count) {						\
@@ -123,6 +163,9 @@
 			i->kvec = kvec;				\
 		} else if (unlikely(i->type & ITER_DISCARD)) {	\
 			skip += n;				\
+		} else if (unlikely(i->type & ITER_XARRAY)) {	\
+			struct bio_vec v;			\
+			iterate_xarray(i, n, v, skip, (X))	\
 		} else {					\
 			const struct iovec *iov;		\
 			struct iovec v;				\
@@ -636,7 +679,9 @@ size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
 		copyout(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len),
 		memcpy_to_page(v.bv_page, v.bv_offset,
 			       (from += v.bv_len) - v.bv_len, v.bv_len),
-		memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len)
+		memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len),
+		memcpy_to_page(v.bv_page, v.bv_offset,
+			       (from += v.bv_len) - v.bv_len, v.bv_len)
 	)
 
 	return bytes;
@@ -752,6 +797,16 @@ size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
 			bytes = curr_addr - s_addr - rem;
 			return bytes;
 		}
+		}),
+		({
+		rem = copy_mc_to_page(v.bv_page, v.bv_offset,
+				      (from += v.bv_len) - v.bv_len, v.bv_len);
+		if (rem) {
+			curr_addr = (unsigned long) from;
+			bytes = curr_addr - s_addr - rem;
+			rcu_read_unlock();
+			return bytes;
+		}
 		})
 	)
 
@@ -773,7 +828,9 @@ size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
 		copyin((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
 		memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
 				 v.bv_offset, v.bv_len),
-		memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
+		memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
+		memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
+				 v.bv_offset, v.bv_len)
 	)
 
 	return bytes;
@@ -799,7 +856,9 @@ bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
 		0;}),
 		memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
 				 v.bv_offset, v.bv_len),
-		memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
+		memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
+		memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
+				 v.bv_offset, v.bv_len)
 	)
 
 	iov_iter_advance(i, bytes);
@@ -819,7 +878,9 @@ size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
 					 v.iov_base, v.iov_len),
 		memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
 				 v.bv_offset, v.bv_len),
-		memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
+		memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
+		memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
+				 v.bv_offset, v.bv_len)
 	)
 
 	return bytes;
@@ -854,7 +915,9 @@ size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
 		memcpy_page_flushcache((to += v.bv_len) - v.bv_len, v.bv_page,
 				 v.bv_offset, v.bv_len),
 		memcpy_flushcache((to += v.iov_len) - v.iov_len, v.iov_base,
-			v.iov_len)
+			v.iov_len),
+		memcpy_page_flushcache((to += v.bv_len) - v.bv_len, v.bv_page,
+				 v.bv_offset, v.bv_len)
 	)
 
 	return bytes;
@@ -878,7 +941,9 @@ bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
 		0;}),
 		memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
 				 v.bv_offset, v.bv_len),
-		memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
+		memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
+		memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
+				 v.bv_offset, v.bv_len)
 	)
 
 	iov_iter_advance(i, bytes);
@@ -915,7 +980,7 @@ size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
 {
 	if (unlikely(!page_copy_sane(page, offset, bytes)))
 		return 0;
-	if (i->type & (ITER_BVEC|ITER_KVEC)) {
+	if (i->type & (ITER_BVEC | ITER_KVEC | ITER_XARRAY)) {
 		void *kaddr = kmap_atomic(page);
 		size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
 		kunmap_atomic(kaddr);
@@ -938,7 +1003,7 @@ size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
 		WARN_ON(1);
 		return 0;
 	}
-	if (i->type & (ITER_BVEC|ITER_KVEC)) {
+	if (i->type & (ITER_BVEC | ITER_KVEC | ITER_XARRAY)) {
 		void *kaddr = kmap_atomic(page);
 		size_t wanted = _copy_from_iter(kaddr + offset, bytes, i);
 		kunmap_atomic(kaddr);
@@ -982,7 +1047,8 @@ size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
 	iterate_and_advance(i, bytes, v,
 		clear_user(v.iov_base, v.iov_len),
 		memzero_page(v.bv_page, v.bv_offset, v.bv_len),
-		memset(v.iov_base, 0, v.iov_len)
+		memset(v.iov_base, 0, v.iov_len),
+		memzero_page(v.bv_page, v.bv_offset, v.bv_len)
 	)
 
 	return bytes;
@@ -1006,7 +1072,9 @@ size_t iov_iter_copy_from_user_atomic(struct page *page,
 		copyin((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
 		memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page,
 				 v.bv_offset, v.bv_len),
-		memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
+		memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
+		memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page,
+				 v.bv_offset, v.bv_len)
 	)
 	kunmap_atomic(kaddr);
 	return bytes;
@@ -1077,7 +1145,12 @@ void iov_iter_advance(struct iov_iter *i, size_t size)
 		i->count -= size;
 		return;
 	}
-	iterate_and_advance(i, size, v, 0, 0, 0)
+	if (unlikely(iov_iter_is_xarray(i))) {
+		i->iov_offset += size;
+		i->count -= size;
+		return;
+	}
+	iterate_and_advance(i, size, v, 0, 0, 0, 0)
 }
 EXPORT_SYMBOL(iov_iter_advance);
 
@@ -1121,7 +1194,12 @@ void iov_iter_revert(struct iov_iter *i, size_t unroll)
 		return;
 	}
 	unroll -= i->iov_offset;
-	if (iov_iter_is_bvec(i)) {
+	if (iov_iter_is_xarray(i)) {
+		BUG(); /* We should never go beyond the start of the specified
+			* range since we might then be straying into pages that
+			* aren't pinned.
+			*/
+	} else if (iov_iter_is_bvec(i)) {
 		const struct bio_vec *bvec = i->bvec;
 		while (1) {
 			size_t n = (--bvec)->bv_len;
@@ -1158,9 +1236,9 @@ size_t iov_iter_single_seg_count(const struct iov_iter *i)
 		return i->count;	// it is a silly place, anyway
 	if (i->nr_segs == 1)
 		return i->count;
-	if (unlikely(iov_iter_is_discard(i)))
+	if (unlikely(iov_iter_is_discard(i) || iov_iter_is_xarray(i)))
 		return i->count;
-	else if (iov_iter_is_bvec(i))
+	if (iov_iter_is_bvec(i))
 		return min(i->count, i->bvec->bv_len - i->iov_offset);
 	else
 		return min(i->count, i->iov->iov_len - i->iov_offset);
@@ -1208,6 +1286,31 @@ void iov_iter_pipe(struct iov_iter *i, unsigned int direction,
 }
 EXPORT_SYMBOL(iov_iter_pipe);
 
+/**
+ * iov_iter_xarray - Initialise an I/O iterator to use the pages in an xarray
+ * @i: The iterator to initialise.
+ * @direction: The direction of the transfer.
+ * @xarray: The xarray to access.
+ * @start: The start file position.
+ * @count: The size of the I/O buffer in bytes.
+ *
+ * Set up an I/O iterator to either draw data out of the pages attached to an
+ * inode or to inject data into those pages.  The pages *must* be prevented
+ * from evaporation, either by taking a ref on them or locking them by the
+ * caller.
+ */
+void iov_iter_xarray(struct iov_iter *i, unsigned int direction,
+		     struct xarray *xarray, loff_t start, size_t count)
+{
+	BUG_ON(direction & ~1);
+	i->type = ITER_XARRAY | (direction & (READ | WRITE));
+	i->xarray = xarray;
+	i->xarray_start = start;
+	i->count = count;
+	i->iov_offset = 0;
+}
+EXPORT_SYMBOL(iov_iter_xarray);
+
 /**
  * iov_iter_discard - Initialise an I/O iterator that discards data
  * @i: The iterator to initialise.
@@ -1241,7 +1344,8 @@ unsigned long iov_iter_alignment(const struct iov_iter *i)
 	iterate_all_kinds(i, size, v,
 		(res |= (unsigned long)v.iov_base | v.iov_len, 0),
 		res |= v.bv_offset | v.bv_len,
-		res |= (unsigned long)v.iov_base | v.iov_len
+		res |= (unsigned long)v.iov_base | v.iov_len,
+		res |= v.bv_offset | v.bv_len
 	)
 	return res;
 }
@@ -1263,7 +1367,9 @@ unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
 		(res |= (!res ? 0 : (unsigned long)v.bv_offset) |
 			(size != v.bv_len ? size : 0)),
 		(res |= (!res ? 0 : (unsigned long)v.iov_base) |
-			(size != v.iov_len ? size : 0))
+			(size != v.iov_len ? size : 0)),
+		(res |= (!res ? 0 : (unsigned long)v.bv_offset) |
+			(size != v.bv_len ? size : 0))
 		);
 	return res;
 }
@@ -1313,6 +1419,75 @@ static ssize_t pipe_get_pages(struct iov_iter *i,
 	return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start);
 }
 
+static ssize_t iter_xarray_copy_pages(struct page **pages, struct xarray *xa,
+				       pgoff_t index, unsigned int nr_pages)
+{
+	XA_STATE(xas, xa, index);
+	struct page *page;
+	unsigned int ret = 0;
+
+	rcu_read_lock();
+	for (page = xas_load(&xas); page; page = xas_next(&xas)) {
+		if (xas_retry(&xas, page))
+			continue;
+
+		/* Has the page moved or been split? */
+		if (unlikely(page != xas_reload(&xas))) {
+			xas_reset(&xas);
+			continue;
+		}
+
+		pages[ret] = find_subpage(page, xas.xa_index);
+		get_page(pages[ret]);
+		if (++ret == nr_pages)
+			break;
+	}
+	rcu_read_unlock();
+	return ret;
+}
+
+static ssize_t iter_xarray_get_pages(struct iov_iter *i,
+				     struct page **pages, size_t maxsize,
+				     unsigned maxpages, size_t *_start_offset)
+{
+	unsigned nr, offset;
+	pgoff_t index, count;
+	size_t size = maxsize, actual;
+	loff_t pos;
+
+	if (!size || !maxpages)
+		return 0;
+
+	pos = i->xarray_start + i->iov_offset;
+	index = pos >> PAGE_SHIFT;
+	offset = pos & ~PAGE_MASK;
+	*_start_offset = offset;
+
+	count = 1;
+	if (size > PAGE_SIZE - offset) {
+		size -= PAGE_SIZE - offset;
+		count += size >> PAGE_SHIFT;
+		size &= ~PAGE_MASK;
+		if (size)
+			count++;
+	}
+
+	if (count > maxpages)
+		count = maxpages;
+
+	nr = iter_xarray_copy_pages(pages, i->xarray, index, count);
+	if (nr == 0)
+		return 0;
+
+	actual = PAGE_SIZE * nr;
+	actual -= offset;
+	if (nr == count && size > 0) {
+		unsigned last_offset = (nr > 1) ? 0 : offset;
+		actual -= PAGE_SIZE - (last_offset + size);
+	}
+	return actual;
+}
+
 ssize_t iov_iter_get_pages(struct iov_iter *i,
 		   struct page **pages, size_t maxsize, unsigned maxpages,
 		   size_t *start)
@@ -1322,6 +1497,8 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
 
 	if (unlikely(iov_iter_is_pipe(i)))
 		return pipe_get_pages(i, pages, maxsize, maxpages, start);
+	if (unlikely(iov_iter_is_xarray(i)))
+		return iter_xarray_get_pages(i, pages, maxsize, maxpages, start);
 	if (unlikely(iov_iter_is_discard(i)))
 		return -EFAULT;
 
@@ -1348,7 +1525,8 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
 		return v.bv_len;
 	}),({
 		return -EFAULT;
-	})
+	}),
+	0
 	)
 	return 0;
 }
@@ -1392,6 +1570,51 @@ static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
 	return n;
 }
 
+static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i,
+					   struct page ***pages, size_t maxsize,
+					   size_t *_start_offset)
+{
+	struct page **p;
+	unsigned nr, offset;
+	pgoff_t index, count;
+	size_t size = maxsize, actual;
+	loff_t pos;
+
+	if (!size)
+		return 0;
+
+	pos = i->xarray_start + i->iov_offset;
+	index = pos >> PAGE_SHIFT;
+	offset = pos & ~PAGE_MASK;
+	*_start_offset = offset;
+
+	count = 1;
+	if (size > PAGE_SIZE - offset) {
+		size -= PAGE_SIZE - offset;
+		count += size >> PAGE_SHIFT;
+		size &= ~PAGE_MASK;
+		if (size)
+			count++;
+	}
+
+	p = get_pages_array(count);
+	if (!p)
+		return -ENOMEM;
+	*pages = p;
+
+	nr = iter_xarray_copy_pages(p, i->xarray, index, count);
+	if (nr == 0)
+		return 0;
+
+	actual = PAGE_SIZE * nr;
+	actual -= offset;
+	if (nr == count && size > 0) {
+		unsigned last_offset = (nr > 1) ? 0 : offset;
+		actual -= PAGE_SIZE - (last_offset + size);
+	}
+	return actual;
+}
+
 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
 		   struct page ***pages, size_t maxsize,
 		   size_t *start)
@@ -1403,6 +1626,8 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
 
 	if (unlikely(iov_iter_is_pipe(i)))
 		return pipe_get_pages_alloc(i, pages, maxsize, start);
+	if (unlikely(iov_iter_is_xarray(i)))
+		return iter_xarray_get_pages_alloc(i, pages, maxsize, start);
 	if (unlikely(iov_iter_is_discard(i)))
 		return -EFAULT;
 
@@ -1435,7 +1660,7 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
 		return v.bv_len;
 	}),({
 		return -EFAULT;
-	})
+	}), 0
 	)
 	return 0;
 }
@@ -1473,6 +1698,13 @@ size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
 				      v.iov_base, v.iov_len,
 				      sum, off);
 		off += v.iov_len;
+	}), ({
+		char *p = kmap_atomic(v.bv_page);
+		sum = csum_and_memcpy((to += v.bv_len) - v.bv_len,
+				      p + v.bv_offset, v.bv_len,
+				      sum, off);
+		kunmap_atomic(p);
+		off += v.bv_len;
 	})
 	)
 	*csum = sum;
@@ -1514,6 +1746,13 @@ bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum,
 				      v.iov_base, v.iov_len,
 				      sum, off);
 		off += v.iov_len;
+	}), ({
+		char *p = kmap_atomic(v.bv_page);
+		sum = csum_and_memcpy((to += v.bv_len) - v.bv_len,
+				      p + v.bv_offset, v.bv_len,
+				      sum, off);
+		kunmap_atomic(p);
+		off += v.bv_len;
 	})
 	)
 	*csum = sum;
@@ -1559,6 +1798,13 @@ size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csump,
 				     (from += v.iov_len) - v.iov_len,
 				     v.iov_len, sum, off);
 		off += v.iov_len;
+	}), ({
+		char *p = kmap_atomic(v.bv_page);
+		sum = csum_and_memcpy(p + v.bv_offset,
+				      (from += v.bv_len) - v.bv_len,
+				      v.bv_len, sum, off);
+		kunmap_atomic(p);
+		off += v.bv_len;
 	})
 	)
 	*csum = sum;
@@ -1608,6 +1854,21 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages)
 		npages = pipe_space_for_user(iter_head, pipe->tail, pipe);
 		if (npages >= maxpages)
 			return maxpages;
+	} else if (unlikely(iov_iter_is_xarray(i))) {
+		unsigned offset;
+
+		offset = (i->xarray_start + i->iov_offset) & ~PAGE_MASK;
+
+		npages = 1;
+		if (size > PAGE_SIZE - offset) {
+			size -= PAGE_SIZE - offset;
+			npages += size >> PAGE_SHIFT;
+			size &= ~PAGE_MASK;
+			if (size)
+				npages++;
+		}
+		if (npages >= maxpages)
+			return maxpages;
 	} else iterate_all_kinds(i, size, v, ({
 		unsigned long p = (unsigned long)v.iov_base;
 		npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
@@ -1624,7 +1885,8 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages)
 			- p / PAGE_SIZE;
 		if (npages >= maxpages)
 			return maxpages;
-	})
+	}),
+	0
 	)
 	return npages;
 }
@@ -1637,7 +1899,7 @@ const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
 		WARN_ON(1);
 		return NULL;
 	}
-	if (unlikely(iov_iter_is_discard(new)))
+	if (unlikely(iov_iter_is_discard(new) || iov_iter_is_xarray(new)))
 		return NULL;
 	if (iov_iter_is_bvec(new))
 		return new->bvec = kmemdup(new->bvec,
@@ -1842,7 +2104,12 @@ int iov_iter_for_each_range(struct iov_iter *i, size_t bytes,
 		kunmap(v.bv_page);
 		err;}), ({
 		w = v;
-		err = f(&w, context);})
+		err = f(&w, context);}), ({
+		w.iov_base = kmap(v.bv_page) + v.bv_offset;
+		w.iov_len = v.bv_len;
+		err = f(&w, context);
+		kunmap(v.bv_page);
+		err;})
 	)
 	return err;
 }



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 02/32] vm: Add wait/unlock functions for PG_fscache
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
  2021-01-25 21:31 ` [PATCH 01/32] iov_iter: Add ITER_XARRAY David Howells
@ 2021-01-25 21:31 ` David Howells
  2021-01-25 21:31 ` [PATCH 03/32] mm: Implement readahead_control pageset expansion David Howells
                   ` (29 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:31 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Add functions to unlock and wait for unlock of PG_fscache analogously with
those for PG_lock.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 include/linux/pagemap.h |   14 ++++++++++++++
 mm/filemap.c            |   18 ++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index d5570deff400..1fa160e682fa 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -591,6 +591,7 @@ extern int __lock_page_async(struct page *page, struct wait_page_queue *wait);
 extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
 				unsigned int flags);
 extern void unlock_page(struct page *page);
+extern void unlock_page_fscache(struct page *page);
 
 /*
  * Return true if the page was successfully locked
@@ -681,6 +682,19 @@ static inline int wait_on_page_locked_killable(struct page *page)
 	return wait_on_page_bit_killable(compound_head(page), PG_locked);
 }
 
+/**
+ * wait_on_page_fscache - Wait for PG_fscache to be cleared on a page
+ * @page: The page
+ *
+ * Wait for the fscache mark to be removed from a page, usually signifying the
+ * completion of a write from that page to the cache.
+ */
+static inline void wait_on_page_fscache(struct page *page)
+{
+	if (PagePrivate2(page))
+		wait_on_page_bit(compound_head(page), PG_fscache);
+}
+
 extern void put_and_wait_on_page_locked(struct page *page);
 
 void wait_on_page_writeback(struct page *page);
diff --git a/mm/filemap.c b/mm/filemap.c
index 5c9d564317a5..91fcae006d64 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1466,6 +1466,24 @@ void unlock_page(struct page *page)
 }
 EXPORT_SYMBOL(unlock_page);
 
+/**
+ * unlock_page_fscache - Unlock a page pinned with PG_fscache
+ * @page: The page
+ *
+ * Unlocks the page and wakes up sleepers in wait_on_page_fscache().  Also
+ * wakes those waiting for the lock and writeback bits because the wakeup
+ * mechanism is shared.  But that's OK - those sleepers will just go back to
+ * sleep.
+ */
+void unlock_page_fscache(struct page *page)
+{
+	page = compound_head(page);
+	VM_BUG_ON_PAGE(!PagePrivate2(page), page);
+	clear_bit_unlock(PG_fscache, &page->flags);
+	wake_up_page_bit(page, PG_fscache);
+}
+EXPORT_SYMBOL(unlock_page_fscache);
+
 /**
  * end_page_writeback - end writeback against a page
  * @page: the page



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 03/32] mm: Implement readahead_control pageset expansion
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
  2021-01-25 21:31 ` [PATCH 01/32] iov_iter: Add ITER_XARRAY David Howells
  2021-01-25 21:31 ` [PATCH 02/32] vm: Add wait/unlock functions for PG_fscache David Howells
@ 2021-01-25 21:31 ` David Howells
  2021-01-25 21:31 ` [PATCH 04/32] vfs: Export rw_verify_area() for use by cachefiles David Howells
                   ` (28 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:31 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: Matthew Wilcox (Oracle),
	dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Provide a function, readahead_expand(), that expands the set of pages
specified by a readahead_control object to encompass a revised area with a
proposed size and length.

The proposed area must include all of the old area and may be expanded yet
more by this function so that the edges align on (transparent huge) page
boundaries as allocated.

The expansion will be cut short if a page already exists in either of the
areas being expanded into.  Note that any expansion made in such a case is
not rolled back.

This will be used by fscache so that reads can be expanded to cache granule
boundaries, thereby allowing whole granules to be stored in the cache, but
there are other potential users also.

Suggested-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: David Howells <dhowells@redhat.com>
---

 include/linux/pagemap.h |    2 +
 mm/readahead.c          |   70 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 1fa160e682fa..4935ad6171c1 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -774,6 +774,8 @@ extern void __delete_from_page_cache(struct page *page, void *shadow);
 int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);
 void delete_from_page_cache_batch(struct address_space *mapping,
 				  struct pagevec *pvec);
+void readahead_expand(struct readahead_control *ractl,
+		      loff_t new_start, size_t new_len);
 
 /*
  * Like add_to_page_cache_locked, but used to add newly allocated pages:
diff --git a/mm/readahead.c b/mm/readahead.c
index c5b0457415be..4446dada0bc2 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -638,3 +638,73 @@ SYSCALL_DEFINE3(readahead, int, fd, loff_t, offset, size_t, count)
 {
 	return ksys_readahead(fd, offset, count);
 }
+
+/**
+ * readahead_expand - Expand a readahead request
+ * @ractl: The request to be expanded
+ * @new_start: The revised start
+ * @new_len: The revised size of the request
+ *
+ * Attempt to expand a readahead request outwards from the current size to the
+ * specified size by inserting locked pages before and after the current window
+ * to increase the size to the new window.  This may involve the insertion of
+ * THPs, in which case the window may get expanded even beyond what was
+ * requested.
+ *
+ * The algorithm will stop if it encounters a conflicting page already in the
+ * pagecache and leave a smaller expansion than requested.
+ *
+ * The caller must check for this by examining the revised @ractl object for a
+ * different expansion than was requested.
+ */
+void readahead_expand(struct readahead_control *ractl,
+		      loff_t new_start, size_t new_len)
+{
+	struct address_space *mapping = ractl->mapping;
+	pgoff_t new_index, new_nr_pages;
+	gfp_t gfp_mask = readahead_gfp_mask(mapping);
+
+	new_index = new_start / PAGE_SIZE;
+
+	/* Expand the leading edge downwards */
+	while (ractl->_index > new_index) {
+		unsigned long index = ractl->_index - 1;
+		struct page *page = xa_load(&mapping->i_pages, index);
+
+		if (page && !xa_is_value(page))
+			return; /* Page apparently present */
+
+		page = __page_cache_alloc(gfp_mask);
+		if (!page)
+			return;
+		if (add_to_page_cache_lru(page, mapping, index, gfp_mask) < 0) {
+			put_page(page);
+			return;
+		}
+
+		ractl->_nr_pages++;
+		ractl->_index = page->index;
+	}
+
+	new_len += new_start - readahead_pos(ractl);
+	new_nr_pages = DIV_ROUND_UP(new_len, PAGE_SIZE);
+
+	/* Expand the trailing edge upwards */
+	while (ractl->_nr_pages < new_nr_pages) {
+		unsigned long index = ractl->_index + ractl->_nr_pages;
+		struct page *page = xa_load(&mapping->i_pages, index);
+
+		if (page && !xa_is_value(page))
+			return; /* Page apparently present */
+
+		page = __page_cache_alloc(gfp_mask);
+		if (!page)
+			return;
+		if (add_to_page_cache_lru(page, mapping, index, gfp_mask) < 0) {
+			put_page(page);
+			return;
+		}
+		ractl->_nr_pages++;
+	}
+}
+EXPORT_SYMBOL(readahead_expand);



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 04/32] vfs: Export rw_verify_area() for use by cachefiles
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (2 preceding siblings ...)
  2021-01-25 21:31 ` [PATCH 03/32] mm: Implement readahead_control pageset expansion David Howells
@ 2021-01-25 21:31 ` David Howells
  2021-01-25 21:31 ` [PATCH 05/32] netfs: Make a netfs helper module David Howells
                   ` (27 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:31 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Export rw_verify_area() for so that cachefiles can use it before issuing
call_read_iter() and call_write_iter() to effect async DIO operations
against the cache.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/internal.h      |    5 -----
 fs/read_write.c    |    1 +
 include/linux/fs.h |    1 +
 3 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/fs/internal.h b/fs/internal.h
index 77c50befbfbe..92e686249c40 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -164,11 +164,6 @@ extern char *simple_dname(struct dentry *, char *, int);
 extern void dput_to_list(struct dentry *, struct list_head *);
 extern void shrink_dentry_list(struct list_head *);
 
-/*
- * read_write.c
- */
-extern int rw_verify_area(int, struct file *, const loff_t *, size_t);
-
 /*
  * pipe.c
  */
diff --git a/fs/read_write.c b/fs/read_write.c
index 75f764b43418..fe84e11245bd 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -400,6 +400,7 @@ int rw_verify_area(int read_write, struct file *file, const loff_t *ppos, size_t
 	return security_file_permission(file,
 				read_write == READ ? MAY_READ : MAY_WRITE);
 }
+EXPORT_SYMBOL(rw_verify_area);
 
 static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
 {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index fd47deea7c17..493804856ab3 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2760,6 +2760,7 @@ extern int notify_change(struct dentry *, struct iattr *, struct inode **);
 extern int inode_permission(struct inode *, int);
 extern int generic_permission(struct inode *, int);
 extern int __check_sticky(struct inode *dir, struct inode *inode);
+extern int rw_verify_area(int, struct file *, const loff_t *, size_t);
 
 static inline bool execute_ok(struct inode *inode)
 {



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 05/32] netfs: Make a netfs helper module
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (3 preceding siblings ...)
  2021-01-25 21:31 ` [PATCH 04/32] vfs: Export rw_verify_area() for use by cachefiles David Howells
@ 2021-01-25 21:31 ` David Howells
  2021-01-25 21:32 ` [PATCH 06/32] netfs: Provide readahead and readpage netfs helpers David Howells
                   ` (26 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:31 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Make a netfs helper module to manage read request segmentation, caching
support and transparent huge page support on behalf of a network
filesystem.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/netfs/Kconfig |    8 ++++++++
 1 file changed, 8 insertions(+)
 create mode 100644 fs/netfs/Kconfig

diff --git a/fs/netfs/Kconfig b/fs/netfs/Kconfig
new file mode 100644
index 000000000000..2ebf90e6ca95
--- /dev/null
+++ b/fs/netfs/Kconfig
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+config NETFS_SUPPORT
+	tristate "Support for network filesystem high-level I/O"
+	help
+	  This option enables support for network filesystems, including
+	  helpers for high-level buffered I/O, abstracting out read
+	  segmentation, local caching and transparent huge page support.



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 06/32] netfs: Provide readahead and readpage netfs helpers
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (4 preceding siblings ...)
  2021-01-25 21:31 ` [PATCH 05/32] netfs: Make a netfs helper module David Howells
@ 2021-01-25 21:32 ` David Howells
  2021-01-25 21:32 ` [PATCH 07/32] netfs: Add tracepoints David Howells
                   ` (25 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:32 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Add a pair of helper functions:

 (*) netfs_readahead()
 (*) netfs_readpage()

to do the work of handling a readahead or a readpage, where the page(s)
that form part of the request may be split between the local cache, the
server or just require clearing, and may be single pages and transparent
huge pages.  This is all handled within the helper.

Note that while both will read from the cache if there is data present,
only netfs_readahead() will expand the request beyond what it was asked to
do, and only netfs_readahead() will write back to the cache.

netfs_readpage(), on the other hand, is synchronous and only fetches the
page (which might be a THP) it is asked for.

The netfs gives the helper parameters from the VM, the cache cookie it
wants to use (or NULL) and a table of operations (only one of which is
mandatory):

 (*) expand_readahead() [optional]

     Called to allow the netfs to request an expansion of a readahead
     request to meet its own alignment requirements.  This is done by
     changing rreq->start and rreq->len.

 (*) clamp_length() [optional]

     Called to allow the netfs to cut down a subrequest to meet its own
     boundary requirements.  If it does this, the helper will generate
     additional subrequests until the full request is satisfied.

 (*) is_still_valid() [optional]

     Called to find out if the data just read from the cache has been
     invalidated and must be reread from the server.

 (*) issue_op() [required]

     Called to ask the netfs to issue a read to the server.  The subrequest
     describes the read.  The read request holds information about the file
     being accessed.

     The netfs can cache information in rreq->netfs_priv.

     Upon completion, the netfs should set the error, transferred and can
     also set FSCACHE_SREQ_CLEAR_TAIL and then call
     fscache_subreq_terminated().

 (*) done() [optional]

     Called after the pages have been unlocked.  The read request is still
     pinning the file and mapping and may still be pinning pages with
     PG_fscache.  rreq->error indicates any error that has been
     accumulated.

 (*) cleanup() [optional]

     Called when the helper is disposing of a finished read request.  This
     allows the netfs to clear rreq->netfs_priv.

Netfs support is enabled with CONFIG_NETFS_SUPPORT=y.  It will be built
even if CONFIG_FSCACHE=n and in this case much of it should be optimised
away, allowing the filesystem to use it even when caching is disabled.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/Kconfig              |    1 
 fs/Makefile             |    1 
 fs/netfs/Makefile       |    6 
 fs/netfs/internal.h     |   61 ++++
 fs/netfs/read_helper.c  |  711 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/fscache.h |   11 -
 include/linux/netfs.h   |  108 +++++++
 7 files changed, 889 insertions(+), 10 deletions(-)
 create mode 100644 fs/netfs/Makefile
 create mode 100644 fs/netfs/internal.h
 create mode 100644 fs/netfs/read_helper.c
 create mode 100644 include/linux/netfs.h

diff --git a/fs/Kconfig b/fs/Kconfig
index aa4c12282301..e3dfbbea502f 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -307,6 +307,7 @@ menuconfig NETWORK_FILESYSTEMS
 
 if NETWORK_FILESYSTEMS
 
+source "fs/netfs/Kconfig"
 source "fs/nfs/Kconfig"
 source "fs/nfsd/Kconfig"
 
diff --git a/fs/Makefile b/fs/Makefile
index 999d1a23f036..e922c3bc0a43 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -68,6 +68,7 @@ obj-$(CONFIG_PROFILING)		+= dcookies.o
 obj-$(CONFIG_DLM)		+= dlm/
  
 # Do not add any filesystems before this line
+obj-$(CONFIG_NETFS_SUPPORT)	+= netfs/
 obj-$(CONFIG_FSCACHE)		+= fscache/
 obj-$(CONFIG_REISERFS_FS)	+= reiserfs/
 obj-$(CONFIG_EXT4_FS)		+= ext4/
diff --git a/fs/netfs/Makefile b/fs/netfs/Makefile
new file mode 100644
index 000000000000..4b4eff2ba369
--- /dev/null
+++ b/fs/netfs/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
+
+netfs-y := \
+	read_helper.o
+
+obj-$(CONFIG_NETFS_SUPPORT) := netfs.o
diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h
new file mode 100644
index 000000000000..ee665c0e7dc8
--- /dev/null
+++ b/fs/netfs/internal.h
@@ -0,0 +1,61 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Internal definitions for network filesystem support
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#ifdef pr_fmt
+#undef pr_fmt
+#endif
+
+#define pr_fmt(fmt) "netfs: " fmt
+
+/*
+ * read_helper.c
+ */
+extern unsigned int netfs_debug;
+
+#define netfs_stat(x) do {} while(0)
+#define netfs_stat_d(x) do {} while(0)
+
+/*****************************************************************************/
+/*
+ * debug tracing
+ */
+#define dbgprintk(FMT, ...) \
+	printk("[%-6.6s] "FMT"\n", current->comm, ##__VA_ARGS__)
+
+#define kenter(FMT, ...) dbgprintk("==> %s("FMT")", __func__, ##__VA_ARGS__)
+#define kleave(FMT, ...) dbgprintk("<== %s()"FMT"", __func__, ##__VA_ARGS__)
+#define kdebug(FMT, ...) dbgprintk(FMT, ##__VA_ARGS__)
+
+#ifdef __KDEBUG
+#define _enter(FMT, ...) kenter(FMT, ##__VA_ARGS__)
+#define _leave(FMT, ...) kleave(FMT, ##__VA_ARGS__)
+#define _debug(FMT, ...) kdebug(FMT, ##__VA_ARGS__)
+
+#elif defined(CONFIG_NETFS_DEBUG)
+#define _enter(FMT, ...)			\
+do {						\
+	if (netfs_debug)			\
+		kenter(FMT, ##__VA_ARGS__);	\
+} while (0)
+
+#define _leave(FMT, ...)			\
+do {						\
+	if (netfs_debug)			\
+		kleave(FMT, ##__VA_ARGS__);	\
+} while (0)
+
+#define _debug(FMT, ...)			\
+do {						\
+	if (netfs_debug)			\
+		kdebug(FMT, ##__VA_ARGS__);	\
+} while (0)
+
+#else
+#define _enter(FMT, ...) no_printk("==> %s("FMT")", __func__, ##__VA_ARGS__)
+#define _leave(FMT, ...) no_printk("<== %s()"FMT"", __func__, ##__VA_ARGS__)
+#define _debug(FMT, ...) no_printk(FMT, ##__VA_ARGS__)
+#endif
diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
new file mode 100644
index 000000000000..e5264e9d8912
--- /dev/null
+++ b/fs/netfs/read_helper.c
@@ -0,0 +1,711 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Network filesystem high-level read support.
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/module.h>
+#include <linux/export.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/uio.h>
+#include <linux/sched/mm.h>
+#include <linux/task_io_accounting_ops.h>
+#include <linux/netfs.h>
+#include "internal.h"
+
+MODULE_DESCRIPTION("Network fs support");
+MODULE_AUTHOR("Red Hat, Inc.");
+MODULE_LICENSE("GPL");
+
+unsigned netfs_debug;
+module_param_named(debug, netfs_debug, uint, S_IWUSR | S_IRUGO);
+MODULE_PARM_DESC(netfs_debug, "Netfs support debugging mask");
+
+static void netfs_rreq_work(struct work_struct *);
+static void __netfs_put_subrequest(struct netfs_read_subrequest *);
+
+static void netfs_put_subrequest(struct netfs_read_subrequest *subreq)
+{
+	if (refcount_dec_and_test(&subreq->usage))
+		__netfs_put_subrequest(subreq);
+}
+
+static struct netfs_read_request *netfs_alloc_read_request(
+	const struct netfs_read_request_ops *ops, void *netfs_priv,
+	struct file *file)
+{
+	struct netfs_read_request *rreq;
+
+	rreq = kzalloc(sizeof(struct netfs_read_request), GFP_KERNEL);
+	if (rreq) {
+		rreq->netfs_ops	= ops;
+		rreq->netfs_priv = netfs_priv;
+		rreq->inode	= file_inode(file);
+		rreq->i_size	= i_size_read(rreq->inode);
+		INIT_LIST_HEAD(&rreq->subrequests);
+		INIT_WORK(&rreq->work, netfs_rreq_work);
+		refcount_set(&rreq->usage, 1);
+		__set_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
+		ops->init_rreq(rreq, file);
+	}
+
+	return rreq;
+}
+
+static void netfs_get_read_request(struct netfs_read_request *rreq)
+{
+	refcount_inc(&rreq->usage);
+}
+
+static void netfs_rreq_clear_subreqs(struct netfs_read_request *rreq)
+{
+	struct netfs_read_subrequest *subreq;
+
+	while (!list_empty(&rreq->subrequests)) {
+		subreq = list_first_entry(&rreq->subrequests,
+					  struct netfs_read_subrequest, rreq_link);
+		list_del(&subreq->rreq_link);
+		netfs_put_subrequest(subreq);
+	}
+}
+
+static void netfs_free_read_request(struct work_struct *work)
+{
+	struct netfs_read_request *rreq =
+		container_of(work, struct netfs_read_request, work);
+	netfs_rreq_clear_subreqs(rreq);
+	if (rreq->netfs_priv)
+		rreq->netfs_ops->cleanup(rreq->mapping, rreq->netfs_priv);
+	kfree(rreq);
+}
+
+static void netfs_put_read_request(struct netfs_read_request *rreq)
+{
+	if (refcount_dec_and_test(&rreq->usage)) {
+		if (in_softirq()) {
+			rreq->work.func = netfs_free_read_request;
+			if (!queue_work(system_unbound_wq, &rreq->work))
+				BUG();
+		} else {
+			netfs_free_read_request(&rreq->work);
+		}
+	}
+}
+
+/*
+ * Allocate and partially initialise an I/O request structure.
+ */
+static struct netfs_read_subrequest *netfs_alloc_subrequest(
+	struct netfs_read_request *rreq)
+{
+	struct netfs_read_subrequest *subreq;
+
+	subreq = kzalloc(sizeof(struct netfs_read_subrequest), GFP_KERNEL);
+	if (subreq) {
+		INIT_LIST_HEAD(&subreq->rreq_link);
+		refcount_set(&subreq->usage, 2);
+		subreq->rreq = rreq;
+	}
+
+	return subreq;
+}
+
+static void netfs_get_read_subrequest(struct netfs_read_subrequest *subreq)
+{
+	refcount_inc(&subreq->usage);
+}
+
+static void __netfs_put_subrequest(struct netfs_read_subrequest *subreq)
+{
+	netfs_put_read_request(subreq->rreq);
+	kfree(subreq);
+}
+
+/*
+ * Clear the unread part of an I/O request.
+ */
+static void netfs_clear_unread(struct netfs_read_subrequest *subreq)
+{
+	struct iov_iter iter;
+
+	iov_iter_xarray(&iter, WRITE, &subreq->rreq->mapping->i_pages,
+			subreq->start + subreq->transferred,
+			subreq->len   - subreq->transferred);
+	iov_iter_zero(iov_iter_count(&iter), &iter);
+}
+
+/*
+ * Fill a subrequest region with zeroes.
+ */
+static void netfs_fill_with_zeroes(struct netfs_read_request *rreq,
+				   struct netfs_read_subrequest *subreq)
+{
+	__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
+	netfs_subreq_terminated(subreq, 0);
+}
+
+/*
+ * Ask the netfs to issue a read request to the server for us.
+ *
+ * The netfs is expected to read from subreq->pos + subreq->transferred to
+ * subreq->pos + subreq->len - 1.  It may not backtrack and write data into the
+ * buffer prior to the transferred point as it might clobber dirty data
+ * obtained from the cache.
+ *
+ * Alternatively, the netfs is allowed to indicate one of two things:
+ *
+ * - NETFS_SREQ_SHORT_READ: A short read - it will get called again to try and
+ *   make progress.
+ *
+ * - NETFS_SREQ_CLEAR_TAIL: A short read - the rest of the buffer will be
+ *   cleared.
+ */
+static void netfs_read_from_server(struct netfs_read_request *rreq,
+				   struct netfs_read_subrequest *subreq)
+{
+	rreq->netfs_ops->issue_op(subreq);
+}
+
+/*
+ * Release those waiting.
+ */
+static void netfs_rreq_completed(struct netfs_read_request *rreq)
+{
+	netfs_rreq_clear_subreqs(rreq);
+	netfs_put_read_request(rreq);
+}
+
+/*
+ * Unlock the pages in a read operation.  We need to set PG_fscache on any
+ * pages we're going to write back before we unlock them.
+ */
+static void netfs_rreq_unlock(struct netfs_read_request *rreq)
+{
+	struct netfs_read_subrequest *subreq;
+	struct page *page;
+	unsigned int iopos, account = 0;
+	pgoff_t start_page = rreq->start / PAGE_SIZE;
+	pgoff_t last_page = ((rreq->start + rreq->len) / PAGE_SIZE) - 1;
+	bool subreq_failed = false;
+	int i;
+
+	XA_STATE(xas, &rreq->mapping->i_pages, start_page);
+
+	if (test_bit(NETFS_RREQ_FAILED, &rreq->flags)) {
+		__clear_bit(NETFS_RREQ_WRITE_TO_CACHE, &rreq->flags);
+		list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
+			__clear_bit(NETFS_SREQ_WRITE_TO_CACHE, &subreq->flags);
+		}
+	}
+
+	/* Walk through the pagecache and the I/O request lists simultaneously.
+	 * We may have a mixture of cached and uncached sections and we only
+	 * really want to write out the uncached sections.  This is slightly
+	 * complicated by the possibility that we might have huge pages with a
+	 * mixture inside.
+	 */
+	subreq = list_first_entry(&rreq->subrequests,
+				  struct netfs_read_subrequest, rreq_link);
+	iopos = 0;
+	subreq_failed = (subreq->error < 0);
+
+	rcu_read_lock();
+	xas_for_each(&xas, page, last_page) {
+		unsigned int pgpos = (page->index - start_page) * PAGE_SIZE;
+		unsigned int pgend = pgpos + thp_size(page);
+		bool pg_failed = false;
+
+		for (;;) {
+			if (test_bit(NETFS_SREQ_WRITE_TO_CACHE, &subreq->flags))
+				SetPageFsCache(page);
+			pg_failed |= subreq_failed;
+			if (pgend < iopos + subreq->len)
+				break;
+
+			account += subreq->transferred;
+			iopos += subreq->len;
+			if (!list_is_last(&subreq->rreq_link, &rreq->subrequests)) {
+				subreq = list_next_entry(subreq, rreq_link);
+				subreq_failed = (subreq->error < 0);
+			} else {
+				subreq = NULL;
+				subreq_failed = false;
+			}
+			if (pgend == iopos)
+				break;
+		}
+
+		if (!subreq_failed) {
+			for (i = 0; i < thp_nr_pages(page); i++)
+				flush_dcache_page(page);
+			SetPageUptodate(page);
+		}
+
+		if (!test_bit(NETFS_RREQ_DONT_UNLOCK_PAGES, &rreq->flags)) {
+			if (page->index == rreq->no_unlock_page &&
+			    test_bit(NETFS_RREQ_NO_UNLOCK_PAGE, &rreq->flags))
+				_debug("no unlock");
+			else
+				unlock_page(page);
+		}
+	}
+	rcu_read_unlock();
+
+	task_io_account_read(account);
+	if (rreq->netfs_ops->done)
+		rreq->netfs_ops->done(rreq);
+}
+
+/*
+ * Handle a short read.
+ */
+static void netfs_rreq_short_read(struct netfs_read_request *rreq,
+				  struct netfs_read_subrequest *subreq)
+{
+	__clear_bit(NETFS_SREQ_SHORT_READ, &subreq->flags);
+	__set_bit(NETFS_SREQ_SEEK_DATA_READ, &subreq->flags);
+
+	netfs_get_read_subrequest(subreq);
+	atomic_inc(&rreq->nr_rd_ops);
+	netfs_read_from_server(rreq, subreq);
+}
+
+/*
+ * Resubmit any short or failed operations.  Returns true if we got the rreq
+ * ref back.
+ */
+static bool netfs_rreq_perform_resubmissions(struct netfs_read_request *rreq)
+{
+	struct netfs_read_subrequest *subreq;
+
+	WARN_ON(in_softirq());
+
+	/* We don't want terminating submissions trying to wake us up whilst
+	 * we're still going through the list.
+	 */
+	atomic_inc(&rreq->nr_rd_ops);
+
+	__clear_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags);
+	list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
+		if (subreq->error) {
+			if (subreq->source != NETFS_READ_FROM_CACHE)
+				break;
+			subreq->source = NETFS_DOWNLOAD_FROM_SERVER;
+			subreq->error = 0;
+			netfs_get_read_subrequest(subreq);
+			atomic_inc(&rreq->nr_rd_ops);
+			netfs_read_from_server(rreq, subreq);
+		} else if (test_bit(NETFS_SREQ_SHORT_READ, &subreq->flags)) {
+			netfs_rreq_short_read(rreq, subreq);
+		}
+	}
+
+	/* If we decrement nr_rd_ops to 0, the usage ref belongs to us. */
+	if (atomic_dec_and_test(&rreq->nr_rd_ops))
+		return true;
+
+	wake_up_var(&rreq->nr_rd_ops);
+	return false;
+}
+
+/*
+ * Assess the state of a read request and decide what to do next.
+ *
+ * Note that we could be in an ordinary kernel thread, on a workqueue or in
+ * softirq context at this point.  We inherit a ref from the caller.
+ */
+static void netfs_rreq_assess(struct netfs_read_request *rreq)
+{
+again:
+	if (!test_bit(NETFS_RREQ_FAILED, &rreq->flags) &&
+	    test_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags)) {
+		if (netfs_rreq_perform_resubmissions(rreq))
+			goto again;
+		return;
+	}
+
+	netfs_rreq_unlock(rreq);
+
+	clear_bit_unlock(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
+	wake_up_bit(&rreq->flags, NETFS_RREQ_IN_PROGRESS);
+
+	netfs_rreq_completed(rreq);
+}
+
+static void netfs_rreq_work(struct work_struct *work)
+{
+	struct netfs_read_request *rreq =
+		container_of(work, struct netfs_read_request, work);
+	netfs_rreq_assess(rreq);
+}
+
+/*
+ * Handle the completion of all outstanding I/O operations on a read request.
+ * We inherit a ref from the caller.
+ */
+static void netfs_rreq_terminated(struct netfs_read_request *rreq)
+{
+	if (test_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags) &&
+	    in_softirq()) {
+		if (!queue_work(system_unbound_wq, &rreq->work))
+			BUG();
+	} else {
+		netfs_rreq_assess(rreq);
+	}
+}
+
+/**
+ * netfs_subreq_terminated - Note the termination of an I/O operation.
+ * @subreq: The I/O request that has terminated.
+ *
+ * This tells the read helper that a contributory I/O operation has terminated,
+ * one way or another, and that it should integrate the results.
+ *
+ * The caller must have set @subreq->transferred, @subreq->error and
+ * @subreq->flags as appropriate for the outcome of the operation.  The helper
+ * will look after reissuing I/O operations as appropriate and writing
+ * downloaded data to the cache.
+ *
+ * This may be called from a softirq handler, so we want to avoid taking the
+ * spinlock if we can.
+ */
+void netfs_subreq_terminated(struct netfs_read_subrequest *subreq,
+			     ssize_t transferred_or_error)
+{
+	struct netfs_read_request *rreq = subreq->rreq;
+	int u;
+
+	_enter("[%u]{%llx,%lx},%zd",
+	       subreq->debug_index, subreq->start, subreq->flags,
+	       transferred_or_error);
+
+	if (IS_ERR_VALUE(transferred_or_error)) {
+		subreq->error = transferred_or_error;
+		goto failed;
+	}
+
+	if (WARN_ON(transferred_or_error > subreq->len - subreq->transferred))
+		transferred_or_error = subreq->len - subreq->transferred;
+
+	subreq->error = 0;
+	subreq->transferred += transferred_or_error;
+	if (subreq->transferred < subreq->len)
+		goto incomplete;
+
+complete:
+	__clear_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags);
+	if (test_bit(NETFS_SREQ_WRITE_TO_CACHE, &subreq->flags))
+		set_bit(NETFS_RREQ_WRITE_TO_CACHE, &rreq->flags);
+
+out:
+	/* If we decrement nr_rd_ops to 0, the ref belongs to us. */
+	u = atomic_dec_return(&rreq->nr_rd_ops);
+	if (u == 0)
+		netfs_rreq_terminated(rreq);
+	else if (u == 1)
+		wake_up_var(&rreq->nr_rd_ops);
+
+	netfs_put_subrequest(subreq);
+	return;
+
+incomplete:
+	if (test_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags)) {
+		netfs_clear_unread(subreq);
+		subreq->transferred = subreq->len;
+		goto complete;
+	}
+
+	if (transferred_or_error == 0) {
+		if (__test_and_set_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags)) {
+			subreq->error = -ENODATA;
+			goto failed;
+		}
+	} else {
+		__clear_bit(NETFS_SREQ_NO_PROGRESS, &subreq->flags);
+	}
+
+	__set_bit(NETFS_SREQ_SHORT_READ, &subreq->flags);
+	set_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags);
+	goto out;
+
+failed:
+	if (subreq->source == NETFS_READ_FROM_CACHE) {
+		set_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags);
+	} else {
+		set_bit(NETFS_RREQ_FAILED, &rreq->flags);
+		rreq->error = subreq->error;
+	}
+	goto out;
+}
+EXPORT_SYMBOL(netfs_subreq_terminated);
+
+static enum netfs_read_source netfs_cache_prepare_read(struct netfs_read_subrequest *subreq,
+						       loff_t i_size)
+{
+	struct netfs_read_request *rreq = subreq->rreq;
+
+	if (subreq->start >= rreq->i_size)
+		return NETFS_FILL_WITH_ZEROES;
+	return NETFS_DOWNLOAD_FROM_SERVER;
+}
+
+/*
+ * Work out what sort of subrequest the next one will be.
+ */
+static enum netfs_read_source
+netfs_rreq_prepare_read(struct netfs_read_request *rreq,
+			struct netfs_read_subrequest *subreq)
+{
+	enum netfs_read_source source;
+
+	_enter("%llx-%llx,%llx", subreq->start, subreq->start + subreq->len, rreq->i_size);
+
+	source = netfs_cache_prepare_read(subreq, rreq->i_size);
+	if (source == NETFS_INVALID_READ)
+		goto out;
+
+	if (source == NETFS_DOWNLOAD_FROM_SERVER) {
+		/* Call out to the netfs to let it shrink the request to fit
+		 * its own I/O sizes and boundaries.  If it shinks it here, it
+		 * will be called again to make simultaneous calls; if it wants
+		 * to make serial calls, it can indicate a short read and then
+		 * we will call it again.
+		 */
+		if (subreq->len > rreq->i_size - subreq->start)
+			subreq->len = rreq->i_size - subreq->start;
+
+		if (rreq->netfs_ops->clamp_length &&
+		    !rreq->netfs_ops->clamp_length(subreq)) {
+			source = NETFS_INVALID_READ;
+			goto out;
+		}
+	}
+
+	if (WARN_ON(subreq->len == 0))
+		source = NETFS_INVALID_READ;
+
+out:
+	subreq->source = source;
+	return source;
+}
+
+/*
+ * Slice off a piece of a read request and submit an I/O request for it.
+ */
+static bool netfs_rreq_submit_slice(struct netfs_read_request *rreq,
+				    unsigned int *_debug_index)
+{
+	struct netfs_read_subrequest *subreq;
+	enum netfs_read_source source;
+
+	subreq = netfs_alloc_subrequest(rreq);
+	if (!subreq)
+		return false;
+
+	subreq->debug_index	= (*_debug_index)++;
+	subreq->start		= rreq->start + rreq->submitted;
+	subreq->len		= rreq->len   - rreq->submitted;
+
+	_debug("slice %llx,%zx,%zx", subreq->start, subreq->len, rreq->submitted);
+
+	/* Call out to the cache to find out what it can do with the remaining
+	 * subset.  It tells us in subreq->flags what it decided should be done
+	 * and adjusts subreq->len down if the subset crosses a cache boundary.
+	 *
+	 * Then when we hand the subset, it can choose to take a subset of that
+	 * (the starts must coincide), in which case, we go around the loop
+	 * again and ask it to download the next piece.
+	 */
+	source = netfs_rreq_prepare_read(rreq, subreq);
+	if (source == NETFS_INVALID_READ)
+		goto subreq_failed;
+
+	netfs_get_read_request(rreq);
+	atomic_inc(&rreq->nr_rd_ops);
+	list_add_tail(&subreq->rreq_link, &rreq->subrequests);
+
+	rreq->submitted += subreq->len;
+
+	switch (source) {
+	case NETFS_FILL_WITH_ZEROES:
+		netfs_fill_with_zeroes(rreq, subreq);
+		break;
+	case NETFS_DOWNLOAD_FROM_SERVER:
+		netfs_read_from_server(rreq, subreq);
+		break;
+	default:
+		BUG();
+	}
+
+	return true;
+
+subreq_failed:
+	netfs_put_subrequest(subreq);
+	netfs_put_subrequest(subreq);
+	return false;
+}
+
+static void netfs_rreq_expand(struct netfs_read_request *rreq,
+			      struct readahead_control *ractl)
+{
+	/* Give the netfs a chance to change the request parameters.  The
+	 * resultant request must contain the original region.
+	 */
+	if (rreq->netfs_ops->expand_readahead)
+		rreq->netfs_ops->expand_readahead(rreq);
+
+	/* Expand the request if the cache wants it to start earlier.  Note
+	 * that the expansion may get further extended if the VM wishes to
+	 * insert THPs and the preferred start and/or end wind up in the middle
+	 * of THPs.
+	 *
+	 * If this is the case, however, the THP size should be an integer
+	 * multiple of the cache granule size, so we get a whole number of
+	 * granules to deal with.
+	 */
+	if (rreq->start  != readahead_pos(ractl) ||
+	    rreq->len != readahead_length(ractl)) {
+		readahead_expand(ractl, rreq->start, rreq->len);
+		rreq->start  = readahead_pos(ractl);
+		rreq->len = readahead_length(ractl);
+	}
+}
+
+/**
+ * netfs_readahead - Helper to manage a read request
+ * @ractl: The description of the readahead request
+ * @ops: The network filesystem's operations for the helper to use
+ * @netfs_priv: Private netfs data to be retained in the request
+ *
+ * Fulfil a readahead request by drawing data from the cache if possible, or
+ * the netfs if not.  Space beyond the EOF is zero-filled.  Multiple I/O
+ * requests from different sources will get munged together.  If necessary, the
+ * readahead window can be expanded in either direction to a more convenient
+ * alighment for RPC efficiency or to make storage in the cache feasible.
+ *
+ * The calling netfs must provide a table of operations, only one of which,
+ * issue_op, is mandatory.  It may also be passed a private token, which will
+ * be retained in rreq->netfs_priv and will be cleaned up by ops->cleanup().
+ *
+ * This is usable whether or not caching is enabled.
+ */
+void netfs_readahead(struct readahead_control *ractl,
+		     const struct netfs_read_request_ops *ops,
+		     void *netfs_priv)
+{
+	struct netfs_read_request *rreq;
+	struct page *page;
+	unsigned int debug_index = 0;
+
+	_enter("%lx,%x", readahead_index(ractl), readahead_count(ractl));
+
+	if (readahead_count(ractl) == 0)
+		goto cleanup;
+
+	rreq = netfs_alloc_read_request(ops, netfs_priv, ractl->file);
+	if (!rreq)
+		goto cleanup;
+	rreq->mapping	= ractl->mapping;
+	rreq->start	= readahead_pos(ractl);
+	rreq->len	= readahead_length(ractl);
+
+	netfs_rreq_expand(rreq, ractl);
+
+	atomic_set(&rreq->nr_rd_ops, 1);
+	do {
+		if (!netfs_rreq_submit_slice(rreq, &debug_index))
+			break;
+
+	} while (rreq->submitted < rreq->len);
+
+	if (rreq->submitted == 0) {
+		netfs_put_read_request(rreq);
+		return;
+	}
+
+	// TODO: If we didn't submit enough readage, we need to try punting to
+	// a work queue.
+
+	while ((page = readahead_page(ractl)))
+		put_page(page);
+
+	/* If we decrement nr_rd_ops to 0, the ref belongs to us. */
+	if (atomic_dec_and_test(&rreq->nr_rd_ops))
+		netfs_rreq_assess(rreq);
+	return;
+
+cleanup:
+	if (netfs_priv)
+		ops->cleanup(ractl->mapping, netfs_priv);
+	return;
+}
+EXPORT_SYMBOL(netfs_readahead);
+
+/**
+ * netfs_page - Helper to manage a readpage request
+ * @file: The file to read from
+ * @page: The page to read
+ * @ops: The network filesystem's operations for the helper to use
+ * @netfs_priv: Private netfs data to be retained in the request
+ *
+ * Fulfil a readpage request by drawing data from the cache if possible, or the
+ * netfs if not.  Space beyond the EOF is zero-filled.  Multiple I/O requests
+ * from different sources will get munged together.
+ *
+ * The calling netfs must provide a table of operations, only one of which,
+ * issue_op, is mandatory.  It may also be passed a private token, which will
+ * be retained in rreq->netfs_priv and will be cleaned up by ops->cleanup().
+ *
+ * This is usable whether or not caching is enabled.
+ */
+int netfs_readpage(struct file *file,
+		   struct page *page,
+		   const struct netfs_read_request_ops *ops,
+		   void *netfs_priv)
+{
+	struct netfs_read_request *rreq;
+	unsigned int debug_index = 0;
+	int ret;
+
+	_enter("%lx", page->index);
+
+	rreq = netfs_alloc_read_request(ops, netfs_priv, file);
+	if (!rreq) {
+		if (netfs_priv)
+			ops->cleanup(netfs_priv, page->mapping);
+		unlock_page(page);
+		return -ENOMEM;
+	}
+	rreq->mapping	= page->mapping;
+	rreq->start	= page->index * PAGE_SIZE;
+	rreq->len	= thp_size(page);
+
+	netfs_get_read_request(rreq);
+
+	atomic_set(&rreq->nr_rd_ops, 1);
+	do {
+		if (!netfs_rreq_submit_slice(rreq, &debug_index))
+			break;
+
+	} while (rreq->submitted < rreq->len);
+
+	// TODO: If we didn't submit enough readage, we need to clean up
+
+	/* Keep nr_rd_ops incremented so that the ref always belongs to us, and
+	 * the service code isn't punted off to a random thread pool to
+	 * process.
+	 */
+	do {
+		wait_var_event(&rreq->nr_rd_ops, atomic_read(&rreq->nr_rd_ops) == 1);
+		netfs_rreq_assess(rreq);
+	} while (test_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags));
+
+	ret = rreq->error;
+	netfs_put_read_request(rreq);
+	return ret;
+}
+EXPORT_SYMBOL(netfs_readpage);
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index a1c928fe98e7..1f8dc72369ee 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -19,6 +19,7 @@
 #include <linux/pagemap.h>
 #include <linux/pagevec.h>
 #include <linux/list_bl.h>
+#include <linux/netfs.h>
 
