block: always attach cgroup info into bio

blkcg_bio_issue_check() already gets blkcg for a BIO.
bio_associate_blkcg() uses a percpu refcounter, so it's a very cheap
operation. There is no point we don't attach the cgroup info into bio at
blkcg_bio_issue_check. This also makes blktrace outputs correct cgroup
info.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 1 insertions, 6 deletions

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index a7285bf2831c..a6ebd2bdb4df 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -2104,14 +2104,9 @@ static inline void throtl_update_latency_buckets(struct throtl_data *td)
 static void blk_throtl_assoc_bio(struct throtl_grp *tg, struct bio *bio)
 {
 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
-        int ret;
-
-        ret = bio_associate_current(bio);
-        if (ret == 0 || ret == -EBUSY)
+        if (bio->bi_css)
                 bio->bi_cg_private = tg;
         blk_stat_set_issue(&bio->bi_issue_stat, bio_sectors(bio));
-#else
-        bio_associate_current(bio);
 #endif
 }