From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id 1BBBB7F47 for ; Fri, 15 Jan 2016 11:31:04 -0600 (CST) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay1.corp.sgi.com (Postfix) with ESMTP id EACAB8F8035 for ; Fri, 15 Jan 2016 09:31:03 -0800 (PST) Received: from sandeen.net (sandeen.net [63.231.237.45]) by cuda.sgi.com with ESMTP id j595OGlTQ9NTmFob for ; Fri, 15 Jan 2016 09:31:01 -0800 (PST) Subject: Re: [PATCH 0/4] quota: add new quotactl Q_XGETQUOTA2 References: <568FEA2C.6080708@redhat.com> <20160109072600.GA21636@infradead.org> <20160111132617.GD6262@quack.suse.cz> <5693D33A.5090307@sandeen.net> <20160111162807.GK6262@quack.suse.cz> <5696D27A.9070700@sandeen.net> <20160115093507.GA15950@quack.suse.cz> From: Eric Sandeen Message-ID: <56992CD4.6030408@sandeen.net> Date: Fri, 15 Jan 2016 11:31:00 -0600 MIME-Version: 1.0 In-Reply-To: <20160115093507.GA15950@quack.suse.cz> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Jan Kara Cc: Christoph Hellwig , fsdevel , xfs@oss.sgi.com, Eric Sandeen Hi Jan - On 1/15/16 3:35 AM, Jan Kara wrote: > On Wed 13-01-16 16:40:58, Eric Sandeen wrote: >> On 1/11/16 10:28 AM, Jan Kara wrote: ... >>> Actually, what I want from you is just an interface which is usable for VFS >>> quotas as well since I'd like to avoid adding GETQUOTA2 quotactl shortly >>> after XGETQUOTA2 :). >> >> Actually, that's exactly what I thought would *need* to happen ... we already >> have this weird 15-year-old split-brain quota interface, so if xfs and ext4 >> both need the same functionality, then we'd probably add both GETQUOTA2 and >> XGETQUOTA2. If we were doing this all from scratch, sure, but adding a new >> handles-both-quota-types interface when every other operation is already split >> between the two almost seems to make matters worse. > > Well, currently GETQUOTA and XGETQUOTA (and all the other quotactls) are > actually translated so they work regardless of the underlying filesystem. > So the only difference between XFS and VFS quotactls is in the formatting > of input/output structures. So from kernel POV it seems somewhat pointless > to add two calls doing the same thing and differing just in the formatting > of output - especially when we want the call to be extensible. > > I agree that having a unified call means having a new structure for passing > dquot info between kernel and userspace. So just for adding that one small > feature you want it seems like an overkill. But when thinking about new > extensible getquota quotactl it IMHO makes sense to unify the VFS/XFS split > brain. Thoughts? My first lazy/hacky thought is "how terrible would it be to overload the quotactl syscall return value with quota ID for Q_GETQUOTA2 calls?" For a purpose-built interface of "find the next ID" that wouldn't require any structure or interface changes... We could name it Q_GETNEXTQUOTA / Q_XGETNEXTQUOTA to make it explicit about the purpose, and document that return behavior. Done & done. ;) A new grand unified extensible quota call sounds like a great idea, I just hate to gate this work on designing a brand-new interface. -Eric _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs