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xfs: Check for extent overflow when writing to unwritten extent

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A write to a sub-interval of an existing unwritten extent causes
the original extent to be split into 3 extents
i.e. | Unwritten | Real | Unwritten |
Hence extent count can increase by 2.

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Chandan Babu R 2021-01-22 16:48:14 -08:00 committed by Darrick J. Wong
parent 3a19bb147c
commit c442f3086d
2 changed files with 14 additions and 0 deletions
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9
fs/xfs/libxfs/xfs_inode_fork.h
View File

@ -70,6 +70,15 @@ struct xfs_ifork {
#define XFS_IEXT_ATTR_MANIP_CNT(rmt_blks) \
(XFS_DA_NODE_MAXDEPTH + max(1, rmt_blks))
/*
* A write to a sub-interval of an existing unwritten extent causes the original
* extent to be split into 3 extents
* i.e. | Unwritten | Real | Unwritten |
* Hence extent count can increase by 2.
*/
#define XFS_IEXT_WRITE_UNWRITTEN_CNT (2)
/*
* Fork handling.
*/

5
fs/xfs/xfs_iomap.c
View File

@ -566,6 +566,11 @@ xfs_iomap_write_unwritten(
if (error)
goto error_on_bmapi_transaction;
error = xfs_iext_count_may_overflow(ip, XFS_DATA_FORK,
XFS_IEXT_WRITE_UNWRITTEN_CNT);
if (error)
goto error_on_bmapi_transaction;
/*
* Modify the unwritten extent state of the buffer.
*/