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Subject[PATCH 1/4] scsi: add scsi device flag to request VPD pages be used at SPC-2
Date
Under Hyper-V the disk devices support the trim extensions advertising them
via the appropriate VPD pages, it however reports itself as SPC-2 only.
The relevant pages were added in SPC-3 and later, so we do not even
attempt to see if they are present; the VPD page 0 lists which other
pages are present.

Add a scsi quirk bit to allow those devices to hint we can and should
try these VPD pages.

BugLink: http://bugs.launchpad.net/bugs/1223499
Signed-off-by: Andy Whitcroft <apw@canonical.com>
---
drivers/scsi/sd.c | 6 +++++-
include/scsi/scsi_device.h | 1 +
2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index b58e8f8..5a8a04d 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2667,8 +2667,12 @@ static int sd_try_extended_inquiry(struct scsi_device *sdp)
* Although VPD inquiries can go to SCSI-2 type devices,
* some USB ones crash on receiving them, and the pages
* we currently ask for are for SPC-3 and beyond
+ * Allow devices to request use of VPD inquiry at SPC-2
+ * as some devices implement these extensions (inc Hyper-V)
*/
- if (sdp->scsi_level > SCSI_SPC_2 && !sdp->skip_vpd_pages)
+ if ((sdp->scsi_level > SCSI_SPC_2 ||
+ (sdp->use_vpd_spc2 && sdp->scsi_level >= SCSI_SPC_2)) &&
+ !sdp->skip_vpd_pages)
return 1;
return 0;
}
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index d65fbec..9b7fdb6 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -149,6 +149,7 @@ struct scsi_device {
unsigned skip_ms_page_8:1; /* do not use MODE SENSE page 0x08 */
unsigned skip_ms_page_3f:1; /* do not use MODE SENSE page 0x3f */
unsigned skip_vpd_pages:1; /* do not read VPD pages */
+ unsigned use_vpd_spc2:1; /* do use VPD pages at SPC-2 */
unsigned use_192_bytes_for_3f:1; /* ask for 192 bytes from page 0x3f */
unsigned no_start_on_add:1; /* do not issue start on add */
unsigned allow_restart:1; /* issue START_UNIT in error handler */
--
1.8.1.2


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