[PATCH] storvsc: add more logging for error and warning messages

[Long Li <longli@microsoft.com>]

Introduce a logging level for storvsc to log certain error/warning messages. Those messages are helpful in some environments, e.g. Microsoft Azure, for customer support and troubleshooting purposes.

Signed-off-by: Long Li <longli@microsoft.com>
---
 drivers/scsi/storvsc_drv.c | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 40c43ae..afa1647 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -164,6 +164,21 @@ static int sense_buffer_size = PRE_WIN8_STORVSC_SENSE_BUFFER_SIZE;
 */
 static int vmstor_proto_version;
 
+#define STORVSC_LOGGING_NONE	0
+#define STORVSC_LOGGING_ERROR	1
+#define STORVSC_LOGGING_WARN	2
+
+static int logging_level = STORVSC_LOGGING_ERROR;
+module_param(logging_level, int, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(logging_level,
+	"Logging level, 0 - None, 1 - Error (default), 2 - Warning.");
+
+static inline bool do_logging(int level)
+{
+	return (logging_level >= level) ? true : false;
+}
+
+
 struct vmscsi_win8_extension {
 	/*
 	 * The following were added in Windows 8
@@ -1183,7 +1198,7 @@ static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request)
 
 	scmnd->result = vm_srb->scsi_status;
 
-	if (scmnd->result) {
+	if (scmnd->result && do_logging(STORVSC_LOGGING_ERROR)) {
 		if (scsi_normalize_sense(scmnd->sense_buffer,
 				SCSI_SENSE_BUFFERSIZE, &sense_hdr))
 			scsi_print_sense_hdr(scmnd->device, "storvsc",
@@ -1239,12 +1254,25 @@ static void storvsc_on_io_completion(struct hv_device *device,
 	stor_pkt->vm_srb.sense_info_length =
 	vstor_packet->vm_srb.sense_info_length;
 
+	if (vstor_packet->vm_srb.scsi_status != 0 ||
+		vstor_packet->vm_srb.srb_status != SRB_STATUS_SUCCESS)
+		if (do_logging(STORVSC_LOGGING_WARN))
+			dev_warn(&device->device,
+				"cmd 0x%x scsi status 0x%x srb status 0x%x\n",
+				stor_pkt->vm_srb.cdb[0],
+				vstor_packet->vm_srb.scsi_status,
+				vstor_packet->vm_srb.srb_status);
 
 	if ((vstor_packet->vm_srb.scsi_status & 0xFF) == 0x02) {
 		/* CHECK_CONDITION */
 		if (vstor_packet->vm_srb.srb_status &
 			SRB_STATUS_AUTOSENSE_VALID) {
 			/* autosense data available */
+			if (do_logging(STORVSC_LOGGING_WARN))
+				dev_warn(&device->device,
+					"stor pkt %p autosense data valid - len %d\n",
+					request,
+					vstor_packet->vm_srb.sense_info_length);
 
 			memcpy(request->cmd->sense_buffer,
 			       vstor_packet->vm_srb.sense_data,
-- 
1.8.5.6