btrfs: fix return value check of btrfs_start_transaction()

The error check of btrfs_start_transaction() is added, and the mistake
of the error check on several places is corrected.

Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index f4e45fdded30..0209b5fc772c 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -623,6 +623,8 @@ int btrfs_sync_fs(struct super_block *sb, int wait)
         btrfs_wait_ordered_extents(root, 0, 0);
 
         trans = btrfs_start_transaction(root, 0);
+        if (IS_ERR(trans))
+                return PTR_ERR(trans);
         ret = btrfs_commit_transaction(trans, root);
         return ret;
 }