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Message-Id: <20250925081525.700639-10-yukuai1@huaweicloud.com>
Date: Thu, 25 Sep 2025 16:15:24 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: tj@...nel.org,
ming.lei@...hat.com,
nilay@...ux.ibm.com,
hch@....de,
josef@...icpanda.com,
axboe@...nel.dk,
akpm@...ux-foundation.org,
vgoyal@...hat.com
Cc: cgroups@...r.kernel.org,
linux-block@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-mm@...ck.org,
yukuai3@...wei.com,
yukuai1@...weicloud.com,
yi.zhang@...wei.com,
yangerkun@...wei.com,
johnny.chenyi@...wei.com
Subject: [PATCH 09/10] blk-cgroup: remove preallocate blkg for blkg_create()
From: Yu Kuai <yukuai3@...wei.com>
Now that blkg_create is protected with blkcg_mutex, there is no need to
preallocate blkg, remove related code.
Signed-off-by: Yu Kuai <yukuai3@...wei.com>
---
block/blk-cgroup.c | 91 +++++++++++++++++-----------------------------
1 file changed, 33 insertions(+), 58 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index bfc74cfebd3e..60b8c742f876 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -364,10 +364,9 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct gendisk *disk,
* If @new_blkg is %NULL, this function tries to allocate a new one as
* necessary using %GFP_NOWAIT. @new_blkg is always consumed on return.
*/
-static struct blkcg_gq *blkg_create(struct blkcg *blkcg, struct gendisk *disk,
- struct blkcg_gq *new_blkg)
+static struct blkcg_gq *blkg_create(struct blkcg *blkcg, struct gendisk *disk)
{
- struct blkcg_gq *blkg;
+ struct blkcg_gq *blkg = NULL;
int i, ret;
lockdep_assert_held(&disk->queue->blkcg_mutex);
@@ -384,15 +383,11 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, struct gendisk *disk,
goto err_free_blkg;
}
- /* allocate */
- if (!new_blkg) {
- new_blkg = blkg_alloc(blkcg, disk, GFP_NOWAIT);
- if (unlikely(!new_blkg)) {
- ret = -ENOMEM;
- goto err_put_css;
- }
+ blkg = blkg_alloc(blkcg, disk, GFP_NOIO);
+ if (unlikely(!blkg)) {
+ ret = -ENOMEM;
+ goto err_put_css;
}
- blkg = new_blkg;
/* link parent */
if (blkcg_parent(blkcg)) {
@@ -415,35 +410,34 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, struct gendisk *disk,
/* insert */
spin_lock(&blkcg->lock);
ret = radix_tree_insert(&blkcg->blkg_tree, disk->queue->id, blkg);
- if (likely(!ret)) {
- hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
- list_add(&blkg->q_node, &disk->queue->blkg_list);
+ if (unlikely(ret)) {
+ spin_unlock(&blkcg->lock);
+ blkg_put(blkg);
+ return ERR_PTR(ret);
+ }
- for (i = 0; i < BLKCG_MAX_POLS; i++) {
- struct blkcg_policy *pol = blkcg_policy[i];
+ hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
+ list_add(&blkg->q_node, &disk->queue->blkg_list);
- if (blkg->pd[i]) {
- if (pol->pd_online_fn)
- pol->pd_online_fn(blkg->pd[i]);
- blkg->pd[i]->online = true;
- }
+ for (i = 0; i < BLKCG_MAX_POLS; i++) {
+ struct blkcg_policy *pol = blkcg_policy[i];
+
+ if (blkg->pd[i]) {
+ if (pol->pd_online_fn)
+ pol->pd_online_fn(blkg->pd[i]);
+ blkg->pd[i]->online = true;
}
}
+
blkg->online = true;
spin_unlock(&blkcg->lock);
-
- if (!ret)
- return blkg;
-
- /* @blkg failed fully initialized, use the usual release path */
- blkg_put(blkg);
- return ERR_PTR(ret);
+ return blkg;
err_put_css:
css_put(&blkcg->css);
err_free_blkg:
- if (new_blkg)
- blkg_free(new_blkg);
+ if (blkg)
+ blkg_free(blkg);
return ERR_PTR(ret);
}
@@ -498,7 +492,7 @@ static struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
parent = blkcg_parent(parent);
}
- blkg = blkg_create(pos, disk, NULL);
+ blkg = blkg_create(pos, disk);
if (IS_ERR(blkg)) {
blkg = ret_blkg;
break;
@@ -879,7 +873,6 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
while (true) {
struct blkcg *pos = blkcg;
struct blkcg *parent;
- struct blkcg_gq *new_blkg;
parent = blkcg_parent(blkcg);
while (parent && !blkg_lookup(parent, q)) {
@@ -887,23 +880,14 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
parent = blkcg_parent(parent);
}
- new_blkg = blkg_alloc(pos, disk, GFP_NOIO);
- if (unlikely(!new_blkg)) {
- ret = -ENOMEM;
- goto fail_unlock;
- }
-
if (!blkcg_policy_enabled(q, pol)) {
- blkg_free(new_blkg);
ret = -EOPNOTSUPP;
goto fail_unlock;
}
blkg = blkg_lookup(pos, q);
- if (blkg) {
- blkg_free(new_blkg);
- } else {
- blkg = blkg_create(pos, disk, new_blkg);
+ if (!blkg) {
+ blkg = blkg_create(pos, disk);
if (IS_ERR(blkg)) {
ret = PTR_ERR(blkg);
goto fail_unlock;
@@ -1468,27 +1452,18 @@ void blkg_init_queue(struct request_queue *q)
int blkcg_init_disk(struct gendisk *disk)
{
struct request_queue *q = disk->queue;
- struct blkcg_gq *new_blkg, *blkg;
-
- new_blkg = blkg_alloc(&blkcg_root, disk, GFP_KERNEL);
- if (!new_blkg)
- return -ENOMEM;
+ struct blkcg_gq *blkg;
+ /* Make sure the root blkg exists. */
mutex_lock(&q->blkcg_mutex);
+ blkg = blkg_create(&blkcg_root, disk);
+ mutex_unlock(&q->blkcg_mutex);
- /* Make sure the root blkg exists. */
- blkg = blkg_create(&blkcg_root, disk, new_blkg);
if (IS_ERR(blkg))
- goto err_unlock;
- q->root_blkg = blkg;
-
- mutex_unlock(&q->blkcg_mutex);
+ return PTR_ERR(blkg);
+ q->root_blkg = blkg;
return 0;
-
-err_unlock:
- mutex_unlock(&q->blkcg_mutex);
- return PTR_ERR(blkg);
}
void blkcg_exit_disk(struct gendisk *disk)
--
2.39.2
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