#ifndef _BLK_CGROUP_H #define _BLK_CGROUP_H /* * Common Block IO controller cgroup interface * * Based on ideas and code from CFQ, CFS and BFQ: * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> * * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> * Paolo Valente <paolo.valente@unimore.it> * * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com> * Nauman Rafique <nauman@google.com> */ #include <linux/cgroup.h> #include <linux/u64_stats_sync.h> #include <linux/seq_file.h> #include <linux/radix-tree.h> #include <linux/blkdev.h> /* Max limits for throttle policy */ #define THROTL_IOPS_MAX UINT_MAX /* CFQ specific, out here for blkcg->cfq_weight */ #define CFQ_WEIGHT_MIN 10 #define CFQ_WEIGHT_MAX 1000 #define CFQ_WEIGHT_DEFAULT 500 #ifdef CONFIG_BLK_CGROUP enum blkg_rwstat_type { BLKG_RWSTAT_READ, BLKG_RWSTAT_WRITE, BLKG_RWSTAT_SYNC, BLKG_RWSTAT_ASYNC, BLKG_RWSTAT_NR, BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR, }; struct blkcg_gq; struct blkcg { struct cgroup_subsys_state css; spinlock_t lock; struct radix_tree_root blkg_tree; struct blkcg_gq *blkg_hint; struct hlist_head blkg_list; /* for policies to test whether associated blkcg has changed */ uint64_t id; /* TODO: per-policy storage in blkcg */ unsigned int cfq_weight; /* belongs to cfq */ unsigned int cfq_leaf_weight; }; struct blkg_stat { struct u64_stats_sync syncp; uint64_t cnt; }; struct blkg_rwstat { struct u64_stats_sync syncp; uint64_t cnt[BLKG_RWSTAT_NR]; }; /* * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a * request_queue (q). This is used by blkcg policies which need to track * information per blkcg - q pair. * * There can be multiple active blkcg policies and each has its private * data on each blkg, the size of which is determined by * blkcg_policy->pd_size. blkcg core allocates and frees such areas * together with blkg and invokes pd_init/exit_fn() methods. * * Such private data must embed struct blkg_policy_data (pd) at the * beginning and pd_size can't be smaller than pd. */ struct blkg_policy_data { /* the blkg and policy id this per-policy data belongs to */ struct blkcg_gq *blkg; int plid; /* used during policy activation */ struct list_head alloc_node; }; /* association between a blk cgroup and a request queue */ struct blkcg_gq { /* Pointer to the associated request_queue */ struct request_queue *q; struct list_head q_node; struct hlist_node blkcg_node; struct blkcg *blkcg; /* all non-root blkcg_gq's are guaranteed to have access to parent */ struct blkcg_gq *parent; /* request allocation list for this blkcg-q pair */ struct request_list rl; /* reference count */ int refcnt; /* is this blkg online? protected by both blkcg and q locks */ bool online; struct blkg_policy_data *pd[BLKCG_MAX_POLS]; struct rcu_head rcu_head; }; typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg); typedef void (blkcg_pol_online_pd_fn)(struct blkcg_gq *blkg); typedef void (blkcg_pol_offline_pd_fn)(struct blkcg_gq *blkg); typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg); typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg); struct blkcg_policy { int plid; /* policy specific private data size */ size_t pd_size; /* cgroup files for the policy */ struct cftype *cftypes; /* operations */ blkcg_pol_init_pd_fn *pd_init_fn; blkcg_pol_online_pd_fn *pd_online_fn; blkcg_pol_offline_pd_fn *pd_offline_fn; blkcg_pol_exit_pd_fn *pd_exit_fn; blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn; }; extern struct blkcg blkcg_root; struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q); struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, struct request_queue *q); int blkcg_init_queue(struct request_queue *q); void blkcg_drain_queue(struct request_queue *q); void blkcg_exit_queue(struct request_queue *q); /* Blkio controller policy registration */ int blkcg_policy_register(struct blkcg_policy *pol); void blkcg_policy_unregister(struct blkcg_policy *pol); int blkcg_activate_policy(struct request_queue *q, const struct blkcg_policy *pol); void blkcg_deactivate_policy(struct request_queue *q, const struct blkcg_policy *pol); void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg, u64 (*prfill)(struct seq_file *, struct blkg_policy_data *, int), const struct blkcg_policy *pol, int data, bool show_total); u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v); u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, const struct blkg_rwstat *rwstat); u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off); u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, int off); u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off); struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd, int off); struct blkg_conf_ctx { struct gendisk *disk; struct blkcg_gq *blkg; u64 v; }; int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, const char *input, struct blkg_conf_ctx *ctx); void blkg_conf_finish(struct blkg_conf_ctx *ctx); static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css) { return css ? container_of(css, struct blkcg, css) : NULL; } static inline struct blkcg *task_blkcg(struct task_struct *tsk) { return css_to_blkcg(task_css(tsk, blkio_subsys_id)); } static inline struct blkcg *bio_blkcg(struct bio *bio) { if (bio && bio->bi_css) return