* [PATCH v2 0/5] block, dax: updates for 4.4
@ 2015-10-22 17:10 ` Dan Williams
0 siblings, 0 replies; 26+ messages in thread
From: Dan Williams @ 2015-10-22 17:10 UTC (permalink / raw)
To: axboe
Cc: Jens Axboe, Boaz Harrosh, jack, linux-nvdimm, Dave Hansen, david,
linux-kernel, hch, Jeff Moyer, Al Viro, Jan Kara, willy, akpm,
ross.zwisler
Changes since v1: https://lists.01.org/pipermail/linux-nvdimm/2015-October/002538.html
1/ Rename file_bd_inode to bdev_file_inode (Jan Kara)
2/ Clarify sb_start_pagefault() comment (Jan Kara)
3/ Collect Reviewed-by's
---
As requested [1], break out the block specific updates from the dax-gup
series [2], to merge via the block tree.
1/ Enable dax mappings for raw block devices. This addresses the review
comments (from Ross and Honza) from the RFC [3].
2/ Introduce dax_map_atomic() to fix races between device teardown and
new mapping requests. This depends on commit 2a9067a91825 "block:
generic request_queue reference counting" in for-4.4/integrity branch
of the block tree.
3/ Cleanup clear_pmem() and its usage in dax. This depends on commit
0f90cc6609c7 "mm, dax: fix DAX deadlocks" that was merged into v4.3-rc6.
These pass the nvdimm unit tests and have passed a 0day-kbuild-robot run.
[1]: https://lists.01.org/pipermail/linux-nvdimm/2015-October/002531.html
[2]: https://lists.01.org/pipermail/linux-nvdimm/2015-October/002387.html
[3]: https://lists.01.org/pipermail/linux-nvdimm/2015-October/002512.html
---
Dan Williams (5):
pmem, dax: clean up clear_pmem()
dax: increase granularity of dax_clear_blocks() operations
block, dax: fix lifetime of in-kernel dax mappings with dax_map_atomic()
block: introduce bdev_file_inode()
block: enable dax for raw block devices
arch/x86/include/asm/pmem.h | 7 --
block/blk.h | 2
fs/block_dev.c | 79 ++++++++++++++++-
fs/dax.c | 196 +++++++++++++++++++++++++++----------------
include/linux/blkdev.h | 2
5 files changed, 197 insertions(+), 89 deletions(-)
^ permalink raw reply [flat|nested] 26+ messages in thread
* [PATCH v2 0/5] block, dax: updates for 4.4
@ 2015-10-22 17:10 ` Dan Williams
0 siblings, 0 replies; 26+ messages in thread
From: Dan Williams @ 2015-10-22 17:10 UTC (permalink / raw)
To: axboe
Cc: Jens Axboe, Boaz Harrosh, jack, linux-nvdimm, Dave Hansen, david,
linux-kernel, hch, Jeff Moyer, Al Viro, Jan Kara, willy, akpm,
ross.zwisler
Changes since v1: https://lists.01.org/pipermail/linux-nvdimm/2015-October/002538.html
1/ Rename file_bd_inode to bdev_file_inode (Jan Kara)
2/ Clarify sb_start_pagefault() comment (Jan Kara)
3/ Collect Reviewed-by's
---
As requested [1], break out the block specific updates from the dax-gup
series [2], to merge via the block tree.
1/ Enable dax mappings for raw block devices. This addresses the review
comments (from Ross and Honza) from the RFC [3].
2/ Introduce dax_map_atomic() to fix races between device teardown and
new mapping requests. This depends on commit 2a9067a91825 "block:
generic request_queue reference counting" in for-4.4/integrity branch
of the block tree.
3/ Cleanup clear_pmem() and its usage in dax. This depends on commit
0f90cc6609c7 "mm, dax: fix DAX deadlocks" that was merged into v4.3-rc6.
These pass the nvdimm unit tests and have passed a 0day-kbuild-robot run.
[1]: https://lists.01.org/pipermail/linux-nvdimm/2015-October/002531.html
[2]: https://lists.01.org/pipermail/linux-nvdimm/2015-October/002387.html
[3]: https://lists.01.org/pipermail/linux-nvdimm/2015-October/002512.html
---
Dan Williams (5):
pmem, dax: clean up clear_pmem()
dax: increase granularity of dax_clear_blocks() operations
block, dax: fix lifetime of in-kernel dax mappings with dax_map_atomic()
block: introduce bdev_file_inode()
block: enable dax for raw block devices
arch/x86/include/asm/pmem.h | 7 --
block/blk.h | 2
fs/block_dev.c | 79 ++++++++++++++++-
fs/dax.c | 196 +++++++++++++++++++++++++++----------------
include/linux/blkdev.h | 2
5 files changed, 197 insertions(+), 89 deletions(-)
^ permalink raw reply [flat|nested] 26+ messages in thread
* [PATCH v2 1/5] pmem, dax: clean up clear_pmem()
2015-10-22 17:10 ` Dan Williams
@ 2015-10-22 17:10 ` Dan Williams
-1 siblings, 0 replies; 26+ messages in thread
From: Dan Williams @ 2015-10-22 17:10 UTC (permalink / raw)
To: axboe
Cc: jack, akpm, linux-nvdimm, Dave Hansen, david, linux-kernel,
willy, ross.zwisler, hch
Both, __dax_pmd_fault, and clear_pmem() were taking special steps to
clear memory a page at a time to take advantage of non-temporal
clear_page() implementations. However, x86_64 does not use
non-temporal instructions for clear_page(), and arch_clear_pmem() was
always incurring the cost of __arch_wb_cache_pmem().
Clean up the assumption that doing clear_pmem() a page at a time is more
performant.
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reported-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
arch/x86/include/asm/pmem.h | 7 +------
fs/dax.c | 4 +---
2 files changed, 2 insertions(+), 9 deletions(-)
diff --git a/arch/x86/include/asm/pmem.h b/arch/x86/include/asm/pmem.h
index d8ce3ec816ab..1544fabcd7f9 100644
--- a/arch/x86/include/asm/pmem.h
+++ b/arch/x86/include/asm/pmem.h
@@ -132,12 +132,7 @@ static inline void arch_clear_pmem(void __pmem *addr, size_t size)
{
void *vaddr = (void __force *)addr;
- /* TODO: implement the zeroing via non-temporal writes */
- if (size == PAGE_SIZE && ((unsigned long)vaddr & ~PAGE_MASK) == 0)
- clear_page(vaddr);
- else
- memset(vaddr, 0, size);
-
+ memset(vaddr, 0, size);
__arch_wb_cache_pmem(vaddr, size);
}
diff --git a/fs/dax.c b/fs/dax.c
index a86d3cc2b389..5dc33d788d50 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -623,9 +623,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
goto fallback;
if (buffer_unwritten(&bh) || buffer_new(&bh)) {
- int i;
- for (i = 0; i < PTRS_PER_PMD; i++)
- clear_pmem(kaddr + i * PAGE_SIZE, PAGE_SIZE);
+ clear_pmem(kaddr, HPAGE_SIZE);
wmb_pmem();
count_vm_event(PGMAJFAULT);
mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
^ permalink raw reply related [flat|nested] 26+ messages in thread
* [PATCH v2 1/5] pmem, dax: clean up clear_pmem()
@ 2015-10-22 17:10 ` Dan Williams
0 siblings, 0 replies; 26+ messages in thread
From: Dan Williams @ 2015-10-22 17:10 UTC (permalink / raw)
To: axboe
Cc: jack, akpm, linux-nvdimm, Dave Hansen, david, linux-kernel,
willy, ross.zwisler, hch
Both, __dax_pmd_fault, and clear_pmem() were taking special steps to
clear memory a page at a time to take advantage of non-temporal
clear_page() implementations. However, x86_64 does not use
non-temporal instructions for clear_page(), and arch_clear_pmem() was
always incurring the cost of __arch_wb_cache_pmem().
Clean up the assumption that doing clear_pmem() a page at a time is more
performant.
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reported-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
arch/x86/include/asm/pmem.h | 7 +------
fs/dax.c | 4 +---
2 files changed, 2 insertions(+), 9 deletions(-)
diff --git a/arch/x86/include/asm/pmem.h b/arch/x86/include/asm/pmem.h
index d8ce3ec816ab..1544fabcd7f9 100644
--- a/arch/x86/include/asm/pmem.h
+++ b/arch/x86/include/asm/pmem.h
@@ -132,12 +132,7 @@ static inline void arch_clear_pmem(void __pmem *addr, size_t size)
{
void *vaddr = (void __force *)addr;
- /* TODO: implement the zeroing via non-temporal writes */
- if (size == PAGE_SIZE && ((unsigned long)vaddr & ~PAGE_MASK) == 0)
- clear_page(vaddr);
- else
- memset(vaddr, 0, size);
-
+ memset(vaddr, 0, size);
__arch_wb_cache_pmem(vaddr, size);
}
diff --git a/fs/dax.c b/fs/dax.c
index a86d3cc2b389..5dc33d788d50 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -623,9 +623,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
goto fallback;
if (buffer_unwritten(&bh) || buffer_new(&bh)) {
- int i;
- for (i = 0; i < PTRS_PER_PMD; i++)
- clear_pmem(kaddr + i * PAGE_SIZE, PAGE_SIZE);
+ clear_pmem(kaddr, HPAGE_SIZE);
wmb_pmem();
count_vm_event(PGMAJFAULT);
mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
^ permalink raw reply related [flat|nested] 26+ messages in thread
* [PATCH v2 2/5] dax: increase granularity of dax_clear_blocks() operations
2015-10-22 17:10 ` Dan Williams
@ 2015-10-22 17:10 ` Dan Williams
-1 siblings, 0 replies; 26+ messages in thread
From: Dan Williams @ 2015-10-22 17:10 UTC (permalink / raw)
To: axboe
Cc: jack, linux-nvdimm, david, linux-kernel, Jan Kara, willy, akpm,
ross.zwisler, hch
dax_clear_blocks is currently performing a cond_resched() after every
PAGE_SIZE memset. We need not check so frequently, for example md-raid
only calls cond_resched() at stripe granularity. Also, in preparation
for introducing a dax_map_atomic() operation that temporarily pins a dax
mapping move the call to cond_resched() to the outer loop.
Reviewed-by: Jan Kara <jack@suse.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
fs/dax.c | 27 ++++++++++++---------------
1 file changed, 12 insertions(+), 15 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index 5dc33d788d50..f8e543839e5c 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -28,6 +28,7 @@
#include <linux/sched.h>
#include <linux/uio.h>
#include <linux/vmstat.h>
+#include <linux/sizes.h>
int dax_clear_blocks(struct inode *inode, sector_t block, long size)
{
@@ -38,24 +39,20 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
do {
void __pmem *addr;
unsigned long pfn;
- long count;
+ long count, sz;
- count = bdev_direct_access(bdev, sector, &addr, &pfn, size);
+ sz = min_t(long, size, SZ_1M);
+ count = bdev_direct_access(bdev, sector, &addr, &pfn, sz);
if (count < 0)
return count;
- BUG_ON(size < count);
- while (count > 0) {
- unsigned pgsz = PAGE_SIZE - offset_in_page(addr);
- if (pgsz > count)
- pgsz = count;
- clear_pmem(addr, pgsz);
- addr += pgsz;
- size -= pgsz;
- count -= pgsz;
- BUG_ON(pgsz & 511);
- sector += pgsz / 512;
- cond_resched();
- }
+ if (count < sz)
+ sz = count;
+ clear_pmem(addr, sz);
+ addr += sz;
+ size -= sz;
+ BUG_ON(sz & 511);
+ sector += sz / 512;
+ cond_resched();
} while (size);
wmb_pmem();
^ permalink raw reply related [flat|nested] 26+ messages in thread
* [PATCH v2 2/5] dax: increase granularity of dax_clear_blocks() operations
@ 2015-10-22 17:10 ` Dan Williams
0 siblings, 0 replies; 26+ messages in thread
From: Dan Williams @ 2015-10-22 17:10 UTC (permalink / raw)
To: axboe
Cc: jack, linux-nvdimm, david, linux-kernel, Jan Kara, willy, akpm,
ross.zwisler, hch
dax_clear_blocks is currently performing a cond_resched() after every
PAGE_SIZE memset. We need not check so frequently, for example md-raid
only calls cond_resched() at stripe granularity. Also, in preparation
for introducing a dax_map_atomic() operation that temporarily pins a dax
mapping move the call to cond_resched() to the outer loop.
