block: use lock bitops for the tag map.

The block queue tag map can use lock bitops.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 9 insertions, 11 deletions

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index d8616e6ebd92..a8a181072bf8 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -1057,18 +1057,16 @@ void blk_queue_end_tag(struct request_queue *q, struct request *rq)
 
         bqt->tag_index[tag] = NULL;
 
-        /*
-         * We use test_and_clear_bit's memory ordering properties here.
-         * The tag_map bit acts as a lock for tag_index[bit], so we need
-         * a barrer before clearing the bit (precisely: release semantics).
-         * Could use clear_bit_unlock when it is merged.
-         */
-        if (unlikely(!test_and_clear_bit(tag, bqt->tag_map))) {
+        if (unlikely(!test_bit(tag, bqt->tag_map))) {
                 printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n",
                        __FUNCTION__, tag);
                 return;
         }
-
+        /*
+         * The tag_map bit acts as a lock for tag_index[bit], so we need
+         * unlock memory barrier semantics.
+         */
+        clear_bit_unlock(tag, bqt->tag_map);
         bqt->busy--;
 }
 
@@ -1114,10 +1112,10 @@ int blk_queue_start_tag(struct request_queue *q, struct request *rq)
                 if (tag >= bqt->max_depth)
                         return 1;
 
-        } while (test_and_set_bit(tag, bqt->tag_map));
+        } while (test_and_set_bit_lock(tag, bqt->tag_map));
         /*
-         * We rely on test_and_set_bit providing lock memory ordering semantics
-         * (could use test_and_set_bit_lock when it is merged).
+         * We need lock ordering semantics given by test_and_set_bit_lock.
+         * See blk_queue_end_tag for details.
          */
 
         rq->cmd_flags |= REQ_QUEUED;