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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6EC3C001DF for ; Tue, 1 Aug 2023 11:11:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233682AbjHALLo (ORCPT ); Tue, 1 Aug 2023 07:11:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47698 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233697AbjHALLL (ORCPT ); Tue, 1 Aug 2023 07:11:11 -0400 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D7F0F1FC7; Tue, 1 Aug 2023 04:06:10 -0700 (PDT) Received: by verein.lst.de (Postfix, from userid 2407) id 49B2C68BFE; Tue, 1 Aug 2023 13:06:08 +0200 (CEST) Date: Tue, 1 Aug 2023 13:06:07 +0200 From: Christoph Hellwig To: Hannes Reinecke Cc: Christoph Hellwig , chengming.zhou@linux.dev, axboe@kernel.dk, ming.lei@redhat.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, zhouchengming@bytedance.com Subject: Re: [PATCH v2 1/4] blk-flush: flush_rq should inherit first_rq's cmd_flags Message-ID: <20230801110607.GB2781@lst.de> References: <20230725130102.3030032-1-chengming.zhou@linux.dev> <20230725130102.3030032-2-chengming.zhou@linux.dev> <20230731060957.GA30409@lst.de> <20230801110432.GA2781@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230801110432.GA2781@lst.de> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 01, 2023 at 01:04:32PM +0200, Christoph Hellwig wrote: > On Mon, Jul 31, 2023 at 06:28:01PM +0200, Hannes Reinecke wrote: > > The flush machinery is sending flushes before and/or after the original > > request (preflush/postflush). For blocked transports (ie during FC RSCN > > handling) the transport will error out commands depending on the FAILFAST > > setting. If FAILFAST is set the SCSI layer gets an STS_TRANSPORT error > > (causing the I/O to be retried), but STS_ERROR if not set (causing I/O to > > failed). > > > > So if the FAILFAST setting is _not_ aligned between flush_rq and the > > original we'll get an error on the flush rq and a retry on the original rq, > > causing the entire command to fail. > > > > I guess we need to align them. > > But you can't, because multiple pre/postflushes are coalesced into a > single outstanding flush request. They can and will not match quite > commonly. And if you mean the REQ_FAILFAST_TRANSPORT added by dm - this will never even see the flush state machine, as that is run in dm-mpath which then inserts the fully built flush request into the lower request queue. At least for request based multipath, bio could hit it.