> -----Original Message----- > From: James Bottomley [mailto:jbottom...@parallels.com] > Sent: Wednesday, July 9, 2014 3:27 PM > To: KY Srinivasan > Cc: linux-ker...@vger.kernel.org; m...@mkp.net; h...@infradead.org; > de...@linuxdriverproject.org; a...@canonical.com; sta...@vger.kernel.org; > linux-scsi@vger.kernel.org; oher...@suse.com; jasow...@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:jbottom...@parallels.com] > > > Sent: Wednesday, July 9, 2014 12:57 PM > > > To: KY Srinivasan > > > Cc: linux-ker...@vger.kernel.org; h...@infradead.org; > > > de...@linuxdriverproject.org; a...@canonical.com; > > > sta...@vger.kernel.org; linux-scsi@vger.kernel.org; > > > oher...@suse.com; jasow...@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:h...@infradead.org] > > > > > Sent: Wednesday, July 9, 2014 1:43 AM > > > > > To: KY Srinivasan > > > > > Cc: linux-ker...@vger.kernel.org; de...@linuxdriverproject.org; > > > > > oher...@suse.com; jbottom...@parallels.com; > jasow...@redhat.com; > > > > > a...@canonical.com; linux-scsi@vger.kernel.org; > > > > > sta...@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).
Ok; I am concerned about older kernels that do not have no_write_same flag. I suppose I can work directly with these Distros and give them a choice: either implement the no_write_same flag or filter the command in our driver. I will not include this patch when I resubmit this patch-set. Thanks, K. Y -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
