This is a note to let you know that I've just added the patch titled
scsi: storvsc: Workaround for virtual DVD SCSI version
to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: scsi-storvsc-workaround-for-virtual-dvd-scsi-version.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From f1c635b439a5c01776fe3a25b1e2dc546ea82e6f Mon Sep 17 00:00:00 2001
From: Stephen Hemminger stephen@networkplumber.org Date: Tue, 7 Mar 2017 09:15:53 -0800 Subject: scsi: storvsc: Workaround for virtual DVD SCSI version
From: Stephen Hemminger stephen@networkplumber.org
commit f1c635b439a5c01776fe3a25b1e2dc546ea82e6f upstream.
Hyper-V host emulation of SCSI for virtual DVD device reports SCSI version 0 (UNKNOWN) but is still capable of supporting REPORTLUN.
Without this patch, a GEN2 Linux guest on Hyper-V will not boot 4.11 successfully with virtual DVD ROM device. What happens is that the SCSI scan process falls back to doing sequential probing by INQUIRY. But the storvsc driver has a previous workaround that masks/blocks all errors reports from INQUIRY (or MODE_SENSE) commands. This workaround causes the scan to then populate a full set of bogus LUN's on the target and then sends kernel spinning off into a death spiral doing block reads on the non-existent LUNs.
By setting the correct blacklist flags, the target with the DVD device is scanned with REPORTLUN and that works correctly.
Patch needs to go in current 4.11, it is safe but not necessary in older kernels.
Signed-off-by: Stephen Hemminger sthemmin@microsoft.com Reviewed-by: K. Y. Srinivasan kys@microsoft.com Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/scsi/storvsc_drv.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-)
--- a/drivers/scsi/storvsc_drv.c +++ b/drivers/scsi/storvsc_drv.c @@ -379,8 +379,6 @@ MODULE_PARM_DESC(vcpus_per_sub_channel, */ static int storvsc_timeout = 180;
-static int msft_blist_flags = BLIST_TRY_VPD_PAGES; -
static void storvsc_on_channel_callback(void *context);
@@ -1241,6 +1239,22 @@ static int storvsc_do_io(struct hv_devic return ret; }
+static int storvsc_device_alloc(struct scsi_device *sdevice) +{ + /* + * Set blist flag to permit the reading of the VPD pages even when + * the target may claim SPC-2 compliance. MSFT targets currently + * claim SPC-2 compliance while they implement post SPC-2 features. + * With this flag we can correctly handle WRITE_SAME_16 issues. + * + * Hypervisor reports SCSI_UNKNOWN type for DVD ROM device but + * still supports REPORT LUN. + */ + sdevice->sdev_bflags = BLIST_REPORTLUN2 | BLIST_TRY_VPD_PAGES; + + return 0; +} + static int storvsc_device_configure(struct scsi_device *sdevice) {
@@ -1256,14 +1270,6 @@ static int storvsc_device_configure(stru sdevice->no_write_same = 1;
/* - * Add blist flags to permit the reading of the VPD pages even when - * the target may claim SPC-2 compliance. MSFT targets currently - * claim SPC-2 compliance while they implement post SPC-2 features. - * With this patch we can correctly handle WRITE_SAME_16 issues. - */ - sdevice->sdev_bflags |= msft_blist_flags; - - /* * If the host is WIN8 or WIN8 R2, claim conformance to SPC-3 * if the device is a MSFT virtual device. If the host is * WIN10 or newer, allow write_same. @@ -1529,6 +1535,7 @@ static struct scsi_host_template scsi_dr .eh_host_reset_handler = storvsc_host_reset_handler, .proc_name = "storvsc_host", .eh_timed_out = storvsc_eh_timed_out, + .slave_alloc = storvsc_device_alloc, .slave_configure = storvsc_device_configure, .cmd_per_lun = 255, .this_id = -1,
Patches currently in stable-queue which might be from stephen@networkplumber.org are
queue-4.4/scsi-storvsc-workaround-for-virtual-dvd-scsi-version.patch