xfs: fix filesystsem freeze race in xfs_trans_alloc
As pointed out by Jan xfs_trans_alloc can race with a concurrent filesystem
freeze when it sleeps during the memory allocation. Fix this by moving the
wait_for_freeze call after the memory allocation. This means moving the
freeze into the low-level _xfs_trans_alloc helper, which thus grows a new
argument. Also fix up some comments in that area while at it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
Reviewed-by: Dave Chinner <david@fromorbit.com>
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 091d82b..982b711 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -688,8 +688,7 @@
* the same inode that we complete here and might deadlock
* on the iolock.
*/
- xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
- tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS);
+ tp = _xfs_trans_alloc(mp, XFS_TRANS_STRAT_WRITE, KM_NOFS, true);
tp->t_flags |= XFS_TRANS_RESERVE;
error = xfs_trans_reserve(tp, resblks,
XFS_WRITE_LOG_RES(mp), 0,