 #if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
 #define fscache_available() (1)
@@ -29,16 +30,6 @@
 #endif
 
 
-/*
- * overload PG_private_2 to give us PG_fscache - this is used to indicate that
- * a page is currently backed by a local disk cache
- */
-#define PageFsCache(page)		PagePrivate2((page))
-#define SetPageFsCache(page)		SetPagePrivate2((page))
-#define ClearPageFsCache(page)		ClearPagePrivate2((page))
-#define TestSetPageFsCache(page)	TestSetPagePrivate2((page))
-#define TestClearPageFsCache(page)	TestClearPagePrivate2((page))
-
 /* pattern used to fill dead space in an index entry */
 #define FSCACHE_INDEX_DEADFILL_PATTERN 0x79
 
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
new file mode 100644
index 000000000000..8d27ad82e0c3
--- /dev/null
+++ b/include/linux/netfs.h
@@ -0,0 +1,108 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Network filesystem support services.
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * See: Documentation/filesystems/caching/netfs-support.rst
+ *
+ * for a description of the network filesystem interface declared here.
+ */
+
+#ifndef _LINUX_NETFS_H
+#define _LINUX_NETFS_H
+
+#include <linux/workqueue.h>
+#include <linux/fs.h>
+
+/*
+ * Overload PG_private_2 to give us PG_fscache - this is used to indicate that
+ * a page is currently backed by a local disk cache
+ */
+#define PageFsCache(page)		PagePrivate2((page))
+#define SetPageFsCache(page)		SetPagePrivate2((page))
+#define ClearPageFsCache(page)		ClearPagePrivate2((page))
+#define TestSetPageFsCache(page)	TestSetPagePrivate2((page))
+#define TestClearPageFsCache(page)	TestClearPagePrivate2((page))
+
+enum netfs_read_source {
+	NETFS_FILL_WITH_ZEROES,
+	NETFS_DOWNLOAD_FROM_SERVER,
+	NETFS_READ_FROM_CACHE,
+	NETFS_INVALID_READ,
+} __mode(byte);
+
+/*
+ * Descriptor for a single component subrequest.
+ */
+struct netfs_read_subrequest {
+	struct netfs_read_request *rreq;	/* Supervising read request */
+	struct list_head	rreq_link;	/* Link in rreq->subrequests */
+	loff_t			start;		/* Where to start the I/O */
+	size_t			len;		/* Size of the I/O */
+	size_t			transferred;	/* Amount of data transferred */
+	refcount_t		usage;
+	short			error;		/* 0 or error that occurred */
+	unsigned short		debug_index;	/* Index in list (for debugging output) */
+	enum netfs_read_source	source;		/* Where to read from */
+	unsigned long		flags;
+#define NETFS_SREQ_WRITE_TO_CACHE	0	/* Set if should write to cache */
+#define NETFS_SREQ_CLEAR_TAIL		1	/* Set if the rest of the read should be cleared */
+#define NETFS_SREQ_SHORT_READ		2	/* Set if there was a short read from the cache */
+#define NETFS_SREQ_SEEK_DATA_READ	3	/* Set if ->read() should SEEK_DATA first */
+#define NETFS_SREQ_NO_PROGRESS		4	/* Set if we didn't manage to read any data */
+};
+
+/*
+ * Descriptor for a read helper request.  This is used to make multiple I/O
+ * requests on a variety of sources and then stitch the result together.
+ */
+struct netfs_read_request {
+	struct work_struct	work;
+	struct inode		*inode;		/* The file being accessed */
+	struct address_space	*mapping;	/* The mapping being accessed */
+	struct list_head	subrequests;	/* Requests to fetch I/O from disk or net */
+	void			*netfs_priv;	/* Private data for the netfs */
+	atomic_t		nr_rd_ops;	/* Number of read ops in progress */
+	size_t			submitted;	/* Amount submitted for I/O so far */
+	size_t			len;		/* Length of the request */
+	short			error;		/* 0 or error that occurred */
+	loff_t			i_size;		/* Size of the file */
+	loff_t			start;		/* Start position */
+	pgoff_t			no_unlock_page;	/* Don't unlock this page after read */
+	refcount_t		usage;
+	unsigned long		flags;
+#define NETFS_RREQ_INCOMPLETE_IO	0	/* Some ioreqs terminated short or with error */
+#define NETFS_RREQ_WRITE_TO_CACHE	1	/* Need to write to the cache */
+#define NETFS_RREQ_NO_UNLOCK_PAGE	2	/* Don't unlock no_unlock_page on completion */
+#define NETFS_RREQ_DONT_UNLOCK_PAGES	3	/* Don't unlock the pages on completion */
+#define NETFS_RREQ_FAILED		4	/* The request failed */
+#define NETFS_RREQ_IN_PROGRESS		5	/* Unlocked when the request completes */
+	const struct netfs_read_request_ops *netfs_ops;
+};
+
+/*
+ * Operations the network filesystem can/must provide to the helpers.
+ */
+struct netfs_read_request_ops {
+	void (*init_rreq)(struct netfs_read_request *rreq, struct file *file);
+	void (*expand_readahead)(struct netfs_read_request *rreq);
+	bool (*clamp_length)(struct netfs_read_subrequest *subreq);
+	void (*issue_op)(struct netfs_read_subrequest *subreq);
+	bool (*is_still_valid)(struct netfs_read_request *rreq);
+	void (*done)(struct netfs_read_request *rreq);
+	void (*cleanup)(struct address_space *mapping, void *netfs_priv);
+};
+
+struct readahead_control;
+extern void netfs_readahead(struct readahead_control *,
+			    const struct netfs_read_request_ops *,
+			    void *);
+extern int netfs_readpage(struct file *,
+			  struct page *,
+			  const struct netfs_read_request_ops *,
+			  void *);
+
+extern void netfs_subreq_terminated(struct netfs_read_subrequest *, ssize_t);
+
+#endif /* _LINUX_NETFS_H */



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 07/32] netfs: Add tracepoints
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (5 preceding siblings ...)
  2021-01-25 21:32 ` [PATCH 06/32] netfs: Provide readahead and readpage netfs helpers David Howells
@ 2021-01-25 21:32 ` David Howells
  2021-01-25 21:32 ` [PATCH 08/32] netfs: Gather stats David Howells
                   ` (24 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:32 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Add three tracepoints to track the activity of the read helpers:

 (1) netfs/netfs_read

     This logs entry to the read helpers and also expansion of the range in
     a readahead request.

 (2) netfs/netfs_rreq

     This logs the progress of netfs_read_request objects which track
     read requests.  A read request may be a compound of multiple
     subrequests.

 (3) netfs/netfs_sreq

     This logs the progress of netfs_read_subrequest objects, which track
     the contributions from various sources to a read request.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/netfs/read_helper.c       |   28 ++++++
 include/linux/netfs.h        |    2 
 include/trace/events/netfs.h |  199 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 229 insertions(+)
 create mode 100644 include/trace/events/netfs.h

diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
index e5264e9d8912..2a90314ea36f 100644
--- a/fs/netfs/read_helper.c
+++ b/fs/netfs/read_helper.c
@@ -16,6 +16,8 @@
 #include <linux/task_io_accounting_ops.h>
 #include <linux/netfs.h>
 #include "internal.h"
+#define CREATE_TRACE_POINTS
+#include <trace/events/netfs.h>
 
 MODULE_DESCRIPTION("Network fs support");
 MODULE_AUTHOR("Red Hat, Inc.");
@@ -38,6 +40,7 @@ static struct netfs_read_request *netfs_alloc_read_request(
 	const struct netfs_read_request_ops *ops, void *netfs_priv,
 	struct file *file)
 {
+	static atomic_t debug_ids;
 	struct netfs_read_request *rreq;
 
 	rreq = kzalloc(sizeof(struct netfs_read_request), GFP_KERNEL);
@@ -46,6 +49,7 @@ static struct netfs_read_request *netfs_alloc_read_request(
 		rreq->netfs_priv = netfs_priv;
 		rreq->inode	= file_inode(file);
 		rreq->i_size	= i_size_read(rreq->inode);
+		rreq->debug_id	= atomic_inc_return(&debug_ids);
 		INIT_LIST_HEAD(&rreq->subrequests);
 		INIT_WORK(&rreq->work, netfs_rreq_work);
 		refcount_set(&rreq->usage, 1);
@@ -80,6 +84,7 @@ static void netfs_free_read_request(struct work_struct *work)
 	netfs_rreq_clear_subreqs(rreq);
 	if (rreq->netfs_priv)
 		rreq->netfs_ops->cleanup(rreq->mapping, rreq->netfs_priv);
+	trace_netfs_rreq(rreq, netfs_rreq_trace_free);
 	kfree(rreq);
 }
 
@@ -121,6 +126,7 @@ static void netfs_get_read_subrequest(struct netfs_read_subrequest *subreq)
 
 static void __netfs_put_subrequest(struct netfs_read_subrequest *subreq)
 {
+	trace_netfs_sreq(subreq, netfs_sreq_trace_free);
 	netfs_put_read_request(subreq->rreq);
 	kfree(subreq);
 }
@@ -175,6 +181,7 @@ static void netfs_read_from_server(struct netfs_read_request *rreq,
  */
 static void netfs_rreq_completed(struct netfs_read_request *rreq)
 {
+	trace_netfs_rreq(rreq, netfs_rreq_trace_done);
 	netfs_rreq_clear_subreqs(rreq);
 	netfs_put_read_request(rreq);
 }
@@ -213,6 +220,8 @@ static void netfs_rreq_unlock(struct netfs_read_request *rreq)
 	iopos = 0;
 	subreq_failed = (subreq->error < 0);
 
+	trace_netfs_rreq(rreq, netfs_rreq_trace_unlock);
+
 	rcu_read_lock();
 	xas_for_each(&xas, page, last_page) {
 		unsigned int pgpos = (page->index - start_page) * PAGE_SIZE;
@@ -269,6 +278,8 @@ static void netfs_rreq_short_read(struct netfs_read_request *rreq,
 	__clear_bit(NETFS_SREQ_SHORT_READ, &subreq->flags);
 	__set_bit(NETFS_SREQ_SEEK_DATA_READ, &subreq->flags);
 
+	trace_netfs_sreq(subreq, netfs_sreq_trace_resubmit_short);
+
 	netfs_get_read_subrequest(subreq);
 	atomic_inc(&rreq->nr_rd_ops);
 	netfs_read_from_server(rreq, subreq);
@@ -284,6 +295,8 @@ static bool netfs_rreq_perform_resubmissions(struct netfs_read_request *rreq)
 
 	WARN_ON(in_softirq());
 
+	trace_netfs_rreq(rreq, netfs_rreq_trace_resubmit);
+
 	/* We don't want terminating submissions trying to wake us up whilst
 	 * we're still going through the list.
 	 */
@@ -296,6 +309,7 @@ static bool netfs_rreq_perform_resubmissions(struct netfs_read_request *rreq)
 				break;
 			subreq->source = NETFS_DOWNLOAD_FROM_SERVER;
 			subreq->error = 0;
+			trace_netfs_sreq(subreq, netfs_sreq_trace_download_instead);
 			netfs_get_read_subrequest(subreq);
 			atomic_inc(&rreq->nr_rd_ops);
 			netfs_read_from_server(rreq, subreq);
@@ -320,6 +334,8 @@ static bool netfs_rreq_perform_resubmissions(struct netfs_read_request *rreq)
  */
 static void netfs_rreq_assess(struct netfs_read_request *rreq)
 {
+	trace_netfs_rreq(rreq, netfs_rreq_trace_assess);
+
 again:
 	if (!test_bit(NETFS_RREQ_FAILED, &rreq->flags) &&
 	    test_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags)) {
@@ -402,6 +418,8 @@ void netfs_subreq_terminated(struct netfs_read_subrequest *subreq,
 		set_bit(NETFS_RREQ_WRITE_TO_CACHE, &rreq->flags);
 
 out:
+	trace_netfs_sreq(subreq, netfs_sreq_trace_terminated);
+
 	/* If we decrement nr_rd_ops to 0, the ref belongs to us. */
 	u = atomic_dec_return(&rreq->nr_rd_ops);
 	if (u == 0)
@@ -490,6 +508,7 @@ netfs_rreq_prepare_read(struct netfs_read_request *rreq,
 
 out:
 	subreq->source = source;
+	trace_netfs_sreq(subreq, netfs_sreq_trace_prepare);
 	return source;
 }
 
@@ -530,6 +549,7 @@ static bool netfs_rreq_submit_slice(struct netfs_read_request *rreq,
 
 	rreq->submitted += subreq->len;
 
+	trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
 	switch (source) {
 	case NETFS_FILL_WITH_ZEROES:
 		netfs_fill_with_zeroes(rreq, subreq);
@@ -572,6 +592,9 @@ static void netfs_rreq_expand(struct netfs_read_request *rreq,
 		readahead_expand(ractl, rreq->start, rreq->len);
 		rreq->start  = readahead_pos(ractl);
 		rreq->len = readahead_length(ractl);
+
+		trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
+				 netfs_read_trace_expanded);
 	}
 }
 
@@ -613,6 +636,9 @@ void netfs_readahead(struct readahead_control *ractl,
 	rreq->start	= readahead_pos(ractl);
 	rreq->len	= readahead_length(ractl);
 
+	trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
+			 netfs_read_trace_readahead);
+
 	netfs_rreq_expand(rreq, ractl);
 
 	atomic_set(&rreq->nr_rd_ops, 1);
@@ -684,6 +710,8 @@ int netfs_readpage(struct file *file,
 	rreq->start	= page->index * PAGE_SIZE;
 	rreq->len	= thp_size(page);
 
+	trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_readpage);
+
 	netfs_get_read_request(rreq);
 
 	atomic_set(&rreq->nr_rd_ops, 1);
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 8d27ad82e0c3..0779cf082101 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -63,6 +63,8 @@ struct netfs_read_request {
 	struct address_space	*mapping;	/* The mapping being accessed */
 	struct list_head	subrequests;	/* Requests to fetch I/O from disk or net */
 	void			*netfs_priv;	/* Private data for the netfs */
+	unsigned int		debug_id;
+	unsigned int		cookie_debug_id;
 	atomic_t		nr_rd_ops;	/* Number of read ops in progress */
 	size_t			submitted;	/* Amount submitted for I/O so far */
 	size_t			len;		/* Length of the request */
diff --git a/include/trace/events/netfs.h b/include/trace/events/netfs.h
new file mode 100644
index 000000000000..12ad382764c5
--- /dev/null
+++ b/include/trace/events/netfs.h
@@ -0,0 +1,199 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Network filesystem support module tracepoints
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM netfs
+
+#if !defined(_TRACE_NETFS_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_NETFS_H
+
+#include <linux/tracepoint.h>
+
+/*
+ * Define enums for tracing information.
+ */
+#ifndef __NETFS_DECLARE_TRACE_ENUMS_ONCE_ONLY
+#define __NETFS_DECLARE_TRACE_ENUMS_ONCE_ONLY
+
+enum netfs_read_trace {
+	netfs_read_trace_expanded,
+	netfs_read_trace_readahead,
+	netfs_read_trace_readpage,
+};
+
+enum netfs_rreq_trace {
+	netfs_rreq_trace_assess,
+	netfs_rreq_trace_done,
+	netfs_rreq_trace_free,
+	netfs_rreq_trace_resubmit,
+	netfs_rreq_trace_unlock,
+	netfs_rreq_trace_unmark,
+	netfs_rreq_trace_write,
+};
+
+enum netfs_sreq_trace {
+	netfs_sreq_trace_download_instead,
+	netfs_sreq_trace_free,
+	netfs_sreq_trace_prepare,
+	netfs_sreq_trace_resubmit_short,
+	netfs_sreq_trace_submit,
+	netfs_sreq_trace_terminated,
+	netfs_sreq_trace_write,
+	netfs_sreq_trace_write_term,
+};
+
+#endif
+
+#define netfs_read_traces					\
+	EM(netfs_read_trace_expanded,		"EXPANDED ")	\
+	EM(netfs_read_trace_readahead,		"READAHEAD")	\
+	E_(netfs_read_trace_readpage,		"READPAGE ")
+
+#define netfs_rreq_traces					\
+	EM(netfs_rreq_trace_assess,		"ASSESS")	\
+	EM(netfs_rreq_trace_done,		"DONE  ")	\
+	EM(netfs_rreq_trace_free,		"FREE  ")	\
+	EM(netfs_rreq_trace_resubmit,		"RESUBM")	\
+	EM(netfs_rreq_trace_unlock,		"UNLOCK")	\
+	EM(netfs_rreq_trace_unmark,		"UNMARK")	\
+	E_(netfs_rreq_trace_write,		"WRITE ")
+
+#define netfs_sreq_sources					\
+	EM(NETFS_FILL_WITH_ZEROES,		"ZERO")		\
+	EM(NETFS_DOWNLOAD_FROM_SERVER,		"DOWN")		\
+	EM(NETFS_READ_FROM_CACHE,		"READ")		\
+	E_(NETFS_INVALID_READ,			"INVL")		\
+
+#define netfs_sreq_traces					\
+	EM(netfs_sreq_trace_download_instead,	"RDOWN")	\
+	EM(netfs_sreq_trace_free,		"FREE ")	\
+	EM(netfs_sreq_trace_prepare,		"PREP ")	\
+	EM(netfs_sreq_trace_resubmit_short,	"SHORT")	\
+	EM(netfs_sreq_trace_submit,		"SUBMT")	\
+	EM(netfs_sreq_trace_terminated,		"TERM ")	\
+	EM(netfs_sreq_trace_write,		"WRITE")	\
+	E_(netfs_sreq_trace_write_term,		"WTERM")
+
+
+/*
+ * Export enum symbols via userspace.
+ */
+#undef EM
+#undef E_
+#define EM(a, b) TRACE_DEFINE_ENUM(a);
+#define E_(a, b) TRACE_DEFINE_ENUM(a);
+
+netfs_read_traces;
+netfs_rreq_traces;
+netfs_sreq_sources;
+netfs_sreq_traces;
+
+/*
+ * Now redefine the EM() and E_() macros to map the enums to the strings that
+ * will be printed in the output.
+ */
+#undef EM
+#undef E_
+#define EM(a, b)	{ a, b },
+#define E_(a, b)	{ a, b }
+
+TRACE_EVENT(netfs_read,
+	    TP_PROTO(struct netfs_read_request *rreq,
+		     loff_t start, size_t len,
+		     enum netfs_read_trace what),
+
+	    TP_ARGS(rreq, start, len, what),
+
+	    TP_STRUCT__entry(
+		    __field(unsigned int,		rreq		)
+		    __field(unsigned int,		cookie		)
+		    __field(loff_t,			start		)
+		    __field(size_t,			len		)
+		    __field(enum netfs_read_trace,	what		)
+			     ),
+
+	    TP_fast_assign(
+		    __entry->rreq	= rreq->debug_id;
+		    __entry->cookie	= rreq->cookie_debug_id;
+		    __entry->start	= start;
+		    __entry->len	= len;
+		    __entry->what	= what;
+			   ),
+
+	    TP_printk("R=%08x %s c=%08x s=%llx %zx",
+		      __entry->rreq,
+		      __print_symbolic(__entry->what, netfs_read_traces),
+		      __entry->cookie,
+		      __entry->start, __entry->len)
+	    );
+
+TRACE_EVENT(netfs_rreq,
+	    TP_PROTO(struct netfs_read_request *rreq,
+		     enum netfs_rreq_trace what),
+
+	    TP_ARGS(rreq, what),
+
+	    TP_STRUCT__entry(
+		    __field(unsigned int,		rreq		)
+		    __field(unsigned short,		flags		)
+		    __field(enum netfs_rreq_trace,	what		)
+			     ),
+
+	    TP_fast_assign(
+		    __entry->rreq	= rreq->debug_id;
+		    __entry->flags	= rreq->flags;
+		    __entry->what	= what;
+			   ),
+
+	    TP_printk("R=%08x %s f=%02x",
+		      __entry->rreq,
+		      __print_symbolic(__entry->what, netfs_rreq_traces),
+		      __entry->flags)
+	    );
+
+TRACE_EVENT(netfs_sreq,
+	    TP_PROTO(struct netfs_read_subrequest *sreq,
+		     enum netfs_sreq_trace what),
+
+	    TP_ARGS(sreq, what),
+
+	    TP_STRUCT__entry(
+		    __field(unsigned int,		rreq		)
+		    __field(unsigned short,		index		)
+		    __field(short,			error		)
+		    __field(unsigned short,		flags		)
+		    __field(enum netfs_read_source,	source		)
+		    __field(enum netfs_sreq_trace,	what		)
+		    __field(size_t,			len		)
+		    __field(size_t,			transferred	)
+		    __field(loff_t,			start		)
+			     ),
+
+	    TP_fast_assign(
+		    __entry->rreq	= sreq->rreq->debug_id;
+		    __entry->index	= sreq->debug_index;
+		    __entry->error	= sreq->error;
+		    __entry->flags	= sreq->flags;
+		    __entry->source	= sreq->source;
+		    __entry->what	= what;
+		    __entry->len	= sreq->len;
+		    __entry->transferred = sreq->transferred;
+		    __entry->start	= sreq->start;
+			   ),
+
+	    TP_printk("R=%08x[%u] %s %s f=%02x s=%llx %zx/%zx e=%d",
+		      __entry->rreq, __entry->index,
+		      __print_symbolic(__entry->what, netfs_sreq_traces),
+		      __print_symbolic(__entry->source, netfs_sreq_sources),
+		      __entry->flags,
+		      __entry->start, __entry->transferred, __entry->len,
+		      __entry->error)
+	    );
+
+#endif /* _TRACE_NETFS_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 08/32] netfs: Gather stats
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (6 preceding siblings ...)
  2021-01-25 21:32 ` [PATCH 07/32] netfs: Add tracepoints David Howells
@ 2021-01-25 21:32 ` David Howells
  2021-01-25 21:32 ` [PATCH 09/32] netfs: Add write_begin helper David Howells
                   ` (23 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:32 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Gather statistics from the netfs interface that can be exported through a
seqfile.  This is intended to be called by a later patch when viewing
/proc/fs/fscache/stats.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/netfs/Kconfig       |   15 +++++++++++++
 fs/netfs/Makefile      |    3 +--
 fs/netfs/internal.h    |   34 ++++++++++++++++++++++++++++++
 fs/netfs/read_helper.c |   23 ++++++++++++++++++++
 fs/netfs/stats.c       |   54 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/netfs.h  |    1 +
 6 files changed, 128 insertions(+), 2 deletions(-)
 create mode 100644 fs/netfs/stats.c

diff --git a/fs/netfs/Kconfig b/fs/netfs/Kconfig
index 2ebf90e6ca95..578112713703 100644
--- a/fs/netfs/Kconfig
+++ b/fs/netfs/Kconfig
@@ -6,3 +6,18 @@ config NETFS_SUPPORT
 	  This option enables support for network filesystems, including
 	  helpers for high-level buffered I/O, abstracting out read
 	  segmentation, local caching and transparent huge page support.
+
+config NETFS_STATS
+	bool "Gather statistical information on local caching"
+	depends on NETFS_SUPPORT && PROC_FS
+	help
+	  This option causes statistical information to be gathered on local
+	  caching and exported through file:
+
+		/proc/fs/fscache/stats
+
+	  The gathering of statistics adds a certain amount of overhead to
+	  execution as there are a quite a few stats gathered, and on a
+	  multi-CPU system these may be on cachelines that keep bouncing
+	  between CPUs.  On the other hand, the stats are very useful for
+	  debugging purposes.  Saying 'Y' here is recommended.
diff --git a/fs/netfs/Makefile b/fs/netfs/Makefile
index 4b4eff2ba369..c15bfc966d96 100644
--- a/fs/netfs/Makefile
+++ b/fs/netfs/Makefile
@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
 
-netfs-y := \
-	read_helper.o
+netfs-y := read_helper.o stats.o
 
 obj-$(CONFIG_NETFS_SUPPORT) := netfs.o
diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h
index ee665c0e7dc8..98b6f4516da1 100644
--- a/fs/netfs/internal.h
+++ b/fs/netfs/internal.h
@@ -16,8 +16,42 @@
  */
 extern unsigned int netfs_debug;
 
+/*
+ * stats.c
+ */
+#ifdef CONFIG_NETFS_STATS
+extern atomic_t netfs_n_rh_readahead;
+extern atomic_t netfs_n_rh_readpage;
+extern atomic_t netfs_n_rh_rreq;
+extern atomic_t netfs_n_rh_sreq;
+extern atomic_t netfs_n_rh_download;
+extern atomic_t netfs_n_rh_download_done;
+extern atomic_t netfs_n_rh_download_failed;
+extern atomic_t netfs_n_rh_download_instead;
+extern atomic_t netfs_n_rh_read;
+extern atomic_t netfs_n_rh_read_done;
+extern atomic_t netfs_n_rh_read_failed;
+extern atomic_t netfs_n_rh_zero;
+extern atomic_t netfs_n_rh_short_read;
+extern atomic_t netfs_n_rh_write;
+extern atomic_t netfs_n_rh_write_done;
+extern atomic_t netfs_n_rh_write_failed;
+
+
+static inline void netfs_stat(atomic_t *stat)
+{
+	atomic_inc(stat);
+}
+
+static inline void netfs_stat_d(atomic_t *stat)
+{
+	atomic_dec(stat);
+}
+
+#else
 #define netfs_stat(x) do {} while(0)
 #define netfs_stat_d(x) do {} while(0)
+#endif
 
 /*****************************************************************************/
 /*
diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
index 2a90314ea36f..275ac37e2834 100644
--- a/fs/netfs/read_helper.c
+++ b/fs/netfs/read_helper.c
@@ -55,6 +55,7 @@ static struct netfs_read_request *netfs_alloc_read_request(
 		refcount_set(&rreq->usage, 1);
 		__set_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
 		ops->init_rreq(rreq, file);
+		netfs_stat(&netfs_n_rh_rreq);
 	}
 
 	return rreq;
@@ -86,6 +87,7 @@ static void netfs_free_read_request(struct work_struct *work)
 		rreq->netfs_ops->cleanup(rreq->mapping, rreq->netfs_priv);
 	trace_netfs_rreq(rreq, netfs_rreq_trace_free);
 	kfree(rreq);
+	netfs_stat_d(&netfs_n_rh_rreq);
 }
 
 static void netfs_put_read_request(struct netfs_read_request *rreq)
@@ -114,6 +116,7 @@ static struct netfs_read_subrequest *netfs_alloc_subrequest(
 		INIT_LIST_HEAD(&subreq->rreq_link);
 		refcount_set(&subreq->usage, 2);
 		subreq->rreq = rreq;
+		netfs_stat(&netfs_n_rh_sreq);
 	}
 
 	return subreq;
@@ -129,6 +132,7 @@ static void __netfs_put_subrequest(struct netfs_read_subrequest *subreq)
 	trace_netfs_sreq(subreq, netfs_sreq_trace_free);
 	netfs_put_read_request(subreq->rreq);
 	kfree(subreq);
+	netfs_stat_d(&netfs_n_rh_sreq);
 }
 
 /*
@@ -150,6 +154,7 @@ static void netfs_clear_unread(struct netfs_read_subrequest *subreq)
 static void netfs_fill_with_zeroes(struct netfs_read_request *rreq,
 				   struct netfs_read_subrequest *subreq)
 {
+	netfs_stat(&netfs_n_rh_zero);
 	__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
 	netfs_subreq_terminated(subreq, 0);
 }
@@ -173,6 +178,7 @@ static void netfs_fill_with_zeroes(struct netfs_read_request *rreq,
 static void netfs_read_from_server(struct netfs_read_request *rreq,
 				   struct netfs_read_subrequest *subreq)
 {
+	netfs_stat(&netfs_n_rh_download);
 	rreq->netfs_ops->issue_op(subreq);
 }
 
@@ -278,6 +284,7 @@ static void netfs_rreq_short_read(struct netfs_read_request *rreq,
 	__clear_bit(NETFS_SREQ_SHORT_READ, &subreq->flags);
 	__set_bit(NETFS_SREQ_SEEK_DATA_READ, &subreq->flags);
 
+	netfs_stat(&netfs_n_rh_short_read);
 	trace_netfs_sreq(subreq, netfs_sreq_trace_resubmit_short);
 
 	netfs_get_read_subrequest(subreq);
@@ -309,6 +316,7 @@ static bool netfs_rreq_perform_resubmissions(struct netfs_read_request *rreq)
 				break;
 			subreq->source = NETFS_DOWNLOAD_FROM_SERVER;
 			subreq->error = 0;
+			netfs_stat(&netfs_n_rh_download_instead);
 			trace_netfs_sreq(subreq, netfs_sreq_trace_download_instead);
 			netfs_get_read_subrequest(subreq);
 			atomic_inc(&rreq->nr_rd_ops);
@@ -399,6 +407,17 @@ void netfs_subreq_terminated(struct netfs_read_subrequest *subreq,
 	       subreq->debug_index, subreq->start, subreq->flags,
 	       transferred_or_error);
 
+	switch (subreq->source) {
+	case NETFS_READ_FROM_CACHE:
+		netfs_stat(&netfs_n_rh_read_done);
+		break;
+	case NETFS_DOWNLOAD_FROM_SERVER:
+		netfs_stat(&netfs_n_rh_download_done);
+		break;
+	default:
+		break;
+	}
+
 	if (IS_ERR_VALUE(transferred_or_error)) {
 		subreq->error = transferred_or_error;
 		goto failed;
@@ -452,8 +471,10 @@ void netfs_subreq_terminated(struct netfs_read_subrequest *subreq,
 
 failed:
 	if (subreq->source == NETFS_READ_FROM_CACHE) {
+		netfs_stat(&netfs_n_rh_read_failed);
 		set_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags);
 	} else {
+		netfs_stat(&netfs_n_rh_download_failed);
 		set_bit(NETFS_RREQ_FAILED, &rreq->flags);
 		rreq->error = subreq->error;
 	}
@@ -636,6 +657,7 @@ void netfs_readahead(struct readahead_control *ractl,
 	rreq->start	= readahead_pos(ractl);
 	rreq->len	= readahead_length(ractl);
 
+	netfs_stat(&netfs_n_rh_readahead);
 	trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
 			 netfs_read_trace_readahead);
 
@@ -710,6 +732,7 @@ int netfs_readpage(struct file *file,
 	rreq->start	= page->index * PAGE_SIZE;
 	rreq->len	= thp_size(page);
 
+	netfs_stat(&netfs_n_rh_readpage);
 	trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_readpage);
 
 	netfs_get_read_request(rreq);
diff --git a/fs/netfs/stats.c b/fs/netfs/stats.c
new file mode 100644
index 000000000000..df6ff5718f25
--- /dev/null
+++ b/fs/netfs/stats.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Netfs support statistics
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/export.h>
+#include <linux/seq_file.h>
+#include <linux/netfs.h>
+#include "internal.h"
+
+atomic_t netfs_n_rh_readahead;
+atomic_t netfs_n_rh_readpage;
+atomic_t netfs_n_rh_rreq;
+atomic_t netfs_n_rh_sreq;
+atomic_t netfs_n_rh_download;
+atomic_t netfs_n_rh_download_done;
+atomic_t netfs_n_rh_download_failed;
+atomic_t netfs_n_rh_download_instead;
+atomic_t netfs_n_rh_read;
+atomic_t netfs_n_rh_read_done;
+atomic_t netfs_n_rh_read_failed;
+atomic_t netfs_n_rh_zero;
+atomic_t netfs_n_rh_short_read;
+atomic_t netfs_n_rh_write;
+atomic_t netfs_n_rh_write_done;
+atomic_t netfs_n_rh_write_failed;
+
+void netfs_stats_show(struct seq_file *m)
+{
+	seq_printf(m, "RdHelp : RA=%u RP=%u rr=%u sr=%u\n",
+		   atomic_read(&netfs_n_rh_readahead),
+		   atomic_read(&netfs_n_rh_readpage),
+		   atomic_read(&netfs_n_rh_rreq),
+		   atomic_read(&netfs_n_rh_sreq));
+	seq_printf(m, "RdHelp : ZR=%u sh=%u\n",
+		   atomic_read(&netfs_n_rh_zero),
+		   atomic_read(&netfs_n_rh_short_read));
+	seq_printf(m, "RdHelp : DL=%u ds=%u df=%u di=%u\n",
+		   atomic_read(&netfs_n_rh_download),
+		   atomic_read(&netfs_n_rh_download_done),
+		   atomic_read(&netfs_n_rh_download_failed),
+		   atomic_read(&netfs_n_rh_download_instead));
+	seq_printf(m, "RdHelp : RD=%u rs=%u rf=%u\n",
+		   atomic_read(&netfs_n_rh_read),
+		   atomic_read(&netfs_n_rh_read_done),
+		   atomic_read(&netfs_n_rh_read_failed));
+	seq_printf(m, "RdHelp : WR=%u ws=%u wf=%u\n",
+		   atomic_read(&netfs_n_rh_write),
+		   atomic_read(&netfs_n_rh_write_done),
+		   atomic_read(&netfs_n_rh_write_failed));
+}
+EXPORT_SYMBOL(netfs_stats_show);
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 0779cf082101..92a08d8b8e61 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -106,5 +106,6 @@ extern int netfs_readpage(struct file *,
 			  void *);
 
 extern void netfs_subreq_terminated(struct netfs_read_subrequest *, ssize_t);
+extern void netfs_stats_show(struct seq_file *);
 
 #endif /* _LINUX_NETFS_H */



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 09/32] netfs: Add write_begin helper
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (7 preceding siblings ...)
  2021-01-25 21:32 ` [PATCH 08/32] netfs: Gather stats David Howells
@ 2021-01-25 21:32 ` David Howells
  2021-01-25 21:32 ` [PATCH 10/32] netfs: Define an interface to talk to a cache David Howells
                   ` (22 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:32 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Add a helper to do the pre-reading work for the netfs write_begin address
space op.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/netfs/internal.h          |    2 +
 fs/netfs/read_helper.c       |  165 ++++++++++++++++++++++++++++++++++++++++++
 fs/netfs/stats.c             |   10 ++-
 include/linux/netfs.h        |    8 ++
 include/trace/events/netfs.h |    4 +
 5 files changed, 185 insertions(+), 4 deletions(-)

diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h
index 98b6f4516da1..b7f2c4459f33 100644
--- a/fs/netfs/internal.h
+++ b/fs/netfs/internal.h
@@ -34,8 +34,10 @@ extern atomic_t netfs_n_rh_read_failed;
 extern atomic_t netfs_n_rh_zero;
 extern atomic_t netfs_n_rh_short_read;
 extern atomic_t netfs_n_rh_write;
+extern atomic_t netfs_n_rh_write_begin;
 extern atomic_t netfs_n_rh_write_done;
 extern atomic_t netfs_n_rh_write_failed;
+extern atomic_t netfs_n_rh_write_zskip;
 
 
 static inline void netfs_stat(atomic_t *stat)
diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
index 275ac37e2834..eb34c368617d 100644
--- a/fs/netfs/read_helper.c
+++ b/fs/netfs/read_helper.c
@@ -760,3 +760,168 @@ int netfs_readpage(struct file *file,
 	return ret;
 }
 EXPORT_SYMBOL(netfs_readpage);
+
+static void netfs_clear_thp(struct page *page)
+{
+	unsigned int i;
+
+	for (i = 0; i < thp_nr_pages(page); i++)
+		clear_highpage(page + i);
+}
+
+/**
+ * netfs_write_begin - Helper to prepare for writing
+ * @file: The file to read from
+ * @mapping: The mapping to read from
+ * @pos: File position at which the write will begin
+ * @len: The length of the write in this page
+ * @flags: AOP_* flags
+ * @_page: Where to put the resultant page
+ * @_fsdata: Place for the netfs to store a cookie
+ * @ops: The network filesystem's operations for the helper to use
+ * @netfs_priv: Private netfs data to be retained in the request
+ *
+ * Pre-read data for a write-begin request by drawing data from the cache if
+ * possible, or the netfs if not.  Space beyond the EOF is zero-filled.
+ * Multiple I/O requests from different sources will get munged together.  If
+ * necessary, the readahead window can be expanded in either direction to a
+ * more convenient alighment for RPC efficiency or to make storage in the cache
+ * feasible.
+ *
+ * The calling netfs must provide a table of operations, only one of which,
+ * issue_op, is mandatory.
+ *
+ * The check_write_begin() operation can be provided to check for and flush
+ * conflicting writes once the page is grabbed and locked.  It is passed a
+ * pointer to the fsdata cookie that gets returned to the VM to be passed to
+ * write_end.  It is permitted to sleep.  It should return 0 if the request
+ * should go ahead; unlock the page and return -EAGAIN to cause the page to be
+ * regot; or return an error.
+ *
+ * This is usable whether or not caching is enabled.
+ */
+int netfs_write_begin(struct file *file, struct address_space *mapping,
+		      loff_t pos, unsigned int len, unsigned int flags,
+		      struct page **_page, void **_fsdata,
+		      const struct netfs_read_request_ops *ops,
+		      void *netfs_priv)
+{
+	struct netfs_read_request *rreq;
+	struct page *page, *xpage;
+	struct inode *inode = file_inode(file);
+	unsigned int debug_index = 0;
+	pgoff_t index = pos >> PAGE_SHIFT;
+	int pos_in_page = pos & ~PAGE_MASK;
+	loff_t size;
+	int ret;
+
+	struct readahead_control ractl = {
+		.file		= file,
+		.mapping	= mapping,
+		._index		= index,
+		._nr_pages	= 0,
+	};
+
+retry:
+	page = grab_cache_page_write_begin(mapping, index, 0);
+	if (!page)
+		return -ENOMEM;
+
+	if (ops->check_write_begin) {
+		/* Allow the netfs (eg. ceph) to flush conflicts. */
+		ret = ops->check_write_begin(file, pos, len, page, _fsdata);
+		if (ret < 0) {
+			if (ret == -EAGAIN)
+				goto retry;
+			goto error;
+		}
+	}
+
+	if (PageUptodate(page))
+		goto have_page;
+
+	/* If the page is beyond the EOF, we want to clear it - unless it's
+	 * within the cache granule containing the EOF, in which case we need
+	 * to preload the granule.
+	 */
+	size = i_size_read(inode);
+	if (!ops->is_cache_enabled(inode) &&
+	    ((pos_in_page == 0 && len == thp_size(page)) ||
+	     (pos >= size) ||
+	     (pos_in_page == 0 && (pos + len) >= size))) {
+		netfs_clear_thp(page);
+		SetPageUptodate(page);
+		netfs_stat(&netfs_n_rh_write_zskip);
+		goto have_page_no_wait;
+	}
+
+	ret = -ENOMEM;
+	rreq = netfs_alloc_read_request(ops, netfs_priv, file);
+	if (!rreq)
+		goto error;
+	rreq->mapping		= page->mapping;
+	rreq->start		= page->index * PAGE_SIZE;
+	rreq->len		= thp_size(page);
+	rreq->no_unlock_page	= page->index;
+	__set_bit(NETFS_RREQ_NO_UNLOCK_PAGE, &rreq->flags);
+	netfs_priv = NULL;
+
+	netfs_stat(&netfs_n_rh_write_begin);
+	trace_netfs_read(rreq, pos, len, netfs_read_trace_write_begin);
+
+	/* Expand the request to meet caching requirements and download
+	 * preferences.
+	 */
+	ractl._nr_pages = thp_nr_pages(page);
+	netfs_rreq_expand(rreq, &ractl);
+	netfs_get_read_request(rreq);
+
+	/* We hold the page locks, so we can drop the references */
+	while ((xpage = readahead_page(&ractl)))
+		if (xpage != page)
+			put_page(xpage);
+
+	atomic_set(&rreq->nr_rd_ops, 1);
+	do {
+		if (!netfs_rreq_submit_slice(rreq, &debug_index))
+			break;
+
+	} while (rreq->submitted < rreq->len);
+
+	// TODO: If we didn't submit enough readage, we need to clean up
+
+	/* Keep nr_rd_ops incremented so that the ref always belongs to us, and
+	 * the service code isn't punted off to a random thread pool to
+	 * process.
+	 */
+	for (;;) {
+		wait_var_event(&rreq->nr_rd_ops, atomic_read(&rreq->nr_rd_ops) == 1);
+		netfs_rreq_assess(rreq);
+		if (!test_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags))
+			break;
+		cond_resched();
+	}
+
+	ret = rreq->error;
+	netfs_put_read_request(rreq);
+	if (ret < 0)
+		goto error;
+
+have_page:
+	wait_on_page_fscache(page);
+have_page_no_wait:
+	if (netfs_priv)
+		ops->cleanup(netfs_priv, mapping);
+	*_page = page;
+	_leave(" = 0");
+	return 0;
+
+error:
+	unlock_page(page);
+	put_page(page);
+	if (netfs_priv)
+		ops->cleanup(netfs_priv, mapping);
+	_leave(" = %d", ret);
+	return ret;
+}
+EXPORT_SYMBOL(netfs_write_begin);
diff --git a/fs/netfs/stats.c b/fs/netfs/stats.c
index df6ff5718f25..dd7ad66ed07e 100644
--- a/fs/netfs/stats.c
+++ b/fs/netfs/stats.c
@@ -24,19 +24,23 @@ atomic_t netfs_n_rh_read_failed;
 atomic_t netfs_n_rh_zero;
 atomic_t netfs_n_rh_short_read;
 atomic_t netfs_n_rh_write;
+atomic_t netfs_n_rh_write_begin;
 atomic_t netfs_n_rh_write_done;
 atomic_t netfs_n_rh_write_failed;
+atomic_t netfs_n_rh_write_zskip;
 
 void netfs_stats_show(struct seq_file *m)
 {
-	seq_printf(m, "RdHelp : RA=%u RP=%u rr=%u sr=%u\n",
+	seq_printf(m, "RdHelp : RA=%u RP=%u WB=%u rr=%u sr=%u\n",
 		   atomic_read(&netfs_n_rh_readahead),
 		   atomic_read(&netfs_n_rh_readpage),
+		   atomic_read(&netfs_n_rh_write_begin),
 		   atomic_read(&netfs_n_rh_rreq),
 		   atomic_read(&netfs_n_rh_sreq));
-	seq_printf(m, "RdHelp : ZR=%u sh=%u\n",
+	seq_printf(m, "RdHelp : ZR=%u sh=%u sk=%u\n",
 		   atomic_read(&netfs_n_rh_zero),
-		   atomic_read(&netfs_n_rh_short_read));
+		   atomic_read(&netfs_n_rh_short_read),
+		   atomic_read(&netfs_n_rh_write_zskip));
 	seq_printf(m, "RdHelp : DL=%u ds=%u df=%u di=%u\n",
 		   atomic_read(&netfs_n_rh_download),
 		   atomic_read(&netfs_n_rh_download_done),
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 92a08d8b8e61..5b54f6637c22 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -87,11 +87,14 @@ struct netfs_read_request {
  * Operations the network filesystem can/must provide to the helpers.
  */
 struct netfs_read_request_ops {
+	bool (*is_cache_enabled)(struct inode *inode);
 	void (*init_rreq)(struct netfs_read_request *rreq, struct file *file);
 	void (*expand_readahead)(struct netfs_read_request *rreq);
 	bool (*clamp_length)(struct netfs_read_subrequest *subreq);
 	void (*issue_op)(struct netfs_read_subrequest *subreq);
 	bool (*is_still_valid)(struct netfs_read_request *rreq);
+	int (*check_write_begin)(struct file *file, loff_t pos, unsigned len,
+				 struct page *page, void **_fsdata);
 	void (*done)(struct netfs_read_request *rreq);
 	void (*cleanup)(struct address_space *mapping, void *netfs_priv);
 };
@@ -104,6 +107,11 @@ extern int netfs_readpage(struct file *,
 			  struct page *,
 			  const struct netfs_read_request_ops *,
 			  void *);
+extern int netfs_write_begin(struct file *, struct address_space *,
+			     loff_t, unsigned int, unsigned int, struct page **,
+			     void **,
+			     const struct netfs_read_request_ops *,
+			     void *);
 
 extern void netfs_subreq_terminated(struct netfs_read_subrequest *, ssize_t);
 extern void netfs_stats_show(struct seq_file *);
diff --git a/include/trace/events/netfs.h b/include/trace/events/netfs.h
index 12ad382764c5..a2bf6cd84bd4 100644
--- a/include/trace/events/netfs.h
+++ b/include/trace/events/netfs.h
@@ -22,6 +22,7 @@ enum netfs_read_trace {
 	netfs_read_trace_expanded,
 	netfs_read_trace_readahead,
 	netfs_read_trace_readpage,
+	netfs_read_trace_write_begin,
 };
 
 enum netfs_rreq_trace {
@@ -50,7 +51,8 @@ enum netfs_sreq_trace {
 #define netfs_read_traces					\
 	EM(netfs_read_trace_expanded,		"EXPANDED ")	\
 	EM(netfs_read_trace_readahead,		"READAHEAD")	\
-	E_(netfs_read_trace_readpage,		"READPAGE ")
+	EM(netfs_read_trace_readpage,		"READPAGE ")	\
+	E_(netfs_read_trace_write_begin,	"WRITEBEGN")
 
 #define netfs_rreq_traces					\
 	EM(netfs_rreq_trace_assess,		"ASSESS")	\



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 10/32] netfs: Define an interface to talk to a cache
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (8 preceding siblings ...)
  2021-01-25 21:32 ` [PATCH 09/32] netfs: Add write_begin helper David Howells
@ 2021-01-25 21:32 ` David Howells
  2021-01-25 21:32 ` [PATCH 11/32] fscache, cachefiles: Add alternate API to use kiocb for read/write to cache David Howells
                   ` (21 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:32 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Add an interface to the netfs helper library for reading data from the
cache instead of downloading it from the server and support for writing
data just downloaded or cleared to the cache.

