[PATCH] blk: use find_first_zero_bit() in blk_queue_start_tag()
blk_queue_start_tag() hand-coded searching for the first zero bit in the tag
map. Replace it with find_first_zero_bit(). With this patch,
blk_queue_star_tag() doesn't need to fill remains of tag map with 1, thus
allowing it to work properly with the next remove_real_max_depth patch.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Acked-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
index cd8cf30..808390c 100644
--- a/drivers/block/ll_rw_blk.c
+++ b/drivers/block/ll_rw_blk.c
@@ -968,8 +968,7 @@
int blk_queue_start_tag(request_queue_t *q, struct request *rq)
{
struct blk_queue_tag *bqt = q->queue_tags;
- unsigned long *map = bqt->tag_map;
- int tag = 0;
+ int tag;
if (unlikely((rq->flags & REQ_QUEUED))) {
printk(KERN_ERR
@@ -978,14 +977,10 @@
BUG();
}
- for (map = bqt->tag_map; *map == -1UL; map++) {
- tag += BLK_TAGS_PER_LONG;
+ tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth);
+ if (tag >= bqt->max_depth)
+ return 1;
- if (tag >= bqt->max_depth)
- return 1;
- }
-
- tag += ffz(*map);
__set_bit(tag, bqt->tag_map);
rq->flags |= REQ_QUEUED;