Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758531Ab3GZKmV (ORCPT ); Fri, 26 Jul 2013 06:42:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:14483 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754686Ab3GZKmR (ORCPT ); Fri, 26 Jul 2013 06:42:17 -0400 Message-ID: <51F25277.6070704@redhat.com> Date: Fri, 26 Jul 2013 12:41:59 +0200 From: Jan Vesely User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 MIME-Version: 1.0 To: Jens Axboe , Alexander Viro , James Bottomley , linux-kernel@vger.kernel.org CC: Kent Overstreet , Rob Evers , Tomas Henzl , Nikola Pajkovsky , Kai Makisara , linux-scsi@vger.kernel.org, linux-fsdevel@vger.kernel.org, Don Howard , jano.vesely@gmail.com Subject: Re: [PATCH v4 0/2] block: Fix regression since 46081b166415acb66d4b3150ecefcd9460bb48a1 (was: Allow merging of tail pages into the last segment) References: <1373644343-6671-1-git-send-email-jvesely@redhat.com> In-Reply-To: <1373644343-6671-1-git-send-email-jvesely@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1310 Lines: 40 On 12/07/13 17:52, Jan Vesely wrote: > Hi > > These patches modify __bio_add_page to accept pages that extent the last bio > segment. some drivers craft their buffers and rely on this behavior (see > message in patch 2 for details) > > > jan > > v4: whitespace fixes to make checkpatch happy > > v3: Use code from __blk_recalc_rq_segments to decide whether the page is > mergeable, > > v2: modify a comment ping and a bit more info from patch 2/2: The original behavior was to refuse all pages after the maximum number of segments has been reached. However, some drivers (like st) craft their buffers to potentially require exactly max segments and multiple pages in the last segment. This patch modifies the check to allow pages that can be merged into the last segment. Fixes EBUSY failures when using large tape block size in high memory fragmentation condition. This regression was introduced by commit 46081b166415acb66d4b3150ecefcd9460bb48a1 st: Increase success probability in driver buffer allocation Jan -- Jan Vesely -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/