diff mbox series

[v4,6/9] iomap: don't increase i_size if it's not a write operation

Message ID 20240320110548.2200662-7-yi.zhang@huaweicloud.com (mailing list archive)
State New
Headers show
Series xfs/iomap: fix non-atomic clone operation and don't update size when zeroing range post eof | expand

Commit Message

Zhang Yi March 20, 2024, 11:05 a.m. UTC 
From: Zhang Yi <yi.zhang@huawei.com>

Increase i_size in iomap_zero_range() and iomap_unshare_iter() is not
needed, the caller should handle it. Especially, when truncate partial
block, we should not increase i_size beyond the new EOF here. It doesn't
affect xfs and gfs2 now because they set the new file size after zero
out, it doesn't matter that a transient increase in i_size, but it will
affect ext4 because it set file size before truncate. So move the i_size
updating logic to iomap_write_iter().

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/iomap/buffered-io.c | 50 +++++++++++++++++++++---------------------
 1 file changed, 25 insertions(+), 25 deletions(-)

Comments

Chandan Babu R April 19, 2024, 6:07 a.m. UTC | #1 
On Wed, Mar 20, 2024 at 07:05:45 PM +0800, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@huawei.com>
>
> Increase i_size in iomap_zero_range() and iomap_unshare_iter() is not
> needed, the caller should handle it. Especially, when truncate partial
> block, we should not increase i_size beyond the new EOF here. It doesn't
> affect xfs and gfs2 now because they set the new file size after zero
> out, it doesn't matter that a transient increase in i_size, but it will
> affect ext4 because it set file size before truncate. So move the i_size
> updating logic to iomap_write_iter().
>

This patch causes generic/522 to consistently fail when using the following
fstest configuration,

TEST_DEV=/dev/loop16
TEST_LOGDEV=/dev/loop13
SCRATCH_DEV_POOL="/dev/loop5 /dev/loop6 /dev/loop7 /dev/loop8 /dev/loop9 /dev/loop10 /dev/loop11 /dev/loop12"
MKFS_OPTIONS='-f -m reflink=1,rmapbt=1, -i sparse=1, -lsize=1g'
MOUNT_OPTIONS='-o usrquota,grpquota,prjquota'
TEST_FS_MOUNT_OPTS="$TEST_FS_MOUNT_OPTS -o usrquota,grpquota,prjquota"
TEST_FS_MOUNT_OPTS="-o logdev=/dev/loop13"
SCRATCH_LOGDEV=/dev/loop15
USE_EXTERNAL=yes
LOGWRITES_DEV=/dev/loop15
Zhang Yi April 19, 2024, 8:14 a.m. UTC | #2 
On 2024/4/19 14:07, Chandan Babu R wrote:
> On Wed, Mar 20, 2024 at 07:05:45 PM +0800, Zhang Yi wrote:
>> From: Zhang Yi <yi.zhang@huawei.com>
>>
>> Increase i_size in iomap_zero_range() and iomap_unshare_iter() is not
>> needed, the caller should handle it. Especially, when truncate partial
>> block, we should not increase i_size beyond the new EOF here. It doesn't
>> affect xfs and gfs2 now because they set the new file size after zero
>> out, it doesn't matter that a transient increase in i_size, but it will
>> affect ext4 because it set file size before truncate. So move the i_size
>> updating logic to iomap_write_iter().
>>
> 
> This patch causes generic/522 to consistently fail when using the following
> fstest configuration,
> 
> TEST_DEV=/dev/loop16
> TEST_LOGDEV=/dev/loop13
> SCRATCH_DEV_POOL="/dev/loop5 /dev/loop6 /dev/loop7 /dev/loop8 /dev/loop9 /dev/loop10 /dev/loop11 /dev/loop12"
> MKFS_OPTIONS='-f -m reflink=1,rmapbt=1, -i sparse=1, -lsize=1g'
> MOUNT_OPTIONS='-o usrquota,grpquota,prjquota'
> TEST_FS_MOUNT_OPTS="$TEST_FS_MOUNT_OPTS -o usrquota,grpquota,prjquota"
> TEST_FS_MOUNT_OPTS="-o logdev=/dev/loop13"
> SCRATCH_LOGDEV=/dev/loop15
> USE_EXTERNAL=yes
> LOGWRITES_DEV=/dev/loop15
> 

Sorry for the regression, I didn't notice this issue last time I ran
this test. It looks like the 004 patch doesn't work for some cases.
I can reproduce it on my machine now, and I'll take a look at this
and fix it soon.

