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Commit 4df0f7f1 authored by Dave Chinner's avatar Dave Chinner Committed by Darrick J. Wong
Browse files

xfs: fix transaction allocation deadlock in IO path 



xfs_trans_alloc() does GFP_KERNEL allocation, and we can call it
while holding pages locked for writeback in the ->writepages path.
The memory allocation is allowed to wait on pages under writeback,
and so can wait on pages that are tagged as writeback by the
caller.

This affects both pre-IO submission and post-IO submission paths.
Hence xfs_setsize_trans_alloc(), xfs_reflink_end_cow(),
xfs_iomap_write_unwritten() and xfs_reflink_cancel_cow_range().
xfs_iomap_write_unwritten() already does the right thing, but the
others don't. Fix them.

Signed-Off-By: default avatarDave Chinner <dchinner@redhat.com>
Fixes: 281627df ("xfs: log file size updates at I/O completion time")
Fixes: 43caeb18 ("xfs: move mappings from cow fork to data fork after copy-write)"
Reviewed-by: default avatarEric Sandeen <sandeen@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent c3b1b131

fs/xfs/xfs_aops.c

+2 −1
Original line number Diff line number Diff line
@@ -209,7 +209,8 @@ xfs_setfilesize_trans_alloc( 
	struct xfs_trans	*tp;

	int			error;



	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp);

	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0,

				XFS_TRANS_NOFS, &tp);

	if (error)

		return error;

fs/xfs/xfs_reflink.c

+2 −2
Original line number Diff line number Diff line
@@ -668,7 +668,7 @@ xfs_reflink_cancel_cow_range( 


	/* Start a rolling transaction to remove the mappings */

	error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,

			0, 0, 0, &tp);

			0, 0, XFS_TRANS_NOFS, &tp);

	if (error)

		goto out;
@@ -741,7 +741,7 @@ xfs_reflink_end_cow( 
			(unsigned int)(end_fsb - offset_fsb),

			XFS_DATA_FORK);

	error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,

			resblks, 0, XFS_TRANS_RESERVE, &tp);

			resblks, 0, XFS_TRANS_RESERVE | XFS_TRANS_NOFS, &tp);

	if (error)

		goto out;