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authorDennis Zhou (Facebook) <dennisszhou@gmail.com>2018-09-11 14:41:29 -0400
committerJens Axboe <axboe@kernel.dk>2018-09-21 20:29:06 -0600
commita7b39b4e961c4e2b3ed837803a7441a65c90ce33 (patch)
tree7dda6dda4a341971504ccd16a44dbda27d57a0f8 /block/bio.c
parent07b05bcc3213ac9f8c28c9d835b4bf3d5798cc60 (diff)
blkcg: always associate a bio with a blkg
Previously, blkg's were only assigned as needed by blk-iolatency and blk-throttle. bio->css was also always being associated while blkg was being looked up and then thrown away in blkcg_bio_issue_check. This patch begins the cleanup of bio->css and bio->bi_blkg by always associating a blkg in blkcg_bio_issue_check. This tries to create the blkg, but if it is not possible, falls back to using the root_blkg of the request_queue. Therefore, a bio will always be associated with a blkg. The duplicate association logic is removed from blk-throttle and blk-iolatency. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/bio.c')
-rw-r--r--block/bio.c38
1 files changed, 38 insertions, 0 deletions
diff --git a/block/bio.c b/block/bio.c
index bfd41e8b53a8..748d7132f172 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -2029,6 +2029,41 @@ int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg)
}
/**
+ * bio_associate_create_blkg - associate a bio with a blkg from q
+ * @q: request_queue where bio is going
+ * @bio: target bio
+ *
+ * Associate @bio with the blkg found from the bio's css and the request_queue.
+ * If one is not found, bio_lookup_blkg creates the blkg.
+ */
+int bio_associate_create_blkg(struct request_queue *q, struct bio *bio)
+{
+ struct blkcg *blkcg;
+ struct blkcg_gq *blkg;
+ int ret = 0;
+
+ /* someone has already associated this bio with a blkg */
+ if (bio->bi_blkg)
+ return ret;
+
+ rcu_read_lock();
+
+ bio_associate_blkcg(bio, NULL);
+ blkcg = bio_blkcg(bio);
+
+ if (!blkcg->css.parent) {
+ ret = bio_associate_blkg(bio, q->root_blkg);
+ } else {
+ blkg = blkg_lookup_create(blkcg, q);
+
+ ret = bio_associate_blkg(bio, blkg);
+ }
+
+ rcu_read_unlock();
+ return ret;
+}
+
+/**
* bio_disassociate_task - undo bio_associate_current()
* @bio: target bio
*/
@@ -2057,6 +2092,9 @@ void bio_clone_blkcg_association(struct bio *dst, struct bio *src)
{
if (src->bi_css)
WARN_ON(bio_associate_blkcg(dst, src->bi_css));
+
+ if (src->bi_blkg)
+ bio_associate_blkg(dst, src->bi_blkg);
}
EXPORT_SYMBOL_GPL(bio_clone_blkcg_association);
#endif /* CONFIG_BLK_CGROUP */