btrfs: free btrfs_path before copying subvol info to userspace

commit 013c1c5 upstream.

btrfs_ioctl_get_subvol_info() frees the search path after the userspace
copy from the temp buffer @subvol_info. This can lead to a lock splat
warning.

Fix this by freeing the path before we copy it to userspace.

CC: stable@vger.kernel.org # 4.19+
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/btrfs/ioctl.c

@@ -2788,6 +2788,8 @@ static int btrfs_ioctl_get_subvol_info(struct file *file, void __user *argp)
  }
  }
 
+ btrfs_free_path(path);
+ path = NULL;
  if (copy_to_user(argp, subvol_info, sizeof(*subvol_info)))
  ret = -EFAULT;