4 * Common Block IO controller cgroup interface
6 * Based on ideas and code from CFQ, CFS and BFQ:
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
9 * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
10 * Paolo Valente <paolo.valente@unimore.it>
12 * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
13 * Nauman Rafique <nauman@google.com>
16 #include <linux/cgroup.h>
17 #include <linux/u64_stats_sync.h>
18 #include <linux/seq_file.h>
19 #include <linux/radix-tree.h>
21 /* Max limits for throttle policy */
22 #define THROTL_IOPS_MAX UINT_MAX
24 /* CFQ specific, out here for blkcg->cfq_weight */
25 #define CFQ_WEIGHT_MIN 10
26 #define CFQ_WEIGHT_MAX 1000
27 #define CFQ_WEIGHT_DEFAULT 500
29 #ifdef CONFIG_BLK_CGROUP
31 enum blkg_rwstat_type
{
38 BLKG_RWSTAT_TOTAL
= BLKG_RWSTAT_NR
,
44 struct cgroup_subsys_state css
;
47 struct radix_tree_root blkg_tree
;
48 struct blkcg_gq
*blkg_hint
;
49 struct hlist_head blkg_list
;
51 /* for policies to test whether associated blkcg has changed */
54 /* TODO: per-policy storage in blkcg */
55 unsigned int cfq_weight
; /* belongs to cfq */
59 struct u64_stats_sync syncp
;
64 struct u64_stats_sync syncp
;
65 uint64_t cnt
[BLKG_RWSTAT_NR
];
69 * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
70 * request_queue (q). This is used by blkcg policies which need to track
71 * information per blkcg - q pair.
73 * There can be multiple active blkcg policies and each has its private
74 * data on each blkg, the size of which is determined by
75 * blkcg_policy->pd_size. blkcg core allocates and frees such areas
76 * together with blkg and invokes pd_init/exit_fn() methods.
78 * Such private data must embed struct blkg_policy_data (pd) at the
79 * beginning and pd_size can't be smaller than pd.
81 struct blkg_policy_data
{
82 /* the blkg this per-policy data belongs to */
83 struct blkcg_gq
*blkg
;
85 /* used during policy activation */
86 struct list_head alloc_node
;
89 /* association between a blk cgroup and a request queue */
91 /* Pointer to the associated request_queue */
92 struct request_queue
*q
;
93 struct list_head q_node
;
94 struct hlist_node blkcg_node
;
99 struct blkg_policy_data
*pd
[BLKCG_MAX_POLS
];
101 struct rcu_head rcu_head
;
104 typedef void (blkcg_pol_init_pd_fn
)(struct blkcg_gq
*blkg
);
105 typedef void (blkcg_pol_exit_pd_fn
)(struct blkcg_gq
*blkg
);
106 typedef void (blkcg_pol_reset_pd_stats_fn
)(struct blkcg_gq
*blkg
);
108 struct blkcg_policy
{
110 /* policy specific private data size */
112 /* cgroup files for the policy */
113 struct cftype
*cftypes
;
116 blkcg_pol_init_pd_fn
*pd_init_fn
;
117 blkcg_pol_exit_pd_fn
*pd_exit_fn
;
118 blkcg_pol_reset_pd_stats_fn
*pd_reset_stats_fn
;
121 extern struct blkcg blkcg_root
;
123 struct blkcg_gq
*blkg_lookup(struct blkcg
*blkcg
, struct request_queue
*q
);
124 struct blkcg_gq
*blkg_lookup_create(struct blkcg
*blkcg
,
125 struct request_queue
*q
);
126 int blkcg_init_queue(struct request_queue
*q
);
127 void blkcg_drain_queue(struct request_queue
*q
);
128 void blkcg_exit_queue(struct request_queue
*q
);
130 /* Blkio controller policy registration */
131 int blkcg_policy_register(struct blkcg_policy
*pol
);
132 void blkcg_policy_unregister(struct blkcg_policy
*pol
);
133 int blkcg_activate_policy(struct request_queue
*q
,
134 const struct blkcg_policy
*pol
);
135 void blkcg_deactivate_policy(struct request_queue
*q
,
136 const struct blkcg_policy
*pol
