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>
20 #include <linux/blkdev.h>
21 #include <linux/atomic.h>
23 /* Max limits for throttle policy */
24 #define THROTL_IOPS_MAX UINT_MAX
26 /* CFQ specific, out here for blkcg->cfq_weight */
27 #define CFQ_WEIGHT_MIN 10
28 #define CFQ_WEIGHT_MAX 1000
29 #define CFQ_WEIGHT_DEFAULT 500
31 #ifdef CONFIG_BLK_CGROUP
33 enum blkg_rwstat_type
{
40 BLKG_RWSTAT_TOTAL
= BLKG_RWSTAT_NR
,
46 struct cgroup_subsys_state css
;
49 struct radix_tree_root blkg_tree
;
50 struct blkcg_gq
*blkg_hint
;
51 struct hlist_head blkg_list
;
53 /* for policies to test whether associated blkcg has changed */
56 /* TODO: per-policy storage in blkcg */
57 unsigned int cfq_weight
; /* belongs to cfq */
58 unsigned int cfq_leaf_weight
;
62 struct u64_stats_sync syncp
;
67 struct u64_stats_sync syncp
;
68 uint64_t cnt
[BLKG_RWSTAT_NR
];
72 * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
73 * request_queue (q). This is used by blkcg policies which need to track
74 * information per blkcg - q pair.
76 * There can be multiple active blkcg policies and each has its private
77 * data on each blkg, the size of which is determined by
78 * blkcg_policy->pd_size. blkcg core allocates and frees such areas
79 * together with blkg and invokes pd_init/exit_fn() methods.
81 * Such private data must embed struct blkg_policy_data (pd) at the
82 * beginning and pd_size can't be smaller than pd.
84 struct blkg_policy_data
{
85 /* the blkg and policy id this per-policy data belongs to */
86 struct blkcg_gq
*blkg
;
89 /* used during policy activation */
90 struct list_head alloc_node
;
93 /* association between a blk cgroup and a request queue */
95 /* Pointer to the associated request_queue */
96 struct request_queue
*q
;
97 struct list_head q_node
;
98 struct hlist_node blkcg_node
;
101 /* all non-root blkcg_gq's are guaranteed to have access to parent */
102 struct blkcg_gq
*parent
;
104 /* request allocation list for this blkcg-q pair */
105 struct request_list rl
;
107 /* reference count */
110 /* is this blkg online? protected by both blkcg and q locks */
113 struct blkg_policy_data
*pd
[BLKCG_MAX_POLS
];
115 struct rcu_head rcu_head
;
118 typedef void (blkcg_pol_init_pd_fn
)(struct blkcg_gq
*blkg
);
119 typedef void (blkcg_pol_online_pd_fn
)(struct blkcg_gq
*blkg
);
120 typedef void (blkcg_pol_offline_pd_fn
)(struct blkcg_gq
*blkg
);
121 typedef void (blkcg_pol_exit_pd_fn
)(struct blkcg_gq
*blkg
);
122 typedef void (blkcg_pol_reset_pd_stats_fn
)(struct blkcg_gq
*blkg
);
124 struct blkcg_policy
{
126 /* policy specific private data size */
128 /* cgroup files for the policy */
129 struct cftype
*cftypes
;
132 blkcg_pol_init_pd_fn
*pd_init_fn
;
133 blkcg_pol_online_pd_fn
*pd_online_fn
;
134 blkcg_pol_offline_pd_fn
*pd_offline_fn
;
135 blkcg_pol_exit_pd_fn
*pd_exit_fn
;
136 blkcg_pol_reset_pd_stats_fn
*pd_reset_stats_fn
;
139 extern struct blkcg blkcg_root
;
141 struct blkcg_gq
*blkg_lookup(struct blkcg
*blkcg
, struct request_queue
*q
);
142 struct blkcg_gq
*blkg_lookup_create(struct blkcg
*blkcg
,
143 struct request_queue
*q
);
144 int blkcg_init_queue(struct request_queue
*q
);
145 void blkcg_drain_queue(struct request_queue
*q
);
146 void blkcg_exit_queue(struct request_queue
*q
);
148 /* Blkio controller policy registration */
149 int blkcg_policy_register(struct blkcg_policy
*pol
);
150 void blkcg_policy_unregister(struct blkcg_policy
*pol
);
151 int blkcg_activate_policy(struct request_queue
*q
,
152 const struct blkcg_policy
*pol
);
153 void blkcg_deactivate_policy(struct request_queue
*q
,
154 const struct blkcg_policy
*pol
);
156 void blkcg_print_blkgs(struct seq_file
*sf
, struct blkcg
*blkcg
,
157 u64 (*prfill
)(struct seq_file
