Btrfs: don't BUG() during drop snapshot

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>

1 files changed, 27 insertions, 11 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index a23597f6d3cd..11802eaaab54 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -8886,15 +8886,13 @@ 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;
 
@@ -8946,7 +8944,12 @@ 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;
@@ -8961,8 +8964,15 @@ 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;
                 }
 
@@ -8977,12 +8987,18 @@ 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;
 }
 
 /*