btrfs: Don't BUG_ON errors from update_ref_for_cow()

__btrfs_cow_block(), the only caller of update_ref_for_cow() will BUG_ON()
any error return.  Instead, we can go read-only fs as update_ref_for_cow()
manipulates disk data in a way which doesn't look like it's easily rolled
back.

Signed-off-by: Mark Fasheh <mfasheh@suse.de>

1 files changed, 4 insertions, 1 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 3b767d2b68e8..36e16bd50798 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -474,7 +474,10 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
                             BTRFS_FSID_SIZE);
 
         ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
-        BUG_ON(ret);
+        if (ret) {
+                btrfs_std_error(root->fs_info, ret);
+                return ret;
+        }
 
         if (root->ref_cows)
                 btrfs_reloc_cow_block(trans, root, buf, cow);