Commit c442f308 authored Jan 22, 2021 by Chandan Babu R Committed by Darrick J. Wong Jan 22, 2021

xfs: Check for extent overflow when writing to unwritten extent



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>

parent 3a19bb14

fs/xfs/libxfs/xfs_inode_fork.h

+9 −0

Original line number	Diff line number	Diff line
		@@ -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.
		*/

fs/xfs/xfs_iomap.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -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.
		*/