Btrfs: don't BUG() during drop snapshot

commit 4867268c57ff709a7b6b86ae6f6537d846d1443a upstream.

Really there's lots of things that can go wrong here, kill all the
BUG_ON()'s and replace the logic ones with ASSERT()'s and return EIO
instead.

Signed-off-by: Josef Bacik <jbacik@fb.com>
[ switched to btrfs_err, errors go to common label ]
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 099645ab986dd3d3b03e1aed414598290c8625fd..2af08c3de7752ee8d99555a1f5c3ad747c4a2a94 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -8486,15 +8486,13 @@ static noinline int do_walk_down(struct btrfs_trans_handle *trans,
        ret = btrfs_lookup_extent_info(trans, root, bytenr, level - 1, 1,
                                       &wc->refs[level - 1],
                                       &wc->flags[level - 1]);
-       if (ret < 0) {
-               btrfs_tree_unlock(next);
-               free_extent_buffer(next);
-               return ret;
-       }
+       if (ret < 0)
+               goto out_unlock;
 
        if (unlikely(wc->refs[level - 1] == 0)) {
                btrfs_err(root->fs_info, "Missing references.");
-               BUG();
+               ret = -EIO;
+               goto out_unlock;
        }
        *lookup_info = 0;
 
@@ -8546,7 +8544,12 @@ static noinline int do_walk_down(struct btrfs_trans_handle *trans,
        }
 
        level--;
-       BUG_ON(level != btrfs_header_level(next));
+       ASSERT(level == btrfs_header_level(next));
+       if (level != btrfs_header_level(next)) {
+               btrfs_err(root->fs_info, "mismatched level");
+               ret = -EIO;
+               goto out_unlock;
+       }
        path->nodes[level] = next;
        path->slots[level] = 0;
        path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
@@ -8561,8 +8564,15 @@ skip:
                if (wc->flags[level] & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
                        parent = path->nodes[level]->start;
                } else {
-                       BUG_ON(root->root_key.objectid !=
+                       ASSERT(root->root_key.objectid ==
                               btrfs_header_owner(path->nodes[level]));
+                       if (root->root_key.objectid !=
+                           btrfs_header_owner(path->nodes[level])) {
+                               btrfs_err(root->fs_info,
+                                               "mismatched block owner");
+                               ret = -EIO;
+                               goto out_unlock;
+                       }
                        parent = 0;
                }
 
@@ -8579,12 +8589,18 @@ skip:
                }
                ret = btrfs_free_extent(trans, root, bytenr, blocksize, parent,
                                root->root_key.objectid, level - 1, 0);
-               BUG_ON(ret); /* -ENOMEM */
+               if (ret)
+                       goto out_unlock;
        }
+
+       *lookup_info = 1;
+       ret = 1;
+
+out_unlock:
        btrfs_tree_unlock(next);
        free_extent_buffer(next);
-       *lookup_info = 1;
-       return 1;
+
+       return ret;
 }
 
 /*