Re: [PATCH] cfq-iosched: add symmetric reference wrappers
From: Justin TerAvest
Date: Thu Mar 17 2011 - 11:43:10 EST
Sorry, feel free to disregard the first line. I believe the patch is good.
Let me know if I should remail the patch with that question at the top removed.
Thanks,
Justin
On Thu, Mar 17, 2011 at 8:31 AM, Justin TerAvest <teravest@xxxxxxxxxx> wrote:
> Can you sanity check this before I send it out?
>
> The cfq_group and cfq_queue objects did not have symmetric
> wrapper functions and many of the reference taking was
> open coded. For clarity add the following wrappers:
>
> cfq_group:
> - cfq_get_group_ref()
> - cfq_put_group_ref()
>
> cfq_queue:
> - cfq_get_queue_ref()
> - cfq_put_queue_ref()
>
> The use of '_ref' was done not to collide with existing
> function names.
>
> Signed-off-by: Justin TerAvest <teravest@xxxxxxxxxx>
> ---
> block/cfq-iosched.c | 95 +++++++++++++++++++++++++++++---------------------
> 1 files changed, 55 insertions(+), 40 deletions(-)
>
> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
> index 89e0d1c..e3136d7 100644
> --- a/block/cfq-iosched.c
> +++ b/block/cfq-iosched.c
> @@ -301,6 +301,11 @@ struct cfq_data {
> struct rcu_head rcu;
> };
>
> +static void cfq_get_group_ref(struct cfq_group *cfqg);
> +static void cfq_put_group_ref(struct cfq_group *cfqg);
> +static void cfq_get_queue_ref(struct cfq_queue *cfqq);
> +static void cfq_put_queue_ref(struct cfq_queue *cfqq);
> +
> static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
>
> static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
> @@ -1019,7 +1024,7 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
> * elevator which will be dropped by either elevator exit
> * or cgroup deletion path depending on who is exiting first.
> */
> - cfqg->ref = 1;
> + cfq_get_group_ref(cfqg);
>
> /*
> * Add group onto cgroup list. It might happen that bdi->dev is
> @@ -1062,24 +1067,12 @@ static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
> return cfqg;
> }
>
> -static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
> +static void cfq_get_group_ref(struct cfq_group *cfqg)
> {
> cfqg->ref++;
> - return cfqg;
> }
>
> -static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
> -{
> - /* Currently, all async queues are mapped to root group */
> - if (!cfq_cfqq_sync(cfqq))
> - cfqg = &cfqq->cfqd->root_group;
> -
> - cfqq->cfqg = cfqg;
> - /* cfqq reference on cfqg */
> - cfqq->cfqg->ref++;
> -}
> -
> -static void cfq_put_cfqg(struct cfq_group *cfqg)
> +static void cfq_put_group_ref(struct cfq_group *cfqg)
> {
> struct cfq_rb_root *st;
> int i, j;
> @@ -1093,6 +1086,17 @@ static void cfq_put_cfqg(struct cfq_group *cfqg)
> kfree(cfqg);
> }
>
> +static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
> +{
> + /* Currently, all async queues are mapped to root group */
> + if (!cfq_cfqq_sync(cfqq))
> + cfqg = &cfqq->cfqd->root_group;
> +
> + cfqq->cfqg = cfqg;
> + /* cfqq reference on cfqg */
> + cfq_get_group_ref(cfqq->cfqg);
> +}
> +
> static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
> {
> /* Something wrong if we are trying to remove same group twice */
> @@ -1104,7 +1108,7 @@ static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
> * Put the reference taken at the time of creation so that when all
> * queues are gone, group can be destroyed.
> */
> - cfq_put_cfqg(cfqg);
> + cfq_put_group_ref(cfqg);
> }
>
> static void cfq_release_cfq_groups(struct cfq_data *cfqd)
> @@ -1148,14 +1152,18 @@ void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
> }
>
> #else /* GROUP_IOSCHED */
> -static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
> +
> +static void cfq_get_group_ref(struct cfq_group *cfqg)
> {
> - return &cfqd->root_group;
> }
>
> -static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
> +static void cfq_put_group_ref(struct cfq_group *cfqg)
> {
> - return cfqg;
> +}
> +
> +static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
> +{
> + return &cfqd->root_group;
> }
>
> static inline void
> @@ -1164,7 +1172,6 @@ cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
> }
>
> static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
> -static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
>
> #endif /* GROUP_IOSCHED */
>
> @@ -2524,6 +2531,11 @@ static int cfq_dispatch_requests(struct request_queue *q, int force)
> return 1;
> }
>
> +static void cfq_get_queue_ref(struct cfq_queue *cfqq)
> +{
> + cfqq->ref++;
> +}
> +
> /*
> * task holds one reference to the queue, dropped when task exits. each rq
> * in-flight on this queue also holds a reference, dropped when rq is freed.
> @@ -2531,7 +2543,7 @@ static int cfq_dispatch_requests(struct request_queue *q, int force)
> * Each cfq queue took a reference on the parent group. Drop it now.
> * queue lock must be held here.
> */
> -static void cfq_put_queue(struct cfq_queue *cfqq)
> +static void cfq_put_queue_ref(struct cfq_queue *cfqq)
> {
> struct cfq_data *cfqd = cfqq->cfqd;
> struct cfq_group *cfqg;
> @@ -2554,7 +2566,7 @@ static void cfq_put_queue(struct cfq_queue *cfqq)
>
> BUG_ON(cfq_cfqq_on_rr(cfqq));
> kmem_cache_free(cfq_pool, cfqq);
> - cfq_put_cfqg(cfqg);
> + cfq_put_group_ref(cfqg);
> }
>
> /*
> @@ -2659,7 +2671,7 @@ static void cfq_put_cooperator(struct cfq_queue *cfqq)
> break;
> }
> next = __cfqq->new_cfqq;
> - cfq_put_queue(__cfqq);
> + cfq_put_queue_ref(__cfqq);
> __cfqq = next;
> }
> }
> @@ -2673,7 +2685,7 @@ static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
>
> cfq_put_cooperator(cfqq);
>
> - cfq_put_queue(cfqq);
> + cfq_put_queue_ref(cfqq);
> }
>
> static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
> @@ -2815,7 +2827,7 @@ static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
> GFP_ATOMIC);
> if (new_cfqq) {
> cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
> - cfq_put_queue(cfqq);
> + cfq_put_queue_ref(cfqq);
> }
> }
>
> @@ -2874,7 +2886,7 @@ static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
> */
> cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
> cic_set_cfqq(cic, NULL, 1);
> - cfq_put_queue(sync_cfqq);
> + cfq_put_queue_ref(sync_cfqq);
> }
>
> spin_unlock_irqrestore(q->queue_lock, flags);
> @@ -2975,11 +2987,11 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
> * pin the queue now that it's allocated, scheduler exit will prune it
> */
> if (!is_sync && !(*async_cfqq)) {
> - cfqq->ref++;
> + cfq_get_queue_ref(cfqq);
> *async_cfqq = cfqq;
> }
>
> - cfqq->ref++;
> + cfq_get_queue_ref(cfqq);
> return cfqq;
> }
>
> @@ -3604,10 +3616,10 @@ static void cfq_put_request(struct request *rq)
> rq->elevator_private[1] = NULL;
>
> /* Put down rq reference on cfqg */
> - cfq_put_cfqg(RQ_CFQG(rq));
> + cfq_put_group_ref(RQ_CFQG(rq));
> rq->elevator_private[2] = NULL;
>
> - cfq_put_queue(cfqq);
> + cfq_put_queue_ref(cfqq);
> }
> }
>
> @@ -3618,7 +3630,7 @@ cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
> cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
> cic_set_cfqq(cic, cfqq->new_cfqq, 1);
> cfq_mark_cfqq_coop(cfqq->new_cfqq);
> - cfq_put_queue(cfqq);
> + cfq_put_queue_ref(cfqq);
> return cic_to_cfqq(cic, 1);
> }
>
> @@ -3640,7 +3652,7 @@ split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
>
> cfq_put_cooperator(cfqq);
>
> - cfq_put_queue(cfqq);
> + cfq_put_queue_ref(cfqq);
> return NULL;
> }
> /*
> @@ -3693,10 +3705,12 @@ new_queue:
>
> cfqq->allocated[rw]++;
>
> - cfqq->ref++;
> + cfq_get_queue_ref(cfqq);
> rq->elevator_private[0] = cic;
> rq->elevator_private[1] = cfqq;
> - rq->elevator_private[2] = cfq_ref_get_cfqg(cfqq->cfqg);
> +
> + cfq_get_group_ref(cfqq->cfqg);
> + rq->elevator_private[2] = cfqq->cfqg;
> spin_unlock_irqrestore(q->queue_lock, flags);
> return 0;
>
> @@ -3789,13 +3803,13 @@ static void cfq_put_async_queues(struct cfq_data *cfqd)
>
> for (i = 0; i < IOPRIO_BE_NR; i++) {
> if (cfqd->async_cfqq[0][i])
> - cfq_put_queue(cfqd->async_cfqq[0][i]);
> + cfq_put_queue_ref(cfqd->async_cfqq[0][i]);
> if (cfqd->async_cfqq[1][i])
> - cfq_put_queue(cfqd->async_cfqq[1][i]);
> + cfq_put_queue_ref(cfqd->async_cfqq[1][i]);
> }
>
> if (cfqd->async_idle_cfqq)
> - cfq_put_queue(cfqd->async_idle_cfqq);
> + cfq_put_queue_ref(cfqd->async_idle_cfqq);
> }
>
> static void cfq_cfqd_free(struct rcu_head *head)
> @@ -3893,9 +3907,10 @@ static void *cfq_init_queue(struct request_queue *q)
> #ifdef CONFIG_CFQ_GROUP_IOSCHED
> /*
> * Take a reference to root group which we never drop. This is just
> - * to make sure that cfq_put_cfqg() does not try to kfree root group
> + * to make sure that cfq_put_group_ref() does not try to kfree
> + * root group
> */
> - cfqg->ref = 1;
> + cfq_get_group_ref(cfqg);
> rcu_read_lock();
> cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
> (void *)cfqd, 0);
> --
> 1.7.3.1
>
>
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