blk-mq: rename BLK_MQ_TAG_FAIL to BLK_MQ_NO_TAG

To prepare for wider use of this constant give it a more applicable name.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq-tag.c

@@ -111,7 +111,7 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
 	if (data->flags & BLK_MQ_REQ_RESERVED) {
 		if (unlikely(!tags->nr_reserved_tags)) {
 			WARN_ON_ONCE(1);
-			return BLK_MQ_TAG_FAIL;
+			return BLK_MQ_NO_TAG;
 		}
 		bt = &tags->breserved_tags;
 		tag_offset = 0;
@@ -125,7 +125,7 @@ unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)
 		goto found_tag;
 
 	if (data->flags & BLK_MQ_REQ_NOWAIT)
-		return BLK_MQ_TAG_FAIL;
+		return BLK_MQ_NO_TAG;
 
 	ws = bt_wait_ptr(bt, data->hctx);
 	do {

block/blk-mq-tag.h

@@ -44,9 +44,9 @@ static inline struct sbq_wait_state *bt_wait_ptr(struct sbitmap_queue *bt,
 }
 
 enum {
-	BLK_MQ_TAG_FAIL		= -1U,
+	BLK_MQ_NO_TAG		= -1U,
 	BLK_MQ_TAG_MIN		= 1,
-	BLK_MQ_TAG_MAX		= BLK_MQ_TAG_FAIL - 1,
+	BLK_MQ_TAG_MAX		= BLK_MQ_NO_TAG - 1,
 };
 
 extern bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *);

block/blk-mq.c

@@ -386,7 +386,7 @@ static struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data)
 	}
 
 	tag = blk_mq_get_tag(data);
-	if (tag == BLK_MQ_TAG_FAIL) {
+	if (tag == BLK_MQ_NO_TAG) {
 		if (clear_ctx_on_error)
 			data->ctx = NULL;
 		return NULL;