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 <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tejun Heo
Jens Axboe
parent
ec399347d3
commit
8bd435b30e
5 changed files with 69 additions and 41 deletions
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@ -31,7 +31,7 @@ static LIST_HEAD(all_q_list);
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struct blkio_cgroup blkio_root_cgroup = { .cfq_weight = 2 * CFQ_WEIGHT_DEFAULT };
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EXPORT_SYMBOL_GPL(blkio_root_cgroup);
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static struct blkio_policy_type *blkio_policy[BLKIO_NR_POLICIES];
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static struct blkio_policy_type *blkio_policy[BLKCG_MAX_POLS];
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struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
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{
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@ -67,7 +67,7 @@ static void blkg_free(struct blkio_group *blkg)
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if (!blkg)
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return;
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for (i = 0; i < BLKIO_NR_POLICIES; i++) {
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for (i = 0; i < BLKCG_MAX_POLS; i++) {
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struct blkio_policy_type *pol = blkio_policy[i];
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struct blkg_policy_data *pd = blkg->pd[i];
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@ -107,7 +107,7 @@ static struct blkio_group *blkg_alloc(struct blkio_cgroup *blkcg,
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blkg->refcnt = 1;
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cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
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for (i = 0; i < BLKIO_NR_POLICIES; i++) {
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for (i = 0; i < BLKCG_MAX_POLS; i++) {
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struct blkio_policy_type *pol = blkio_policy[i];
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struct blkg_policy_data *pd;
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@ -127,7 +127,7 @@ static struct blkio_group *blkg_alloc(struct blkio_cgroup *blkcg,
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}
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/* invoke per-policy init */
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for (i = 0; i < BLKIO_NR_POLICIES; i++) {
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for (i = 0; i < BLKCG_MAX_POLS; i++) {
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struct blkio_policy_type *pol = blkio_policy[i];
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if (pol)
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@ -320,7 +320,7 @@ blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
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* anyway. If you get hit by a race, retry.
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*/
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hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
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for (i = 0; i < BLKIO_NR_POLICIES; i++) {
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for (i = 0; i < BLKCG_MAX_POLS; i++) {
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struct blkio_policy_type *pol = blkio_policy[i];
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if (pol && pol->ops.blkio_reset_group_stats_fn)
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@ -729,46 +729,75 @@ struct cgroup_subsys blkio_subsys = {
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};
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EXPORT_SYMBOL_GPL(blkio_subsys);
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void blkio_policy_register(struct blkio_policy_type *blkiop)
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/**
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* blkio_policy_register - register a blkcg policy
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* @blkiop: blkcg policy to register
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*
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* Register @blkiop with blkcg core. Might sleep and @blkiop may be
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* modified on successful registration. Returns 0 on success and -errno on
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* failure.
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*/
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int blkio_policy_register(struct blkio_policy_type *blkiop)
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{
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struct request_queue *q;
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int i, ret;
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mutex_lock(&blkcg_pol_mutex);
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blkcg_bypass_start();
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/* find an empty slot */
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ret = -ENOSPC;
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for (i = 0; i < BLKCG_MAX_POLS; i++)
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if (!blkio_policy[i])
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break;
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if (i >= BLKCG_MAX_POLS)
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goto out_unlock;
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BUG_ON(blkio_policy[blkiop->plid]);
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blkio_policy[blkiop->plid] = blkiop;
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/* register and update blkgs */
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blkiop->plid = i;
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blkio_policy[i] = blkiop;
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blkcg_bypass_start();
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list_for_each_entry(q, &all_q_list, all_q_node)
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update_root_blkg_pd(q, blkiop);
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blkcg_bypass_end();
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/* everything is in place, add intf files for the new policy */
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if (blkiop->cftypes)
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WARN_ON(cgroup_add_cftypes(&blkio_subsys, blkiop->cftypes));
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ret = 0;
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out_unlock:
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mutex_unlock(&blkcg_pol_mutex);
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return ret;
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}
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EXPORT_SYMBOL_GPL(blkio_policy_register);
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/**
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* blkiop_policy_unregister - unregister a blkcg policy
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* @blkiop: blkcg policy to unregister
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*
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* Undo blkio_policy_register(@blkiop). Might sleep.
