From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kent Overstreet Subject: Re: [PATCH v5 01/11] block: make generic_make_request handle arbitrarily sized bios Date: Fri, 7 Aug 2015 17:30:57 -0700 Message-ID: <20150808003057.GA1811@kmo-pixel> References: <20150731192337.GA8907@redhat.com> <20150731213831.GA16464@redhat.com> <1438412290.26596.14.camel@hasee> <20150801163356.GA21478@redhat.com> <1438581502.26596.24.camel@hasee> <20150804113626.GA12682@lst.de> <1438754604.29731.31.camel@hasee> <20150807073001.GA17485@lst.de> <1438990806.24452.8.camel@ssi> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1438990806.24452.8.camel@ssi> Sender: linux-kernel-owner@vger.kernel.org To: Ming Lin Cc: Christoph Hellwig , Mike Snitzer , lkml , Jens Axboe , Dongsu Park , Christoph Hellwig , Al Viro , Ming Lei , Neil Brown , Alasdair Kergon , dm-devel@redhat.com, Lars Ellenberg , drbd-user@lists.linbit.com, Jiri Kosina , Geoff Levand , Jim Paris , Philip Kelleher , Minchan Kim , Nitin Gupta , Oleg Drokin , Andreas Dilger , Ming Lin List-Id: dm-devel.ids On Fri, Aug 07, 2015 at 04:40:06PM -0700, Ming Lin wrote: > > On Fri, 2015-08-07 at 09:30 +0200, Christoph Hellwig wrote: > > I'm for solution 3: > > > > - keep blk_bio_{discard,write_same}_split, but ensure we never built > > a > 4GB bio in blkdev_issue_{discard,write_same}. > > This has problem as I mentioned in solution 1. > We need to also make sure max discard size is of proper granularity. > See below example. > > 4G: 8388608 sectors > UINT_MAX: 8388607 sectors > > dm-thinp block size = default discard granularity = 128 sectors > > blkdev_issue_discard(sector=0, nr_sectors=8388608) > > 1. Only ensure bi_size not overflow > > It doesn't work. > > [start_sector, end_sector] > [0, 8388607] > [0, 8388606], then dm-thinp splits it to 2 bios > [0, 8388479] > [8388480, 8388606] ---> this has problem in process_discard_bio(), > because the discard size(7 sectors) covers less than a block(128 sectors) > [8388607, 8388607] ---> same problem > > 2. Ensure bi_size not overflow and max discard size is of proper granularity Ideally we'd get upper layers out of the business of knowing about the queue limits at all - that was the point of the patch series, after all. Instead of using UINT_MAX, would it work to just make the max 1 << 31 sectors? From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from zimbra13.linbit.com (zimbra.linbit.com [212.69.161.123]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by mail09.linbit.com (LINBIT Mail Daemon) with ESMTPS id F12DB105570E for ; Fri, 11 Sep 2015 15:20:06 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by zimbra13.linbit.com (Postfix) with ESMTP id AD9C62BEE36 for ; Fri, 11 Sep 2015 15:20:06 +0200 (CEST) Received: from zimbra13.linbit.com ([127.0.0.1]) by localhost (zimbra13.linbit.com [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id pYoshgZ8EvHJ for ; Fri, 11 Sep 2015 15:20:06 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by zimbra13.linbit.com (Postfix) with ESMTP id 805BE2BEE3E for ; Fri, 11 Sep 2015 15:20:06 +0200 (CEST) Received: from zimbra13.linbit.com ([127.0.0.1]) by localhost (zimbra13.linbit.com [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id 4rTKFogp_EtA for ; Fri, 11 Sep 2015 15:20:05 +0200 (CEST) Received: from soda.linbit (tuerlsteher.linbit.com [86.59.100.100]) by zimbra13.linbit.com (Postfix) with ESMTPS id 19F8F2BEE36 for ; Fri, 11 Sep 2015 15:20:03 +0200 (CEST) Resent-Message-ID: <20150911132003.GR3436@soda.linbit> From: Kent Overstreet To: Ming Lin Message-ID: <20150808003057.GA1811@kmo-pixel> References: <20150731192337.GA8907@redhat.com> <20150731213831.GA16464@redhat.com> <1438412290.26596.14.camel@hasee> <20150801163356.GA21478@redhat.com> <1438581502.26596.24.camel@hasee> <20150804113626.GA12682@lst.de> <1438754604.29731.31.camel@hasee> <20150807073001.GA17485@lst.de> <1438990806.24452.8.camel@ssi> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1438990806.24452.8.camel@ssi> Cc: Mike Snitzer , Neil Brown , Ming Lei , dm-devel@redhat.com, Christoph Hellwig , Alasdair Kergon , Lars Ellenberg , Philip Kelleher , Christoph Hellwig , Nitin Gupta , Ming Lin , Oleg Drokin , Al Viro , Jens Axboe , Andreas Dilger , Geoff Levand , Jiri Kosina , lkml , Jim Paris , Minchan Kim , Dongsu Park , drbd-user@lists.linbit.com Subject: Re: [Drbd-dev] [PATCH v5 01/11] block: make generic_make_request handle arbitrarily sized bios List-Id: "*Coordination* of development, patches, contributions -- *Questions* \(even to developers\) go to drbd-user, please." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Date: Fri, 11 Sep 2015 13:20:07 -0000 On Fri, Aug 07, 2015 at 04:40:06PM -0700, Ming Lin wrote: > > On Fri, 2015-08-07 at 09:30 +0200, Christoph Hellwig wrote: > > I'm for solution 3: > > > > - keep blk_bio_{discard,write_same}_split, but ensure we never built > > a > 4GB bio in blkdev_issue_{discard,write_same}. > > This has problem as I mentioned in solution 1. > We need to also make sure max discard size is of proper granularity. > See below example. > > 4G: 8388608 sectors > UINT_MAX: 8388607 sectors > > dm-thinp block size = default discard granularity = 128 sectors > > blkdev_issue_discard(sector=0, nr_sectors=8388608) > > 1. Only ensure bi_size not overflow > > It doesn't work. > > [start_sector, end_sector] > [0, 8388607] > [0, 8388606], then dm-thinp splits it to 2 bios > [0, 8388479] > [8388480, 8388606] ---> this has problem in process_discard_bio(), > because the discard size(7 sectors) covers less than a block(128 sectors) > [8388607, 8388607] ---> same problem > > 2. Ensure bi_size not overflow and max discard size is of proper granularity Ideally we'd get upper layers out of the business of knowing about the queue limits at all - that was the point of the patch series, after all. Instead of using UINT_MAX, would it work to just make the max 1 << 31 sectors?