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 #ifdef CONFIG_BLK_CGROUP
28 enum blkg_rwstat_type
{
35 BLKG_RWSTAT_TOTAL
= BLKG_RWSTAT_NR
,
41 struct cgroup_subsys_state css
;
44 struct radix_tree_root blkg_tree
;
45 struct blkcg_gq
*blkg_hint
;
46 struct hlist_head blkg_list
;
48 struct blkcg_policy_data
*pd
[BLKCG_MAX_POLS
];
50 struct list_head all_blkcgs_node
;
51 #ifdef CONFIG_CGROUP_WRITEBACK
52 struct list_head cgwb_list
;
57 struct u64_stats_sync syncp
;
62 struct u64_stats_sync syncp
;
63 uint64_t cnt
[BLKG_RWSTAT_NR
];
67 * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
68 * request_queue (q). This is used by blkcg policies which need to track
69 * information per blkcg - q pair.
71 * There can be multiple active blkcg policies and each has its private
72 * data on each blkg, the size of which is determined by
73 * blkcg_policy->pd_size. blkcg core allocates and frees such areas
74 * together with blkg and invokes pd_init/exit_fn() methods.
76 * Such private data must embed struct blkg_policy_data (pd) at the
77 * beginning and pd_size can't be smaller than pd.
79 struct blkg_policy_data
{
80 /* the blkg and policy id this per-policy data belongs to */
81 struct blkcg_gq
*blkg
;
84 /* used during policy activation */
85 struct list_head alloc_node
;
89 * Policies that need to keep per-blkcg data which is independent
90 * from any request_queue associated to it must specify its size
91 * with the cpd_size field of the blkcg_policy structure and
92 * embed a blkcg_policy_data in it. cpd_init() is invoked to let
93 * each policy handle per-blkcg data.
95 struct blkcg_policy_data
{
96 /* the policy id this per-policy data belongs to */
100 /* association between a blk cgroup and a request queue */
102 /* Pointer to the associated request_queue */
103 struct request_queue
*q
;
104 struct list_head q_node
;
105 struct hlist_node blkcg_node
;
109 * Each blkg gets congested separately and the congestion state is
110 * propagated to the matching bdi_writeback_congested.
112 struct bdi_writeback_congested
*wb_congested
;
114 /* all non-root blkcg_gq's are guaranteed to have access to parent */
115 struct blkcg_gq
*parent
;
117 /* request allocation list for this blkcg-q pair */
118 struct request_list rl
;
120 /* reference count */
123 /* is this blkg online? protected by both blkcg and q locks */
126 struct blkg_policy_data
*pd
[BLKCG_MAX_POLS
];
128 struct rcu_head rcu_head
;
131 typedef void (blkcg_pol_init_cpd_fn
)(const struct blkcg
*blkcg
);
132 typedef void (blkcg_pol_init_pd_fn
)(struct blkcg_gq
*blkg
);
133 typedef void (blkcg_pol_online_pd_fn
)(struct blkcg_gq
*blkg
);
134 typedef void (blkcg_pol_offline_pd_fn
)(struct blkcg_gq
*blkg
);
135 typedef void (blkcg_pol_exit_pd_fn
)(struct blkcg_gq
*blkg
);
136 typedef void (blkcg_pol_reset_pd_stats_fn
)(struct blkcg_gq
*blkg
);
138 struct blkcg_policy
{
140 /* policy specific private data size */
142 /* policy specific per-blkcg data size */
144 /* cgroup files for the policy */
145 struct cftype
*cftypes
;
148 blkcg_pol_init_cpd_fn
*cpd_init_fn
;
149 blkcg_pol_init_pd_fn
*pd_init_fn
;
150 blkcg_pol_online_pd_fn
*pd_online_fn
;
151 blkcg_pol_offline_pd_fn
*pd_offline_fn
;
152 blkcg_pol_exit_pd_fn
*pd_exit_fn
;
153 blkcg_pol_reset_pd_stats_fn
*pd_reset_stats_fn
;
