Subvolume::get() works if given a path not at the root of a subvolume, contrary to comment

[agrover]

    /// Get a subvolume.
    ///
    /// The path must point to the root of a subvolume.

I tried calling Subvolume::get() with the path to a normal directory on a btrfs filesystem and it worked, contrary to what the above comment says. I'm not sure if the code, or the comment, needs to be changed.

[cezarmathe]

then it seems like btrfs_util_is_subvolume is returning true even if the path is not the root of a subvolume. I think one way to solve this issue is to cannonicalize the path and then check if stripping the last path component yields the same subvolume id, a different id, or returns either the NOT_SUBVOLUME or the NOT_BTRFS subvolume.