[SCSI] fix up request buffer reference in various scsi drivers

Various scsi drivers use scsi_cmnd.buffer and scsi_cmnd.bufflen in their
queuecommand functions.  Those fields are internal storage for the
midlayer only and are used to restore the original payload after
request_buffer and request_bufflen have been overwritten for EH.  Using
the buffer and bufflen fields means they do very broken things in error
handling.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
diff --git a/drivers/scsi/megaraid.c b/drivers/scsi/megaraid.c
index 80b68a2..d245717 100644
--- a/drivers/scsi/megaraid.c
+++ b/drivers/scsi/megaraid.c
@@ -524,7 +524,7 @@
 	 * filter the internal and ioctl commands
 	 */
 	if((cmd->cmnd[0] == MEGA_INTERNAL_CMD)) {
-		return cmd->buffer;
+		return cmd->request_buffer;
 	}
 
 
@@ -4493,7 +4493,7 @@
 	scmd->device = sdev;
 
 	scmd->device->host = adapter->host;
-	scmd->buffer = (void *)scb;
+	scmd->request_buffer = (void *)scb;
 	scmd->cmnd[0] = MEGA_INTERNAL_CMD;
 
 	scb->state |= SCB_ACTIVE;