On Mon, Jun 04, 2012 at 12:08:09AM -0700, Tejun Heo wrote:
> Currently, blkcg_activate_policy() depends on %GFP_ATOMIC allocation
> from __blkg_lookup_create() for root blkcg creation. This could make
> policy fail unnecessarily.
>
> Make blkg_alloc() take @gfp_mask, __blkg_lookup_create() take an
> optional @new_blkg for preallocated blkg, and blkcg_activate_policy()
> preload radix tree and preallocate blkg with %GFP_KERNEL before trying
> to create the root blkg.
>
> v2: __blkg_lookup_create() was returning %NULL on blkg alloc failure
> instead of ERR_PTR() value. Fixed.
>
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Looks good to me.
Acked-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
Vivek
> ---
> block/blk-cgroup.c | 59 +++++++++++++++++++++++++++++++++++++--------------
> 1 files changed, 43 insertions(+), 16 deletions(-)
>
> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
> index af61db0..cbeeb54 100644
> --- a/block/blk-cgroup.c
> +++ b/block/blk-cgroup.c
> @@ -91,16 +91,18 @@ static void blkg_free(struct blkcg_gq *blkg)
> * blkg_alloc - allocate a blkg
> * @blkcg: block cgroup the new blkg is associated with
> * @q: request_queue the new blkg is associated with
> + * @gfp_mask: allocation mask to use
> *
> * Allocate a new blkg assocating @blkcg and @q.
> */
> -static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q)
> +static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q,
> + gfp_t gfp_mask)
> {
> struct blkcg_gq *blkg;
> int i;
>
> /* alloc and init base part */
> - blkg = kzalloc_node(sizeof(*blkg), GFP_ATOMIC, q->node);
> + blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node);
> if (!blkg)
> return NULL;
>
> @@ -117,7 +119,7 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q)
> continue;
>
> /* alloc per-policy data and attach it to blkg */
> - pd = kzalloc_node(pol->pd_size, GFP_ATOMIC, q->node);
> + pd = kzalloc_node(pol->pd_size, gfp_mask, q->node);
> if (!pd) {
> blkg_free(blkg);
> return NULL;
> @@ -175,8 +177,13 @@ struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q)
> }
> EXPORT_SYMBOL_GPL(blkg_lookup);
>
> +/*
> + * If @new_blkg is %NULL, this function tries to allocate a new one as
> + * necessary using %GFP_ATOMIC. @new_blkg is always consumed on return.
> + */
> static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
> - struct request_queue *q)
> + struct request_queue *q,
> + struct blkcg_gq *new_blkg)
> {
> struct blkcg_gq *blkg;
> int ret;
> @@ -188,18 +195,24 @@ static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
> blkg = __blkg_lookup(blkcg, q);
> if (blkg) {
> rcu_assign_pointer(blkcg->blkg_hint, blkg);
> - return blkg;
> + goto out_free;
> }
>
> /* blkg holds a reference to blkcg */
> - if (!css_tryget(&blkcg->css))
> - return ERR_PTR(-EINVAL);
> + if (!css_tryget(&blkcg->css)) {
> + blkg = ERR_PTR(-EINVAL);
> + goto out_free;
> + }
>
> /* allocate */
> - ret = -ENOMEM;
> - blkg = blkg_alloc(blkcg, q);
> - if (unlikely(!blkg))
> - goto err_put;
> + if (!new_blkg) {
> + new_blkg = blkg_alloc(blkcg, q, GFP_ATOMIC);
> + if (unlikely(!new_blkg)) {
> + blkg = ERR_PTR(-ENOMEM);
> + goto out_put;
> + }
> + }
> + blkg = new_blkg;
>
> /* insert */
> spin_lock(&blkcg->lock);
> @@ -212,10 +225,13 @@ static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
>
> if (!ret)
> return blkg;
> -err_put:
> +
> + blkg = ERR_PTR(ret);
> +out_put:
> css_put(&blkcg->css);
> - blkg_free(blkg);
> - return ERR_PTR(ret);
> +out_free:
> + blkg_free(new_blkg);
> + return blkg;
> }
>
> struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
> @@ -227,7 +243,7 @@ struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
> */
> if (unlikely(blk_queue_bypass(q)))
> return ERR_PTR(blk_queue_dead(q) ? -EINVAL : -EBUSY);
> - return __blkg_lookup_create(blkcg, q);
> + return __blkg_lookup_create(blkcg, q, NULL);
> }
> EXPORT_SYMBOL_GPL(blkg_lookup_create);
>
> @@ -727,19 +743,30 @@ int blkcg_activate_policy(struct request_queue *q,
> struct blkcg_gq *blkg;
> struct blkg_policy_data *pd, *n;
> int cnt = 0, ret;
> + bool preloaded;
>
> if (blkcg_policy_enabled(q, pol))
> return 0;
>
> + /* preallocations for root blkg */
> + blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL);
> + if (!blkg)
> + return -ENOMEM;
> +
> + preloaded = !radix_tree_preload(GFP_KERNEL);
> +
> blk_queue_bypass_start(q);
>
> /* make sure the root blkg exists and count the existing blkgs */
> spin_lock_irq(q->queue_lock);
>
> rcu_read_lock();
> - blkg = __blkg_lookup_create(&blkcg_root, q);
> + blkg = __blkg_lookup_create(&blkcg_root, q, blkg);
> rcu_read_unlock();
>
> + if (preloaded)
> + radix_tree_preload_end();
> +
> if (IS_ERR(blkg)) {
> ret = PTR_ERR(blkg);
> goto out_unlock;
> --
> 1.7.7.3
_______________________________________________
Containers mailing list
Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linuxfoundation.org/mailman/listinfo/containers
