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 AAAF2C001DF for ; Thu, 3 Aug 2023 15:36:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236773AbjHCPgG (ORCPT ); Thu, 3 Aug 2023 11:36:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59220 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236112AbjHCPgF (ORCPT ); Thu, 3 Aug 2023 11:36:05 -0400 Received: from out-126.mta0.migadu.com (out-126.mta0.migadu.com [91.218.175.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 24CE535B5 for ; Thu, 3 Aug 2023 08:36:02 -0700 (PDT) Message-ID: <405ef35e-5998-789f-8577-897b4cdf7e71@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1691076960; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=iNA9YhdOKBVSAzWkF33UHYzrNYmZHaHsWeYw1qfwm/k=; b=ejXhT62QbtY87EsgGl7l1TPJY2FsA7iXeQsd2omraTlTBqu7ck6bOEwaNJpo3GnSKx87IL cjW+P5s76dFQYOLrZkSq7iAbPzB9uMf4WSCZWoUzWtL2Mh0OlAPhesOvMGau47Vixo1VAy KXfdf47JFacpbHHwwISN+M2tWogod2A= Date: Thu, 3 Aug 2023 23:35:34 +0800 MIME-Version: 1.0 Subject: Re: [PATCH v2 1/4] blk-flush: flush_rq should inherit first_rq's cmd_flags Content-Language: en-US To: Christoph Hellwig , Hannes Reinecke Cc: axboe@kernel.dk, ming.lei@redhat.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, zhouchengming@bytedance.com References: <20230725130102.3030032-1-chengming.zhou@linux.dev> <20230725130102.3030032-2-chengming.zhou@linux.dev> <20230731060957.GA30409@lst.de> <20230801110432.GA2781@lst.de> <20230801110607.GB2781@lst.de> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Chengming Zhou In-Reply-To: <20230801110607.GB2781@lst.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2023/8/1 19:06, Christoph Hellwig wrote: > 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. Yes, multiple pre/postflushes are coalesced into a single flush request. So we can't figure out which request to use. >From the above explanation, can we just drop this inherit logic? It seems strange or wrong here. Thanks.