From 8bd435b30ecacb69bbb8b2d3e251f770b807c5b2 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 13 Apr 2012 13:11:28 -0700 Subject: blkcg: remove static policy ID enums Remove BLKIO_POLICY_* enums and let blkio_policy_register() allocate @pol->plid dynamically on registration. The maximum number of blkcg policies which can be registered at the same time is defined by BLKCG_MAX_POLS constant added to include/linux/blkdev.h. Note that blkio_policy_register() now may fail. Policy init functions updated accordingly and unnecessary ifdefs removed from cfq_init(). Signed-off-by: Tejun Heo Cc: Vivek Goyal Signed-off-by: Jens Axboe --- block/blk-cgroup.c | 59 ++++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 44 insertions(+), 15 deletions(-) (limited to 'block/blk-cgroup.c') diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index b123152..2d4d7d6 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -31,7 +31,7 @@ static LIST_HEAD(all_q_list); struct blkio_cgroup blkio_root_cgroup = { .cfq_weight = 2 * CFQ_WEIGHT_DEFAULT }; EXPORT_SYMBOL_GPL(blkio_root_cgroup); -static struct blkio_policy_type *blkio_policy[BLKIO_NR_POLICIES]; +static struct blkio_policy_type *blkio_policy[BLKCG_MAX_POLS]; struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup) { @@ -67,7 +67,7 @@ static void blkg_free(struct blkio_group *blkg) if (!blkg) return; - for (i = 0; i < BLKIO_NR_POLICIES; i++) { + for (i = 0; i < BLKCG_MAX_POLS; i++) { struct blkio_policy_type *pol = blkio_policy[i]; struct blkg_policy_data *pd = blkg->pd[i]; @@ -107,7 +107,7 @@ static struct blkio_group *blkg_alloc(struct blkio_cgroup *blkcg, blkg->refcnt = 1; cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path)); - for (i = 0; i < BLKIO_NR_POLICIES; i++) { + for (i = 0; i < BLKCG_MAX_POLS; i++) { struct blkio_policy_type *pol = blkio_policy[i]; struct blkg_policy_data *pd; @@ -127,7 +127,7 @@ static struct blkio_group *blkg_alloc(struct blkio_cgroup *blkcg, } /* invoke per-policy init */ - for (i = 0; i < BLKIO_NR_POLICIES; i++) { + for (i = 0; i < BLKCG_MAX_POLS; i++) { struct blkio_policy_type *pol = blkio_policy[i]; if (pol) @@ -320,7 +320,7 @@ blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val) * anyway. If you get hit by a race, retry. */ hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) { - for (i = 0; i < BLKIO_NR_POLICIES; i++) { + for (i = 0; i < BLKCG_MAX_POLS; i++) { struct blkio_policy_type *pol = blkio_policy[i]; if (pol && pol->ops.blkio_reset_group_stats_fn) @@ -729,46 +729,75 @@ struct cgroup_subsys blkio_subsys = { }; EXPORT_SYMBOL_GPL(blkio_subsys); -void blkio_policy_register(struct blkio_policy_type *blkiop) +/** + * blkio_policy_register - register a blkcg policy + * @blkiop: blkcg policy to register + * + * Register @blkiop with blkcg core. Might sleep and @blkiop may be + * modified on successful registration. Returns 0 on success and -errno on + * failure. + */ +int blkio_policy_register(struct blkio_policy_type *blkiop) { struct request_queue *q; + int i, ret; mutex_lock(&blkcg_pol_mutex); - blkcg_bypass_start(); + /* find an empty slot */ + ret = -ENOSPC; + for (i = 0; i < BLKCG_MAX_POLS; i++) + if (!blkio_policy[i]) + break; + if (i >= BLKCG_MAX_POLS) + goto out_unlock; - BUG_ON(blkio_policy[blkiop->plid]); - blkio_policy[blkiop->plid] = blkiop; + /* register and update blkgs */ + blkiop->plid = i; + blkio_policy[i] = blkiop; + + blkcg_bypass_start(); list_for_each_entry(q, &all_q_list, all_q_node) update_root_blkg_pd(q, blkiop); - blkcg_bypass_end(); + /* everything is in place, add intf files for the new policy */ if (blkiop->cftypes) WARN_ON(cgroup_add_cftypes(&blkio_subsys, blkiop->cftypes)); - + ret = 0; +out_unlock: mutex_unlock(&blkcg_pol_mutex); + return ret; } EXPORT_SYMBOL_GPL(blkio_policy_register); +/** + * blkiop_policy_unregister - unregister a blkcg policy + * @blkiop: blkcg policy to unregister + * + * Undo blkio_policy_register(@blkiop). Might sleep. + */ void blkio_policy_unregister(struct blkio_policy_type *blkiop) { struct request_queue *q; mutex_lock(&blkcg_pol_mutex); + if (WARN_ON(blkio_policy[blkiop->plid] != blkiop)) + goto out_unlock; + + /* kill the intf files first */ if (blkiop->cftypes) cgroup_rm_cftypes(&blkio_subsys, blkiop->cftypes); - blkcg_bypass_start(); - - BUG_ON(blkio_policy[blkiop->plid] != blkiop); + /* unregister and update blkgs */ blkio_policy[blkiop->plid] = NULL; + blkcg_bypass_start(); list_for_each_entry(q, &all_q_list, all_q_node) update_root_blkg_pd(q, blkiop); blkcg_bypass_end(); - +out_unlock: mutex_unlock(&blkcg_pol_mutex); } EXPORT_SYMBOL_GPL(blkio_policy_unregister); -- cgit v1.1