);
138 void blkcg_print_blkgs(struct seq_file
*sf
, struct blkcg
*blkcg
,
139 u64 (*prfill
)(struct seq_file
*,
140 struct blkg_policy_data
*, int),
141 const struct blkcg_policy
*pol
, int data
,
143 u64
__blkg_prfill_u64(struct seq_file
*sf
, struct blkg_policy_data
*pd
, u64 v
);
144 u64
__blkg_prfill_rwstat(struct seq_file
*sf
, struct blkg_policy_data
*pd
,
145 const struct blkg_rwstat
*rwstat
);
146 u64
blkg_prfill_stat(struct seq_file
*sf
, struct blkg_policy_data
*pd
, int off
);
147 u64
blkg_prfill_rwstat(struct seq_file
*sf
, struct blkg_policy_data
*pd
,
150 struct blkg_conf_ctx
{
151 struct gendisk
*disk
;
152 struct blkcg_gq
*blkg
;
156 int blkg_conf_prep(struct blkcg
*blkcg
, const struct blkcg_policy
*pol
,
157 const char *input
, struct blkg_conf_ctx
*ctx
);
158 void blkg_conf_finish(struct blkg_conf_ctx
*ctx
);
161 static inline struct blkcg
*cgroup_to_blkcg(struct cgroup
*cgroup
)
163 return container_of(cgroup_subsys_state(cgroup
, blkio_subsys_id
),
167 static inline struct blkcg
*task_blkcg(struct task_struct
*tsk
)
169 return container_of(task_subsys_state(tsk
, blkio_subsys_id
),
173 static inline struct blkcg
*bio_blkcg(struct bio
*bio
)
175 if (bio
&& bio
->bi_css
)
176 return container_of(bio
->bi_css
, struct blkcg
, css
);
177 return task_blkcg(current
);
181 * blkg_to_pdata - get policy private data
182 * @blkg: blkg of interest
183 * @pol: policy of interest
185 * Return pointer to private data associated with the @blkg-@pol pair.
187 static inline struct blkg_policy_data
*blkg_to_pd(struct blkcg_gq
*blkg
,
188 struct blkcg_policy
*pol
)
190 return blkg
? blkg
->pd
[pol
->plid
] : NULL
;
194 * pdata_to_blkg - get blkg associated with policy private data
195 * @pd: policy private data of interest
197 * @pd is policy private data. Determine the blkg it's associated with.
199 static inline struct blkcg_gq
*pd_to_blkg(struct blkg_policy_data
*pd
)
201 return pd
? pd
->blkg
: NULL
;
205 * blkg_path - format cgroup path of blkg
206 * @blkg: blkg of interest
207 * @buf: target buffer
208 * @buflen: target buffer length
210 * Format the path of the cgroup of @blkg into @buf.
212 static inline int blkg_path(struct blkcg_gq
*blkg
, char *buf
, int buflen
)
217 ret
= cgroup_path(blkg
->blkcg
->css
.cgroup
, buf
, buflen
);
220 strncpy(buf
, "<unavailable>", buflen
);
225 * blkg_get - get a blkg reference
228 * The caller should be holding queue_lock and an existing reference.
230 static inline void blkg_get(struct blkcg_gq
*blkg
)
232 lockdep_assert_held(blkg
->q
->queue_lock
);
233 WARN_ON_ONCE(!blkg
->refcnt
);
237 void __blkg_release(struct blkcg_gq
*blkg
);
240 * blkg_put - put a blkg reference
243 * The caller should be holding queue_lock.
245 static inline void blkg_put(struct blkcg_gq
*blkg
)
247 lockdep_assert_held(blkg
->q
->queue_lock
);
248 WARN_ON_ONCE(blkg
->refcnt
<= 0);
250 __blkg_release(blkg
);
254 * blkg_stat_add - add a value to a blkg_stat
255 * @stat: target blkg_stat
258 * Add @val to @stat. The caller is responsible for synchronizing calls to
261 static inline void blkg_stat_add(struct blkg_stat
*stat
, uint64_t val
)
263 u64_stats_update_begin(&stat
->syncp
);
265 u64_stats_update_end(&stat
->syncp
);
269 * blkg_stat_read - read the current value of a blkg_stat
270 * @stat: blkg_stat to read
272 * Read the current value of @stat. This function can be called without
273 * synchroniztion and takes care of u64 atomicity.