156 extern struct blkcg blkcg_root
;
157 extern struct cgroup_subsys_state
* const blkcg_root_css
;
159 struct blkcg_gq
*blkg_lookup(struct blkcg
*blkcg
, struct request_queue
*q
);
160 struct blkcg_gq
*blkg_lookup_create(struct blkcg
*blkcg
,
161 struct request_queue
*q
);
162 int blkcg_init_queue(struct request_queue
*q
);
163 void blkcg_drain_queue(struct request_queue
*q
);
164 void blkcg_exit_queue(struct request_queue
*q
);
166 /* Blkio controller policy registration */
167 int blkcg_policy_register(struct blkcg_policy
*pol
);
168 void blkcg_policy_unregister(struct blkcg_policy
*pol
);
169 int blkcg_activate_policy(struct request_queue
*q
,
170 const struct blkcg_policy
*pol
);
171 void blkcg_deactivate_policy(struct request_queue
*q
,
172 const struct blkcg_policy
*pol
);
174 void blkcg_print_blkgs(struct seq_file
*sf
, struct blkcg
*blkcg
,
175 u64 (*prfill
)(struct seq_file
*,
176 struct blkg_policy_data
*, int),
177 const struct blkcg_policy
*pol
, int data
,
179 u64
__blkg_prfill_u64(struct seq_file
*sf
, struct blkg_policy_data
*pd
, u64 v
);
180 u64
__blkg_prfill_rwstat(struct seq_file
*sf
, struct blkg_policy_data
*pd
,
181 const struct blkg_rwstat
*rwstat
);
182 u64
blkg_prfill_stat(struct seq_file
*sf
, struct blkg_policy_data
*pd
, int off
);
183 u64
blkg_prfill_rwstat(struct seq_file
*sf
, struct blkg_policy_data
*pd
,
186 u64
blkg_stat_recursive_sum(struct blkg_policy_data
*pd
, int off
);
187 struct blkg_rwstat
blkg_rwstat_recursive_sum(struct blkg_policy_data
*pd
,
190 struct blkg_conf_ctx
{
191 struct gendisk
*disk
;
192 struct blkcg_gq
*blkg
;
196 int blkg_conf_prep(struct blkcg
*blkcg
, const struct blkcg_policy
*pol
,
197 const char *input
, struct blkg_conf_ctx
*ctx
);
198 void blkg_conf_finish(struct blkg_conf_ctx
*ctx
);
201 static inline struct blkcg
*css_to_blkcg(struct cgroup_subsys_state
*css
)
203 return css
? container_of(css
, struct blkcg
, css
) : NULL
;
206 static inline struct blkcg
*task_blkcg(struct task_struct
*tsk
)
208 return css_to_blkcg(task_css(tsk
, blkio_cgrp_id
));
211 static inline struct blkcg
*bio_blkcg(struct bio
*bio
)
213 if (bio
&& bio
->bi_css
)
214 return css_to_blkcg(bio
->bi_css
);
215 return task_blkcg(current
);
218 static inline struct cgroup_subsys_state
*
219 task_get_blkcg_css(struct task_struct
*task
)
221 return task_get_css(task
, blkio_cgrp_id
);
225 * blkcg_parent - get the parent of a blkcg
226 * @blkcg: blkcg of interest
228 * Return the parent blkcg of @blkcg. Can be called anytime.
230 static inline struct blkcg
*blkcg_parent(struct blkcg
*blkcg
)
232 return css_to_blkcg(blkcg
->css
.parent
);
236 * blkg_to_pdata - get policy private data
237 * @blkg: blkg of interest
238 * @pol: policy of interest
240 * Return pointer to private data associated with the @blkg-@pol pair.
242 static inline struct blkg_policy_data
*blkg_to_pd(struct blkcg_gq
*blkg
,
243 struct blkcg_policy
*pol
)
245 return blkg
? blkg
->pd
[pol
->plid
] : NULL
;
248 static inline struct blkcg_policy_data
*blkcg_to_cpd(struct blkcg
*blkcg
,
249 struct blkcg_policy
*pol
)
251 return blkcg
? blkcg
->pd
[pol
->plid
] : NULL
;
255 * pdata_to_blkg - get blkg associated with policy private data
256 * @pd: policy private data of interest
258 * @pd is policy private data. Determine the blkg it's associated with.
