FreeBSD/Linux Kernel Cross Reference
sys/block/blk-cgroup.h

     #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 */
    };
    
    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 this per-policy data belongs to */
            struct blkcg_gq                 *blkg;
    
            /* 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;
            /* request allocation list for this blkcg-q pair */
            struct request_list             rl;
            /* reference count */
           int                             refcnt;
   
           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_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_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);
   
   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 *cgroup_to_blkcg(struct cgroup *cgroup)
   {
           return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
                               struct blkcg, css);
   }
   
   static inline struct blkcg *task_blkcg(struct task_struct *tsk)
   {
           return container_of(task_subsys_state(tsk, blkio_subsys_id),
                               struct blkcg, css);
   }
   
   static inline struct blkcg *bio_blkcg(struct bio *bio)
   {
           if (bio && bio->bi_css)
                   return container_of(bio->bi_css, struct blkcg, css);
           return task_blkcg(current);
   }
   
   /**
    * 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;
   
           rcu_read_lock();
           ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
           rcu_read_unlock();
           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(struct blkcg_gq *blkg);
   
   /**
    * 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)
                   __blkg_release(blkg);
   }
   
   /**
    * 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_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_sum - 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_sum(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));
   }
   
   #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 *cgroup_to_blkcg(struct cgroup *cgroup) { return NULL; }
   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 */

Cache object: 18b2c47130ad610a504847eac493b3a7