The API passes an iov_iter to the cache read/write routines to indicate the
data/buffer to be used.  This is done using the ITER_XARRAY type to provide
direct access to the netfs inode's pagecache.

When the netfs's ->begin_cache_operation() method is called, this must fill
in the cache_resources in the netfs_read_request struct, including the
netfs_cache_ops used by the helper lib to talk to the cache.  The helper
lib does not directly access the cache.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/netfs/read_helper.c        |  230 +++++++++++++++++++++++++++++++++++++++++
 fs/netfs/stats.c              |    3 -
 include/linux/fscache-cache.h |    4 +
 include/linux/fscache.h       |   17 +++
 include/linux/netfs.h         |   48 +++++++++
 5 files changed, 300 insertions(+), 2 deletions(-)

diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
index eb34c368617d..d06befe5354a 100644
--- a/fs/netfs/read_helper.c
+++ b/fs/netfs/read_helper.c
@@ -86,6 +86,8 @@ static void netfs_free_read_request(struct work_struct *work)
 	if (rreq->netfs_priv)
 		rreq->netfs_ops->cleanup(rreq->mapping, rreq->netfs_priv);
 	trace_netfs_rreq(rreq, netfs_rreq_trace_free);
+	if (rreq->cache_resources.ops)
+		rreq->cache_resources.ops->end_operation(&rreq->cache_resources);
 	kfree(rreq);
 	netfs_stat_d(&netfs_n_rh_rreq);
 }
@@ -148,6 +150,32 @@ static void netfs_clear_unread(struct netfs_read_subrequest *subreq)
 	iov_iter_zero(iov_iter_count(&iter), &iter);
 }
 
+static void netfs_cache_read_terminated(void *priv, ssize_t transferred_or_error)
+{
+	struct netfs_read_subrequest *subreq = priv;
+
+	netfs_subreq_terminated(subreq, transferred_or_error);
+}
+
+/*
+ * Issue a read against the cache.
+ * - Eats the caller's ref on subreq.
+ */
+static void netfs_read_from_cache(struct netfs_read_request *rreq,
+				  struct netfs_read_subrequest *subreq,
+				  bool seek_data)
+{
+	struct netfs_cache_resources *cres = &rreq->cache_resources;
+	struct iov_iter iter;
+
+	iov_iter_xarray(&iter, READ, &rreq->mapping->i_pages,
+			subreq->start + subreq->transferred,
+			subreq->len   - subreq->transferred);
+
+	cres->ops->read(cres, subreq->start, &iter, seek_data,
+			netfs_cache_read_terminated, subreq);
+}
+
 /*
  * Fill a subrequest region with zeroes.
  */
@@ -192,6 +220,141 @@ static void netfs_rreq_completed(struct netfs_read_request *rreq)
 	netfs_put_read_request(rreq);
 }
 
+/*
+ * Deal with the completion of writing the data to the cache.  We have to clear
+ * the PG_fscache bits on the pages involved and release the caller's ref.
+ *
+ * May be called in softirq mode and we inherit a ref from the caller.
+ */
+static void netfs_rreq_unmark_after_write(struct netfs_read_request *rreq)
+{
+	struct netfs_read_subrequest *subreq;
+	struct page *page;
+	pgoff_t unlocked = 0;
+	bool have_unlocked = false;
+
+	rcu_read_lock();
+
+	list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
+		XA_STATE(xas, &rreq->mapping->i_pages, subreq->start / PAGE_SIZE);
+
+		xas_for_each(&xas, page, (subreq->start + subreq->len - 1) / PAGE_SIZE) {
+			/* We might have multiple writes from the same huge
+			 * page, but we mustn't unlock a page more than once.
+			 */
+			if (have_unlocked && page->index <= unlocked)
+				continue;
+			unlocked = page->index;
+			unlock_page_fscache(page);
+			have_unlocked = true;
+		}
+	}
+
+	rcu_read_unlock();
+	netfs_rreq_completed(rreq);
+}
+
+static void netfs_rreq_copy_terminated(void *priv, ssize_t transferred_or_error)
+{
+	struct netfs_read_subrequest *subreq = priv;
+	struct netfs_read_request *rreq = subreq->rreq;
+
+	if (IS_ERR_VALUE(transferred_or_error)) {
+		subreq->error = transferred_or_error;
+		netfs_stat(&netfs_n_rh_write_failed);
+	} else {
+		subreq->error = 0;
+		netfs_stat(&netfs_n_rh_write_done);
+	}
+
+	trace_netfs_sreq(subreq, netfs_sreq_trace_write_term);
+
+	/* If we decrement nr_wr_ops to 0, the ref belongs to us. */
+	if (atomic_dec_and_test(&rreq->nr_wr_ops))
+		netfs_rreq_unmark_after_write(rreq);
+
+	netfs_put_subrequest(subreq);
+}
+
+/*
+ * Perform any outstanding writes to the cache.  We inherit a ref from the
+ * caller.
+ */
+static void netfs_rreq_do_write_to_cache(struct netfs_read_request *rreq)
+{
+	struct netfs_cache_resources *cres = &rreq->cache_resources;
+	struct netfs_read_subrequest *subreq, *next, *p;
+	struct iov_iter iter;
+	loff_t pos;
+
+	trace_netfs_rreq(rreq, netfs_rreq_trace_write);
+
+	/* We don't want terminating writes trying to wake us up whilst we're
+	 * still going through the list.
+	 */
+	atomic_inc(&rreq->nr_wr_ops);
+
+	list_for_each_entry_safe(subreq, p, &rreq->subrequests, rreq_link) {
+		if (!test_bit(NETFS_SREQ_WRITE_TO_CACHE, &subreq->flags)) {
+			list_del_init(&subreq->rreq_link);
+			netfs_put_subrequest(subreq);
+		}
+	}
+
+	list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
+		/* Amalgamate adjacent writes */
+		pos = round_down(subreq->start, PAGE_SIZE);
+		if (pos != subreq->start) {
+			subreq->len += subreq->start - pos;
+			subreq->start = pos;
+		}
+		subreq->len = round_up(subreq->len, PAGE_SIZE);
+
+		while (!list_is_last(&subreq->rreq_link, &rreq->subrequests)) {
+			next = list_next_entry(subreq, rreq_link);
+			if (next->start > subreq->start + subreq->len)
+				break;
+			subreq->len += next->len;
+			subreq->len = round_up(subreq->len, PAGE_SIZE);
+			list_del_init(&next->rreq_link);
+			netfs_put_subrequest(next);
+		}
+
+		iov_iter_xarray(&iter, WRITE, &rreq->mapping->i_pages,
+				subreq->start, subreq->len);
+
+		atomic_inc(&rreq->nr_wr_ops);
+		netfs_stat(&netfs_n_rh_write);
+		netfs_get_read_subrequest(subreq);
+		trace_netfs_sreq(subreq, netfs_sreq_trace_write);
+		cres->ops->write(cres, subreq->start, &iter,
+				 netfs_rreq_copy_terminated, subreq);
+	}
+
+	/* If we decrement nr_wr_ops to 0, the usage ref belongs to us. */
+	if (atomic_dec_and_test(&rreq->nr_wr_ops))
+		netfs_rreq_unmark_after_write(rreq);
+}
+
+static void netfs_rreq_write_to_cache_work(struct work_struct *work)
+{
+	struct netfs_read_request *rreq =
+		container_of(work, struct netfs_read_request, work);
+
+	netfs_rreq_do_write_to_cache(rreq);
+}
+
+static void netfs_rreq_write_to_cache(struct netfs_read_request *rreq)
+{
+	if (in_softirq()) {
+		rreq->work.func = netfs_rreq_write_to_cache_work;
+		if (!queue_work(system_unbound_wq, &rreq->work))
+			BUG();
+	} else {
+		netfs_rreq_do_write_to_cache(rreq);
+	}
+}
+
 /*
  * Unlock the pages in a read operation.  We need to set PG_fscache on any
  * pages we're going to write back before we unlock them.
@@ -289,7 +452,10 @@ static void netfs_rreq_short_read(struct netfs_read_request *rreq,
 
 	netfs_get_read_subrequest(subreq);
 	atomic_inc(&rreq->nr_rd_ops);
-	netfs_read_from_server(rreq, subreq);
+	if (subreq->source == NETFS_READ_FROM_CACHE)
+		netfs_read_from_cache(rreq, subreq, true);
+	else
+		netfs_read_from_server(rreq, subreq);
 }
 
 /*
@@ -334,6 +500,25 @@ static bool netfs_rreq_perform_resubmissions(struct netfs_read_request *rreq)
 	return false;
 }
 
+/*
+ * Check to see if the data read is still valid.
+ */
+static void netfs_rreq_is_still_valid(struct netfs_read_request *rreq)
+{
+	struct netfs_read_subrequest *subreq;
+
+	if (!rreq->netfs_ops->is_still_valid ||
+	    rreq->netfs_ops->is_still_valid(rreq))
+		return;
+
+	list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
+		if (subreq->source == NETFS_READ_FROM_CACHE) {
+			subreq->error = -ESTALE;
+			__set_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags);
+		}
+	}
+}
+
 /*
  * Assess the state of a read request and decide what to do next.
  *
@@ -345,6 +530,8 @@ static void netfs_rreq_assess(struct netfs_read_request *rreq)
 	trace_netfs_rreq(rreq, netfs_rreq_trace_assess);
 
 again:
+	netfs_rreq_is_still_valid(rreq);
+
 	if (!test_bit(NETFS_RREQ_FAILED, &rreq->flags) &&
 	    test_bit(NETFS_RREQ_INCOMPLETE_IO, &rreq->flags)) {
 		if (netfs_rreq_perform_resubmissions(rreq))
@@ -357,6 +544,9 @@ static void netfs_rreq_assess(struct netfs_read_request *rreq)
 	clear_bit_unlock(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
 	wake_up_bit(&rreq->flags, NETFS_RREQ_IN_PROGRESS);
 
+	if (test_bit(NETFS_RREQ_WRITE_TO_CACHE, &rreq->flags))
+		return netfs_rreq_write_to_cache(rreq);
+
 	netfs_rreq_completed(rreq);
 }
 
@@ -486,7 +676,10 @@ static enum netfs_read_source netfs_cache_prepare_read(struct netfs_read_subrequ
 						       loff_t i_size)
 {
 	struct netfs_read_request *rreq = subreq->rreq;
+	struct netfs_cache_resources *cres = &rreq->cache_resources;
 
+	if (cres->ops)
+		return cres->ops->prepare_read(subreq, i_size);
 	if (subreq->start >= rreq->i_size)
 		return NETFS_FILL_WITH_ZEROES;
 	return NETFS_DOWNLOAD_FROM_SERVER;
@@ -578,6 +771,9 @@ static bool netfs_rreq_submit_slice(struct netfs_read_request *rreq,
 	case NETFS_DOWNLOAD_FROM_SERVER:
 		netfs_read_from_server(rreq, subreq);
 		break;
+	case NETFS_READ_FROM_CACHE:
+		netfs_read_from_cache(rreq, subreq, false);
+		break;
 	default:
 		BUG();
 	}
@@ -590,9 +786,23 @@ static bool netfs_rreq_submit_slice(struct netfs_read_request *rreq,
 	return false;
 }
 
+static void netfs_cache_expand_readahead(struct netfs_read_request *rreq,
+					 loff_t *_start, size_t *_len, loff_t i_size)
+{
+	struct netfs_cache_resources *cres = &rreq->cache_resources;
+
+	if (cres->ops && cres->ops->expand_readahead)
+		cres->ops->expand_readahead(cres, _start, _len, i_size);
+}
+
 static void netfs_rreq_expand(struct netfs_read_request *rreq,
 			      struct readahead_control *ractl)
 {
+	/* Give the cache a chance to change the request parameters.  The
+	 * resultant request must contain the original region.
+	 */
+	netfs_cache_expand_readahead(rreq, &rreq->start, &rreq->len, rreq->i_size);
+
 	/* Give the netfs a chance to change the request parameters.  The
 	 * resultant request must contain the original region.
 	 */
@@ -644,6 +854,7 @@ void netfs_readahead(struct readahead_control *ractl,
 	struct netfs_read_request *rreq;
 	struct page *page;
 	unsigned int debug_index = 0;
+	int ret;
 
 	_enter("%lx,%x", readahead_index(ractl), readahead_count(ractl));
 
@@ -661,6 +872,11 @@ void netfs_readahead(struct readahead_control *ractl,
 	trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
 			 netfs_read_trace_readahead);
 
+	if (ops->begin_cache_operation) {
+		ret = ops->begin_cache_operation(rreq);
+		if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
+			goto cleanup_free;
+	}
 	netfs_rreq_expand(rreq, ractl);
 
 	atomic_set(&rreq->nr_rd_ops, 1);
@@ -686,6 +902,9 @@ void netfs_readahead(struct readahead_control *ractl,
 		netfs_rreq_assess(rreq);
 	return;
 
+cleanup_free:
+	netfs_put_read_request(rreq);
+	return;
 cleanup:
 	if (netfs_priv)
 		ops->cleanup(ractl->mapping, netfs_priv);
@@ -735,6 +954,14 @@ int netfs_readpage(struct file *file,
 	netfs_stat(&netfs_n_rh_readpage);
 	trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_readpage);
 
+	if (ops->begin_cache_operation) {
+		ret = ops->begin_cache_operation(rreq);
+		if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS) {
+			unlock_page(page);
+			goto out;
+		}
+	}
+
 	netfs_get_read_request(rreq);
 
 	atomic_set(&rreq->nr_rd_ops, 1);
@@ -756,6 +983,7 @@ int netfs_readpage(struct file *file,
 	} while (test_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags));
 
 	ret = rreq->error;
+out:
 	netfs_put_read_request(rreq);
 	return ret;
 }
diff --git a/fs/netfs/stats.c b/fs/netfs/stats.c
index dd7ad66ed07e..9ae538c85378 100644
--- a/fs/netfs/stats.c
+++ b/fs/netfs/stats.c
@@ -31,10 +31,11 @@ atomic_t netfs_n_rh_write_zskip;
 
 void netfs_stats_show(struct seq_file *m)
 {
-	seq_printf(m, "RdHelp : RA=%u RP=%u WB=%u rr=%u sr=%u\n",
+	seq_printf(m, "RdHelp : RA=%u RP=%u WB=%u WBZ=%u rr=%u sr=%u\n",
 		   atomic_read(&netfs_n_rh_readahead),
 		   atomic_read(&netfs_n_rh_readpage),
 		   atomic_read(&netfs_n_rh_write_begin),
+		   atomic_read(&netfs_n_rh_write_zskip),
 		   atomic_read(&netfs_n_rh_rreq),
 		   atomic_read(&netfs_n_rh_sreq));
 	seq_printf(m, "RdHelp : ZR=%u sh=%u sk=%u\n",
diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index 3f0b19dcfae7..3235ddbdcc09 100644
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -304,6 +304,10 @@ struct fscache_cache_ops {
 
 	/* dissociate a cache from all the pages it was backing */
 	void (*dissociate_pages)(struct fscache_cache *cache);
+
+	/* Begin a read operation for the netfs lib */
+	int (*begin_read_operation)(struct netfs_read_request *rreq,
+				    struct fscache_retrieval *op);
 };
 
 extern struct fscache_cookie fscache_fsdef_index;
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index 1f8dc72369ee..0e4161ce347c 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -37,6 +37,7 @@ struct pagevec;
 struct fscache_cache_tag;
 struct fscache_cookie;
 struct fscache_netfs;
+struct netfs_read_request;
 
 typedef void (*fscache_rw_complete_t)(struct page *page,
 				      void *context,
@@ -217,6 +218,7 @@ extern void __fscache_readpages_cancel(struct fscache_cookie *cookie,
 extern void __fscache_disable_cookie(struct fscache_cookie *, const void *, bool);
 extern void __fscache_enable_cookie(struct fscache_cookie *, const void *, loff_t,
 				    bool (*)(void *), void *);
+extern int __fscache_begin_read_operation(struct netfs_read_request *, struct fscache_cookie *);
 
 /**
  * fscache_register_netfs - Register a filesystem as desiring caching services
@@ -831,4 +833,19 @@ void fscache_enable_cookie(struct fscache_cookie *cookie,
 					can_enable, data);
 }
 
+/**
+ * fscache_begin_read_operation - Begin a read operation for the netfs lib
+ * @rreq: The read request being undertaken
+ * @cookie: The cookie representing the cache object
+ */
+static inline
+int fscache_begin_read_operation(struct netfs_read_request *rreq,
+				 struct fscache_cookie *cookie)
+{
+	if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
+		return __fscache_begin_read_operation(rreq, cookie);
+	else
+		return -ENOBUFS;
+}
+
 #endif /* _LINUX_FSCACHE_H */
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 5b54f6637c22..2ffdef1ded91 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -32,6 +32,17 @@ enum netfs_read_source {
 	NETFS_INVALID_READ,
 } __mode(byte);
 
+typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error);
+
+/*
+ * Resources required to do operations on a cache.
+ */
+struct netfs_cache_resources {
+	const struct netfs_cache_ops	*ops;
+	void				*cache_priv;
+	void				*cache_priv2;
+};
+
 /*
  * Descriptor for a single component subrequest.
  */
@@ -61,11 +72,13 @@ struct netfs_read_request {
 	struct work_struct	work;
 	struct inode		*inode;		/* The file being accessed */
 	struct address_space	*mapping;	/* The mapping being accessed */
+	struct netfs_cache_resources cache_resources;
 	struct list_head	subrequests;	/* Requests to fetch I/O from disk or net */
 	void			*netfs_priv;	/* Private data for the netfs */
 	unsigned int		debug_id;
 	unsigned int		cookie_debug_id;
 	atomic_t		nr_rd_ops;	/* Number of read ops in progress */
+	atomic_t		nr_wr_ops;	/* Number of write ops in progress */
 	size_t			submitted;	/* Amount submitted for I/O so far */
 	size_t			len;		/* Length of the request */
 	short			error;		/* 0 or error that occurred */
@@ -89,6 +102,7 @@ struct netfs_read_request {
 struct netfs_read_request_ops {
 	bool (*is_cache_enabled)(struct inode *inode);
 	void (*init_rreq)(struct netfs_read_request *rreq, struct file *file);
+	int (*begin_cache_operation)(struct netfs_read_request *rreq);
 	void (*expand_readahead)(struct netfs_read_request *rreq);
 	bool (*clamp_length)(struct netfs_read_subrequest *subreq);
 	void (*issue_op)(struct netfs_read_subrequest *subreq);
@@ -99,6 +113,40 @@ struct netfs_read_request_ops {
 	void (*cleanup)(struct address_space *mapping, void *netfs_priv);
 };
 
+/*
+ * Table of operations for access to a cache.  This is obtained by
+ * rreq->ops->begin_cache_operation().
+ */
+struct netfs_cache_ops {
+	/* End an operation */
+	void (*end_operation)(struct netfs_cache_resources *cres);
+
+	/* Read data from the cache */
+	int (*read)(struct netfs_cache_resources *cres,
+		    loff_t start_pos,
+		    struct iov_iter *iter,
+		    bool seek_data,
+		    netfs_io_terminated_t term_func,
+		    void *term_func_priv);
+
+	/* Write data to the cache */
+	int (*write)(struct netfs_cache_resources *cres,
+		     loff_t start_pos,
+		     struct iov_iter *iter,
+		     netfs_io_terminated_t term_func,
+		     void *term_func_priv);
+
+	/* Expand readahead request */
+	void (*expand_readahead)(struct netfs_cache_resources *cres,
+				 loff_t *_start, size_t *_len, loff_t i_size);
+
+	/* Prepare a read operation, shortening it to a cached/uncached
+	 * boundary as appropriate.
+	 */
+	enum netfs_read_source (*prepare_read)(struct netfs_read_subrequest *subreq,
+					       loff_t i_size);
+};
+
 struct readahead_control;
 extern void netfs_readahead(struct readahead_control *,
 			    const struct netfs_read_request_ops *,



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 11/32] fscache, cachefiles: Add alternate API to use kiocb for read/write to cache
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (9 preceding siblings ...)
  2021-01-25 21:32 ` [PATCH 10/32] netfs: Define an interface to talk to a cache David Howells
@ 2021-01-25 21:32 ` David Howells
  2021-01-25 21:33 ` [PATCH 12/32] afs: Disable use of the fscache I/O routines David Howells
                   ` (20 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:32 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Add an alternate API by which the cache can be accessed through a kiocb,
doing async DIO, rather than using the current API that tells the cache
where all the pages are.

The new API is intended to be used in conjunction with the netfs helper
library.  A filesystem must pick one or the other and not mix them.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/cachefiles/Makefile    |    1 
 fs/cachefiles/interface.c |    5 -
 fs/cachefiles/internal.h  |    9 +
 fs/cachefiles/rdwr2.c     |  412 +++++++++++++++++++++++++++++++++++++++++++++
 fs/fscache/Kconfig        |    1 
 fs/fscache/Makefile       |    3 
 fs/fscache/internal.h     |    3 
 fs/fscache/page.c         |    2 
 fs/fscache/page2.c        |  116 +++++++++++++
 fs/fscache/stats.c        |    1 
 10 files changed, 549 insertions(+), 4 deletions(-)
 create mode 100644 fs/cachefiles/rdwr2.c
 create mode 100644 fs/fscache/page2.c

diff --git a/fs/cachefiles/Makefile b/fs/cachefiles/Makefile
index 891dedda5905..ea17b169ea5e 100644
--- a/fs/cachefiles/Makefile
+++ b/fs/cachefiles/Makefile
@@ -11,6 +11,7 @@ cachefiles-y := \
 	main.o \
 	namei.o \
 	rdwr.o \
+	rdwr2.o \
 	security.o \
 	xattr.o
 
diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
index 4cea5fbf695e..eaede2585d07 100644
--- a/fs/cachefiles/interface.c
+++ b/fs/cachefiles/interface.c
@@ -319,8 +319,8 @@ static void cachefiles_drop_object(struct fscache_object *_object)
 /*
  * dispose of a reference to an object
  */
-static void cachefiles_put_object(struct fscache_object *_object,
-				  enum fscache_obj_ref_trace why)
+void cachefiles_put_object(struct fscache_object *_object,
+			   enum fscache_obj_ref_trace why)
 {
 	struct cachefiles_object *object;
 	struct fscache_cache *cache;
@@ -568,4 +568,5 @@ const struct fscache_cache_ops cachefiles_cache_ops = {
 	.uncache_page		= cachefiles_uncache_page,
 	.dissociate_pages	= cachefiles_dissociate_pages,
 	.check_consistency	= cachefiles_check_consistency,
+	.begin_read_operation	= cachefiles_begin_read_operation,
 };
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index cf9bd6401c2d..896819b80bbc 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -150,6 +150,9 @@ extern int cachefiles_has_space(struct cachefiles_cache *cache,
  */
 extern const struct fscache_cache_ops cachefiles_cache_ops;
 
+extern void cachefiles_put_object(struct fscache_object *_object,
+				  enum fscache_obj_ref_trace why);
+
 /*
  * key.c
  */
@@ -217,6 +220,12 @@ extern int cachefiles_allocate_pages(struct fscache_retrieval *,
 extern int cachefiles_write_page(struct fscache_storage *, struct page *);
 extern void cachefiles_uncache_page(struct fscache_object *, struct page *);
 
+/*
+ * rdwr2.c
+ */
+extern int cachefiles_begin_read_operation(struct netfs_read_request *,
+					   struct fscache_retrieval *);
+
 /*
  * security.c
  */
diff --git a/fs/cachefiles/rdwr2.c b/fs/cachefiles/rdwr2.c
new file mode 100644
index 000000000000..4cea5a2a2d6e
--- /dev/null
+++ b/fs/cachefiles/rdwr2.c
@@ -0,0 +1,412 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* kiocb-using read/write
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/mount.h>
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/uio.h>
+#include <linux/sched/mm.h>
+#include <linux/netfs.h>
+#include "internal.h"
+
+struct cachefiles_kiocb {
+	struct kiocb		iocb;
+	refcount_t		ki_refcnt;
+	loff_t			start;
+	union {
+		size_t		skipped;
+		size_t		len;
+	};
+	netfs_io_terminated_t	term_func;
+	void			*term_func_priv;
+};
+
+static inline void cachefiles_put_kiocb(struct cachefiles_kiocb *ki)
+{
+	if (refcount_dec_and_test(&ki->ki_refcnt)) {
+		fput(ki->iocb.ki_filp);
+		kfree(ki);
+	}
+}
+
+/*
+ * Handle completion of a read from the cache.
+ */
+static void cachefiles_read_complete(struct kiocb *iocb, long ret, long ret2)
+{
+	struct cachefiles_kiocb *ki = container_of(iocb, struct cachefiles_kiocb, iocb);
+
+	_enter("%ld,%ld", ret, ret2);
+
+	if (ki->term_func) {
+		if (ret < 0)
+			ki->term_func(ki->term_func_priv, ret);
+		else
+			ki->term_func(ki->term_func_priv, ki->skipped + ret);
+	}
+
+	cachefiles_put_kiocb(ki);
+}
+
+/*
+ * Initiate a read from the cache.
+ */
+static int cachefiles_read(struct netfs_cache_resources *cres,
+			   loff_t start_pos,
+			   struct iov_iter *iter,
+			   bool seek_data,
+			   netfs_io_terminated_t term_func,
+			   void *term_func_priv)
+{
+	struct cachefiles_kiocb *ki;
+	struct file *file = cres->cache_priv2;
+	unsigned int old_nofs;
+	ssize_t ret = -ENOBUFS;
+	size_t len = iov_iter_count(iter), skipped = 0;
+
+	_enter("%pD,%li,%llx,%zx/%llx",
+	       file, file_inode(file)->i_ino, start_pos, len,
+	       i_size_read(file->f_inode));
+
+	/* If the caller asked us to seek for data before doing the read, then
+	 * we should do that now.  If we find a gap, we fill it with zeros.
+	 */
+	if (seek_data) {
+		loff_t off = start_pos, off2;
+
+		off2 = vfs_llseek(file, off, SEEK_DATA);
+		if (off2 < 0 && off2 >= (loff_t)-MAX_ERRNO && off2 != -ENXIO) {
+			skipped = 0;
+			ret = off2;
+			goto presubmission_error;
+		}
+
+		if (off2 == -ENXIO || off2 >= start_pos + len) {
+			/* The region is beyond the EOF or there's no more data
+			 * in the region, so clear the rest of the buffer and
+			 * return success.
+			 */
+			iov_iter_zero(len, iter);
+			skipped = len;
+			ret = 0;
+			goto presubmission_error;
+		}
+
+		skipped = off2 - off;
+		iov_iter_zero(skipped, iter);
+	}
+
+	ret = -ENOBUFS;
+	ki = kzalloc(sizeof(struct cachefiles_kiocb), GFP_KERNEL);
+	if (!ki)
+		goto presubmission_error;
+
+	refcount_set(&ki->ki_refcnt, 2);
+	ki->iocb.ki_filp	= file;
+	ki->iocb.ki_pos		= start_pos + skipped;
+	ki->iocb.ki_flags	= IOCB_DIRECT;
+	ki->iocb.ki_hint	= ki_hint_validate(file_write_hint(file));
+	ki->iocb.ki_ioprio	= get_current_ioprio();
+	ki->skipped		= skipped;
+	ki->term_func		= term_func;
+	ki->term_func_priv	= term_func_priv;
+
+	if (ki->term_func)
+		ki->iocb.ki_complete = cachefiles_read_complete;
+
+	ret = rw_verify_area(READ, file, &ki->iocb.ki_pos, len - skipped);
+	if (ret < 0)
+		goto presubmission_error_free;
+
+	get_file(ki->iocb.ki_filp);
+
+	old_nofs = memalloc_nofs_save();
+	ret = call_read_iter(file, &ki->iocb, iter);
+	memalloc_nofs_restore(old_nofs);
+	switch (ret) {
+	case -EIOCBQUEUED:
+		goto in_progress;
+
+	case -ERESTARTSYS:
+	case -ERESTARTNOINTR:
+	case -ERESTARTNOHAND:
+	case -ERESTART_RESTARTBLOCK:
+		/* There's no easy way to restart the syscall since other AIO's
+		 * may be already running. Just fail this IO with EINTR.
+		 */
+		ret = -EINTR;
+		fallthrough;
+	default:
+		cachefiles_read_complete(&ki->iocb, ret, 0);
+		if (ret > 0)
+			ret = 0;
+		break;
+	}
+
+in_progress:
+	cachefiles_put_kiocb(ki);
+	_leave(" = %zd", ret);
+	return ret;
+
+presubmission_error_free:
+	kfree(ki);
+presubmission_error:
+	if (term_func)
+		term_func(term_func_priv, ret < 0 ? ret : skipped);
+	return ret;
+}
+
+/*
+ * Handle completion of a write to the cache.
+ */
+static void cachefiles_write_complete(struct kiocb *iocb, long ret, long ret2)
+{
+	struct cachefiles_kiocb *ki = container_of(iocb, struct cachefiles_kiocb, iocb);
+	struct inode *inode = file_inode(ki->iocb.ki_filp);
+
+	_enter("%ld,%ld", ret, ret2);
+
+	/* Tell lockdep we inherited freeze protection from submission thread */
+	__sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
+	__sb_end_write(inode->i_sb, SB_FREEZE_WRITE);
+
+	if (ki->term_func)
+		ki->term_func(ki->term_func_priv, ret);
+
+	cachefiles_put_kiocb(ki);
+}
+
+/*
+ * Initiate a write to the cache.
+ */
+static int cachefiles_write(struct netfs_cache_resources *cres,
+			    loff_t start_pos,
+			    struct iov_iter *iter,
+			    netfs_io_terminated_t term_func,
+			    void *term_func_priv)
+{
+	struct cachefiles_kiocb *ki;
+	struct inode *inode;
+	struct file *file = cres->cache_priv2;
+	unsigned int old_nofs;
+	ssize_t ret = -ENOBUFS;
+	size_t len = iov_iter_count(iter);
+
+	_enter("%pD,%li,%llx,%zx/%llx",
+	       file, file_inode(file)->i_ino, start_pos, len,
+	       i_size_read(file->f_inode));
+
+	ki = kzalloc(sizeof(struct cachefiles_kiocb), GFP_KERNEL);
+	if (!ki)
+		goto presubmission_error;
+
+	refcount_set(&ki->ki_refcnt, 2);
+	ki->iocb.ki_filp	= file;
+	ki->iocb.ki_pos		= start_pos;
+	ki->iocb.ki_flags	= IOCB_DIRECT | IOCB_WRITE;
+	ki->iocb.ki_hint	= ki_hint_validate(file_write_hint(file));
+	ki->iocb.ki_ioprio	= get_current_ioprio();
+	ki->start		= start_pos;
+	ki->len			= len;
+	ki->term_func		= term_func;
+	ki->term_func_priv	= term_func_priv;
+
+	if (ki->term_func)
+		ki->iocb.ki_complete = cachefiles_write_complete;
+
+	ret = rw_verify_area(WRITE, file, &ki->iocb.ki_pos, iov_iter_count(iter));
+	if (ret < 0)
+		goto presubmission_error_free;
+
+	/* Open-code file_start_write here to grab freeze protection, which
+	 * will be released by another thread in aio_complete_rw().  Fool
+	 * lockdep by telling it the lock got released so that it doesn't
+	 * complain about the held lock when we return to userspace.
+	 */
+	inode = file_inode(file);
+	__sb_start_write(inode->i_sb, SB_FREEZE_WRITE);
+	__sb_writers_release(inode->i_sb, SB_FREEZE_WRITE);
+
+	get_file(ki->iocb.ki_filp);
+
+	old_nofs = memalloc_nofs_save();
+	ret = call_write_iter(file, &ki->iocb, iter);
+	memalloc_nofs_restore(old_nofs);
+	switch (ret) {
+	case -EIOCBQUEUED:
+		goto in_progress;
+
+	case -ERESTARTSYS:
+	case -ERESTARTNOINTR:
+	case -ERESTARTNOHAND:
+	case -ERESTART_RESTARTBLOCK:
+		/* There's no easy way to restart the syscall since other AIO's
+		 * may be already running. Just fail this IO with EINTR.
+		 */
+		ret = -EINTR;
+		/* Fall through */
+	default:
+		cachefiles_write_complete(&ki->iocb, ret, 0);
+		if (ret > 0)
+			ret = 0;
+		break;
+	}
+
+in_progress:
+	cachefiles_put_kiocb(ki);
+	_leave(" = %zd", ret);
+	return ret;
+
+presubmission_error_free:
+	kfree(ki);
+presubmission_error:
+	if (term_func)
+		term_func(term_func_priv, -ENOMEM);
+	return -ENOMEM;
+}
+
+/*
+ * Prepare a read operation, shortening it to a cached/uncached
+ * boundary as appropriate.
+ */
+static enum netfs_read_source cachefiles_prepare_read(struct netfs_read_subrequest *subreq,
+						      loff_t i_size)
+{
+	struct fscache_retrieval *op = subreq->rreq->cache_resources.cache_priv;
+	struct cachefiles_object *object;
+	struct cachefiles_cache *cache;
+	const struct cred *saved_cred;
+	struct file *file = subreq->rreq->cache_resources.cache_priv2;
+	loff_t off, to;
+
+	_enter("%zx @%llx/%llx", subreq->len, subreq->start, i_size);
+
+	object = container_of(op->op.object,
+			      struct cachefiles_object, fscache);
+	cache = container_of(object->fscache.cache,
+			     struct cachefiles_cache, cache);
+
+	if (!file)
+		goto cache_fail_nosec;
+
+	if (subreq->start >= i_size)
+		return NETFS_FILL_WITH_ZEROES;
+
+	cachefiles_begin_secure(cache, &saved_cred);
+
+	off = vfs_llseek(file, subreq->start, SEEK_DATA);
+	if (off < 0 && off >= (loff_t)-MAX_ERRNO) {
+		if (off == (loff_t)-ENXIO)
+			goto download_and_store;
+		goto cache_fail;
+	}
+
+	if (off >= subreq->start + subreq->len)
+		goto download_and_store;
+
+	if (off > subreq->start) {
+		off = round_up(off, cache->bsize);
+		subreq->len = off - subreq->start;
+		goto download_and_store;
+	}
+
+	to = vfs_llseek(file, subreq->start, SEEK_HOLE);
+	if (to < 0 && to >= (loff_t)-MAX_ERRNO)
+		goto cache_fail;
+
+	if (to < subreq->start + subreq->len) {
+		if (subreq->start + subreq->len >= i_size)
+			to = round_up(to, cache->bsize);
+		else
+			to = round_down(to, cache->bsize);
+		subreq->len = to - subreq->start;
+	}
+
+	cachefiles_end_secure(cache, saved_cred);
+	return NETFS_READ_FROM_CACHE;
+
+download_and_store:
+	if (cachefiles_has_space(cache, 0, (subreq->len + PAGE_SIZE - 1) / PAGE_SIZE) == 0)
+		__set_bit(NETFS_SREQ_WRITE_TO_CACHE, &subreq->flags);
+cache_fail:
+	cachefiles_end_secure(cache, saved_cred);
+cache_fail_nosec:
+	return NETFS_DOWNLOAD_FROM_SERVER;
+}
+
+/*
+ * Clean up an operation.
+ */
+static void cachefiles_end_operation(struct netfs_cache_resources *cres)
+{
+	struct fscache_retrieval *op = cres->cache_priv;
+	struct file *file = cres->cache_priv2;
+
+	_enter("");
+
+	if (file)
+		fput(file);
+	if (op) {
+		fscache_op_complete(&op->op, false);
+		fscache_put_retrieval(op);
+	}
+
+	_leave("");
+}
+
+static const struct netfs_cache_ops cachefiles_netfs_cache_ops = {
+	.end_operation		= cachefiles_end_operation,
+	.read			= cachefiles_read,
+	.write			= cachefiles_write,
+	.expand_readahead	= NULL,
+	.prepare_read		= cachefiles_prepare_read,
+};
+
+/*
+ * Open the cache file when beginning a cache operation.
+ */
+int cachefiles_begin_read_operation(struct netfs_read_request *rreq,
+				    struct fscache_retrieval *op)
+{
+	struct cachefiles_object *object;
+	struct cachefiles_cache *cache;
+	struct path path;
+	struct file *file;
+
+	_enter("");
+
+	object = container_of(op->op.object,
+			      struct cachefiles_object, fscache);
+	cache = container_of(object->fscache.cache,
+			     struct cachefiles_cache, cache);
+
+	path.mnt = cache->mnt;
+	path.dentry = object->backer;
+	file = open_with_fake_path(&path, O_RDWR | O_LARGEFILE | O_DIRECT,
+				   d_inode(object->backer), cache->cache_cred);
+	if (IS_ERR(file))
+		return PTR_ERR(file);
+	if (!S_ISREG(file_inode(file)->i_mode))
+		goto error_file;
+	if (unlikely(!file->f_op->read_iter) ||
+	    unlikely(!file->f_op->write_iter)) {
+		pr_notice("Cache does not support read_iter and write_iter\n");
+		goto error_file;
+	}
+
+	fscache_get_retrieval(op);
+	rreq->cache_resources.cache_priv = op;
+	rreq->cache_resources.cache_priv2 = file;
+	rreq->cache_resources.ops = &cachefiles_netfs_cache_ops;
+	rreq->cookie_debug_id = object->fscache.debug_id;
+	_leave("");
+	return 0;
+
+error_file:
+	fput(file);
+	return -EIO;
+}
diff --git a/fs/fscache/Kconfig b/fs/fscache/Kconfig
index 5e796e6c38e5..427efa73b9bd 100644
--- a/fs/fscache/Kconfig
+++ b/fs/fscache/Kconfig
@@ -2,6 +2,7 @@
 
 config FSCACHE
 	tristate "General filesystem local caching manager"
+	select NETFS_SUPPORT
 	help
 	  This option enables a generic filesystem caching manager that can be
 	  used by various network and other filesystems to cache data locally.
diff --git a/fs/fscache/Makefile b/fs/fscache/Makefile
index 79e08e05ef84..38f28fec2aa3 100644
--- a/fs/fscache/Makefile
+++ b/fs/fscache/Makefile
@@ -11,7 +11,8 @@ fscache-y := \
 	netfs.o \
 	object.o \
 	operation.o \
-	page.o
+	page.o \
+	page2.o
 
 fscache-$(CONFIG_PROC_FS) += proc.o
 fscache-$(CONFIG_FSCACHE_STATS) += stats.o
diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
index 08e91efbce53..c42672cadf2d 100644
--- a/fs/fscache/internal.h
+++ b/fs/fscache/internal.h
@@ -142,6 +142,9 @@ extern int fscache_wait_for_operation_activation(struct fscache_object *,
 						 atomic_t *,
 						 atomic_t *);
 extern void fscache_invalidate_writes(struct fscache_cookie *);
+extern struct fscache_retrieval *fscache_alloc_retrieval(struct fscache_cookie *,
+							 struct address_space *,
+							 fscache_rw_complete_t, void *);
 
 /*
  * proc.c
diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index 26af6fdf1538..991b0a871744 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -299,7 +299,7 @@ static void fscache_release_retrieval_op(struct fscache_operation *_op)
 /*
  * allocate a retrieval op
  */
-static struct fscache_retrieval *fscache_alloc_retrieval(
+struct fscache_retrieval *fscache_alloc_retrieval(
 	struct fscache_cookie *cookie,
 	struct address_space *mapping,
 	fscache_rw_complete_t end_io_func,
diff --git a/fs/fscache/page2.c b/fs/fscache/page2.c
new file mode 100644
index 000000000000..e3bc7178d99f
--- /dev/null
+++ b/fs/fscache/page2.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Cache data I/O routines
+ *
+ * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#define FSCACHE_DEBUG_LEVEL PAGE
+#include <linux/module.h>
+#include <linux/fscache-cache.h>
+#include <linux/slab.h>
+#include <linux/netfs.h>
+#include "internal.h"
+
+/*
+ * Start a cache read operation.
+ * - we return:
+ *   -ENOMEM	- out of memory, some pages may be being read
+ *   -ERESTARTSYS - interrupted, some pages may be being read
+ *   -ENOBUFS	- no backing object or space available in which to cache any
+ *                pages not being read
+ *   -ENODATA	- no data available in the backing object for some or all of
+ *                the pages
+ *   0		- dispatched a read on all pages
+ */
+int __fscache_begin_read_operation(struct netfs_read_request *rreq,
+				   struct fscache_cookie *cookie)
+{
+	struct fscache_retrieval *op;
+	struct fscache_object *object;
+	bool wake_cookie = false;
+	int ret;
+
+	_enter("rr=%08x", rreq->debug_id);
+
+	fscache_stat(&fscache_n_retrievals);
+
+	if (hlist_empty(&cookie->backing_objects))
+		goto nobufs;
+
+	if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
+		_leave(" = -ENOBUFS [invalidating]");
+		return -ENOBUFS;
+	}
+
+	ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
+
+	if (fscache_wait_for_deferred_lookup(cookie) < 0)
+		return -ERESTARTSYS;
+
+	op = fscache_alloc_retrieval(cookie, NULL, NULL, NULL);
+	if (!op)
+		return -ENOMEM;
+	//atomic_set(&op->n_pages, 1);
+	trace_fscache_page_op(cookie, NULL, &op->op, fscache_page_op_retr_multi);
+
+	spin_lock(&cookie->lock);
+
+	if (!fscache_cookie_enabled(cookie) ||
+	    hlist_empty(&cookie->backing_objects))
+		goto nobufs_unlock;
+	object = hlist_entry(cookie->backing_objects.first,
+			     struct fscache_object, cookie_link);
+
+	__fscache_use_cookie(cookie);
+	atomic_inc(&object->n_reads);
+	__set_bit(FSCACHE_OP_DEC_READ_CNT, &op->op.flags);
+
+	if (fscache_submit_op(object, &op->op) < 0)
+		goto nobufs_unlock_dec;
+	spin_unlock(&cookie->lock);
+
+	fscache_stat(&fscache_n_retrieval_ops);
+
+	/* we wait for the operation to become active, and then process it
+	 * *here*, in this thread, and not in the thread pool */
+	ret = fscache_wait_for_operation_activation(
+		object, &op->op,
+		__fscache_stat(&fscache_n_retrieval_op_waits),
+		__fscache_stat(&fscache_n_retrievals_object_dead));
+	if (ret < 0)
+		goto error;
+
+	/* ask the cache to honour the operation */
+	ret = object->cache->ops->begin_read_operation(rreq, op);
+
+error:
+	if (ret == -ENOMEM)
+		fscache_stat(&fscache_n_retrievals_nomem);
+	else if (ret == -ERESTARTSYS)
+		fscache_stat(&fscache_n_retrievals_intr);
+	else if (ret == -ENODATA)
+		fscache_stat(&fscache_n_retrievals_nodata);
+	else if (ret < 0)
+		fscache_stat(&fscache_n_retrievals_nobufs);
+	else
+		fscache_stat(&fscache_n_retrievals_ok);
+
+	fscache_put_retrieval(op);
+	_leave(" = %d", ret);
+	return ret;
+
+nobufs_unlock_dec:
+	atomic_dec(&object->n_reads);
+	wake_cookie = __fscache_unuse_cookie(cookie);
+nobufs_unlock:
+	spin_unlock(&cookie->lock);
+	fscache_put_retrieval(op);
+	if (wake_cookie)
+		__fscache_wake_unused_cookie(cookie);
+nobufs:
+	fscache_stat(&fscache_n_retrievals_nobufs);
+	_leave(" = -ENOBUFS");
+	return -ENOBUFS;
+}
+EXPORT_SYMBOL(__fscache_begin_read_operation);
diff --git a/fs/fscache/stats.c b/fs/fscache/stats.c
index a5aa93ece8c5..a7c3ed89a3e0 100644
--- a/fs/fscache/stats.c
+++ b/fs/fscache/stats.c
@@ -278,5 +278,6 @@ int fscache_stats_show(struct seq_file *m, void *v)
 		   atomic_read(&fscache_n_cache_stale_objects),
 		   atomic_read(&fscache_n_cache_retired_objects),
 		   atomic_read(&fscache_n_cache_culled_objects));
+	netfs_stats_show(m);
 	return 0;
 }