260 static inline struct blkcg_gq
*pd_to_blkg(struct blkg_policy_data
*pd
)
262 return pd
? pd
->blkg
: NULL
;
266 * blkg_path - format cgroup path of blkg
267 * @blkg: blkg of interest
268 * @buf: target buffer
269 * @buflen: target buffer length
271 * Format the path of the cgroup of @blkg into @buf.
273 static inline int blkg_path(struct blkcg_gq
*blkg
, char *buf
, int buflen
)
277 p
= cgroup_path(blkg
->blkcg
->css
.cgroup
, buf
, buflen
);
279 strncpy(buf
, "<unavailable>", buflen
);
280 return -ENAMETOOLONG
;
283 memmove(buf
, p
, buf
+ buflen
- p
);
288 * blkg_get - get a blkg reference
291 * The caller should be holding an existing reference.
293 static inline void blkg_get(struct blkcg_gq
*blkg
)
295 WARN_ON_ONCE(atomic_read(&blkg
->refcnt
) <= 0);
296 atomic_inc(&blkg
->refcnt
);
299 void __blkg_release_rcu(struct rcu_head
*rcu
);
302 * blkg_put - put a blkg reference
305 static inline void blkg_put(struct blkcg_gq
*blkg
)
307 WARN_ON_ONCE(atomic_read(&blkg
->refcnt
) <= 0);
308 if (atomic_dec_and_test(&blkg
->refcnt
))
309 call_rcu(&blkg
->rcu_head
, __blkg_release_rcu
);
312 struct blkcg_gq
*__blkg_lookup(struct blkcg
*blkcg
, struct request_queue
*q
,
316 * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
317 * @d_blkg: loop cursor pointing to the current descendant
318 * @pos_css: used for iteration
319 * @p_blkg: target blkg to walk descendants of
321 * Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU
322 * read locked. If called under either blkcg or queue lock, the iteration
323 * is guaranteed to include all and only online blkgs. The caller may
324 * update @pos_css by calling css_rightmost_descendant() to skip subtree.
325 * @p_blkg is included in the iteration and the first node to be visited.
327 #define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg) \
328 css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css) \
329 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \
330 (p_blkg)->q, false)))
333 * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
334 * @d_blkg: loop cursor pointing to the current descendant
335 * @pos_css: used for iteration
336 * @p_blkg: target blkg to walk descendants of
338 * Similar to blkg_for_each_descendant_pre() but performs post-order
339 * traversal instead. Synchronization rules are the same. @p_blkg is
340 * included in the iteration and the last node to be visited.
342 #define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg) \
343 css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css) \
344 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \
345 (p_blkg)->q, false)))
348 * blk_get_rl - get request_list to use
349 * @q: request_queue of interest
350 * @bio: bio which will be attached to the allocated request (may be %NULL)
352 * The caller wants to allocate a request from @q to use for @bio. Find
353 * the request_list to use and obtain a reference on it. Should be called
354 * under queue_lock. This function is guaranteed to return non-%NULL
357 static inline struct request_list
*blk_get_rl(struct request_queue
*q
,
361 struct blkcg_gq
*blkg
;
365 blkcg
= bio_blkcg(bio
);
367 /* bypass blkg lookup and use @q->root_rl directly for root */
368 if (blkcg
== &blkcg_root
)
372 * Try to use blkg->rl. blkg lookup may fail under memory pressure
373 * or if either the blkcg or queue is going away. Fall back to
374 * root_rl in such cases.
376 blkg
= blkg_lookup_create(blkcg
, q
);
377 if (unlikely(IS_ERR(blkg
)))
389 * blk_put_rl - put request_list
390 * @rl: request_list to put
392 * Put the reference acquired by blk_get_rl(). Should be called under
395 static inline void blk_put_rl(struct request_list
*rl
)
397 /* root_rl may not have blkg set */
398 if (rl
->blkg
&& rl
->blkg
->blkcg
!= &blkcg_root
)
403 * blk_rq_set_rl - associate a request with a request_list
404 * @rq: request of interest
405 * @rl: target request_list
407 * Associate @rq with @rl so that accounting and freeing can know the
408 * request_list @rq came from.