Reviewed-by: Jan Kara <jack@suse.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
fs/dax.c | 27 ++++++++++++---------------
1 file changed, 12 insertions(+), 15 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index 5dc33d788d50..f8e543839e5c 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -28,6 +28,7 @@
#include <linux/sched.h>
#include <linux/uio.h>
#include <linux/vmstat.h>
+#include <linux/sizes.h>
int dax_clear_blocks(struct inode *inode, sector_t block, long size)
{
@@ -38,24 +39,20 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
do {
void __pmem *addr;
unsigned long pfn;
- long count;
+ long count, sz;
- count = bdev_direct_access(bdev, sector, &addr, &pfn, size);
+ sz = min_t(long, size, SZ_1M);
+ count = bdev_direct_access(bdev, sector, &addr, &pfn, sz);
if (count < 0)
return count;
- BUG_ON(size < count);
- while (count > 0) {
- unsigned pgsz = PAGE_SIZE - offset_in_page(addr);
- if (pgsz > count)
- pgsz = count;
- clear_pmem(addr, pgsz);
- addr += pgsz;
- size -= pgsz;
- count -= pgsz;
- BUG_ON(pgsz & 511);
- sector += pgsz / 512;
- cond_resched();
- }
+ if (count < sz)
+ sz = count;
+ clear_pmem(addr, sz);
+ addr += sz;
+ size -= sz;
+ BUG_ON(sz & 511);
+ sector += sz / 512;
+ cond_resched();
} while (size);
wmb_pmem();
^ permalink raw reply related [flat|nested] 26+ messages in thread
* [PATCH v2 3/5] block, dax: fix lifetime of in-kernel dax mappings with dax_map_atomic()
2015-10-22 17:10 ` Dan Williams
@ 2015-10-22 17:10 ` Dan Williams
-1 siblings, 0 replies; 26+ messages in thread
From: Dan Williams @ 2015-10-22 17:10 UTC (permalink / raw)
To: axboe
Cc: Jens Axboe, Boaz Harrosh, jack, akpm, linux-nvdimm, david,
linux-kernel, willy, ross.zwisler, hch
The DAX implementation needs to protect new calls to ->direct_access()
and usage of its return value against unbind of the underlying block
device. Use blk_queue_enter()/blk_queue_exit() to either prevent
blk_cleanup_queue() from proceeding, or fail the dax_map_atomic() if the
request_queue is being torn down.
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Boaz Harrosh <boaz@plexistor.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
block/blk.h | 2 -
fs/dax.c | 165 ++++++++++++++++++++++++++++++++----------------
include/linux/blkdev.h | 2 +
3 files changed, 112 insertions(+), 57 deletions(-)
diff --git a/block/blk.h b/block/blk.h
index 157c93d54dc9..dc7d9411fa45 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -72,8 +72,6 @@ void blk_dequeue_request(struct request *rq);
void __blk_queue_free_tags(struct request_queue *q);
bool __blk_end_bidi_request(struct request *rq, int error,
unsigned int nr_bytes, unsigned int bidi_bytes);
-int blk_queue_enter(struct request_queue *q, gfp_t gfp);
-void blk_queue_exit(struct request_queue *q);
void blk_freeze_queue(struct request_queue *q);
static inline void blk_queue_enter_live(struct request_queue *q)
diff --git a/fs/dax.c b/fs/dax.c
index f8e543839e5c..a480729c00ec 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -30,6 +30,40 @@
#include <linux/vmstat.h>
#include <linux/sizes.h>
+static void __pmem *__dax_map_atomic(struct block_device *bdev, sector_t sector,
+ long size, unsigned long *pfn, long *len)
+{
+ long rc;
+ void __pmem *addr;
+ struct request_queue *q = bdev->bd_queue;
+
+ if (blk_queue_enter(q, GFP_NOWAIT) != 0)
+ return (void __pmem *) ERR_PTR(-EIO);
+ rc = bdev_direct_access(bdev, sector, &addr, pfn, size);
+ if (len)
+ *len = rc;
+ if (rc < 0) {
+ blk_queue_exit(q);
+ return (void __pmem *) ERR_PTR(rc);
+ }
+ return addr;
+}
+
+static void __pmem *dax_map_atomic(struct block_device *bdev, sector_t sector,
+ long size)
+{
+ unsigned long pfn;
+
+ return __dax_map_atomic(bdev, sector, size, &pfn, NULL);
+}
+
+static void dax_unmap_atomic(struct block_device *bdev, void __pmem *addr)
+{
+ if (IS_ERR(addr))
+ return;
+ blk_queue_exit(bdev->bd_queue);
+}
+
int dax_clear_blocks(struct inode *inode, sector_t block, long size)
{
struct block_device *bdev = inode->i_sb->s_bdev;
@@ -42,9 +76,9 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
long count, sz;
sz = min_t(long, size, SZ_1M);
- count = bdev_direct_access(bdev, sector, &addr, &pfn, sz);
- if (count < 0)
- return count;
+ addr = __dax_map_atomic(bdev, sector, size, &pfn, &count);
+ if (IS_ERR(addr))
+ return PTR_ERR(addr);
if (count < sz)
sz = count;
clear_pmem(addr, sz);
@@ -52,6 +86,7 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
size -= sz;
BUG_ON(sz & 511);
sector += sz / 512;
+ dax_unmap_atomic(bdev, addr);
cond_resched();
} while (size);
@@ -60,14 +95,6 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
}
EXPORT_SYMBOL_GPL(dax_clear_blocks);
-static long dax_get_addr(struct buffer_head *bh, void __pmem **addr,
- unsigned blkbits)
-{
- unsigned long pfn;
- sector_t sector = bh->b_blocknr << (blkbits - 9);
- return bdev_direct_access(bh->b_bdev, sector, addr, &pfn, bh->b_size);
-}
-
/* the clear_pmem() calls are ordered by a wmb_pmem() in the caller */
static void dax_new_buf(void __pmem *addr, unsigned size, unsigned first,
loff_t pos, loff_t end)
@@ -97,19 +124,30 @@ static bool buffer_size_valid(struct buffer_head *bh)
return bh->b_state != 0;
}
+
+static sector_t to_sector(const struct buffer_head *bh,
+ const struct inode *inode)
+{
+ sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9);
+
+ return sector;
+}
+
static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
loff_t start, loff_t end, get_block_t get_block,
struct buffer_head *bh)
{
- ssize_t retval = 0;
- loff_t pos = start;
- loff_t max = start;
- loff_t bh_max = start;
- void __pmem *addr;
+ loff_t pos = start, max = start, bh_max = start;
+ struct block_device *bdev = NULL;
+ int rw = iov_iter_rw(iter), rc;
+ long map_len = 0;
+ unsigned long pfn;
+ void __pmem *addr = NULL;
+ void __pmem *kmap = (void __pmem *) ERR_PTR(-EIO);
bool hole = false;
bool need_wmb = false;
- if (iov_iter_rw(iter) != WRITE)
+ if (rw == READ)
end = min(end, i_size_read(inode));
while (pos < end) {
@@ -124,13 +162,13 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
if (pos == bh_max) {
bh->b_size = PAGE_ALIGN(end - pos);
bh->b_state = 0;
- retval = get_block(inode, block, bh,
- iov_iter_rw(iter) == WRITE);
- if (retval)
+ rc = get_block(inode, block, bh, rw == WRITE);
+ if (rc)
break;
if (!buffer_size_valid(bh))
bh->b_size = 1 << blkbits;
bh_max = pos - first + bh->b_size;
+ bdev = bh->b_bdev;
} else {
unsigned done = bh->b_size -
(bh_max - (pos - first));
@@ -138,21 +176,27 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
bh->b_size -= done;
}
- hole = iov_iter_rw(iter) != WRITE && !buffer_written(bh);
+ hole = rw == READ && !buffer_written(bh);
if (hole) {
addr = NULL;
size = bh->b_size - first;
} else {
- retval = dax_get_addr(bh, &addr, blkbits);
- if (retval < 0)
+ dax_unmap_atomic(bdev, kmap);
+ kmap = __dax_map_atomic(bdev,
+ to_sector(bh, inode),
+ bh->b_size, &pfn, &map_len);
+ if (IS_ERR(kmap)) {
+ rc = PTR_ERR(kmap);
break;
+ }
+ addr = kmap;
if (buffer_unwritten(bh) || buffer_new(bh)) {
- dax_new_buf(addr, retval, first, pos,
- end);
+ dax_new_buf(addr, map_len, first, pos,
+ end);
need_wmb = true;
}
addr += first;
- size = retval - first;
+ size = map_len - first;
}
max = min(pos + size, end);
}
@@ -175,8 +219,9 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
if (need_wmb)
wmb_pmem();
+ dax_unmap_atomic(bdev, kmap);
- return (pos == start) ? retval : pos - start;
+ return (pos == start) ? rc : pos - start;
}
/**
@@ -265,28 +310,31 @@ static int dax_load_hole(struct address_space *mapping, struct page *page,
return VM_FAULT_LOCKED;
}
-static int copy_user_bh(struct page *to, struct buffer_head *bh,
- unsigned blkbits, unsigned long vaddr)
+static int copy_user_bh(struct page *to, struct inode *inode,
+ struct buffer_head *bh, unsigned long vaddr)
{
+ struct block_device *bdev = bh->b_bdev;
void __pmem *vfrom;
void *vto;
- if (dax_get_addr(bh, &vfrom, blkbits) < 0)
- return -EIO;
+ vfrom = dax_map_atomic(bdev, to_sector(bh, inode), bh->b_size);
+ if (IS_ERR(vfrom))
+ return PTR_ERR(vfrom);
vto = kmap_atomic(to);
copy_user_page(vto, (void __force *)vfrom, vaddr, to);
kunmap_atomic(vto);
+ dax_unmap_atomic(bdev, vfrom);
return 0;
}
static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
struct vm_area_struct *vma, struct vm_fault *vmf)
{
- struct address_space *mapping = inode->i_mapping;
- sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9);
unsigned long vaddr = (unsigned long)vmf->virtual_address;
- void __pmem *addr;
+ struct address_space *mapping = inode->i_mapping;
+ struct block_device *bdev = bh->b_bdev;
unsigned long pfn;
+ void __pmem *addr;
pgoff_t size;
int error;
@@ -305,11 +353,10 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
goto out;
}
- error = bdev_direct_access(bh->b_bdev, sector, &addr, &pfn, bh->b_size);
- if (error < 0)
- goto out;
- if (error < PAGE_SIZE) {
- error = -EIO;
+ addr = __dax_map_atomic(bdev, to_sector(bh, inode), bh->b_size,
+ &pfn, NULL);
+ if (IS_ERR(addr)) {
+ error = PTR_ERR(addr);
goto out;
}
@@ -317,6 +364,7 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
clear_pmem(addr, PAGE_SIZE);
wmb_pmem();
}
+ dax_unmap_atomic(bdev, addr);
error = vm_insert_mixed(vma, vaddr, pfn);
@@ -412,7 +460,7 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
if (vmf->cow_page) {
struct page *new_page = vmf->cow_page;
if (buffer_written(&bh))
- error = copy_user_bh(new_page, &bh, blkbits, vaddr);
+ error = copy_user_bh(new_page, inode, &bh, vaddr);
else
clear_user_highpage(new_page, vaddr);
if (error)
@@ -524,11 +572,9 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
unsigned blkbits = inode->i_blkbits;
unsigned long pmd_addr = address & PMD_MASK;
bool write = flags & FAULT_FLAG_WRITE;
- long length;
- void __pmem *kaddr;
+ struct block_device *bdev;
pgoff_t size, pgoff;
- sector_t block, sector;
- unsigned long pfn;
+ sector_t block;
int result = 0;
/* Fall back to PTEs if we're going to COW */
@@ -552,9 +598,9 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
block = (sector_t)pgoff << (PAGE_SHIFT - blkbits);
bh.b_size = PMD_SIZE;
- length = get_block(inode, block, &bh, write);
- if (length)
+ if (get_block(inode, block, &bh, write) != 0)
return VM_FAULT_SIGBUS;
+ bdev = bh.b_bdev;
i_mmap_lock_read(mapping);
/*
@@ -609,15 +655,20 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
result = VM_FAULT_NOPAGE;
spin_unlock(ptl);
} else {
- sector = bh.b_blocknr << (blkbits - 9);
- length = bdev_direct_access(bh.b_bdev, sector, &kaddr, &pfn,
- bh.b_size);
- if (length < 0) {
+ long length;
+ unsigned long pfn;
+ void __pmem *kaddr = __dax_map_atomic(bdev,
+ to_sector(&bh, inode), HPAGE_SIZE, &pfn,
+ &length);
+
+ if (IS_ERR(kaddr)) {
result = VM_FAULT_SIGBUS;
goto out;
}
- if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR))
+ if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR)) {
+ dax_unmap_atomic(bdev, kaddr);
goto fallback;
+ }
if (buffer_unwritten(&bh) || buffer_new(&bh)) {
clear_pmem(kaddr, HPAGE_SIZE);
@@ -626,6 +677,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
result |= VM_FAULT_MAJOR;
}
+ dax_unmap_atomic(bdev, kaddr);
result |= vmf_insert_pfn_pmd(vma, address, pmd, pfn, write);
}
@@ -729,12 +781,15 @@ int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length,
if (err < 0)
return err;
if (buffer_written(&bh)) {
- void __pmem *addr;
- err = dax_get_addr(&bh, &addr, inode->i_blkbits);
- if (err < 0)
- return err;
+ struct block_device *bdev = bh.b_bdev;
+ void __pmem *addr = dax_map_atomic(bdev, to_sector(&bh, inode),
+ PAGE_CACHE_SIZE);
+
+ if (IS_ERR(addr))
+ return PTR_ERR(addr);
clear_pmem(addr + offset, length);
wmb_pmem();
+ dax_unmap_atomic(bdev, addr);
}
return 0;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index cf57884db4b7..59a770dad804 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -792,6 +792,8 @@ extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t,
extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t,
struct scsi_ioctl_command __user *);
+extern int blk_queue_enter(struct request_queue *q, gfp_t gfp);
+extern void blk_queue_exit(struct request_queue *q);
extern void blk_start_queue(struct request_queue *q);
extern void blk_stop_queue(struct request_queue *q);
extern void blk_sync_queue(struct request_queue *q);
^ permalink raw reply related [flat|nested] 26+ messages in thread
* [PATCH v2 3/5] block, dax: fix lifetime of in-kernel dax mappings with dax_map_atomic()
@ 2015-10-22 17:10 ` Dan Williams
0 siblings, 0 replies; 26+ messages in thread
From: Dan Williams @ 2015-10-22 17:10 UTC (permalink / raw)
To: axboe
Cc: Jens Axboe, Boaz Harrosh, jack, akpm, linux-nvdimm, david,
linux-kernel, willy, ross.zwisler, hch
The DAX implementation needs to protect new calls to ->direct_access()
and usage of its return value against unbind of the underlying block
device. Use blk_queue_enter()/blk_queue_exit() to either prevent
blk_cleanup_queue() from proceeding, or fail the dax_map_atomic() if the
request_queue is being torn down.
