From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: [PATCH 2/2] sd: Try READ CAPACITY 16 first for SBC-2 devices Date: Thu, 12 Mar 2009 14:20:30 -0400 Message-ID: <1236882030-27964-3-git-send-email-willy@linux.intel.com> References: <1236882030-27964-1-git-send-email-willy@linux.intel.com> Return-path: Received: from ottawa-hs-206-191-39-47.d-ip.magma.ca ([206.191.39.47]:38384 "EHLO gonzo.int.wil.cx" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756345AbZCLSay (ORCPT ); Thu, 12 Mar 2009 14:30:54 -0400 In-Reply-To: <1236882030-27964-1-git-send-email-willy@linux.intel.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James.Bottomley@HansenPartnership.com Cc: linux-scsi@vger.kernel.org, Matthew Wilcox , Matthew Wilcox From: Matthew Wilcox New features are being added to the READ CAPACITY 16 results, so we want to issue it in preference to READ CAPACITY 10. Unfortunately, some devices misbehave when they see a READ CAPACITY 16, so we restrict this command to devices which claim conformance to SPC-3 (aka SBC-2), or claim they have features which are only reported in the READ CAPACITY 16 data. The READ CAPACITY 16 command is optional, even for SBC-2 devices, so we fall back to READ CAPACITY 10 if READ CAPACITY 16 fails. Signed-off-by: Matthew Wilcox Tested-by: Martin K. Petersen --- drivers/scsi/sd.c | 16 ++++++++++++++-- 1 files changed, 14 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 6cf0c25..b155488 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -1418,6 +1418,15 @@ static int read_capacity_10(struct scsi_disk *sdkp, struct scsi_device *sdp, return sector_size; } +static int sd_try_rc16_first(struct scsi_device *sdp) +{ + if (sdp->scsi_level > SCSI_SPC_2) + return 1; + if (scsi_device_protection(sdp)) + return 1; + return 0; +} + /* * read disk capacity */ @@ -1427,11 +1436,14 @@ sd_read_capacity(struct scsi_disk *sdkp, unsigned char *buffer) int sector_size; struct scsi_device *sdp = sdkp->device; - /* Force READ CAPACITY(16) when PROTECT=1 */ - if (scsi_device_protection(sdp)) { + if (sd_try_rc16_first(sdp)) { sector_size = read_capacity_16(sdkp, sdp, buffer); if (sector_size == -EOVERFLOW) goto got_data; + if (sector_size == -ENODEV) + return; + if (sector_size < 0) + sector_size = read_capacity_10(sdkp, sdp, buffer); if (sector_size < 0) return; } else { -- 1.6.1.3