[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 cd8cf302068c92a01aadef5a27b08cb309300da3..808390c742004dbc59adb75955de9f9327dec60d 100644 (file)
--- a/drivers/block/ll_rw_blk.c
+++ b/drivers/block/ll_rw_blk.c
@@ -968,8 +968,7 @@ EXPORT_SYMBOL(blk_queue_end_tag);
 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 @@ int blk_queue_start_tag(request_queue_t *q, struct request *rq)
                BUG();
        }
 
-       for (map = bqt->tag_map; *map == -1UL; map++) {
-               tag += BLK_TAGS_PER_LONG;
-
-               if (tag >= bqt->max_depth)
-                       return 1;
-       }
+       tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth);
+       if (tag >= bqt->max_depth)
+               return 1;
 
-       tag += ffz(*map);
        __set_bit(tag, bqt->tag_map);
 
        rq->flags |= REQ_QUEUED;