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Boaz Harrosh <boaz@plexistor.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
block/blk.h | 2 -
fs/dax.c | 165 ++++++++++++++++++++++++++++++++----------------
include/linux/blkdev.h | 2 +
3 files changed, 112 insertions(+), 57 deletions(-)
diff --git a/block/blk.h b/block/blk.h
index 157c93d54dc9..dc7d9411fa45 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -72,8 +72,6 @@ void blk_dequeue_request(struct request *rq);
void __blk_queue_free_tags(struct request_queue *q);
bool __blk_end_bidi_request(struct request *rq, int error,
unsigned int nr_bytes, unsigned int bidi_bytes);
-int blk_queue_enter(struct request_queue *q, gfp_t gfp);
-void blk_queue_exit(struct request_queue *q);
void blk_freeze_queue(struct request_queue *q);
static inline void blk_queue_enter_live(struct request_queue *q)
diff --git a/fs/dax.c b/fs/dax.c
index f8e543839e5c..a480729c00ec 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -30,6 +30,40 @@
#include <linux/vmstat.h>
#include <linux/sizes.h>
+static void __pmem *__dax_map_atomic(struct block_device *bdev, sector_t sector,
+ long size, unsigned long *pfn, long *len)
+{
+ long rc;
+ void __pmem *addr;
+ struct request_queue *q = bdev->bd_queue;
+
+ if (blk_queue_enter(q, GFP_NOWAIT) != 0)
+ return (void __pmem *) ERR_PTR(-EIO);
+ rc = bdev_direct_access(bdev, sector, &addr, pfn, size);
+ if (len)
+ *len = rc;
+ if (rc < 0) {
+ blk_queue_exit(q);
+ return (void __pmem *) ERR_PTR(rc);
+ }
+ return addr;
+}
+
+static void __pmem *dax_map_atomic(struct block_device *bdev, sector_t sector,
+ long size)
+{
+ unsigned long pfn;
+
+ return __dax_map_atomic(bdev, sector, size, &pfn, NULL);
+}
+
+static void dax_unmap_atomic(struct block_device *bdev, void __pmem *addr)
+{
+ if (IS_ERR(addr))
+ return;
+ blk_queue_exit(bdev->bd_queue);
+}
+
int dax_clear_blocks(struct inode *inode, sector_t block, long size)
{
struct block_device *bdev = inode->i_sb->s_bdev;
@@ -42,9 +76,9 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
long count, sz;
sz = min_t(long, size, SZ_1M);
- count = bdev_direct_access(bdev, sector, &addr, &pfn, sz);
- if (count < 0)
- return count;
+ addr = __dax_map_atomic(bdev, sector, size, &pfn, &count);
+ if (IS_ERR(addr))
+ return PTR_ERR(addr);
if (count < sz)
sz = count;
clear_pmem(addr, sz);
@@ -52,6 +86,7 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
size -= sz;
BUG_ON(sz & 511);
sector += sz / 512;
+ dax_unmap_atomic(bdev, addr);
cond_resched();
} while (size);
@@ -60,14 +95,6 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
}
EXPORT_SYMBOL_GPL(dax_clear_blocks);
-static long dax_get_addr(struct buffer_head *bh, void __pmem **addr,
- unsigned blkbits)
-{
- unsigned long pfn;
- sector_t sector = bh->b_blocknr << (blkbits - 9);
- return bdev_direct_access(bh->b_bdev, sector, addr, &pfn, bh->b_size);
-}
-
/* the clear_pmem() calls are ordered by a wmb_pmem() in the caller */
static void dax_new_buf(void __pmem *addr, unsigned size, unsigned first,
loff_t pos, loff_t end)
@@ -97,19 +124,30 @@ static bool buffer_size_valid(struct buffer_head *bh)
return bh->b_state != 0;
}
+
+static sector_t to_sector(const struct buffer_head *bh,
+ const struct inode *inode)
+{
+ sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9);
+
+ return sector;
+}
+
static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
loff_t start, loff_t end, get_block_t get_block,
struct buffer_head *bh)
{
- ssize_t retval = 0;
- loff_t pos = start;
- loff_t max = start;
- loff_t bh_max = start;
- void __pmem *addr;
+ loff_t pos = start, max = start, bh_max = start;
+ struct block_device *bdev = NULL;
+ int rw = iov_iter_rw(iter), rc;
+ long map_len = 0;
+ unsigned long pfn;
+ void __pmem *addr = NULL;
+ void __pmem *kmap = (void __pmem *) ERR_PTR(-EIO);
bool hole = false;
bool need_wmb = false;
- if (iov_iter_rw(iter) != WRITE)
+ if (rw == READ)
end = min(end, i_size_read(inode));
while (pos < end) {
@@ -124,13 +162,13 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
if (pos == bh_max) {
bh->b_size = PAGE_ALIGN(end - pos);
bh->b_state = 0;
- retval = get_block(inode, block, bh,
- iov_iter_rw(iter) == WRITE);
- if (retval)
+ rc = get_block(inode, block, bh, rw == WRITE);
+ if (rc)
break;
if (!buffer_size_valid(bh))
bh->b_size = 1 << blkbits;
bh_max = pos - first + bh->b_size;
+ bdev = bh->b_bdev;
} else {
unsigned done = bh->b_size -
(bh_max - (pos - first));
@@ -138,21 +176,27 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
bh->b_size -= done;
}
- hole = iov_iter_rw(iter) != WRITE && !buffer_written(bh);
+ hole = rw == READ && !buffer_written(bh);
if (hole) {
addr = NULL;
size = bh->b_size - first;
} else {
- retval = dax_get_addr(bh, &addr, blkbits);
- if (retval < 0)
+ dax_unmap_atomic(bdev, kmap);
+ kmap = __dax_map_atomic(bdev,
+ to_sector(bh, inode),
+ bh->b_size, &pfn, &map_len);
+ if (IS_ERR(kmap)) {
+ rc = PTR_ERR(kmap);
break;
+ }
+ addr = kmap;
if (buffer_unwritten(bh) || buffer_new(bh)) {
- dax_new_buf(addr, retval, first, pos,
- end);
+ dax_new_buf(addr, map_len, first, pos,
+ end);
need_wmb = true;
}
addr += first;
- size = retval - first;
+ size = map_len - first;
}
max = min(pos + size, end);
}
@@ -175,8 +219,9 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
if (need_wmb)
wmb_pmem();
+ dax_unmap_atomic(bdev, kmap);
- return (pos == start) ? retval : pos - start;
+ return (pos == start) ? rc : pos - start;
}
/**
@@ -265,28 +310,31 @@ static int dax_load_hole(struct address_space *mapping, struct page *page,
return VM_FAULT_LOCKED;
}
-static int copy_user_bh(struct page *to, struct buffer_head *bh,
- unsigned blkbits, unsigned long vaddr)
+static int copy_user_bh(struct page *to, struct inode *inode,
+ struct buffer_head *bh, unsigned long vaddr)
{
+ struct block_device *bdev = bh->b_bdev;
void __pmem *vfrom;
void *vto;
- if (dax_get_addr(bh, &vfrom, blkbits) < 0)
- return -EIO;
+ vfrom = dax_map_atomic(bdev, to_sector(bh, inode), bh->b_size);
+ if (IS_ERR(vfrom))
+ return PTR_ERR(vfrom);
vto = kmap_atomic(to);
copy_user_page(vto, (void __force *)vfrom, vaddr, to);
kunmap_atomic(vto);
+ dax_unmap_atomic(bdev, vfrom);
return 0;
}
static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
struct vm_area_struct *vma, struct vm_fault *vmf)
{
- struct address_space *mapping = inode->i_mapping;
- sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9);
unsigned long vaddr = (unsigned long)vmf->virtual_address;
- void __pmem *addr;
+ struct address_space *mapping = inode->i_mapping;
+ struct block_device *bdev = bh->b_bdev;
unsigned long pfn;
+ void __pmem *addr;
pgoff_t size;
int error;
@@ -305,11 +353,10 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
goto out;
}
- error = bdev_direct_access(bh->b_bdev, sector, &addr, &pfn, bh->b_size);
- if (error < 0)
- goto out;
- if (error < PAGE_SIZE) {
- error = -EIO;
+ addr = __dax_map_atomic(bdev, to_sector(bh, inode), bh->b_size,
+ &pfn, NULL);
+ if (IS_ERR(addr)) {
+ error = PTR_ERR(addr);
goto out;
}
@@ -317,6 +364,7 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
clear_pmem(addr, PAGE_SIZE);
wmb_pmem();
}
+ dax_unmap_atomic(bdev, addr);
error = vm_insert_mixed(vma, vaddr, pfn);
@@ -412,7 +460,7 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
if (vmf->cow_page) {
struct page *new_page = vmf->cow_page;
if (buffer_written(&bh))
- error = copy_user_bh(new_page, &bh, blkbits, vaddr);
+ error = copy_user_bh(new_page, inode, &bh, vaddr);
else
clear_user_highpage(new_page, vaddr);
if (error)
@@ -524,11 +572,9 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
unsigned blkbits = inode->i_blkbits;
unsigned long pmd_addr = address & PMD_MASK;
bool write = flags & FAULT_FLAG_WRITE;
- long length;
- void __pmem *kaddr;
+ struct block_device *bdev;
pgoff_t size, pgoff;
- sector_t block, sector;
- unsigned long pfn;
+ sector_t block;
int result = 0;
/* Fall back to PTEs if we're going to COW */
@@ -552,9 +598,9 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
block = (sector_t)pgoff << (PAGE_SHIFT - blkbits);
bh.b_size = PMD_SIZE;
- length = get_block(inode, block, &bh, write);
- if (length)
+ if (get_block(inode, block, &bh, write) != 0)
return VM_FAULT_SIGBUS;
+ bdev = bh.b_bdev;
i_mmap_lock_read(mapping);
/*
@@ -609,15 +655,20 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
result = VM_FAULT_NOPAGE;
spin_unlock(ptl);
} else {
- sector = bh.b_blocknr << (blkbits - 9);
- length = bdev_direct_access(bh.b_bdev, sector, &kaddr, &pfn,
- bh.b_size);
- if (length < 0) {
+ long length;
+ unsigned long pfn;
+ void __pmem *kaddr = __dax_map_atomic(bdev,
+ to_sector(&bh, inode), HPAGE_SIZE, &pfn,
+ &length);
+
+ if (IS_ERR(kaddr)) {
result = VM_FAULT_SIGBUS;
goto out;
}
- if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR))
+ if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR)) {
+ dax_unmap_atomic(bdev, kaddr);
goto fallback;
+ }
if (buffer_unwritten(&bh) || buffer_new(&bh)) {
clear_pmem(kaddr, HPAGE_SIZE);
@@ -626,6 +677,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
result |= VM_FAULT_MAJOR;
}
+ dax_unmap_atomic(bdev, kaddr);
result |= vmf_insert_pfn_pmd(vma, address, pmd, pfn, write);
}
@@ -729,12 +781,15 @@ int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length,
if (err < 0)
return err;
if (buffer_written(&bh)) {
- void __pmem *addr;
- err = dax_get_addr(&bh, &addr, inode->i_blkbits);
- if (err < 0)
- return err;
+ struct block_device *bdev = bh.b_bdev;
+ void __pmem *addr = dax_map_atomic(bdev, to_sector(&bh, inode),
+ PAGE_CACHE_SIZE);
+
+ if (IS_ERR(addr))
+ return PTR_ERR(addr);
clear_pmem(addr + offset, length);
wmb_pmem();
+ dax_unmap_atomic(bdev, addr);
}
return 0;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index cf57884db4b7..59a770dad804 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -792,6 +792,8 @@ extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t,
extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t,
struct scsi_ioctl_command __user *);
+extern int blk_queue_enter(struct request_queue *q, gfp_t gfp);
