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xfs: Fix dax inode extent calculation when direct write is performed on an unwritten extent 

With dax enabled filesystems, a direct write operation into an existing
unwritten extent results in xfs_iomap_write_direct() zero-ing and converting
the extent into a normal extent before the actual data is copied from the
userspace buffer.

The inode extent count can increase by 2 if the extent range being written to
maps to the middle of the existing unwritten extent range. Hence this commit
uses XFS_IEXT_WRITE_UNWRITTEN_CNT as the extent count delta when such a write
operation is being performed.

Fixes: 727e1acd29 ("xfs: Check for extent overflow when trivally adding a new extent")
Reported-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Chandan Babu R 2021-03-25 11:48:18 -07:00 committed by Darrick J. Wong
parent 25dfa65f81
commit 5147ef30f2
1 changed files with 3 additions and 2 deletions
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5
fs/xfs/xfs_iomap.c
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@ -198,6 +198,7 @@ xfs_iomap_write_direct(
bool force = false;
int error;
int bmapi_flags = XFS_BMAPI_PREALLOC;
int nr_exts = XFS_IEXT_ADD_NOSPLIT_CNT;
ASSERT(count_fsb > 0);
@ -232,6 +233,7 @@ xfs_iomap_write_direct(
bmapi_flags = XFS_BMAPI_CONVERT | XFS_BMAPI_ZERO;
if (imap->br_state == XFS_EXT_UNWRITTEN) {
force = true;
nr_exts = XFS_IEXT_WRITE_UNWRITTEN_CNT;
dblocks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
}
}
@ -241,8 +243,7 @@ xfs_iomap_write_direct(
if (error)
return error;
error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
XFS_IEXT_ADD_NOSPLIT_CNT);
error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK, nr_exts);
if (error)
goto out_trans_cancel;