From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Sandeen Subject: Re: [PATCH] scsi_debug: add LBPRZ support Date: Wed, 07 Mar 2012 19:18:35 -0600 Message-ID: <4F5808EB.9000909@redhat.com> References: <4F57C061.9020807@redhat.com> <4F58049C.5010505@interlog.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:3495 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751542Ab2CHBSj (ORCPT ); Wed, 7 Mar 2012 20:18:39 -0500 In-Reply-To: <4F58049C.5010505@interlog.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: dgilbert@interlog.com Cc: "linux-scsi@vger.kernel.org" , mkp@mkp.net, =?windows-1252?Q?Luk=E1=9A_Czerner?= On 3/7/12 7:00 PM, Douglas Gilbert wrote: > On 12-03-07 03:09 PM, Eric Sandeen wrote: >> Add LBPRZ support to scsi_debug; i.e. return zero for >> unmapped blocks. >> >> Rather than checking for unmapped blocks at >> read time, this just zeroes them on the backing store >> at unmap time so it behaves the same way. >> >> This also adds a module parameter to disable it, since >> some SSDs have this behavior. >> >> unmap_zeroes, "unmapped blocks return 0 on read (def=1)" >> >> Signed-off-by: Eric Sandeen >> --- >> >> Note: This was sent long ago as "TPRZ" support, but lost, I guess. >> >> Note2: dgilbert preferred "zeros" to "zeroes" at the time, >> but since we have "discard_zeroes_data" in sysfs it seems like >> we should be consistent with the kernel precedent, rather than >> the spec spelling. > > Eric, > I checked the latest drafts of SPC-4 and SBC-3 and they > contain both "zeros" and "zeroes". Take your pick! While we're talking about names, looking at other scsi_debug_* flags should it be lbprz / scsi_debug_lbprz / DEF_LBPRZ instead of unmap_zeroes / scsi_debug_unmap_zeroes / DEF_UNMAP_ZEROES? > More seriously the LBPRZ flag now appears in the Logical > Block Provisioning VPD page and the READ CAPACITY (16) > response. Your patch sets the latter, could you add the > LBPRZ flag setting in the inquiry_evpd_b2() function as > well. Perhaps: > if (scsi_debug_unmap_zeroes) > arr[1] |= 1 << 2; ok; I'm no scsi guy, just a pattern-following monkey but I'll change that if you say it's right. :) > And if your are editing that function in the comment introducing > that function: > s/Thin/Logical block/ > to reflect the renaming done by t10.org . ok. > Ah, and inquiry_evpd_b2() should return 4 (not 8). Is that at all related to this change or some other random bug? Should that return be unconditional? Should that be a separate patch? By someone who knows what it means? :) > Otherwise it looks good. Thanks, -Eric > Doug Gilbert >