On Fri, Jan 15, 2016 at 10:35:07AM +0100, Jan Kara wrote: > On Wed 13-01-16 16:40:58, Eric Sandeen wrote: > > 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? A new unified userspace quota API would be nice, but it's a completely separate piece of work. We'd also need to do userspace work to support it, so I think this is a valid medium term goal, but not somethign that should gate the work Eric is doing. i.e. it might be best to introduce a quotactl2 syscall for a unified interface, such that the syscall itself has a flags argument rather than having to jump through hoops to embed flags in argument structures..... FWIW, converting xfs_quota to use a new kernel API is trivial (half an hour's work) as it already has a kernel API abstraction layer for cross platform support. Hence we can quickly get userspace support in place to test such a new kernel API... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- 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