css_to_blkcg(bio->bi_css); return task_blkcg(current); } /** * blkcg_parent - get the parent of a blkcg * @blkcg: blkcg of interest * * Return the parent blkcg of @blkcg. Can be called anytime. */ static inline struct blkcg *blkcg_parent(struct blkcg *blkcg) { return css_to_blkcg(css_parent(&blkcg->css)); } /** * blkg_to_pdata - get policy private data * @blkg: blkg of interest * @pol: policy of interest * * Return pointer to private data associated with the @blkg-@pol pair. */ static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg, struct blkcg_policy *pol) { return blkg ? blkg->pd[pol->plid] : NULL; } /** * pdata_to_blkg - get blkg associated with policy private data * @pd: policy private data of interest * * @pd is policy private data. Determine the blkg it's associated with. */ static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return pd ? pd->blkg : NULL; } /** * blkg_path - format cgroup path of blkg * @blkg: blkg of interest * @buf: target buffer * @buflen: target buffer length * * Format the path of the cgroup of @blkg into @buf. */ static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen) { int ret; ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen); if (ret) strncpy(buf, "<unavailable>", buflen); return ret; } /** * blkg_get - get a blkg reference * @blkg: blkg to get * * The caller should be holding queue_lock and an existing reference. */ static inline void blkg_get(struct blkcg_gq *blkg) { lockdep_assert_held(blkg->q->queue_lock); WARN_ON_ONCE(!blkg->refcnt); blkg->refcnt++; } void __blkg_release_rcu(struct rcu_head *rcu); /** * blkg_put - put a blkg reference * @blkg: blkg to put * * The caller should be holding queue_lock. */ static inline void blkg_put(struct blkcg_gq *blkg) { lockdep_assert_held(blkg->q->queue_lock); WARN_ON_ONCE(blkg->refcnt <= 0); if (!--blkg->refcnt) call_rcu(&blkg->rcu_head, __blkg_release_rcu); } struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q, bool update_hint); /** * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants * @d_blkg: loop cursor pointing to the current descendant * @pos_css: used for iteration * @p_blkg: target blkg to walk descendants of * * Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU * read locked. If called under either blkcg or queue lock, the iteration * is guaranteed to include all and only online blkgs. The caller may * update @pos_css by calling css_rightmost_descendant() to skip subtree. * @p_blkg is included in the iteration and the first node to be visited. */ #define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg) \ css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css) \ if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \ (p_blkg)->q, false))) /** * blkg_for_each_descendant_post - post-order walk of a blkg's descendants * @d_blkg: loop cursor pointing to the current descendant * @pos_css: used for iteration * @p_blkg: target blkg to walk descendants of * * Similar to blkg_for_each_descendant_pre() but performs post-order * traversal instead. Synchronization rules are the same. @p_blkg is * included in the iteration and the last node to be visited. */ #define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg) \ css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css) \ if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \ (p_blkg)->q, false))) /** * blk_get_rl - get request_list to use * @q: request_queue of interest * @bio: bio which will be attached to the allocated request (may be %NULL) * * The caller wants to allocate a request from @q to use for @bio. Find * the request_list to use and obtain a reference on it. Should be called * under queue_lock. This function is guaranteed to return non-%NULL * request_list. */ static inline struct request_list *blk_get_rl(struct request_queue *q, struct bio *bio) { struct blkcg *blkcg; struct blkcg_gq *blkg; rcu_read_lock(); blkcg = bio_blkcg(bio); /* bypass blkg lookup and use @q->root_rl directly for root */ if (blkcg == &blkcg_root) goto root_rl; /* * Try to use blkg->rl. blkg lookup may fail under memory pressure * or if either the blkcg or queue is going away. Fall back to * root_rl in such cases. */ blkg = blkg_lookup_create(blkcg, q); if (unlikely(IS_ERR(blkg))) goto root_rl; blkg_get(blkg); rcu_read_unlock(); return &blkg->rl; root_rl: rcu_read_unlock(); return &q->root_rl; } /** * blk_put_rl - put request_list * @rl: request_list to put * * Put the reference acquired by blk_get_rl(). Should be called under * queue_lock. */ static inline void blk_put_rl(struct request_list *rl) { /* root_rl may not have blkg set */ if (rl->blkg && rl->blkg->blkcg != &blkcg_root) blkg_put(rl->blkg); } /** * blk_rq_set_rl - associate a request with a request_list * @rq: request of interest * @rl: target request_list * * Associate @rq with @rl so that accounting and freeing can know the * request_list @rq came from. */ static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { rq->rl = rl; } /** * blk_rq_rl - return the request_list a request came from * @rq: request of interest * * Return the request_list @rq is allocated from. */ static inline struct request_list *blk_rq_rl(struct request *rq) { return rq->rl; } struct request_list *__blk_queue_next_rl(struct request_list *rl, struct