[Libvir] Re: parted/LVM for ET [Storage manager initial requirements and thoughts

[Jim Meyering]

"Daniel P. Berrange" <berrange at redhat.com> wrote:
>> > And (4) can be done by libvirtd using ordinary POSIX calls, so no
>> > external library support is needed, just some work to remote those
>> > operations (which is mostly done).
>>
>> Isn't doing #4 portably pretty tricky?  There's still too much
>> variation, because many of the details aren't covered by POSIX.
>> At least for GNU df, it was -- it uses the mountlist module from gnulib:
>
> We don't need to enumerate all the mount points. The admin will simply

Lucky you :)

> configure particulra directories (eg /var/lib/xen/images) as storage
> repositories. So we only need to be able to call statfs/statvfs on
> particular paths where we want to create a new image.
>
>> Of course, if your target is just Linux, then it is easier.
>
> Minimally we have to target Solaris too, since we know they already use
> libvirt.

Ok.  Then this (also used by df) might help, if you ever
need portability to e.g., older Solaris, *BSD, AIX, HP-UX, etc.

http://cvs.sv.gnu.org/viewcvs/gnulib/lib/fsusage.c?root=gnulib&view=markup

It provides a thin wrapper around statfs/statvfs, which helps handle
some of the bogus values (sometimes negative or UINTMAX_MAX) that can
arise in statvfs.f_* values.  That last bit might even be useful on Linux.