[SCSI mid-layer]

Add support for generic blk layer TCQ (needs blk_queue_find_tag
function)

drivers/scsi/hosts.h

@@ -562,6 +562,26 @@ extern int scsi_unregister_host(Scsi_Host_Template *);
 #define SD_EXTRA_DEVS CONFIG_SD_EXTRA_DEVS
 #define SR_EXTRA_DEVS CONFIG_SR_EXTRA_DEVS
 
+
+/**
+ * scsi_find_device - find a device given the host
+ * @channel:	SCSI channel (zero if only one channel)
+ * @pun:	SCSI target number (physical unit number)
+ * @lun:	SCSI Logical Unit Number
+ **/
+static inline Scsi_Device *scsi_find_device(struct Scsi_Host *host,
+                                            int channel, int pun, int lun) {
+        Scsi_Device *SDpnt;
+
+        for(SDpnt = host->host_queue;
+            SDpnt != NULL;
+            SDpnt = SDpnt->next)
+                if(SDpnt->channel == channel && SDpnt->id == pun
+                   && SDpnt->lun ==lun)
+                        break;
+        return SDpnt;
+}
+    
 #endif
 /*
  * Overrides for Emacs so that we follow Linus's tabbing style.

drivers/scsi/scsi.c

@@ -254,11 +254,20 @@ __setup("scsi_logging=", scsi_logging_setup);
  
 static void scsi_wait_done(Scsi_Cmnd * SCpnt)
 {
-	struct request *req;
+	struct request *req = SCpnt->request;
+        struct request_queue *q = &SCpnt->device->request_queue;
+        unsigned long flags;
 
-	req = SCpnt->request;
+        ASSERT_LOCK(q->queue_lock, 0);
 	req->rq_status = RQ_SCSI_DONE;	/* Busy, but indicate request done */
 
+        spin_lock_irqsave(q->queue_lock, flags);
+
+        if(blk_rq_tagged(req))
+                blk_queue_end_tag(q, req);
+
+        spin_unlock_irqrestore(q->queue_lock, flags);
+
 	if (req->waiting)
 		complete(req->waiting);
 }

drivers/scsi/scsi.h

@@ -560,6 +560,7 @@ struct scsi_device {
         atomic_t                device_active; /* commands checked out for device */
 	volatile unsigned short device_busy;	/* commands actually active on low-level */
 	Scsi_Cmnd *device_queue;	/* queue of SCSI Command structures */
+        Scsi_Cmnd *current_cmnd;	/* currently active command */
 
 	unsigned int id, lun, channel;
 
@@ -881,6 +882,8 @@ static inline void scsi_deactivate_tcq(Scsi_Device *SDpnt) {
 #define MSG_HEAD_TAG	0x21
 #define MSG_ORDERED_TAG	0x22
 
+#define SCSI_NO_TAG	(-1)    /* identify no tag in use */
+
 /**
  * scsi_populate_tag_msg - place a tag message in a buffer
  * @SCpnt:	pointer to the Scsi_Cmnd for the tag
@@ -907,6 +910,29 @@ static inline int scsi_populate_tag_msg(Scsi_Cmnd *SCpnt, char *msg) {
         return 2;
 }
 
+/**
+ * scsi_find_tag - find a tagged command by device
+ * @SDpnt:	pointer to the ScSI device
+ * @tag:	the tag number
+ *
+ * Notes:
+ *	Only works with tags allocated by the generic blk layer.
+ **/
+static inline Scsi_Cmnd *scsi_find_tag(Scsi_Device *SDpnt, int tag) {
+
+        struct request *req;
+
+        if(tag == SCSI_NO_TAG)
+                /* single command, look in space */
+                return SDpnt->current_cmnd;
+
+        req = blk_queue_find_tag(&SDpnt->request_queue, tag);
+
+        if(req == NULL)
+                return NULL;
+
+        return (Scsi_Cmnd *)req->special;
+}
 
 #endif
 

drivers/scsi/scsi_lib.c

@@ -76,7 +76,8 @@ static void __scsi_insert_special(request_queue_t *q, struct request *rq,
 	 * must not attempt merges on this) and that it acts as a soft
 	 * barrier
 	 */
-	rq->flags = REQ_SPECIAL | REQ_BARRIER;
+	rq->flags &= REQ_QUEUED;
+	rq->flags |= REQ_SPECIAL | REQ_BARRIER;
 
 	rq->special = data;
 
@@ -87,6 +88,9 @@ static void __scsi_insert_special(request_queue_t *q, struct request *rq,
 	 * device, or a host that is unable to accept a particular command.
 	 */
 	spin_lock_irqsave(q->queue_lock, flags);
+	/* If command is tagged, release the tag */
+	if(blk_rq_tagged(rq))
+		blk_queue_end_tag(q, rq);
 	_elv_add_request(q, rq, !at_head, 0);
 	q->request_fn(q);
 	spin_unlock_irqrestore(q->queue_lock, flags);
@@ -927,11 +931,13 @@ void scsi_request_fn(request_queue_t * q)
 		 * reason to search the list, because all of the commands
 		 * in this queue are for the same device.
 		 */
-		if(blk_queue_tagged(q))
-			blk_queue_start_tag(q, req);
-		else
+		if(!(blk_queue_tagged(q) && (blk_queue_start_tag(q, req) == 0)))
 			blkdev_dequeue_request(req);
 
+		/* note the overloading of req->special.  When the tag
+		 * is active it always means SCpnt.  If the tag goes
+		 * back for re-queueing, it may be reset */
+		req->special = SCpnt;
 		SCpnt->request = req;
 
 		/*