Re: Proposed changes to generic blk tag for use in SCSI (1/3)

[James Bottomley <James.Bottomley@steeleye.com>]

OK, this is the new patch with all the changes.  I didn't alter the IDE 
blk_queue_start_tag() to check for a REQ_CMD, since you said you would do that.

James

You can import this changeset into BK by piping this whole message to:
'| bk receive [path to repository]' or apply the patch as usual.

===================================================================


ChangeSet@1.490, 2002-06-11 12:33:05-04:00, jejb@mulgrave.(none)
  [BLK TCQ]
  
  remove blk_queue_tag_request() in favour of blk_queue_find_tag()
  Allow any request type into blk_queue_start_tag()

ChangeSet@1.489, 2002-06-11 10:34:17-04:00, jejb@mulgrave.(none)
  [BLK LAYER]
  
  add find tag function, adjust criteria for tagging commands.


 drivers/block/ll_rw_blk.c |   40 ++++++++++++++++++++++++++++++++++------
 drivers/ide/tcq.c         |    2 +-
 include/linux/blkdev.h    |    2 +-
 3 files changed, 36 insertions(+), 8 deletions(-)


diff -Nru a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
--- a/drivers/block/ll_rw_blk.c	Tue Jun 11 12:38:12 2002
+++ b/drivers/block/ll_rw_blk.c	Tue Jun 11 12:38:12 2002
@@ -297,6 +297,27 @@
 }
 
 /**
+ * blk_queue_find_tag - find a request by its tag and queue
+ *
+ * @q:	 The request queue for the device
+ * @tag: The tag of the request
+ *
+ * Notes:
+ *    Should be used when a device returns a tag and you want to match
+ *    it with a request.
+ *
+ *    no locks need be held.
+ **/
+struct request *blk_queue_find_tag(request_queue_t *q, int tag)
+{
+	struct blk_queue_tag *bqt = q->queue_tags;
+
+	if(unlikely(bqt == NULL || bqt->max_depth < tag))
+		return NULL;
+
+	return bqt->tag_index[tag];
+}
+/**
  * blk_queue_free_tags - release tag maintenance info
  * @q:  the request queue for the device
  *
@@ -429,10 +450,12 @@
  *  Description:
  *    This can either be used as a stand-alone helper, or possibly be
  *    assigned as the queue &prep_rq_fn (in which case &struct request
- *    automagically gets a tag assigned). Note that this function assumes
- *    that only REQ_CMD requests can be queued! The request will also be
- *    removed from the request queue, so it's the drivers responsibility to
- *    readd it if it should need to be restarted for some reason.
+ *    automagically gets a tag assigned). Note that this function
+ *    assumes that any type of request can be queued! if this is not
+ *    true for your device, you must check the request type before
+ *    calling this function.  The request will also be removed from
+ *    the request queue, so it's the drivers responsibility to readd
+ *    it if it should need to be restarted for some reason.
  *
  *  Notes:
  *   queue lock must be held.
@@ -443,8 +466,12 @@
 	unsigned long *map = bqt->tag_map;
 	int tag = 0;
 
-	if (unlikely(!(rq->flags & REQ_CMD)))
-		return 1;
+	if (unlikely((rq->flags & REQ_QUEUED))) {
+		printk(KERN_ERR 
+		       "request %p for device [02%x:02%x] already tagged %d",
+		       rq, major(rq->rq_dev), minor(rq->rq_dev), rq->tag);
+		BUG();
+	}
 
 	for (map = bqt->tag_map; *map == -1UL; map++) {
 		tag += BLK_TAGS_PER_LONG;
@@ -2027,6 +2054,7 @@
 
 EXPORT_SYMBOL(blk_queue_prep_rq);
 
+EXPORT_SYMBOL(blk_queue_find_tag);
 EXPORT_SYMBOL(blk_queue_init_tags);
 EXPORT_SYMBOL(blk_queue_free_tags);
 EXPORT_SYMBOL(blk_queue_start_tag);
diff -Nru a/drivers/ide/tcq.c b/drivers/ide/tcq.c
--- a/drivers/ide/tcq.c	Tue Jun 11 12:38:12 2002
+++ b/drivers/ide/tcq.c	Tue Jun 11 12:38:12 2002
@@ -282,7 +282,7 @@
 
 	TCQ_PRINTK("%s: stat %x, feat %x\n", __FUNCTION__, stat, feat);
 
-	rq = blk_queue_tag_request(&drive->queue, tag);
+	rq = blk_queue_find_tag(&drive->queue, tag);
 	if (!rq) {
 		printk(KERN_ERR"%s: missing request for tag %d\n", __FUNCTION__, tag);
 		return ide_stopped;
diff -Nru a/include/linux/blkdev.h b/include/linux/blkdev.h
--- a/include/linux/blkdev.h	Tue Jun 11 12:38:12 2002
+++ b/include/linux/blkdev.h	Tue Jun 11 12:38:12 2002
@@ -328,11 +328,11 @@
 /*
  * tag stuff
  */
-#define blk_queue_tag_request(q, tag)	((q)->queue_tags->tag_index[(tag)])
 #define blk_queue_tag_depth(q)		((q)->queue_tags->busy)
 #define blk_queue_tag_queue(q)		((q)->queue_tags->busy < (q)->queue_tags->
max_depth)
 #define blk_rq_tagged(rq)		((rq)->flags & REQ_QUEUED)
 extern int blk_queue_start_tag(request_queue_t *, struct request *);
+extern struct request *blk_queue_find_tag(request_queue_t *, int);
 extern void blk_queue_end_tag(request_queue_t *, struct request *);
 extern int blk_queue_init_tags(request_queue_t *, int);
 extern void blk_queue_free_tags(request_queue_t *);

===================================================================


This BitKeeper patch contains the following changesets:
1.489..1.490
## Wrapped with gzip_uu ##


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