Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/sparc-2.6

[sfrench/cifs-2.6.git] / block / ll_rw_blk.c

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 8c2caff87cc342819d53eb893f82269ea2205dec..ed39313c408534ee832e4ff61c428ba46c8b2c12 100644 (file)
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -1075,12 +1075,6 @@ void blk_queue_end_tag(struct request_queue *q, struct request *rq)
                 */
                return;
 
-       if (unlikely(!__test_and_clear_bit(tag, bqt->tag_map))) {
-               printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n",
-                      __FUNCTION__, tag);
-               return;
-       }
-
        list_del_init(&rq->queuelist);
        rq->cmd_flags &= ~REQ_QUEUED;
        rq->tag = -1;
@@ -1090,6 +1084,19 @@ void blk_queue_end_tag(struct request_queue *q, struct request *rq)
                       __FUNCTION__, tag);
 
        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))) {
+               printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n",
+                      __FUNCTION__, tag);
+               return;
+       }
+
        bqt->busy--;
 }
 
@@ -1136,6 +1143,10 @@ int blk_queue_start_tag(struct request_queue *q, struct request *rq)
                        return 1;
 
        } while (test_and_set_bit(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).
+        */
 
        rq->cmd_flags |= REQ_QUEUED;
        rq->tag = tag;
@@ -3047,6 +3058,10 @@ static inline void blk_partition_remap(struct bio *bio)
 
                bio->bi_sector += p->start_sect;
                bio->bi_bdev = bdev->bd_contains;
+
+               blk_add_trace_remap(bdev_get_queue(bio->bi_bdev), bio,
+                                   bdev->bd_dev, bio->bi_sector,
+                                   bio->bi_sector - p->start_sect);
        }
 }