Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757447Ab3J1Tab (ORCPT ); Mon, 28 Oct 2013 15:30:31 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:39809 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756040Ab3J1Taa (ORCPT ); Mon, 28 Oct 2013 15:30:30 -0400 Date: Mon, 28 Oct 2013 12:30:24 -0700 From: Christoph Hellwig To: Jens Axboe Cc: Christoph Hellwig , Alexander Gordeev , Tejun Heo , Nicholas Bellinger , linux-kernel@vger.kernel.org Subject: Re: blk-mq flush fix Message-ID: <20131028193024.GA21108@infradead.org> References: <20131026114612.GA8576@infradead.org> <20131026153124.GA22227@infradead.org> <20131027222914.GG22549@kernel.dk> <20131028084821.GA31270@infradead.org> <526E90D7.1070604@kernel.dk> <20131028164641.GA1046@infradead.org> <526E97F4.3050104@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <526E97F4.3050104@kernel.dk> User-Agent: Mutt/1.5.21 (2010-09-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1207 Lines: 27 On Mon, Oct 28, 2013 at 10:59:32AM -0600, Jens Axboe wrote: > > The problem with it is that it will pass a tag number to the low level > > driver which it doesn't expect. In case the tags are used 1:1 as > > hardware tags that would lead to nasy bugs. > > > > At vefy least we'd need to mess with ->tag for this special request. > > Yes indeed. Actually the more I think about it, the better I like just > using the normal tagging infrastructure and punting to a reserved tag > for the flush. Just needs adding of the check whether it actually needs > it or not. That issue happens when using reserved tags as-is: e.g. the device supports 32 hardware tag, first reserved one is 33, something the hardware can't handle. So either way we'll have to copy over the tag from the original request. I don't think I can come up with something sane for that ASAP, so I'd suggest you actually do take my patch for now, and we'll sort something out less in a hurry. -- 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/