From: Tejun Heo Subject: Re: [PATCH 3/3] block: reimplement FLUSH/FUA to support merge Date: Sun, 23 Jan 2011 11:31:33 +0100 Message-ID: <20110123103133.GC23121@htj.dyndns.org> References: <1295625598-15203-1-git-send-email-tj@kernel.org> <1295625598-15203-4-git-send-email-tj@kernel.org> <20110122004955.GA17792@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: axboe@kernel.dk, tytso@mit.edu, djwong@us.ibm.com, shli@kernel.org, neilb@suse.de, adilger.kernel@dilger.ca, jack@suse.cz, linux-kernel@vger.kernel.org, kmannth@us.ibm.com, cmm@us.ibm.com, linux-ext4@vger.kernel.org, rwheeler@redhat.com, hch@lst.de, josef@redhat.com To: Mike Snitzer Return-path: Received: from mail-fx0-f46.google.com ([209.85.161.46]:59609 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751211Ab1AWKbi (ORCPT ); Sun, 23 Jan 2011 05:31:38 -0500 Content-Disposition: inline In-Reply-To: <20110122004955.GA17792@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Fri, Jan 21, 2011 at 07:49:55PM -0500, Mike Snitzer wrote: > > + * If the device doesn't have writeback cache, FLUSH and FUA don't make any > > + * difference. The requests are either completed immediately if there's no > > + * data or executed as normal requests otherwise. > > For devices without a writeback cache, I'm not seeing where pure flushes > are completed immediately. But I do see where data is processed > directly in blk_insert_flush(). Yeah, it does. Pure flushes on a device w/o writeback cache, @policy is zero and blk_flush_complete_seq() will directly proceed to REQ_FSEQ_DONE. > > -struct request *blk_do_flush(struct request_queue *q, struct request *rq) > > +/** > > + * blk_abort_flush - @q is being aborted, abort flush requests > ^^^^^^^^^^^^^^^ > Small comment nit, s/blk_abort_flush/blk_abort_flushes/ Thanks. -- tejun