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 12/32] afs: Disable use of the fscache I/O routines
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (10 preceding siblings ...)
  2021-01-25 21:32 ` [PATCH 11/32] fscache, cachefiles: Add alternate API to use kiocb for read/write to cache David Howells
@ 2021-01-25 21:33 ` David Howells
  2021-01-25 21:33 ` [PATCH 13/32] afs: Pass page into dirty region helpers to provide THP size David Howells
                   ` (19 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:33 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: linux-afs, dhowells, Jeff Layton, David Wysochanski,
	Matthew Wilcox, Alexander Viro, linux-cachefs, linux-afs,
	linux-nfs, linux-cifs, ceph-devel, v9fs-developer, linux-fsdevel,
	linux-kernel

Disable use of the fscache I/O routined by the AFS filesystem.  It's about
to transition to passing iov_iters down and fscache is about to have its
I/O path to use iov_iter, so all that needs to change.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-afs@lists.infradead.org
---

 fs/afs/file.c  |  199 ++++++++++----------------------------------------------
 fs/afs/inode.c |    2 -
 fs/afs/write.c |   10 ---
 3 files changed, 36 insertions(+), 175 deletions(-)

diff --git a/fs/afs/file.c b/fs/afs/file.c
index 85f5adf21aa0..6d43713fde01 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -203,24 +203,6 @@ void afs_put_read(struct afs_read *req)
 	}
 }
 
-#ifdef CONFIG_AFS_FSCACHE
-/*
- * deal with notification that a page was read from the cache
- */
-static void afs_file_readpage_read_complete(struct page *page,
-					    void *data,
-					    int error)
-{
-	_enter("%p,%p,%d", page, data, error);
-
-	/* if the read completes with an error, we just unlock the page and let
-	 * the VM reissue the readpage */
-	if (!error)
-		SetPageUptodate(page);
-	unlock_page(page);
-}
-#endif
-
 static void afs_fetch_data_success(struct afs_operation *op)
 {
 	struct afs_vnode *vnode = op->file[0].vnode;
@@ -288,89 +270,46 @@ int afs_page_filler(void *data, struct page *page)
 	if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
 		goto error;
 
-	/* is it cached? */
-#ifdef CONFIG_AFS_FSCACHE
-	ret = fscache_read_or_alloc_page(vnode->cache,
-					 page,
-					 afs_file_readpage_read_complete,
-					 NULL,
-					 GFP_KERNEL);
-#else
-	ret = -ENOBUFS;
-#endif
-	switch (ret) {
-		/* read BIO submitted (page in cache) */
-	case 0:
-		break;
-
-		/* page not yet cached */
-	case -ENODATA:
-		_debug("cache said ENODATA");
-		goto go_on;
-
-		/* page will not be cached */
-	case -ENOBUFS:
-		_debug("cache said ENOBUFS");
-
-		fallthrough;
-	default:
-	go_on:
-		req = kzalloc(struct_size(req, array, 1), GFP_KERNEL);
-		if (!req)
-			goto enomem;
-
-		/* We request a full page.  If the page is a partial one at the
-		 * end of the file, the server will return a short read and the
-		 * unmarshalling code will clear the unfilled space.
-		 */
-		refcount_set(&req->usage, 1);
-		req->pos = (loff_t)page->index << PAGE_SHIFT;
-		req->len = PAGE_SIZE;
-		req->nr_pages = 1;
-		req->pages = req->array;
-		req->pages[0] = page;
-		get_page(page);
-
-		/* read the contents of the file from the server into the
-		 * page */
-		ret = afs_fetch_data(vnode, key, req);
-		afs_put_read(req);
-
-		if (ret < 0) {
-			if (ret == -ENOENT) {
-				_debug("got NOENT from server"
-				       " - marking file deleted and stale");
-				set_bit(AFS_VNODE_DELETED, &vnode->flags);
-				ret = -ESTALE;
-			}
-
-#ifdef CONFIG_AFS_FSCACHE
-			fscache_uncache_page(vnode->cache, page);
-#endif
-			BUG_ON(PageFsCache(page));
-
-			if (ret == -EINTR ||
-			    ret == -ENOMEM ||
-			    ret == -ERESTARTSYS ||
-			    ret == -EAGAIN)
-				goto error;
-			goto io_error;
-		}
+	req = kzalloc(struct_size(req, array, 1), GFP_KERNEL);
+	if (!req)
+		goto enomem;
 
-		SetPageUptodate(page);
+	/* We request a full page.  If the page is a partial one at the
+	 * end of the file, the server will return a short read and the
+	 * unmarshalling code will clear the unfilled space.
+	 */
+	refcount_set(&req->usage, 1);
+	req->pos = (loff_t)page->index << PAGE_SHIFT;
+	req->len = PAGE_SIZE;
+	req->nr_pages = 1;
+	req->pages = req->array;
+	req->pages[0] = page;
+	get_page(page);
+
+	/* read the contents of the file from the server into the
+	 * page */
+	ret = afs_fetch_data(vnode, key, req);
+	afs_put_read(req);
 
-		/* send the page to the cache */
-#ifdef CONFIG_AFS_FSCACHE
-		if (PageFsCache(page) &&
-		    fscache_write_page(vnode->cache, page, vnode->status.size,
-				       GFP_KERNEL) != 0) {
-			fscache_uncache_page(vnode->cache, page);
-			BUG_ON(PageFsCache(page));
+	if (ret < 0) {
+		if (ret == -ENOENT) {
+			_debug("got NOENT from server"
+			       " - marking file deleted and stale");
+			set_bit(AFS_VNODE_DELETED, &vnode->flags);
+			ret = -ESTALE;
 		}
-#endif
-		unlock_page(page);
+
+		if (ret == -EINTR ||
+		    ret == -ENOMEM ||
+		    ret == -ERESTARTSYS ||
+		    ret == -EAGAIN)
+			goto error;
+		goto io_error;
 	}
 
+	SetPageUptodate(page);
+	unlock_page(page);
+
 	_leave(" = 0");
 	return 0;
 
@@ -416,23 +355,10 @@ static int afs_readpage(struct file *file, struct page *page)
  */
 static void afs_readpages_page_done(struct afs_read *req)
 {
-#ifdef CONFIG_AFS_FSCACHE
-	struct afs_vnode *vnode = req->vnode;
-#endif
 	struct page *page = req->pages[req->index];
 
 	req->pages[req->index] = NULL;
 	SetPageUptodate(page);
-
-	/* send the page to the cache */
-#ifdef CONFIG_AFS_FSCACHE
-	if (PageFsCache(page) &&
-	    fscache_write_page(vnode->cache, page, vnode->status.size,
-			       GFP_KERNEL) != 0) {
-		fscache_uncache_page(vnode->cache, page);
-		BUG_ON(PageFsCache(page));
-	}
-#endif
 	unlock_page(page);
 	put_page(page);
 }
@@ -491,9 +417,6 @@ static int afs_readpages_one(struct file *file, struct address_space *mapping,
 		index = page->index;
 		if (add_to_page_cache_lru(page, mapping, index,
 					  readahead_gfp_mask(mapping))) {
-#ifdef CONFIG_AFS_FSCACHE
-			fscache_uncache_page(vnode->cache, page);
-#endif
 			put_page(page);
 			break;
 		}
@@ -526,9 +449,6 @@ static int afs_readpages_one(struct file *file, struct address_space *mapping,
 	for (i = 0; i < req->nr_pages; i++) {
 		page = req->pages[i];
 		if (page) {
-#ifdef CONFIG_AFS_FSCACHE
-			fscache_uncache_page(vnode->cache, page);
-#endif
 			SetPageError(page);
 			unlock_page(page);
 		}
@@ -560,37 +480,6 @@ static int afs_readpages(struct file *file, struct address_space *mapping,
 	}
 
 	/* attempt to read as many of the pages as possible */
-#ifdef CONFIG_AFS_FSCACHE
-	ret = fscache_read_or_alloc_pages(vnode->cache,
-					  mapping,
-					  pages,
-					  &nr_pages,
-					  afs_file_readpage_read_complete,
-					  NULL,
-					  mapping_gfp_mask(mapping));
-#else
-	ret = -ENOBUFS;
-#endif
-
-	switch (ret) {
-		/* all pages are being read from the cache */
-	case 0:
-		BUG_ON(!list_empty(pages));
-		BUG_ON(nr_pages != 0);
-		_leave(" = 0 [reading all]");
-		return 0;
-
-		/* there were pages that couldn't be read from the cache */
-	case -ENODATA:
-	case -ENOBUFS:
-		break;
-
-		/* other error */
-	default:
-		_leave(" = %d", ret);
-		return ret;
-	}
-
 	while (!list_empty(pages)) {
 		ret = afs_readpages_one(file, mapping, pages);
 		if (ret < 0)
@@ -670,17 +559,6 @@ static void afs_invalidatepage(struct page *page, unsigned int offset,
 
 	BUG_ON(!PageLocked(page));
 
-#ifdef CONFIG_AFS_FSCACHE
-	/* we clean up only if the entire page is being invalidated */
-	if (offset == 0 && length == PAGE_SIZE) {
-		if (PageFsCache(page)) {
-			struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
-			fscache_wait_on_page_write(vnode->cache, page);
-			fscache_uncache_page(vnode->cache, page);
-		}
-	}
-#endif
-
 	if (PagePrivate(page))
 		afs_invalidate_dirty(page, offset, length);
 
@@ -702,13 +580,6 @@ static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 
 	/* deny if page is being written to the cache and the caller hasn't
 	 * elected to wait */
-#ifdef CONFIG_AFS_FSCACHE
-	if (!fscache_maybe_release_page(vnode->cache, page, gfp_flags)) {
-		_leave(" = F [cache busy]");
-		return 0;
-	}
-#endif
-
 	if (PagePrivate(page)) {
 		priv = (unsigned long)detach_page_private(page);
 		trace_afs_page_dirty(vnode, tracepoint_string("rel"),
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index b0d7b892090d..48edd8d724d2 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -428,7 +428,7 @@ static void afs_get_inode_cache(struct afs_vnode *vnode)
 	} __packed key;
 	struct afs_vnode_cache_aux aux;
 
-	if (vnode->status.type == AFS_FTYPE_DIR) {
+	if (vnode->status.type != AFS_FTYPE_FILE) {
 		vnode->cache = NULL;
 		return;
 	}
diff --git a/fs/afs/write.c b/fs/afs/write.c
index c9195fc67fd8..92eaa88000d7 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -847,9 +847,6 @@ vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
 	/* Wait for the page to be written to the cache before we allow it to
 	 * be modified.  We then assume the entire page will need writing back.
 	 */
-#ifdef CONFIG_AFS_FSCACHE
-	fscache_wait_on_page_write(vnode->cache, vmf->page);
-#endif
 
 	if (PageWriteback(vmf->page) &&
 	    wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
@@ -936,12 +933,5 @@ int afs_launder_page(struct page *page)
 	priv = (unsigned long)detach_page_private(page);
 	trace_afs_page_dirty(vnode, tracepoint_string("laundered"),
 			     page->index, priv);
-
-#ifdef CONFIG_AFS_FSCACHE
-	if (PageFsCache(page)) {
-		fscache_wait_on_page_write(vnode->cache, page);
-		fscache_uncache_page(vnode->cache, page);
-	}
-#endif
 	return ret;
 }



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 13/32] afs: Pass page into dirty region helpers to provide THP size
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (11 preceding siblings ...)
  2021-01-25 21:33 ` [PATCH 12/32] afs: Disable use of the fscache I/O routines David Howells
@ 2021-01-25 21:33 ` David Howells
  2021-01-25 21:33 ` [PATCH 14/32] afs: Print the operation debug_id when logging an unexpected data version David Howells
                   ` (18 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:33 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Pass a pointer to the page being accessed into the dirty region helpers so
that the size of the page can be determined in case it's a transparent huge
page.

This also required the page to be passed into the afs_page_dirty trace
point - so there's no need to specifically pass in the index or private
data as these can be retrieved directly from the page struct.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/file.c              |   20 +++++++--------
 fs/afs/internal.h          |   16 ++++++------
 fs/afs/write.c             |   60 ++++++++++++++++++--------------------------
 include/trace/events/afs.h |   23 ++++++++++-------
 4 files changed, 55 insertions(+), 64 deletions(-)

diff --git a/fs/afs/file.c b/fs/afs/file.c
index 6d43713fde01..21868bfc3a44 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -515,8 +515,8 @@ static void afs_invalidate_dirty(struct page *page, unsigned int offset,
 		return;
 
 	/* We may need to shorten the dirty region */
-	f = afs_page_dirty_from(priv);
-	t = afs_page_dirty_to(priv);
+	f = afs_page_dirty_from(page, priv);
+	t = afs_page_dirty_to(page, priv);
 
 	if (t <= offset || f >= end)
 		return; /* Doesn't overlap */
@@ -534,17 +534,17 @@ static void afs_invalidate_dirty(struct page *page, unsigned int offset,
 	if (f == t)
 		goto undirty;
 
-	priv = afs_page_dirty(f, t);
+	priv = afs_page_dirty(page, f, t);
 	set_page_private(page, priv);
-	trace_afs_page_dirty(vnode, tracepoint_string("trunc"), page->index, priv);
+	trace_afs_page_dirty(vnode, tracepoint_string("trunc"), page);
 	return;
 
 undirty:
-	trace_afs_page_dirty(vnode, tracepoint_string("undirty"), page->index, priv);
+	trace_afs_page_dirty(vnode, tracepoint_string("undirty"), page);
 	clear_page_dirty_for_io(page);
 full_invalidate:
-	priv = (unsigned long)detach_page_private(page);
-	trace_afs_page_dirty(vnode, tracepoint_string("inval"), page->index, priv);
+	detach_page_private(page);
+	trace_afs_page_dirty(vnode, tracepoint_string("inval"), page);
 }
 
 /*
@@ -572,7 +572,6 @@ static void afs_invalidatepage(struct page *page, unsigned int offset,
 static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 {
 	struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
-	unsigned long priv;
 
 	_enter("{{%llx:%llu}[%lu],%lx},%x",
 	       vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
@@ -581,9 +580,8 @@ static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 	/* deny if page is being written to the cache and the caller hasn't
 	 * elected to wait */
 	if (PagePrivate(page)) {
-		priv = (unsigned long)detach_page_private(page);
-		trace_afs_page_dirty(vnode, tracepoint_string("rel"),
-				     page->index, priv);
+		detach_page_private(page);
+		trace_afs_page_dirty(vnode, tracepoint_string("rel"), page);
 	}
 
 	/* indicate that the page can be released */
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 0d150a29e39e..cd545e7dbfb8 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -875,31 +875,31 @@ struct afs_vnode_cache_aux {
 #define __AFS_PAGE_PRIV_MMAPPED	0x8000UL
 #endif
 
-static inline unsigned int afs_page_dirty_resolution(void)
+static inline unsigned int afs_page_dirty_resolution(struct page *page)
 {
-	int shift = PAGE_SHIFT - (__AFS_PAGE_PRIV_SHIFT - 1);
+	int shift = thp_order(page) + PAGE_SHIFT - (__AFS_PAGE_PRIV_SHIFT - 1);
 	return (shift > 0) ? shift : 0;
 }
 
-static inline size_t afs_page_dirty_from(unsigned long priv)
+static inline size_t afs_page_dirty_from(struct page *page, unsigned long priv)
 {
 	unsigned long x = priv & __AFS_PAGE_PRIV_MASK;
 
 	/* The lower bound is inclusive */
-	return x << afs_page_dirty_resolution();
+	return x << afs_page_dirty_resolution(page);
 }
 
-static inline size_t afs_page_dirty_to(unsigned long priv)
+static inline size_t afs_page_dirty_to(struct page *page, unsigned long priv)
 {
 	unsigned long x = (priv >> __AFS_PAGE_PRIV_SHIFT) & __AFS_PAGE_PRIV_MASK;
 
 	/* The upper bound is immediately beyond the region */
-	return (x + 1) << afs_page_dirty_resolution();
+	return (x + 1) << afs_page_dirty_resolution(page);
 }
 
-static inline unsigned long afs_page_dirty(size_t from, size_t to)
+static inline unsigned long afs_page_dirty(struct page *page, size_t from, size_t to)
 {
-	unsigned int res = afs_page_dirty_resolution();
+	unsigned int res = afs_page_dirty_resolution(page);
 	from >>= res;
 	to = (to - 1) >> res;
 	return (to << __AFS_PAGE_PRIV_SHIFT) | from;
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 92eaa88000d7..9d0cef35ecba 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -112,15 +112,14 @@ int afs_write_begin(struct file *file, struct address_space *mapping,
 	t = f = 0;
 	if (PagePrivate(page)) {
 		priv = page_private(page);
-		f = afs_page_dirty_from(priv);
-		t = afs_page_dirty_to(priv);
+		f = afs_page_dirty_from(page, priv);
+		t = afs_page_dirty_to(page, priv);
 		ASSERTCMP(f, <=, t);
 	}
 
 	if (f != t) {
 		if (PageWriteback(page)) {
-			trace_afs_page_dirty(vnode, tracepoint_string("alrdy"),
-					     page->index, priv);
+			trace_afs_page_dirty(vnode, tracepoint_string("alrdy"), page);
 			goto flush_conflicting_write;
 		}
 		/* If the file is being filled locally, allow inter-write
@@ -204,21 +203,19 @@ int afs_write_end(struct file *file, struct address_space *mapping,
 
 	if (PagePrivate(page)) {
 		priv = page_private(page);
-		f = afs_page_dirty_from(priv);
-		t = afs_page_dirty_to(priv);
+		f = afs_page_dirty_from(page, priv);
+		t = afs_page_dirty_to(page, priv);
 		if (from < f)
 			f = from;
 		if (to > t)
 			t = to;
-		priv = afs_page_dirty(f, t);
+		priv = afs_page_dirty(page, f, t);
 		set_page_private(page, priv);
-		trace_afs_page_dirty(vnode, tracepoint_string("dirty+"),
-				     page->index, priv);
+		trace_afs_page_dirty(vnode, tracepoint_string("dirty+"), page);
 	} else {
-		priv = afs_page_dirty(from, to);
+		priv = afs_page_dirty(page, from, to);
 		attach_page_private(page, (void *)priv);
-		trace_afs_page_dirty(vnode, tracepoint_string("dirty"),
-				     page->index, priv);
+		trace_afs_page_dirty(vnode, tracepoint_string("dirty"), page);
 	}
 
 	set_page_dirty(page);
@@ -321,7 +318,6 @@ static void afs_pages_written_back(struct afs_vnode *vnode,
 				   pgoff_t first, pgoff_t last)
 {
 	struct pagevec pv;
-	unsigned long priv;
 	unsigned count, loop;
 
 	_enter("{%llx:%llu},{%lx-%lx}",
@@ -340,9 +336,9 @@ static void afs_pages_written_back(struct afs_vnode *vnode,
 		ASSERTCMP(pv.nr, ==, count);
 
 		for (loop = 0; loop < count; loop++) {
-			priv = (unsigned long)detach_page_private(pv.pages[loop]);
+			detach_page_private(pv.pages[loop]);
 			trace_afs_page_dirty(vnode, tracepoint_string("clear"),
-					     pv.pages[loop]->index, priv);
+					     pv.pages[loop]);
 			end_page_writeback(pv.pages[loop]);
 		}
 		first += count;
@@ -516,15 +512,13 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
 	 */
 	start = primary_page->index;
 	priv = page_private(primary_page);
-	offset = afs_page_dirty_from(priv);
-	to = afs_page_dirty_to(priv);
-	trace_afs_page_dirty(vnode, tracepoint_string("store"),
-			     primary_page->index, priv);
+	offset = afs_page_dirty_from(primary_page, priv);
+	to = afs_page_dirty_to(primary_page, priv);
+	trace_afs_page_dirty(vnode, tracepoint_string("store"), primary_page);
 
 	WARN_ON(offset == to);
 	if (offset == to)
-		trace_afs_page_dirty(vnode, tracepoint_string("WARN"),
-				     primary_page->index, priv);
+		trace_afs_page_dirty(vnode, tracepoint_string("WARN"), primary_page);
 
 	if (start >= final_page ||
 	    (to < PAGE_SIZE && !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)))
@@ -562,8 +556,8 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
 			}
 
 			priv = page_private(page);
-			f = afs_page_dirty_from(priv);
-			t = afs_page_dirty_to(priv);
+			f = afs_page_dirty_from(page, priv);
+			t = afs_page_dirty_to(page, priv);
 			if (f != 0 &&
 			    !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)) {
 				unlock_page(page);
@@ -571,8 +565,7 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
 			}
 			to = t;
 
-			trace_afs_page_dirty(vnode, tracepoint_string("store+"),
-					     page->index, priv);
+			trace_afs_page_dirty(vnode, tracepoint_string("store+"), page);
 
 			if (!clear_page_dirty_for_io(page))
 				BUG();
@@ -861,14 +854,13 @@ vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
 	 */
 	wait_on_page_writeback(vmf->page);
 
-	priv = afs_page_dirty(0, PAGE_SIZE);
+	priv = afs_page_dirty(vmf->page, 0, PAGE_SIZE);
 	priv = afs_page_dirty_mmapped(priv);
-	trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"),
-			     vmf->page->index, priv);
 	if (PagePrivate(vmf->page))
 		set_page_private(vmf->page, priv);
 	else
 		attach_page_private(vmf->page, (void *)priv);
+	trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"), vmf->page);
 	file_update_time(file);
 
 	sb_end_pagefault(inode->i_sb);
@@ -921,17 +913,15 @@ int afs_launder_page(struct page *page)
 		f = 0;
 		t = PAGE_SIZE;
 		if (PagePrivate(page)) {
-			f = afs_page_dirty_from(priv);
-			t = afs_page_dirty_to(priv);
+			f = afs_page_dirty_from(page, priv);
+			t = afs_page_dirty_to(page, priv);
 		}
 
-		trace_afs_page_dirty(vnode, tracepoint_string("launder"),
-				     page->index, priv);
+		trace_afs_page_dirty(vnode, tracepoint_string("launder"), page);
 		ret = afs_store_data(mapping, page->index, page->index, t, f, true);
 	}
 
-	priv = (unsigned long)detach_page_private(page);
-	trace_afs_page_dirty(vnode, tracepoint_string("laundered"),
-			     page->index, priv);
+	detach_page_private(page);
+	trace_afs_page_dirty(vnode, tracepoint_string("laundered"), page);
 	return ret;
 }
diff --git a/include/trace/events/afs.h b/include/trace/events/afs.h
index 4a5cc8c64be3..9203cf6a8c53 100644
--- a/include/trace/events/afs.h
+++ b/include/trace/events/afs.h
@@ -969,30 +969,33 @@ TRACE_EVENT(afs_dir_check_failed,
 	    );
 
 TRACE_EVENT(afs_page_dirty,
-	    TP_PROTO(struct afs_vnode *vnode, const char *where,
-		     pgoff_t page, unsigned long priv),
+	    TP_PROTO(struct afs_vnode *vnode, const char *where, struct page *page),
 
-	    TP_ARGS(vnode, where, page, priv),
+	    TP_ARGS(vnode, where, page),
 
 	    TP_STRUCT__entry(
 		    __field(struct afs_vnode *,		vnode		)
 		    __field(const char *,		where		)
 		    __field(pgoff_t,			page		)
-		    __field(unsigned long,		priv		)
+		    __field(unsigned long,		from		)
+		    __field(unsigned long,		to		)
 			     ),
 
 	    TP_fast_assign(
 		    __entry->vnode = vnode;
 		    __entry->where = where;
-		    __entry->page = page;
-		    __entry->priv = priv;
+		    __entry->page = page->index;
+		    __entry->from = afs_page_dirty_from(page, page->private);
+		    __entry->to = afs_page_dirty_to(page, page->private);
+		    __entry->to |= (afs_is_page_dirty_mmapped(page->private) ?
+				    (1UL << (BITS_PER_LONG - 1)) : 0);
 			   ),
 
-	    TP_printk("vn=%p %lx %s %zx-%zx%s",
+	    TP_printk("vn=%p %lx %s %lx-%lx%s",
 		      __entry->vnode, __entry->page, __entry->where,
-		      afs_page_dirty_from(__entry->priv),
-		      afs_page_dirty_to(__entry->priv),
-		      afs_is_page_dirty_mmapped(__entry->priv) ? " M" : "")
+		      __entry->from,
+		      __entry->to & ~(1UL << (BITS_PER_LONG - 1)),
+		      __entry->to & (1UL << (BITS_PER_LONG - 1)) ? " M" : "")
 	    );
 
 TRACE_EVENT(afs_call_state,



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 14/32] afs: Print the operation debug_id when logging an unexpected data version
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (12 preceding siblings ...)
  2021-01-25 21:33 ` [PATCH 13/32] afs: Pass page into dirty region helpers to provide THP size David Howells
@ 2021-01-25 21:33 ` David Howells
  2021-01-25 21:33 ` [PATCH 15/32] afs: Move key to afs_read struct David Howells
                   ` (17 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:33 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Print the afs_operation debug_id when logging an unexpected change in the
data version.  This allows the logged message to be matched against
tracelines.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/inode.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 48edd8d724d2..0bc7273100b8 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -215,11 +215,12 @@ static void afs_apply_status(struct afs_operation *op,
 
 	if (vp->dv_before + vp->dv_delta != status->data_version) {
 		if (test_bit(AFS_VNODE_CB_PROMISED, &vnode->flags))
-			pr_warn("kAFS: vnode modified {%llx:%llu} %llx->%llx %s\n",
+			pr_warn("kAFS: vnode modified {%llx:%llu} %llx->%llx %s (op=%x)\n",
 				vnode->fid.vid, vnode->fid.vnode,
 				(unsigned long long)vp->dv_before + vp->dv_delta,
 				(unsigned long long)status->data_version,
-				op->type ? op->type->name : "???");
+				op->type ? op->type->name : "???",
+				op->debug_id);
 
 		vnode->invalid_before = status->data_version;
 		if (vnode->status.type == AFS_FTYPE_DIR) {



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 15/32] afs: Move key to afs_read struct
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (13 preceding siblings ...)
  2021-01-25 21:33 ` [PATCH 14/32] afs: Print the operation debug_id when logging an unexpected data version David Howells
@ 2021-01-25 21:33 ` David Howells
  2021-01-25 21:34 ` [PATCH 16/32] afs: Don't truncate iter during data fetch David Howells
                   ` (16 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:33 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Stash the key used to authenticate read operations in the afs_read struct.
This will be necessary to reissue the operation against the server if a
read from the cache fails in upcoming cache changes.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/dir.c      |    3 ++-
 fs/afs/file.c     |   16 +++++++++-------
 fs/afs/internal.h |    3 ++-
 fs/afs/write.c    |   12 ++++++------
 4 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index 7bd659ad959e..96e9e2e60d97 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -241,6 +241,7 @@ static struct afs_read *afs_read_dir(struct afs_vnode *dvnode, struct key *key)
 		return ERR_PTR(-ENOMEM);
 
 	refcount_set(&req->usage, 1);
+	req->key = key_get(key);
 	req->nr_pages = nr_pages;
 	req->actual_len = i_size; /* May change */
 	req->len = nr_pages * PAGE_SIZE; /* We can ask for more than there is */
@@ -305,7 +306,7 @@ static struct afs_read *afs_read_dir(struct afs_vnode *dvnode, struct key *key)
 
 	if (!test_bit(AFS_VNODE_DIR_VALID, &dvnode->flags)) {
 		trace_afs_reload_dir(dvnode);
-		ret = afs_fetch_data(dvnode, key, req);
+		ret = afs_fetch_data(dvnode, req);
 		if (ret < 0)
 			goto error_unlock;
 
diff --git a/fs/afs/file.c b/fs/afs/file.c
index 21868bfc3a44..d23192b3b933 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -199,6 +199,7 @@ void afs_put_read(struct afs_read *req)
 			if (req->pages != req->array)
 				kfree(req->pages);
 		}
+		key_put(req->key);
 		kfree(req);
 	}
 }
@@ -229,7 +230,7 @@ static const struct afs_operation_ops afs_fetch_data_operation = {
 /*
  * Fetch file data from the volume.
  */
-int afs_fetch_data(struct afs_vnode *vnode, struct key *key, struct afs_read *req)
+int afs_fetch_data(struct afs_vnode *vnode, struct afs_read *req)
 {
 	struct afs_operation *op;
 
@@ -238,9 +239,9 @@ int afs_fetch_data(struct afs_vnode *vnode, struct key *key, struct afs_read *re
 	       vnode->fid.vid,
 	       vnode->fid.vnode,
 	       vnode->fid.unique,
-	       key_serial(key));
+	       key_serial(req->key));
 
-	op = afs_alloc_operation(key, vnode->volume);
+	op = afs_alloc_operation(req->key, vnode->volume);
 	if (IS_ERR(op))
 		return PTR_ERR(op);
 
@@ -279,6 +280,7 @@ int afs_page_filler(void *data, struct page *page)
 	 * unmarshalling code will clear the unfilled space.
 	 */
 	refcount_set(&req->usage, 1);
+	req->key = key_get(key);
 	req->pos = (loff_t)page->index << PAGE_SHIFT;
 	req->len = PAGE_SIZE;
 	req->nr_pages = 1;
@@ -288,7 +290,7 @@ int afs_page_filler(void *data, struct page *page)
 
 	/* read the contents of the file from the server into the
 	 * page */
-	ret = afs_fetch_data(vnode, key, req);
+	ret = afs_fetch_data(vnode, req);
 	afs_put_read(req);
 
 	if (ret < 0) {
@@ -373,7 +375,6 @@ static int afs_readpages_one(struct file *file, struct address_space *mapping,
 	struct afs_read *req;
 	struct list_head *p;
 	struct page *first, *page;
-	struct key *key = afs_file_key(file);
 	pgoff_t index;
 	int ret, n, i;
 
@@ -397,6 +398,7 @@ static int afs_readpages_one(struct file *file, struct address_space *mapping,
 
 	refcount_set(&req->usage, 1);
 	req->vnode = vnode;
+	req->key = key_get(afs_file_key(file));
 	req->page_done = afs_readpages_page_done;
 	req->pos = first->index;
 	req->pos <<= PAGE_SHIFT;
@@ -426,11 +428,11 @@ static int afs_readpages_one(struct file *file, struct address_space *mapping,
 	} while (req->nr_pages < n);
 
 	if (req->nr_pages == 0) {
-		kfree(req);
+		afs_put_read(req);
 		return 0;
 	}
 
-	ret = afs_fetch_data(vnode, key, req);
+	ret = afs_fetch_data(vnode, req);
 	if (ret < 0)
 		goto error;
 
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index cd545e7dbfb8..4b255d10f726 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -204,6 +204,7 @@ struct afs_read {
 	loff_t			actual_len;	/* How much we're actually getting */
 	loff_t			remain;		/* Amount remaining */
 	loff_t			file_size;	/* File size returned by server */
+	struct key		*key;		/* The key to use to reissue the read */
 	afs_dataversion_t	data_version;	/* Version number returned by server */
 	refcount_t		usage;
 	unsigned int		index;		/* Which page we're reading into */
@@ -1045,7 +1046,7 @@ extern int afs_cache_wb_key(struct afs_vnode *, struct afs_file *);
 extern void afs_put_wb_key(struct afs_wb_key *);
 extern int afs_open(struct inode *, struct file *);
 extern int afs_release(struct inode *, struct file *);
-extern int afs_fetch_data(struct afs_vnode *, struct key *, struct afs_read *);
+extern int afs_fetch_data(struct afs_vnode *, struct afs_read *);
 extern int afs_page_filler(void *, struct page *);
 extern void afs_put_read(struct afs_read *);
 
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 9d0cef35ecba..7eba0d3201ba 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -25,9 +25,10 @@ int afs_set_page_dirty(struct page *page)
 /*
  * partly or wholly fill a page that's under preparation for writing
  */
-static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
+static int afs_fill_page(struct file *file,
 			 loff_t pos, unsigned int len, struct page *page)
 {
+	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 	struct afs_read *req;
 	size_t p;
 	void *data;
@@ -49,6 +50,7 @@ static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
 		return -ENOMEM;
 
 	refcount_set(&req->usage, 1);
+	req->key = key_get(afs_file_key(file));
 	req->pos = pos;
 	req->len = len;
 	req->nr_pages = 1;
@@ -56,7 +58,7 @@ static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
 	req->pages[0] = page;
 	get_page(page);
 
-	ret = afs_fetch_data(vnode, key, req);
+	ret = afs_fetch_data(vnode, req);
 	afs_put_read(req);
 	if (ret < 0) {
 		if (ret == -ENOENT) {
@@ -80,7 +82,6 @@ int afs_write_begin(struct file *file, struct address_space *mapping,
 {
 	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 	struct page *page;
-	struct key *key = afs_file_key(file);
 	unsigned long priv;
 	unsigned f, from = pos & (PAGE_SIZE - 1);
 	unsigned t, to = from + len;
@@ -95,7 +96,7 @@ int afs_write_begin(struct file *file, struct address_space *mapping,
 		return -ENOMEM;
 
 	if (!PageUptodate(page) && len != PAGE_SIZE) {
-		ret = afs_fill_page(vnode, key, pos & PAGE_MASK, PAGE_SIZE, page);
+		ret = afs_fill_page(file, pos & PAGE_MASK, PAGE_SIZE, page);
 		if (ret < 0) {
 			unlock_page(page);
 			put_page(page);
@@ -163,7 +164,6 @@ int afs_write_end(struct file *file, struct address_space *mapping,
 		  struct page *page, void *fsdata)
 {
 	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
-	struct key *key = afs_file_key(file);
 	unsigned long priv;
 	unsigned int f, from = pos & (PAGE_SIZE - 1);
 	unsigned int t, to = from + copied;
@@ -193,7 +193,7 @@ int afs_write_end(struct file *file, struct address_space *mapping,
 			 * unmarshalling routine will take care of clearing any
 			 * bits that are beyond the EOF.
 			 */
-			ret = afs_fill_page(vnode, key, pos + copied,
+			ret = afs_fill_page(file, pos + copied,
 					    len - copied, page);
 			if (ret < 0)
 				goto out;



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 16/32] afs: Don't truncate iter during data fetch
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (14 preceding siblings ...)
  2021-01-25 21:33 ` [PATCH 15/32] afs: Move key to afs_read struct David Howells
@ 2021-01-25 21:34 ` David Howells
  2021-01-25 21:34 ` [PATCH 17/32] afs: Log remote unmarshalling errors David Howells
                   ` (15 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:34 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Don't truncate the iterator to correspond to the actual data size when
fetching the data from the server - rather, pass the length we want to read
to rxrpc.

This will allow the clear-after-read code in future to simply clear the
remaining iterator capacity rather than having to reinitialise the
iterator.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/fsclient.c      |    6 ++++--
 fs/afs/internal.h      |    6 ++++++
 fs/afs/rxrpc.c         |   13 +++++++++----
 fs/afs/yfsclient.c     |    6 ++++--
 include/net/af_rxrpc.h |    2 +-
 net/rxrpc/recvmsg.c    |    9 +++++----
 6 files changed, 29 insertions(+), 13 deletions(-)

diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c
index 1d95ed9dd86e..4a57c6c6f12b 100644
--- a/fs/afs/fsclient.c
+++ b/fs/afs/fsclient.c
@@ -305,8 +305,9 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call)
 	unsigned int size;
 	int ret;
 
-	_enter("{%u,%zu/%llu}",
-	       call->unmarshall, iov_iter_count(call->iter), req->actual_len);
+	_enter("{%u,%zu,%zu/%llu}",
+	       call->unmarshall, call->iov_len, iov_iter_count(call->iter),
+	       req->actual_len);
 
 	switch (call->unmarshall) {
 	case 0:
@@ -343,6 +344,7 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call)
 			size = PAGE_SIZE - req->offset;
 		else
 			size = req->remain;
+		call->iov_len = size;
 		call->bvec[0].bv_len = size;
 		call->bvec[0].bv_offset = req->offset;
 		call->bvec[0].bv_page = req->pages[req->index];
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 4b255d10f726..1badc7ed0487 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -104,6 +104,7 @@ struct afs_call {
 	struct afs_server	*server;	/* The fileserver record if fs op (pins ref) */
 	struct afs_vlserver	*vlserver;	/* The vlserver record if vl op */
 	void			*request;	/* request data (first part) */
+	size_t			iov_len;	/* Size of *iter to be used */
 	struct iov_iter		def_iter;	/* Default buffer/data iterator */
 	struct iov_iter		*iter;		/* Iterator currently in use */
 	union {	/* Convenience for ->def_iter */
@@ -1270,6 +1271,7 @@ static inline void afs_make_op_call(struct afs_operation *op, struct afs_call *c
 
 static inline void afs_extract_begin(struct afs_call *call, void *buf, size_t size)
 {
+	call->iov_len = size;
 	call->kvec[0].iov_base = buf;
 	call->kvec[0].iov_len = size;
 	iov_iter_kvec(&call->def_iter, READ, call->kvec, 1, size);
@@ -1277,21 +1279,25 @@ static inline void afs_extract_begin(struct afs_call *call, void *buf, size_t si
 
 static inline void afs_extract_to_tmp(struct afs_call *call)
 {
+	call->iov_len = sizeof(call->tmp);
 	afs_extract_begin(call, &call->tmp, sizeof(call->tmp));
 }
 
 static inline void afs_extract_to_tmp64(struct afs_call *call)
 {
+	call->iov_len = sizeof(call->tmp64);
 	afs_extract_begin(call, &call->tmp64, sizeof(call->tmp64));
 }
 
 static inline void afs_extract_discard(struct afs_call *call, size_t size)
 {
+	call->iov_len = size;
 	iov_iter_discard(&call->def_iter, READ, size);
 }
 
 static inline void afs_extract_to_buf(struct afs_call *call, size_t size)
 {
+	call->iov_len = size;
 	afs_extract_begin(call, call->buffer, size);
 }
 
diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index 8be709cb8542..0ec38b758f29 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -363,6 +363,7 @@ void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp)
 	struct rxrpc_call *rxcall;
 	struct msghdr msg;
 	struct kvec iov[1];
+	size_t len;
 	s64 tx_total_len;
 	int ret;
 
@@ -466,9 +467,10 @@ void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp)
 		rxrpc_kernel_abort_call(call->net->socket, rxcall,
 					RX_USER_ABORT, ret, "KSD");
 	} else {
+		len = 0;
 		iov_iter_kvec(&msg.msg_iter, READ, NULL, 0, 0);
 		rxrpc_kernel_recv_data(call->net->socket, rxcall,
-				       &msg.msg_iter, false,
+				       &msg.msg_iter, &len, false,
 				       &call->abort_code, &call->service_id);
 		ac->abort_code = call->abort_code;
 		ac->responded = true;
@@ -504,6 +506,7 @@ void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp)
 static void afs_deliver_to_call(struct afs_call *call)
 {
 	enum afs_call_state state;
+	size_t len;
 	u32 abort_code, remote_abort = 0;
 	int ret;
 
@@ -516,10 +519,11 @@ static void afs_deliver_to_call(struct afs_call *call)
 	       state == AFS_CALL_SV_AWAIT_ACK
 	       ) {
 		if (state == AFS_CALL_SV_AWAIT_ACK) {
+			len = 0;
 			iov_iter_kvec(&call->def_iter, READ, NULL, 0, 0);
 			ret = rxrpc_kernel_recv_data(call->net->socket,
 						     call->rxcall, &call->def_iter,
-						     false, &remote_abort,
+						     &len, false, &remote_abort,
 						     &call->service_id);
 			trace_afs_receive_data(call, &call->def_iter, false, ret);
 
@@ -929,10 +933,11 @@ int afs_extract_data(struct afs_call *call, bool want_more)
 	u32 remote_abort = 0;
 	int ret;
 
-	_enter("{%s,%zu},%d", call->type->name, iov_iter_count(iter), want_more);
+	_enter("{%s,%zu,%zu},%d",
+	       call->type->name, call->iov_len, iov_iter_count(iter), want_more);
 
 	ret = rxrpc_kernel_recv_data(net->socket, call->rxcall, iter,
-				     want_more, &remote_abort,
+				     &call->iov_len, want_more, &remote_abort,
 				     &call->service_id);
 	if (ret == 0 || ret == -EAGAIN)
 		return ret;
diff --git a/fs/afs/yfsclient.c b/fs/afs/yfsclient.c
index bd787e71a657..6c45d32da13c 100644
--- a/fs/afs/yfsclient.c
+++ b/fs/afs/yfsclient.c
@@ -363,8 +363,9 @@ static int yfs_deliver_fs_fetch_data64(struct afs_call *call)
 	unsigned int size;
 	int ret;
 
-	_enter("{%u,%zu/%llu}",
-	       call->unmarshall, iov_iter_count(call->iter), req->actual_len);
+	_enter("{%u,%zu, %zu/%llu}",
+	       call->unmarshall, call->iov_len, iov_iter_count(call->iter),
+	       req->actual_len);
 
 	switch (call->unmarshall) {
 	case 0:
@@ -396,6 +397,7 @@ static int yfs_deliver_fs_fetch_data64(struct afs_call *call)
 			size = PAGE_SIZE - req->offset;
 		else
 			size = req->remain;
+		call->iov_len = size;
 		call->bvec[0].bv_len = size;
 		call->bvec[0].bv_offset = req->offset;
 		call->bvec[0].bv_page = req->pages[req->index];
diff --git a/include/net/af_rxrpc.h b/include/net/af_rxrpc.h
index f6abcc0bbd6e..cee5f83c0f11 100644
--- a/include/net/af_rxrpc.h
+++ b/include/net/af_rxrpc.h
@@ -53,7 +53,7 @@ int rxrpc_kernel_send_data(struct socket *, struct rxrpc_call *,
 			   struct msghdr *, size_t,
 			   rxrpc_notify_end_tx_t);
 int rxrpc_kernel_recv_data(struct socket *, struct rxrpc_call *,
-			   struct iov_iter *, bool, u32 *, u16 *);
+			   struct iov_iter *, size_t *, bool, u32 *, u16 *);
 bool rxrpc_kernel_abort_call(struct socket *, struct rxrpc_call *,
 			     u32, int, const char *);
 void rxrpc_kernel_end_call(struct socket *, struct rxrpc_call *);
diff --git a/net/rxrpc/recvmsg.c b/net/rxrpc/recvmsg.c
index fef3573fdc8b..eca6dda26c77 100644
--- a/net/rxrpc/recvmsg.c
+++ b/net/rxrpc/recvmsg.c
@@ -669,6 +669,7 @@ int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
  * @sock: The socket that the call exists on
  * @call: The call to send data through
  * @iter: The buffer to receive into
+ * @_len: The amount of data we want to receive (decreased on return)
  * @want_more: True if more data is expected to be read
  * @_abort: Where the abort code is stored if -ECONNABORTED is returned
  * @_service: Where to store the actual service ID (may be upgraded)
@@ -684,7 +685,7 @@ int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
  * *_abort should also be initialised to 0.
  */
 int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
-			   struct iov_iter *iter,
+			   struct iov_iter *iter, size_t *_len,
 			   bool want_more, u32 *_abort, u16 *_service)
 {
 	size_t offset = 0;
@@ -692,7 +693,7 @@ int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
 
 	_enter("{%d,%s},%zu,%d",
 	       call->debug_id, rxrpc_call_states[call->state],
-	       iov_iter_count(iter), want_more);
+	       *_len, want_more);
 
 	ASSERTCMP(call->state, !=, RXRPC_CALL_SERVER_SECURING);
 
@@ -703,8 +704,8 @@ int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
 	case RXRPC_CALL_SERVER_RECV_REQUEST:
 	case RXRPC_CALL_SERVER_ACK_REQUEST:
 		ret = rxrpc_recvmsg_data(sock, call, NULL, iter,
-					 iov_iter_count(iter), 0,
-					 &offset);
+					 *_len, 0, &offset);
+		*_len -= offset;
 		if (ret < 0)
 			goto out;
 



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 17/32] afs: Log remote unmarshalling errors
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (15 preceding siblings ...)
  2021-01-25 21:34 ` [PATCH 16/32] afs: Don't truncate iter during data fetch David Howells
@ 2021-01-25 21:34 ` David Howells
  2021-01-25 21:34 ` [PATCH 18/32] afs: Set up the iov_iter before calling afs_extract_data() David Howells
                   ` (14 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:34 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Log unmarshalling errors reported by the peer (ie. it can't parse what we
sent it).  Limit the maximum number of messages to 3.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/rxrpc.c |   34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index 0ec38b758f29..ae68576f822f 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -500,6 +500,39 @@ void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp)
 	_leave(" = %d", ret);
 }
 
+/*
+ * Log remote abort codes that indicate that we have a protocol disagreement
+ * with the server.
+ */
+static void afs_log_error(struct afs_call *call, s32 remote_abort)
+{
+	static int max = 0;
+	const char *msg;
+	int m;
+
+	switch (remote_abort) {
+	case RX_EOF:		 msg = "unexpected EOF";	break;
+	case RXGEN_CC_MARSHAL:	 msg = "client marshalling";	break;
+	case RXGEN_CC_UNMARSHAL: msg = "client unmarshalling";	break;
+	case RXGEN_SS_MARSHAL:	 msg = "server marshalling";	break;
+	case RXGEN_SS_UNMARSHAL: msg = "server unmarshalling";	break;
+	case RXGEN_DECODE:	 msg = "opcode decode";		break;
+	case RXGEN_SS_XDRFREE:	 msg = "server XDR cleanup";	break;
+	case RXGEN_CC_XDRFREE:	 msg = "client XDR cleanup";	break;
+	case -32:		 msg = "insufficient data";	break;
+	default:
+		return;
+	}
+
+	m = max;
+	if (m < 3) {
+		max = m + 1;
+		pr_notice("kAFS: Peer reported %s failure on %s [%pISp]\n",
+			  msg, call->type->name,
+			  &call->alist->addrs[call->addr_ix].transport);
+	}
+}
+
 /*
  * deliver messages to a call
  */
@@ -563,6 +596,7 @@ static void afs_deliver_to_call(struct afs_call *call)
 			goto out;
 		case -ECONNABORTED:
 			ASSERTCMP(state, ==, AFS_CALL_COMPLETE);
+			afs_log_error(call, call->abort_code);
 			goto done;
 		case -ENOTSUPP:
 			abort_code = RXGEN_OPCODE;



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 18/32] afs: Set up the iov_iter before calling afs_extract_data()
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (16 preceding siblings ...)
  2021-01-25 21:34 ` [PATCH 17/32] afs: Log remote unmarshalling errors David Howells
@ 2021-01-25 21:34 ` David Howells
  2021-01-25 21:34 ` [PATCH 19/32] afs: Use ITER_XARRAY for writing David Howells
                   ` (13 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:34 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

afs_extract_data() sets up a temporary iov_iter and passes it to AF_RXRPC
each time it is called to describe the remaining buffer to be filled.

Instead:

 (1) Put an iterator in the afs_call struct.

 (2) Set the iterator for each marshalling stage to load data into the
     appropriate places.  A number of convenience functions are provided to
     this end (eg. afs_extract_to_buf()).

     This iterator is then passed to afs_extract_data().

 (3) Use the new ITER_MAPPING iterator when reading data to load directly
     into the inode's pages without needing to create a list of them.