*,
158 struct blkg_policy_data
*, int),
159 const struct blkcg_policy
*pol
, int data
,
161 u64
__blkg_prfill_u64(struct seq_file
*sf
, struct blkg_policy_data
*pd
, u64 v
);
162 u64
__blkg_prfill_rwstat(struct seq_file
*sf
, struct blkg_policy_data
*pd
,
163 const struct blkg_rwstat
*rwstat
);
164 u64
blkg_prfill_stat(struct seq_file
*sf
, struct blkg_policy_data
*pd
, int off
);
165 u64
blkg_prfill_rwstat(struct seq_file
*sf
, struct blkg_policy_data
*pd
,
168 u64
blkg_stat_recursive_sum(struct blkg_policy_data
*pd
, int off
);
169 struct blkg_rwstat
blkg_rwstat_recursive_sum(struct blkg_policy_data
*pd
,
172 struct blkg_conf_ctx
{
173 struct gendisk
*disk
;
174 struct blkcg_gq
*blkg
;
178 int blkg_conf_prep(struct blkcg
*blkcg
, const struct blkcg_policy
*pol
,
179 const char *input
, struct blkg_conf_ctx
*ctx
);
180 void blkg_conf_finish(struct blkg_conf_ctx
*ctx
);
183 static inline struct blkcg
*css_to_blkcg(struct cgroup_subsys_state
*css
)
185 return css
? container_of(css
, struct blkcg
, css
) : NULL
;
188 static inline struct blkcg
*task_blkcg(struct task_struct
*tsk
)
190 return css_to_blkcg(task_css(tsk
, blkio_subsys_id
));
193 static inline struct blkcg
*bio_blkcg(struct bio
*bio
)
195 if (bio
&& bio
->bi_css
)
196 return css_to_blkcg(bio
->bi_css
);
197 return task_blkcg(current
);
201 * blkcg_parent - get the parent of a blkcg
202 * @blkcg: blkcg of interest
204 * Return the parent blkcg of @blkcg. Can be called anytime.
206 static inline struct blkcg
*blkcg_parent(struct blkcg
*blkcg
)
208 return css_to_blkcg(css_parent(&blkcg
->css
));
212 * blkg_to_pdata - get policy private data
213 * @blkg: blkg of interest
214 * @pol: policy of interest
216 * Return pointer to private data associated with the @blkg-@pol pair.
218 static inline struct blkg_policy_data
*blkg_to_pd(struct blkcg_gq
*blkg
,
219 struct blkcg_policy
*pol
)
221 return blkg
? blkg
->pd
[pol
->plid
] : NULL
;
225 * pdata_to_blkg - get blkg associated with policy private data
226 * @pd: policy private data of interest
228 * @pd is policy private data. Determine the blkg it's associated with.
230 static inline struct blkcg_gq
*pd_to_blkg(struct blkg_policy_data
*pd
)
232 return pd
? pd
->blkg
: NULL
;
236 * blkg_path - format cgroup path of blkg
237 * @blkg: blkg of interest
238 * @buf: target buffer
239 * @buflen: target buffer length
241 * Format the path of the cgroup of @blkg into @buf.
243 static inline int blkg_path(struct blkcg_gq
*blkg
, char *buf
, int buflen
)
247 ret
= cgroup_path(blkg
->blkcg
->css
.cgroup
, buf
, buflen
);
249 strncpy(buf
, "<unavailable>", buflen
);
254 * blkg_get - get a blkg reference
257 * The caller should be holding an existing reference.
259 static inline void blkg_get(struct blkcg_gq
*blkg
)
261 WARN_ON_ONCE(atomic_read(&blkg
->refcnt
) <= 0);
262 atomic_inc(&blkg
->refcnt
);
265 void __blkg_release_rcu(struct rcu_head
*rcu
);
268 * blkg_put - put a blkg reference
271 static inline void blkg_put(struct blkcg_gq
*blkg
)
273 WARN_ON_ONCE(atomic_read(&blkg
->refcnt
) <= 0);
274 if (atomic_dec_and_test(&blkg
->refcnt
))
275 call_rcu(&blkg
->rcu_head
, __blkg_release_rcu
);
278 struct blkcg_gq
*__blkg_lookup(struct blkcg
*blkcg
, struct request_queue
*q
,
282 * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
283 * @d_blkg: loop cursor pointing to the current descendant
284 * @pos_css: used for iteration
285 * @p_blkg: target blkg to walk descendants of
287 * Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU
288 * read locked. If called under either blkcg or queue lock, the iteration
289 * is guaranteed to include all and only online blkgs. The caller may
290 * update @pos_css by calling css_rightmost_descendant() to skip subtree.
