From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755193Ab0F1ISw (ORCPT ); Mon, 28 Jun 2010 04:18:52 -0400 Received: from 0122700014.0.fullrate.dk ([95.166.99.235]:53101 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753837Ab0F1ISu (ORCPT ); Mon, 28 Jun 2010 04:18:50 -0400 Message-ID: <4C285AE8.9090702@kernel.dk> Date: Mon, 28 Jun 2010 10:18:48 +0200 From: Jens Axboe MIME-Version: 1.0 To: FUJITA Tomonori CC: hch@lst.de, snitzer@redhat.com, dm-devel@redhat.com, James.Bottomley@suse.de, linux-kernel@vger.kernel.org, martin.petersen@oracle.com, akpm@linux-foundation.org, linux-scsi@vger.kernel.org Subject: Re: [PATCH 1/2] block: fix leaks associated with discard request payload References: <20100627110712.GA14511@lst.de> <20100627212952D.fujita.tomonori@lab.ntt.co.jp> <20100628075738.GA26606@lst.de> <20100628171218Q.fujita.tomonori@lab.ntt.co.jp> In-Reply-To: <20100628171218Q.fujita.tomonori@lab.ntt.co.jp> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2010-06-28 10:14, FUJITA Tomonori wrote: > On Mon, 28 Jun 2010 09:57:38 +0200 > Christoph Hellwig wrote: > >> On Sun, Jun 27, 2010 at 09:32:07PM +0900, FUJITA Tomonori wrote: >>> On Sun, 27 Jun 2010 13:07:12 +0200 >>> Christoph Hellwig wrote: >>> >>>>> How about this? >>>> >>>> As I tried to explain before this utterly confuses the I/O completion >>>> path. With the patch applied even a simple mkfs.xfs that issues discard >>>> just hangs. >>> >>> Wired. I just tried mkfs.xfs against scsi_debug with my block patches >>> (I saw one discard command). Seemed that it worked fine. >> >> I've tracked it down to the call to scsi_requeue_command in scsi_end_request. >> When the command is marked BLOCK_PC we'll just get it back as such in >> ->prep_fn next time, but now it's reverting to the previous state. > > If scsi_end_request() calls scsi_requeue_command(), the command has a > left over (i.e. hasn't finished all the data), right? You hit such > condition with discard commands? > > BLOCK_PC requests don't hit this case since blk_end_request() always > return false for PC. You can get requeues on the ->queuecommand() path as well, for a variety of reasons, and that would be what Christoph is hitting. -- Jens Axboe