This will allow O_DIRECT calls to be supported in future patches.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/dir.c       |  222 +++++++++++++++++++++++++++++++++++-----------------
 fs/afs/file.c      |  190 ++++++++++++++++++++++++++-------------------
 fs/afs/fsclient.c  |   54 +++----------
 fs/afs/internal.h  |   16 ++--
 fs/afs/write.c     |   27 ++++--
 fs/afs/yfsclient.c |   54 +++----------
 6 files changed, 314 insertions(+), 249 deletions(-)

diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index 96e9e2e60d97..6439ea18667f 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -102,6 +102,35 @@ struct afs_lookup_cookie {
 	struct afs_fid		fids[50];
 };
 
+/*
+ * Drop the refs that we're holding on the pages we were reading into.  We've
+ * got refs on the first nr_pages pages.
+ */
+static void afs_dir_read_cleanup(struct afs_read *req)
+{
+	struct address_space *mapping = req->vnode->vfs_inode.i_mapping;
+	struct page *page;
+	pgoff_t last = req->nr_pages - 1;
+
+	XA_STATE(xas, &mapping->i_pages, 0);
+
+	if (unlikely(!req->nr_pages))
+		return;
+
+	rcu_read_lock();
+	xas_for_each(&xas, page, last) {
+		if (xas_retry(&xas, page))
+			continue;
+		BUG_ON(xa_is_value(page));
+		BUG_ON(PageCompound(page));
+		ASSERTCMP(page->mapping, ==, mapping);
+
+		put_page(page);
+	}
+
+	rcu_read_unlock();
+}
+
 /*
  * check that a directory page is valid
  */
@@ -127,7 +156,7 @@ static bool afs_dir_check_page(struct afs_vnode *dvnode, struct page *page,
 	qty /= sizeof(union afs_xdr_dir_block);
 
 	/* check them */
-	dbuf = kmap(page);
+	dbuf = kmap_atomic(page);
 	for (tmp = 0; tmp < qty; tmp++) {
 		if (dbuf->blocks[tmp].hdr.magic != AFS_DIR_MAGIC) {
 			printk("kAFS: %s(%lx): bad magic %d/%d is %04hx\n",
@@ -146,7 +175,7 @@ static bool afs_dir_check_page(struct afs_vnode *dvnode, struct page *page,
 		((u8 *)&dbuf->blocks[tmp])[AFS_DIR_BLOCK_SIZE - 1] = 0;
 	}
 
-	kunmap(page);
+	kunmap_atomic(dbuf);
 
 checked:
 	afs_stat_v(dvnode, n_read_dir);
@@ -157,35 +186,74 @@ static bool afs_dir_check_page(struct afs_vnode *dvnode, struct page *page,
 }
 
 /*
- * Check the contents of a directory that we've just read.
+ * Dump the contents of a directory.
  */
-static bool afs_dir_check_pages(struct afs_vnode *dvnode, struct afs_read *req)
+static void afs_dir_dump(struct afs_vnode *dvnode, struct afs_read *req)
 {
 	struct afs_xdr_dir_page *dbuf;
-	unsigned int i, j, qty = PAGE_SIZE / sizeof(union afs_xdr_dir_block);
+	struct address_space *mapping = dvnode->vfs_inode.i_mapping;
+	struct page *page;
+	unsigned int i, qty = PAGE_SIZE / sizeof(union afs_xdr_dir_block);
+	pgoff_t last = req->nr_pages - 1;
 
-	for (i = 0; i < req->nr_pages; i++)
-		if (!afs_dir_check_page(dvnode, req->pages[i], req->actual_len))
-			goto bad;
-	return true;
+	XA_STATE(xas, &mapping->i_pages, 0);
 
-bad:
-	pr_warn("DIR %llx:%llx f=%llx l=%llx al=%llx r=%llx\n",
+	pr_warn("DIR %llx:%llx f=%llx l=%llx al=%llx\n",
 		dvnode->fid.vid, dvnode->fid.vnode,
-		req->file_size, req->len, req->actual_len, req->remain);
-	pr_warn("DIR %llx %x %x %x\n",
-		req->pos, req->index, req->nr_pages, req->offset);
+		req->file_size, req->len, req->actual_len);
+	pr_warn("DIR %llx %x %zx %zx\n",
+		req->pos, req->nr_pages,
+		req->iter->iov_offset,  iov_iter_count(req->iter));
 
-	for (i = 0; i < req->nr_pages; i++) {
-		dbuf = kmap(req->pages[i]);
-		for (j = 0; j < qty; j++) {
-			union afs_xdr_dir_block *block = &dbuf->blocks[j];
+	xas_for_each(&xas, page, last) {
+		if (xas_retry(&xas, page))
+			continue;
+
+		BUG_ON(PageCompound(page));
+		BUG_ON(page->mapping != mapping);
+
+		dbuf = kmap_atomic(page);
+		for (i = 0; i < qty; i++) {
+			union afs_xdr_dir_block *block = &dbuf->blocks[i];
 
-			pr_warn("[%02x] %32phN\n", i * qty + j, block);
+			pr_warn("[%02lx] %32phN\n", page->index * qty + i, block);
 		}
-		kunmap(req->pages[i]);
+		kunmap_atomic(dbuf);
 	}
-	return false;
+}
+
+/*
+ * Check all the pages in a directory.  All the pages are held pinned.
+ */
+static int afs_dir_check(struct afs_vnode *dvnode, struct afs_read *req)
+{
+	struct address_space *mapping = dvnode->vfs_inode.i_mapping;
+	struct page *page;
+	pgoff_t last = req->nr_pages - 1;
+	int ret = 0;
+
+	XA_STATE(xas, &mapping->i_pages, 0);
+
+	if (unlikely(!req->nr_pages))
+		return 0;
+
+	rcu_read_lock();
+	xas_for_each(&xas, page, last) {
+		if (xas_retry(&xas, page))
+			continue;
+
+		BUG_ON(PageCompound(page));
+		BUG_ON(page->mapping != mapping);
+
+		ret = afs_dir_check_page(dvnode, page, req->file_size);
+		if (ret < 0) {
+			afs_dir_dump(dvnode, req);
+			break;
+		}
+	}
+
+	rcu_read_unlock();
+	return ret;
 }
 
 /*
@@ -214,58 +282,57 @@ static struct afs_read *afs_read_dir(struct afs_vnode *dvnode, struct key *key)
 {
 	struct afs_read *req;
 	loff_t i_size;
-	int nr_pages, nr_inline, i, n;
-	int ret = -ENOMEM;
+	int nr_pages, i, n;
+	int ret;
+
+	_enter("");
 
-retry:
+	req = kzalloc(sizeof(*req), GFP_KERNEL);
+	if (!req)
+		return ERR_PTR(-ENOMEM);
+
+	refcount_set(&req->usage, 1);
+	req->vnode = dvnode;
+	req->key = key_get(key);
+	req->cleanup = afs_dir_read_cleanup;
+
+expand:
 	i_size = i_size_read(&dvnode->vfs_inode);
-	if (i_size < 2048)
-		return ERR_PTR(afs_bad(dvnode, afs_file_error_dir_small));
+	if (i_size < 2048) {
+		ret = afs_bad(dvnode, afs_file_error_dir_small);
+		goto error;
+	}
 	if (i_size > 2048 * 1024) {
 		trace_afs_file_error(dvnode, -EFBIG, afs_file_error_dir_big);
-		return ERR_PTR(-EFBIG);
+		ret = -EFBIG;
+		goto error;
 	}
 
 	_enter("%llu", i_size);
 
-	/* Get a request record to hold the page list.  We want to hold it
-	 * inline if we can, but we don't want to make an order 1 allocation.
-	 */
 	nr_pages = (i_size + PAGE_SIZE - 1) / PAGE_SIZE;
-	nr_inline = nr_pages;
-	if (nr_inline > (PAGE_SIZE - sizeof(*req)) / sizeof(struct page *))
-		nr_inline = 0;
 
-	req = kzalloc(struct_size(req, array, nr_inline), GFP_KERNEL);
-	if (!req)
-		return ERR_PTR(-ENOMEM);
-
-	refcount_set(&req->usage, 1);
-	req->key = key_get(key);
-	req->nr_pages = nr_pages;
 	req->actual_len = i_size; /* May change */
 	req->len = nr_pages * PAGE_SIZE; /* We can ask for more than there is */
 	req->data_version = dvnode->status.data_version; /* May change */
-	if (nr_inline > 0) {
-		req->pages = req->array;
-	} else {
-		req->pages = kcalloc(nr_pages, sizeof(struct page *),
-				     GFP_KERNEL);
-		if (!req->pages)
-			goto error;
-	}
+	iov_iter_xarray(&req->def_iter, READ, &dvnode->vfs_inode.i_mapping->i_pages,
+			0, i_size);
+	req->iter = &req->def_iter;
 
-	/* Get a list of all the pages that hold or will hold the directory
-	 * content.  We need to fill in any gaps that we might find where the
-	 * memory reclaimer has been at work.  If there are any gaps, we will
+	/* Fill in any gaps that we might find where the memory reclaimer has
+	 * been at work and pin all the pages.  If there are any gaps, we will
 	 * need to reread the entire directory contents.
 	 */
-	i = 0;
-	do {
+	i = req->nr_pages;
+	while (i < nr_pages) {
+		struct page *pages[8], *page;
+
 		n = find_get_pages_contig(dvnode->vfs_inode.i_mapping, i,
-					  req->nr_pages - i,
-					  req->pages + i);
-		_debug("find %u at %u/%u", n, i, req->nr_pages);
+					  min_t(unsigned int, nr_pages - i,
+						ARRAY_SIZE(pages)),
+					  pages);
+		_debug("find %u at %u/%u", n, i, nr_pages);
+
 		if (n == 0) {
 			gfp_t gfp = dvnode->vfs_inode.i_mapping->gfp_mask;
 
@@ -273,22 +340,24 @@ static struct afs_read *afs_read_dir(struct afs_vnode *dvnode, struct key *key)
 				afs_stat_v(dvnode, n_inval);
 
 			ret = -ENOMEM;
-			req->pages[i] = __page_cache_alloc(gfp);
-			if (!req->pages[i])
+			page = __page_cache_alloc(gfp);
+			if (!page)
 				goto error;
-			ret = add_to_page_cache_lru(req->pages[i],
+			ret = add_to_page_cache_lru(page,
 						    dvnode->vfs_inode.i_mapping,
 						    i, gfp);
 			if (ret < 0)
 				goto error;
 
-			attach_page_private(req->pages[i], (void *)1);
-			unlock_page(req->pages[i]);
+			attach_page_private(page, (void *)1);
+			unlock_page(page);
+			req->nr_pages++;
 			i++;
 		} else {
+			req->nr_pages += n;
 			i += n;
 		}
-	} while (i < req->nr_pages);
+	}
 
 	/* If we're going to reload, we need to lock all the pages to prevent
 	 * races.
@@ -312,12 +381,17 @@ static struct afs_read *afs_read_dir(struct afs_vnode *dvnode, struct key *key)
 
 		task_io_account_read(PAGE_SIZE * req->nr_pages);
 
-		if (req->len < req->file_size)
-			goto content_has_grown;
+		if (req->len < req->file_size) {
+			/* The content has grown, so we need to expand the
+			 * buffer.
+			 */
+			up_write(&dvnode->validate_lock);
+			goto expand;
+		}
 
 		/* Validate the data we just read. */
-		ret = -EIO;
-		if (!afs_dir_check_pages(dvnode, req))
+		ret = afs_dir_check(dvnode, req);
+		if (ret < 0)
 			goto error_unlock;
 
 		// TODO: Trim excess pages
@@ -335,11 +409,6 @@ static struct afs_read *afs_read_dir(struct afs_vnode *dvnode, struct key *key)
 	afs_put_read(req);
 	_leave(" = %d", ret);
 	return ERR_PTR(ret);
-
-content_has_grown:
-	up_write(&dvnode->validate_lock);
-	afs_put_read(req);
-	goto retry;
 }
 
 /*
@@ -449,6 +518,7 @@ static int afs_dir_iterate(struct inode *dir, struct dir_context *ctx,
 	struct afs_read *req;
 	struct page *page;
 	unsigned blkoff, limit;
+	void __rcu **slot;
 	int ret;
 
 	_enter("{%lu},%u,,", dir->i_ino, (unsigned)ctx->pos);
@@ -473,9 +543,15 @@ static int afs_dir_iterate(struct inode *dir, struct dir_context *ctx,
 		blkoff = ctx->pos & ~(sizeof(union afs_xdr_dir_block) - 1);
 
 		/* Fetch the appropriate page from the directory and re-add it
-		 * to the LRU.
+		 * to the LRU.  We have all the pages pinned with an extra ref.
 		 */
-		page = req->pages[blkoff / PAGE_SIZE];
+		rcu_read_lock();
+		page = NULL;
+		slot = radix_tree_lookup_slot(&dvnode->vfs_inode.i_mapping->i_pages,
+					      blkoff / PAGE_SIZE);
+		if (slot)
+			page = radix_tree_deref_slot(slot);
+		rcu_read_unlock();
 		if (!page) {
 			ret = afs_bad(dvnode, afs_file_error_dir_missing_page);
 			break;
diff --git a/fs/afs/file.c b/fs/afs/file.c
index d23192b3b933..f1bab69e99d4 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -184,21 +184,72 @@ int afs_release(struct inode *inode, struct file *file)
 	return ret;
 }
 
+/*
+ * Handle completion of a read operation.
+ */
+static void afs_file_read_done(struct afs_read *req)
+{
+	struct afs_vnode *vnode = req->vnode;
+	struct page *page;
+	pgoff_t index = req->pos >> PAGE_SHIFT;
+	pgoff_t last = index + req->nr_pages - 1;
+
+	XA_STATE(xas, &vnode->vfs_inode.i_mapping->i_pages, index);
+
+	if (iov_iter_count(req->iter) > 0) {
+		/* The read was short - clear the excess buffer. */
+		_debug("afterclear %zx %zx %llx/%llx",
+		       req->iter->iov_offset,
+		       iov_iter_count(req->iter),
+		       req->actual_len, req->len);
+		iov_iter_zero(iov_iter_count(req->iter), req->iter);
+	}
+
+	rcu_read_lock();
+	xas_for_each(&xas, page, last) {
+		page_endio(page, false, 0);
+		put_page(page);
+	}
+	rcu_read_unlock();
+
+	task_io_account_read(req->len);
+	req->cleanup = NULL;
+}
+
+/*
+ * Dispose of our locks and refs on the pages if the read failed.
+ */
+static void afs_file_read_cleanup(struct afs_read *req)
+{
+	struct page *page;
+	pgoff_t index = req->pos >> PAGE_SHIFT;
+	pgoff_t last = index + req->nr_pages - 1;
+
+	if (req->iter) {
+		XA_STATE(xas, &req->vnode->vfs_inode.i_mapping->i_pages, index);
+
+		_enter("%lu,%u,%zu", index, req->nr_pages, iov_iter_count(req->iter));
+
+		rcu_read_lock();
+		xas_for_each(&xas, page, last) {
+			BUG_ON(xa_is_value(page));
+			BUG_ON(PageCompound(page));
+
+			page_endio(page, false, req->error);
+			put_page(page);
+		}
+		rcu_read_unlock();
+	}
+}
+
 /*
  * Dispose of a ref to a read record.
  */
 void afs_put_read(struct afs_read *req)
 {
-	int i;
-
 	if (refcount_dec_and_test(&req->usage)) {
-		if (req->pages) {
-			for (i = 0; i < req->nr_pages; i++)
-				if (req->pages[i])
-					put_page(req->pages[i]);
-			if (req->pages != req->array)
-				kfree(req->pages);
-		}
+		if (req->cleanup)
+			req->cleanup(req);
 		key_put(req->key);
 		kfree(req);
 	}
@@ -216,6 +267,7 @@ static void afs_fetch_data_success(struct afs_operation *op)
 
 static void afs_fetch_data_put(struct afs_operation *op)
 {
+	op->fetch.req->error = op->error;
 	afs_put_read(op->fetch.req);
 }
 
@@ -255,12 +307,11 @@ int afs_fetch_data(struct afs_vnode *vnode, struct afs_read *req)
 /*
  * read page from file, directory or symlink, given a key to use
  */
-int afs_page_filler(void *data, struct page *page)
+static int afs_page_filler(struct key *key, struct page *page)
 {
 	struct inode *inode = page->mapping->host;
 	struct afs_vnode *vnode = AFS_FS_I(inode);
 	struct afs_read *req;
-	struct key *key = data;
 	int ret;
 
 	_enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
@@ -271,53 +322,52 @@ int afs_page_filler(void *data, struct page *page)
 	if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
 		goto error;
 
-	req = kzalloc(struct_size(req, array, 1), GFP_KERNEL);
+	req = kzalloc(sizeof(struct afs_read), GFP_KERNEL);
 	if (!req)
 		goto enomem;
 
-	/* We request a full page.  If the page is a partial one at the
-	 * end of the file, the server will return a short read and the
-	 * unmarshalling code will clear the unfilled space.
-	 */
 	refcount_set(&req->usage, 1);
-	req->key = key_get(key);
-	req->pos = (loff_t)page->index << PAGE_SHIFT;
-	req->len = PAGE_SIZE;
-	req->nr_pages = 1;
-	req->pages = req->array;
-	req->pages[0] = page;
+	req->vnode		= vnode;
+	req->key		= key_get(key);
+	req->pos		= (loff_t)page->index << PAGE_SHIFT;
+	req->len		= PAGE_SIZE;
+	req->nr_pages		= 1;
+	req->done		= afs_file_read_done;
+	req->cleanup		= afs_file_read_cleanup;
+
 	get_page(page);
+	iov_iter_xarray(&req->def_iter, READ, &page->mapping->i_pages,
+			req->pos, req->len);
+	req->iter = &req->def_iter;
 
-	/* read the contents of the file from the server into the
-	 * page */
 	ret = afs_fetch_data(vnode, req);
-	afs_put_read(req);
-
-	if (ret < 0) {
-		if (ret == -ENOENT) {
-			_debug("got NOENT from server"
-			       " - marking file deleted and stale");
-			set_bit(AFS_VNODE_DELETED, &vnode->flags);
-			ret = -ESTALE;
-		}
-
-		if (ret == -EINTR ||
-		    ret == -ENOMEM ||
-		    ret == -ERESTARTSYS ||
-		    ret == -EAGAIN)
-			goto error;
-		goto io_error;
-	}
-
-	SetPageUptodate(page);
-	unlock_page(page);
+	if (ret < 0)
+		goto fetch_error;
 
+	afs_put_read(req);
 	_leave(" = 0");
 	return 0;
 
-io_error:
-	SetPageError(page);
-	goto error;
+fetch_error:
+	switch (ret) {
+	case -EINTR:
+	case -ENOMEM:
+	case -ERESTARTSYS:
+	case -EAGAIN:
+		afs_put_read(req);
+		goto error;
+	case -ENOENT:
+		_debug("got NOENT from server - marking file deleted and stale");
+		set_bit(AFS_VNODE_DELETED, &vnode->flags);
+		ret = -ESTALE;
+		/* Fall through */
+	default:
+		page_endio(page, false, ret);
+		afs_put_read(req);
+		_leave(" = %d", ret);
+		return ret;
+	}
+
 enomem:
 	ret = -ENOMEM;
 error:
@@ -352,19 +402,6 @@ static int afs_readpage(struct file *file, struct page *page)
 	return ret;
 }
 
-/*
- * Make pages available as they're filled.
- */
-static void afs_readpages_page_done(struct afs_read *req)
-{
-	struct page *page = req->pages[req->index];
-
-	req->pages[req->index] = NULL;
-	SetPageUptodate(page);
-	unlock_page(page);
-	put_page(page);
-}
-
 /*
  * Read a contiguous set of pages.
  */
@@ -376,7 +413,7 @@ static int afs_readpages_one(struct file *file, struct address_space *mapping,
 	struct list_head *p;
 	struct page *first, *page;
 	pgoff_t index;
-	int ret, n, i;
+	int ret, n;
 
 	/* Count the number of contiguous pages at the front of the list.  Note
 	 * that the list goes prev-wards rather than next-wards.
@@ -392,21 +429,20 @@ static int afs_readpages_one(struct file *file, struct address_space *mapping,
 		n++;
 	}
 
-	req = kzalloc(struct_size(req, array, n), GFP_NOFS);
+	req = kzalloc(sizeof(struct afs_read), GFP_NOFS);
 	if (!req)
 		return -ENOMEM;
 
 	refcount_set(&req->usage, 1);
 	req->vnode = vnode;
 	req->key = key_get(afs_file_key(file));
-	req->page_done = afs_readpages_page_done;
+	req->done = afs_file_read_done;
+	req->cleanup = afs_file_read_cleanup;
 	req->pos = first->index;
 	req->pos <<= PAGE_SHIFT;
-	req->pages = req->array;
 
-	/* Transfer the pages to the request.  We add them in until one fails
-	 * to add to the LRU and then we stop (as that'll make a hole in the
-	 * contiguous run.
+	/* Add pages to the LRU until it fails.  We keep the pages ref'd and
+	 * locked until the read is complete.
 	 *
 	 * Note that it's possible for the file size to change whilst we're
 	 * doing this, but we rely on the server returning less than we asked
@@ -423,8 +459,7 @@ static int afs_readpages_one(struct file *file, struct address_space *mapping,
 			break;
 		}
 
-		req->pages[req->nr_pages++] = page;
-		req->len += PAGE_SIZE;
+		req->nr_pages++;
 	} while (req->nr_pages < n);
 
 	if (req->nr_pages == 0) {
@@ -432,30 +467,25 @@ static int afs_readpages_one(struct file *file, struct address_space *mapping,
 		return 0;
 	}
 
+	req->len = req->nr_pages * PAGE_SIZE;
+	iov_iter_xarray(&req->def_iter, READ, &file->f_mapping->i_pages,
+			req->pos, req->len);
+	req->iter = &req->def_iter;
+
 	ret = afs_fetch_data(vnode, req);
 	if (ret < 0)
 		goto error;
 
-	task_io_account_read(PAGE_SIZE * req->nr_pages);
 	afs_put_read(req);
 	return 0;
 
 error:
 	if (ret == -ENOENT) {
-		_debug("got NOENT from server"
-		       " - marking file deleted and stale");
+		_debug("got NOENT from server - marking file deleted and stale");
 		set_bit(AFS_VNODE_DELETED, &vnode->flags);
 		ret = -ESTALE;
 	}
 
-	for (i = 0; i < req->nr_pages; i++) {
-		page = req->pages[i];
-		if (page) {
-			SetPageError(page);
-			unlock_page(page);
-		}
-	}
-
 	afs_put_read(req);
 	return ret;
 }
diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c
index 4a57c6c6f12b..897b37301851 100644
--- a/fs/afs/fsclient.c
+++ b/fs/afs/fsclient.c
@@ -302,7 +302,6 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call)
 	struct afs_vnode_param *vp = &op->file[0];
 	struct afs_read *req = op->fetch.req;
 	const __be32 *bp;
-	unsigned int size;
 	int ret;
 
 	_enter("{%u,%zu,%zu/%llu}",
@@ -312,8 +311,6 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call)
 	switch (call->unmarshall) {
 	case 0:
 		req->actual_len = 0;
-		req->index = 0;
-		req->offset = req->pos & (PAGE_SIZE - 1);
 		call->unmarshall++;
 		if (call->operation_ID == FSFETCHDATA64) {
 			afs_extract_to_tmp64(call);
@@ -323,7 +320,10 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call)
 		}
 		fallthrough;
 
-		/* extract the returned data length */
+		/* Extract the returned data length into
+		 * ->actual_len.  This may indicate more or less data than was
+		 * requested will be returned.
+		 */
 	case 1:
 		_debug("extract data length");
 		ret = afs_extract_data(call, true);
@@ -332,45 +332,25 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call)
 
 		req->actual_len = be64_to_cpu(call->tmp64);
 		_debug("DATA length: %llu", req->actual_len);
-		req->remain = min(req->len, req->actual_len);
-		if (req->remain == 0)
+
+		if (req->actual_len == 0)
 			goto no_more_data;
 
+		call->iter = req->iter;
+		call->iov_len = min(req->actual_len, req->len);
 		call->unmarshall++;
-
-	begin_page:
-		ASSERTCMP(req->index, <, req->nr_pages);
-		if (req->remain > PAGE_SIZE - req->offset)
-			size = PAGE_SIZE - req->offset;
-		else
-			size = req->remain;
-		call->iov_len = size;
-		call->bvec[0].bv_len = size;
-		call->bvec[0].bv_offset = req->offset;
-		call->bvec[0].bv_page = req->pages[req->index];
-		iov_iter_bvec(&call->def_iter, READ, call->bvec, 1, size);
-		ASSERTCMP(size, <=, PAGE_SIZE);
 		fallthrough;
 
 		/* extract the returned data */
 	case 2:
 		_debug("extract data %zu/%llu",
-		       iov_iter_count(call->iter), req->remain);
+		       iov_iter_count(call->iter), req->actual_len);
 
 		ret = afs_extract_data(call, true);
 		if (ret < 0)
 			return ret;
-		req->remain -= call->bvec[0].bv_len;
-		req->offset += call->bvec[0].bv_len;
-		ASSERTCMP(req->offset, <=, PAGE_SIZE);
-		if (req->offset == PAGE_SIZE) {
-			req->offset = 0;
-			req->index++;
-			if (req->remain > 0)
-				goto begin_page;
-		}
 
-		ASSERTCMP(req->remain, ==, 0);
+		call->iter = &call->def_iter;
 		if (req->actual_len <= req->len)
 			goto no_more_data;
 
@@ -412,16 +392,8 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call)
 		break;
 	}
 
-	for (; req->index < req->nr_pages; req->index++) {
-		if (req->offset < PAGE_SIZE)
-			zero_user_segment(req->pages[req->index],
-					  req->offset, PAGE_SIZE);
-		req->offset = 0;
-	}
-
-	if (req->page_done)
-		for (req->index = 0; req->index < req->nr_pages; req->index++)
-			req->page_done(req);
+	if (req->done)
+		req->done(req);
 
 	_leave(" = 0 [done]");
 	return 0;
@@ -496,6 +468,8 @@ void afs_fs_fetch_data(struct afs_operation *op)
 	if (!call)
 		return afs_op_nomem(op);
 
+	req->call_debug_id = call->debug_id;
+
 	/* marshall the parameters */
 	bp = call->request;
 	bp[0] = htonl(FSFETCHDATA);
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 1badc7ed0487..6f1e6badf391 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -31,6 +31,7 @@
 
 struct pagevec;
 struct afs_call;
+struct afs_vnode;
 
 /*
  * Partial file-locking emulation mode.  (The problem being that AFS3 only
@@ -203,18 +204,18 @@ struct afs_read {
 	loff_t			pos;		/* Where to start reading */
 	loff_t			len;		/* How much we're asking for */
 	loff_t			actual_len;	/* How much we're actually getting */
-	loff_t			remain;		/* Amount remaining */
 	loff_t			file_size;	/* File size returned by server */
 	struct key		*key;		/* The key to use to reissue the read */
+	struct afs_vnode	*vnode;		/* The file being read into. */
 	afs_dataversion_t	data_version;	/* Version number returned by server */
 	refcount_t		usage;
-	unsigned int		index;		/* Which page we're reading into */
+	unsigned int		call_debug_id;
 	unsigned int		nr_pages;
-	unsigned int		offset;		/* offset into current page */
-	struct afs_vnode	*vnode;
-	void (*page_done)(struct afs_read *);
-	struct page		**pages;
-	struct page		*array[];
+	int			error;
+	void (*done)(struct afs_read *);
+	void (*cleanup)(struct afs_read *);
+	struct iov_iter		*iter;		/* Iterator representing the buffer */
+	struct iov_iter		def_iter;	/* Default iterator */
 };
 
 /*
@@ -1048,7 +1049,6 @@ extern void afs_put_wb_key(struct afs_wb_key *);
 extern int afs_open(struct inode *, struct file *);
 extern int afs_release(struct inode *, struct file *);
 extern int afs_fetch_data(struct afs_vnode *, struct afs_read *);
-extern int afs_page_filler(void *, struct page *);
 extern void afs_put_read(struct afs_read *);
 
 static inline struct afs_read *afs_get_read(struct afs_read *req)
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 7eba0d3201ba..e78a9bc3b02d 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -22,6 +22,16 @@ int afs_set_page_dirty(struct page *page)
 	return __set_page_dirty_nobuffers(page);
 }
 
+/*
+ * Handle completion of a read operation to fill a page.
+ */
+static void afs_fill_hole(struct afs_read *req)
+{
+	if (iov_iter_count(req->iter) > 0)
+		/* The read was short - clear the excess buffer. */
+		iov_iter_zero(iov_iter_count(req->iter), req->iter);
+}
+
 /*
  * partly or wholly fill a page that's under preparation for writing
  */
@@ -45,18 +55,19 @@ static int afs_fill_page(struct file *file,
 		return 0;
 	}
 
-	req = kzalloc(struct_size(req, array, 1), GFP_KERNEL);
+	req = kzalloc(sizeof(struct afs_read), GFP_KERNEL);
 	if (!req)
 		return -ENOMEM;
 
 	refcount_set(&req->usage, 1);
-	req->key = key_get(afs_file_key(file));
-	req->pos = pos;
-	req->len = len;
-	req->nr_pages = 1;
-	req->pages = req->array;
-	req->pages[0] = page;
-	get_page(page);
+	req->vnode	= vnode;
+	req->done	= afs_fill_hole;
+	req->key	= key_get(afs_file_key(file));
+	req->pos	= pos;
+	req->len	= len;
+	req->nr_pages	= 1;
+	req->iter	= &req->def_iter;
+	iov_iter_xarray(&req->def_iter, READ, &file->f_mapping->i_pages, pos, len);
 
 	ret = afs_fetch_data(vnode, req);
 	afs_put_read(req);
diff --git a/fs/afs/yfsclient.c b/fs/afs/yfsclient.c
index 6c45d32da13c..abcec145db4b 100644
--- a/fs/afs/yfsclient.c
+++ b/fs/afs/yfsclient.c
@@ -360,7 +360,6 @@ static int yfs_deliver_fs_fetch_data64(struct afs_call *call)
 	struct afs_vnode_param *vp = &op->file[0];
 	struct afs_read *req = op->fetch.req;
 	const __be32 *bp;
-	unsigned int size;
 	int ret;
 
 	_enter("{%u,%zu, %zu/%llu}",
@@ -370,13 +369,14 @@ static int yfs_deliver_fs_fetch_data64(struct afs_call *call)
 	switch (call->unmarshall) {
 	case 0:
 		req->actual_len = 0;
-		req->index = 0;
-		req->offset = req->pos & (PAGE_SIZE - 1);
 		afs_extract_to_tmp64(call);
 		call->unmarshall++;
 		fallthrough;
 
-		/* extract the returned data length */
+		/* Extract the returned data length into ->actual_len.  This
+		 * may indicate more or less data than was requested will be
+		 * returned.
+		 */
 	case 1:
 		_debug("extract data length");
 		ret = afs_extract_data(call, true);
@@ -385,45 +385,25 @@ static int yfs_deliver_fs_fetch_data64(struct afs_call *call)
 
 		req->actual_len = be64_to_cpu(call->tmp64);
 		_debug("DATA length: %llu", req->actual_len);
-		req->remain = min(req->len, req->actual_len);
-		if (req->remain == 0)
+
+		if (req->actual_len == 0)
 			goto no_more_data;
 
+		call->iter = req->iter;
+		call->iov_len = min(req->actual_len, req->len);
 		call->unmarshall++;
-
-	begin_page:
-		ASSERTCMP(req->index, <, req->nr_pages);
-		if (req->remain > PAGE_SIZE - req->offset)
-			size = PAGE_SIZE - req->offset;
-		else
-			size = req->remain;
-		call->iov_len = size;
-		call->bvec[0].bv_len = size;
-		call->bvec[0].bv_offset = req->offset;
-		call->bvec[0].bv_page = req->pages[req->index];
-		iov_iter_bvec(&call->def_iter, READ, call->bvec, 1, size);
-		ASSERTCMP(size, <=, PAGE_SIZE);
 		fallthrough;
 
 		/* extract the returned data */
 	case 2:
 		_debug("extract data %zu/%llu",
-		       iov_iter_count(call->iter), req->remain);
+		       iov_iter_count(call->iter), req->actual_len);
 
 		ret = afs_extract_data(call, true);
 		if (ret < 0)
 			return ret;
-		req->remain -= call->bvec[0].bv_len;
-		req->offset += call->bvec[0].bv_len;
-		ASSERTCMP(req->offset, <=, PAGE_SIZE);
-		if (req->offset == PAGE_SIZE) {
-			req->offset = 0;
-			req->index++;
-			if (req->remain > 0)
-				goto begin_page;
-		}
 
-		ASSERTCMP(req->remain, ==, 0);
+		call->iter = &call->def_iter;
 		if (req->actual_len <= req->len)
 			goto no_more_data;
 
@@ -469,16 +449,8 @@ static int yfs_deliver_fs_fetch_data64(struct afs_call *call)
 		break;
 	}
 
-	for (; req->index < req->nr_pages; req->index++) {
-		if (req->offset < PAGE_SIZE)
-			zero_user_segment(req->pages[req->index],
-					  req->offset, PAGE_SIZE);
-		req->offset = 0;
-	}
-
-	if (req->page_done)
-		for (req->index = 0; req->index < req->nr_pages; req->index++)
-			req->page_done(req);
+	if (req->done)
+		req->done(req);
 
 	_leave(" = 0 [done]");
 	return 0;
@@ -518,6 +490,8 @@ void yfs_fs_fetch_data(struct afs_operation *op)
 	if (!call)
 		return afs_op_nomem(op);
 
+	req->call_debug_id = call->debug_id;
+
 	/* marshall the parameters */
 	bp = call->request;
 	bp = xdr_encode_u32(bp, YFSFETCHDATA64);



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 19/32] afs: Use ITER_XARRAY for writing
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (17 preceding siblings ...)
  2021-01-25 21:34 ` [PATCH 18/32] afs: Set up the iov_iter before calling afs_extract_data() David Howells
@ 2021-01-25 21:34 ` David Howells
  2021-01-25 21:34 ` [PATCH 20/32] afs: Wait on PG_fscache before modifying/releasing a page David Howells
                   ` (12 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:34 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Use a single ITER_XARRAY iterator to describe the portion of a file to be
transmitted to the server rather than generating a series of small
ITER_BVEC iterators on the fly.  This will make it easier to implement AIO
in afs.

In theory we could maybe use one giant ITER_BVEC, but that means
potentially allocating a huge array of bio_vec structs (max 256 per page)
when in fact the pagecache already has a structure listing all the relevant
pages (radix_tree/xarray) that can be walked over.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/fsclient.c          |   50 +++++++++------------
 fs/afs/internal.h          |   15 +++---
 fs/afs/rxrpc.c             |  103 ++++++--------------------------------------
 fs/afs/write.c             |  100 ++++++++++++++++++++++++-------------------
 fs/afs/yfsclient.c         |   25 +++--------
 include/trace/events/afs.h |   51 ++++++++--------------
 6 files changed, 126 insertions(+), 218 deletions(-)

diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c
index 897b37301851..31e6b3635541 100644
--- a/fs/afs/fsclient.c
+++ b/fs/afs/fsclient.c
@@ -1055,8 +1055,7 @@ static const struct afs_call_type afs_RXFSStoreData64 = {
 /*
  * store a set of pages to a very large file
  */
-static void afs_fs_store_data64(struct afs_operation *op,
-				loff_t pos, loff_t size, loff_t i_size)
+static void afs_fs_store_data64(struct afs_operation *op)
 {
 	struct afs_vnode_param *vp = &op->file[0];
 	struct afs_call *call;
@@ -1071,7 +1070,7 @@ static void afs_fs_store_data64(struct afs_operation *op,
 	if (!call)
 		return afs_op_nomem(op);
 
-	call->send_pages = true;
+	call->write_iter = op->store.write_iter;
 
 	/* marshall the parameters */
 	bp = call->request;
@@ -1087,47 +1086,38 @@ static void afs_fs_store_data64(struct afs_operation *op,
 	*bp++ = 0; /* unix mode */
 	*bp++ = 0; /* segment size */
 
-	*bp++ = htonl(upper_32_bits(pos));
-	*bp++ = htonl(lower_32_bits(pos));
-	*bp++ = htonl(upper_32_bits(size));
-	*bp++ = htonl(lower_32_bits(size));
-	*bp++ = htonl(upper_32_bits(i_size));
-	*bp++ = htonl(lower_32_bits(i_size));
+	*bp++ = htonl(upper_32_bits(op->store.pos));
+	*bp++ = htonl(lower_32_bits(op->store.pos));
+	*bp++ = htonl(upper_32_bits(op->store.size));
+	*bp++ = htonl(lower_32_bits(op->store.size));
+	*bp++ = htonl(upper_32_bits(op->store.i_size));
+	*bp++ = htonl(lower_32_bits(op->store.i_size));
 
 	trace_afs_make_fs_call(call, &vp->fid);
 	afs_make_op_call(op, call, GFP_NOFS);
 }
 
 /*
- * store a set of pages
+ * Write data to a file on the server.
  */
 void afs_fs_store_data(struct afs_operation *op)
 {
 	struct afs_vnode_param *vp = &op->file[0];
 	struct afs_call *call;
-	loff_t size, pos, i_size;
 	__be32 *bp;
 
 	_enter(",%x,{%llx:%llu},,",
 	       key_serial(op->key), vp->fid.vid, vp->fid.vnode);
 
-	size = (loff_t)op->store.last_to - (loff_t)op->store.first_offset;
-	if (op->store.first != op->store.last)
-		size += (loff_t)(op->store.last - op->store.first) << PAGE_SHIFT;
-	pos = (loff_t)op->store.first << PAGE_SHIFT;
-	pos += op->store.first_offset;
-
-	i_size = i_size_read(&vp->vnode->vfs_inode);
-	if (pos + size > i_size)
-		i_size = size + pos;
-
 	_debug("size %llx, at %llx, i_size %llx",
-	       (unsigned long long) size, (unsigned long long) pos,
-	       (unsigned long long) i_size);
+	       (unsigned long long)op->store.size,
+	       (unsigned long long)op->store.pos,
+	       (unsigned long long)op->store.i_size);
 
-	if (upper_32_bits(pos) || upper_32_bits(i_size) || upper_32_bits(size) ||
-	    upper_32_bits(pos + size))
-		return afs_fs_store_data64(op, pos, size, i_size);
+	if (upper_32_bits(op->store.pos) ||
+	    upper_32_bits(op->store.size) ||
+	    upper_32_bits(op->store.i_size))
+		return afs_fs_store_data64(op);
 
 	call = afs_alloc_flat_call(op->net, &afs_RXFSStoreData,
 				   (4 + 6 + 3) * 4,
@@ -1135,7 +1125,7 @@ void afs_fs_store_data(struct afs_operation *op)
 	if (!call)
 		return afs_op_nomem(op);
 
-	call->send_pages = true;
+	call->write_iter = op->store.write_iter;
 
 	/* marshall the parameters */
 	bp = call->request;
@@ -1151,9 +1141,9 @@ void afs_fs_store_data(struct afs_operation *op)
 	*bp++ = 0; /* unix mode */
 	*bp++ = 0; /* segment size */
 
-	*bp++ = htonl(lower_32_bits(pos));
-	*bp++ = htonl(lower_32_bits(size));
-	*bp++ = htonl(lower_32_bits(i_size));
+	*bp++ = htonl(lower_32_bits(op->store.pos));
+	*bp++ = htonl(lower_32_bits(op->store.size));
+	*bp++ = htonl(lower_32_bits(op->store.i_size));
 
 	trace_afs_make_fs_call(call, &vp->fid);
 	afs_make_op_call(op, call, GFP_NOFS);
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 6f1e6badf391..d4163f9babfd 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -107,6 +107,7 @@ struct afs_call {
 	void			*request;	/* request data (first part) */
 	size_t			iov_len;	/* Size of *iter to be used */
 	struct iov_iter		def_iter;	/* Default buffer/data iterator */
+	struct iov_iter		*write_iter;	/* Iterator defining write to be made */
 	struct iov_iter		*iter;		/* Iterator currently in use */
 	union {	/* Convenience for ->def_iter */
 		struct kvec	kvec[1];
@@ -133,7 +134,6 @@ struct afs_call {
 	unsigned char		unmarshall;	/* unmarshalling phase */
 	unsigned char		addr_ix;	/* Address in ->alist */
 	bool			drop_ref;	/* T if need to drop ref for incoming call */
-	bool			send_pages;	/* T if data from mapping should be sent */
 	bool			need_attention;	/* T if RxRPC poked us */
 	bool			async;		/* T if asynchronous */
 	bool			upgrade;	/* T to request service upgrade */
@@ -811,12 +811,13 @@ struct afs_operation {
 			afs_lock_type_t type;
 		} lock;
 		struct {
-			struct address_space *mapping;	/* Pages being written from */
-			pgoff_t		first;		/* first page in mapping to deal with */
-			pgoff_t		last;		/* last page in mapping to deal with */
-			unsigned	first_offset;	/* offset into mapping[first] */
-			unsigned	last_to;	/* amount of mapping[last] */
-			bool		laundering;	/* Laundering page, PG_writeback not set */
+			struct iov_iter	*write_iter;
+			loff_t	pos;
+			loff_t	size;
+			loff_t	i_size;
+			pgoff_t	first;		/* first page in mapping to deal with */
+			pgoff_t	last;		/* last page in mapping to deal with */
+			bool	laundering;	/* Laundering page, PG_writeback not set */
 		} store;
 		struct {
 			struct iattr	*attr;
diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index ae68576f822f..23a1a92d64bb 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -271,40 +271,6 @@ void afs_flat_call_destructor(struct afs_call *call)
 	call->buffer = NULL;
 }
 
-#define AFS_BVEC_MAX 8
-
-/*
- * Load the given bvec with the next few pages.
- */
-static void afs_load_bvec(struct afs_call *call, struct msghdr *msg,
-			  struct bio_vec *bv, pgoff_t first, pgoff_t last,
-			  unsigned offset)
-{
-	struct afs_operation *op = call->op;
-	struct page *pages[AFS_BVEC_MAX];
-	unsigned int nr, n, i, to, bytes = 0;
-
-	nr = min_t(pgoff_t, last - first + 1, AFS_BVEC_MAX);
-	n = find_get_pages_contig(op->store.mapping, first, nr, pages);
-	ASSERTCMP(n, ==, nr);
-
-	msg->msg_flags |= MSG_MORE;
-	for (i = 0; i < nr; i++) {
-		to = PAGE_SIZE;
-		if (first + i >= last) {
-			to = op->store.last_to;
-			msg->msg_flags &= ~MSG_MORE;
-		}
-		bv[i].bv_page = pages[i];
-		bv[i].bv_len = to - offset;
-		bv[i].bv_offset = offset;
-		bytes += to - offset;
-		offset = 0;
-	}
-
-	iov_iter_bvec(&msg->msg_iter, WRITE, bv, nr, bytes);
-}
-
 /*
  * Advance the AFS call state when the RxRPC call ends the transmit phase.
  */
@@ -317,42 +283,6 @@ static void afs_notify_end_request_tx(struct sock *sock,
 	afs_set_call_state(call, AFS_CALL_CL_REQUESTING, AFS_CALL_CL_AWAIT_REPLY);
 }
 
-/*
- * attach the data from a bunch of pages on an inode to a call
- */
-static int afs_send_pages(struct afs_call *call, struct msghdr *msg)
-{
-	struct afs_operation *op = call->op;
-	struct bio_vec bv[AFS_BVEC_MAX];
-	unsigned int bytes, nr, loop, offset;
-	pgoff_t first = op->store.first, last = op->store.last;
-	int ret;
-
-	offset = op->store.first_offset;
-	op->store.first_offset = 0;
-
-	do {
-		afs_load_bvec(call, msg, bv, first, last, offset);
-		trace_afs_send_pages(call, msg, first, last, offset);
-
-		offset = 0;
-		bytes = msg->msg_iter.count;
-		nr = msg->msg_iter.nr_segs;
-
-		ret = rxrpc_kernel_send_data(op->net->socket, call->rxcall, msg,
-					     bytes, afs_notify_end_request_tx);
-		for (loop = 0; loop < nr; loop++)
-			put_page(bv[loop].bv_page);
-		if (ret < 0)
-			break;
-
-		first += nr;
-	} while (first <= last);
-
-	trace_afs_sent_pages(call, op->store.first, last, first, ret);
-	return ret;
-}
-
 /*
  * Initiate a call and synchronously queue up the parameters for dispatch.  Any
  * error is stored into the call struct, which the caller must check for.
@@ -384,21 +314,8 @@ void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp)
 	 * after the initial fixed part.
 	 */
 	tx_total_len = call->request_size;
-	if (call->send_pages) {
-		struct afs_operation *op = call->op;
-
-		if (op->store.last == op->store.first) {
-			tx_total_len += op->store.last_to - op->store.first_offset;
-		} else {
-			/* It looks mathematically like you should be able to
-			 * combine the following lines with the ones above, but
-			 * unsigned arithmetic is fun when it wraps...
-			 */
-			tx_total_len += PAGE_SIZE - op->store.first_offset;
-			tx_total_len += op->store.last_to;
-			tx_total_len += (op->store.last - op->store.first - 1) * PAGE_SIZE;
-		}
-	}
+	if (call->write_iter)
+		tx_total_len += iov_iter_count(call->write_iter);
 
 	/* If the call is going to be asynchronous, we need an extra ref for
 	 * the call to hold itself so the caller need not hang on to its ref.
@@ -440,7 +357,7 @@ void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp)
 	iov_iter_kvec(&msg.msg_iter, WRITE, iov, 1, call->request_size);
 	msg.msg_control		= NULL;
 	msg.msg_controllen	= 0;
-	msg.msg_flags		= MSG_WAITALL | (call->send_pages ? MSG_MORE : 0);
+	msg.msg_flags		= MSG_WAITALL | (call->write_iter ? MSG_MORE : 0);
 
 	ret = rxrpc_kernel_send_data(call->net->socket, rxcall,
 				     &msg, call->request_size,
@@ -448,8 +365,18 @@ void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp)
 	if (ret < 0)
 		goto error_do_abort;
 
-	if (call->send_pages) {
-		ret = afs_send_pages(call, &msg);
+	if (call->write_iter) {
+		msg.msg_iter = *call->write_iter;
+		msg.msg_flags &= ~MSG_MORE;
+		trace_afs_send_data(call, &msg);
+
+		ret = rxrpc_kernel_send_data(call->net->socket,
+					     call->rxcall, &msg,
+					     iov_iter_count(&msg.msg_iter),
+					     afs_notify_end_request_tx);
+		*call->write_iter = msg.msg_iter;
+
+		trace_afs_sent_data(call, &msg, ret);
 		if (ret < 0)
 			goto error_do_abort;
 	}
diff --git a/fs/afs/write.c b/fs/afs/write.c
index e78a9bc3b02d..dd4dc1c868b5 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -325,36 +325,27 @@ static void afs_redirty_pages(struct writeback_control *wbc,
 /*
  * completion of write to server
  */
-static void afs_pages_written_back(struct afs_vnode *vnode,
-				   pgoff_t first, pgoff_t last)
+static void afs_pages_written_back(struct afs_vnode *vnode, pgoff_t start, pgoff_t last)
 {
-	struct pagevec pv;
-	unsigned count, loop;
+	struct address_space *mapping = vnode->vfs_inode.i_mapping;
+	struct page *page;
+
+	XA_STATE(xas, &mapping->i_pages, start);
 
 	_enter("{%llx:%llu},{%lx-%lx}",
-	       vnode->fid.vid, vnode->fid.vnode, first, last);
+	       vnode->fid.vid, vnode->fid.vnode, start, last);
 
-	pagevec_init(&pv);
+	rcu_read_lock();
 
-	do {
-		_debug("done %lx-%lx", first, last);
+	xas_for_each(&xas, page, last) {
+		ASSERT(PageWriteback(page));
 
-		count = last - first + 1;
-		if (count > PAGEVEC_SIZE)
-			count = PAGEVEC_SIZE;
-		pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
-					      first, count, pv.pages);
-		ASSERTCMP(pv.nr, ==, count);
+		detach_page_private(page);
+		trace_afs_page_dirty(vnode, tracepoint_string("clear"), page);
+		page_endio(page, true, 0);
+	}
 
-		for (loop = 0; loop < count; loop++) {
-			detach_page_private(pv.pages[loop]);
-			trace_afs_page_dirty(vnode, tracepoint_string("clear"),
-					     pv.pages[loop]);
-			end_page_writeback(pv.pages[loop]);
-		}
-		first += count;
-		__pagevec_release(&pv);
-	} while (first <= last);
+	rcu_read_unlock();
 
 	afs_prune_wb_keys(vnode);
 	_leave("");
@@ -411,9 +402,7 @@ static void afs_store_data_success(struct afs_operation *op)
 		if (!op->store.laundering)
 			afs_pages_written_back(vnode, op->store.first, op->store.last);
 		afs_stat_v(vnode, n_stores);
-		atomic_long_add((op->store.last * PAGE_SIZE + op->store.last_to) -
-				(op->store.first * PAGE_SIZE + op->store.first_offset),
-				&afs_v2net(vnode)->n_store_bytes);
+		atomic_long_add(op->store.size, &afs_v2net(vnode)->n_store_bytes);
 	}
 }
 
@@ -426,21 +415,21 @@ static const struct afs_operation_ops afs_store_data_operation = {
 /*
  * write to a file
  */
-static int afs_store_data(struct address_space *mapping,
-			  pgoff_t first, pgoff_t last,
-			  unsigned offset, unsigned to, bool laundering)
+static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter,
+			  loff_t pos, pgoff_t first, pgoff_t last,
+			  bool laundering)
 {
-	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 	struct afs_operation *op;
 	struct afs_wb_key *wbk = NULL;
-	int ret;
+	loff_t size = iov_iter_count(iter), i_size;
+	int ret = -ENOKEY;
 
