Re: File test operator for subvols; possible bug in 'btrfs show <directory>'

[Goffredo Baroncelli <kreijack@inwind.it>]

On 11/25/2014 03:11 AM, boris wrote:
> Hi all,
> 
> I was looking for a quick method of testing whether a working directory is a 
> subvolume.

Currently btrfs check that:
- the inode number is 255
- the path is a directory

>From cmds-subvolume.c

[...]
/*
 * test if path is a subvolume:
 * this function return
 * 0-> path exists but it is not a subvolume
 * 1-> path exists and it is  a subvolume
 * -1 -> path is unaccessible
 */
int test_issubvolume(char *path)
{
        struct stat     st;
        int             res;

        res = stat(path, &st);
        if(res < 0 )
                return -1;

        return (st.st_ino == 256) && S_ISDIR(st.st_mode);
}
[---]
> 
> Couldn't see an obvious one, so tried 'btrfs show <somesubvol≥'. It printed 
> a fail message as expected but returned 0 exit status. Bug?
> 
> Can I put in a feature request for a shell file test operator for subvols, 
> please (or something of the kind)? http://tldp.org/LDP/abs/html/fto.html . 
> The letter v (for volume, both upper and lower case forms; one for subvol, 
> other for snapshots) is unused afaict. 
> 
> Have I missed the obvious? Or scored a false positive?
> 
> TIA.
> 
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