btrfs: hold a ref on the root in resolve_indirect_ref

We're looking up a random root, we need to hold a ref on it while we're
using it.

Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index e5d85311d5d5d4eadd857fda99a99bd881074b38..193747b6e1f92d4be9d39d7d2e4add40447383a5 100644 (file)
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -524,7 +524,13 @@ static int resolve_indirect_ref(struct btrfs_fs_info *fs_info,
        if (IS_ERR(root)) {
                srcu_read_unlock(&fs_info->subvol_srcu, index);
                ret = PTR_ERR(root);
-               goto out;
+               goto out_free;
+       }
+
+       if (!btrfs_grab_fs_root(root)) {
+               srcu_read_unlock(&fs_info->subvol_srcu, index);
+               ret = -ENOENT;
+               goto out_free;
        }
 
        if (btrfs_is_testing(fs_info)) {
@@ -577,6 +583,8 @@ static int resolve_indirect_ref(struct btrfs_fs_info *fs_info,
        ret = add_all_parents(root, path, parents, ref, level, time_seq,
                              extent_item_pos, total_refs, ignore_offset);
 out:
+       btrfs_put_fs_root(root);
+out_free:
        path->lowest_level = 0;
        btrfs_release_path(path);
        return ret;