Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752583AbaFDQZ2 (ORCPT ); Wed, 4 Jun 2014 12:25:28 -0400 Received: from mail-pd0-f176.google.com ([209.85.192.176]:53151 "EHLO mail-pd0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753588AbaFDQZZ (ORCPT ); Wed, 4 Jun 2014 12:25:25 -0400 Message-ID: <538F4872.7050105@kernel.dk> Date: Wed, 04 Jun 2014 10:25:22 -0600 From: Jens Axboe User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Christoph Hellwig CC: Shaohua Li , linux-kernel@vger.kernel.org Subject: Re: [patch]blk-mq: blk_mq_tag_to_rq should handle flush request 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> <538F3DC4.4030104@kernel.dk> <538F3F82.5060805@kernel.dk> In-Reply-To: <538F3F82.5060805@kernel.dk> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/04/2014 09:47 AM, Jens Axboe wrote: > On 06/04/2014 09:39 AM, Jens Axboe wrote: >> On 06/04/2014 09:31 AM, 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; >> >> Ah yes, that'll work, the queue is always assigned. I'll make that change. > > Something like this in complete form. Compile tested only, I'll test it > on dev box. Probably doesn't matter too much, but I prefer to > potentially have the faster path (non-flush) just fall inline. Works for me, committed. -- Jens Axboe -- 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/