291 * @p_blkg is included in the iteration and the first node to be visited.
293 #define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg) \
294 css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css) \
295 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \
296 (p_blkg)->q, false)))
299 * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
300 * @d_blkg: loop cursor pointing to the current descendant
301 * @pos_css: used for iteration
302 * @p_blkg: target blkg to walk descendants of
304 * Similar to blkg_for_each_descendant_pre() but performs post-order
305 * traversal instead. Synchronization rules are the same. @p_blkg is
306 * included in the iteration and the last node to be visited.
308 #define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg) \
309 css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css) \
310 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \
311 (p_blkg)->q, false)))
314 * blk_get_rl - get request_list to use
315 * @q: request_queue of interest
316 * @bio: bio which will be attached to the allocated request (may be %NULL)
318 * The caller wants to allocate a request from @q to use for @bio. Find
319 * the request_list to use and obtain a reference on it. Should be called
320 * under queue_lock. This function is guaranteed to return non-%NULL
323 static inline struct request_list
*blk_get_rl(struct request_queue
*q
,
327 struct blkcg_gq
*blkg
;
331 blkcg
= bio_blkcg(bio
);
333 /* bypass blkg lookup and use @q->root_rl directly for root */
334 if (blkcg
== &blkcg_root
)
338 * Try to use blkg->rl. blkg lookup may fail under memory pressure
339 * or if either the blkcg or queue is going away. Fall back to
340 * root_rl in such cases.
342 blkg
= blkg_lookup_create(blkcg
, q
);
343 if (unlikely(IS_ERR(blkg
)))
355 * blk_put_rl - put request_list
356 * @rl: request_list to put
358 * Put the reference acquired by blk_get_rl(). Should be called under
361 static inline void blk_put_rl(struct request_list
*rl
)
363 /* root_rl may not have blkg set */
364 if (rl
->blkg
&& rl
->blkg
->blkcg
!= &blkcg_root
)
369 * blk_rq_set_rl - associate a request with a request_list
370 * @rq: request of interest
371 * @rl: target request_list
373 * Associate @rq with @rl so that accounting and freeing can know the
374 * request_list @rq came from.
376 static inline void blk_rq_set_rl(struct request
*rq
, struct request_list
*rl
)
382 * blk_rq_rl - return the request_list a request came from
383 * @rq: request of interest
385 * Return the request_list @rq is allocated from.
387 static inline struct request_list
*blk_rq_rl(struct request
*rq
)
392 struct request_list
*__blk_queue_next_rl(struct request_list
*rl
,
393 struct request_queue
*q
);
395 * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
397 * Should be used under queue_lock.
399 #define blk_queue_for_each_rl(rl, q) \
400 for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
403 * blkg_stat_add - add a value to a blkg_stat
404 * @stat: target blkg_stat
407 * Add @val to @stat. The caller is responsible for synchronizing calls to
410 static inline void blkg_stat_add(struct blkg_stat
*stat
, uint64_t val
)
412 u64_stats_update_begin(&stat
->syncp
);
414 u64_stats_update_end(&stat
->syncp
);
418 * blkg_stat_read - read the current value of a blkg_stat
419 * @stat: blkg_stat to read
421 * Read the current value of @stat. This function can be called without
422 * synchroniztion and takes care of u64 atomicity.
424 static inline uint64_t blkg_stat_read(struct blkg_stat
*stat
)
430 start
= u64_stats_fetch_begin_bh(&stat
->syncp
);
432 } while (u64_stats_fetch_retry_bh(&stat
->syncp
, start
));
438 * blkg_stat_reset - reset a blkg_stat
439 * @stat: blkg_stat to reset
441 static inline void blkg_stat_reset(struct blkg_stat
*stat
)
447 * blkg_stat_merge - merge a blkg_stat into another
448 * @to: the destination blkg_stat
451 * Add @from's count to @to.
453 static inline void blkg_stat_merge(struct blkg_stat
*to
, struct blkg_stat
*from
)
455 blkg_stat_add(to
, blkg_stat_read(from
));
459 * blkg_rwstat_add - add a value to a blkg_rwstat
460 * @rwstat: target blkg_rwstat
461 * @rw: mask of REQ_{WRITE|SYNC}
464 * Add @val to @rwstat. The counters are chosen according to @rw. The
465 * caller is responsible for synchronizing calls to this function.
