From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C476BC43441 for ; Wed, 28 Nov 2018 07:37:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 81EF52086B for ; Wed, 28 Nov 2018 07:37:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="KiGsqSpG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 81EF52086B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-block-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727247AbeK1SiE (ORCPT ); Wed, 28 Nov 2018 13:38:04 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:43630 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727230AbeK1SiE (ORCPT ); Wed, 28 Nov 2018 13:38:04 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=wVHUGmwz57MgvKdCu4SZmJZ1Rwp/OvXIPNgTJwkHfxQ=; b=KiGsqSpGhPgbm2OU35gWVQ6QP 4/u1WT9QPhi5sk7EyNPD686RS049MDQtVVZA7TuoBUtWYtwSe/1E99se5I44MKEy3Hs64AU99+r4I npGNB9/pjmaoWha3js/tIYJKsP0cmkI83kKQI1XMJ06Fl3XaulH8pN0BXhs+9ojAKP2WHStZNHTG9 oqR8IErGKUahXKbsnTh9c85jPw/yhaODl4ov8ApVBd3+mTbnLLMDWFnWZsvcmxYw9Y44l8kJTpPq+ q/lfcxYQuN7g8qX5S7MVASFRV7fpYnnf+09vzyRi2cL5lSNlsyTTZ0nTKZ5czks1UqAW0+2tAwHuM hW2QHfv7A==; Received: from hch by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gRuPS-0003O4-S9; Wed, 28 Nov 2018 07:37:22 +0000 Date: Tue, 27 Nov 2018 23:37:22 -0800 From: Christoph Hellwig To: Dave Chinner Cc: Allison Henderson , linux-block@vger.kernel.org, linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, martin.petersen@oracle.com, shirley.ma@oracle.com, bob.liu@oracle.com Subject: Re: [RFC PATCH v1 0/7] Block/XFS: Support alternative mirror device retry Message-ID: <20181128073722.GB7084@infradead.org> References: <1543376991-5764-1-git-send-email-allison.henderson@oracle.com> <20181128053303.GL6311@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181128053303.GL6311@dastard> User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Wed, Nov 28, 2018 at 04:33:03PM +1100, Dave Chinner wrote: > One thing that is going to make this more complex at the XFS layer > is discontiguous buffers. They require multiple IOs (and therefore > bios) and so we are going to need to ensure that all the bios use > the same bi_rw_hint. Well, in case of raid 1 the load balancing code might actually map different bios to different initial legs. What we really need is to keep the 'index' or each bio. One good way to archive that is to just reuse the bio for the retry instead of allocating a new one.