Q_XGETNEXTQUOTA: API for fast querying of quota for uid ranges

[arekm]

Linux kernel supports feature that allows for fast and efficient querying of all quota in the filesystem.

It's Q_XGETNEXTQUOTA ioctl.

https://patchwork.kernel.org/project/linux-fsdevel/patch/1453487136-12681-3-git-send-email-sandeen@redhat.com/

This is feature request about adding support for it.

As simple API like:

(uid, bcount, bsoft, bhard, btime, icount, isoft, ihard, itime) = qObj.querynext(uid [,grpquota=1] [,prjquota=1])

or more complicated like

queryrange(uid, uid_last=False,...)

returning dictionary of uids with their quota tuples (or something like that)

For systems that don't support this feature it could be emulated by iterating from uid to (uid_t)-1 until found but... that can be a lot (if for example there is no single uid with quotas above our called uid). Or just FsQuota.error(ENOTSUP).