Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754836AbaJWJDf (ORCPT ); Thu, 23 Oct 2014 05:03:35 -0400 Received: from mail-lb0-f180.google.com ([209.85.217.180]:46949 "EHLO mail-lb0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752646AbaJWJDd (ORCPT ); Thu, 23 Oct 2014 05:03:33 -0400 MIME-Version: 1.0 In-Reply-To: References: <20141010074901.GA32028@sucs.org> <20141021041707.GA11691@sucs.org> Date: Thu, 23 Oct 2014 10:03:31 +0100 Message-ID: Subject: Re: [PATCH 0/3] scsi: Add Hyper-V logical block provisioning quirks From: Sitsofe Wheeler To: "Martin K. Petersen" Cc: "K. Y. Srinivasan" , Haiyang Zhang , Christoph Hellwig , Hannes Reinecke , "linux-scsi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "devel@linuxdriverproject.org" , "James E.J. Bottomley" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23 October 2014 02:50, Martin K. Petersen wrote: >>>>>> "Sitsofe" == Sitsofe Wheeler writes: > > Sitsofe> 2. On top of the above, when a disk is "small" (has less than > Sitsofe> 2^32 sectors which is typically < 2 TBytes in size) READ > Sitsofe> CAPACITY(16) won't be triggered. > > static int sd_try_rc16_first(struct scsi_device *sdp) > { > if (sdp->host->max_cmd_len < 16) > return 0; > if (sdp->try_rc_10_first) > return 0; > if (sdp->scsi_level > SCSI_SPC_2) > return 1; > if (scsi_device_protection(sdp)) > return 1; > return 0; > } Yes but since SCSI_SPC_2 was being advertised by the Hyper-V virtual disk (and presumably device protection isn't advertised either) this function was returning 0. That's why the patch in https://lkml.org/lkml/2014/10/10/49 added yet another quirk. If if SPC_3 were correctly advertised on Hyper-V virtual disks would TRY_VPD_PAGES still be needed to cope correctly with passthrough disks? What I didn't realise was that the TRY_VPD_PAGES quirk was purely to fix WRITE_SAME Hyper-V issues and not to address anything thin provisioning related. Having said that, why was the TRY_VPD_PAGES quirk back-ported 3.14 without any users - https://lkml.org/lkml/2014/9/15/733 ? -- Sitsofe | http://sucs.org/~sits/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/