On Mon, Mar 04, 2019 at 10:16:29PM +0100, Michael Kerrisk (man-pages) wrote: > Hi Dave, > On Mon, 4 Mar 2019 at 21:50, Dave Chinner <david@xxxxxxxxxxxxx> wrote: > > > > On Mon, Mar 04, 2019 at 02:52:59PM +0100, Michael Kerrisk (man-pages) wrote: > > > Hello Wang Shilong, > > > > > > On Fri, 1 Mar 2019 at 15:06, Wang Shilong <wangshilong1991@xxxxxxxxx> wrote: > > > > > > > > From: Wang Shilong <wshilong@xxxxxxx> > > > > > > I take it that these patches relate to some API changes that are not > > > yet merged into the kernel, right? > > > > > > Also, I think we need some accompanying info to describe project IDs. > > > Can you point me at any documents/resources? > > > > Probably "best" documented in the man pages that ship with xfsprogs. > > But, these IDs are a kernel construct, right? On disk filesystem format construct, actually. The kernel doesn't use them for anything other than filesystem quota accounting - it's completely oblivious to the meaning of the IDs (unlike uids and gids used for user and group quota accounting). > Is their scope limited > just to XFS, or do other filesystems have the concept also? Originally only XFS. Irix implemented project quotas rather than group quotas, IIRC, in the late 80s/early 90s(*) so XFS supported project quotas for day zero. I think is was 2004/2005 that they were fully supported on Linux (using an exclusive group or project quota requirement) and with v5 filesystems we added a third quota inode so we can have user, group and project quotas all active on a filesystem at once. 2-3 years ago project quotas were added to ext4 and so anything that uses the generic kernel quota infrastructure can implement it, too. Cheers, Dave. (*) In some ways, we are still dragging Linux into the '80s, kicking and screaming all the way :P -- Dave Chinner david@xxxxxxxxxxxxx