410 static inline void blk_rq_set_rl(struct request
*rq
, struct request_list
*rl
)
416 * blk_rq_rl - return the request_list a request came from
417 * @rq: request of interest
419 * Return the request_list @rq is allocated from.
421 static inline struct request_list
*blk_rq_rl(struct request
*rq
)
426 struct request_list
*__blk_queue_next_rl(struct request_list
*rl
,
427 struct request_queue
*q
);
429 * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
431 * Should be used under queue_lock.
433 #define blk_queue_for_each_rl(rl, q) \
434 for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
436 static inline void blkg_stat_init(struct blkg_stat
*stat
)
438 u64_stats_init(&stat
->syncp
);
442 * blkg_stat_add - add a value to a blkg_stat
443 * @stat: target blkg_stat
446 * Add @val to @stat. The caller is responsible for synchronizing calls to
449 static inline void blkg_stat_add(struct blkg_stat
*stat
, uint64_t val
)
451 u64_stats_update_begin(&stat
->syncp
);
453 u64_stats_update_end(&stat
->syncp
);
457 * blkg_stat_read - read the current value of a blkg_stat
458 * @stat: blkg_stat to read
460 * Read the current value of @stat. This function can be called without
461 * synchroniztion and takes care of u64 atomicity.
463 static inline uint64_t blkg_stat_read(struct blkg_stat
*stat
)
469 start
= u64_stats_fetch_begin_irq(&stat
->syncp
);
471 } while (u64_stats_fetch_retry_irq(&stat
->syncp
, start
));
477 * blkg_stat_reset - reset a blkg_stat
478 * @stat: blkg_stat to reset
480 static inline void blkg_stat_reset(struct blkg_stat
*stat
)
486 * blkg_stat_merge - merge a blkg_stat into another
487 * @to: the destination blkg_stat
490 * Add @from's count to @to.
492 static inline void blkg_stat_merge(struct blkg_stat
*to
, struct blkg_stat
*from
)
494 blkg_stat_add(to
, blkg_stat_read(from
));
497 static inline void blkg_rwstat_init(struct blkg_rwstat
*rwstat
)
499 u64_stats_init(&rwstat
->syncp
);
503 * blkg_rwstat_add - add a value to a blkg_rwstat
504 * @rwstat: target blkg_rwstat
505 * @rw: mask of REQ_{WRITE|SYNC}
508 * Add @val to @rwstat. The counters are chosen according to @rw. The
509 * caller is responsible for synchronizing calls to this function.
511 static inline void blkg_rwstat_add(struct blkg_rwstat
*rwstat
,
512 int rw
, uint64_t val
)
514 u64_stats_update_begin(&rwstat
->syncp
);
517 rwstat
->cnt
[BLKG_RWSTAT_WRITE
] += val
;
519 rwstat
->cnt
[BLKG_RWSTAT_READ
] += val
;
521 rwstat
->cnt
[BLKG_RWSTAT_SYNC
] += val
;
523 rwstat
->cnt
[BLKG_RWSTAT_ASYNC
] += val
;
525 u64_stats_update_end(&rwstat
->syncp
);
529 * blkg_rwstat_read - read the current values of a blkg_rwstat
530 * @rwstat: blkg_rwstat to read
532 * Read the current snapshot of @rwstat and return it as the return value.