request_queue *q); /** * blk_queue_for_each_rl - iterate through all request_lists of a request_queue * * Should be used under queue_lock. */ #define blk_queue_for_each_rl(rl, q) \ for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q))) /** * blkg_stat_add - add a value to a blkg_stat * @stat: target blkg_stat * @val: value to add * * Add @val to @stat. The caller is responsible for synchronizing calls to * this function. */ static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val) { u64_stats_update_begin(&stat->syncp); stat->cnt += val; u64_stats_update_end(&stat->syncp); } /** * blkg_stat_read - read the current value of a blkg_stat * @stat: blkg_stat to read * * Read the current value of @stat. This function can be called without * synchroniztion and takes care of u64 atomicity. */ static inline uint64_t blkg_stat_read(struct blkg_stat *stat) { unsigned int start; uint64_t v; do { start = u64_stats_fetch_begin(&stat->syncp); v = stat->cnt; } while (u64_stats_fetch_retry(&stat->syncp, start)); return v; } /** * blkg_stat_reset - reset a blkg_stat * @stat: blkg_stat to reset */ static inline void blkg_stat_reset(struct blkg_stat *stat) { stat->cnt = 0; } /** * blkg_stat_merge - merge a blkg_stat into another * @to: the destination blkg_stat * @from: the source * * Add @from's count to @to. */ static inline void blkg_stat_merge(struct blkg_stat *to, struct blkg_stat *from) { blkg_stat_add(to, blkg_stat_read(from)); } /** * blkg_rwstat_add - add a value to a blkg_rwstat * @rwstat: target blkg_rwstat * @rw: mask of REQ_{WRITE|SYNC} * @val: value to add * * Add @val to @rwstat. The counters are chosen according to @rw. The * caller is responsible for synchronizing calls to this function. */ static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat, int rw, uint64_t val) { u64_stats_update_begin(&rwstat->syncp); if (rw & REQ_WRITE) rwstat->cnt[BLKG_RWSTAT_WRITE] += val; else rwstat->cnt[BLKG_RWSTAT_READ] += val; if (rw & REQ_SYNC) rwstat->cnt[BLKG_RWSTAT_SYNC] += val; else rwstat->cnt[BLKG_RWSTAT_ASYNC] += val; u64_stats_update_end(&rwstat->syncp); } /** * blkg_rwstat_read - read the current values of a blkg_rwstat * @rwstat: blkg_rwstat to read * * Read the current snapshot of @rwstat and return it as the return value. * This function can be called without synchronization and takes care of * u64 atomicity. */ static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat) { unsigned int start; struct blkg_rwstat tmp; do { start = u64_stats_fetch_begin(&rwstat->syncp); tmp = *rwstat; } while (u64_stats_fetch_retry(&rwstat->syncp, start)); return tmp; } /** * blkg_rwstat_total - read the total count of a blkg_rwstat * @rwstat: blkg_rwstat to read * * Return the total count of @rwstat regardless of the IO direction. This * function can be called without synchronization and takes care of u64 * atomicity. */ static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat) { struct blkg_rwstat tmp = blkg_rwstat_read(rwstat); return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE]; } /** * blkg_rwstat_reset - reset a blkg_rwstat * @rwstat: blkg_rwstat to reset */ static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat) { memset(rwstat->cnt, 0, sizeof(rwstat->cnt)); } /** * blkg_rwstat_merge - merge a blkg_rwstat into another * @to: the destination blkg_rwstat * @from: the source * * Add @from's counts to @to. */ static inline void blkg_rwstat_merge(struct blkg_rwstat *to, struct blkg_rwstat *from) { struct blkg_rwstat v = blkg_rwstat_read(from); int i; u64_stats_update_begin(&to->syncp); for (i = 0; i < BLKG_RWSTAT_NR; i++) to->cnt[i] += v.cnt[i]; u64_stats_update_end(&to->syncp); } #else /* CONFIG_BLK_CGROUP */ struct cgroup; struct blkcg; struct blkg_policy_data { }; struct blkcg_gq { }; struct blkcg_policy { }; static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; } static inline int blkcg_init_queue(struct request_queue *q) { return 0; } static inline void blkcg_drain_queue(struct request_queue *q) { } static inline void blkcg_exit_queue(struct request_queue *q) { } static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; } static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { } static inline int blkcg_activate_policy(struct request_queue *q, const struct blkcg_policy *pol) { return 0; } static inline void blkcg_deactivate_policy(struct request_queue *q, const struct blkcg_policy *pol) { } static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; } static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg, struct blkcg_policy *pol) { return NULL; } static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; } static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; } static inline void blkg_get(struct blkcg_gq *blkg) { } static inline void blkg_put(struct blkcg_gq *blkg) { } static inline struct request_list *blk_get_rl(struct request_queue *q, struct bio *bio) { return &q->root_rl; } static inline void blk_put_rl(struct request_list *rl) { } static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { } static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; } #define blk_queue_for_each_rl(rl, q) \ for ((rl) = &(q)->root_rl; (rl); (rl) = NULL) #endif /* CONFIG_BLK_CGROUP */ #endif /* _BLK_CGROUP_H */