Hi Jan - On 1/15/16 3:35 AM, Jan Kara wrote: > On Wed 13-01-16 16:40:58, Eric Sandeen wrote: >> On 1/11/16 10:28 AM, Jan Kara wrote: ... >>> Actually, what I want from you is just an interface which is usable for VFS >>> quotas as well since I'd like to avoid adding GETQUOTA2 quotactl shortly >>> after XGETQUOTA2 :). >> >> Actually, that's exactly what I thought would *need* to happen ... we already >> have this weird 15-year-old split-brain quota interface, so if xfs and ext4 >> both need the same functionality, then we'd probably add both GETQUOTA2 and >> XGETQUOTA2. If we were doing this all from scratch, sure, but adding a new >> handles-both-quota-types interface when every other operation is already split >> between the two almost seems to make matters worse. > > Well, currently GETQUOTA and XGETQUOTA (and all the other quotactls) are > actually translated so they work regardless of the underlying filesystem. > So the only difference between XFS and VFS quotactls is in the formatting > of input/output structures. So from kernel POV it seems somewhat pointless > to add two calls doing the same thing and differing just in the formatting > of output - especially when we want the call to be extensible. > > I agree that having a unified call means having a new structure for passing > dquot info between kernel and userspace. So just for adding that one small > feature you want it seems like an overkill. But when thinking about new > extensible getquota quotactl it IMHO makes sense to unify the VFS/XFS split > brain. Thoughts? My first lazy/hacky thought is "how terrible would it be to overload the quotactl syscall return value with quota ID for Q_GETQUOTA2 calls?" For a purpose-built interface of "find the next ID" that wouldn't require any structure or interface changes... We could name it Q_GETNEXTQUOTA / Q_XGETNEXTQUOTA to make it explicit about the purpose, and document that return behavior. Done & done. ;) A new grand unified extensible quota call sounds like a great idea, I just hate to gate this work on designing a brand-new interface. -Eric -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
