btrfs: hold a ref on the root in btrfs_check_uuid_tree_entry

We lookup the uuid of arbitrary subvolumes, hold a ref on the root while
we're doing this.

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/volumes.c b/fs/btrfs/volumes.c
index 0b3167b..3fca9f9 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4431,6 +4431,10 @@ static int btrfs_check_uuid_tree_entry(struct btrfs_fs_info *fs_info,
                        ret = 1;
                goto out;
        }
+       if (!btrfs_grab_fs_root(subvol_root)) {
+               ret = 1;
+               goto out;
+       }
 
        switch (type) {
        case BTRFS_UUID_KEY_SUBVOL:
@@ -4443,7 +4447,7 @@ static int btrfs_check_uuid_tree_entry(struct btrfs_fs_info *fs_info,
                        ret = 1;
                break;
        }
-
+       btrfs_put_fs_root(subvol_root);
 out:
        return ret;
 }