Btrfs: fix race in sync and freeze again
I screwed this up, there is a race between checking if there is a running
transaction and actually starting a transaction in sync where we could race
with a freezer and get ourselves into trouble. To fix this we need to make
a new join type to only do the try lock on the freeze stuff. If it fails
we'll return EPERM and just return from sync. This fixes a hang Liu Bo
reported when running xfstest 68 in a loop. Thanks,
Reported-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 867e8e7..903ab2d 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -854,16 +854,13 @@
btrfs_wait_ordered_extents(root, 0, 0);
- spin_lock(&fs_info->trans_lock);
- if (!fs_info->running_transaction) {
- spin_unlock(&fs_info->trans_lock);
- return 0;
- }
- spin_unlock(&fs_info->trans_lock);
-
- trans = btrfs_join_transaction(root);
- if (IS_ERR(trans))
+ trans = btrfs_join_transaction_freeze(root);
+ if (IS_ERR(trans)) {
+ /* Frozen, don't bother */
+ if (PTR_ERR(trans) == -EPERM)
+ return 0;
return PTR_ERR(trans);
+ }
return btrfs_commit_transaction(trans, root);
}