Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756128Ab3IMM6f (ORCPT ); Fri, 13 Sep 2013 08:58:35 -0400 Received: from mail-we0-f174.google.com ([74.125.82.174]:64800 "EHLO mail-we0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755987Ab3IMM6d (ORCPT ); Fri, 13 Sep 2013 08:58:33 -0400 From: Andy Whitcroft To: "James E.J. Bottomley" , "K. Y. Srinivasan" , Haiyang Zhang Cc: Andy Whitcroft , Ben Howard , linux-scsi@vger.kernel.org, devel@linuxdriverproject.org, linux-kernel@vger.kernel.org Subject: [PATCH 0/4] Hyper-V TRIM support Date: Fri, 13 Sep 2013 13:58:25 +0100 Message-Id: <1379077109-29606-1-git-send-email-apw@canonical.com> X-Mailer: git-send-email 1.8.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2247 Lines: 54 tl;dr -- enable TRIM support for Hyper-V emulated disks. The Hyper-V hypervisor can support TRIM for its devices, advertising this via the appropriate VPD pages. However the emulated disks only claim to be SPC-2 devices. According to the specs VPD pages (in general) did exist at SPC-2 but the specific pages we interogate for the TRIM support did not until SPC-3 therefore the kernel avoids reading the relevant pages for SPC-2 devices and prevents TRIM from being offered for these devices. Additionally at SPC-2 we prefer ReadCapacity10 over ReadCapacity16 and unless we use RC16 we will not identify the device as TRIM capable also preventing TRIM being offered. As the VPD page zero does list which pages are valid for each device, it could be argued that we could simply attempt to use these pages for all devices which claim to be SPC-2 and above. While this seems valid the code documents a number of devices which take badly to having even VPD page 0 interogated even when supposedly supported. Therefore it seems appropriate to add a scsi device flag to allow a device to request SPC-3 VPD pages be used when only at SPC-2. Similarly for the ReadCapacity selection it seems dangerous to invert the order for all SPC-2 devices. So it seems appropriate to add a scsi device flag to request we try RC16 before RC10 (mirroring the existing flag for the opposite). The following four patches add the two scsi device flags and select those flags for the Hyper-V emulated disks. Patches against v3.11. Comments? -apw Andy Whitcroft (4): scsi: add scsi device flag to request VPD pages be used at SPC-2 scsi: add scsi device flag to request READ CAPACITY (16) be preferred scsi: hyper-v storage -- mark as VPD capable at SPC-2 scsi: hyper-v storage -- mark as preferring READ CAPACITY (16) at SPC-2 drivers/scsi/sd.c | 8 +++++++- drivers/scsi/storvsc_drv.c | 2 ++ include/scsi/scsi_device.h | 2 ++ 3 files changed, 11 insertions(+), 1 deletion(-) -- 1.8.1.2 -- 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/