scsi: storvsc: Handle PERSISTENT_RESERVE_IN truncation for Hyper-V vFC

The storvsc driver has become stricter in handling SRB status codes
returned by the Hyper-V host. When using Virtual Fibre Channel (vFC)
passthrough, the host may return SRB_STATUS_DATA_OVERRUN for
PERSISTENT_RESERVE_IN commands if the allocation length in the CDB does
not match the host's expected response size.

Currently, this status is treated as a fatal error, propagating
Host_status=0x07 [DID_ERROR] to the SCSI mid-layer. This causes
userspace storage utilities (such as sg_persist) to fail with transport
errors, even when the host has actually returned the requested
reservation data in the buffer.

Refactor the existing command-specific workarounds into a new helper
function, storvsc_host_mishandles_cmd(), and add PERSISTENT_RESERVE_IN
to the list of commands where SRB status errors should be suppressed for
vFC devices. This ensures that the SCSI mid-layer processes the returned
data buffer instead of terminating the command.

Signed-off-by: Li Tian <litian@redhat.com>
Reviewed-by: Long Li <longli@microsoft.com>
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Link: https://patch.msgid.link/20260406015344.12566-1-litian@redhat.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index ae1abab97835b207ed3eea3e8d3d48706689724e..6977ca8a06582ff069403ca0de9ba93844474846 100644 (file)
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1131,6 +1131,26 @@ static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request,
                kfree(payload);
 }
 
+/*
+ * The current SCSI handling on the host side does not correctly handle:
+ * INQUIRY with page code 0x80, MODE_SENSE / MODE_SENSE_10 with cmd[2] == 0x1c,
+ * and (for FC) MAINTENANCE_IN / PERSISTENT_RESERVE_IN passthrough.
+ */
+static bool storvsc_host_mishandles_cmd(u8 opcode, struct hv_device *device)
+{
+       switch (opcode) {
+       case INQUIRY:
+       case MODE_SENSE:
+       case MODE_SENSE_10:
+               return true;
+       case MAINTENANCE_IN:
+       case PERSISTENT_RESERVE_IN:
+               return hv_dev_is_fc(device);
+       default:
+               return false;
+       }
+}
+
 static void storvsc_on_io_completion(struct storvsc_device *stor_device,
                                  struct vstor_packet *vstor_packet,
                                  struct storvsc_cmd_request *request)
@@ -1141,22 +1161,12 @@ static void storvsc_on_io_completion(struct storvsc_device *stor_device,
        stor_pkt = &request->vstor_packet;
 
        /*
-        * The current SCSI handling on the host side does
-        * not correctly handle:
-        * INQUIRY command with page code parameter set to 0x80
-        * MODE_SENSE and MODE_SENSE_10 command with cmd[2] == 0x1c
-        * MAINTENANCE_IN is not supported by HyperV FC passthrough
-        *
         * Setup srb and scsi status so this won't be fatal.
         * We do this so we can distinguish truly fatal failues
         * (srb status == 0x4) and off-line the device in that case.
         */
 
-       if ((stor_pkt->vm_srb.cdb[0] == INQUIRY) ||
-          (stor_pkt->vm_srb.cdb[0] == MODE_SENSE) ||
-          (stor_pkt->vm_srb.cdb[0] == MODE_SENSE_10) ||
-          (stor_pkt->vm_srb.cdb[0] == MAINTENANCE_IN &&
-          hv_dev_is_fc(device))) {
+       if (storvsc_host_mishandles_cmd(stor_pkt->vm_srb.cdb[0], device)) {
                vstor_packet->vm_srb.scsi_status = 0;
                vstor_packet->vm_srb.srb_status = SRB_STATUS_SUCCESS;
        }