From: Theodore Ts'o Subject: Re: [PATCH v2 0/4] quota: add project quota support Date: Sun, 10 Aug 2014 17:49:43 -0400 Message-ID: <20140810214943.GL15431@thunk.org> References: <20140808223335.GQ25145@thunk.org> <20140809172427.GF15431@thunk.org> <1407703644.8477.1.camel@jarvis.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Li Xi , linux-fsdevel@vger.kernel.org, Ext4 Developers List , viro@zeniv.linux.org.uk, hch@infradead.org, Jan Kara , Andreas Dilger , "Niu, Yawei" To: James Bottomley Return-path: Content-Disposition: inline In-Reply-To: <1407703644.8477.1.camel@jarvis.lan> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Sun, Aug 10, 2014 at 01:47:24PM -0700, James Bottomley wrote: > > Actually, I don't believe that's entirely accurate. The performance > problem with shared filesystem roots for containers has meant OpenVZ has > been using a block root for a while. However, we still support the old > shared filesystem root, but for quota's within the chroot, we use a subtree > quota system (not a project quota) for which Dmitry Monakhov > posted the patches several times a couple of years ago. The XFS-compatible project quota is effectively a subtree quota system. My argument is that if we're going to try to get something like this upstream, it should have the same properties as the XFS project quota system; and that should be semantically compatible with the patches you are using. (If we end up using the same ioctl's as xfs_quota uses, which in theory I'm in favor of, but which I haven't studied yet, then it might not be ABI compatible with Dmitry's patches, but it should simplify the patches that OpenVZ would need to carry.) - Ted