From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dongsheng Yang Subject: Re: [PATCH v3 36/39] ubifs: implement ubifs_get_qsize to get quota size in ubifs Date: Mon, 21 Sep 2015 19:02:30 +0800 Message-ID: <55FFE3C6.2020609@cn.fujitsu.com> References: <1442307754-13233-1-git-send-email-yangds.fnst@cn.fujitsu.com> <1442307754-13233-37-git-send-email-yangds.fnst@cn.fujitsu.com> <20150916100007.GD13325@quack.suse.cz> <55FA6A5F.1010702@cn.fujitsu.com> <20150917120044.GC32280@quack.suse.cz> <55FBABD8.9030002@cn.fujitsu.com> <20150918112006.GA16306@quack.suse.cz> <55FF88F5.5070703@cn.fujitsu.com> <20150921091355.GA9028@quack.suse.cz> <55FFCB01.9070205@cn.fujitsu.com> <20150921094452.GC9028@quack.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Cc: , , , , To: Jan Kara Return-path: Received: from cn.fujitsu.com ([59.151.112.132]:31884 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753846AbbIULI4 (ORCPT ); Mon, 21 Sep 2015 07:08:56 -0400 In-Reply-To: <20150921094452.GC9028@quack.suse.cz> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On 09/21/2015 05:44 PM, Jan Kara wrote: > On Mon 21-09-15 17:16:49, Dongsheng Yang wrote: >> On 09/21/2015 05:13 PM, Jan Kara wrote: >>> On Mon 21-09-15 12:35:01, Dongsheng Yang wrote: >>>> On 09/18/2015 07:20 PM, Jan Kara wrote: >>>>>> .... TBH, there is a little different with other filesystems. I did not >>>>>> use the "disk" space, but the file space in ubifs quota, although dquot >>>>>> means disk quota. Same with btrfs quota. If we use disk space for quota, >>>>>> the most common problem from user is that: why I did not reach the limit >>>>>> but I can not write any byte. COW in btrfs or out-place-updating in >>>>>> ubifs makes this problem much worse. >>>>>> >>>>>> So I choose file space here for ubifs. >>>>> >>>>> OK, so these are really two separate questions. I understand your choice of >>>>> using file space as the amount of space to account for quota purposes and >>>>> I'm fine with that choice. Another thing is that regardless of how you >>>>> decide to do quota accounting, you must maintain i_blocks / i_bytes to >>>>> contain proper value because dquot_transfer() uses that information to update >>>>> quota usage when inode owner is changed. >>>> >>>> But if we don't use i_blocks to get qsize, what we care only in >>>> dquot_transter() is dquot->dq_dqb. That means, even if the i_blocks >>>> is not correct in dquot_transfer() in ubifs, that's okey, because we >>>> will never use this value, right? >>> >>> dquot_transfer() will use the value - when file F changes owner from user A >>> to user B, then you need to decrement amount of space used by F from A's >>> quota usage and add that amount to B's quota usage. And the amount of space >>> is obtained via inode_get_bytes() which uses i_blocks and i_bytes. See >>> __dquot_transfer() in fs/quota/dquot.c for details. >> >> Yes, I see it. But if ubifs doesn't use i_blocks and i_bytes to stand >> for quota size, as I mentioned I want to use i_size. Then we will never >> use i_blocks. So we only need a to transfer dquot->dq_dqb values. That >> means, even the i_blocks in dquot_transfer() is not correct, we don't >> care it. we only need to make sure values in dquot_dq_dqb are >> transfered, such as dquot->dq_dqb->curspace for user B is equal with >> i_size. > > I think you are missing one thing: > > Assume user A has files F1 (1MB) F2 (2MB) F3 (3MB). > User B has one file G1 (4MB). > > So user A uses 6 MB in total (stored in dquot for user A in dqb_curspace > field). User B uses 4MB. > > Now you do "chown B F1" > > You need to change dq_dqb of F1 to point to user B quota structure as you > explain, that is correct. However you also need to subtract 1MB from user > A's total usage (which is stored in struct dquot for user A) since file F1 > no longer belongs to him. And you need to add 1 MB to user B's total usage. > > After this user A will have total usage of 5 MB and user B has usage of 5 > MB as well. You need to properly update the total usage of each user so > that you can check the usage against quota limits. But that's all done in dquot_transfer(). It dquot_decr_space(from) and dquot_incr_space(to). Let me show the test result in my implementation. (1). root -> 1M/2M/3M yds ->4M [root@atest-guest linux_compile]# ll -h /mnt/ubifs/ total 11M -rw-r--r--. 1 root root 1.0M Sep 21 15:54 1M -rw-r--r--. 1 root root 2.0M Sep 21 15:54 2M -rw-r--r--. 1 root root 3.0M Sep 21 15:54 3M -rw-r--r--. 1 yds root 4.0M Sep 21 15:55 4M -rw-------. 1 root root 6.0K Sep 21 15:53 aquota.group -rw-------. 1 root root 7.0K Sep 21 15:53 aquota.user [root@atest-guest linux_compile]# repquota -u /mnt/ubifs/ *** Report for user quotas on device /dev/ubi0_0 Block grace time: 7days; Inode grace time: 7days Block limits File limits User used soft hard grace used soft hard grace ---------------------------------------------------------------------- root -- 6144 0 0 4 0 0 yds -- 4096 0 0 1 0 0 (2). chown yds /mnt/ubifs/1M [root@atest-guest linux_compile]# chown yds /mnt/ubifs/1M [root@atest-guest linux_compile]# ll -h /mnt/ubifs/ total 11M -rw-r--r--. 1 yds root 1.0M Sep 21 15:54 1M -rw-r--r--. 1 root root 2.0M Sep 21 15:54 2M -rw-r--r--. 1 root root 3.0M Sep 21 15:54 3M -rw-r--r--. 1 yds root 4.0M Sep 21 15:55 4M -rw-------. 1 root root 6.0K Sep 21 15:53 aquota.group -rw-------. 1 root root 7.0K Sep 21 15:53 aquota.user [root@atest-guest linux_compile]# repquota -u /mnt/ubifs/ *** Report for user quotas on device /dev/ubi0_0 Block grace time: 7days; Inode grace time: 7days Block limits File limits User used soft hard grace used soft hard grace ---------------------------------------------------------------------- root -- 5120 0 0 3 0 0 yds -- 5120 0 0 2 0 0 (3). quotacheck and check again. [root@atest-guest linux_compile]# quotaoff /mnt/ubifs && quotacheck -u /mnt/ubifs/ [root@atest-guest linux_compile]# ll -h /mnt/ubifs total 11M -rw-r--r--. 1 yds root 1.0M Sep 21 15:54 1M -rw-r--r--. 1 root root 2.0M Sep 21 15:54 2M -rw-r--r--. 1 root root 3.0M Sep 21 15:54 3M -rw-r--r--. 1 yds root 4.0M Sep 21 15:55 4M -rw-------. 1 root root 6.0K Sep 21 15:53 aquota.group -rw-------. 1 root root 7.0K Sep 21 16:00 aquota.user [root@atest-guest linux_compile]# repquota -u /mnt/ubifs/ *** Report for user quotas on device /dev/ubi0_0 Block grace time: 7days; Inode grace time: 7days Block limits File limits User used soft hard grace used soft hard grace ---------------------------------------------------------------------- root -- 5120 0 0 3 0 0 yds -- 5120 0 0 2 0 0 Yang > > Honza >