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: 281627df3eb5 ("xfs: log file size updates at I/O completion time")
Fixes: 43caeb187deb9 ("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>

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 9c6a830da0eec4663c04b5c58606962139598890..a0afb6411417d49e60e8cfec2fdabc7e84b12895 100644 (file)
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -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;
 

diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 270246943a065fff8224b36b225e2572e213ef05..8c16177b33d445a9d277d528064d54e2bb1b63b1 100644 (file)
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -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;