Thanks,
Yi.
Zhang Yi April 23, 2024, 11:30 a.m. UTC | #3 
On 2024/4/19 14:07, Chandan Babu R wrote:
> On Wed, Mar 20, 2024 at 07:05:45 PM +0800, Zhang Yi wrote:
>> From: Zhang Yi <yi.zhang@huawei.com>
>>
>> Increase i_size in iomap_zero_range() and iomap_unshare_iter() is not
>> needed, the caller should handle it. Especially, when truncate partial
>> block, we should not increase i_size beyond the new EOF here. It doesn't
>> affect xfs and gfs2 now because they set the new file size after zero
>> out, it doesn't matter that a transient increase in i_size, but it will
>> affect ext4 because it set file size before truncate. So move the i_size
>> updating logic to iomap_write_iter().
>>
> 
> This patch causes generic/522 to consistently fail when using the following
> fstest configuration,
> 
> TEST_DEV=/dev/loop16
> TEST_LOGDEV=/dev/loop13
> SCRATCH_DEV_POOL="/dev/loop5 /dev/loop6 /dev/loop7 /dev/loop8 /dev/loop9 /dev/loop10 /dev/loop11 /dev/loop12"
> MKFS_OPTIONS='-f -m reflink=1,rmapbt=1, -i sparse=1, -lsize=1g'
> MOUNT_OPTIONS='-o usrquota,grpquota,prjquota'
> TEST_FS_MOUNT_OPTS="$TEST_FS_MOUNT_OPTS -o usrquota,grpquota,prjquota"
> TEST_FS_MOUNT_OPTS="-o logdev=/dev/loop13"
> SCRATCH_LOGDEV=/dev/loop15
> USE_EXTERNAL=yes
> LOGWRITES_DEV=/dev/loop15
> 

Hello!

The root cause of the problem is caused by patch 4/9, this patch is fine,
I've revised the patch 4/9 and send it out separately in reply to v4. I've
tested that on my machine for over 100 rounds on generic/522 and it hasn't
failed again. Please take a look at the v5 patch for details and test it
on your machine.

https://lore.kernel.org/linux-xfs/20240423111735.1298851-1-yi.zhang@huaweicloud.com/T/#m2da33e643b642071aa20077321e2c431f5a64e38

Thanks,
Yi.
diff mbox series

Patch

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 7e32a204650b..e9112dc78d15 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -837,32 +837,13 @@  static size_t iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len,
 		size_t copied, struct folio *folio)
 {
 	const struct iomap *srcmap = iomap_iter_srcmap(iter);
-	loff_t old_size = iter->inode->i_size;
-	size_t ret;
-
-	if (srcmap->type == IOMAP_INLINE) {
-		ret = iomap_write_end_inline(iter, folio, pos, copied);
-	} else if (srcmap->flags & IOMAP_F_BUFFER_HEAD) {
-		ret = block_write_end(NULL, iter->inode->i_mapping, pos, len,
-				copied, &folio->page, NULL);
-	} else {
-		ret = __iomap_write_end(iter->inode, pos, len, copied, folio);
-	}
-
-	/*
-	 * Update the in-memory inode size after copying the data into the page
-	 * cache.  It's up to the file system to write the updated size to disk,
-	 * preferably after I/O completion so that no stale data is exposed.
-	 */
-	if (pos + ret > old_size) {
-		i_size_write(iter->inode, pos + ret);
-		iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;
-	}
-	__iomap_put_folio(iter, pos, ret, folio);
 
-	if (old_size < pos)
-		pagecache_isize_extended(iter->inode, old_size, pos);
-	return ret;
+	if (srcmap->type == IOMAP_INLINE)
+		return iomap_write_end_inline(iter, folio, pos, copied);
+	if (srcmap->flags & IOMAP_F_BUFFER_HEAD)
+		return block_write_end(NULL, iter->inode->i_mapping, pos, len,
+				       copied, &folio->page, NULL);
+	return __iomap_write_end(iter->inode, pos, len, copied, folio);
 }
 
 static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
@@ -877,6 +858,7 @@  static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
 
 	do {
 		struct folio *folio;
+		loff_t old_size;
 		size_t offset;		/* Offset into folio */
 		size_t bytes;		/* Bytes to write to folio */
 		size_t copied;		/* Bytes copied from user */
@@ -926,6 +908,22 @@  static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
 		copied = copy_folio_from_iter_atomic(folio, offset, bytes, i);
 		status = iomap_write_end(iter, pos, bytes, copied, folio);
 
+		/*
+		 * Update the in-memory inode size after copying the data into
+		 * the page cache.  It's up to the file system to write the
+		 * updated size to disk, preferably after I/O completion so that
+		 * no stale data is exposed.  Only once that's done can we
+		 * unlock and release the folio.
+		 */
+		old_size = iter->inode->i_size;
+		if (pos + status > old_size) {
+			i_size_write(iter->inode, pos + status);
+			iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;
+		}
+		__iomap_put_folio(iter, pos, status, folio);
+
+		if (old_size < pos)
+			pagecache_isize_extended(iter->inode, old_size, pos);
 		if (status < bytes)
 			iomap_write_failed(iter->inode, pos + status,
 					   bytes - status);
@@ -1298,6 +1296,7 @@  static loff_t iomap_unshare_iter(struct iomap_iter *iter)
 			bytes = folio_size(folio) - offset;
 
 		bytes = iomap_write_end(iter, pos, bytes, bytes, folio);
+		__iomap_put_folio(iter, pos, bytes, folio);
 		if (WARN_ON_ONCE(bytes == 0))
 			return -EIO;
 
@@ -1362,6 +1361,7 @@  static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)
 		folio_mark_accessed(folio);
 
 		bytes = iomap_write_end(iter, pos, bytes, bytes, folio);
+		__iomap_put_folio(iter, pos, bytes, folio);
 		if (WARN_ON_ONCE(bytes == 0))
 			return -EIO;