From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [PATCH 4/8] Drivers: scsi: storvsc: Filter WRITE_SAME_16 Date: Thu, 10 Jul 2014 22:12:46 +0000 Message-ID: <1405030365.2851.2.camel@jarvis.lan> References: <1404866789-26910-1-git-send-email-kys@microsoft.com> <1404866812-26950-1-git-send-email-kys@microsoft.com> <1404866812-26950-4-git-send-email-kys@microsoft.com> <20140709084300.GD6012@infradead.org> <1404935792.2184.5.camel@dabdike.int.hansenpartnership.com> <2f3ae589e6f149acbe4c5dd79f905971@BY2PR03MB299.namprd03.prod.outlook.com> <1404944843.2184.8.camel@dabdike.int.hansenpartnership.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Content-ID: <07553DE5B9811A41B231046AE692FFFB@sw.swsoft.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: driverdev-devel-bounces@linuxdriverproject.org To: "kys@microsoft.com" Cc: "linux-scsi@vger.kernel.org" , "jasowang@redhat.com" , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" , "ohering@suse.com" , "hch@infradead.org" , "mkp@mkp.net" , "apw@canonical.com" , "devel@linuxdriverproject.org" List-Id: linux-scsi@vger.kernel.org On Thu, 2014-07-10 at 21:02 +0000, KY Srinivasan wrote: > > > -----Original Message----- > > From: James Bottomley [mailto:jbottomley@parallels.com] > > Sent: Wednesday, July 9, 2014 3:27 PM > > To: KY Srinivasan > > Cc: linux-kernel@vger.kernel.org; mkp@mkp.net; hch@infradead.org; > > devel@linuxdriverproject.org; apw@canonical.com; stable@vger.kernel.org; > > linux-scsi@vger.kernel.org; ohering@suse.com; jasowang@redhat.com > > Subject: Re: [PATCH 4/8] Drivers: scsi: storvsc: Filter WRITE_SAME_16 > > > > On Wed, 2014-07-09 at 21:14 +0000, KY Srinivasan wrote: > > > > > > > -----Original Message----- > > > > From: James Bottomley [mailto:jbottomley@parallels.com] > > > > Sent: Wednesday, July 9, 2014 12:57 PM > > > > To: KY Srinivasan > > > > Cc: linux-kernel@vger.kernel.org; hch@infradead.org; > > > > devel@linuxdriverproject.org; apw@canonical.com; > > > > stable@vger.kernel.org; linux-scsi@vger.kernel.org; > > > > ohering@suse.com; jasowang@redhat.com > > > > Subject: Re: [PATCH 4/8] Drivers: scsi: storvsc: Filter > > > > WRITE_SAME_16 > > > > > > > > On Wed, 2014-07-09 at 19:52 +0000, KY Srinivasan wrote: > > > > > > > > > > > -----Original Message----- > > > > > > From: Christoph Hellwig [mailto:hch@infradead.org] > > > > > > Sent: Wednesday, July 9, 2014 1:43 AM > > > > > > To: KY Srinivasan > > > > > > Cc: linux-kernel@vger.kernel.org; devel@linuxdriverproject.org; > > > > > > ohering@suse.com; jbottomley@parallels.com; > > jasowang@redhat.com; > > > > > > apw@canonical.com; linux-scsi@vger.kernel.org; > > > > > > stable@vger.kernel.org > > > > > > Subject: Re: [PATCH 4/8] Drivers: scsi: storvsc: Filter > > > > > > WRITE_SAME_16 > > > > > > > > > > > > On Tue, Jul 08, 2014 at 05:46:48PM -0700, K. Y. Srinivasan wrote: > > > > > > > Host does not handle WRITE_SAME_16; filter this command out. > > > > > > > This patch is required to handle large devices (greater than 2 TB > > disks). > > > > > > > > > > > > Storvsc already sets the no_write_same flag, where is the > > > > > > command coming from? > > > > > > > > > > In spite of this flag, I see WRITE_SAME_16 being issued when I > > > > > format a device bigger than 2 TB; I tried both xfs and ext4. > > > > > Windows hosts currently do not handle unsupported commands > > > > > correctly - The information returned is not sufficient to effect recovery > > in the Linux guest. > > > > While this may be addressed in future hosts, this patch fixes the problem. > > > > > > > > What Christoph means is that this looks like a bug somewhere in SCSI > > itself. > > > > That means we need to find it and kill it, not add workarounds to > > > > every driver that sets no_write_same ... > > > > > > James, > > > > > > I will try to isolate this issue in the SCSI stack. If it is ok with > > > you guys, I would still want to filter WRITE_SAME_16 (as we currently > > > do WRITE_SAME) in our driver since this would address the problem for a > > large number of customers on our platform. > > > > If we fix it at source, why would there be any need to filter? That's the > > reason the no_write_same flag was introduced. If we can find and fix the > > bug, it can go back into the stable trees as a bug fix, hence nothing should > > ever emit write_same(10 or 16) and additional driver code is redundant (and > > counter productive, since if this ever breaks again you're our best canary). > > > > This looks like it might be the problem but Martin should confirm (I think the > > problem comes to us from the RC16 code which unconditionally sets WS16). > > > > James > > James, > > This patch works for me; are you planning on committing this patch. OK, if we go with this we can add your tested by. It's not going in until Martin takes a look because there may be a better way of doing this. James