From: Mike Snitzer Subject: Re: Ext4 and xfs problems in dm-thin on allocation and discard Date: Mon, 2 Jul 2012 09:00:34 -0400 Message-ID: <20120702130034.GA785@redhat.com> References: <4FDF9EBE.2030809@shiftmail.org> <20120619015745.GJ25389@dastard> <4FE1BDF3.4080702@shiftmail.org> <20120620225327.GL30705@dastard> <20120621174742.GA27837@redhat.com> <4FF06480.6030109@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Dave Chinner , Spelic , device-mapper development , linux-ext4@vger.kernel.org, xfs@oss.sgi.com, axboe@kernel.dk, hch@infradead.org, "Martin K. Petersen" To: Paolo Bonzini Return-path: Received: from mx1.redhat.com ([209.132.183.28]:22142 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750815Ab2GBNA6 (ORCPT ); Mon, 2 Jul 2012 09:00:58 -0400 Content-Disposition: inline In-Reply-To: <4FF06480.6030109@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Sun, Jul 01 2012 at 10:53am -0400, Paolo Bonzini wrote: > Il 21/06/2012 19:47, Mike Snitzer ha scritto: > > Paolo Bonzini fixed blkdev_issue_discard to properly align some time > > ago; unfortunately the patches slipped through the cracks (cc'ing Paolo, > > Jens, and Christoph). > > > > Here are references to Paolo's patches: > > 0/2 https://lkml.org/lkml/2012/3/14/323 > > 1/2 https://lkml.org/lkml/2012/3/14/324 > > 2/2 https://lkml.org/lkml/2012/3/14/325 > > > > Patch 2/2 specifically addresses the case where: > > discard_max_bytes == discard_granularity > > > > Paolo, any chance you could resend to Jens (maybe with hch's comments on > > patch#2 accounted for)? Also, please add hch's Reviewed-by when > > reposting. > > Sure, I'll do it this week. I just need to retest. Great, thanks. (cc'ing mkp) One thing that seemed odd was your adjustment for discard_alignment (in patch 1/2). I need to better understand how discard_alignment (an offset despite the name not saying as much) relates to alignment_offset. Could just be that once a partition tool, or lvm, etc account for alignment_offset (which they do now) that discard_alignment is automagically accounted for as a side-effect? (I haven't actually seen discard_alignment != 0 in the wild) Mike