+extern void blk_queue_exit(struct request_queue *q);
extern void blk_start_queue(struct request_queue *q);
extern void blk_stop_queue(struct request_queue *q);
extern void blk_sync_queue(struct request_queue *q);
^ permalink raw reply related [flat|nested] 26+ messages in thread
* [PATCH v2 4/5] block: introduce bdev_file_inode()
2015-10-22 17:10 ` Dan Williams
@ 2015-10-22 17:10 ` Dan Williams
-1 siblings, 0 replies; 26+ messages in thread
From: Dan Williams @ 2015-10-22 17:10 UTC (permalink / raw)
To: axboe
Cc: jack, linux-nvdimm, david, linux-kernel, Al Viro, ross.zwisler,
willy, akpm, hch
Similar to the file_inode() helper, provide a helper to lookup the inode for a
raw block device itself.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
fs/block_dev.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 0a793c7930eb..c1f691859a56 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -147,11 +147,16 @@ blkdev_get_block(struct inode *inode, sector_t iblock,
return 0;
}
+static struct inode *bdev_file_inode(struct file *file)
+{
+ return file->f_mapping->host;
+}
+
static ssize_t
blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
{
struct file *file = iocb->ki_filp;
- struct inode *inode = file->f_mapping->host;
+ struct inode *inode = bdev_file_inode(file);
if (IS_DAX(inode))
return dax_do_io(iocb, inode, iter, offset, blkdev_get_block,
@@ -329,7 +334,7 @@ static int blkdev_write_end(struct file *file, struct address_space *mapping,
*/
static loff_t block_llseek(struct file *file, loff_t offset, int whence)
{
- struct inode *bd_inode = file->f_mapping->host;
+ struct inode *bd_inode = bdev_file_inode(file);
loff_t retval;
mutex_lock(&bd_inode->i_mutex);
@@ -340,7 +345,7 @@ static loff_t block_llseek(struct file *file, loff_t offset, int whence)
int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
{
- struct inode *bd_inode = filp->f_mapping->host;
+ struct inode *bd_inode = bdev_file_inode(filp);
struct block_device *bdev = I_BDEV(bd_inode);
int error;
@@ -1579,14 +1584,14 @@ EXPORT_SYMBOL(blkdev_put);
static int blkdev_close(struct inode * inode, struct file * filp)
{
- struct block_device *bdev = I_BDEV(filp->f_mapping->host);
+ struct block_device *bdev = I_BDEV(bdev_file_inode(filp));
blkdev_put(bdev, filp->f_mode);
return 0;
}
static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
{
- struct block_device *bdev = I_BDEV(file->f_mapping->host);
+ struct block_device *bdev = I_BDEV(bdev_file_inode(file));
fmode_t mode = file->f_mode;
/*
@@ -1611,7 +1616,7 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
- struct inode *bd_inode = file->f_mapping->host;
+ struct inode *bd_inode = bdev_file_inode(file);
loff_t size = i_size_read(bd_inode);
struct blk_plug plug;
ssize_t ret;
@@ -1643,7 +1648,7 @@ EXPORT_SYMBOL_GPL(blkdev_write_iter);
ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct file *file = iocb->ki_filp;
- struct inode *bd_inode = file->f_mapping->host;
+ struct inode *bd_inode = bdev_file_inode(file);
loff_t size = i_size_read(bd_inode);
loff_t pos = iocb->ki_pos;
^ permalink raw reply related [flat|nested] 26+ messages in thread
* [PATCH v2 4/5] block: introduce bdev_file_inode()
@ 2015-10-22 17:10 ` Dan Williams
0 siblings, 0 replies; 26+ messages in thread
From: Dan Williams @ 2015-10-22 17:10 UTC (permalink / raw)
To: axboe
Cc: jack, linux-nvdimm, david, linux-kernel, Al Viro, ross.zwisler,
willy, akpm, hch
Similar to the file_inode() helper, provide a helper to lookup the inode for a
raw block device itself.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
fs/block_dev.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 0a793c7930eb..c1f691859a56 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -147,11 +147,16 @@ blkdev_get_block(struct inode *inode, sector_t iblock,
return 0;
}
+static struct inode *bdev_file_inode(struct file *file)
+{
+ return file->f_mapping->host;
+}
+
static ssize_t
blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
{
struct file *file = iocb->ki_filp;
- struct inode *inode = file->f_mapping->host;
+ struct inode *inode = bdev_file_inode(file);
if (IS_DAX(inode))
return dax_do_io(iocb, inode, iter, offset, blkdev_get_block,
@@ -329,7 +334,7 @@ static int blkdev_write_end(struct file *file, struct address_space *mapping,
*/
static loff_t block_llseek(struct file *file, loff_t offset, int whence)
{
- struct inode *bd_inode = file->f_mapping->host;
+ struct inode *bd_inode = bdev_file_inode(file);
loff_t retval;
mutex_lock(&bd_inode->i_mutex);
@@ -340,7 +345,7 @@ static loff_t block_llseek(struct file *file, loff_t offset, int whence)
int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
{
- struct inode *bd_inode = filp->f_mapping->host;
+ struct inode *bd_inode = bdev_file_inode(filp);
struct block_device *bdev = I_BDEV(bd_inode);
int error;
@@ -1579,14 +1584,14 @@ EXPORT_SYMBOL(blkdev_put);
static int blkdev_close(struct inode * inode, struct file * filp)
{
- struct block_device *bdev = I_BDEV(filp->f_mapping->host);
+ struct block_device *bdev = I_BDEV(bdev_file_inode(filp));
blkdev_put(bdev, filp->f_mode);
return 0;
}
static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
{
- struct block_device *bdev = I_BDEV(file->f_mapping->host);
+ struct block_device *bdev = I_BDEV(bdev_file_inode(file));
fmode_t mode = file->f_mode;
/*
@@ -1611,7 +1616,7 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
- struct inode *bd_inode = file->f_mapping->host;
+ struct inode *bd_inode = bdev_file_inode(file);
loff_t size = i_size_read(bd_inode);
struct blk_plug plug;
ssize_t ret;
@@ -1643,7 +1648,7 @@ EXPORT_SYMBOL_GPL(blkdev_write_iter);
ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct file *file = iocb->ki_filp;
- struct inode *bd_inode = file->f_mapping->host;
+ struct inode *bd_inode = bdev_file_inode(file);
loff_t size = i_size_read(bd_inode);
loff_t pos = iocb->ki_pos;
^ permalink raw reply related [flat|nested] 26+ messages in thread
* [PATCH v2 5/5] block: enable dax for raw block devices
2015-10-22 17:10 ` Dan Williams
@ 2015-10-22 17:10 ` Dan Williams
-1 siblings, 0 replies; 26+ messages in thread
From: Dan Williams @ 2015-10-22 17:10 UTC (permalink / raw)
To: axboe
Cc: jack, linux-nvdimm, Jan Kara, david, linux-kernel, Jeff Moyer,
ross.zwisler, willy, akpm, hch
If an application wants exclusive access to all of the persistent memory
provided by an NVDIMM namespace it can use this raw-block-dax facility
to forgo establishing a filesystem. This capability is targeted
primarily to hypervisors wanting to provision persistent memory for
guests.
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
fs/block_dev.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 59 insertions(+), 1 deletion(-)
diff --git a/fs/block_dev.c b/fs/block_dev.c
index c1f691859a56..210d05103657 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1687,13 +1687,71 @@ static const struct address_space_operations def_blk_aops = {
.is_dirty_writeback = buffer_check_dirty_writeback,
};
+#ifdef CONFIG_FS_DAX
+/*
+ * In the raw block case we do not need to contend with truncation nor
+ * unwritten file extents. Without those concerns there is no need for
+ * additional locking beyond the mmap_sem context that these routines
+ * are already executing under.
+ *
+ * Note, there is no protection if the block device is dynamically
+ * resized (partition grow/shrink) during a fault. A stable block device
+ * size is already not enforced in the blkdev_direct_IO path.
+ *
+ * For DAX, it is the responsibility of the block device driver to
+ * ensure the whole-disk device size is stable while requests are in
+ * flight.
+ *
+ * Finally, in contrast to the generic_file_mmap() path, there are no
+ * calls to sb_start_pagefault(). That is meant to synchronize write
+ * faults against requests to freeze the contents of the filesystem
+ * hosting vma->vm_file. However, in the case of a block device special
+ * file, it is a 0-sized device node usually hosted on devtmpfs, i.e.
+ * nothing to do with the super_block for bdev_file_inode(vma->vm_file).
+ * We could call get_super() in this path to retrieve the right
+ * super_block, but the generic_file_mmap() path does not do this for
+ * the CONFIG_FS_DAX=n case.
+ */
+static int blkdev_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ return __dax_fault(vma, vmf, blkdev_get_block, NULL);
+}
+
+static int blkdev_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
+ pmd_t *pmd, unsigned int flags)
+{
+ return __dax_pmd_fault(vma, addr, pmd, flags, blkdev_get_block, NULL);
+}
+
+static const struct vm_operations_struct blkdev_dax_vm_ops = {
+ .page_mkwrite = blkdev_dax_fault,
+ .fault = blkdev_dax_fault,
+ .pmd_fault = blkdev_dax_pmd_fault,
+};
+
+static int blkdev_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ struct inode *bd_inode = bdev_file_inode(file);
+
+ if (!IS_DAX(bd_inode))
+ return generic_file_mmap(file, vma);
+
+ file_accessed(file);
+ vma->vm_ops = &blkdev_dax_vm_ops;
+ vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
+ return 0;
+}
+#else
+#define blkdev_mmap generic_file_mmap
+#endif
+
const struct file_operations def_blk_fops = {
.open = blkdev_open,
.release = blkdev_close,
.llseek = block_llseek,
.read_iter = blkdev_read_iter,
.write_iter = blkdev_write_iter,
- .mmap = generic_file_mmap,
+ .mmap = blkdev_mmap,
.fsync = blkdev_fsync,
.unlocked_ioctl = block_ioctl,
#ifdef CONFIG_COMPAT
^ permalink raw reply related [flat|nested] 26+ messages in thread
* [PATCH v2 5/5] block: enable dax for raw block devices
@ 2015-10-22 17:10 ` Dan Williams
0 siblings, 0 replies; 26+ messages in thread
From: Dan Williams @ 2015-10-22 17:10 UTC (permalink / raw)
To: axboe
Cc: jack, linux-nvdimm, Jan Kara, david, linux-kernel, Jeff Moyer,
ross.zwisler, willy, akpm, hch
If an application wants exclusive access to all of the persistent memory
provided by an NVDIMM namespace it can use this raw-block-dax facility
to forgo establishing a filesystem. This capability is targeted
primarily to hypervisors wanting to provision persistent memory for
guests.
