From dac56212e8127dbc0bff7be35c508bc280213309 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 17 Apr 2015 16:23:59 -0600 Subject: bio: skip atomic inc/dec of ->bi_cnt for most use cases Struct bio has a reference count that controls when it can be freed. Most uses cases is allocating the bio, which then returns with a single reference to it, doing IO, and then dropping that single reference. We can remove this atomic_dec_and_test() in the completion path, if nobody else is holding a reference to the bio. If someone does call bio_get() on the bio, then we flag the bio as now having valid count and that we must properly honor the reference count when it's being put. Tested-by: Robert Elliott Signed-off-by: Jens Axboe --- drivers/md/bcache/request.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/md') diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c index ab43fad..1616f66 100644 --- a/drivers/md/bcache/request.c +++ b/drivers/md/bcache/request.c @@ -619,7 +619,7 @@ static void do_bio_hook(struct search *s, struct bio *orig_bio) bio->bi_end_io = request_endio; bio->bi_private = &s->cl; - atomic_set(&bio->bi_cnt, 3); + bio_cnt_set(bio, 3); } static void search_free(struct closure *cl) -- cgit v1.1