From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>, Tejun Heo <tj@kernel.org>
Cc: Dennis Zhou <dennis@kernel.org>, Li Zefan <lizefan@huawei.com>,
Johannes Weiner <hannes@cmpxchg.org>,
dm-devel@redhat.com, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
linux-mm@kvack.org
Subject: [PATCH 09/14] block: move the initial blkg lookup into blkg_tryget_closest
Date: Sat, 27 Jun 2020 09:31:54 +0200 [thread overview]
Message-ID: <20200627073159.2447325-10-hch@lst.de> (raw)
In-Reply-To: <20200627073159.2447325-1-hch@lst.de>
By moving the initial blkg lookup into blkg_tryget_closest we get
a nicely self contained routines that does all the RCU locking.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
block/blk-cgroup.c | 33 ++++++++++++++-------------------
1 file changed, 14 insertions(+), 19 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 0912820d4f8194..d21ec2acd716e7 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1716,19 +1716,20 @@ void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta)
/**
* blkg_tryget_closest - try and get a blkg ref on the closet blkg
- * @blkg: blkg to get
+ * @bio: target bio
+ * @css: target css
*
- * This needs to be called rcu protected. As the failure mode here is to walk
- * up the blkg tree, this ensure that the blkg->parent pointers are always
- * valid. This returns the blkg that it ended up taking a reference on or %NULL
- * if no reference was taken.
+ * As the failure mode here is to walk up the blkg tree, this ensure that the
+ * blkg->parent pointers are always valid. This returns the blkg that it ended
+ * up taking a reference on or %NULL if no reference was taken.
*/
-static inline struct blkcg_gq *blkg_tryget_closest(struct blkcg_gq *blkg)
+static inline struct blkcg_gq *blkg_tryget_closest(struct bio *bio,
+ struct cgroup_subsys_state *css)
{
- struct blkcg_gq *ret_blkg = NULL;
-
- WARN_ON_ONCE(!rcu_read_lock_held());
+ struct blkcg_gq *blkg, *ret_blkg = NULL;
+ rcu_read_lock();
+ blkg = blkg_lookup_create(css_to_blkcg(css), bio->bi_disk->queue);
while (blkg) {
if (blkg_tryget(blkg)) {
ret_blkg = blkg;
@@ -1736,6 +1737,7 @@ static inline struct blkcg_gq *blkg_tryget_closest(struct blkcg_gq *blkg)
}
blkg = blkg->parent;
}
+ rcu_read_unlock();
return ret_blkg;
}
@@ -1757,21 +1759,14 @@ static inline struct blkcg_gq *blkg_tryget_closest(struct blkcg_gq *blkg)
void bio_associate_blkg_from_css(struct bio *bio,
struct cgroup_subsys_state *css)
{
- struct request_queue *q = bio->bi_disk->queue;
-
if (bio->bi_blkg)
blkg_put(bio->bi_blkg);
if (css && css->parent) {
- struct blkcg_gq *blkg;
-
- rcu_read_lock();
- blkg = blkg_lookup_create(css_to_blkcg(css), q);
- bio->bi_blkg = blkg_tryget_closest(blkg);
- rcu_read_unlock();
+ bio->bi_blkg = blkg_tryget_closest(bio, css);
} else {
- blkg_get(q->root_blkg);
- bio->bi_blkg = q->root_blkg;
+ blkg_get(bio->bi_disk->queue->root_blkg);
+ bio->bi_blkg = bio->bi_disk->queue->root_blkg;
}
}
EXPORT_SYMBOL_GPL(bio_associate_blkg_from_css);
--
2.26.2
next prev parent reply other threads:[~2020-06-27 7:31 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-27 7:31 drive-by blk-cgroup cleanups Christoph Hellwig
2020-06-27 7:31 ` [PATCH 01/14] dm: use bio_uninit instead of bio_disassociate_blkg Christoph Hellwig
2020-06-29 9:31 ` Johannes Thumshirn
[not found] ` <20200627073159.2447325-2-hch-jcswGhMUV9g@public.gmane.org>
2020-07-08 14:02 ` Mike Snitzer
[not found] ` <20200627073159.2447325-1-hch-jcswGhMUV9g@public.gmane.org>
2020-06-27 7:31 ` [PATCH 02/14] block: remove bio_disassociate_blkg Christoph Hellwig
2020-06-29 9:33 ` Johannes Thumshirn
2020-06-27 7:31 ` [PATCH 08/14] block: bypass blkg_tryget_closest for the root_blkg Christoph Hellwig
2020-06-27 7:31 ` [PATCH 12/14] blk-cgroup: move rcu locking from blkcg_bio_issue_check to blk_throtl_bio Christoph Hellwig
2020-06-27 7:31 ` [PATCH 03/14] block: really clone the block cgroup in bio_clone_blkg_association Christoph Hellwig
2020-06-29 9:37 ` Johannes Thumshirn
2020-06-27 7:31 ` [PATCH 04/14] block: merge __bio_associate_blkg into bio_associate_blkg_from_css Christoph Hellwig
2020-06-29 9:55 ` Johannes Thumshirn
2020-06-27 7:31 ` [PATCH 05/14] block: move bio_associate_blkg_from_page to mm/page_io.c Christoph Hellwig
2020-06-29 9:59 ` Johannes Thumshirn
2020-06-29 10:08 ` Johannes Thumshirn
2020-06-27 7:31 ` [PATCH 06/14] block: move the bio cgroup associatation helpers to blk-cgroup.c Christoph Hellwig
2020-06-29 11:51 ` Johannes Thumshirn
2020-06-27 7:31 ` [PATCH 07/14] block: merge blkg_lookup_create and __blkg_lookup_create Christoph Hellwig
2020-06-29 12:21 ` Johannes Thumshirn
2020-06-27 7:31 ` Christoph Hellwig [this message]
2020-06-27 7:31 ` [PATCH 10/14] blk-cgroup: remove the !bio->bi_blkg check in blkcg_bio_issue_check Christoph Hellwig
2020-06-27 7:31 ` [PATCH 11/14] cgroup: unexport cgroup_rstat_updated Christoph Hellwig
2020-06-27 7:31 ` [PATCH 13/14] blk-cgroup: remove blkcg_bio_issue_check Christoph Hellwig
2020-06-27 7:31 ` [PATCH 14/14] blk-cgroup: remove a dead check in blk_throtl_bio Christoph Hellwig
2020-06-29 8:05 ` drive-by blk-cgroup cleanups Johannes Thumshirn
2020-06-29 8:08 ` Christoph Hellwig
2020-06-29 8:12 ` Johannes Thumshirn
2020-06-29 13:56 ` Tejun Heo
2020-06-29 15:09 ` Jens Axboe
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