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
fs/block_dev.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 59 insertions(+), 1 deletion(-)
diff --git a/fs/block_dev.c b/fs/block_dev.c
index c1f691859a56..210d05103657 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1687,13 +1687,71 @@ static const struct address_space_operations def_blk_aops = {
.is_dirty_writeback = buffer_check_dirty_writeback,
};
+#ifdef CONFIG_FS_DAX
+/*
+ * In the raw block case we do not need to contend with truncation nor
+ * unwritten file extents. Without those concerns there is no need for
+ * additional locking beyond the mmap_sem context that these routines
+ * are already executing under.
+ *
+ * Note, there is no protection if the block device is dynamically
+ * resized (partition grow/shrink) during a fault. A stable block device
+ * size is already not enforced in the blkdev_direct_IO path.
+ *
+ * For DAX, it is the responsibility of the block device driver to
+ * ensure the whole-disk device size is stable while requests are in
+ * flight.
+ *
+ * Finally, in contrast to the generic_file_mmap() path, there are no
+ * calls to sb_start_pagefault(). That is meant to synchronize write
+ * faults against requests to freeze the contents of the filesystem
+ * hosting vma->vm_file. However, in the case of a block device special
+ * file, it is a 0-sized device node usually hosted on devtmpfs, i.e.
+ * nothing to do with the super_block for bdev_file_inode(vma->vm_file).
+ * We could call get_super() in this path to retrieve the right
+ * super_block, but the generic_file_mmap() path does not do this for
+ * the CONFIG_FS_DAX=n case.
+ */
+static int blkdev_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ return __dax_fault(vma, vmf, blkdev_get_block, NULL);
+}
+
+static int blkdev_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
+ pmd_t *pmd, unsigned int flags)
+{
+ return __dax_pmd_fault(vma, addr, pmd, flags, blkdev_get_block, NULL);
+}
+
+static const struct vm_operations_struct blkdev_dax_vm_ops = {
+ .page_mkwrite = blkdev_dax_fault,
+ .fault = blkdev_dax_fault,
+ .pmd_fault = blkdev_dax_pmd_fault,
+};
+
+static int blkdev_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ struct inode *bd_inode = bdev_file_inode(file);
+
+ if (!IS_DAX(bd_inode))
+ return generic_file_mmap(file, vma);
+
+ file_accessed(file);
+ vma->vm_ops = &blkdev_dax_vm_ops;
+ vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
+ return 0;
+}
+#else
+#define blkdev_mmap generic_file_mmap
+#endif
+
const struct file_operations def_blk_fops = {
.open = blkdev_open,
.release = blkdev_close,
.llseek = block_llseek,
.read_iter = blkdev_read_iter,
.write_iter = blkdev_write_iter,
- .mmap = generic_file_mmap,
+ .mmap = blkdev_mmap,
.fsync = blkdev_fsync,
.unlocked_ioctl = block_ioctl,
#ifdef CONFIG_COMPAT
^ permalink raw reply related [flat|nested] 26+ messages in thread
* Re: [PATCH v2 4/5] block: introduce bdev_file_inode()
2015-10-22 17:10 ` Dan Williams
@ 2015-10-22 20:37 ` Jan Kara
-1 siblings, 0 replies; 26+ messages in thread
From: Jan Kara @ 2015-10-22 20:37 UTC (permalink / raw)
To: Dan Williams
Cc: axboe, jack, linux-nvdimm, david, linux-kernel, Al Viro,
ross.zwisler, willy, akpm, hch
On Thu 22-10-15 13:10:38, Dan Williams wrote:
> Similar to the file_inode() helper, provide a helper to lookup the inode for a
> raw block device itself.
>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Suggested-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Looks good. You can add:
Reviewed-by: Jan Kara <jack@suse.com>
Honza
> ---
> fs/block_dev.c | 19 ++++++++++++-------
> 1 file changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index 0a793c7930eb..c1f691859a56 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -147,11 +147,16 @@ blkdev_get_block(struct inode *inode, sector_t iblock,
> return 0;
> }
>
> +static struct inode *bdev_file_inode(struct file *file)
> +{
> + return file->f_mapping->host;
> +}
> +
> static ssize_t
> blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
> {
> struct file *file = iocb->ki_filp;
> - struct inode *inode = file->f_mapping->host;
> + struct inode *inode = bdev_file_inode(file);
>
> if (IS_DAX(inode))
> return dax_do_io(iocb, inode, iter, offset, blkdev_get_block,
> @@ -329,7 +334,7 @@ static int blkdev_write_end(struct file *file, struct address_space *mapping,
> */
> static loff_t block_llseek(struct file *file, loff_t offset, int whence)
> {
> - struct inode *bd_inode = file->f_mapping->host;
> + struct inode *bd_inode = bdev_file_inode(file);
> loff_t retval;
>
> mutex_lock(&bd_inode->i_mutex);
> @@ -340,7 +345,7 @@ static loff_t block_llseek(struct file *file, loff_t offset, int whence)
>
> int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
> {
> - struct inode *bd_inode = filp->f_mapping->host;
> + struct inode *bd_inode = bdev_file_inode(filp);
> struct block_device *bdev = I_BDEV(bd_inode);
> int error;
>
> @@ -1579,14 +1584,14 @@ EXPORT_SYMBOL(blkdev_put);
>
> static int blkdev_close(struct inode * inode, struct file * filp)
> {
> - struct block_device *bdev = I_BDEV(filp->f_mapping->host);
> + struct block_device *bdev = I_BDEV(bdev_file_inode(filp));
> blkdev_put(bdev, filp->f_mode);
> return 0;
> }
>
> static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
> {
> - struct block_device *bdev = I_BDEV(file->f_mapping->host);
> + struct block_device *bdev = I_BDEV(bdev_file_inode(file));
> fmode_t mode = file->f_mode;
>
> /*
> @@ -1611,7 +1616,7 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
> ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
> {
> struct file *file = iocb->ki_filp;
> - struct inode *bd_inode = file->f_mapping->host;
> + struct inode *bd_inode = bdev_file_inode(file);
> loff_t size = i_size_read(bd_inode);
> struct blk_plug plug;
> ssize_t ret;
> @@ -1643,7 +1648,7 @@ EXPORT_SYMBOL_GPL(blkdev_write_iter);
> ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
> {
> struct file *file = iocb->ki_filp;
> - struct inode *bd_inode = file->f_mapping->host;
> + struct inode *bd_inode = bdev_file_inode(file);
> loff_t size = i_size_read(bd_inode);
> loff_t pos = iocb->ki_pos;
>
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 26+ messages in thread
* Re: [PATCH v2 4/5] block: introduce bdev_file_inode()
@ 2015-10-22 20:37 ` Jan Kara
0 siblings, 0 replies; 26+ messages in thread
From: Jan Kara @ 2015-10-22 20:37 UTC (permalink / raw)
To: Dan Williams
Cc: axboe, jack, linux-nvdimm, david, linux-kernel, Al Viro,
ross.zwisler, willy, akpm, hch
On Thu 22-10-15 13:10:38, Dan Williams wrote:
> Similar to the file_inode() helper, provide a helper to lookup the inode for a
> raw block device itself.
>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Suggested-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Looks good. You can add:
Reviewed-by: Jan Kara <jack@suse.com>
Honza
> ---
> fs/block_dev.c | 19 ++++++++++++-------
> 1 file changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index 0a793c7930eb..c1f691859a56 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -147,11 +147,16 @@ blkdev_get_block(struct inode *inode, sector_t iblock,
> return 0;
> }
>
> +static struct inode *bdev_file_inode(struct file *file)
> +{
> + return file->f_mapping->host;
> +}
> +
> static ssize_t
> blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
> {
> struct file *file = iocb->ki_filp;
> - struct inode *inode = file->f_mapping->host;
> + struct inode *inode = bdev_file_inode(file);
>
> if (IS_DAX(inode))
> return dax_do_io(iocb, inode, iter, offset, blkdev_get_block,
> @@ -329,7 +334,7 @@ static int blkdev_write_end(struct file *file, struct address_space *mapping,
> */
> static loff_t block_llseek(struct file *file, loff_t offset, int whence)
> {
> - struct inode *bd_inode = file->f_mapping->host;
> + struct inode *bd_inode = bdev_file_inode(file);
> loff_t retval;
>
> mutex_lock(&bd_inode->i_mutex);
> @@ -340,7 +345,7 @@ static loff_t block_llseek(struct file *file, loff_t offset, int whence)
>
> int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
> {
> - struct inode *bd_inode = filp->f_mapping->host;
> + struct inode *bd_inode = bdev_file_inode(filp);
> struct block_device *bdev = I_BDEV(bd_inode);
> int error;
>
> @@ -1579,14 +1584,14 @@ EXPORT_SYMBOL(blkdev_put);
>
> static int blkdev_close(struct inode * inode, struct file * filp)
> {
> - struct block_device *bdev = I_BDEV(filp->f_mapping->host);
> + struct block_device *bdev = I_BDEV(bdev_file_inode(filp));
> blkdev_put(bdev, filp->f_mode);
> return 0;
> }
>
> static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
> {
> - struct block_device *bdev = I_BDEV(file->f_mapping->host);
> + struct block_device *bdev = I_BDEV(bdev_file_inode(file));
> fmode_t mode = file->f_mode;
>
> /*
> @@ -1611,7 +1616,7 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
> ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
> {
> struct file *file = iocb->ki_filp;
> - struct inode *bd_inode = file->f_mapping->host;
> + struct inode *bd_inode = bdev_file_inode(file);
> loff_t size = i_size_read(bd_inode);
> struct blk_plug plug;
> ssize_t ret;
> @@ -1643,7 +1648,7 @@ EXPORT_SYMBOL_GPL(blkdev_write_iter);
> ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
> {
> struct file *file = iocb->ki_filp;
> - struct inode *bd_inode = file->f_mapping->host;
> + struct inode *bd_inode = bdev_file_inode(file);
> loff_t size = i_size_read(bd_inode);
> loff_t pos = iocb->ki_pos;
>
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 26+ messages in thread
* Re: [PATCH v2 1/5] pmem, dax: clean up clear_pmem()
2015-10-22 17:10 ` Dan Williams
(?)
@ 2015-10-22 20:48 ` Jeff Moyer
2015-10-22 22:29 ` Dan Williams
-1 siblings, 1 reply; 26+ messages in thread
From: Jeff Moyer @ 2015-10-22 20:48 UTC (permalink / raw)
To: Dan Williams
Cc: axboe, jack, linux-nvdimm, Dave Hansen, david, linux-kernel, hch, akpm
Dan Williams <dan.j.williams@intel.com> writes:
> Both, __dax_pmd_fault, and clear_pmem() were taking special steps to
> clear memory a page at a time to take advantage of non-temporal
> clear_page() implementations. However, x86_64 does not use
> non-temporal instructions for clear_page(), and arch_clear_pmem() was
> always incurring the cost of __arch_wb_cache_pmem().
>
> Clean up the assumption that doing clear_pmem() a page at a time is more
> performant.
Wouldn't another solution be to actually use non-temporal stores? Why
did you choose to punt?
Cheers,
Jeff
>
> Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
> Reported-by: Dave Hansen <dave.hansen@linux.intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> arch/x86/include/asm/pmem.h | 7 +------
> fs/dax.c | 4 +---
> 2 files changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/include/asm/pmem.h b/arch/x86/include/asm/pmem.h
> index d8ce3ec816ab..1544fabcd7f9 100644
> --- a/arch/x86/include/asm/pmem.h
> +++ b/arch/x86/include/asm/pmem.h
> @@ -132,12 +132,7 @@ static inline void arch_clear_pmem(void __pmem *addr, size_t size)
> {
> void *vaddr = (void __force *)addr;
>
> - /* TODO: implement the zeroing via non-temporal writes */
> - if (size == PAGE_SIZE && ((unsigned long)vaddr & ~PAGE_MASK) == 0)
> - clear_page(vaddr);
> - else
> - memset(vaddr, 0, size);
> -
> + memset(vaddr, 0, size);
> __arch_wb_cache_pmem(vaddr, size);
> }
>
> diff --git a/fs/dax.c b/fs/dax.c
> index a86d3cc2b389..5dc33d788d50 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -623,9 +623,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
> goto fallback;
>
> if (buffer_unwritten(&bh) || buffer_new(&bh)) {
> - int i;
> - for (i = 0; i < PTRS_PER_PMD; i++)
> - clear_pmem(kaddr + i * PAGE_SIZE, PAGE_SIZE);
> + clear_pmem(kaddr, HPAGE_SIZE);
> wmb_pmem();
> count_vm_event(PGMAJFAULT);
> mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
>
> _______________________________________________
> Linux-nvdimm mailing list
> Linux-nvdimm@lists.01.org
> https://lists.01.org/mailman/listinfo/linux-nvdimm
^ permalink raw reply [flat|nested] 26+ messages in thread
* Re: [PATCH v2 2/5] dax: increase granularity of dax_clear_blocks() operations
2015-10-22 17:10 ` Dan Williams
(?)