-	_enter("%s{%llx:%llu.%u},%lx,%lx,%x,%x",
+	_enter("%s{%llx:%llu.%u},%llx,%llx",
 	       vnode->volume->name,
 	       vnode->fid.vid,
 	       vnode->fid.vnode,
 	       vnode->fid.unique,
-	       first, last, offset, to);
+	       size, pos);
 
 	ret = afs_get_writeback_key(vnode, &wbk);
 	if (ret) {
@@ -454,13 +443,16 @@ static int afs_store_data(struct address_space *mapping,
 		return -ENOMEM;
 	}
 
+	i_size = i_size_read(&vnode->vfs_inode);
+
 	afs_op_set_vnode(op, 0, vnode);
 	op->file[0].dv_delta = 1;
-	op->store.mapping = mapping;
+	op->store.write_iter = iter;
+	op->store.pos = pos;
 	op->store.first = first;
 	op->store.last = last;
-	op->store.first_offset = offset;
-	op->store.last_to = to;
+	op->store.size = size;
+	op->store.i_size = max(pos + size, i_size);
 	op->store.laundering = laundering;
 	op->mtime = vnode->vfs_inode.i_mtime;
 	op->flags |= AFS_OPERATION_UNINTR;
@@ -503,11 +495,12 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
 					   pgoff_t final_page)
 {
 	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
+	struct iov_iter iter;
 	struct page *pages[8], *page;
 	unsigned long count, priv;
 	unsigned n, offset, to, f, t;
 	pgoff_t start, first, last;
-	loff_t i_size, end;
+	loff_t i_size, pos, end;
 	int loop, ret;
 
 	_enter(",%lx", primary_page->index);
@@ -604,15 +597,28 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
 
 	first = primary_page->index;
 	last = first + count - 1;
+	_debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
 
-	end = (loff_t)last * PAGE_SIZE + to;
-	i_size = i_size_read(&vnode->vfs_inode);
+	pos = first;
+	pos <<= PAGE_SHIFT;
+	pos += offset;
+	end = last;
+	end <<= PAGE_SHIFT;
+	end += to;
 
-	_debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
+	/* Trim the actual write down to the EOF */
+	i_size = i_size_read(&vnode->vfs_inode);
 	if (end > i_size)
-		to = i_size & ~PAGE_MASK;
+		end = i_size;
+
+	if (pos < i_size) {
+		iov_iter_xarray(&iter, WRITE, &mapping->i_pages, pos, end - pos);
+		ret = afs_store_data(vnode, &iter, pos, first, last, false);
+	} else {
+		/* The dirty region was entirely beyond the EOF. */
+		ret = 0;
+	}
 
-	ret = afs_store_data(mapping, first, last, offset, to, false);
 	switch (ret) {
 	case 0:
 		ret = count;
@@ -913,6 +919,8 @@ int afs_launder_page(struct page *page)
 {
 	struct address_space *mapping = page->mapping;
 	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
+	struct iov_iter iter;
+	struct bio_vec bv[1];
 	unsigned long priv;
 	unsigned int f, t;
 	int ret = 0;
@@ -928,8 +936,14 @@ int afs_launder_page(struct page *page)
 			t = afs_page_dirty_to(page, priv);
 		}
 
+		bv[0].bv_page = page;
+		bv[0].bv_offset = f;
+		bv[0].bv_len = t - f;
+		iov_iter_bvec(&iter, WRITE, bv, 1, bv[0].bv_len);
+
 		trace_afs_page_dirty(vnode, tracepoint_string("launder"), page);
-		ret = afs_store_data(mapping, page->index, page->index, t, f, true);
+		ret = afs_store_data(vnode, &iter, (loff_t)page->index << PAGE_SHIFT,
+				     page->index, page->index, true);
 	}
 
 	detach_page_private(page);
diff --git a/fs/afs/yfsclient.c b/fs/afs/yfsclient.c
index abcec145db4b..363d6dd276c0 100644
--- a/fs/afs/yfsclient.c
+++ b/fs/afs/yfsclient.c
@@ -1078,25 +1078,15 @@ void yfs_fs_store_data(struct afs_operation *op)
 {
 	struct afs_vnode_param *vp = &op->file[0];
 	struct afs_call *call;
-	loff_t size, pos, i_size;
 	__be32 *bp;
 
 	_enter(",%x,{%llx:%llu},,",
 	       key_serial(op->key), vp->fid.vid, vp->fid.vnode);
 
-	size = (loff_t)op->store.last_to - (loff_t)op->store.first_offset;
-	if (op->store.first != op->store.last)
-		size += (loff_t)(op->store.last - op->store.first) << PAGE_SHIFT;
-	pos = (loff_t)op->store.first << PAGE_SHIFT;
-	pos += op->store.first_offset;
-
-	i_size = i_size_read(&vp->vnode->vfs_inode);
-	if (pos + size > i_size)
-		i_size = size + pos;
-
 	_debug("size %llx, at %llx, i_size %llx",
-	       (unsigned long long)size, (unsigned long long)pos,
-	       (unsigned long long)i_size);
+	       (unsigned long long)op->store.size,
+	       (unsigned long long)op->store.pos,
+	       (unsigned long long)op->store.i_size);
 
 	call = afs_alloc_flat_call(op->net, &yfs_RXYFSStoreData64,
 				   sizeof(__be32) +
@@ -1109,8 +1099,7 @@ void yfs_fs_store_data(struct afs_operation *op)
 	if (!call)
 		return afs_op_nomem(op);
 
-	call->key = op->key;
-	call->send_pages = true;
+	call->write_iter = op->store.write_iter;
 
 	/* marshall the parameters */
 	bp = call->request;
@@ -1118,9 +1107,9 @@ void yfs_fs_store_data(struct afs_operation *op)
 	bp = xdr_encode_u32(bp, 0); /* RPC flags */
 	bp = xdr_encode_YFSFid(bp, &vp->fid);
 	bp = xdr_encode_YFSStoreStatus_mtime(bp, &op->mtime);
-	bp = xdr_encode_u64(bp, pos);
-	bp = xdr_encode_u64(bp, size);
-	bp = xdr_encode_u64(bp, i_size);
+	bp = xdr_encode_u64(bp, op->store.pos);
+	bp = xdr_encode_u64(bp, op->store.size);
+	bp = xdr_encode_u64(bp, op->store.i_size);
 	yfs_check_req(call, bp);
 
 	trace_afs_make_fs_call(call, &vp->fid);
diff --git a/include/trace/events/afs.h b/include/trace/events/afs.h
index 9203cf6a8c53..3ccf591b2374 100644
--- a/include/trace/events/afs.h
+++ b/include/trace/events/afs.h
@@ -886,65 +886,52 @@ TRACE_EVENT(afs_call_done,
 		      __entry->rx_call)
 	    );
 
-TRACE_EVENT(afs_send_pages,
-	    TP_PROTO(struct afs_call *call, struct msghdr *msg,
-		     pgoff_t first, pgoff_t last, unsigned int offset),
+TRACE_EVENT(afs_send_data,
+	    TP_PROTO(struct afs_call *call, struct msghdr *msg),
 
-	    TP_ARGS(call, msg, first, last, offset),
+	    TP_ARGS(call, msg),
 
 	    TP_STRUCT__entry(
 		    __field(unsigned int,		call		)
-		    __field(pgoff_t,			first		)
-		    __field(pgoff_t,			last		)
-		    __field(unsigned int,		nr		)
-		    __field(unsigned int,		bytes		)
-		    __field(unsigned int,		offset		)
 		    __field(unsigned int,		flags		)
+		    __field(loff_t,			offset		)
+		    __field(loff_t,			count		)
 			     ),
 
 	    TP_fast_assign(
 		    __entry->call = call->debug_id;
-		    __entry->first = first;
-		    __entry->last = last;
-		    __entry->nr = msg->msg_iter.nr_segs;
-		    __entry->bytes = msg->msg_iter.count;
-		    __entry->offset = offset;
 		    __entry->flags = msg->msg_flags;
+		    __entry->offset = msg->msg_iter.xarray_start + msg->msg_iter.iov_offset;
+		    __entry->count = iov_iter_count(&msg->msg_iter);
 			   ),
 
-	    TP_printk(" c=%08x %lx-%lx-%lx b=%x o=%x f=%x",
-		      __entry->call,
-		      __entry->first, __entry->first + __entry->nr - 1, __entry->last,
-		      __entry->bytes, __entry->offset,
+	    TP_printk(" c=%08x o=%llx n=%llx f=%x",
+		      __entry->call, __entry->offset, __entry->count,
 		      __entry->flags)
 	    );
 
-TRACE_EVENT(afs_sent_pages,
-	    TP_PROTO(struct afs_call *call, pgoff_t first, pgoff_t last,
-		     pgoff_t cursor, int ret),
+TRACE_EVENT(afs_sent_data,
+	    TP_PROTO(struct afs_call *call, struct msghdr *msg, int ret),
 
-	    TP_ARGS(call, first, last, cursor, ret),
+	    TP_ARGS(call, msg, ret),
 
 	    TP_STRUCT__entry(
 		    __field(unsigned int,		call		)
-		    __field(pgoff_t,			first		)
-		    __field(pgoff_t,			last		)
-		    __field(pgoff_t,			cursor		)
 		    __field(int,			ret		)
+		    __field(loff_t,			offset		)
+		    __field(loff_t,			count		)
 			     ),
 
 	    TP_fast_assign(
 		    __entry->call = call->debug_id;
-		    __entry->first = first;
-		    __entry->last = last;
-		    __entry->cursor = cursor;
 		    __entry->ret = ret;
+		    __entry->offset = msg->msg_iter.xarray_start + msg->msg_iter.iov_offset;
+		    __entry->count = iov_iter_count(&msg->msg_iter);
 			   ),
 
-	    TP_printk(" c=%08x %lx-%lx c=%lx r=%d",
-		      __entry->call,
-		      __entry->first, __entry->last,
-		      __entry->cursor, __entry->ret)
+	    TP_printk(" c=%08x o=%llx n=%llx r=%x",
+		      __entry->call, __entry->offset, __entry->count,
+		      __entry->ret)
 	    );
 
 TRACE_EVENT(afs_dir_check_failed,



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 20/32] afs: Wait on PG_fscache before modifying/releasing a page
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (18 preceding siblings ...)
  2021-01-25 21:34 ` [PATCH 19/32] afs: Use ITER_XARRAY for writing David Howells
@ 2021-01-25 21:34 ` David Howells
  2021-01-25 21:35 ` [PATCH 21/32] afs: Extract writeback extension into its own function David Howells
                   ` (11 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:34 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

PG_fscache is going to be used to indicate that a page is being written to
the cache, and that the page should not be modified or released until it's
finished.

Make afs_invalidatepage() and afs_releasepage() wait for it.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/file.c  |    9 +++++++++
 fs/afs/write.c |   10 ++++++++++
 2 files changed, 19 insertions(+)

diff --git a/fs/afs/file.c b/fs/afs/file.c
index f1bab69e99d4..acbc21a8c80e 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -594,6 +594,7 @@ static void afs_invalidatepage(struct page *page, unsigned int offset,
 	if (PagePrivate(page))
 		afs_invalidate_dirty(page, offset, length);
 
+	wait_on_page_fscache(page);
 	_leave("");
 }
 
@@ -611,6 +612,14 @@ static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 
 	/* deny if page is being written to the cache and the caller hasn't
 	 * elected to wait */
+#ifdef CONFIG_AFS_FSCACHE
+	if (PageFsCache(page)) {
+		if (!(gfp_flags & __GFP_DIRECT_RECLAIM) || !(gfp_flags & __GFP_FS))
+			return false;
+		wait_on_page_fscache(page);
+	}
+#endif
+
 	if (PagePrivate(page)) {
 		detach_page_private(page);
 		trace_afs_page_dirty(vnode, tracepoint_string("rel"), page);
diff --git a/fs/afs/write.c b/fs/afs/write.c
index dd4dc1c868b5..e1791de90478 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -117,6 +117,10 @@ int afs_write_begin(struct file *file, struct address_space *mapping,
 		SetPageUptodate(page);
 	}
 
+#ifdef CONFIG_AFS_FSCACHE
+	wait_on_page_fscache(page);
+#endif
+
 try_again:
 	/* See if this page is already partially written in a way that we can
 	 * merge the new write with.
@@ -857,6 +861,11 @@ vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
 	/* Wait for the page to be written to the cache before we allow it to
 	 * be modified.  We then assume the entire page will need writing back.
 	 */
+#ifdef CONFIG_AFS_FSCACHE
+	if (PageFsCache(vmf->page) &&
+	    wait_on_page_bit_killable(vmf->page, PG_fscache) < 0)
+		return VM_FAULT_RETRY;
+#endif
 
 	if (PageWriteback(vmf->page) &&
 	    wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
@@ -948,5 +957,6 @@ int afs_launder_page(struct page *page)
 
 	detach_page_private(page);
 	trace_afs_page_dirty(vnode, tracepoint_string("laundered"), page);
+	wait_on_page_fscache(page);
 	return ret;
 }



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 21/32] afs: Extract writeback extension into its own function
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (19 preceding siblings ...)
  2021-01-25 21:34 ` [PATCH 20/32] afs: Wait on PG_fscache before modifying/releasing a page David Howells
@ 2021-01-25 21:35 ` David Howells
  2021-01-25 21:35 ` [PATCH 22/32] afs: Prepare for use of THPs David Howells
                   ` (10 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:35 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Extract writeback extension into its own function to break up the writeback
function a bit.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/write.c |  109 ++++++++++++++++++++++++++++++++++----------------------
 1 file changed, 67 insertions(+), 42 deletions(-)

diff --git a/fs/afs/write.c b/fs/afs/write.c
index e1791de90478..89c804bfe253 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -490,47 +490,25 @@ static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter,
 }
 
 /*
- * Synchronously write back the locked page and any subsequent non-locked dirty
- * pages.
+ * Extend the region to be written back to include subsequent contiguously
+ * dirty pages if possible, but don't sleep while doing so.
+ *
+ * If this page holds new content, then we can include filler zeros in the
+ * writeback.
  */
-static int afs_write_back_from_locked_page(struct address_space *mapping,
-					   struct writeback_control *wbc,
-					   struct page *primary_page,
-					   pgoff_t final_page)
+static void afs_extend_writeback(struct address_space *mapping,
+				 struct afs_vnode *vnode,
+				 long *_count,
+				 pgoff_t start,
+				 pgoff_t final_page,
+				 unsigned *_offset,
+				 unsigned *_to,
+				 bool new_content)
 {
-	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
-	struct iov_iter iter;
 	struct page *pages[8], *page;
-	unsigned long count, priv;
-	unsigned n, offset, to, f, t;
-	pgoff_t start, first, last;
-	loff_t i_size, pos, end;
-	int loop, ret;
-
-	_enter(",%lx", primary_page->index);
-
-	count = 1;
-	if (test_set_page_writeback(primary_page))
-		BUG();
-
-	/* Find all consecutive lockable dirty pages that have contiguous
-	 * written regions, stopping when we find a page that is not
-	 * immediately lockable, is not dirty or is missing, or we reach the
-	 * end of the range.
-	 */
-	start = primary_page->index;
-	priv = page_private(primary_page);
-	offset = afs_page_dirty_from(primary_page, priv);
-	to = afs_page_dirty_to(primary_page, priv);
-	trace_afs_page_dirty(vnode, tracepoint_string("store"), primary_page);
-
-	WARN_ON(offset == to);
-	if (offset == to)
-		trace_afs_page_dirty(vnode, tracepoint_string("WARN"), primary_page);
-
-	if (start >= final_page ||
-	    (to < PAGE_SIZE && !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)))
-		goto no_more;
+	unsigned long count = *_count, priv;
+	unsigned offset = *_offset, to = *_to, n, f, t;
+	int loop;
 
 	start++;
 	do {
@@ -551,8 +529,7 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
 
 		for (loop = 0; loop < n; loop++) {
 			page = pages[loop];
-			if (to != PAGE_SIZE &&
-			    !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags))
+			if (to != PAGE_SIZE && !new_content)
 				break;
 			if (page->index > final_page)
 				break;
@@ -566,8 +543,7 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
 			priv = page_private(page);
 			f = afs_page_dirty_from(page, priv);
 			t = afs_page_dirty_to(page, priv);
-			if (f != 0 &&
-			    !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)) {
+			if (f != 0 && !new_content) {
 				unlock_page(page);
 				break;
 			}
@@ -593,6 +569,55 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
 	} while (start <= final_page && count < 65536);
 
 no_more:
+	*_count = count;
+	*_offset = offset;
+	*_to = to;
+}
+
+/*
+ * Synchronously write back the locked page and any subsequent non-locked dirty
+ * pages.
+ */
+static int afs_write_back_from_locked_page(struct address_space *mapping,
+					   struct writeback_control *wbc,
+					   struct page *primary_page,
+					   pgoff_t final_page)
+{
+	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
+	struct iov_iter iter;
+	unsigned long count, priv;
+	unsigned offset, to;
+	pgoff_t start, first, last;
+	loff_t i_size, pos, end;
+	bool new_content = test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
+	int ret;
+
+	_enter(",%lx", primary_page->index);
+
+	count = 1;
+	if (test_set_page_writeback(primary_page))
+		BUG();
+
+	/* Find all consecutive lockable dirty pages that have contiguous
+	 * written regions, stopping when we find a page that is not
+	 * immediately lockable, is not dirty or is missing, or we reach the
+	 * end of the range.
+	 */
+	start = primary_page->index;
+	priv = page_private(primary_page);
+	offset = afs_page_dirty_from(primary_page, priv);
+	to = afs_page_dirty_to(primary_page, priv);
+	trace_afs_page_dirty(vnode, tracepoint_string("store"), primary_page);
+
+	WARN_ON(offset == to);
+	if (offset == to)
+		trace_afs_page_dirty(vnode, tracepoint_string("WARN"), primary_page);
+
+	if (start < final_page &&
+	    (to == PAGE_SIZE || new_content))
+		afs_extend_writeback(mapping, vnode, &count, start, final_page,
+				     &offset, &to, new_content);
+
 	/* We now have a contiguous set of dirty pages, each with writeback
 	 * set; the first page is still locked at this point, but all the rest
 	 * have been unlocked.



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 22/32] afs: Prepare for use of THPs
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (20 preceding siblings ...)
  2021-01-25 21:35 ` [PATCH 21/32] afs: Extract writeback extension into its own function David Howells
@ 2021-01-25 21:35 ` David Howells
  2021-01-25 21:35 ` [PATCH 23/32] afs: Use the fs operation ops to handle FetchData completion David Howells
                   ` (9 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:35 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

As a prelude to supporting transparent huge pages, use thp_size() and
similar rather than PAGE_SIZE/SHIFT.

Further, try and frame everything in terms of file positions and lengths
rather than page indices and numbers of pages.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/dir.c      |    2 
 fs/afs/file.c     |    8 -
 fs/afs/internal.h |    2 
 fs/afs/write.c    |  436 +++++++++++++++++++++++++++++------------------------
 4 files changed, 245 insertions(+), 203 deletions(-)

diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index 6439ea18667f..8f858b6395fa 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -2082,6 +2082,6 @@ static void afs_dir_invalidatepage(struct page *page, unsigned int offset,
 		afs_stat_v(dvnode, n_inval);
 
 	/* we clean up only if the entire page is being invalidated */
-	if (offset == 0 && length == PAGE_SIZE)
+	if (offset == 0 && length == thp_size(page))
 		detach_page_private(page);
 }
diff --git a/fs/afs/file.c b/fs/afs/file.c
index acbc21a8c80e..f6282ac0d222 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -330,8 +330,8 @@ static int afs_page_filler(struct key *key, struct page *page)
 	req->vnode		= vnode;
 	req->key		= key_get(key);
 	req->pos		= (loff_t)page->index << PAGE_SHIFT;
-	req->len		= PAGE_SIZE;
-	req->nr_pages		= 1;
+	req->len		= thp_size(page);
+	req->nr_pages		= thp_nr_pages(page);
 	req->done		= afs_file_read_done;
 	req->cleanup		= afs_file_read_cleanup;
 
@@ -575,8 +575,8 @@ static void afs_invalidate_dirty(struct page *page, unsigned int offset,
 	trace_afs_page_dirty(vnode, tracepoint_string("undirty"), page);
 	clear_page_dirty_for_io(page);
 full_invalidate:
-	detach_page_private(page);
 	trace_afs_page_dirty(vnode, tracepoint_string("inval"), page);
+	detach_page_private(page);
 }
 
 /*
@@ -621,8 +621,8 @@ static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 #endif
 
 	if (PagePrivate(page)) {
-		detach_page_private(page);
 		trace_afs_page_dirty(vnode, tracepoint_string("rel"), page);
+		detach_page_private(page);
 	}
 
 	/* indicate that the page can be released */
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index d4163f9babfd..daf5339ae316 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -815,8 +815,6 @@ struct afs_operation {
 			loff_t	pos;
 			loff_t	size;
 			loff_t	i_size;
-			pgoff_t	first;		/* first page in mapping to deal with */
-			pgoff_t	last;		/* last page in mapping to deal with */
 			bool	laundering;	/* Laundering page, PG_writeback not set */
 		} store;
 		struct {
diff --git a/fs/afs/write.c b/fs/afs/write.c
index 89c804bfe253..e672833c99bc 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -94,15 +94,15 @@ int afs_write_begin(struct file *file, struct address_space *mapping,
 	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 	struct page *page;
 	unsigned long priv;
-	unsigned f, from = pos & (PAGE_SIZE - 1);
-	unsigned t, to = from + len;
-	pgoff_t index = pos >> PAGE_SHIFT;
+	unsigned f, from;
+	unsigned t, to;
+	pgoff_t index;
 	int ret;
 
-	_enter("{%llx:%llu},{%lx},%u,%u",
-	       vnode->fid.vid, vnode->fid.vnode, index, from, to);
+	_enter("{%llx:%llu},%llx,%x",
+	       vnode->fid.vid, vnode->fid.vnode, pos, len);
 
-	page = grab_cache_page_write_begin(mapping, index, flags);
+	page = grab_cache_page_write_begin(mapping, pos / PAGE_SIZE, flags);
 	if (!page)
 		return -ENOMEM;
 
@@ -121,19 +121,20 @@ int afs_write_begin(struct file *file, struct address_space *mapping,
 	wait_on_page_fscache(page);
 #endif
 
+	index = page->index;
+	from = pos - index * PAGE_SIZE;
+	to = from + len;
+
 try_again:
 	/* See if this page is already partially written in a way that we can
 	 * merge the new write with.
 	 */
-	t = f = 0;
 	if (PagePrivate(page)) {
 		priv = page_private(page);
 		f = afs_page_dirty_from(page, priv);
 		t = afs_page_dirty_to(page, priv);
 		ASSERTCMP(f, <=, t);
-	}
 
-	if (f != t) {
 		if (PageWriteback(page)) {
 			trace_afs_page_dirty(vnode, tracepoint_string("alrdy"), page);
 			goto flush_conflicting_write;
@@ -180,7 +181,7 @@ int afs_write_end(struct file *file, struct address_space *mapping,
 {
 	struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 	unsigned long priv;
-	unsigned int f, from = pos & (PAGE_SIZE - 1);
+	unsigned int f, from = pos & (thp_size(page) - 1);
 	unsigned int t, to = from + copied;
 	loff_t i_size, maybe_i_size;
 	int ret = 0;
@@ -233,9 +234,8 @@ int afs_write_end(struct file *file, struct address_space *mapping,
 		trace_afs_page_dirty(vnode, tracepoint_string("dirty"), page);
 	}
 
-	set_page_dirty(page);
-	if (PageDirty(page))
-		_debug("dirtied");
+	if (set_page_dirty(page))
+		_debug("dirtied %lx", page->index);
 	ret = copied;
 
 out:
@@ -248,40 +248,43 @@ int afs_write_end(struct file *file, struct address_space *mapping,
  * kill all the pages in the given range
  */
 static void afs_kill_pages(struct address_space *mapping,
-			   pgoff_t first, pgoff_t last)
+			   loff_t start, loff_t len)
 {
 	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 	struct pagevec pv;
-	unsigned count, loop;
+	unsigned int loop, psize;
 
-	_enter("{%llx:%llu},%lx-%lx",
-	       vnode->fid.vid, vnode->fid.vnode, first, last);
+	_enter("{%llx:%llu},%llx @%llx",
+	       vnode->fid.vid, vnode->fid.vnode, len, start);
 
 	pagevec_init(&pv);
 
 	do {
-		_debug("kill %lx-%lx", first, last);
+		_debug("kill %llx @%llx", len, start);
 
-		count = last - first + 1;
-		if (count > PAGEVEC_SIZE)
-			count = PAGEVEC_SIZE;
-		pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
-		ASSERTCMP(pv.nr, ==, count);
+		pv.nr = find_get_pages_contig(mapping, start / PAGE_SIZE,
+					      PAGEVEC_SIZE, pv.pages);
+		if (pv.nr == 0)
+			break;
 
-		for (loop = 0; loop < count; loop++) {
+		for (loop = 0; loop < pv.nr; loop++) {
 			struct page *page = pv.pages[loop];
+
+			if (page->index * PAGE_SIZE >= start + len)
+				break;
+
+			psize = thp_size(page);
+			start += psize;
+			len -= psize;
 			ClearPageUptodate(page);
-			SetPageError(page);
 			end_page_writeback(page);
-			if (page->index >= first)
-				first = page->index + 1;
 			lock_page(page);
 			generic_error_remove_page(mapping, page);
 			unlock_page(page);
 		}
 
 		__pagevec_release(&pv);
-	} while (first <= last);
+	} while (len > 0);
 
 	_leave("");
 }
@@ -291,37 +294,40 @@ static void afs_kill_pages(struct address_space *mapping,
  */
 static void afs_redirty_pages(struct writeback_control *wbc,
 			      struct address_space *mapping,
-			      pgoff_t first, pgoff_t last)
+			      loff_t start, loff_t len)
 {
 	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 	struct pagevec pv;
-	unsigned count, loop;
+	unsigned int loop, psize;
 
-	_enter("{%llx:%llu},%lx-%lx",
-	       vnode->fid.vid, vnode->fid.vnode, first, last);
+	_enter("{%llx:%llu},%llx @%llx",
+	       vnode->fid.vid, vnode->fid.vnode, len, start);
 
 	pagevec_init(&pv);
 
 	do {
-		_debug("redirty %lx-%lx", first, last);
+		_debug("redirty %llx @%llx", len, start);
 
-		count = last - first + 1;
-		if (count > PAGEVEC_SIZE)
-			count = PAGEVEC_SIZE;
-		pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
-		ASSERTCMP(pv.nr, ==, count);
+		pv.nr = find_get_pages_contig(mapping, start / PAGE_SIZE,
+					      PAGEVEC_SIZE, pv.pages);
+		if (pv.nr == 0)
+			break;
 
-		for (loop = 0; loop < count; loop++) {
+		for (loop = 0; loop < pv.nr; loop++) {
 			struct page *page = pv.pages[loop];
 
+			if (page->index * PAGE_SIZE >= start + len)
+				break;
+
+			psize = thp_size(page);
+			start += psize;
+			len -= psize;
 			redirty_page_for_writepage(wbc, page);
 			end_page_writeback(page);
-			if (page->index >= first)
-				first = page->index + 1;
 		}
 
 		__pagevec_release(&pv);
-	} while (first <= last);
+	} while (len > 0);
 
 	_leave("");
 }
@@ -329,23 +335,28 @@ static void afs_redirty_pages(struct writeback_control *wbc,
 /*
  * completion of write to server
  */
-static void afs_pages_written_back(struct afs_vnode *vnode, pgoff_t start, pgoff_t last)
+static void afs_pages_written_back(struct afs_vnode *vnode, loff_t start, unsigned int len)
 {
 	struct address_space *mapping = vnode->vfs_inode.i_mapping;
 	struct page *page;
+	pgoff_t end;
 
-	XA_STATE(xas, &mapping->i_pages, start);
+	XA_STATE(xas, &mapping->i_pages, start / PAGE_SIZE);
 
-	_enter("{%llx:%llu},{%lx-%lx}",
-	       vnode->fid.vid, vnode->fid.vnode, start, last);
+	_enter("{%llx:%llu},{%x @%llx}",
+	       vnode->fid.vid, vnode->fid.vnode, len, start);
 
 	rcu_read_lock();
 
-	xas_for_each(&xas, page, last) {
-		ASSERT(PageWriteback(page));
+	end = (start + len - 1) / PAGE_SIZE;
+	xas_for_each(&xas, page, end) {
+		if (!PageWriteback(page)) {
+			kdebug("bad %x @%llx page %lx %lx", len, start, page->index, end);
+			ASSERT(PageWriteback(page));
+		}
 
-		detach_page_private(page);
 		trace_afs_page_dirty(vnode, tracepoint_string("clear"), page);
+		detach_page_private(page);
 		page_endio(page, true, 0);
 	}
 
@@ -404,7 +415,7 @@ static void afs_store_data_success(struct afs_operation *op)
 	afs_vnode_commit_status(op, &op->file[0]);
 	if (op->error == 0) {
 		if (!op->store.laundering)
-			afs_pages_written_back(vnode, op->store.first, op->store.last);
+			afs_pages_written_back(vnode, op->store.pos, op->store.size);
 		afs_stat_v(vnode, n_stores);
 		atomic_long_add(op->store.size, &afs_v2net(vnode)->n_store_bytes);
 	}
@@ -419,8 +430,7 @@ static const struct afs_operation_ops afs_store_data_operation = {
 /*
  * write to a file
  */
-static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter,
-			  loff_t pos, pgoff_t first, pgoff_t last,
+static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter, loff_t pos,
 			  bool laundering)
 {
 	struct afs_operation *op;
@@ -453,8 +463,6 @@ static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter,
 	op->file[0].dv_delta = 1;
 	op->store.write_iter = iter;
 	op->store.pos = pos;
-	op->store.first = first;
-	op->store.last = last;
 	op->store.size = size;
 	op->store.i_size = max(pos + size, i_size);
 	op->store.laundering = laundering;
@@ -499,40 +507,49 @@ static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter,
 static void afs_extend_writeback(struct address_space *mapping,
 				 struct afs_vnode *vnode,
 				 long *_count,
-				 pgoff_t start,
-				 pgoff_t final_page,
-				 unsigned *_offset,
-				 unsigned *_to,
-				 bool new_content)
+				 loff_t start,
+				 loff_t max_len,
+				 bool new_content,
+				 unsigned int *_len)
 {
-	struct page *pages[8], *page;
-	unsigned long count = *_count, priv;
-	unsigned offset = *_offset, to = *_to, n, f, t;
-	int loop;
+	struct pagevec pvec;
+	struct page *page;
+	unsigned long priv;
+	unsigned int psize, filler = 0;
+	unsigned int f, t;
+	loff_t len = *_len;
+	pgoff_t index = (start + len) / PAGE_SIZE;
+	bool stop = true;
+	unsigned int i;
+
+	XA_STATE(xas, &mapping->i_pages, index);
+	pagevec_init(&pvec);
 
-	start++;
 	do {
-		_debug("more %lx [%lx]", start, count);
-		n = final_page - start + 1;
-		if (n > ARRAY_SIZE(pages))
-			n = ARRAY_SIZE(pages);
-		n = find_get_pages_contig(mapping, start, ARRAY_SIZE(pages), pages);
-		_debug("fgpc %u", n);
-		if (n == 0)
-			goto no_more;
-		if (pages[0]->index != start) {
-			do {
-				put_page(pages[--n]);
-			} while (n > 0);
-			goto no_more;
-		}
+		/* Firstly, we gather up a batch of contiguous dirty pages
+		 * under the RCU read lock - but we can't clear the dirty flags
+		 * there if any of those pages are mapped.
+		 */
+		rcu_read_lock();
 
-		for (loop = 0; loop < n; loop++) {
-			page = pages[loop];
-			if (to != PAGE_SIZE && !new_content)
+		xas_for_each(&xas, page, ULONG_MAX) {
+			stop = true;
+			if (xas_retry(&xas, page))
+				continue;
+			if (xa_is_value(page))
+				break;
+			if (page->index != index)
 				break;
-			if (page->index > final_page)
+
+			if (!page_cache_get_speculative(page)) {
+				xas_reset(&xas);
+				continue;
+			}
+
+			/* Has the page moved or been split? */
+			if (unlikely(page != xas_reload(&xas)))
 				break;
+
 			if (!trylock_page(page))
 				break;
 			if (!PageDirty(page) || PageWriteback(page)) {
@@ -540,6 +557,7 @@ static void afs_extend_writeback(struct address_space *mapping,
 				break;
 			}
 
+			psize = thp_size(page);
 			priv = page_private(page);
 			f = afs_page_dirty_from(page, priv);
 			t = afs_page_dirty_to(page, priv);
@@ -547,110 +565,126 @@ static void afs_extend_writeback(struct address_space *mapping,
 				unlock_page(page);
 				break;
 			}
-			to = t;
 
+			len += filler + t;
+			filler = psize - t;
+			if (len >= max_len || *_count <= 0)
+				stop = true;
+			else if (t == psize || new_content)
+				stop = false;
+
+			index += thp_nr_pages(page);
+			if (!pagevec_add(&pvec, page))
+				break;
+			if (stop)
+				break;
+		}
+
+		if (!stop)
+			xas_pause(&xas);
+		rcu_read_unlock();
+
+		/* Now, if we obtained any pages, we can shift them to being
+		 * writable and mark them for caching.
+		 */
+		if (!pagevec_count(&pvec))
+			break;
+
+		for (i = 0; i < pagevec_count(&pvec); i++) {
+			page = pvec.pages[i];
 			trace_afs_page_dirty(vnode, tracepoint_string("store+"), page);
 
 			if (!clear_page_dirty_for_io(page))
 				BUG();
 			if (test_set_page_writeback(page))
 				BUG();
+
+			*_count -= thp_nr_pages(page);
 			unlock_page(page);
-			put_page(page);
-		}
-		count += loop;
-		if (loop < n) {
-			for (; loop < n; loop++)
-				put_page(pages[loop]);
-			goto no_more;
 		}
 
-		start += loop;
-	} while (start <= final_page && count < 65536);
+		pagevec_release(&pvec);
+		cond_resched();
+	} while (!stop);
 
-no_more:
-	*_count = count;
-	*_offset = offset;
-	*_to = to;
+	*_len = len;
 }
 
 /*
  * Synchronously write back the locked page and any subsequent non-locked dirty
  * pages.
  */
-static int afs_write_back_from_locked_page(struct address_space *mapping,
-					   struct writeback_control *wbc,
-					   struct page *primary_page,
-					   pgoff_t final_page)
+static ssize_t afs_write_back_from_locked_page(struct address_space *mapping,
+					       struct writeback_control *wbc,
+					       struct page *page,
+					       loff_t start, loff_t end)
 {
 	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 	struct iov_iter iter;
-	unsigned long count, priv;
-	unsigned offset, to;
-	pgoff_t start, first, last;
-	loff_t i_size, pos, end;
+	unsigned long priv;
+	unsigned int offset, to, len, max_len;
+	loff_t i_size = i_size_read(&vnode->vfs_inode);
 	bool new_content = test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
+	long count = wbc->nr_to_write;
 	int ret;
 
-	_enter(",%lx", primary_page->index);
+	_enter(",%lx,%llx-%llx", page->index, start, end);
 
-	count = 1;
-	if (test_set_page_writeback(primary_page))
+	if (test_set_page_writeback(page))
 		BUG();
 
+	count -= thp_nr_pages(page);
+
 	/* Find all consecutive lockable dirty pages that have contiguous
 	 * written regions, stopping when we find a page that is not
 	 * immediately lockable, is not dirty or is missing, or we reach the
 	 * end of the range.
 	 */
-	start = primary_page->index;
-	priv = page_private(primary_page);
-	offset = afs_page_dirty_from(primary_page, priv);
-	to = afs_page_dirty_to(primary_page, priv);
-	trace_afs_page_dirty(vnode, tracepoint_string("store"), primary_page);
-
-	WARN_ON(offset == to);
-	if (offset == to)
-		trace_afs_page_dirty(vnode, tracepoint_string("WARN"), primary_page);
-
-	if (start < final_page &&
-	    (to == PAGE_SIZE || new_content))
-		afs_extend_writeback(mapping, vnode, &count, start, final_page,
-				     &offset, &to, new_content);
+	priv = page_private(page);
+	offset = afs_page_dirty_from(page, priv);
+	to = afs_page_dirty_to(page, priv);
+	trace_afs_page_dirty(vnode, tracepoint_string("store"), page);
+
+	len = to - offset;
+	start += offset;
+	if (start < i_size) {
+		/* Trim the write to the EOF; the extra data is ignored.  Also
+		 * put an upper limit on the size of a single storedata op.
+		 */
+		max_len = 65536 * 4096;
+		max_len = min_t(unsigned long long, max_len, end - start + 1);
+		max_len = min_t(unsigned long long, max_len, i_size - start);
+
+		if (len < max_len &&
+		    (to == thp_size(page) || new_content))
+			afs_extend_writeback(mapping, vnode, &count,
+					     start, max_len, new_content, &len);
+		len = min_t(loff_t, len, max_len);
+	}
 
 	/* We now have a contiguous set of dirty pages, each with writeback
 	 * set; the first page is still locked at this point, but all the rest
 	 * have been unlocked.
 	 */
-	unlock_page(primary_page);
-
-	first = primary_page->index;
-	last = first + count - 1;
-	_debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
-
-	pos = first;
-	pos <<= PAGE_SHIFT;
-	pos += offset;
-	end = last;
-	end <<= PAGE_SHIFT;
-	end += to;
+	unlock_page(page);
 
-	/* Trim the actual write down to the EOF */
-	i_size = i_size_read(&vnode->vfs_inode);
-	if (end > i_size)
-		end = i_size;
+	if (start < i_size) {
+		_debug("write back %x @%llx [%llx]", len, start, i_size);
 
-	if (pos < i_size) {
-		iov_iter_xarray(&iter, WRITE, &mapping->i_pages, pos, end - pos);
-		ret = afs_store_data(vnode, &iter, pos, first, last, false);
+		iov_iter_xarray(&iter, WRITE, &mapping->i_pages, start, len);
+		ret = afs_store_data(vnode, &iter, start, false);
 	} else {
+		_debug("write discard %x @%llx [%llx]", len, start, i_size);
+
 		/* The dirty region was entirely beyond the EOF. */
+		afs_pages_written_back(vnode, start, len);
 		ret = 0;
 	}
 
 	switch (ret) {
 	case 0:
-		ret = count;
+		wbc->nr_to_write = count;
+		ret = len;
 		break;
 
 	default:
@@ -662,13 +696,13 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
 	case -EKEYEXPIRED:
 	case -EKEYREJECTED:
 	case -EKEYREVOKED:
-		afs_redirty_pages(wbc, mapping, first, last);
+		afs_redirty_pages(wbc, mapping, start, len);
 		mapping_set_error(mapping, ret);
 		break;
 
 	case -EDQUOT:
 	case -ENOSPC:
-		afs_redirty_pages(wbc, mapping, first, last);
+		afs_redirty_pages(wbc, mapping, start, len);
 		mapping_set_error(mapping, -ENOSPC);
 		break;
 
@@ -680,7 +714,7 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
 	case -ENOMEDIUM:
 	case -ENXIO:
 		trace_afs_file_error(vnode, ret, afs_file_error_writeback_fail);
-		afs_kill_pages(mapping, first, last);
+		afs_kill_pages(mapping, start, len);
 		mapping_set_error(mapping, ret);
 		break;
 	}
@@ -695,19 +729,19 @@ static int afs_write_back_from_locked_page(struct address_space *mapping,
  */
 int afs_writepage(struct page *page, struct writeback_control *wbc)
 {
-	int ret;
+	ssize_t ret;
+	loff_t start;
 
 	_enter("{%lx},", page->index);
 
+	start = page->index * PAGE_SIZE;
 	ret = afs_write_back_from_locked_page(page->mapping, wbc, page,
-					      wbc->range_end >> PAGE_SHIFT);
+					      start, LLONG_MAX - start);
 	if (ret < 0) {
-		_leave(" = %d", ret);
-		return 0;
+		_leave(" = %zd", ret);
+		return ret;
 	}
 
-	wbc->nr_to_write -= ret;
-
 	_leave(" = 0");
 	return 0;
 }
@@ -717,35 +751,46 @@ int afs_writepage(struct page *page, struct writeback_control *wbc)
  */
 static int afs_writepages_region(struct address_space *mapping,
 				 struct writeback_control *wbc,
-				 pgoff_t index, pgoff_t end, pgoff_t *_next)
+				 loff_t start, loff_t end, loff_t *_next)
 {
 	struct page *page;
-	int ret, n;
+	ssize_t ret;
+	int n;
 
-	_enter(",,%lx,%lx,", index, end);
+	_enter("%llx,%llx,", start, end);
 
 	do {
-		n = find_get_pages_range_tag(mapping, &index, end,
-					PAGECACHE_TAG_DIRTY, 1, &page);
+		pgoff_t index = start / PAGE_SIZE;
+
+		n = find_get_pages_range_tag(mapping, &index, end / PAGE_SIZE,
+					     PAGECACHE_TAG_DIRTY, 1, &page);
 		if (!n)
 			break;
 
+		start = (loff_t)page->index * PAGE_SIZE; /* May regress with THPs */
+
 		_debug("wback %lx", page->index);
 
-		/*
-		 * at this point we hold neither the i_pages lock nor the
+		/* At this point we hold neither the i_pages lock nor the
 		 * page lock: the page may be truncated or invalidated
 		 * (changing page->mapping to NULL), or even swizzled
 		 * back from swapper_space to tmpfs file mapping
 		 */
-		ret = lock_page_killable(page);
-		if (ret < 0) {
-			put_page(page);
-			_leave(" = %d", ret);
-			return ret;
+		if (wbc->sync_mode != WB_SYNC_NONE) {
+			ret = lock_page_killable(page);
+			if (ret < 0) {
+				put_page(page);
+				return ret;
+			}
+		} else {
+			if (!trylock_page(page)) {
+				put_page(page);
+				return 0;
+			}
 		}
 
 		if (page->mapping != mapping || !PageDirty(page)) {
+			start += thp_size(page);
 			unlock_page(page);
 			put_page(page);
 			continue;
@@ -761,20 +806,20 @@ static int afs_writepages_region(struct address_space *mapping,
 
 		if (!clear_page_dirty_for_io(page))
 			BUG();
-		ret = afs_write_back_from_locked_page(mapping, wbc, page, end);
+		ret = afs_write_back_from_locked_page(mapping, wbc, page, start, end);
 		put_page(page);
 		if (ret < 0) {
-			_leave(" = %d", ret);
+			_leave(" = %zd", ret);
 			return ret;
 		}
 
-		wbc->nr_to_write -= ret;
+		start += ret * PAGE_SIZE;
 
 		cond_resched();
-	} while (index < end && wbc->nr_to_write > 0);
+	} while (wbc->nr_to_write > 0);
 
-	*_next = index;
-	_leave(" = 0 [%lx]", *_next);
+	*_next = start;
+	_leave(" = 0 [%llx]", *_next);
 	return 0;
 }
 
@@ -785,7 +830,7 @@ int afs_writepages(struct address_space *mapping,
 		   struct writeback_control *wbc)
 {
 	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
-	pgoff_t start, end, next;
+	loff_t start, next;
 	int ret;
 
 	_enter("");
@@ -800,22 +845,19 @@ int afs_writepages(struct address_space *mapping,
 		return 0;
 
 	if (wbc->range_cyclic) {
-		start = mapping->writeback_index;
-		end = -1;
-		ret = afs_writepages_region(mapping, wbc, start, end, &next);
+		start = mapping->writeback_index * PAGE_SIZE;
+		ret = afs_writepages_region(mapping, wbc, start, LLONG_MAX, &next);
 		if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
 			ret = afs_writepages_region(mapping, wbc, 0, start,
 						    &next);
-		mapping->writeback_index = next;
+		mapping->writeback_index = next / PAGE_SIZE;
 	} else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
-		end = (pgoff_t)(LLONG_MAX >> PAGE_SHIFT);
-		ret = afs_writepages_region(mapping, wbc, 0, end, &next);
+		ret = afs_writepages_region(mapping, wbc, 0, LLONG_MAX, &next);
 		if (wbc->nr_to_write > 0)
 			mapping->writeback_index = next;
 	} else {
-		start = wbc->range_start >> PAGE_SHIFT;
-		end = wbc->range_end >> PAGE_SHIFT;
-		ret = afs_writepages_region(mapping, wbc, start, end, &next);
+		ret = afs_writepages_region(mapping, wbc,
+					    wbc->range_start, wbc->range_end, &next);
 	}
 
 	up_read(&vnode->validate_lock);
@@ -873,13 +915,13 @@ int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
  */
 vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
 {
+	struct page *page = thp_head(vmf->page);
 	struct file *file = vmf->vma->vm_file;
 	struct inode *inode = file_inode(file);
 	struct afs_vnode *vnode = AFS_FS_I(inode);
 	unsigned long priv;
 
-	_enter("{{%llx:%llu}},{%lx}",
-	       vnode->fid.vid, vnode->fid.vnode, vmf->page->index);
+	_enter("{{%llx:%llu}},{%lx}", vnode->fid.vid, vnode->fid.vnode, page->index);
 
 	sb_start_pagefault(inode->i_sb);
 
@@ -887,31 +929,33 @@ vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
 	 * be modified.  We then assume the entire page will need writing back.
 	 */
 #ifdef CONFIG_AFS_FSCACHE
-	if (PageFsCache(vmf->page) &&
-	    wait_on_page_bit_killable(vmf->page, PG_fscache) < 0)
+	if (PageFsCache(page) &&
+	    wait_on_page_bit_killable(page, PG_fscache) < 0)
 		return VM_FAULT_RETRY;
 #endif
 
-	if (PageWriteback(vmf->page) &&
-	    wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
+	if (PageWriteback(page) &&
+	    wait_on_page_bit_killable(page, PG_writeback) < 0)
 		return VM_FAULT_RETRY;
 
-	if (lock_page_killable(vmf->page) < 0)
+	if (lock_page_killable(page) < 0)
 		return VM_FAULT_RETRY;
 
 	/* We mustn't change page->private until writeback is complete as that
 	 * details the portion of the page we need to write back and we might
 	 * need to redirty the page if there's a problem.
 	 */
-	wait_on_page_writeback(vmf->page);
+	wait_on_page_writeback(page);
 
-	priv = afs_page_dirty(vmf->page, 0, PAGE_SIZE);
+	priv = afs_page_dirty(page, 0, thp_size(page));
 	priv = afs_page_dirty_mmapped(priv);
-	if (PagePrivate(vmf->page))
-		set_page_private(vmf->page, priv);
-	else
-		attach_page_private(vmf->page, (void *)priv);
-	trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"), vmf->page);
+	if (PagePrivate(page)) {
+		set_page_private(page, priv);
+		trace_afs_page_dirty(vnode, tracepoint_string("mkwrite+"), page);
+	} else {
+		attach_page_private(page, (void *)priv);
+		trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"), page);
+	}
 	file_update_time(file);
 
 	sb_end_pagefault(inode->i_sb);
@@ -964,7 +1008,7 @@ int afs_launder_page(struct page *page)
 	priv = page_private(page);
 	if (clear_page_dirty_for_io(page)) {
 		f = 0;
-		t = PAGE_SIZE;
+		t = thp_size(page);
 		if (PagePrivate(page)) {
 			f = afs_page_dirty_from(page, priv);
 			t = afs_page_dirty_to(page, priv);
@@ -976,12 +1020,12 @@ int afs_launder_page(struct page *page)
 		iov_iter_bvec(&iter, WRITE, bv, 1, bv[0].bv_len);
 
 		trace_afs_page_dirty(vnode, tracepoint_string("launder"), page);
-		ret = afs_store_data(vnode, &iter, (loff_t)page->index << PAGE_SHIFT,
-				     page->index, page->index, true);
+		ret = afs_store_data(vnode, &iter, (loff_t)page->index * PAGE_SIZE,
+				     true);
 	}
 
-	detach_page_private(page);
 	trace_afs_page_dirty(vnode, tracepoint_string("laundered"), page);
+	detach_page_private(page);
 	wait_on_page_fscache(page);
 	return ret;
 }



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 23/32] afs: Use the fs operation ops to handle FetchData completion
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (21 preceding siblings ...)
  2021-01-25 21:35 ` [PATCH 22/32] afs: Prepare for use of THPs David Howells
@ 2021-01-25 21:35 ` David Howells
  2021-01-25 21:35 ` [PATCH 24/32] afs: Use new fscache read helper API David Howells
                   ` (8 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:35 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Use the 'success' and 'aborted' afs_operations_ops methods and add a
'failed' method to handle the completion of an AFS.FetchData,
AFS.FetchData64 or YFS.FetchData64 RPC operation rather than directly
calling the done func pointed to by the afs_read struct from the call
delivery handler.