275 static inline uint64_t blkg_stat_read(struct blkg_stat
*stat
)
281 start
= u64_stats_fetch_begin(&stat
->syncp
);
283 } while (u64_stats_fetch_retry(&stat
->syncp
, start
));
289 * blkg_stat_reset - reset a blkg_stat
290 * @stat: blkg_stat to reset
292 static inline void blkg_stat_reset(struct blkg_stat
*stat
)
298 * blkg_rwstat_add - add a value to a blkg_rwstat
299 * @rwstat: target blkg_rwstat
300 * @rw: mask of REQ_{WRITE|SYNC}
303 * Add @val to @rwstat. The counters are chosen according to @rw. The
304 * caller is responsible for synchronizing calls to this function.
306 static inline void blkg_rwstat_add(struct blkg_rwstat
*rwstat
,
307 int rw
, uint64_t val
)
309 u64_stats_update_begin(&rwstat
->syncp
);
312 rwstat
->cnt
[BLKG_RWSTAT_WRITE
] += val
;
314 rwstat
->cnt
[BLKG_RWSTAT_READ
] += val
;
316 rwstat
->cnt
[BLKG_RWSTAT_SYNC
] += val
;
318 rwstat
->cnt
[BLKG_RWSTAT_ASYNC
] += val
;
320 u64_stats_update_end(&rwstat
->syncp
);
324 * blkg_rwstat_read - read the current values of a blkg_rwstat
325 * @rwstat: blkg_rwstat to read
327 * Read the current snapshot of @rwstat and return it as the return value.
328 * This function can be called without synchronization and takes care of
331 static inline struct blkg_rwstat
blkg_rwstat_read(struct blkg_rwstat
*rwstat
)
334 struct blkg_rwstat tmp
;
337 start
= u64_stats_fetch_begin(&rwstat
->syncp
);
339 } while (u64_stats_fetch_retry(&rwstat
->syncp
, start
));
345 * blkg_rwstat_sum - read the total count of a blkg_rwstat
346 * @rwstat: blkg_rwstat to read
348 * Return the total count of @rwstat regardless of the IO direction. This
349 * function can be called without synchronization and takes care of u64
352 static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat
*rwstat
)
354 struct blkg_rwstat tmp
= blkg_rwstat_read(rwstat
);
356 return tmp
.cnt
[BLKG_RWSTAT_READ
] + tmp
.cnt
[BLKG_RWSTAT_WRITE
];
360 * blkg_rwstat_reset - reset a blkg_rwstat
361 * @rwstat: blkg_rwstat to reset
363 static inline void blkg_rwstat_reset(struct blkg_rwstat
*rwstat
)
365 memset(rwstat
->cnt
, 0, sizeof(rwstat
->cnt
));
368 #else /* CONFIG_BLK_CGROUP */
373 struct blkg_policy_data
{
379 struct blkcg_policy
{
382 static inline struct blkcg_gq
*blkg_lookup(struct blkcg
*blkcg
, void *key
) { return NULL
; }
383 static inline int blkcg_init_queue(struct request_queue
*q
) { return 0; }
384 static inline void blkcg_drain_queue(struct request_queue
*q
) { }
385 static inline void blkcg_exit_queue(struct request_queue
*q
) { }
386 static inline int blkcg_policy_register(struct blkcg_policy
*pol
) { return 0; }
387 static inline void blkcg_policy_unregister(struct blkcg_policy
*pol
) { }
388 static inline int blkcg_activate_policy(struct request_queue
*q
,
389 const struct blkcg_policy
*pol
) { return 0; }
390 static inline void blkcg_deactivate_policy(struct request_queue
*q
,
391 const struct blkcg_policy
*pol
) { }
393 static inline struct blkcg
*cgroup_to_blkcg(struct cgroup
*cgroup
) { return NULL
; }
394 static inline struct blkcg
*bio_blkcg(struct bio
*bio
) { return NULL
; }
395 static inline struct blkg_policy_data
*blkg_to_pd(struct blkcg_gq
*blkg
,
396 struct blkcg_policy
*pol
) { return NULL
; }
397 static inline struct blkcg_gq
*pd_to_blkg(struct blkg_policy_data
*pd
) { return NULL
; }
398 static inline char *blkg_path(struct blkcg_gq
*blkg
) { return NULL
; }
399 static inline void blkg_get(struct blkcg_gq
*blkg
) { }
400 static inline void blkg_put(struct blkcg_gq
*blkg
) { }
402 #endif /* CONFIG_BLK_CGROUP */
403 #endif /* _BLK_CGROUP_H */