[SCSI] add scsi_build_sense_buffer helper function

This adds scsi_build_sense_buffer, a simple helper function to build
sense data in a buffer.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/scsi_error.c

@@ -1993,3 +1993,31 @@ int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,
 	}
 }
 EXPORT_SYMBOL(scsi_get_sense_info_fld);
+
+/**
+ * scsi_build_sense_buffer - build sense data in a buffer
+ * @desc:	Sense format (non zero == descriptor format,
+ * 		0 == fixed format)
+ * @buf:	Where to build sense data
+ * @key:	Sense key
+ * @asc:	Additional sense code
+ * @ascq:	Additional sense code qualifier
+ *
+ **/
+void scsi_build_sense_buffer(int desc, u8 *buf, u8 key, u8 asc, u8 ascq)
+{
+	if (desc) {
+		buf[0] = 0x72;	/* descriptor, current */
+		buf[1] = key;
+		buf[2] = asc;
+		buf[3] = ascq;
+		buf[7] = 0;
+	} else {
+		buf[0] = 0x70;	/* fixed, current */
+		buf[2] = key;
+		buf[7] = 0xa;
+		buf[12] = asc;
+		buf[13] = ascq;
+	}
+}
+EXPORT_SYMBOL(scsi_build_sense_buffer);

include/scsi/scsi_eh.h

@@ -58,6 +58,8 @@ extern const u8 * scsi_sense_desc_find(const u8 * sense_buffer, int sb_len,
 extern int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,
 				   u64 * info_out);
 
+extern void scsi_build_sense_buffer(int desc, u8 *buf, u8 key, u8 asc, u8 ascq);
+
 /*
  * Reset request from external source
  */