@ 2015-10-22 21:04 ` Jeff Moyer
2015-10-22 22:57 ` Williams, Dan J
-1 siblings, 1 reply; 26+ messages in thread
From: Jeff Moyer @ 2015-10-22 21:04 UTC (permalink / raw)
To: Dan Williams
Cc: axboe, jack, linux-nvdimm, david, linux-kernel, hch, Jan Kara, akpm
Dan Williams <dan.j.williams@intel.com> writes:
> dax_clear_blocks is currently performing a cond_resched() after every
> PAGE_SIZE memset. We need not check so frequently, for example md-raid
> only calls cond_resched() at stripe granularity. Also, in preparation
> for introducing a dax_map_atomic() operation that temporarily pins a dax
> mapping move the call to cond_resched() to the outer loop.
There's nothing wrong with the mechanics here, but why bother? I only
see 1 caller in the kernel, and that caller passes in
1<<inode->i_blkbits for the size (so 1 page or less). Did you plan to
add other callers? I don't see them in this particular patch set.
Again, I'm not taking issue with the patch, I'm just wondering what
motivated the change.
Thanks!
Jeff
>
> Reviewed-by: Jan Kara <jack@suse.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> fs/dax.c | 27 ++++++++++++---------------
> 1 file changed, 12 insertions(+), 15 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 5dc33d788d50..f8e543839e5c 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -28,6 +28,7 @@
> #include <linux/sched.h>
> #include <linux/uio.h>
> #include <linux/vmstat.h>
> +#include <linux/sizes.h>
>
> int dax_clear_blocks(struct inode *inode, sector_t block, long size)
> {
> @@ -38,24 +39,20 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
> do {
> void __pmem *addr;
> unsigned long pfn;
> - long count;
> + long count, sz;
>
> - count = bdev_direct_access(bdev, sector, &addr, &pfn, size);
> + sz = min_t(long, size, SZ_1M);
> + count = bdev_direct_access(bdev, sector, &addr, &pfn, sz);
> if (count < 0)
> return count;
> - BUG_ON(size < count);
> - while (count > 0) {
> - unsigned pgsz = PAGE_SIZE - offset_in_page(addr);
> - if (pgsz > count)
> - pgsz = count;
> - clear_pmem(addr, pgsz);
> - addr += pgsz;
> - size -= pgsz;
> - count -= pgsz;
> - BUG_ON(pgsz & 511);
> - sector += pgsz / 512;
> - cond_resched();
> - }
> + if (count < sz)
> + sz = count;
> + clear_pmem(addr, sz);
> + addr += sz;
> + size -= sz;
> + BUG_ON(sz & 511);
> + sector += sz / 512;
> + cond_resched();
> } while (size);
>
> wmb_pmem();
>
> _______________________________________________
> Linux-nvdimm mailing list
> Linux-nvdimm@lists.01.org
> https://lists.01.org/mailman/listinfo/linux-nvdimm
^ permalink raw reply [flat|nested] 26+ messages in thread
* Re: [PATCH v2 1/5] pmem, dax: clean up clear_pmem()
2015-10-22 20:48 ` Jeff Moyer
@ 2015-10-22 22:29 ` Dan Williams
2015-10-28 21:01 ` Jeff Moyer
0 siblings, 1 reply; 26+ messages in thread
From: Dan Williams @ 2015-10-22 22:29 UTC (permalink / raw)
To: Jeff Moyer
Cc: Jens Axboe, Jan Kara, linux-nvdimm, Dave Hansen, david,
linux-kernel, Christoph Hellwig, Andrew Morton
On Thu, Oct 22, 2015 at 1:48 PM, Jeff Moyer <jmoyer@redhat.com> wrote:
> Dan Williams <dan.j.williams@intel.com> writes:
>
>> Both, __dax_pmd_fault, and clear_pmem() were taking special steps to
>> clear memory a page at a time to take advantage of non-temporal
>> clear_page() implementations. However, x86_64 does not use
>> non-temporal instructions for clear_page(), and arch_clear_pmem() was
>> always incurring the cost of __arch_wb_cache_pmem().
>>
>> Clean up the assumption that doing clear_pmem() a page at a time is more
>> performant.
>
> Wouldn't another solution be to actually use non-temporal stores?
Sure.
> Why did you choose to punt?
Just a priority call at this point. Patches welcome of course ;-).
^ permalink raw reply [flat|nested] 26+ messages in thread
* Re: [PATCH v2 2/5] dax: increase granularity of dax_clear_blocks() operations
2015-10-22 21:04 ` Jeff Moyer
@ 2015-10-22 22:57 ` Williams, Dan J
2015-10-28 21:02 ` Jeff Moyer
0 siblings, 1 reply; 26+ messages in thread
From: Williams, Dan J @ 2015-10-22 22:57 UTC (permalink / raw)
To: jmoyer; +Cc: linux-kernel, linux-nvdimm, hch, akpm, axboe, jack, david, jack
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="utf-8", Size: 2680 bytes --]
On Thu, 2015-10-22 at 17:04 -0400, Jeff Moyer wrote:
> Dan Williams <dan.j.williams@intel.com> writes:
>
> > dax_clear_blocks is currently performing a cond_resched() after every
> > PAGE_SIZE memset. We need not check so frequently, for example md-raid
> > only calls cond_resched() at stripe granularity. Also, in preparation
> > for introducing a dax_map_atomic() operation that temporarily pins a dax
> > mapping move the call to cond_resched() to the outer loop.
>
> There's nothing wrong with the mechanics here, but why bother? I only
> see 1 caller in the kernel, and that caller passes in
> 1<<inode->i_blkbits for the size (so 1 page or less). Did you plan to
> add other callers? I don't see them in this particular patch set.
>
> Again, I'm not taking issue with the patch, I'm just wondering what
> motivated the change.
The motivation is the subsequent patch to wrap all touches of pmem
within a dax_map_atomic() / dax_unmap_atomic() pairing. If I just do
the straightforward conversion of this function to dax_map_atomic() it
looks something like this:
> diff --git a/fs/dax.c b/fs/dax.c
> index 5dc33d788d50..fa2a2a255d3a 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -40,9 +40,9 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
> unsigned long pfn;
> long count;
>
> - count = bdev_direct_access(bdev, sector, &addr, &pfn, size);
> - if (count < 0)
> - return count;
> + addr = __dax_map_atomic(bdev, sector, size, &pfn, &count);
> + if (IS_ERR(addr))
> + return PTR_ERR(addr);
> BUG_ON(size < count);
> while (count > 0) {
> unsigned pgsz = PAGE_SIZE - offset_in_page(addr);
> @@ -56,6 +56,7 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
> sector += pgsz / 512;
> cond_resched();
> }
> + dax_unmap_atomic(bdev, addr);
> } while (size);
>
> wmb_pmem();
The problem is that intervening call to cond_resched(). I later want to
inject an rcu_read_lock()/unlock() pair to allow flushing active
dax_map_atomic() usages at driver teardown time [1]. But, I think the
patch stands alone as a cleanup outside of that admittedly hidden
motivation.
[1]: "mm, pmem: devm_memunmap_pages(), truncate and unmap ZONE_DEVICE
pages"
https://lists.01.org/pipermail/linux-nvdimm/2015-October/002406.html
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^ permalink raw reply [flat|nested] 26+ messages in thread
* Re: [PATCH v2 1/5] pmem, dax: clean up clear_pmem()
2015-10-22 17:10 ` Dan Williams
@ 2015-10-27 17:31 ` Ross Zwisler
-1 siblings, 0 replies; 26+ messages in thread
From: Ross Zwisler @ 2015-10-27 17:31 UTC (permalink / raw)
To: Dan Williams
Cc: axboe, jack, akpm, linux-nvdimm, Dave Hansen, david,
linux-kernel, willy, ross.zwisler, hch
On Thu, Oct 22, 2015 at 01:10:21PM -0400, Dan Williams wrote:
> Both, __dax_pmd_fault, and clear_pmem() were taking special steps to
> clear memory a page at a time to take advantage of non-temporal
> clear_page() implementations. However, x86_64 does not use
> non-temporal instructions for clear_page(), and arch_clear_pmem() was
> always incurring the cost of __arch_wb_cache_pmem().
>
> Clean up the assumption that doing clear_pmem() a page at a time is more
> performant.
>
> Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
> Reported-by: Dave Hansen <dave.hansen@linux.intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
^ permalink raw reply [flat|nested] 26+ messages in thread
* Re: [PATCH v2 1/5] pmem, dax: clean up clear_pmem()
@ 2015-10-27 17:31 ` Ross Zwisler
0 siblings, 0 replies; 26+ messages in thread
From: Ross Zwisler @ 2015-10-27 17:31 UTC (permalink / raw)
To: Dan Williams
Cc: axboe, jack, akpm, linux-nvdimm, Dave Hansen, david,
linux-kernel, willy, ross.zwisler, hch
On Thu, Oct 22, 2015 at 01:10:21PM -0400, Dan Williams wrote:
> Both, __dax_pmd_fault, and clear_pmem() were taking special steps to
> clear memory a page at a time to take advantage of non-temporal
> clear_page() implementations. However, x86_64 does not use
> non-temporal instructions for clear_page(), and arch_clear_pmem() was
> always incurring the cost of __arch_wb_cache_pmem().
>
> Clean up the assumption that doing clear_pmem() a page at a time is more
> performant.
>
> Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
> Reported-by: Dave Hansen <dave.hansen@linux.intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
^ permalink raw reply [flat|nested] 26+ messages in thread
* Re: [PATCH v2 3/5] block, dax: fix lifetime of in-kernel dax mappings with dax_map_atomic()
2015-10-22 17:10 ` Dan Williams
(?)
@ 2015-10-28 20:15 ` Jeff Moyer
-1 siblings, 0 replies; 26+ messages in thread
From: Jeff Moyer @ 2015-10-28 20:15 UTC (permalink / raw)
To: Dan Williams
Cc: axboe, Jens Axboe, jack, linux-nvdimm, david, linux-kernel, hch, akpm
Dan Williams <dan.j.williams@intel.com> writes:
> The DAX implementation needs to protect new calls to ->direct_access()
> and usage of its return value against unbind of the underlying block
> device. Use blk_queue_enter()/blk_queue_exit() to either prevent
> blk_cleanup_queue() from proceeding, or fail the dax_map_atomic() if the
> request_queue is being torn down.
I don't see any problems with your changes here.