467 static inline void blkg_rwstat_add(struct blkg_rwstat
*rwstat
,
468 int rw
, uint64_t val
)
470 u64_stats_update_begin(&rwstat
->syncp
);
473 rwstat
->cnt
[BLKG_RWSTAT_WRITE
] += val
;
475 rwstat
->cnt
[BLKG_RWSTAT_READ
] += val
;
477 rwstat
->cnt
[BLKG_RWSTAT_SYNC
] += val
;
479 rwstat
->cnt
[BLKG_RWSTAT_ASYNC
] += val
;
481 u64_stats_update_end(&rwstat
->syncp
);
485 * blkg_rwstat_read - read the current values of a blkg_rwstat
486 * @rwstat: blkg_rwstat to read
488 * Read the current snapshot of @rwstat and return it as the return value.
489 * This function can be called without synchronization and takes care of
492 static inline struct blkg_rwstat
blkg_rwstat_read(struct blkg_rwstat
*rwstat
)
495 struct blkg_rwstat tmp
;
498 start
= u64_stats_fetch_begin_bh(&rwstat
->syncp
);
500 } while (u64_stats_fetch_retry_bh(&rwstat
->syncp
, start
));
506 * blkg_rwstat_total - read the total count of a blkg_rwstat
507 * @rwstat: blkg_rwstat to read
509 * Return the total count of @rwstat regardless of the IO direction. This
510 * function can be called without synchronization and takes care of u64
513 static inline uint64_t blkg_rwstat_total(struct blkg_rwstat
*rwstat
)
515 struct blkg_rwstat tmp
= blkg_rwstat_read(rwstat
);
517 return tmp
.cnt
[BLKG_RWSTAT_READ
] + tmp
.cnt
[BLKG_RWSTAT_WRITE
];
521 * blkg_rwstat_reset - reset a blkg_rwstat
522 * @rwstat: blkg_rwstat to reset
524 static inline void blkg_rwstat_reset(struct blkg_rwstat
*rwstat
)
526 memset(rwstat
->cnt
, 0, sizeof(rwstat
->cnt
));
530 * blkg_rwstat_merge - merge a blkg_rwstat into another
531 * @to: the destination blkg_rwstat
534 * Add @from's counts to @to.
536 static inline void blkg_rwstat_merge(struct blkg_rwstat
*to
,
537 struct blkg_rwstat
*from
)
539 struct blkg_rwstat v
= blkg_rwstat_read(from
);
542 u64_stats_update_begin(&to
->syncp
);
543 for (i
= 0; i
< BLKG_RWSTAT_NR
; i
++)
544 to
->cnt
[i
] += v
.cnt
[i
];
545 u64_stats_update_end(&to
->syncp
);
548 #else /* CONFIG_BLK_CGROUP */
553 struct blkg_policy_data
{
559 struct blkcg_policy
{
562 static inline struct blkcg_gq
*blkg_lookup(struct blkcg
*blkcg
, void *key
) { return NULL
; }
563 static inline int blkcg_init_queue(struct request_queue
*q
) { return 0; }
564 static inline void blkcg_drain_queue(struct request_queue
*q
) { }
565 static inline void blkcg_exit_queue(struct request_queue
*q
) { }
566 static inline int blkcg_policy_register(struct blkcg_policy
*pol
) { return 0; }
567 static inline void blkcg_policy_unregister(struct blkcg_policy
*pol
) { }
568 static inline int blkcg_activate_policy(struct request_queue
*q
,
569 const struct blkcg_policy
*pol
) { return 0; }
570 static inline void blkcg_deactivate_policy(struct request_queue
*q
,
571 const struct blkcg_policy
*pol
) { }
573 static inline struct blkcg
*bio_blkcg(struct bio
*bio
) { return NULL
; }
575 static inline struct blkg_policy_data
*blkg_to_pd(struct blkcg_gq
*blkg
,
576 struct blkcg_policy
*pol
) { return NULL
; }
577 static inline struct blkcg_gq
*pd_to_blkg(struct blkg_policy_data
*pd
) { return NULL
; }
578 static inline char *blkg_path(struct blkcg_gq
*blkg
) { return NULL
; }
579 static inline void blkg_get(struct blkcg_gq
*blkg
) { }
580 static inline void blkg_put(struct blkcg_gq
*blkg
) { }
582 static inline struct request_list
*blk_get_rl(struct request_queue
*q
,
583 struct bio
*bio
) { return &q
->root_rl
; }
584 static inline void blk_put_rl(struct request_list
*rl
) { }
585 static inline void blk_rq_set_rl(struct request
*rq
, struct request_list
*rl
) { }
586 static inline struct request_list
*blk_rq_rl(struct request
*rq
) { return &rq
->q
->root_rl
; }
588 #define blk_queue_for_each_rl(rl, q) \
589 for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
591 #endif /* CONFIG_BLK_CGROUP */
592 #endif /* _BLK_CGROUP_H */