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_trans.c b/fs/xfs/xfs_trans.c
index c83f63b..2837220 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -566,31 +566,24 @@
/*
* This routine is called to allocate a transaction structure.
+ *
* The type parameter indicates the type of the transaction. These
* are enumerated in xfs_trans.h.
- *
- * Dynamically allocate the transaction structure from the transaction
- * zone, initialize it, and return it to the caller.
*/
-xfs_trans_t *
-xfs_trans_alloc(
- xfs_mount_t *mp,
- uint type)
-{
- xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
- return _xfs_trans_alloc(mp, type, KM_SLEEP);
-}
-
-xfs_trans_t *
+struct xfs_trans *
_xfs_trans_alloc(
- xfs_mount_t *mp,
- uint type,
- uint memflags)
+ struct xfs_mount *mp,
+ uint type,
+ uint memflags,
+ bool wait_for_freeze)
{
- xfs_trans_t *tp;
+ struct xfs_trans *tp;
atomic_inc(&mp->m_active_trans);
+ if (wait_for_freeze)
+ xfs_wait_for_freeze(mp, SB_FREEZE_TRANS);
+
tp = kmem_zone_zalloc(xfs_trans_zone, memflags);
tp->t_magic = XFS_TRANS_MAGIC;
tp->t_type = type;