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
> Cc: Jens Axboe <axboe@kernel.dk>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Boaz Harrosh <boaz@plexistor.com>
> Cc: Dave Chinner <david@fromorbit.com>
> Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> block/blk.h | 2 -
> fs/dax.c | 165 ++++++++++++++++++++++++++++++++----------------
> include/linux/blkdev.h | 2 +
> 3 files changed, 112 insertions(+), 57 deletions(-)
>
> diff --git a/block/blk.h b/block/blk.h
> index 157c93d54dc9..dc7d9411fa45 100644
> --- a/block/blk.h
> +++ b/block/blk.h
> @@ -72,8 +72,6 @@ void blk_dequeue_request(struct request *rq);
> void __blk_queue_free_tags(struct request_queue *q);
> bool __blk_end_bidi_request(struct request *rq, int error,
> unsigned int nr_bytes, unsigned int bidi_bytes);
> -int blk_queue_enter(struct request_queue *q, gfp_t gfp);
> -void blk_queue_exit(struct request_queue *q);
> void blk_freeze_queue(struct request_queue *q);
>
> static inline void blk_queue_enter_live(struct request_queue *q)
> diff --git a/fs/dax.c b/fs/dax.c
> index f8e543839e5c..a480729c00ec 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -30,6 +30,40 @@
> #include <linux/vmstat.h>
> #include <linux/sizes.h>
>
> +static void __pmem *__dax_map_atomic(struct block_device *bdev, sector_t sector,
> + long size, unsigned long *pfn, long *len)
> +{
> + long rc;
> + void __pmem *addr;
> + struct request_queue *q = bdev->bd_queue;
> +
> + if (blk_queue_enter(q, GFP_NOWAIT) != 0)
> + return (void __pmem *) ERR_PTR(-EIO);
> + rc = bdev_direct_access(bdev, sector, &addr, pfn, size);
> + if (len)
> + *len = rc;
> + if (rc < 0) {
> + blk_queue_exit(q);
> + return (void __pmem *) ERR_PTR(rc);
> + }
> + return addr;
> +}
> +
> +static void __pmem *dax_map_atomic(struct block_device *bdev, sector_t sector,
> + long size)
> +{
> + unsigned long pfn;
> +
> + return __dax_map_atomic(bdev, sector, size, &pfn, NULL);
> +}
> +
> +static void dax_unmap_atomic(struct block_device *bdev, void __pmem *addr)
> +{
> + if (IS_ERR(addr))
> + return;
> + blk_queue_exit(bdev->bd_queue);
> +}
> +
> int dax_clear_blocks(struct inode *inode, sector_t block, long size)
> {
> struct block_device *bdev = inode->i_sb->s_bdev;
> @@ -42,9 +76,9 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
> long count, sz;
>
> sz = min_t(long, size, SZ_1M);
> - count = bdev_direct_access(bdev, sector, &addr, &pfn, sz);
> - if (count < 0)
> - return count;
> + addr = __dax_map_atomic(bdev, sector, size, &pfn, &count);
> + if (IS_ERR(addr))
> + return PTR_ERR(addr);
> if (count < sz)
> sz = count;
> clear_pmem(addr, sz);
> @@ -52,6 +86,7 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
> size -= sz;
> BUG_ON(sz & 511);
> sector += sz / 512;
> + dax_unmap_atomic(bdev, addr);
> cond_resched();
> } while (size);
>
> @@ -60,14 +95,6 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
> }
> EXPORT_SYMBOL_GPL(dax_clear_blocks);
>
> -static long dax_get_addr(struct buffer_head *bh, void __pmem **addr,
> - unsigned blkbits)
> -{
> - unsigned long pfn;
> - sector_t sector = bh->b_blocknr << (blkbits - 9);
> - return bdev_direct_access(bh->b_bdev, sector, addr, &pfn, bh->b_size);
> -}
> -
> /* the clear_pmem() calls are ordered by a wmb_pmem() in the caller */
> static void dax_new_buf(void __pmem *addr, unsigned size, unsigned first,
> loff_t pos, loff_t end)
> @@ -97,19 +124,30 @@ static bool buffer_size_valid(struct buffer_head *bh)
> return bh->b_state != 0;
> }
>
> +
> +static sector_t to_sector(const struct buffer_head *bh,
> + const struct inode *inode)
> +{
> + sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9);
> +
> + return sector;
> +}
> +
> static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
> loff_t start, loff_t end, get_block_t get_block,
> struct buffer_head *bh)
> {
> - ssize_t retval = 0;
> - loff_t pos = start;
> - loff_t max = start;
> - loff_t bh_max = start;
> - void __pmem *addr;
> + loff_t pos = start, max = start, bh_max = start;
> + struct block_device *bdev = NULL;
> + int rw = iov_iter_rw(iter), rc;
> + long map_len = 0;
> + unsigned long pfn;
> + void __pmem *addr = NULL;
> + void __pmem *kmap = (void __pmem *) ERR_PTR(-EIO);
> bool hole = false;
> bool need_wmb = false;
>
> - if (iov_iter_rw(iter) != WRITE)
> + if (rw == READ)
> end = min(end, i_size_read(inode));
>
> while (pos < end) {
> @@ -124,13 +162,13 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
> if (pos == bh_max) {
> bh->b_size = PAGE_ALIGN(end - pos);
> bh->b_state = 0;
> - retval = get_block(inode, block, bh,
> - iov_iter_rw(iter) == WRITE);
> - if (retval)
> + rc = get_block(inode, block, bh, rw == WRITE);
> + if (rc)
> break;
> if (!buffer_size_valid(bh))
> bh->b_size = 1 << blkbits;
> bh_max = pos - first + bh->b_size;
> + bdev = bh->b_bdev;
> } else {
> unsigned done = bh->b_size -
> (bh_max - (pos - first));
> @@ -138,21 +176,27 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
> bh->b_size -= done;
> }
>
> - hole = iov_iter_rw(iter) != WRITE && !buffer_written(bh);
> + hole = rw == READ && !buffer_written(bh);
> if (hole) {
> addr = NULL;
> size = bh->b_size - first;
> } else {
> - retval = dax_get_addr(bh, &addr, blkbits);
> - if (retval < 0)
> + dax_unmap_atomic(bdev, kmap);
> + kmap = __dax_map_atomic(bdev,
> + to_sector(bh, inode),
> + bh->b_size, &pfn, &map_len);
> + if (IS_ERR(kmap)) {
> + rc = PTR_ERR(kmap);
> break;
> + }
> + addr = kmap;
> if (buffer_unwritten(bh) || buffer_new(bh)) {
> - dax_new_buf(addr, retval, first, pos,
> - end);
> + dax_new_buf(addr, map_len, first, pos,
> + end);
> need_wmb = true;
> }
> addr += first;
> - size = retval - first;
> + size = map_len - first;
> }
> max = min(pos + size, end);
> }
> @@ -175,8 +219,9 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
>
> if (need_wmb)
> wmb_pmem();
> + dax_unmap_atomic(bdev, kmap);
>
> - return (pos == start) ? retval : pos - start;
> + return (pos == start) ? rc : pos - start;
> }
>
> /**
> @@ -265,28 +310,31 @@ static int dax_load_hole(struct address_space *mapping, struct page *page,
> return VM_FAULT_LOCKED;
> }
>
> -static int copy_user_bh(struct page *to, struct buffer_head *bh,
> - unsigned blkbits, unsigned long vaddr)
> +static int copy_user_bh(struct page *to, struct inode *inode,
> + struct buffer_head *bh, unsigned long vaddr)
> {
> + struct block_device *bdev = bh->b_bdev;
> void __pmem *vfrom;
> void *vto;
>
> - if (dax_get_addr(bh, &vfrom, blkbits) < 0)
> - return -EIO;
> + vfrom = dax_map_atomic(bdev, to_sector(bh, inode), bh->b_size);
> + if (IS_ERR(vfrom))
> + return PTR_ERR(vfrom);
> vto = kmap_atomic(to);
> copy_user_page(vto, (void __force *)vfrom, vaddr, to);
> kunmap_atomic(vto);
> + dax_unmap_atomic(bdev, vfrom);
> return 0;
> }
>
> static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
> struct vm_area_struct *vma, struct vm_fault *vmf)
> {
> - struct address_space *mapping = inode->i_mapping;
> - sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9);
> unsigned long vaddr = (unsigned long)vmf->virtual_address;
> - void __pmem *addr;
> + struct address_space *mapping = inode->i_mapping;
> + struct block_device *bdev = bh->b_bdev;
> unsigned long pfn;
> + void __pmem *addr;
> pgoff_t size;
> int error;
>
> @@ -305,11 +353,10 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
> goto out;
> }
>
> - error = bdev_direct_access(bh->b_bdev, sector, &addr, &pfn, bh->b_size);
> - if (error < 0)
> - goto out;
> - if (error < PAGE_SIZE) {
> - error = -EIO;
> + addr = __dax_map_atomic(bdev, to_sector(bh, inode), bh->b_size,
> + &pfn, NULL);
> + if (IS_ERR(addr)) {
> + error = PTR_ERR(addr);
> goto out;
> }
>
> @@ -317,6 +364,7 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
> clear_pmem(addr, PAGE_SIZE);
> wmb_pmem();
> }
> + dax_unmap_atomic(bdev, addr);
>
> error = vm_insert_mixed(vma, vaddr, pfn);
>
> @@ -412,7 +460,7 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
> if (vmf->cow_page) {
> struct page *new_page = vmf->cow_page;
> if (buffer_written(&bh))
> - error = copy_user_bh(new_page, &bh, blkbits, vaddr);
> + error = copy_user_bh(new_page, inode, &bh, vaddr);
> else
> clear_user_highpage(new_page, vaddr);
> if (error)
> @@ -524,11 +572,9 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
> unsigned blkbits = inode->i_blkbits;
> unsigned long pmd_addr = address & PMD_MASK;
> bool write = flags & FAULT_FLAG_WRITE;
> - long length;
> - void __pmem *kaddr;
> + struct block_device *bdev;
> pgoff_t size, pgoff;
> - sector_t block, sector;
> - unsigned long pfn;
> + sector_t block;
> int result = 0;
>
> /* Fall back to PTEs if we're going to COW */
> @@ -552,9 +598,9 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
> block = (sector_t)pgoff << (PAGE_SHIFT - blkbits);
>
> bh.b_size = PMD_SIZE;
> - length = get_block(inode, block, &bh, write);
> - if (length)
> + if (get_block(inode, block, &bh, write) != 0)
> return VM_FAULT_SIGBUS;
> + bdev = bh.b_bdev;
> i_mmap_lock_read(mapping);
>
> /*
> @@ -609,15 +655,20 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
> result = VM_FAULT_NOPAGE;
> spin_unlock(ptl);
> } else {
> - sector = bh.b_blocknr << (blkbits - 9);
> - length = bdev_direct_access(bh.b_bdev, sector, &kaddr, &pfn,
> - bh.b_size);
> - if (length < 0) {
> + long length;
> + unsigned long pfn;
> + void __pmem *kaddr = __dax_map_atomic(bdev,
> + to_sector(&bh, inode), HPAGE_SIZE, &pfn,
> + &length);
> +
> + if (IS_ERR(kaddr)) {
> result = VM_FAULT_SIGBUS;
> goto out;
> }
> - if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR))
> + if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR)) {
> + dax_unmap_atomic(bdev, kaddr);
> goto fallback;
> + }
>
> if (buffer_unwritten(&bh) || buffer_new(&bh)) {
> clear_pmem(kaddr, HPAGE_SIZE);
> @@ -626,6 +677,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
> mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
> result |= VM_FAULT_MAJOR;
> }
> + dax_unmap_atomic(bdev, kaddr);
>
> result |= vmf_insert_pfn_pmd(vma, address, pmd, pfn, write);
> }
> @@ -729,12 +781,15 @@ int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length,
> if (err < 0)
> return err;
> if (buffer_written(&bh)) {
> - void __pmem *addr;
> - err = dax_get_addr(&bh, &addr, inode->i_blkbits);
> - if (err < 0)
> - return err;
> + struct block_device *bdev = bh.b_bdev;
> + void __pmem *addr = dax_map_atomic(bdev, to_sector(&bh, inode),
> + PAGE_CACHE_SIZE);
> +
> + if (IS_ERR(addr))
> + return PTR_ERR(addr);
> clear_pmem(addr + offset, length);
> wmb_pmem();
> + dax_unmap_atomic(bdev, addr);
> }
>
> return 0;
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index cf57884db4b7..59a770dad804 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -792,6 +792,8 @@ extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t,
> extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t,
> struct scsi_ioctl_command __user *);
>
> +extern int blk_queue_enter(struct request_queue *q, gfp_t gfp);
> +extern void blk_queue_exit(struct request_queue *q);
> extern void blk_start_queue(struct request_queue *q);
> extern void blk_stop_queue(struct request_queue *q);
> extern void blk_sync_queue(struct request_queue *q);
>
> _______________________________________________
> Linux-nvdimm mailing list
> Linux-nvdimm@lists.01.org
> https://lists.01.org/mailman/listinfo/linux-nvdimm
^ permalink raw reply [flat|nested] 26+ messages in thread
* Re: [PATCH v2 4/5] block: introduce bdev_file_inode()
2015-10-22 17:10 ` Dan Williams
(?)
(?)
@ 2015-10-28 20:16 ` Jeff Moyer
-1 siblings, 0 replies; 26+ messages in thread
From: Jeff Moyer @ 2015-10-28 20:16 UTC (permalink / raw)
To: Dan Williams
Cc: axboe, jack, linux-nvdimm, david, linux-kernel, hch, Al Viro, akpm
Dan Williams <dan.j.williams@intel.com> writes:
> Similar to the file_inode() helper, provide a helper to lookup the inode for a
> raw block device itself.
