The Hyper-V host is queried to get the max transfer size that it supports, and this value is used to set max_sectors for the synthetic SCSI controller. However, this max transfer size may be too large for virtual Fibre Channel devices, which are limited to 512 Kbytes. If a larger transfer size is used with a vFC device, Hyper-V always returns an error, and storvsc logs a message like this where the SRB status and SCSI status are both zero:

hv_storvsc <GUID>: tag#197 cmd 0x8a status: scsi 0x0 srb 0x0 hv 0xc0000001

Add logic to limit the max transfer size to 512 Kbytes for vFC devices.

Fixes: 1d3e0980782f ("scsi: storvsc: Correct reporting of Hyper-V I/O size limits") Cc: stable@vger.kernel.org Signed-off-by: Michael Kelley mikelley@microsoft.com --- drivers/scsi/storvsc_drv.c | 4 ++++ 1 file changed, 4 insertions(+)

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index 7f12d93..f282321 100644 --- a/drivers/scsi/storvsc_drv.c +++ b/drivers/scsi/storvsc_drv.c @@ -366,6 +366,7 @@ enum storvsc_request_type { #define STORVSC_FC_MAX_LUNS_PER_TARGET 255 #define STORVSC_FC_MAX_TARGETS 128 #define STORVSC_FC_MAX_CHANNELS 8 +#define STORVSC_FC_MAX_XFER_SIZE ((u32)(512 * 1024))

#define STORVSC_IDE_MAX_LUNS_PER_TARGET 64 #define STORVSC_IDE_MAX_TARGETS 1 @@ -2006,6 +2007,9 @@ static int storvsc_probe(struct hv_device *device, * protecting it from any weird value. */ max_xfer_bytes = round_down(stor_device->max_transfer_bytes, HV_HYP_PAGE_SIZE); + if (is_fc) + max_xfer_bytes = min(max_xfer_bytes, STORVSC_FC_MAX_XFER_SIZE); + /* max_hw_sectors_kb */ host->max_sectors = max_xfer_bytes >> 9; /*