This means the done function will be called back on error also, not just on
successful completion.

This allows motion towards asynchronous data reception on data fetch calls
and allows any error to be handed off to the fscache read helper in the
same place as a successful completion.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/file.c         |   15 +++++++++++++++
 fs/afs/fs_operation.c |    4 +++-
 fs/afs/fsclient.c     |    3 ---
 fs/afs/internal.h     |    1 +
 fs/afs/yfsclient.c    |    3 ---
 5 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/fs/afs/file.c b/fs/afs/file.c
index f6282ac0d222..231e9fd7882b 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -255,6 +255,19 @@ void afs_put_read(struct afs_read *req)
 	}
 }
 
+static void afs_fetch_data_notify(struct afs_operation *op)
+{
+	struct afs_read *req = op->fetch.req;
+	int error = op->error;
+
+	if (error == -ECONNABORTED)
+		error = afs_abort_to_error(op->ac.abort_code);
+	req->error = error;
+
+	if (req->done)
+		req->done(req);
+}
+
 static void afs_fetch_data_success(struct afs_operation *op)
 {
 	struct afs_vnode *vnode = op->file[0].vnode;
@@ -263,6 +276,7 @@ static void afs_fetch_data_success(struct afs_operation *op)
 	afs_vnode_commit_status(op, &op->file[0]);
 	afs_stat_v(vnode, n_fetches);
 	atomic_long_add(op->fetch.req->actual_len, &op->net->n_fetch_bytes);
+	afs_fetch_data_notify(op);
 }
 
 static void afs_fetch_data_put(struct afs_operation *op)
@@ -276,6 +290,7 @@ static const struct afs_operation_ops afs_fetch_data_operation = {
 	.issue_yfs_rpc	= yfs_fs_fetch_data,
 	.success	= afs_fetch_data_success,
 	.aborted	= afs_check_for_remote_deletion,
+	.failed		= afs_fetch_data_notify,
 	.put		= afs_fetch_data_put,
 };
 
diff --git a/fs/afs/fs_operation.c b/fs/afs/fs_operation.c
index 97cab12b0a6c..938e28a00101 100644
--- a/fs/afs/fs_operation.c
+++ b/fs/afs/fs_operation.c
@@ -195,8 +195,10 @@ void afs_wait_for_operation(struct afs_operation *op)
 	case -ECONNABORTED:
 		if (op->ops->aborted)
 			op->ops->aborted(op);
-		break;
+		fallthrough;
 	default:
+		if (op->ops->failed)
+			op->ops->failed(op);
 		break;
 	}
 
diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c
index 31e6b3635541..5e34f4dbd385 100644
--- a/fs/afs/fsclient.c
+++ b/fs/afs/fsclient.c
@@ -392,9 +392,6 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call)
 		break;
 	}
 
-	if (req->done)
-		req->done(req);
-
 	_leave(" = 0 [done]");
 	return 0;
 }
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index daf5339ae316..d46389406021 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -742,6 +742,7 @@ struct afs_operation_ops {
 	void (*issue_yfs_rpc)(struct afs_operation *op);
 	void (*success)(struct afs_operation *op);
 	void (*aborted)(struct afs_operation *op);
+	void (*failed)(struct afs_operation *op);
 	void (*edit_dir)(struct afs_operation *op);
 	void (*put)(struct afs_operation *op);
 };
diff --git a/fs/afs/yfsclient.c b/fs/afs/yfsclient.c
index 363d6dd276c0..2b35cba8ad62 100644
--- a/fs/afs/yfsclient.c
+++ b/fs/afs/yfsclient.c
@@ -449,9 +449,6 @@ static int yfs_deliver_fs_fetch_data64(struct afs_call *call)
 		break;
 	}
 
-	if (req->done)
-		req->done(req);
-
 	_leave(" = 0 [done]");
 	return 0;
 }



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 24/32] afs: Use new fscache read helper API
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (22 preceding siblings ...)
  2021-01-25 21:35 ` [PATCH 23/32] afs: Use the fs operation ops to handle FetchData completion David Howells
@ 2021-01-25 21:35 ` David Howells
  2021-01-25 21:35 ` [PATCH 25/32] NFS: Clean up nfs_readpage() and nfs_readpages() David Howells
                   ` (7 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:35 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: dhowells, Jeff Layton, David Wysochanski, Matthew Wilcox,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

Make AFS use the new fscache read helpers to implement the VM read
operations:

 - afs_readpage() now hands off responsibility to fscache_readpage().

 - afs_readpages() is gone and replaced with afs_readahead().

 - afs_readahead() just hands off responsibility to fscache_readahead().

These make use of the cache if a cookie is supplied, otherwise just call
the ->issue_op() method a sufficient number of times to complete the entire
request.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/Kconfig    |    1 
 fs/afs/file.c     |  323 +++++++++++++----------------------------------------
 fs/afs/fsclient.c |    1 
 fs/afs/internal.h |    2 
 4 files changed, 81 insertions(+), 246 deletions(-)

diff --git a/fs/afs/Kconfig b/fs/afs/Kconfig
index 1ad211d72b3b..fc8ba9142f2f 100644
--- a/fs/afs/Kconfig
+++ b/fs/afs/Kconfig
@@ -4,6 +4,7 @@ config AFS_FS
 	depends on INET
 	select AF_RXRPC
 	select DNS_RESOLVER
+	select NETFS_SUPPORT
 	help
 	  If you say Y here, you will get an experimental Andrew File System
 	  driver. It currently only supports unsecured read-only AFS access.
diff --git a/fs/afs/file.c b/fs/afs/file.c
index 231e9fd7882b..8ae9c7089e73 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -14,6 +14,7 @@
 #include <linux/gfp.h>
 #include <linux/task_io_accounting_ops.h>
 #include <linux/mm.h>
+#include <linux/netfs.h>
 #include "internal.h"
 
 static int afs_file_mmap(struct file *file, struct vm_area_struct *vma);
@@ -22,8 +23,7 @@ static void afs_invalidatepage(struct page *page, unsigned int offset,
 			       unsigned int length);
 static int afs_releasepage(struct page *page, gfp_t gfp_flags);
 
-static int afs_readpages(struct file *filp, struct address_space *mapping,
-			 struct list_head *pages, unsigned nr_pages);
+static void afs_readahead(struct readahead_control *ractl);
 
 const struct file_operations afs_file_operations = {
 	.open		= afs_open,
@@ -48,7 +48,7 @@ const struct inode_operations afs_file_inode_operations = {
 
 const struct address_space_operations afs_fs_aops = {
 	.readpage	= afs_readpage,
-	.readpages	= afs_readpages,
+	.readahead	= afs_readahead,
 	.set_page_dirty	= afs_set_page_dirty,
 	.launder_page	= afs_launder_page,
 	.releasepage	= afs_releasepage,
@@ -185,61 +185,17 @@ int afs_release(struct inode *inode, struct file *file)
 }
 
 /*
- * Handle completion of a read operation.
+ * Allocate a new read record.
  */
-static void afs_file_read_done(struct afs_read *req)
+struct afs_read *afs_alloc_read(gfp_t gfp)
 {
-	struct afs_vnode *vnode = req->vnode;
-	struct page *page;
-	pgoff_t index = req->pos >> PAGE_SHIFT;
-	pgoff_t last = index + req->nr_pages - 1;
-
-	XA_STATE(xas, &vnode->vfs_inode.i_mapping->i_pages, index);
-
-	if (iov_iter_count(req->iter) > 0) {
-		/* The read was short - clear the excess buffer. */
-		_debug("afterclear %zx %zx %llx/%llx",
-		       req->iter->iov_offset,
-		       iov_iter_count(req->iter),
-		       req->actual_len, req->len);
-		iov_iter_zero(iov_iter_count(req->iter), req->iter);
-	}
-
-	rcu_read_lock();
-	xas_for_each(&xas, page, last) {
-		page_endio(page, false, 0);
-		put_page(page);
-	}
-	rcu_read_unlock();
-
-	task_io_account_read(req->len);
-	req->cleanup = NULL;
-}
-
-/*
- * Dispose of our locks and refs on the pages if the read failed.
- */
-static void afs_file_read_cleanup(struct afs_read *req)
-{
-	struct page *page;
-	pgoff_t index = req->pos >> PAGE_SHIFT;
-	pgoff_t last = index + req->nr_pages - 1;
-
-	if (req->iter) {
-		XA_STATE(xas, &req->vnode->vfs_inode.i_mapping->i_pages, index);
-
-		_enter("%lu,%u,%zu", index, req->nr_pages, iov_iter_count(req->iter));
+	struct afs_read *req;
 
-		rcu_read_lock();
-		xas_for_each(&xas, page, last) {
-			BUG_ON(xa_is_value(page));
-			BUG_ON(PageCompound(page));
+	req = kzalloc(sizeof(struct afs_read), gfp);
+	if (req)
+		refcount_set(&req->usage, 1);
 
-			page_endio(page, false, req->error);
-			put_page(page);
-		}
-		rcu_read_unlock();
-	}
+	return req;
 }
 
 /*
@@ -258,14 +214,20 @@ void afs_put_read(struct afs_read *req)
 static void afs_fetch_data_notify(struct afs_operation *op)
 {
 	struct afs_read *req = op->fetch.req;
+	struct netfs_read_subrequest *subreq = req->subreq;
 	int error = op->error;
 
 	if (error == -ECONNABORTED)
 		error = afs_abort_to_error(op->ac.abort_code);
 	req->error = error;
 
-	if (req->done)
+	if (subreq) {
+		__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
+		netfs_subreq_terminated(subreq, error ?: req->actual_len);
+		req->subreq = NULL;
+	} else if (req->done) {
 		req->done(req);
+	}
 }
 
 static void afs_fetch_data_success(struct afs_operation *op)
@@ -319,222 +281,91 @@ int afs_fetch_data(struct afs_vnode *vnode, struct afs_read *req)
 	return afs_do_sync_operation(op);
 }
 
-/*
- * read page from file, directory or symlink, given a key to use
- */
-static int afs_page_filler(struct key *key, struct page *page)
+static void afs_req_issue_op(struct netfs_read_subrequest *subreq)
 {
-	struct inode *inode = page->mapping->host;
-	struct afs_vnode *vnode = AFS_FS_I(inode);
-	struct afs_read *req;
+	struct afs_vnode *vnode = AFS_FS_I(subreq->rreq->inode);
+	struct afs_read *fsreq;
 	int ret;
 
-	_enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
+	fsreq = afs_alloc_read(GFP_NOFS);
+	if (!fsreq) {
+		subreq->error = -ENOMEM;
+		return;
+	}
 
-	BUG_ON(!PageLocked(page));
+	fsreq->subreq	= subreq;
+	fsreq->pos	= subreq->start + subreq->transferred;
+	fsreq->len	= subreq->len   - subreq->transferred;
+	fsreq->key	= subreq->rreq->netfs_priv;
+	fsreq->vnode	= vnode;
+	fsreq->iter	= &fsreq->def_iter;
 
-	ret = -ESTALE;
-	if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
-		goto error;
+	iov_iter_xarray(&fsreq->def_iter, READ,
+			&fsreq->vnode->vfs_inode.i_mapping->i_pages,
+			fsreq->pos, fsreq->len);
 
-	req = kzalloc(sizeof(struct afs_read), GFP_KERNEL);
-	if (!req)
-		goto enomem;
-
-	refcount_set(&req->usage, 1);
-	req->vnode		= vnode;
-	req->key		= key_get(key);
-	req->pos		= (loff_t)page->index << PAGE_SHIFT;
-	req->len		= thp_size(page);
-	req->nr_pages		= thp_nr_pages(page);
-	req->done		= afs_file_read_done;
-	req->cleanup		= afs_file_read_cleanup;
-
-	get_page(page);
-	iov_iter_xarray(&req->def_iter, READ, &page->mapping->i_pages,
-			req->pos, req->len);
-	req->iter = &req->def_iter;
-
-	ret = afs_fetch_data(vnode, req);
+	ret = afs_fetch_data(fsreq->vnode, fsreq);
 	if (ret < 0)
-		goto fetch_error;
-
-	afs_put_read(req);
-	_leave(" = 0");
-	return 0;
-
-fetch_error:
-	switch (ret) {
-	case -EINTR:
-	case -ENOMEM:
-	case -ERESTARTSYS:
-	case -EAGAIN:
-		afs_put_read(req);
-		goto error;
-	case -ENOENT:
-		_debug("got NOENT from server - marking file deleted and stale");
-		set_bit(AFS_VNODE_DELETED, &vnode->flags);
-		ret = -ESTALE;
-		/* Fall through */
-	default:
-		page_endio(page, false, ret);
-		afs_put_read(req);
-		_leave(" = %d", ret);
-		return ret;
-	}
-
-enomem:
-	ret = -ENOMEM;
-error:
-	unlock_page(page);
-	_leave(" = %d", ret);
-	return ret;
+		subreq->error = ret;
 }
 
-/*
- * read page from file, directory or symlink, given a file to nominate the key
- * to be used
- */
-static int afs_readpage(struct file *file, struct page *page)
+static int afs_symlink_readpage(struct page *page)
 {
-	struct key *key;
+	struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
+	struct afs_read *fsreq;
 	int ret;
 
-	if (file) {
-		key = afs_file_key(file);
-		ASSERT(key != NULL);
-		ret = afs_page_filler(key, page);
-	} else {
-		struct inode *inode = page->mapping->host;
-		key = afs_request_key(AFS_FS_S(inode->i_sb)->cell);
-		if (IS_ERR(key)) {
-			ret = PTR_ERR(key);
-		} else {
-			ret = afs_page_filler(key, page);
-			key_put(key);
-		}
-	}
-	return ret;
-}
-
-/*
- * Read a contiguous set of pages.
- */
-static int afs_readpages_one(struct file *file, struct address_space *mapping,
-			     struct list_head *pages)
-{
-	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
-	struct afs_read *req;
-	struct list_head *p;
-	struct page *first, *page;
-	pgoff_t index;
-	int ret, n;
-
-	/* Count the number of contiguous pages at the front of the list.  Note
-	 * that the list goes prev-wards rather than next-wards.
-	 */
-	first = lru_to_page(pages);
-	index = first->index + 1;
-	n = 1;
-	for (p = first->lru.prev; p != pages; p = p->prev) {
-		page = list_entry(p, struct page, lru);
-		if (page->index != index)
-			break;
-		index++;
-		n++;
-	}
-
-	req = kzalloc(sizeof(struct afs_read), GFP_NOFS);
-	if (!req)
+	fsreq = afs_alloc_read(GFP_NOFS);
+	if (!fsreq)
 		return -ENOMEM;
 
-	refcount_set(&req->usage, 1);
-	req->vnode = vnode;
-	req->key = key_get(afs_file_key(file));
-	req->done = afs_file_read_done;
-	req->cleanup = afs_file_read_cleanup;
-	req->pos = first->index;
-	req->pos <<= PAGE_SHIFT;
-
-	/* Add pages to the LRU until it fails.  We keep the pages ref'd and
-	 * locked until the read is complete.
-	 *
-	 * Note that it's possible for the file size to change whilst we're
-	 * doing this, but we rely on the server returning less than we asked
-	 * for if the file shrank.  We also rely on this to deal with a partial
-	 * page at the end of the file.
-	 */
-	do {
-		page = lru_to_page(pages);
-		list_del(&page->lru);
-		index = page->index;
-		if (add_to_page_cache_lru(page, mapping, index,
-					  readahead_gfp_mask(mapping))) {
-			put_page(page);
-			break;
-		}
-
-		req->nr_pages++;
-	} while (req->nr_pages < n);
-
-	if (req->nr_pages == 0) {
-		afs_put_read(req);
-		return 0;
-	}
-
-	req->len = req->nr_pages * PAGE_SIZE;
-	iov_iter_xarray(&req->def_iter, READ, &file->f_mapping->i_pages,
-			req->pos, req->len);
-	req->iter = &req->def_iter;
+	fsreq->pos	= page->index * PAGE_SIZE;
+	fsreq->len	= PAGE_SIZE;
+	fsreq->vnode	= vnode;
+	fsreq->iter	= &fsreq->def_iter;
+	iov_iter_xarray(&fsreq->def_iter, READ, &page->mapping->i_pages,
+			fsreq->pos, fsreq->len);
 
-	ret = afs_fetch_data(vnode, req);
-	if (ret < 0)
-		goto error;
+	ret = afs_fetch_data(fsreq->vnode, fsreq);
+	page_endio(page, false, ret);
+	return ret;
+}
 
-	afs_put_read(req);
-	return 0;
+static void afs_init_rreq(struct netfs_read_request *rreq, struct file *file)
+{
+	rreq->netfs_priv = key_get(afs_file_key(file));
+}
 
-error:
-	if (ret == -ENOENT) {
-		_debug("got NOENT from server - marking file deleted and stale");
-		set_bit(AFS_VNODE_DELETED, &vnode->flags);
-		ret = -ESTALE;
-	}
+static int afs_begin_cache_operation(struct netfs_read_request *rreq)
+{
+	struct afs_vnode *vnode = AFS_FS_I(rreq->inode);
 
-	afs_put_read(req);
-	return ret;
+	return fscache_begin_read_operation(rreq, afs_vnode_cache(vnode));
 }
 
-/*
- * read a set of pages
- */
-static int afs_readpages(struct file *file, struct address_space *mapping,
-			 struct list_head *pages, unsigned nr_pages)
+static void afs_priv_cleanup(struct address_space *mapping, void *netfs_priv)
 {
-	struct key *key = afs_file_key(file);
-	struct afs_vnode *vnode;
-	int ret = 0;
-
-	_enter("{%d},{%lu},,%d",
-	       key_serial(key), mapping->host->i_ino, nr_pages);
+	key_put(netfs_priv);
+}
 
-	ASSERT(key != NULL);
+static const struct netfs_read_request_ops afs_req_ops = {
+	.init_rreq		= afs_init_rreq,
+	.begin_cache_operation	= afs_begin_cache_operation,
+	.issue_op		= afs_req_issue_op,
+	.cleanup		= afs_priv_cleanup,
+};
 
-	vnode = AFS_FS_I(mapping->host);
-	if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
-		_leave(" = -ESTALE");
-		return -ESTALE;
-	}
+static int afs_readpage(struct file *file, struct page *page)
+{
+	if (!file)
+		return afs_symlink_readpage(page);
 
-	/* attempt to read as many of the pages as possible */
-	while (!list_empty(pages)) {
-		ret = afs_readpages_one(file, mapping, pages);
-		if (ret < 0)
-			break;
-	}
+	return netfs_readpage(file, page, &afs_req_ops, NULL);
+}
 
-	_leave(" = %d [netting]", ret);
-	return ret;
+static void afs_readahead(struct readahead_control *ractl)
+{
+	netfs_readahead(ractl, &afs_req_ops, NULL);
 }
 
 /*
diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c
index 5e34f4dbd385..2f695a260442 100644
--- a/fs/afs/fsclient.c
+++ b/fs/afs/fsclient.c
@@ -10,6 +10,7 @@
 #include <linux/sched.h>
 #include <linux/circ_buf.h>
 #include <linux/iversion.h>
+#include <linux/netfs.h>
 #include "internal.h"
 #include "afs_fs.h"
 #include "xdr_fs.h"
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index d46389406021..090720a9943d 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -207,6 +207,7 @@ struct afs_read {
 	loff_t			file_size;	/* File size returned by server */
 	struct key		*key;		/* The key to use to reissue the read */
 	struct afs_vnode	*vnode;		/* The file being read into. */
+	struct netfs_read_subrequest *subreq;	/* Fscache helper read request this belongs to */
 	afs_dataversion_t	data_version;	/* Version number returned by server */
 	refcount_t		usage;
 	unsigned int		call_debug_id;
@@ -1049,6 +1050,7 @@ extern void afs_put_wb_key(struct afs_wb_key *);
 extern int afs_open(struct inode *, struct file *);
 extern int afs_release(struct inode *, struct file *);
 extern int afs_fetch_data(struct afs_vnode *, struct afs_read *);
+extern struct afs_read *afs_alloc_read(gfp_t);
 extern void afs_put_read(struct afs_read *);
 
 static inline struct afs_read *afs_get_read(struct afs_read *req)



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 25/32] NFS: Clean up nfs_readpage() and nfs_readpages()
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (23 preceding siblings ...)
  2021-01-25 21:35 ` [PATCH 24/32] afs: Use new fscache read helper API David Howells
@ 2021-01-25 21:35 ` David Howells
  2021-01-26  3:59   ` Matthew Wilcox
  2021-01-25 21:36 ` [PATCH 26/32] NFS: In nfs_readpage() only increment NFSIOS_READPAGES when read succeeds David Howells
                   ` (6 subsequent siblings)
  31 siblings, 1 reply; 41+ messages in thread
From: David Howells @ 2021-01-25 21:35 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: Dave Wysochanski, dhowells, Jeff Layton, David Wysochanski,
	Matthew Wilcox, Alexander Viro, linux-cachefs, linux-afs,
	linux-nfs, linux-cifs, ceph-devel, v9fs-developer, linux-fsdevel,
	linux-kernel

From: Dave Wysochanski <dwysocha@redhat.com>

In prep for the new fscache netfs API, refactor nfs_readpage()
and nfs_readpages() for future patches.  No functional change.

Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
---

 fs/nfs/read.c |   45 +++++++++++++++++++++++----------------------
 1 file changed, 23 insertions(+), 22 deletions(-)

diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index eb854f1f86e2..a05fb3904ddf 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -310,11 +310,11 @@ static void nfs_readpage_result(struct rpc_task *task,
  *  -	The error flag is set for this page. This happens only when a
  *	previous async read operation failed.
  */
-int nfs_readpage(struct file *file, struct page *page)
+int nfs_readpage(struct file *filp, struct page *page)
 {
 	struct nfs_open_context *ctx;
 	struct inode *inode = page_file_mapping(page)->host;
-	int		error;
+	int ret;
 
 	dprintk("NFS: nfs_readpage (%p %ld@%lu)\n",
 		page, PAGE_SIZE, page_index(page));
@@ -328,43 +328,43 @@ int nfs_readpage(struct file *file, struct page *page)
 	 * be any new pending writes generated at this point
 	 * for this page (other pages can be written to).
 	 */
-	error = nfs_wb_page(inode, page);
-	if (error)
+	ret = nfs_wb_page(inode, page);
+	if (ret)
 		goto out_unlock;
 	if (PageUptodate(page))
 		goto out_unlock;
 
-	error = -ESTALE;
+	ret = -ESTALE;
 	if (NFS_STALE(inode))
 		goto out_unlock;
 
-	if (file == NULL) {
-		error = -EBADF;
+	if (filp == NULL) {
+		ret = -EBADF;
 		ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
 		if (ctx == NULL)
 			goto out_unlock;
 	} else
-		ctx = get_nfs_open_context(nfs_file_open_context(file));
+		ctx = get_nfs_open_context(nfs_file_open_context(filp));
 
 	if (!IS_SYNC(inode)) {
-		error = nfs_readpage_from_fscache(ctx, inode, page);
-		if (error == 0)
+		ret = nfs_readpage_from_fscache(ctx, inode, page);
+		if (ret == 0)
 			goto out;
 	}
 
 	xchg(&ctx->error, 0);
-	error = nfs_readpage_async(ctx, inode, page);
-	if (!error) {
-		error = wait_on_page_locked_killable(page);
-		if (!PageUptodate(page) && !error)
-			error = xchg(&ctx->error, 0);
+	ret = nfs_readpage_async(ctx, inode, page);
+	if (!ret) {
+		ret = wait_on_page_locked_killable(page);
+		if (!PageUptodate(page) && !ret)
+			ret = xchg(&ctx->error, 0);
 	}
 out:
 	put_nfs_open_context(ctx);
-	return error;
+	return ret;
 out_unlock:
 	unlock_page(page);
-	return error;
+	return ret;
 }
 
 struct nfs_readdesc {
@@ -409,12 +409,10 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
 {
 	struct nfs_pageio_descriptor pgio;
 	struct nfs_pgio_mirror *pgm;
-	struct nfs_readdesc desc = {
-		.pgio = &pgio,
-	};
+	struct nfs_readdesc desc;
 	struct inode *inode = mapping->host;
 	unsigned long npages;
-	int ret = -ESTALE;
+	int ret;
 
 	dprintk("NFS: nfs_readpages (%s/%Lu %d)\n",
 			inode->i_sb->s_id,
@@ -422,13 +420,15 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
 			nr_pages);
 	nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
 
+	ret = -ESTALE;
 	if (NFS_STALE(inode))
 		goto out;
 
 	if (filp == NULL) {
+		ret = -EBADF;
 		desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
 		if (desc.ctx == NULL)
-			return -EBADF;
+			goto out;
 	} else
 		desc.ctx = get_nfs_open_context(nfs_file_open_context(filp));
 
@@ -440,6 +440,7 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
 	if (ret == 0)
 		goto read_complete; /* all pages were read */
 
+	desc.pgio = &pgio;
 	nfs_pageio_init_read(&pgio, inode, false,
 			     &nfs_async_read_completion_ops);
 



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 26/32] NFS: In nfs_readpage() only increment NFSIOS_READPAGES when read succeeds
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (24 preceding siblings ...)
  2021-01-25 21:35 ` [PATCH 25/32] NFS: Clean up nfs_readpage() and nfs_readpages() David Howells
@ 2021-01-25 21:36 ` David Howells
  2021-01-25 21:36 ` [PATCH 27/32] NFS: Refactor nfs_readpage() and nfs_readpage_async() to use nfs_readdesc David Howells
                   ` (5 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:36 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: Dave Wysochanski, dhowells, Jeff Layton, David Wysochanski,
	Matthew Wilcox, Alexander Viro, linux-cachefs, linux-afs,
	linux-nfs, linux-cifs, ceph-devel, v9fs-developer, linux-fsdevel,
	linux-kernel

From: Dave Wysochanski <dwysocha@redhat.com>

There is a small inconsistency with nfs_readpage() vs nfs_readpages() with
regards to NFSIOS_READPAGES.  In readpage we unconditionally increment
NFSIOS_READPAGES at the top, which means even if the read fails.  In
readpages, we increment NFSIOS_READPAGES at the bottom based on how
many pages were successfully read.  Change readpage to be consistent with
readpages and so NFSIOS_READPAGES only reflects successful, non-fscache
reads.

Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
---

 fs/nfs/read.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index a05fb3904ddf..1153c4e0a155 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -319,7 +319,6 @@ int nfs_readpage(struct file *filp, struct page *page)
 	dprintk("NFS: nfs_readpage (%p %ld@%lu)\n",
 		page, PAGE_SIZE, page_index(page));
 	nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
-	nfs_add_stats(inode, NFSIOS_READPAGES, 1);
 
 	/*
 	 * Try to flush any pending writes to the file..
@@ -359,6 +358,7 @@ int nfs_readpage(struct file *filp, struct page *page)
 		if (!PageUptodate(page) && !ret)
 			ret = xchg(&ctx->error, 0);
 	}
+	nfs_add_stats(inode, NFSIOS_READPAGES, 1);
 out:
 	put_nfs_open_context(ctx);
 	return ret;



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 27/32] NFS: Refactor nfs_readpage() and nfs_readpage_async() to use nfs_readdesc
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (25 preceding siblings ...)
  2021-01-25 21:36 ` [PATCH 26/32] NFS: In nfs_readpage() only increment NFSIOS_READPAGES when read succeeds David Howells
@ 2021-01-25 21:36 ` David Howells
  2021-01-26  4:05   ` Matthew Wilcox
  2021-01-25 21:36 ` [PATCH 28/32] NFS: Call readpage_async_filler() from nfs_readpage_async() David Howells
                   ` (4 subsequent siblings)
  31 siblings, 1 reply; 41+ messages in thread
From: David Howells @ 2021-01-25 21:36 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: Dave Wysochanski, dhowells, Jeff Layton, David Wysochanski,
	Matthew Wilcox, Alexander Viro, linux-cachefs, linux-afs,
	linux-nfs, linux-cifs, ceph-devel, v9fs-developer, linux-fsdevel,
	linux-kernel

From: Dave Wysochanski <dwysocha@redhat.com>

Both nfs_readpage() and nfs_readpages() use similar code.
This patch should be no functional change, and refactors
nfs_readpage_async() to use nfs_readdesc to enable future
merging of nfs_readpage_async() and nfs_readpage_async_filler().

Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
---

 fs/nfs/read.c          |   62 +++++++++++++++++++++++-------------------------
 include/linux/nfs_fs.h |    3 +-
 2 files changed, 31 insertions(+), 34 deletions(-)

diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 1153c4e0a155..5fda30742a32 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -114,18 +114,23 @@ static void nfs_readpage_release(struct nfs_page *req, int error)
 	nfs_release_request(req);
 }
 
-int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
+struct nfs_readdesc {
+	struct nfs_pageio_descriptor pgio;
+	struct nfs_open_context *ctx;
+};
+
+int nfs_readpage_async(void *data, struct inode *inode,
 		       struct page *page)
 {
+	struct nfs_readdesc *desc = (struct nfs_readdesc *)data;
 	struct nfs_page	*new;
 	unsigned int len;
-	struct nfs_pageio_descriptor pgio;
 	struct nfs_pgio_mirror *pgm;
 
 	len = nfs_page_length(page);
 	if (len == 0)
 		return nfs_return_empty_page(page);
-	new = nfs_create_request(ctx, page, 0, len);
+	new = nfs_create_request(desc->ctx, page, 0, len);
 	if (IS_ERR(new)) {
 		unlock_page(page);
 		return PTR_ERR(new);
@@ -133,21 +138,21 @@ int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
 	if (len < PAGE_SIZE)
 		zero_user_segment(page, len, PAGE_SIZE);
 
-	nfs_pageio_init_read(&pgio, inode, false,
+	nfs_pageio_init_read(&desc->pgio, inode, false,
 			     &nfs_async_read_completion_ops);
-	if (!nfs_pageio_add_request(&pgio, new)) {
+	if (!nfs_pageio_add_request(&desc->pgio, new)) {
 		nfs_list_remove_request(new);
-		nfs_readpage_release(new, pgio.pg_error);
+		nfs_readpage_release(new, desc->pgio.pg_error);
 	}
-	nfs_pageio_complete(&pgio);
+	nfs_pageio_complete(&desc->pgio);
 
 	/* It doesn't make sense to do mirrored reads! */
-	WARN_ON_ONCE(pgio.pg_mirror_count != 1);
+	WARN_ON_ONCE(desc->pgio.pg_mirror_count != 1);
 
-	pgm = &pgio.pg_mirrors[0];
+	pgm = &desc->pgio.pg_mirrors[0];
 	NFS_I(inode)->read_io += pgm->pg_bytes_written;
 
-	return pgio.pg_error < 0 ? pgio.pg_error : 0;
+	return desc->pgio.pg_error < 0 ? desc->pgio.pg_error : 0;
 }
 
 static void nfs_page_group_set_uptodate(struct nfs_page *req)
@@ -312,7 +317,7 @@ static void nfs_readpage_result(struct rpc_task *task,
  */
 int nfs_readpage(struct file *filp, struct page *page)
 {
-	struct nfs_open_context *ctx;
+	struct nfs_readdesc desc;
 	struct inode *inode = page_file_mapping(page)->host;
 	int ret;
 
@@ -339,39 +344,34 @@ int nfs_readpage(struct file *filp, struct page *page)
 
 	if (filp == NULL) {
 		ret = -EBADF;
-		ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
-		if (ctx == NULL)
+		desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
+		if (desc.ctx == NULL)
 			goto out_unlock;
 	} else
-		ctx = get_nfs_open_context(nfs_file_open_context(filp));
+		desc.ctx = get_nfs_open_context(nfs_file_open_context(filp));
 
 	if (!IS_SYNC(inode)) {
-		ret = nfs_readpage_from_fscache(ctx, inode, page);
+		ret = nfs_readpage_from_fscache(desc.ctx, inode, page);
 		if (ret == 0)
 			goto out;
 	}
 
-	xchg(&ctx->error, 0);
-	ret = nfs_readpage_async(ctx, inode, page);
+	xchg(&desc.ctx->error, 0);
+	ret = nfs_readpage_async(&desc, inode, page);
 	if (!ret) {
 		ret = wait_on_page_locked_killable(page);
 		if (!PageUptodate(page) && !ret)
-			ret = xchg(&ctx->error, 0);
+			ret = xchg(&desc.ctx->error, 0);
 	}
 	nfs_add_stats(inode, NFSIOS_READPAGES, 1);
 out:
-	put_nfs_open_context(ctx);
+	put_nfs_open_context(desc.ctx);
 	return ret;
 out_unlock:
 	unlock_page(page);
 	return ret;
 }
 
-struct nfs_readdesc {
-	struct nfs_pageio_descriptor *pgio;
-	struct nfs_open_context *ctx;
-};
-
 static int
 readpage_async_filler(void *data, struct page *page)
 {
@@ -390,9 +390,9 @@ readpage_async_filler(void *data, struct page *page)
 
 	if (len < PAGE_SIZE)
 		zero_user_segment(page, len, PAGE_SIZE);
-	if (!nfs_pageio_add_request(desc->pgio, new)) {
+	if (!nfs_pageio_add_request(&desc->pgio, new)) {
 		nfs_list_remove_request(new);
-		error = desc->pgio->pg_error;
+		error = desc->pgio.pg_error;
 		nfs_readpage_release(new, error);
 		goto out;
 	}
@@ -407,7 +407,6 @@ readpage_async_filler(void *data, struct page *page)
 int nfs_readpages(struct file *filp, struct address_space *mapping,
 		struct list_head *pages, unsigned nr_pages)
 {
-	struct nfs_pageio_descriptor pgio;
 	struct nfs_pgio_mirror *pgm;
 	struct nfs_readdesc desc;
 	struct inode *inode = mapping->host;
@@ -440,17 +439,16 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
 	if (ret == 0)
 		goto read_complete; /* all pages were read */
 
-	desc.pgio = &pgio;
-	nfs_pageio_init_read(&pgio, inode, false,
+	nfs_pageio_init_read(&desc.pgio, inode, false,
 			     &nfs_async_read_completion_ops);
 
 	ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
-	nfs_pageio_complete(&pgio);
+	nfs_pageio_complete(&desc.pgio);
 
 	/* It doesn't make sense to do mirrored reads! */
-	WARN_ON_ONCE(pgio.pg_mirror_count != 1);
+	WARN_ON_ONCE(desc.pgio.pg_mirror_count != 1);
 
-	pgm = &pgio.pg_mirrors[0];
+	pgm = &desc.pgio.pg_mirrors[0];
 	NFS_I(inode)->read_io += pgm->pg_bytes_written;
 	npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >>
 		 PAGE_SHIFT;
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 681ed98e4ba8..cb0248a34518 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -570,8 +570,7 @@ nfs_have_writebacks(struct inode *inode)
 extern int  nfs_readpage(struct file *, struct page *);
 extern int  nfs_readpages(struct file *, struct address_space *,
 		struct list_head *, unsigned);
-extern int  nfs_readpage_async(struct nfs_open_context *, struct inode *,
-			       struct page *);
+extern int  nfs_readpage_async(void *, struct inode *, struct page *);
 
 /*
  * inline functions



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 28/32] NFS: Call readpage_async_filler() from nfs_readpage_async()
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (26 preceding siblings ...)
  2021-01-25 21:36 ` [PATCH 27/32] NFS: Refactor nfs_readpage() and nfs_readpage_async() to use nfs_readdesc David Howells
@ 2021-01-25 21:36 ` David Howells
  2021-01-25 21:36 ` [PATCH 29/32] NFS: Add nfs_pageio_complete_read() and remove nfs_readpage_async() David Howells
                   ` (3 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:36 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: Dave Wysochanski, dhowells, Jeff Layton, David Wysochanski,
	Matthew Wilcox, Alexander Viro, linux-cachefs, linux-afs,
	linux-nfs, linux-cifs, ceph-devel, v9fs-developer, linux-fsdevel,
	linux-kernel

From: Dave Wysochanski <dwysocha@redhat.com>

Refactor slightly so nfs_readpage_async() calls into
readpage_async_filler().

Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
---

 fs/nfs/read.c |   28 +++++++++++-----------------
 1 file changed, 11 insertions(+), 17 deletions(-)

diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 5fda30742a32..1401f1c734c0 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -119,31 +119,22 @@ struct nfs_readdesc {
 	struct nfs_open_context *ctx;
 };
 
+static int readpage_async_filler(void *data, struct page *page);
+
 int nfs_readpage_async(void *data, struct inode *inode,
 		       struct page *page)
 {
 	struct nfs_readdesc *desc = (struct nfs_readdesc *)data;
-	struct nfs_page	*new;
-	unsigned int len;
 	struct nfs_pgio_mirror *pgm;
-
-	len = nfs_page_length(page);
-	if (len == 0)
-		return nfs_return_empty_page(page);
-	new = nfs_create_request(desc->ctx, page, 0, len);
-	if (IS_ERR(new)) {
-		unlock_page(page);
-		return PTR_ERR(new);
-	}
-	if (len < PAGE_SIZE)
-		zero_user_segment(page, len, PAGE_SIZE);
+	int error;
 
 	nfs_pageio_init_read(&desc->pgio, inode, false,
 			     &nfs_async_read_completion_ops);
-	if (!nfs_pageio_add_request(&desc->pgio, new)) {
-		nfs_list_remove_request(new);
-		nfs_readpage_release(new, desc->pgio.pg_error);
-	}
+
+	error = readpage_async_filler(desc, page);
+	if (error)
+		goto out;
+
 	nfs_pageio_complete(&desc->pgio);
 
 	/* It doesn't make sense to do mirrored reads! */
@@ -153,6 +144,9 @@ int nfs_readpage_async(void *data, struct inode *inode,
 	NFS_I(inode)->read_io += pgm->pg_bytes_written;
 
 	return desc->pgio.pg_error < 0 ? desc->pgio.pg_error : 0;
+
+out:
+	return error;
 }
 
 static void nfs_page_group_set_uptodate(struct nfs_page *req)



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 29/32] NFS: Add nfs_pageio_complete_read() and remove nfs_readpage_async()
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (27 preceding siblings ...)
  2021-01-25 21:36 ` [PATCH 28/32] NFS: Call readpage_async_filler() from nfs_readpage_async() David Howells
@ 2021-01-25 21:36 ` David Howells
  2021-01-25 21:37 ` [PATCH 30/32] NFS: Allow internal use of read structs and functions David Howells
                   ` (2 subsequent siblings)
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:36 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: Dave Wysochanski, dhowells, Jeff Layton, David Wysochanski,
	Matthew Wilcox, Alexander Viro, linux-cachefs, linux-afs,
	linux-nfs, linux-cifs, ceph-devel, v9fs-developer, linux-fsdevel,
	linux-kernel

From: Dave Wysochanski <dwysocha@redhat.com>

Add nfs_pageio_complete_read() and call this from both nfs_readpage()
and nfs_readpages(), since the submission and accounting is the same
for both functions.

Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
---

 fs/nfs/read.c          |  137 +++++++++++++++++++++---------------------------
 include/linux/nfs_fs.h |    1 
 2 files changed, 61 insertions(+), 77 deletions(-)

diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 1401f1c734c0..c2df4040f26c 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -74,6 +74,24 @@ void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
 }
 EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
 
+static void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio,
+				     struct inode *inode)
+{
+	struct nfs_pgio_mirror *pgm;
+	unsigned long npages;
+
+	nfs_pageio_complete(pgio);
+
+	/* It doesn't make sense to do mirrored reads! */
+	WARN_ON_ONCE(pgio->pg_mirror_count != 1);
+
+	pgm = &pgio->pg_mirrors[0];
+	NFS_I(inode)->read_io += pgm->pg_bytes_written;
+	npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	nfs_add_stats(inode, NFSIOS_READPAGES, npages);
+}
+
+
 void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
 {
 	struct nfs_pgio_mirror *mirror;
@@ -119,36 +137,6 @@ struct nfs_readdesc {
 	struct nfs_open_context *ctx;
 };
 
-static int readpage_async_filler(void *data, struct page *page);
-
-int nfs_readpage_async(void *data, struct inode *inode,
-		       struct page *page)
-{
-	struct nfs_readdesc *desc = (struct nfs_readdesc *)data;
-	struct nfs_pgio_mirror *pgm;
-	int error;
-
-	nfs_pageio_init_read(&desc->pgio, inode, false,
-			     &nfs_async_read_completion_ops);
-
-	error = readpage_async_filler(desc, page);
-	if (error)
-		goto out;
-
-	nfs_pageio_complete(&desc->pgio);
-
-	/* It doesn't make sense to do mirrored reads! */
-	WARN_ON_ONCE(desc->pgio.pg_mirror_count != 1);
-
-	pgm = &desc->pgio.pg_mirrors[0];
-	NFS_I(inode)->read_io += pgm->pg_bytes_written;
-
-	return desc->pgio.pg_error < 0 ? desc->pgio.pg_error : 0;
-
-out:
-	return error;
-}
-
 static void nfs_page_group_set_uptodate(struct nfs_page *req)
 {
 	if (nfs_page_group_sync_on_bit(req, PG_UPTODATE))
@@ -170,8 +158,7 @@ static void nfs_read_completion(struct nfs_pgio_header *hdr)
 
 		if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
 			/* note: regions of the page not covered by a
-			 * request are zeroed in nfs_readpage_async /
-			 * readpage_async_filler */
+			 * request are zeroed in readpage_async_filler */
 			if (bytes > hdr->good_bytes) {
 				/* nothing in this request was good, so zero
 				 * the full extent of the request */
@@ -303,6 +290,38 @@ static void nfs_readpage_result(struct rpc_task *task,
 		nfs_readpage_retry(task, hdr);
 }
 
+static int
+readpage_async_filler(void *data, struct page *page)
+{
+	struct nfs_readdesc *desc = (struct nfs_readdesc *)data;
+	struct nfs_page *new;
+	unsigned int len;
+	int error;
+
+	len = nfs_page_length(page);
+	if (len == 0)
+		return nfs_return_empty_page(page);
+
+	new = nfs_create_request(desc->ctx, page, 0, len);
+	if (IS_ERR(new))
+		goto out_error;
+
+	if (len < PAGE_SIZE)
+		zero_user_segment(page, len, PAGE_SIZE);
+	if (!nfs_pageio_add_request(&desc->pgio, new)) {
+		nfs_list_remove_request(new);
+		error = desc->pgio.pg_error;
+		nfs_readpage_release(new, error);
+		goto out;
+	}
+	return 0;
+out_error:
+	error = PTR_ERR(new);
+	unlock_page(page);
+out:
+	return error;
+}
+
 /*
  * Read a page over NFS.
  * We read the page synchronously in the following case:
@@ -351,13 +370,20 @@ int nfs_readpage(struct file *filp, struct page *page)
 	}
 
 	xchg(&desc.ctx->error, 0);
-	ret = nfs_readpage_async(&desc, inode, page);
+	nfs_pageio_init_read(&desc.pgio, inode, false,
+			     &nfs_async_read_completion_ops);
+
+	ret = readpage_async_filler(&desc, page);
+
+	if (!ret)
+		nfs_pageio_complete_read(&desc.pgio, inode);
+
+	ret = desc.pgio.pg_error < 0 ? desc.pgio.pg_error : 0;
 	if (!ret) {
 		ret = wait_on_page_locked_killable(page);
 		if (!PageUptodate(page) && !ret)
 			ret = xchg(&desc.ctx->error, 0);
 	}
-	nfs_add_stats(inode, NFSIOS_READPAGES, 1);
 out:
 	put_nfs_open_context(desc.ctx);
 	return ret;
@@ -366,45 +392,11 @@ int nfs_readpage(struct file *filp, struct page *page)
 	return ret;
 }
 
-static int
-readpage_async_filler(void *data, struct page *page)
-{
-	struct nfs_readdesc *desc = (struct nfs_readdesc *)data;
-	struct nfs_page *new;
-	unsigned int len;
-	int error;
-
-	len = nfs_page_length(page);
-	if (len == 0)
-		return nfs_return_empty_page(page);
-
-	new = nfs_create_request(desc->ctx, page, 0, len);
-	if (IS_ERR(new))
-		goto out_error;
-
-	if (len < PAGE_SIZE)
-		zero_user_segment(page, len, PAGE_SIZE);
-	if (!nfs_pageio_add_request(&desc->pgio, new)) {
-		nfs_list_remove_request(new);
-		error = desc->pgio.pg_error;
-		nfs_readpage_release(new, error);
-		goto out;
-	}
-	return 0;
-out_error:
-	error = PTR_ERR(new);
-	unlock_page(page);
-out:
-	return error;
-}
-
 int nfs_readpages(struct file *filp, struct address_space *mapping,
 		struct list_head *pages, unsigned nr_pages)
 {
-	struct nfs_pgio_mirror *pgm;
 	struct nfs_readdesc desc;
 	struct inode *inode = mapping->host;
-	unsigned long npages;
 	int ret;
 
 	dprintk("NFS: nfs_readpages (%s/%Lu %d)\n",
@@ -437,16 +429,9 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
 			     &nfs_async_read_completion_ops);
 
 	ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
-	nfs_pageio_complete(&desc.pgio);
 
-	/* It doesn't make sense to do mirrored reads! */
-	WARN_ON_ONCE(desc.pgio.pg_mirror_count != 1);
+	nfs_pageio_complete_read(&desc.pgio, inode);
 
-	pgm = &desc.pgio.pg_mirrors[0];
-	NFS_I(inode)->read_io += pgm->pg_bytes_written;
-	npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >>
-		 PAGE_SHIFT;
-	nfs_add_stats(inode, NFSIOS_READPAGES, npages);
 read_complete:
 	put_nfs_open_context(desc.ctx);
 out:
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index cb0248a34518..3cfcf219e96b 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -570,7 +570,6 @@ nfs_have_writebacks(struct inode *inode)
 extern int  nfs_readpage(struct file *, struct page *);
 extern int  nfs_readpages(struct file *, struct address_space *,
 		struct list_head *, unsigned);
-extern int  nfs_readpage_async(void *, struct inode *, struct page *);
 
 /*
  * inline functions



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 30/32] NFS: Allow internal use of read structs and functions
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (28 preceding siblings ...)
  2021-01-25 21:36 ` [PATCH 29/32] NFS: Add nfs_pageio_complete_read() and remove nfs_readpage_async() David Howells
@ 2021-01-25 21:37 ` David Howells
  2021-01-25 21:37 ` [PATCH 31/32] NFS: Convert to the netfs API and nfs_readpage to use netfs_readpage David Howells
  2021-01-25 21:37 ` [PATCH 32/32] NFS: Convert readpage to readahead and use netfs_readahead for fscache David Howells
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:37 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: Dave Wysochanski, dhowells, Jeff Layton, David Wysochanski,
	Matthew Wilcox, Alexander Viro, linux-cachefs, linux-afs,
	linux-nfs, linux-cifs, ceph-devel, v9fs-developer, linux-fsdevel,
	linux-kernel

From: Dave Wysochanski <dwysocha@redhat.com>

The conversion of the NFS read paths to the new fscache API
will require use of a few read structs and functions,
so move these declarations as required.

Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
---

 fs/nfs/internal.h |    8 ++++++++
 fs/nfs/read.c     |   13 ++++---------
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 62d3189745cd..8514d002c922 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -457,9 +457,17 @@ extern int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh, bool
 
 struct nfs_pgio_completion_ops;
 /* read.c */
+extern const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
 extern void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
 			struct inode *inode, bool force_mds,
 			const struct nfs_pgio_completion_ops *compl_ops);
+struct nfs_readdesc {
+	struct nfs_pageio_descriptor pgio;
+	struct nfs_open_context *ctx;
+};
+extern int readpage_async_filler(void *data, struct page *page);
+extern void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio,
+				     struct inode *inode);
 extern void nfs_read_prepare(struct rpc_task *task, void *calldata);
 extern void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio);
 
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index c2df4040f26c..13266eda8f60 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -30,7 +30,7 @@
 
 #define NFSDBG_FACILITY		NFSDBG_PAGECACHE
 
-static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
+const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
 static const struct nfs_rw_ops nfs_rw_read_ops;
 
 static struct kmem_cache *nfs_rdata_cachep;
@@ -74,7 +74,7 @@ void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
 }
 EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
 
-static void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio,
+void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio,
 				     struct inode *inode)
 {
 	struct nfs_pgio_mirror *pgm;
@@ -132,11 +132,6 @@ static void nfs_readpage_release(struct nfs_page *req, int error)
 	nfs_release_request(req);
 }
 
-struct nfs_readdesc {
-	struct nfs_pageio_descriptor pgio;
-	struct nfs_open_context *ctx;
-};
-
 static void nfs_page_group_set_uptodate(struct nfs_page *req)
 {
 	if (nfs_page_group_sync_on_bit(req, PG_UPTODATE))
@@ -215,7 +210,7 @@ nfs_async_read_error(struct list_head *head, int error)
 	}
 }
 
-static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
+const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
 	.error_cleanup = nfs_async_read_error,
 	.completion = nfs_read_completion,
 };
@@ -290,7 +285,7 @@ static void nfs_readpage_result(struct rpc_task *task,
 		nfs_readpage_retry(task, hdr);
 }
 
-static int
+int
 readpage_async_filler(void *data, struct page *page)
 {
 	struct nfs_readdesc *desc = (struct nfs_readdesc *)data;



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 31/32] NFS: Convert to the netfs API and nfs_readpage to use netfs_readpage
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (29 preceding siblings ...)
  2021-01-25 21:37 ` [PATCH 30/32] NFS: Allow internal use of read structs and functions David Howells
@ 2021-01-25 21:37 ` David Howells
  2021-01-25 21:37 ` [PATCH 32/32] NFS: Convert readpage to readahead and use netfs_readahead for fscache David Howells
  31 siblings, 0 replies; 41+ messages in thread
From: David Howells @ 2021-01-25 21:37 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: Dave Wysochanski, dhowells, Jeff Layton, David Wysochanski,
	Matthew Wilcox, Alexander Viro, linux-cachefs, linux-afs,
	linux-nfs, linux-cifs, ceph-devel, v9fs-developer, linux-fsdevel,
	linux-kernel

From: Dave Wysochanski <dwysocha@redhat.com>

This patch converts the main NFS read paths to the new netfs API,
when fscache is enabled, and converts readpage while minimizing
changes to the existing NFS read code paths.

