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authorDennis Zhou <dennis@kernel.org>2018-12-05 12:10:28 -0500
committerJens Axboe <axboe@kernel.dk>2018-12-07 22:26:36 -0700
commitbeea9da07d8a6228a7e4a31a83f9478d513bf03f (patch)
tree263661b03b835c4715fbeb97c2bdbd0331233001 /block/blk-throttle.c
parentb978962ad4f7f9c06e5aa07b2a9b22f6d600456c (diff)
blkcg: convert blkg_lookup_create() to find closest blkg
There are several scenarios where blkg_lookup_create() can fail such as the blkcg dying, request_queue is dying, or simply being OOM. Most handle this by simply falling back to the q->root_blkg and calling it a day. This patch implements the notion of closest blkg. During blkg_lookup_create(), if it fails to create, return the closest blkg found or the q->root_blkg. blkg_try_get_closest() is introduced and used during association so a bio is always attached to a blkg. Signed-off-by: Dennis Zhou <dennis@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-throttle.c')
-rw-r--r--block/blk-throttle.c4
1 files changed, 1 insertions, 3 deletions
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 8f0a104770ee..d648d6720f46 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -2118,9 +2118,7 @@ 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
- /* fallback to root_blkg if we fail to get a blkg ref */
- if (bio->bi_css && (bio_associate_blkg(bio, tg_to_blkg(tg)) == -ENODEV))
- bio_associate_blkg(bio, bio->bi_disk->queue->root_blkg);
+ bio_associate_blkg(bio, tg_to_blkg(tg));
bio_issue_init(&bio->bi_issue, bio_sectors(bio));
#endif
}