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*/
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void blkio_policy_unregister(struct blkio_policy_type *blkiop)
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{
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struct request_queue *q;
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mutex_lock(&blkcg_pol_mutex);
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if (WARN_ON(blkio_policy[blkiop->plid] != blkiop))
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goto out_unlock;
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/* kill the intf files first */
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if (blkiop->cftypes)
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cgroup_rm_cftypes(&blkio_subsys, blkiop->cftypes);
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blkcg_bypass_start();
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BUG_ON(blkio_policy[blkiop->plid] != blkiop);
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/* unregister and update blkgs */
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blkio_policy[blkiop->plid] = NULL;
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blkcg_bypass_start();
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list_for_each_entry(q, &all_q_list, all_q_node)
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update_root_blkg_pd(q, blkiop);
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blkcg_bypass_end();
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out_unlock:
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mutex_unlock(&blkcg_pol_mutex);
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}
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EXPORT_SYMBOL_GPL(blkio_policy_unregister);
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@ -17,13 +17,6 @@
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#include <linux/u64_stats_sync.h>
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#include <linux/seq_file.h>
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enum blkio_policy_id {
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BLKIO_POLICY_PROP = 0, /* Proportional Bandwidth division */
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BLKIO_POLICY_THROTL, /* Throttling */
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BLKIO_NR_POLICIES,
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};
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/* Max limits for throttle policy */
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#define THROTL_IOPS_MAX UINT_MAX
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@ -86,7 +79,7 @@ struct blkio_group {
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/* reference count */
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int refcnt;
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struct blkg_policy_data *pd[BLKIO_NR_POLICIES];
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struct blkg_policy_data *pd[BLKCG_MAX_POLS];
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struct rcu_head rcu_head;
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};
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@ -103,7 +96,7 @@ struct blkio_policy_ops {
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struct blkio_policy_type {
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struct blkio_policy_ops ops;
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enum blkio_policy_id plid;
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int plid;
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size_t pdata_size; /* policy specific private data size */
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struct cftype *cftypes; /* cgroup files for the policy */
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};
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@ -113,7 +106,7 @@ extern void blkcg_drain_queue(struct request_queue *q);
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extern void blkcg_exit_queue(struct request_queue *q);
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/* Blkio controller policy registration */
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extern void blkio_policy_register(struct blkio_policy_type *);
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extern int blkio_policy_register(struct blkio_policy_type *);
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extern void blkio_policy_unregister(struct blkio_policy_type *);
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extern void blkg_destroy_all(struct request_queue *q, bool destroy_root);
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extern void update_root_blkg_pd(struct request_queue *q,
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@ -329,7 +322,7 @@ struct blkio_policy_type {
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static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
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static inline void blkcg_drain_queue(struct request_queue *q) { }
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static inline void blkcg_exit_queue(struct request_queue *q) { }
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static inline void blkio_policy_register(struct blkio_policy_type *blkiop) { }
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static inline int blkio_policy_register(struct blkio_policy_type *blkiop) { return 0; }
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static inline void blkio_policy_unregister(struct blkio_policy_type *blkiop) { }
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static inline void blkg_destroy_all(struct request_queue *q,
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bool destory_root) { }
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@ -1089,7 +1089,6 @@ static struct blkio_policy_type blkio_policy_throtl = {
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.blkio_exit_group_fn = throtl_exit_blkio_group,
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.blkio_reset_group_stats_fn = throtl_reset_group_stats,
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},
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.plid = BLKIO_POLICY_THROTL,
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.pdata_size = sizeof(struct throtl_grp),
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.cftypes = throtl_files,
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};
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@ -1271,8 +1270,7 @@ static int __init throtl_init(void)
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if (!kthrotld_workqueue)
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panic("Failed to create kthrotld\n");
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blkio_policy_register(&blkio_policy_throtl);
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return 0;
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return blkio_policy_register(&blkio_policy_throtl);
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}
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module_init(throtl_init);
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@ -4157,7 +4157,6 @@ static struct blkio_policy_type blkio_policy_cfq = {
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.blkio_init_group_fn = cfq_init_blkio_group,
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.blkio_reset_group_stats_fn = cfqg_stats_reset,
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},
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.plid = BLKIO_POLICY_PROP,
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.pdata_size = sizeof(struct cfq_group),
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.cftypes = cfq_blkcg_files,
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};
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@ -4181,27 +4180,31 @@ static int __init cfq_init(void)
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#else
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cfq_group_idle = 0;
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#endif
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ret = blkio_policy_register(&blkio_policy_cfq);
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if (ret)
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return ret;
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cfq_pool = KMEM_CACHE(cfq_queue, 0);
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if (!cfq_pool)
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return -ENOMEM;
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goto err_pol_unreg;
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ret = elv_register(&iosched_cfq);
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if (ret) {
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kmem_cache_destroy(cfq_pool);
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return ret;
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}
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if (ret)
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goto err_free_pool;
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#ifdef CONFIG_CFQ_GROUP_IOSCHED
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blkio_policy_register(&blkio_policy_cfq);
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#endif
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return 0;
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err_free_pool:
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kmem_cache_destroy(cfq_pool);
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err_pol_unreg:
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blkio_policy_unregister(&blkio_policy_cfq);
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return ret;
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}
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static void __exit cfq_exit(void)
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{
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#ifdef CONFIG_CFQ_GROUP_IOSCHED
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blkio_policy_unregister(&blkio_policy_cfq);
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#endif
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elv_unregister(&iosched_cfq);
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kmem_cache_destroy(cfq_pool);
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}
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@ -35,6 +35,12 @@ struct bsg_job;
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#define BLKDEV_MIN_RQ 4
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#define BLKDEV_MAX_RQ 128 /* Default maximum */
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/*
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* Maximum number of blkcg policies allowed to be registered concurrently.
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* Defined here to simplify include dependency.
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*/
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#define BLKCG_MAX_POLS 2
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struct request;
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typedef void (rq_end_io_fn)(struct request *, int);
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@ -363,7 +369,6 @@ struct request_queue {
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struct list_head icq_list;
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#ifdef CONFIG_BLK_CGROUP
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/* XXX: array size hardcoded to avoid include dependency (temporary) */
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struct list_head blkg_list;
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#endif
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