The netfs API requires a few functions to be provided by the
netfs:
- init_rreq: allows netfs to allocate resources prior to IO
- is_cache_enabled: allows netfs to disable fscache
- begin_cache_operation: signals the start of an fscache IO
- issue_op: called when netfs should issue read to server
- clamp_length: allows netfs to limit size of IO
- cleanup: allows netfs to cleanup after an IO is complete

The new netfs_readpage() API is called when fscache is enabled.
If a read cannot be satisfied from fscache, the netfs is called
back via issue_op() to obtain the data from the server.  Once
the read completes, the netfs must call netfs_subreq_terminated()
which then may write the data to fscache.  In order to call back
into fscache via netfs_subreq_terminated(), we must save the
netfs_read_subrequest* as a field in the nfs_pgio_header, similar
to nfs_direct_req.

If the netfs has a read IO limit (for example, NFS 'rsize' mount
options) the clamp_length() function is called.

Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
---

 fs/nfs/fscache.c         |  157 ++++++++++++++++++++++++++++++----------------
 fs/nfs/fscache.h         |   38 +++++------
 fs/nfs/pagelist.c        |    2 +
 fs/nfs/read.c            |    9 ++-
 include/linux/nfs_page.h |    1 
 include/linux/nfs_xdr.h  |    1 
 6 files changed, 131 insertions(+), 77 deletions(-)

diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index a60df88efc40..d3445bb1cc9c 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -15,6 +15,9 @@
 #include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <linux/iversion.h>
+#include <linux/xarray.h>
+#include <linux/fscache.h>
+#include <linux/netfs.h>
 
 #include "internal.h"
 #include "iostat.h"
@@ -373,66 +376,123 @@ void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
 			      NFSIOS_FSCACHE_PAGES_UNCACHED);
 }
 
-/*
- * Handle completion of a page being read from the cache.
- * - Called in process (keventd) context.
- */
-static void nfs_readpage_from_fscache_complete(struct page *page,
-					       void *context,
-					       int error)
+static void nfs_issue_op(struct netfs_read_subrequest *subreq)
 {
-	dfprintk(FSCACHE,
-		 "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
-		 page, context, error);
-
-	/* if the read completes with an error, we just unlock the page and let
-	 * the VM reissue the readpage */
-	if (!error) {
-		SetPageUptodate(page);
-		unlock_page(page);
-	} else {
-		error = nfs_readpage_async(context, page->mapping->host, page);
-		if (error)
-			unlock_page(page);
+	struct inode *inode = subreq->rreq->inode;
+	struct nfs_readdesc *desc = subreq->rreq->netfs_priv;
+	struct page *page;
+	pgoff_t start = (subreq->start + subreq->transferred) >> PAGE_SHIFT;
+	pgoff_t last = ((subreq->start + subreq->len -
+			 subreq->transferred - 1) >> PAGE_SHIFT);
+	XA_STATE(xas, &subreq->rreq->mapping->i_pages, start);
+
+	dfprintk(FSCACHE, "NFS: %s(fsc:%p s:%lu l:%lu) subreq->start: %lld "
+		 "subreq->len: %ld subreq->transferred: %ld\n",
+		 __func__, nfs_i_fscache(inode), start, last, subreq->start,
+		 subreq->len, subreq->transferred);
+
+	nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
+			      last - start + 1);
+	nfs_pageio_init_read(&desc->pgio, inode, false,
+			     &nfs_async_read_completion_ops);
+
+	desc->pgio.pg_fsc = subreq; /* used in completion */
+
+	rcu_read_lock();
+	xas_for_each(&xas, page, last) {
+		subreq->error = readpage_async_filler(desc, page);
+		if (subreq->error < 0)
+			break;
+	}
+	rcu_read_unlock();
+	nfs_pageio_complete_read(&desc->pgio, inode);
+}
+
+static bool nfs_clamp_length(struct netfs_read_subrequest *subreq)
+{
+	struct inode *inode = subreq->rreq->mapping->host;
+	unsigned int rsize = NFS_SB(inode->i_sb)->rsize;
+
+	if (subreq->len > rsize) {
+		dfprintk(FSCACHE,
+			 "NFS: %s(fsc:%p slen:%lu rsize: %u)\n",
+			 __func__, nfs_i_fscache(inode), subreq->len, rsize);
+		subreq->len = rsize;
 	}
+
+	return true;
+}
+
+static void nfs_cleanup(struct address_space *mapping, void *netfs_priv)
+{
+	; /* fscache assumes if netfs_priv is given we have cleanup */
+}
+
+atomic_t nfs_fscache_debug_id;
+static void nfs_init_rreq(struct netfs_read_request *rreq, struct file *file)
+{
+	struct nfs_inode *nfsi = NFS_I(rreq->inode);
+
+	if (nfsi->fscache && test_bit(NFS_INO_FSCACHE, &nfsi->flags))
+		rreq->cookie_debug_id = atomic_inc_return(&nfs_fscache_debug_id);
+}
+
+static bool nfs_is_cache_enabled(struct inode *inode)
+{
+	struct nfs_inode *nfsi = NFS_I(inode);
+
+	return nfsi->fscache && test_bit(NFS_INO_FSCACHE, &nfsi->flags);
+}
+
+static int nfs_begin_cache_operation(struct netfs_read_request *rreq)
+{
+	struct fscache_cookie *cookie = NFS_I(rreq->inode)->fscache;
+
+	return fscache_begin_read_operation(rreq, cookie);
 }
 
+static struct netfs_read_request_ops nfs_fscache_req_ops = {
+	.init_rreq		= nfs_init_rreq,
+	.is_cache_enabled	= nfs_is_cache_enabled,
+	.begin_cache_operation	= nfs_begin_cache_operation,
+	.issue_op		= nfs_issue_op,
+	.clamp_length		= nfs_clamp_length,
+	.cleanup		= nfs_cleanup
+};
+
 /*
  * Retrieve a page from fscache
  */
-int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
-				struct inode *inode, struct page *page)
+int __nfs_readpage_from_fscache(struct file *filp,
+				struct page *page,
+				struct nfs_readdesc *desc)
 {
 	int ret;
+	struct inode *inode = file_inode(filp);
 
 	dfprintk(FSCACHE,
 		 "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
 		 nfs_i_fscache(inode), page, page->index, page->flags, inode);
 
-	ret = fscache_read_or_alloc_page(nfs_i_fscache(inode),
-					 page,
-					 nfs_readpage_from_fscache_complete,
-					 ctx,
-					 GFP_KERNEL);
+	ret = netfs_readpage(filp, page, &nfs_fscache_req_ops, desc);
 
 	switch (ret) {
-	case 0: /* read BIO submitted (page in fscache) */
-		dfprintk(FSCACHE,
-			 "NFS:    readpage_from_fscache: BIO submitted\n");
+	case 0: /* read submitted */
+		dfprintk(FSCACHE, "NFS:    readpage_from_fscache: submitted\n");
 		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
 		return ret;
 
 	case -ENOBUFS: /* inode not in cache */
 	case -ENODATA: /* page not in cache */
 		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
-		dfprintk(FSCACHE,
-			 "NFS:    readpage_from_fscache %d\n", ret);
+		dfprintk(FSCACHE, "NFS:    readpage_from_fscache %d\n", ret);
 		return 1;
 
 	default:
 		dfprintk(FSCACHE, "NFS:    readpage_from_fscache %d\n", ret);
 		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
 	}
+
 	return ret;
 }
 
@@ -487,30 +547,19 @@ int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
 }
 
 /*
- * Store a newly fetched page in fscache
- * - PG_fscache must be set on the page
+ * Store a newly fetched data in fscache
  */
-void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
+void __nfs_read_completion_to_fscache(struct nfs_pgio_header *hdr,
+				      unsigned long bytes)
 {
-	int ret;
+	struct netfs_read_subrequest *subreq = hdr->fsc;
 
-	dfprintk(FSCACHE,
-		 "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
-		 nfs_i_fscache(inode), page, page->index, page->flags, sync);
-
-	ret = fscache_write_page(nfs_i_fscache(inode), page,
-				 inode->i_size, GFP_KERNEL);
-	dfprintk(FSCACHE,
-		 "NFS:     readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
-		 page, page->index, page->flags, ret);
-
-	if (ret != 0) {
-		fscache_uncache_page(nfs_i_fscache(inode), page);
-		nfs_inc_fscache_stats(inode,
-				      NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
-		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
-	} else {
-		nfs_inc_fscache_stats(inode,
-				      NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
+	if (subreq) {
+		dfprintk(FSCACHE,
+			 "NFS: read_completion_to_fscache(fsc:%p err:%d bytes:%lu subreq->len:%lu\n",
+			 NFS_I(hdr->inode)->fscache, hdr->error, bytes, subreq->len);
+		__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
+		netfs_subreq_terminated(subreq, hdr->error ?: bytes);
+		hdr->fsc = NULL;
 	}
 }
diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
index 6754c8607230..4a76a5f31772 100644
--- a/fs/nfs/fscache.h
+++ b/fs/nfs/fscache.h
@@ -95,9 +95,9 @@ extern void nfs_fscache_open_file(struct inode *, struct file *);
 
 extern void __nfs_fscache_invalidate_page(struct page *, struct inode *);
 extern int nfs_fscache_release_page(struct page *, gfp_t);
-
-extern int __nfs_readpage_from_fscache(struct nfs_open_context *,
-				       struct inode *, struct page *);
+extern int __nfs_readpage_from_fscache(struct file *filp,
+				       struct page *page,
+				       struct nfs_readdesc *desc);
 extern int __nfs_readpages_from_fscache(struct nfs_open_context *,
 					struct inode *, struct address_space *,
 					struct list_head *, unsigned *);
@@ -127,12 +127,12 @@ static inline void nfs_fscache_invalidate_page(struct page *page,
 /*
  * Retrieve a page from an inode data storage object.
  */
-static inline int nfs_readpage_from_fscache(struct nfs_open_context *ctx,
-					    struct inode *inode,
-					    struct page *page)
+static inline int nfs_readpage_from_fscache(struct file *filp,
+					    struct page *page,
+					    struct nfs_readdesc *desc)
 {
-	if (NFS_I(inode)->fscache)
-		return __nfs_readpage_from_fscache(ctx, inode, page);
+	if (NFS_I(file_inode(filp))->fscache)
+		return __nfs_readpage_from_fscache(filp, page, desc);
 	return -ENOBUFS;
 }
 
@@ -152,15 +152,14 @@ static inline int nfs_readpages_from_fscache(struct nfs_open_context *ctx,
 }
 
 /*
- * Store a page newly fetched from the server in an inode data storage object
+ * Store pages newly fetched from the server in an inode data storage object
  * in the cache.
  */
-static inline void nfs_readpage_to_fscache(struct inode *inode,
-					   struct page *page,
-					   int sync)
+static inline void nfs_read_completion_to_fscache(struct nfs_pgio_header *hdr,
+						  unsigned long bytes)
 {
-	if (PageFsCache(page))
-		__nfs_readpage_to_fscache(inode, page, sync);
+	if (NFS_I(hdr->inode)->fscache)
+		__nfs_read_completion_to_fscache(hdr, bytes);
 }
 
 /*
@@ -212,9 +211,9 @@ static inline void nfs_fscache_invalidate_page(struct page *page,
 static inline void nfs_fscache_wait_on_page_write(struct nfs_inode *nfsi,
 						  struct page *page) {}
 
-static inline int nfs_readpage_from_fscache(struct nfs_open_context *ctx,
-					    struct inode *inode,
-					    struct page *page)
+static inline int nfs_readpage_from_fscache(struct file *filp,
+					    struct page *page,
+					    struct nfs_readdesc *desc)
 {
 	return -ENOBUFS;
 }
@@ -226,9 +225,8 @@ static inline int nfs_readpages_from_fscache(struct nfs_open_context *ctx,
 {
 	return -ENOBUFS;
 }
-static inline void nfs_readpage_to_fscache(struct inode *inode,
-					   struct page *page, int sync) {}
-
+static inline void nfs_read_completion_to_fscache(struct nfs_pgio_header *hdr,
+						  unsigned long bytes) {}
 
 static inline void nfs_fscache_invalidate(struct inode *inode) {}
 static inline void nfs_fscache_wait_on_invalidate(struct inode *inode) {}
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 78c9c4bdef2b..2e21e6c4023a 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -68,6 +68,7 @@ void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
 	hdr->good_bytes = mirror->pg_count;
 	hdr->io_completion = desc->pg_io_completion;
 	hdr->dreq = desc->pg_dreq;
+	hdr->fsc = desc->pg_fsc;
 	hdr->release = release;
 	hdr->completion_ops = desc->pg_completion_ops;
 	if (hdr->completion_ops->init_hdr)
@@ -849,6 +850,7 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 	desc->pg_lseg = NULL;
 	desc->pg_io_completion = NULL;
 	desc->pg_dreq = NULL;
+	desc->pg_fsc = NULL;
 	desc->pg_bsize = bsize;
 
 	desc->pg_mirror_count = 1;
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 13266eda8f60..7a76ab474fe0 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -124,10 +124,11 @@ static void nfs_readpage_release(struct nfs_page *req, int error)
 		struct address_space *mapping = page_file_mapping(page);
 
 		if (PageUptodate(page))
-			nfs_readpage_to_fscache(inode, page, 0);
+			; /* FIXME: review fscache page error handling */
 		else if (!PageError(page) && !PagePrivate(page))
 			generic_error_remove_page(mapping, page);
-		unlock_page(page);
+		if (!nfs_i_fscache(inode))
+			unlock_page(page);
 	}
 	nfs_release_request(req);
 }
@@ -181,6 +182,8 @@ static void nfs_read_completion(struct nfs_pgio_header *hdr)
 		nfs_list_remove_request(req);
 		nfs_readpage_release(req, error);
 	}
+	/* FIXME: NFS_IOHDR_ERROR and NFS_IOHDR_EOF handled per-page */
+	nfs_read_completion_to_fscache(hdr, bytes);
 out:
 	hdr->release(hdr);
 }
@@ -359,7 +362,7 @@ int nfs_readpage(struct file *filp, struct page *page)
 		desc.ctx = get_nfs_open_context(nfs_file_open_context(filp));
 
 	if (!IS_SYNC(inode)) {
-		ret = nfs_readpage_from_fscache(desc.ctx, inode, page);
+		ret = nfs_readpage_from_fscache(filp, page, &desc);
 		if (ret == 0)
 			goto out;
 	}
diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
index f0373a6cb5fb..b45570bcde91 100644
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -101,6 +101,7 @@ struct nfs_pageio_descriptor {
 	struct pnfs_layout_segment *pg_lseg;
 	struct nfs_io_completion *pg_io_completion;
 	struct nfs_direct_req	*pg_dreq;
+	void			*pg_fsc;
 	unsigned int		pg_bsize;	/* default bsize for mirrors */
 
 	u32			pg_mirror_count;
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 3327239fa2f9..95423d3d9d98 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1607,6 +1607,7 @@ struct nfs_pgio_header {
 	const struct nfs_rw_ops	*rw_ops;
 	struct nfs_io_completion *io_completion;
 	struct nfs_direct_req	*dreq;
+	void			*fsc;
 
 	int			pnfs_error;
 	int			error;		/* merge with pnfs_error */



^ permalink raw reply	[flat|nested] 41+ messages in thread

* [PATCH 32/32] NFS: Convert readpage to readahead and use netfs_readahead for fscache
  2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
                   ` (30 preceding siblings ...)
  2021-01-25 21:37 ` [PATCH 31/32] NFS: Convert to the netfs API and nfs_readpage to use netfs_readpage David Howells
@ 2021-01-25 21:37 ` David Howells
  2021-01-26  1:36   ` Matthew Wilcox
  31 siblings, 1 reply; 41+ messages in thread
From: David Howells @ 2021-01-25 21:37 UTC (permalink / raw)
  To: Trond Myklebust, Anna Schumaker, Steve French, Dominique Martinet
  Cc: Dave Wysochanski, dhowells, Jeff Layton, David Wysochanski,
	Matthew Wilcox, Alexander Viro, linux-cachefs, linux-afs,
	linux-nfs, linux-cifs, ceph-devel, v9fs-developer, linux-fsdevel,
	linux-kernel

From: Dave Wysochanski <dwysocha@redhat.com>

The new FS-Cache API does not have a readpages equivalent function,
and instead of fscache_read_or_alloc_pages() it implements a readahead
function, netfs_readahead().  Call netfs_readahead() if fscache is
enabled, and if not, utilize readahead_page() to run through the
pages needed calling readpage_async_filler().

Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
---

 fs/nfs/file.c              |    2 +-
 fs/nfs/fscache.c           |   49 +++++++-------------------------------------
 fs/nfs/fscache.h           |   28 +++++++++----------------
 fs/nfs/read.c              |   32 ++++++++++++++---------------
 include/linux/nfs_fs.h     |    3 +--
 include/linux/nfs_iostat.h |    2 +-
 6 files changed, 37 insertions(+), 79 deletions(-)

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 63940a7a70be..ebcaa164db5f 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -515,7 +515,7 @@ static void nfs_swap_deactivate(struct file *file)
 
 const struct address_space_operations nfs_file_aops = {
 	.readpage = nfs_readpage,
-	.readpages = nfs_readpages,
+	.readahead = nfs_readahead,
 	.set_page_dirty = __set_page_dirty_nobuffers,
 	.writepage = nfs_writepage,
 	.writepages = nfs_writepages,
diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index d3445bb1cc9c..b432bf931470 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -499,51 +499,18 @@ int __nfs_readpage_from_fscache(struct file *filp,
 /*
  * Retrieve a set of pages from fscache
  */
-int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
-				 struct inode *inode,
-				 struct address_space *mapping,
-				 struct list_head *pages,
-				 unsigned *nr_pages)
+int __nfs_readahead_from_fscache(struct nfs_readdesc *desc,
+				 struct readahead_control *rac)
 {
-	unsigned npages = *nr_pages;
-	int ret;
+	struct inode *inode = rac->mapping->host;
 
-	dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
-		 nfs_i_fscache(inode), npages, inode);
-
-	ret = fscache_read_or_alloc_pages(nfs_i_fscache(inode),
-					  mapping, pages, nr_pages,
-					  nfs_readpage_from_fscache_complete,
-					  ctx,
-					  mapping_gfp_mask(mapping));
-	if (*nr_pages < npages)
-		nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
-				      npages);
-	if (*nr_pages > 0)
-		nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
-				      *nr_pages);
+	dfprintk(FSCACHE, "NFS: nfs_readahead_from_fscache (0x%p/0x%p)\n",
+		 nfs_i_fscache(inode), inode);
 
-	switch (ret) {
-	case 0: /* read submitted to the cache for all pages */
-		BUG_ON(!list_empty(pages));
-		BUG_ON(*nr_pages != 0);
-		dfprintk(FSCACHE,
-			 "NFS: nfs_getpages_from_fscache: submitted\n");
+	netfs_readahead(rac, &nfs_fscache_req_ops, desc);
 
-		return ret;
-
-	case -ENOBUFS: /* some pages aren't cached and can't be */
-	case -ENODATA: /* some pages aren't cached */
-		dfprintk(FSCACHE,
-			 "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
-		return 1;
-
-	default:
-		dfprintk(FSCACHE,
-			 "NFS: nfs_getpages_from_fscache: ret  %d\n", ret);
-	}
-
-	return ret;
+	/* FIXME: NFSIOS_NFSIOS_FSCACHE_ stats */
+	return 0;
 }
 
 /*
diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
index 4a76a5f31772..d095e513af12 100644
--- a/fs/nfs/fscache.h
+++ b/fs/nfs/fscache.h
@@ -98,11 +98,10 @@ extern int nfs_fscache_release_page(struct page *, gfp_t);
 extern int __nfs_readpage_from_fscache(struct file *filp,
 				       struct page *page,
 				       struct nfs_readdesc *desc);
-extern int __nfs_readpages_from_fscache(struct nfs_open_context *,
-					struct inode *, struct address_space *,
-					struct list_head *, unsigned *);
-extern void __nfs_readpage_to_fscache(struct inode *, struct page *, int);
-
+extern int __nfs_readahead_from_fscache(struct nfs_readdesc *desc,
+					struct readahead_control *rac);
+extern void __nfs_read_completion_to_fscache(struct nfs_pgio_header *hdr,
+					     unsigned long bytes);
 /*
  * wait for a page to complete writing to the cache
  */
@@ -139,15 +138,11 @@ static inline int nfs_readpage_from_fscache(struct file *filp,
 /*
  * Retrieve a set of pages from an inode data storage object.
  */
-static inline int nfs_readpages_from_fscache(struct nfs_open_context *ctx,
-					     struct inode *inode,
-					     struct address_space *mapping,
-					     struct list_head *pages,
-					     unsigned *nr_pages)
+static inline int nfs_readahead_from_fscache(struct nfs_readdesc *desc,
+					     struct readahead_control *rac)
 {
-	if (NFS_I(inode)->fscache)
-		return __nfs_readpages_from_fscache(ctx, inode, mapping, pages,
-						    nr_pages);
+	if (NFS_I(rac->mapping->host)->fscache)
+		return __nfs_readahead_from_fscache(desc, rac);
 	return -ENOBUFS;
 }
 
@@ -217,11 +212,8 @@ static inline int nfs_readpage_from_fscache(struct file *filp,
 {
 	return -ENOBUFS;
 }
-static inline int nfs_readpages_from_fscache(struct nfs_open_context *ctx,
-					     struct inode *inode,
-					     struct address_space *mapping,
-					     struct list_head *pages,
-					     unsigned *nr_pages)
+static inline int nfs_readahead_from_fscache(struct nfs_readdesc *desc,
+					     struct readahead_control *rac)
 {
 	return -ENOBUFS;
 }
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 7a76ab474fe0..da44ce68488c 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -390,50 +390,50 @@ int nfs_readpage(struct file *filp, struct page *page)
 	return ret;
 }
 
-int nfs_readpages(struct file *filp, struct address_space *mapping,
-		struct list_head *pages, unsigned nr_pages)
+void nfs_readahead(struct readahead_control *rac)
 {
 	struct nfs_readdesc desc;
-	struct inode *inode = mapping->host;
+	struct inode *inode = rac->mapping->host;
+	struct page *page;
 	int ret;
 
-	dprintk("NFS: nfs_readpages (%s/%Lu %d)\n",
-			inode->i_sb->s_id,
-			(unsigned long long)NFS_FILEID(inode),
-			nr_pages);
+	dprintk("NFS: %s (%s/%llu %lld)\n", __func__,
+		inode->i_sb->s_id,
+		(unsigned long long)NFS_FILEID(inode),
+		readahead_length(rac));
 	nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
 
 	ret = -ESTALE;
 	if (NFS_STALE(inode))
-		goto out;
+		return;
 
-	if (filp == NULL) {
+	if (rac->file == NULL) {
 		ret = -EBADF;
 		desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
 		if (desc.ctx == NULL)
-			goto out;
+			return;
 	} else
-		desc.ctx = get_nfs_open_context(nfs_file_open_context(filp));
+		desc.ctx = get_nfs_open_context(nfs_file_open_context(rac->file));
 
 	/* attempt to read as many of the pages as possible from the cache
 	 * - this returns -ENOBUFS immediately if the cookie is negative
 	 */
-	ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping,
-					 pages, &nr_pages);
+	ret = nfs_readahead_from_fscache(&desc, rac);
 	if (ret == 0)
 		goto read_complete; /* all pages were read */
 
 	nfs_pageio_init_read(&desc.pgio, inode, false,
 			     &nfs_async_read_completion_ops);
 
-	ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
+	while ((page = readahead_page(rac))) {
+		ret = readpage_async_filler(&desc, page);
+		put_page(page);
+	}
 
 	nfs_pageio_complete_read(&desc.pgio, inode);
 
 read_complete:
 	put_nfs_open_context(desc.ctx);
-out:
-	return ret;
 }
 
 int __init nfs_init_readpagecache(void)
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 3cfcf219e96b..968c79b1b09b 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -568,8 +568,7 @@ nfs_have_writebacks(struct inode *inode)
  * linux/fs/nfs/read.c
  */
 extern int  nfs_readpage(struct file *, struct page *);
-extern int  nfs_readpages(struct file *, struct address_space *,
-		struct list_head *, unsigned);
+extern void nfs_readahead(struct readahead_control *rac);
 
 /*
  * inline functions
diff --git a/include/linux/nfs_iostat.h b/include/linux/nfs_iostat.h
index 027874c36c88..8baf8fb7551d 100644
--- a/include/linux/nfs_iostat.h
+++ b/include/linux/nfs_iostat.h
@@ -53,7 +53,7 @@
  * NFS page counters
  *
  * These count the number of pages read or written via nfs_readpage(),
- * nfs_readpages(), or their write equivalents.
+ * nfs_readahead(), or their write equivalents.
  *
  * NB: When adding new byte counters, please include the measured
  * units in the name of each byte counter to help users of this



^ permalink raw reply	[flat|nested] 41+ messages in thread

* Re: [PATCH 32/32] NFS: Convert readpage to readahead and use netfs_readahead for fscache
  2021-01-25 21:37 ` [PATCH 32/32] NFS: Convert readpage to readahead and use netfs_readahead for fscache David Howells
@ 2021-01-26  1:36   ` Matthew Wilcox
  2021-01-26 15:24     ` Chuck Lever
  2021-01-26 18:25     ` David Wysochanski
  0 siblings, 2 replies; 41+ messages in thread
From: Matthew Wilcox @ 2021-01-26  1:36 UTC (permalink / raw)
  To: David Howells
  Cc: Trond Myklebust, Anna Schumaker, Steve French,
	Dominique Martinet, Dave Wysochanski, Jeff Layton,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel


For Subject: s/readpage/readpages/

On Mon, Jan 25, 2021 at 09:37:29PM +0000, David Howells wrote:
> +int __nfs_readahead_from_fscache(struct nfs_readdesc *desc,
> +				 struct readahead_control *rac)

I thought you wanted it called ractl instead of rac?  That's what I've
been using in new code.

> -	dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
> -		 nfs_i_fscache(inode), npages, inode);
> +	dfprintk(FSCACHE, "NFS: nfs_readahead_from_fscache (0x%p/0x%p)\n",
> +		 nfs_i_fscache(inode), inode);

We do have readahead_count() if this is useful information to be logging.

> +static inline int nfs_readahead_from_fscache(struct nfs_readdesc *desc,
> +					     struct readahead_control *rac)
>  {
> -	if (NFS_I(inode)->fscache)
> -		return __nfs_readpages_from_fscache(ctx, inode, mapping, pages,
> -						    nr_pages);
> +	if (NFS_I(rac->mapping->host)->fscache)
> +		return __nfs_readahead_from_fscache(desc, rac);
>  	return -ENOBUFS;
>  }

Not entirely sure that it's worth having the two functions separated any more.

>  	/* attempt to read as many of the pages as possible from the cache
>  	 * - this returns -ENOBUFS immediately if the cookie is negative
>  	 */
> -	ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping,
> -					 pages, &nr_pages);
> +	ret = nfs_readahead_from_fscache(&desc, rac);
>  	if (ret == 0)
>  		goto read_complete; /* all pages were read */
>  
>  	nfs_pageio_init_read(&desc.pgio, inode, false,
>  			     &nfs_async_read_completion_ops);
>  
> -	ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
> +	while ((page = readahead_page(rac))) {
> +		ret = readpage_async_filler(&desc, page);
> +		put_page(page);
> +	}

I thought with the new API we didn't need to do this kind of thing
any more?  ie no matter whether fscache is configured in or not, it'll
submit the I/Os.

^ permalink raw reply	[flat|nested] 41+ messages in thread

* Re: [PATCH 25/32] NFS: Clean up nfs_readpage() and nfs_readpages()
  2021-01-25 21:35 ` [PATCH 25/32] NFS: Clean up nfs_readpage() and nfs_readpages() David Howells
@ 2021-01-26  3:59   ` Matthew Wilcox
  2021-01-26 15:33     ` David Wysochanski
  0 siblings, 1 reply; 41+ messages in thread
From: Matthew Wilcox @ 2021-01-26  3:59 UTC (permalink / raw)
  To: David Howells
  Cc: Trond Myklebust, Anna Schumaker, Steve French,
	Dominique Martinet, Dave Wysochanski, Jeff Layton,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

On Mon, Jan 25, 2021 at 09:35:49PM +0000, David Howells wrote:
> -int nfs_readpage(struct file *file, struct page *page)
> +int nfs_readpage(struct file *filp, struct page *page)

I appreciate we're inconsistent between file and filp, but we're actually
moving more towards file than filp.


^ permalink raw reply	[flat|nested] 41+ messages in thread

* Re: [PATCH 27/32] NFS: Refactor nfs_readpage() and nfs_readpage_async() to use nfs_readdesc
  2021-01-25 21:36 ` [PATCH 27/32] NFS: Refactor nfs_readpage() and nfs_readpage_async() to use nfs_readdesc David Howells
@ 2021-01-26  4:05   ` Matthew Wilcox
  2021-01-26 15:24     ` David Wysochanski
  0 siblings, 1 reply; 41+ messages in thread
From: Matthew Wilcox @ 2021-01-26  4:05 UTC (permalink / raw)
  To: David Howells
  Cc: Trond Myklebust, Anna Schumaker, Steve French,
	Dominique Martinet, Dave Wysochanski, Jeff Layton,
	Alexander Viro, linux-cachefs, linux-afs, linux-nfs, linux-cifs,
	ceph-devel, v9fs-developer, linux-fsdevel, linux-kernel

On Mon, Jan 25, 2021 at 09:36:13PM +0000, David Howells wrote:
> +int nfs_readpage_async(void *data, struct inode *inode,
>  		       struct page *page)
>  {
> +	struct nfs_readdesc *desc = (struct nfs_readdesc *)data;

You don't need a cast to cast from void.

> @@ -440,17 +439,16 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
>  	if (ret == 0)
>  		goto read_complete; /* all pages were read */
>  
> -	desc.pgio = &pgio;
> -	nfs_pageio_init_read(&pgio, inode, false,
> +	nfs_pageio_init_read(&desc.pgio, inode, false,

I like what you've done here, embedding the pgio in the desc.


^ permalink raw reply	[flat|nested] 41+ messages in thread

* Re: [PATCH 32/32] NFS: Convert readpage to readahead and use netfs_readahead for fscache
  2021-01-26  1:36   ` Matthew Wilcox
@ 2021-01-26 15:24     ` Chuck Lever
  2021-01-26 19:10       ` David Wysochanski
  2021-01-26 18:25     ` David Wysochanski
  1 sibling, 1 reply; 41+ messages in thread
From: Chuck Lever @ 2021-01-26 15:24 UTC (permalink / raw)
  To: Matthew Wilcox, David Howells, Dave Wysochanski
  Cc: Trond Myklebust, Anna Schumaker, Steve French,
	Dominique Martinet, Jeff Layton, Al Viro, linux-cachefs,
	linux-afs, Linux NFS Mailing List, CIFS, ceph-devel,
	v9fs-developer, linux-fsdevel, Linux Kernel Mailing List



> On Jan 25, 2021, at 8:36 PM, Matthew Wilcox <willy@infradead.org> wrote:
> 
> 
> For Subject: s/readpage/readpages/
> 
> On Mon, Jan 25, 2021 at 09:37:29PM +0000, David Howells wrote:
>> +int __nfs_readahead_from_fscache(struct nfs_readdesc *desc,
>> +				 struct readahead_control *rac)
> 
> I thought you wanted it called ractl instead of rac?  That's what I've
> been using in new code.
> 
>> -	dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
>> -		 nfs_i_fscache(inode), npages, inode);
>> +	dfprintk(FSCACHE, "NFS: nfs_readahead_from_fscache (0x%p/0x%p)\n",
>> +		 nfs_i_fscache(inode), inode);
> 
> We do have readahead_count() if this is useful information to be logging.

As a sidebar, the Linux NFS community is transitioning to tracepoints.
It would be helpful (but not completely necessary) to use tracepoints
in new code instead of printk.


>> +static inline int nfs_readahead_from_fscache(struct nfs_readdesc *desc,
>> +					     struct readahead_control *rac)
>> {
>> -	if (NFS_I(inode)->fscache)
>> -		return __nfs_readpages_from_fscache(ctx, inode, mapping, pages,
>> -						    nr_pages);
>> +	if (NFS_I(rac->mapping->host)->fscache)
>> +		return __nfs_readahead_from_fscache(desc, rac);
>> 	return -ENOBUFS;
>> }
> 
> Not entirely sure that it's worth having the two functions separated any more.
> 
>> 	/* attempt to read as many of the pages as possible from the cache
>> 	 * - this returns -ENOBUFS immediately if the cookie is negative
>> 	 */
>> -	ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping,
>> -					 pages, &nr_pages);
>> +	ret = nfs_readahead_from_fscache(&desc, rac);
>> 	if (ret == 0)
>> 		goto read_complete; /* all pages were read */
>> 
>> 	nfs_pageio_init_read(&desc.pgio, inode, false,
>> 			     &nfs_async_read_completion_ops);
>> 
>> -	ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
>> +	while ((page = readahead_page(rac))) {
>> +		ret = readpage_async_filler(&desc, page);
>> +		put_page(page);
>> +	}
> 
> I thought with the new API we didn't need to do this kind of thing
> any more?  ie no matter whether fscache is configured in or not, it'll
> submit the I/Os.

--
Chuck Lever




^ permalink raw reply	[flat|nested] 41+ messages in thread

* Re: [PATCH 27/32] NFS: Refactor nfs_readpage() and nfs_readpage_async() to use nfs_readdesc
  2021-01-26  4:05   ` Matthew Wilcox
@ 2021-01-26 15:24     ` David Wysochanski
  0 siblings, 0 replies; 41+ messages in thread
From: David Wysochanski @ 2021-01-26 15:24 UTC (permalink / raw)
  To: Matthew Wilcox
  Cc: David Howells, Trond Myklebust, Anna Schumaker, Steve French,
	Dominique Martinet, Jeff Layton, Alexander Viro, linux-cachefs,
	linux-afs, linux-nfs, linux-cifs, ceph-devel, v9fs-developer,
	linux-fsdevel, Linux Kernel Mailing List

On Mon, Jan 25, 2021 at 11:06 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Mon, Jan 25, 2021 at 09:36:13PM +0000, David Howells wrote:
> > +int nfs_readpage_async(void *data, struct inode *inode,
> >                      struct page *page)
> >  {
> > +     struct nfs_readdesc *desc = (struct nfs_readdesc *)data;
>
> You don't need a cast to cast from void.
>
Right, fixing.

> > @@ -440,17 +439,16 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
> >       if (ret == 0)
> >               goto read_complete; /* all pages were read */
> >
> > -     desc.pgio = &pgio;
> > -     nfs_pageio_init_read(&pgio, inode, false,
> > +     nfs_pageio_init_read(&desc.pgio, inode, false,
>
> I like what you've done here, embedding the pgio in the desc.
>
Thanks for the review!


^ permalink raw reply	[flat|nested] 41+ messages in thread

* Re: [PATCH 25/32] NFS: Clean up nfs_readpage() and nfs_readpages()
  2021-01-26  3:59   ` Matthew Wilcox
@ 2021-01-26 15:33     ` David Wysochanski
  0 siblings, 0 replies; 41+ messages in thread
From: David Wysochanski @ 2021-01-26 15:33 UTC (permalink / raw)
  To: Matthew Wilcox
  Cc: David Howells, Trond Myklebust, Anna Schumaker, Steve French,
	Dominique Martinet, Jeff Layton, Alexander Viro, linux-cachefs,
	linux-afs, linux-nfs, linux-cifs, ceph-devel, v9fs-developer,
	linux-fsdevel, Linux Kernel Mailing List

On Mon, Jan 25, 2021 at 11:01 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Mon, Jan 25, 2021 at 09:35:49PM +0000, David Howells wrote:
> > -int nfs_readpage(struct file *file, struct page *page)
> > +int nfs_readpage(struct file *filp, struct page *page)
>
> I appreciate we're inconsistent between file and filp, but we're actually
> moving more towards file than filp.
>
Got it, easy enough to change.


^ permalink raw reply	[flat|nested] 41+ messages in thread

* Re: [PATCH 32/32] NFS: Convert readpage to readahead and use netfs_readahead for fscache
  2021-01-26  1:36   ` Matthew Wilcox
  2021-01-26 15:24     ` Chuck Lever
@ 2021-01-26 18:25     ` David Wysochanski
  1 sibling, 0 replies; 41+ messages in thread
From: David Wysochanski @ 2021-01-26 18:25 UTC (permalink / raw)
  To: Matthew Wilcox
  Cc: David Howells, Trond Myklebust, Anna Schumaker, Steve French,
	Dominique Martinet, Jeff Layton, Alexander Viro, linux-cachefs,
	linux-afs, linux-nfs, linux-cifs, ceph-devel, v9fs-developer,
	linux-fsdevel, Linux Kernel Mailing List

On Mon, Jan 25, 2021 at 8:37 PM Matthew Wilcox <willy@infradead.org> wrote:
>
>
> For Subject: s/readpage/readpages/
>
Fixed

> On Mon, Jan 25, 2021 at 09:37:29PM +0000, David Howells wrote:
> > +int __nfs_readahead_from_fscache(struct nfs_readdesc *desc,
> > +                              struct readahead_control *rac)
>
> I thought you wanted it called ractl instead of rac?  That's what I've
> been using in new code.
>
Fixed

> > -     dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
> > -              nfs_i_fscache(inode), npages, inode);
> > +     dfprintk(FSCACHE, "NFS: nfs_readahead_from_fscache (0x%p/0x%p)\n",
> > +              nfs_i_fscache(inode), inode);
>
> We do have readahead_count() if this is useful information to be logging.
>
Right, I used it elsewhere so I'll add here as well.

> > +static inline int nfs_readahead_from_fscache(struct nfs_readdesc *desc,
> > +                                          struct readahead_control *rac)
> >  {
> > -     if (NFS_I(inode)->fscache)
> > -             return __nfs_readpages_from_fscache(ctx, inode, mapping, pages,
> > -                                                 nr_pages);
> > +     if (NFS_I(rac->mapping->host)->fscache)
> > +             return __nfs_readahead_from_fscache(desc, rac);
> >       return -ENOBUFS;
> >  }
>
> Not entirely sure that it's worth having the two functions separated any more.
>
Yeah it's questionable so I'll collapse.  I'll also do that with
nfs_readpage_from_fscache().

> >       /* attempt to read as many of the pages as possible from the cache
> >        * - this returns -ENOBUFS immediately if the cookie is negative
> >        */
> > -     ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping,
> > -                                      pages, &nr_pages);
> > +     ret = nfs_readahead_from_fscache(&desc, rac);
> >       if (ret == 0)
> >               goto read_complete; /* all pages were read */
> >
> >       nfs_pageio_init_read(&desc.pgio, inode, false,
> >                            &nfs_async_read_completion_ops);
> >
> > -     ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
> > +     while ((page = readahead_page(rac))) {
> > +             ret = readpage_async_filler(&desc, page);
> > +             put_page(page);
> > +     }
>
> I thought with the new API we didn't need to do this kind of thing
> any more?  ie no matter whether fscache is configured in or not, it'll
> submit the I/Os.
>

We don't. This patchset was only intended as a stepping stone to get the
netfs API accepted with minimal invasiveness in NFS.

I have another patch which will unconditionally call netfs API but I
didn't post it. Since I'm not an NFS maintainer, and maintainer's didn't
weigh in on the approach, I opted to go with the least invasive approach.

There's an NFS "remote bakeathon" coming up at the end of Feb.
That would probably be a good time to get further testing on NFS
unconditionally calling the netfs API, and we should be able to
cover things like any performance concerns, etc.


^ permalink raw reply	[flat|nested] 41+ messages in thread

* Re: [PATCH 32/32] NFS: Convert readpage to readahead and use netfs_readahead for fscache
  2021-01-26 15:24     ` Chuck Lever
@ 2021-01-26 19:10       ` David Wysochanski
  0 siblings, 0 replies; 41+ messages in thread
From: David Wysochanski @ 2021-01-26 19:10 UTC (permalink / raw)
  To: Chuck Lever
  Cc: Matthew Wilcox, David Howells, Trond Myklebust, Anna Schumaker,
	Steve French, Dominique Martinet, Jeff Layton, Al Viro,
	linux-cachefs, linux-afs, Linux NFS Mailing List, CIFS,
	ceph-devel, v9fs-developer, linux-fsdevel,
	Linux Kernel Mailing List

On Tue, Jan 26, 2021 at 10:25 AM Chuck Lever <chuck.lever@oracle.com> wrote:
>
>
>
> > On Jan 25, 2021, at 8:36 PM, Matthew Wilcox <willy@infradead.org> wrote:
> >
> >
> > For Subject: s/readpage/readpages/
> >
> > On Mon, Jan 25, 2021 at 09:37:29PM +0000, David Howells wrote:
> >> +int __nfs_readahead_from_fscache(struct nfs_readdesc *desc,
> >> +                             struct readahead_control *rac)
> >
> > I thought you wanted it called ractl instead of rac?  That's what I've
> > been using in new code.
> >
> >> -    dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
> >> -             nfs_i_fscache(inode), npages, inode);
> >> +    dfprintk(FSCACHE, "NFS: nfs_readahead_from_fscache (0x%p/0x%p)\n",
> >> +             nfs_i_fscache(inode), inode);
> >
> > We do have readahead_count() if this is useful information to be logging.
>
> As a sidebar, the Linux NFS community is transitioning to tracepoints.
> It would be helpful (but not completely necessary) to use tracepoints
> in new code instead of printk.
>

The netfs API has a lot of good tracepoints and to be honest I think we can
get rid of fscache's rpcdebug, but let me take a closer look to be
sure.  I didn't use rpcdebug much, if at all, in the latest rounds of debugging.



>
> >> +static inline int nfs_readahead_from_fscache(struct nfs_readdesc *desc,
> >> +                                         struct readahead_control *rac)
> >> {
> >> -    if (NFS_I(inode)->fscache)
> >> -            return __nfs_readpages_from_fscache(ctx, inode, mapping, pages,
> >> -                                                nr_pages);
> >> +    if (NFS_I(rac->mapping->host)->fscache)
> >> +            return __nfs_readahead_from_fscache(desc, rac);
> >>      return -ENOBUFS;
> >> }
> >
> > Not entirely sure that it's worth having the two functions separated any more.
> >
> >>      /* attempt to read as many of the pages as possible from the cache
> >>       * - this returns -ENOBUFS immediately if the cookie is negative
> >>       */
> >> -    ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping,
> >> -                                     pages, &nr_pages);
> >> +    ret = nfs_readahead_from_fscache(&desc, rac);
> >>      if (ret == 0)
> >>              goto read_complete; /* all pages were read */
> >>
> >>      nfs_pageio_init_read(&desc.pgio, inode, false,
> >>                           &nfs_async_read_completion_ops);
> >>
> >> -    ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
> >> +    while ((page = readahead_page(rac))) {
> >> +            ret = readpage_async_filler(&desc, page);
> >> +            put_page(page);
> >> +    }
> >
> > I thought with the new API we didn't need to do this kind of thing
> > any more?  ie no matter whether fscache is configured in or not, it'll
> > submit the I/Os.
>
> --
> Chuck Lever
>
>
>


^ permalink raw reply	[flat|nested] 41+ messages in thread

end of thread, other threads:[~2021-01-27  7:32 UTC | newest]

Thread overview: 41+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-01-25 21:30 [PATCH 00/32] Network fs helper library & fscache kiocb API [ver #2] David Howells
2021-01-25 21:31 ` [PATCH 01/32] iov_iter: Add ITER_XARRAY David Howells
2021-01-25 21:31 ` [PATCH 02/32] vm: Add wait/unlock functions for PG_fscache David Howells
2021-01-25 21:31 ` [PATCH 03/32] mm: Implement readahead_control pageset expansion David Howells
2021-01-25 21:31 ` [PATCH 04/32] vfs: Export rw_verify_area() for use by cachefiles David Howells
2021-01-25 21:31 ` [PATCH 05/32] netfs: Make a netfs helper module David Howells
2021-01-25 21:32 ` [PATCH 06/32] netfs: Provide readahead and readpage netfs helpers David Howells
2021-01-25 21:32 ` [PATCH 07/32] netfs: Add tracepoints David Howells
2021-01-25 21:32 ` [PATCH 08/32] netfs: Gather stats David Howells
2021-01-25 21:32 ` [PATCH 09/32] netfs: Add write_begin helper David Howells
2021-01-25 21:32 ` [PATCH 10/32] netfs: Define an interface to talk to a cache David Howells
2021-01-25 21:32 ` [PATCH 11/32] fscache, cachefiles: Add alternate API to use kiocb for read/write to cache David Howells
2021-01-25 21:33 ` [PATCH 12/32] afs: Disable use of the fscache I/O routines David Howells
2021-01-25 21:33 ` [PATCH 13/32] afs: Pass page into dirty region helpers to provide THP size David Howells
2021-01-25 21:33 ` [PATCH 14/32] afs: Print the operation debug_id when logging an unexpected data version David Howells
2021-01-25 21:33 ` [PATCH 15/32] afs: Move key to afs_read struct David Howells
2021-01-25 21:34 ` [PATCH 16/32] afs: Don't truncate iter during data fetch David Howells
2021-01-25 21:34 ` [PATCH 17/32] afs: Log remote unmarshalling errors David Howells
2021-01-25 21:34 ` [PATCH 18/32] afs: Set up the iov_iter before calling afs_extract_data() David Howells
2021-01-25 21:34 ` [PATCH 19/32] afs: Use ITER_XARRAY for writing David Howells
2021-01-25 21:34 ` [PATCH 20/32] afs: Wait on PG_fscache before modifying/releasing a page David Howells
2021-01-25 21:35 ` [PATCH 21/32] afs: Extract writeback extension into its own function David Howells
2021-01-25 21:35 ` [PATCH 22/32] afs: Prepare for use of THPs David Howells
2021-01-25 21:35 ` [PATCH 23/32] afs: Use the fs operation ops to handle FetchData completion David Howells
2021-01-25 21:35 ` [PATCH 24/32] afs: Use new fscache read helper API David Howells
2021-01-25 21:35 ` [PATCH 25/32] NFS: Clean up nfs_readpage() and nfs_readpages() David Howells
2021-01-26  3:59   ` Matthew Wilcox
2021-01-26 15:33     ` David Wysochanski
2021-01-25 21:36 ` [PATCH 26/32] NFS: In nfs_readpage() only increment NFSIOS_READPAGES when read succeeds David Howells
2021-01-25 21:36 ` [PATCH 27/32] NFS: Refactor nfs_readpage() and nfs_readpage_async() to use nfs_readdesc David Howells
2021-01-26  4:05   ` Matthew Wilcox
2021-01-26 15:24     ` David Wysochanski
2021-01-25 21:36 ` [PATCH 28/32] NFS: Call readpage_async_filler() from nfs_readpage_async() David Howells
2021-01-25 21:36 ` [PATCH 29/32] NFS: Add nfs_pageio_complete_read() and remove nfs_readpage_async() David Howells
2021-01-25 21:37 ` [PATCH 30/32] NFS: Allow internal use of read structs and functions David Howells
2021-01-25 21:37 ` [PATCH 31/32] NFS: Convert to the netfs API and nfs_readpage to use netfs_readpage David Howells
2021-01-25 21:37 ` [PATCH 32/32] NFS: Convert readpage to readahead and use netfs_readahead for fscache David Howells
2021-01-26  1:36   ` Matthew Wilcox
2021-01-26 15:24     ` Chuck Lever
2021-01-26 19:10       ` David Wysochanski
2021-01-26 18:25     ` David Wysochanski

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