>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Suggested-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
> ---
> fs/block_dev.c | 19 ++++++++++++-------
> 1 file changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index 0a793c7930eb..c1f691859a56 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -147,11 +147,16 @@ blkdev_get_block(struct inode *inode, sector_t iblock,
> return 0;
> }
>
> +static struct inode *bdev_file_inode(struct file *file)
> +{
> + return file->f_mapping->host;
> +}
> +
> static ssize_t
> blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
> {
> struct file *file = iocb->ki_filp;
> - struct inode *inode = file->f_mapping->host;
> + struct inode *inode = bdev_file_inode(file);
>
> if (IS_DAX(inode))
> return dax_do_io(iocb, inode, iter, offset, blkdev_get_block,
> @@ -329,7 +334,7 @@ static int blkdev_write_end(struct file *file, struct address_space *mapping,
> */
> static loff_t block_llseek(struct file *file, loff_t offset, int whence)
> {
> - struct inode *bd_inode = file->f_mapping->host;
> + struct inode *bd_inode = bdev_file_inode(file);
> loff_t retval;
>
> mutex_lock(&bd_inode->i_mutex);
> @@ -340,7 +345,7 @@ static loff_t block_llseek(struct file *file, loff_t offset, int whence)
>
> int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
> {
> - struct inode *bd_inode = filp->f_mapping->host;
> + struct inode *bd_inode = bdev_file_inode(filp);
> struct block_device *bdev = I_BDEV(bd_inode);
> int error;
>
> @@ -1579,14 +1584,14 @@ EXPORT_SYMBOL(blkdev_put);
>
> static int blkdev_close(struct inode * inode, struct file * filp)
> {
> - struct block_device *bdev = I_BDEV(filp->f_mapping->host);
> + struct block_device *bdev = I_BDEV(bdev_file_inode(filp));
> blkdev_put(bdev, filp->f_mode);
> return 0;
> }
>
> static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
> {
> - struct block_device *bdev = I_BDEV(file->f_mapping->host);
> + struct block_device *bdev = I_BDEV(bdev_file_inode(file));
> fmode_t mode = file->f_mode;
>
> /*
> @@ -1611,7 +1616,7 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
> ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
> {
> struct file *file = iocb->ki_filp;
> - struct inode *bd_inode = file->f_mapping->host;
> + struct inode *bd_inode = bdev_file_inode(file);
> loff_t size = i_size_read(bd_inode);
> struct blk_plug plug;
> ssize_t ret;
> @@ -1643,7 +1648,7 @@ EXPORT_SYMBOL_GPL(blkdev_write_iter);
> ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
> {
> struct file *file = iocb->ki_filp;
> - struct inode *bd_inode = file->f_mapping->host;
> + struct inode *bd_inode = bdev_file_inode(file);
> loff_t size = i_size_read(bd_inode);
> loff_t pos = iocb->ki_pos;
>
>
> _______________________________________________
> Linux-nvdimm mailing list
> Linux-nvdimm@lists.01.org
> https://lists.01.org/mailman/listinfo/linux-nvdimm
^ permalink raw reply [flat|nested] 26+ messages in thread
* Re: [PATCH v2 5/5] block: enable dax for raw block devices
2015-10-22 17:10 ` Dan Williams
(?)
@ 2015-10-28 20:50 ` Jeff Moyer
2015-10-29 7:14 ` Dan Williams
-1 siblings, 1 reply; 26+ messages in thread
From: Jeff Moyer @ 2015-10-28 20:50 UTC (permalink / raw)
To: Dan Williams
Cc: axboe, jack, linux-nvdimm, Jan Kara, david, linux-kernel,
ross.zwisler, willy, akpm, hch
Dan Williams <dan.j.williams@intel.com> writes:
> If an application wants exclusive access to all of the persistent memory
> provided by an NVDIMM namespace it can use this raw-block-dax facility
> to forgo establishing a filesystem. This capability is targeted
> primarily to hypervisors wanting to provision persistent memory for
> guests.
OK, I'm going to expose my ignorance here. :) Why does the block device
need a page_mkwrite handler?
-Jeff
> Cc: Jeff Moyer <jmoyer@redhat.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Dave Chinner <david@fromorbit.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
> Reviewed-by: Jan Kara <jack@suse.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> fs/block_dev.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 59 insertions(+), 1 deletion(-)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index c1f691859a56..210d05103657 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -1687,13 +1687,71 @@ static const struct address_space_operations def_blk_aops = {
> .is_dirty_writeback = buffer_check_dirty_writeback,
> };
>
> +#ifdef CONFIG_FS_DAX
> +/*
> + * In the raw block case we do not need to contend with truncation nor
> + * unwritten file extents. Without those concerns there is no need for
> + * additional locking beyond the mmap_sem context that these routines
> + * are already executing under.
> + *
> + * Note, there is no protection if the block device is dynamically
> + * resized (partition grow/shrink) during a fault. A stable block device
> + * size is already not enforced in the blkdev_direct_IO path.
> + *
> + * For DAX, it is the responsibility of the block device driver to
> + * ensure the whole-disk device size is stable while requests are in
> + * flight.
> + *
> + * Finally, in contrast to the generic_file_mmap() path, there are no
> + * calls to sb_start_pagefault(). That is meant to synchronize write
> + * faults against requests to freeze the contents of the filesystem
> + * hosting vma->vm_file. However, in the case of a block device special
> + * file, it is a 0-sized device node usually hosted on devtmpfs, i.e.
> + * nothing to do with the super_block for bdev_file_inode(vma->vm_file).
> + * We could call get_super() in this path to retrieve the right
> + * super_block, but the generic_file_mmap() path does not do this for
> + * the CONFIG_FS_DAX=n case.
> + */
> +static int blkdev_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
> +{
> + return __dax_fault(vma, vmf, blkdev_get_block, NULL);
> +}
> +
> +static int blkdev_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
> + pmd_t *pmd, unsigned int flags)
> +{
> + return __dax_pmd_fault(vma, addr, pmd, flags, blkdev_get_block, NULL);
> +}
> +
> +static const struct vm_operations_struct blkdev_dax_vm_ops = {
> + .page_mkwrite = blkdev_dax_fault,
> + .fault = blkdev_dax_fault,
> + .pmd_fault = blkdev_dax_pmd_fault,
> +};
> +
> +static int blkdev_mmap(struct file *file, struct vm_area_struct *vma)
> +{
> + struct inode *bd_inode = bdev_file_inode(file);
> +
> + if (!IS_DAX(bd_inode))
> + return generic_file_mmap(file, vma);
> +
> + file_accessed(file);
> + vma->vm_ops = &blkdev_dax_vm_ops;
> + vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
> + return 0;
> +}
> +#else
> +#define blkdev_mmap generic_file_mmap
> +#endif
> +
> const struct file_operations def_blk_fops = {
> .open = blkdev_open,
> .release = blkdev_close,
> .llseek = block_llseek,
> .read_iter = blkdev_read_iter,
> .write_iter = blkdev_write_iter,
> - .mmap = generic_file_mmap,
> + .mmap = blkdev_mmap,
> .fsync = blkdev_fsync,
> .unlocked_ioctl = block_ioctl,
> #ifdef CONFIG_COMPAT
^ permalink raw reply [flat|nested] 26+ messages in thread
* Re: [PATCH v2 1/5] pmem, dax: clean up clear_pmem()
2015-10-22 22:29 ` Dan Williams
@ 2015-10-28 21:01 ` Jeff Moyer
0 siblings, 0 replies; 26+ messages in thread
From: Jeff Moyer @ 2015-10-28 21:01 UTC (permalink / raw)
To: Dan Williams
Cc: Jens Axboe, Jan Kara, linux-nvdimm, Dave Hansen, david,
linux-kernel, Christoph Hellwig, Andrew Morton
Dan Williams <dan.j.williams@intel.com> writes:
> On Thu, Oct 22, 2015 at 1:48 PM, Jeff Moyer <jmoyer@redhat.com> wrote:
>> Dan Williams <dan.j.williams@intel.com> writes:
>>
>>> Both, __dax_pmd_fault, and clear_pmem() were taking special steps to
>>> clear memory a page at a time to take advantage of non-temporal
>>> clear_page() implementations. However, x86_64 does not use
>>> non-temporal instructions for clear_page(), and arch_clear_pmem() was
>>> always incurring the cost of __arch_wb_cache_pmem().
>>>
>>> Clean up the assumption that doing clear_pmem() a page at a time is more
>>> performant.
>>
>> Wouldn't another solution be to actually use non-temporal stores?
>
> Sure.
>
>> Why did you choose to punt?
>
> Just a priority call at this point. Patches welcome of course ;-).
OK. Patch is harmless.
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
^ permalink raw reply [flat|nested] 26+ messages in thread
* Re: [PATCH v2 2/5] dax: increase granularity of dax_clear_blocks() operations
2015-10-22 22:57 ` Williams, Dan J
@ 2015-10-28 21:02 ` Jeff Moyer
0 siblings, 0 replies; 26+ messages in thread
From: Jeff Moyer @ 2015-10-28 21:02 UTC (permalink / raw)
To: Williams, Dan J
Cc: linux-kernel, linux-nvdimm, hch, akpm, axboe, jack, david, jack
"Williams, Dan J" <dan.j.williams@intel.com> writes:
> The problem is that intervening call to cond_resched(). I later want to
> inject an rcu_read_lock()/unlock() pair to allow flushing active
> dax_map_atomic() usages at driver teardown time [1]. But, I think the
> patch stands alone as a cleanup outside of that admittedly hidden
> motivation.
I'm not going to split hairs.
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
^ permalink raw reply [flat|nested] 26+ messages in thread
* Re: [PATCH v2 5/5] block: enable dax for raw block devices
2015-10-28 20:50 ` Jeff Moyer
@ 2015-10-29 7:14 ` Dan Williams
0 siblings, 0 replies; 26+ messages in thread
From: Dan Williams @ 2015-10-29 7:14 UTC (permalink / raw)
To: Jeff Moyer
Cc: Jens Axboe, Jan Kara, linux-nvdimm, Jan Kara, david,
linux-kernel, Ross Zwisler, Matthew Wilcox, Andrew Morton,
Christoph Hellwig
On Thu, Oct 29, 2015 at 5:50 AM, Jeff Moyer <jmoyer@redhat.com> wrote:
> Dan Williams <dan.j.williams@intel.com> writes:
>
>> If an application wants exclusive access to all of the persistent memory
>> provided by an NVDIMM namespace it can use this raw-block-dax facility
>> to forgo establishing a filesystem. This capability is targeted
>> primarily to hypervisors wanting to provision persistent memory for
>> guests.
>
> OK, I'm going to expose my ignorance here. :) Why does the block device
> need a page_mkwrite handler?
>
You're right, it buys us nothing, and deleting it saves having to
comment on why this page_mkwrite instance is not calling
sb_start_pagefault.
^ permalink raw reply [flat|nested] 26+ messages in thread
end of thread, other threads:[~2015-10-29 7:14 UTC | newest]
Thread overview: 26+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-10-22 17:10 [PATCH v2 0/5] block, dax: updates for 4.4 Dan Williams
2015-10-22 17:10 ` Dan Williams
2015-10-22 17:10 ` [PATCH v2 1/5] pmem, dax: clean up clear_pmem() Dan Williams
2015-10-22 17:10 ` Dan Williams
2015-10-22 20:48 ` Jeff Moyer
2015-10-22 22:29 ` Dan Williams
2015-10-28 21:01 ` Jeff Moyer
2015-10-27 17:31 ` Ross Zwisler
2015-10-27 17:31 ` Ross Zwisler
2015-10-22 17:10 ` [PATCH v2 2/5] dax: increase granularity of dax_clear_blocks() operations Dan Williams
2015-10-22 17:10 ` Dan Williams
2015-10-22 21:04 ` Jeff Moyer
2015-10-22 22:57 ` Williams, Dan J
2015-10-28 21:02 ` Jeff Moyer
2015-10-22 17:10 ` [PATCH v2 3/5] block, dax: fix lifetime of in-kernel dax mappings with dax_map_atomic() Dan Williams
2015-10-22 17:10 ` Dan Williams
2015-10-28 20:15 ` Jeff Moyer
2015-10-22 17:10 ` [PATCH v2 4/5] block: introduce bdev_file_inode() Dan Williams
2015-10-22 17:10 ` Dan Williams
2015-10-22 20:37 ` Jan Kara
2015-10-22 20:37 ` Jan Kara
2015-10-28 20:16 ` Jeff Moyer
2015-10-22 17:10 ` [PATCH v2 5/5] block: enable dax for raw block devices Dan Williams
2015-10-22 17:10 ` Dan Williams
2015-10-28 20:50 ` Jeff Moyer
2015-10-29 7:14 ` Dan Williams
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