Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752320AbaFDQAY (ORCPT ); Wed, 4 Jun 2014 12:00:24 -0400 Received: from mail-vc0-f177.google.com ([209.85.220.177]:44636 "EHLO mail-vc0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751158AbaFDQAX (ORCPT ); Wed, 4 Jun 2014 12:00:23 -0400 MIME-Version: 1.0 In-Reply-To: <538F3FB5.2020102@kernel.dk> References: <20140509120733.GA27918@kernel.org> <20140509150018.GA26215@infradead.org> <20140510040023.GA13788@kernel.org> <5388912F.7010609@kernel.dk> <20140604111133.GA7826@infradead.org> <538F2A11.4060800@kernel.dk> <20140604142012.GA20056@infradead.org> <538F331F.60101@kernel.dk> <20140604145803.GA7826@infradead.org> <538F34FB.7050003@kernel.dk> <20140604153159.GA27096@infradead.org> <538F3FB5.2020102@kernel.dk> Date: Thu, 5 Jun 2014 00:00:22 +0800 Message-ID: Subject: Re: [patch]blk-mq: blk_mq_tag_to_rq should handle flush request From: Ming Lei To: Jens Axboe Cc: Christoph Hellwig , Shaohua Li , Linux Kernel Mailing List Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 4, 2014 at 11:48 PM, Jens Axboe wrote: > On 06/04/2014 09:43 AM, Ming Lei wrote: >> On Wed, Jun 4, 2014 at 11:31 PM, Christoph Hellwig wrote: >>> On Wed, Jun 04, 2014 at 09:02:19AM -0600, Jens Axboe wrote: >>>>> scsi_mq_find_tag only gets the scsi host, which may have multiple >>>>> queues. When called from scsi_find_tag we actually have a scsi device, >>>>> so that's not an issue, but when called from scsi_host_find_tag the >>>>> driver only provides the host. >>>> >>>> Only solution I see right now is to have the flush_rq in the shared >>>> tags, but that would potentially be a regression for multiple >>>> devices and heavy flush uses cases. I'll see if I can come up with >>>> something better, or maybe Shaohua has an idea. >>> >>> What about something like the following (untest, uncompiled, maybe >>> pseudo-code): >>> >>> struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag) >>> { >>> struct request *rq = tags->rqs[tag]; >>> >>> if ((rq->cmd_flags & REQ_FLUSH_SEQ) && rq->q->flush_rq->tag == tag) >>> return rq->q->flush_rq; >>> return rq; >>> } >> >> Looks we thought it together, :-) >> >> Also maybe the flush_rq->tag need to be cleared in flush_end_io(). > > It clears the command flag, so that should be enough. Only the flush_rq's command flag is cleared, and its parent request flag isn't cleared. Thanks, -- Ming Lei -- 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/