From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH 1/5] [BLOCK] Add 'discard' request handling Date: Fri, 8 Aug 2008 13:47:32 +0200 Message-ID: <20080808114732.GS20055@kernel.dk> References: <1217957140.3454.800.camel@pmac.infradead.org> <1218014703.5111.35.camel@pmac.infradead.org> <20080807184155.GE20055@kernel.dk> <1218187995.12232.95.camel@pmac.infradead.org> <20080808103041.GM20055@kernel.dk> <1218192731.12232.110.camel@pmac.infradead.org> <20080808110934.GO20055@kernel.dk> <20080808111829.GP20055@kernel.dk> <1218194997.12232.124.camel@pmac.infradead.org> <20080808114409.GR20055@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andrew Morton , Ric Wheeler , linux-fsdevel@vger.kernel.org, gilad@codefidence.com To: David Woodhouse Return-path: Received: from brick.kernel.dk ([87.55.233.238]:14775 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755227AbYHHLre (ORCPT ); Fri, 8 Aug 2008 07:47:34 -0400 Content-Disposition: inline In-Reply-To: <20080808114409.GR20055@kernel.dk> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Fri, Aug 08 2008, Jens Axboe wrote: > Until we have overlap detection, I think we should make the discard > request a explicit barrier. Otherwise we could have problems with a > discard being passed by a write request and such. But that wreaks havoc with merging, since a barrier a) must be inserted at the back of the queue, and b) always has merging disabled -- Jens Axboe