btrfs-progs: inspect rootid: Allow a file to be specified
Since cmd_inspect_rootid() calls btrfs_open_dir(), it rejects a file to
be specified. But as the document says, a file should be supported.
This patch introduces btrfs_open_file_or_dir(), which is a counterpart
of btrfs_open_dir(), to safely check and open btrfs file or directory.
The original btrfs_open_dir() content is moved to btrfs_open() and shared
by both function.
Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>