533 * This function can be called without synchronization and takes care of
536 static inline struct blkg_rwstat
blkg_rwstat_read(struct blkg_rwstat
*rwstat
)
539 struct blkg_rwstat tmp
;
542 start
= u64_stats_fetch_begin_irq(&rwstat
->syncp
);
544 } while (u64_stats_fetch_retry_irq(&rwstat
->syncp
, start
));
550 * blkg_rwstat_total - read the total count of a blkg_rwstat
551 * @rwstat: blkg_rwstat to read
553 * Return the total count of @rwstat regardless of the IO direction. This
554 * function can be called without synchronization and takes care of u64
557 static inline uint64_t blkg_rwstat_total(struct blkg_rwstat
*rwstat
)
559 struct blkg_rwstat tmp
= blkg_rwstat_read(rwstat
);
561 return tmp
.cnt
[BLKG_RWSTAT_READ
] + tmp
.cnt
[BLKG_RWSTAT_WRITE
];
565 * blkg_rwstat_reset - reset a blkg_rwstat
566 * @rwstat: blkg_rwstat to reset
568 static inline void blkg_rwstat_reset(struct blkg_rwstat
*rwstat
)
570 memset(rwstat
->cnt
, 0, sizeof(rwstat
->cnt
));
574 * blkg_rwstat_merge - merge a blkg_rwstat into another
575 * @to: the destination blkg_rwstat
578 * Add @from's counts to @to.
580 static inline void blkg_rwstat_merge(struct blkg_rwstat
*to
,
581 struct blkg_rwstat
*from
)
583 struct blkg_rwstat v
= blkg_rwstat_read(from
);
586 u64_stats_update_begin(&to
->syncp
);
587 for (i
= 0; i
< BLKG_RWSTAT_NR
; i
++)
588 to
->cnt
[i
] += v
.cnt
[i
];
589 u64_stats_update_end(&to
->syncp
);
592 #else /* CONFIG_BLK_CGROUP */
597 struct blkg_policy_data
{
600 struct blkcg_policy_data
{
606 struct blkcg_policy
{
609 #define blkcg_root_css ((struct cgroup_subsys_state *)ERR_PTR(-EINVAL))
611 static inline struct cgroup_subsys_state
*
612 task_get_blkcg_css(struct task_struct
*task
)
619 static inline struct blkcg_gq
*blkg_lookup(struct blkcg
*blkcg
, void *key
) { return NULL
; }
620 static inline int blkcg_init_queue(struct request_queue
*q
) { return 0; }
621 static inline void blkcg_drain_queue(struct request_queue
*q
) { }
622 static inline void blkcg_exit_queue(struct request_queue
*q
) { }
623 static inline int blkcg_policy_register(struct blkcg_policy
*pol
) { return 0; }
624 static inline void blkcg_policy_unregister(struct blkcg_policy
*pol
) { }
625 static inline int blkcg_activate_policy(struct request_queue
*q
,
626 const struct blkcg_policy
*pol
) { return 0; }
627 static inline void blkcg_deactivate_policy(struct request_queue
*q
,
628 const struct blkcg_policy
*pol
) { }
630 static inline struct blkcg
*bio_blkcg(struct bio
*bio
) { return NULL
; }
632 static inline struct blkg_policy_data
*blkg_to_pd(struct blkcg_gq
*blkg
,
633 struct blkcg_policy
*pol
) { return NULL
; }
634 static inline struct blkcg_gq
*pd_to_blkg(struct blkg_policy_data
*pd
) { return NULL
; }
635 static inline char *blkg_path(struct blkcg_gq
*blkg
) { return NULL
; }
636 static inline void blkg_get(struct blkcg_gq
*blkg
) { }
637 static inline void blkg_put(struct blkcg_gq
*blkg
) { }
639 static inline struct request_list
*blk_get_rl(struct request_queue
*q
,
640 struct bio
*bio
) { return &q
->root_rl
; }
641 static inline void blk_put_rl(struct request_list
*rl
) { }
642 static inline void blk_rq_set_rl(struct request
*rq
, struct request_list
*rl
) { }
643 static inline struct request_list
*blk_rq_rl(struct request
*rq
) { return &rq
->q
->root_rl
; }
645 #define blk_queue_for_each_rl(rl, q) \
646 for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
648 #endif /* CONFIG_BLOCK */
649 #endif /* CONFIG_BLK_CGROUP */
650 #endif /* _BLK_CGROUP_H */