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: 727e1acd297c ("xfs: Check for extent overflow when trivally adding a new extent")
Reported-by: Darrick J. Wong <[email protected]>
Signed-off-by: Chandan Babu R <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Signed-off-by: Darrick J. Wong <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>

0 files changed, 0 insertions, 0 deletions