blkcg: remove bio->bi_css and instead use bio->bi_blkg
Prior patches ensured that any bio that interacts with a request_queue
is properly associated with a blkg. This makes bio->bi_css unnecessary
as blkg maintains a reference to blkcg already.
This removes the bio field bi_css and transfers corresponding uses to
access via bi_blkg.
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/bio.c b/block/bio.c
index b42477b..2b6bc7b 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -610,7 +610,7 @@ void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
bio->bi_iter = bio_src->bi_iter;
bio->bi_io_vec = bio_src->bi_io_vec;
- bio_clone_blkcg_association(bio, bio_src);
+ bio_clone_blkg_association(bio, bio_src);
blkcg_bio_issue_init(bio);
}
EXPORT_SYMBOL(__bio_clone_fast);
@@ -1958,34 +1958,6 @@ EXPORT_SYMBOL(bioset_init_from_src);
#ifdef CONFIG_BLK_CGROUP
/**
- * bio_associate_blkcg - associate a bio with the specified blkcg
- * @bio: target bio
- * @blkcg_css: css of the blkcg to associate
- *
- * Associate @bio with the blkcg specified by @blkcg_css. Block layer will
- * treat @bio as if it were issued by a task which belongs to the blkcg.
- *
- * This function takes an extra reference of @blkcg_css which will be put
- * when @bio is released. The caller must own @bio and is responsible for
- * synchronizing calls to this function. If @blkcg_css is %NULL, a call to
- * blkcg_get_css() finds the current css from the kthread or task.
- */
-int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css)
-{
- if (unlikely(bio->bi_css))
- return -EBUSY;
-
- if (blkcg_css)
- css_get(blkcg_css);
- else
- blkcg_css = blkcg_get_css();
-
- bio->bi_css = blkcg_css;
- return 0;
-}
-EXPORT_SYMBOL_GPL(bio_associate_blkcg);
-
-/**
* bio_disassociate_blkg - puts back the blkg reference if associated
* @bio: target bio
*
@@ -1994,6 +1966,8 @@ EXPORT_SYMBOL_GPL(bio_associate_blkcg);
void bio_disassociate_blkg(struct bio *bio)
{
if (bio->bi_blkg) {
+ /* a ref is always taken on css */
+ css_put(&bio_blkcg(bio)->css);
blkg_put(bio->bi_blkg);
bio->bi_blkg = NULL;
}
@@ -2047,7 +2021,6 @@ void bio_associate_blkg_from_css(struct bio *bio,
struct cgroup_subsys_state *css)
{
css_get(css);
- bio->bi_css = css;
__bio_associate_blkg_from_css(bio, css);
}
EXPORT_SYMBOL_GPL(bio_associate_blkg_from_css);
@@ -2066,13 +2039,10 @@ void bio_associate_blkg_from_page(struct bio *bio, struct page *page)
{
struct cgroup_subsys_state *css;
- if (unlikely(bio->bi_css))
- return;
if (!page->mem_cgroup)
return;
css = cgroup_get_e_css(page->mem_cgroup->css.cgroup, &io_cgrp_subsys);
- bio->bi_css = css;
__bio_associate_blkg_from_css(bio, css);
}
#endif /* CONFIG_MEMCG */
@@ -2094,8 +2064,10 @@ void bio_associate_blkg(struct bio *bio)
rcu_read_lock();
- bio_associate_blkcg(bio, NULL);
- blkcg = bio_blkcg(bio);
+ if (bio->bi_blkg)
+ blkcg = bio->bi_blkg->blkcg;
+ else
+ blkcg = css_to_blkcg(blkcg_get_css());
if (!blkcg->css.parent) {
__bio_associate_blkg(bio, q->root_blkg);
@@ -2115,27 +2087,22 @@ EXPORT_SYMBOL_GPL(bio_associate_blkg);
*/
void bio_disassociate_task(struct bio *bio)
{
- if (bio->bi_css) {
- css_put(bio->bi_css);
- bio->bi_css = NULL;
- }
bio_disassociate_blkg(bio);
}
/**
- * bio_clone_blkcg_association - clone blkcg association from src to dst bio
+ * bio_clone_blkg_association - clone blkg association from src to dst bio
* @dst: destination bio
* @src: source bio
*/
-void bio_clone_blkcg_association(struct bio *dst, struct bio *src)
+void bio_clone_blkg_association(struct bio *dst, struct bio *src)
{
- if (src->bi_css)
- WARN_ON(bio_associate_blkcg(dst, src->bi_css));
-
- if (src->bi_blkg)
+ if (src->bi_blkg) {
+ css_get(&bio_blkcg(src)->css);
__bio_associate_blkg(dst, src->bi_blkg);
+ }
}
-EXPORT_SYMBOL_GPL(bio_clone_blkcg_association);
+EXPORT_SYMBOL_GPL(bio_clone_blkg_association);
#endif /* CONFIG_BLK_CGROUP */
static void __init biovec_init_slabs(void)