From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.136]:51467 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751239AbcEVNKJ (ORCPT ); Sun, 22 May 2016 09:10:09 -0400 Subject: Re: [f2fs-dev] [PATCH] f2fs: use bio count instead of F2FS_WRITEBACK page count To: Jaegeuk Kim , Chao Yu References: <1463532272-64148-1-git-send-email-jaegeuk@kernel.org> <1b8251a2-bc07-cfe2-21b0-c189cf74ca1f@huawei.com> <20160518013102.GA65174@jaegeuk.gateway> Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net From: Chao Yu Message-ID: <3a7e2bf6-fc6e-db09-9b3d-7cdd717d4560@kernel.org> Date: Sun, 22 May 2016 21:10:01 +0800 MIME-Version: 1.0 In-Reply-To: <20160518013102.GA65174@jaegeuk.gateway> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On 2016/5/18 9:31, Jaegeuk Kim wrote: > On Wed, May 18, 2016 at 09:17:00AM +0800, Chao Yu wrote: >> Hi Jaegeuk, >> >> On 2016/5/18 8:44, Jaegeuk Kim wrote: >>> This can reduce page counting overhead. >> >> We change to increase one reference for one bio, but block layer can split or >> merge bios by itself, and write_end will be called per bio, so the reference may >> be maintained incorrectly? > > Well, block layer will merge bios in a same request, and then finally call > end_io for each original bios, no? Sorry for the delay, I agree with you that end_io will be called for each bios in the merging case, and for the spliting case, IIUC, splited bio will chain to its parent bio, the real parent's end_io won't be called until both parent bio and bio have completed, so I think it's safe here. :) > So far I've seen no error in any test cases. I haven't seen any hungtask so far too. Thanks,