From: Li Xi Subject: Re: [PATCH 0/4] quota: add project quota support Date: Fri, 1 Aug 2014 23:48:31 +0800 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Ext4 Developers List To: Jan Kara Return-path: Received: from mail-ig0-f182.google.com ([209.85.213.182]:52644 "EHLO mail-ig0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750738AbaHAPsc (ORCPT ); Fri, 1 Aug 2014 11:48:32 -0400 Received: by mail-ig0-f182.google.com with SMTP id c1so1795772igq.15 for ; Fri, 01 Aug 2014 08:48:31 -0700 (PDT) Sender: linux-ext4-owner@vger.kernel.org List-ID: 2014-08-01 23:28 GMT+08:00 Li Xi : > 2014-08-01 20:40 GMT+08:00 Jan Kara : >> >> 1) It should have been also posted to linux-fsdevel@vger.kernel.org, Al Viro >> , Christoph Hellwig because >> you are changing core VFS inode and infrastructure as well. For quota >> changes you should have also CCed me as a quota maintainer. > Sure. Thanks for reminding me. I will add these addresses next time. >> >> 2) I'm not convinced we actually want project ID in the core inode - so far >> only XFS has this. For everyone else it's just extra bloat so we could just >> put it in ext4_inode_info. Granted we'd need to somewhat change quota >> interface so that it sees all the ids (uid, gid, projid) but they are >> really needed in two places - dquot_initalize() and dquot_transfer() and >> creating variants of these functions that just take an array of ids and use >> them in ext4 is simple enough. > OK, agreed. After searching dquot_initalize() and dquot_transfer(), I found changing these two functions envolves too many file systems. Is there any good reason not to add kprojid_t field in inode structure? >> >> 3) I see no way how to get / set project ID from userspace. Did I miss >> something? > Yeah, you are right. I didn't push the interface patch. We implemeted > two kinds of interfaces. One is based on extended attribute interfaces which > simulate project ID as an extended attribute of the inode. The other implemented > a new ioctl command for ext4. Personally, I think ioctl is better. What is your > opinion? >> >> 4) The ext4 change is changing on-disk format. You definitely need a >> feature flag for that so that kernels that don't understand project quotas >> don't corrupt the filesystem. Also you need a support for this in >> e2fsprogs. > Sure. I will add feature flag for project quota of ext4. And there are > quite some > related tools need updates, including e2fsprogs and quota-tools. We will push > those patches as soon as they are ready. >> >> 5) You make the feature configurable both in quota code and ext4. I don't >> think the footprint of the feature warrants that. > Sure. Good point. > > Thank you for the advices, I will refresh the patches and send the mails to all > of the related addresses soon. > > Regards, > Li Xi