[PATCH 1/2] btrfs: free fs roots on failed mount

Josef Bacik
2020-08-20T20:00:26Z

While testing a weird problem with -o degraded, I noticed I was getting
leaked root errors

BTRFS warning (device loop0): writable mount is not allowed due to too many missing devices
BTRFS error (device loop0): open_ctree failed
BTRFS error (device loop0): leaked root -9-0 refcount 1

This is the DATA_RELOC root, which gets read before the other fs roots,
but is included in the fs roots radix tree. Handle this by adding a
btrfs_drop_and_free_fs_root() on the data reloc root if it exists. This
is ok to do here if we fail further up because we will only drop the ref
if we delete the root from the radix tree, and all other cleanup won't
be duplicated.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
fs/btrfs/disk-io.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 814f8de395fe..ac6d6fddd5f4 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3418,6 +3418,8 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
btrfs_put_block_group_cache(fs_info);

fail_tree_roots:
+ if (fs_info->data_reloc_root)
+ btrfs_drop_and_free_fs_root(fs_info, fs_info->data_reloc_root);
free_root_pointers(fs_info, true);
invalidate_inode_pages2(fs_info->btree_inode->i_mapping);

--
2.24.1