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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: Dave Chinner <dchinner@redhat.com>
Fixes: 281627df3e ("xfs: log file size updates at I/O completion time")
Fixes: 43caeb187d ("xfs: move mappings from cow fork to data fork after copy-write)"
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Dave Chinner 2018-03-06 17:07:22 -08:00 committed by Darrick J. Wong
parent c3b1b13190
commit 4df0f7f145
2 changed files with 4 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
fs/xfs/xfs_aops.c
View File

@ -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;

4
fs/xfs/xfs_reflink.c
View File

@ -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;