[SCSI] Make error printing more verbose

This patch enhances SCSI error printing by:

 - Making use of scsi_print_result() in the completion functions.

 - Having scmd_printk() output the disk name (when applicable).

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 9dd37e2..c86e6ce 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -5,6 +5,7 @@
 #include <linux/list.h>
 #include <linux/spinlock.h>
 #include <linux/workqueue.h>
+#include <linux/blkdev.h>
 #include <asm/atomic.h>
 
 struct request_queue;
@@ -154,8 +155,11 @@
 #define sdev_printk(prefix, sdev, fmt, a...)	\
 	dev_printk(prefix, &(sdev)->sdev_gendev, fmt, ##a)
 
-#define scmd_printk(prefix, scmd, fmt, a...)	\
-	dev_printk(prefix, &(scmd)->device->sdev_gendev, fmt, ##a)
+#define scmd_printk(prefix, scmd, fmt, a...)				\
+        (scmd)->request->rq_disk ?					\
+	sdev_printk(prefix, (scmd)->device, "[%s] " fmt,		\
+		    (scmd)->request->rq_disk->disk_name, ##a) :		\
+	sdev_printk(prefix, (scmd)->device, fmt, ##a)
 
 enum scsi_target_state {
 	STARGET_RUNNING = 1,