Btrfs: do not BUG_ON in prepare_to_reloc

We can bail out from here gracefully instead of a cold BUG_ON.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 7d1654cf9d48..9d13786eec73 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -3731,7 +3731,15 @@ int prepare_to_relocate(struct reloc_control *rc)
         set_reloc_control(rc);
 
         trans = btrfs_join_transaction(rc->extent_root);
-        BUG_ON(IS_ERR(trans));
+        if (IS_ERR(trans)) {
+                unset_reloc_control(rc);
+                /*
+                 * extent tree is not a ref_cow tree and has no reloc_root to
+                 * cleanup.  And callers are responsible to free the above
+                 * block rsv.
+                 */
+                return PTR_ERR(trans);
+        }
         btrfs_commit_transaction(trans, rc->extent_root);
         return 0;
 }