From: Theodore Ts'o Subject: Re: [PATCH v2] xfstests, generic: add project quota attribute tests Date: Mon, 11 Jul 2016 13:12:42 -0400 Message-ID: <20160711171242.GA21285@thunk.org> References: <1467786171-21127-1-git-send-email-wangshilong1991@gmail.com> <20160706233533.GK27480@dastard> <20160708005127.GK12670@dastard> <20160708024654.GE19871@thunk.org> <77863b4a-95e6-4100-79c2-5cbcaf0872e7@sandeen.net> <20160708050228.GH19871@thunk.org> <20160711161556.GB9334@quack2.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Eric Sandeen , Dave Chinner , Wang Shilong , fstests@vger.kernel.org, linux-ext4@vger.kernel.org, sihara@ddn.com, lixi@ddn.com, Wang Shilong To: Jan Kara Return-path: Content-Disposition: inline In-Reply-To: <20160711161556.GB9334@quack2.suse.cz> Sender: fstests-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Mon, Jul 11, 2016 at 06:15:56PM +0200, Jan Kara wrote: > > What would you like to achieve with this? There is 'QF_META' format which > is different from 'QF_XFS' format basically only in the set of quotactls > used. As I said above it might be nice to separate kernel-api from the > underlying-quota-format but in reality these two were bound together in > older kernels so they are not really independent. The main reason why I noticed is with the new (err, "latest") ext4 quota (enabled via mke2fs -t ext4 -O quota) implementation, we enable quota tracking at mount time. (This may be true with journalled quota as well, actually). But we don't actually enable quota *enforcement* until quotaon is given. The problem is that quotaon -p prints the status of whether or not quota *tracking* is enabled, and with the new ext4 quota, quota tracking is *always* enabled. So quota -p doesn't report anything useful for new ext4 quota systems, and when I started to look at how to change things, that's when I noticed that we weren't using the new quotactl commands with ext4 even though they worked, and that the new quotactl implementation had more functionality than the older ones. BTW, I've seriously been thinking about changing the default so that if you use mke2fs -O quota, quota enforcement is also enabled by default at mount time, and we use a mount option to disable quota enforcement. If we then added a way of selectively enabling and disabling quota enforcement via quota-tools, then we would be bringing behaivour of how ext4 quota works to like how xfs treats quota. The question I have is how to do this in a way that isn't surprising for people who are used to the old behaviour --- but mke2fs -O quota is still relatively new, so maybe we could get away with it without having to add more superblock flags. - Ted