Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965135AbcDYVXa (ORCPT ); Mon, 25 Apr 2016 17:23:30 -0400 Received: from zimbra13.linbit.com ([212.69.166.240]:51555 "EHLO zimbra13.linbit.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964907AbcDYVX3 (ORCPT ); Mon, 25 Apr 2016 17:23:29 -0400 Date: Mon, 25 Apr 2016 23:23:25 +0200 From: Lars Ellenberg To: Philipp Reisner , Bart Van Assche , Jens Axboe , "linux-kernel@vger.kernel.org" , "drbd-dev@lists.linbit.com" Subject: Re: [PATCH 11/30] drbd: when receiving P_TRIM, zero-out partial unaligned chunks Message-ID: <20160425212325.GA20950@soda.linbit> Mail-Followup-To: Philipp Reisner , Bart Van Assche , Jens Axboe , "linux-kernel@vger.kernel.org" , "drbd-dev@lists.linbit.com" MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160425203217.GC25048@soda.linbit> <1461586077-11581-12-git-send-email-philipp.reisner@linbit.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1042 Lines: 31 On Mon, Apr 25, 2016 at 02:07:38PM +0200, Philipp Reisner wrote: > + max_discard_sectors = min(q->limits.max_discard_sectors, (1U << 22)); > + max_discard_sectors -= max_discard_sectors % granularity; ^^^^ there On Mon, Apr 25, 2016 at 10:32:17PM +0200, Lars Ellenberg wrote: > On Mon, Apr 25, 2016 at 09:37:28AM -0700, Bart Van Assche wrote: > > On 04/25/2016 05:13 AM, Philipp Reisner wrote: > > >+ while (nr_sectors >= granularity) { > > >+ nr = min_t(sector_t, nr_sectors, max_discard_sectors); > > >+ err |= blkdev_issue_discard(bdev, start, nr, GFP_NOIO, 0); > > >+ nr_sectors -= nr; > > >+ start += nr; > > >+ } > > > > Hello Phil, > > > > In blk_bio_discard_split() the following statement protects against > > block drivers for which max_discard_sectors is not a multiple of the > > discard granularity: > > > > max_discard_sectors -= max_discard_sectors % granularity; > > > > Do we need something similar in the above loop? > > Right. Did not realize that was "legal". Wait. We already have that. see above. Lars