block: remove unused ->busy part of the block queue tag map

It's not used for anything. On top of that, it's racy and can thus
trigger a faulty BUG_ON() in __blk_free_tags() on queue exit.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 2 insertions, 4 deletions

diff --git a/block/blk-tag.c b/block/blk-tag.c
index 32667beb03ee..ed5166fbc599 100644
--- a/block/blk-tag.c
+++ b/block/blk-tag.c
@@ -38,7 +38,8 @@ static int __blk_free_tags(struct blk_queue_tag *bqt)
 
         retval = atomic_dec_and_test(&bqt->refcnt);
         if (retval) {
-                BUG_ON(bqt->busy);
+                BUG_ON(find_first_bit(bqt->tag_map, bqt->max_depth) <
+                                                        bqt->max_depth);
 
                 kfree(bqt->tag_index);
                 bqt->tag_index = NULL;
@@ -147,7 +148,6 @@ static struct blk_queue_tag *__blk_queue_init_tags(struct request_queue *q,
         if (init_tag_map(q, tags, depth))
                 goto fail;
 
-        tags->busy = 0;
         atomic_set(&tags->refcnt, 1);
         return tags;
 fail:
@@ -313,7 +313,6 @@ void blk_queue_end_tag(struct request_queue *q, struct request *rq)
          * unlock memory barrier semantics.
          */
         clear_bit_unlock(tag, bqt->tag_map);
-        bqt->busy--;
 }
 EXPORT_SYMBOL(blk_queue_end_tag);
 
@@ -368,7 +367,6 @@ int blk_queue_start_tag(struct request_queue *q, struct request *rq)
         bqt->tag_index[tag] = rq;
         blkdev_dequeue_request(rq);
         list_add(&rq->queuelist, &q->tag_busy_list);
-        bqt->busy++;
         return 0;
 }
 EXPORT_SYMBOL(blk_queue_start_tag);