1 /* SPDX-License-Identifier: GPL-2.0 */
5 * Common Block IO controller cgroup interface
7 * Based on ideas and code from CFQ, CFS and BFQ:
8 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
10 * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
11 * Paolo Valente <paolo.valente@unimore.it>
13 * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
14 * Nauman Rafique <nauman@google.com>
17 #include <linux/cgroup.h>
18 #include <linux/percpu_counter.h>
19 #include <linux/seq_file.h>
20 #include <linux/radix-tree.h>
21 #include <linux/blkdev.h>
22 #include <linux/atomic.h>
23 #include <linux/kthread.h>
26 /* percpu_counter batch for blkg_[rw]stats, per-cpu drift doesn't matter */
27 #define BLKG_STAT_CPU_BATCH (INT_MAX / 2)
29 /* Max limits for throttle policy */
30 #define THROTL_IOPS_MAX UINT_MAX
32 #ifdef CONFIG_BLK_CGROUP
34 enum blkg_rwstat_type {
42 BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
48 struct cgroup_subsys_state css;
51 struct radix_tree_root blkg_tree;
52 struct blkcg_gq __rcu *blkg_hint;
53 struct hlist_head blkg_list;
55 struct blkcg_policy_data *cpd[BLKCG_MAX_POLS];
57 struct list_head all_blkcgs_node;
58 #ifdef CONFIG_CGROUP_WRITEBACK
59 struct list_head cgwb_list;
60 refcount_t cgwb_refcnt;
65 * blkg_[rw]stat->aux_cnt is excluded for local stats but included for
66 * recursive. Used to carry stats of dead children.
69 struct percpu_counter cpu_cnt[BLKG_RWSTAT_NR];
70 atomic64_t aux_cnt[BLKG_RWSTAT_NR];
73 struct blkg_rwstat_sample {
74 u64 cnt[BLKG_RWSTAT_NR];
78 * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
79 * request_queue (q). This is used by blkcg policies which need to track
80 * information per blkcg - q pair.
82 * There can be multiple active blkcg policies and each blkg:policy pair is
83 * represented by a blkg_policy_data which is allocated and freed by each
84 * policy's pd_alloc/free_fn() methods. A policy can allocate private data
85 * area by allocating larger data structure which embeds blkg_policy_data
88 struct blkg_policy_data {
89 /* the blkg and policy id this per-policy data belongs to */
90 struct blkcg_gq *blkg;
95 * Policies that need to keep per-blkcg data which is independent from any
96 * request_queue associated to it should implement cpd_alloc/free_fn()
97 * methods. A policy can allocate private data area by allocating larger
98 * data structure which embeds blkcg_policy_data at the beginning.
99 * cpd_init() is invoked to let each policy handle per-blkcg data.
101 struct blkcg_policy_data {
102 /* the blkcg and policy id this per-policy data belongs to */
107 /* association between a blk cgroup and a request queue */
109 /* Pointer to the associated request_queue */
110 struct request_queue *q;
111 struct list_head q_node;
112 struct hlist_node blkcg_node;
116 * Each blkg gets congested separately and the congestion state is
117 * propagated to the matching bdi_writeback_congested.
119 struct bdi_writeback_congested *wb_congested;
121 /* all non-root blkcg_gq's are guaranteed to have access to parent */
122 struct blkcg_gq *parent;
124 /* reference count */
125 struct percpu_ref refcnt;
127 /* is this blkg online? protected by both blkcg and q locks */
130 struct blkg_rwstat stat_bytes;
131 struct blkg_rwstat stat_ios;
133 struct blkg_policy_data *pd[BLKCG_MAX_POLS];
135 spinlock_t async_bio_lock;
136 struct bio_list async_bios;
137 struct work_struct async_bio_work;
140 atomic64_t delay_nsec;
141 atomic64_t delay_start;
145 struct rcu_head rcu_head;
148 typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp);
149 typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd);
150 typedef void (blkcg_pol_free_cpd_fn)(struct blkcg_policy_data *cpd);
151 typedef void (blkcg_pol_bind_cpd_fn)(struct blkcg_policy_data *cpd);
152 typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(gfp_t gfp,
153 struct request_queue *q, struct blkcg *blkcg);
154 typedef void (blkcg_pol_init_pd_fn)(struct blkg_policy_data *pd);
155 typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd);
156 typedef void (blkcg_pol_offline_pd_fn)(struct blkg_policy_data *pd);
157 typedef void (blkcg_pol_free_pd_fn)(struct blkg_policy_data *pd);
158 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd);
159 typedef size_t (blkcg_pol_stat_pd_fn)(struct blkg_policy_data *pd, char *buf,
162 struct blkcg_policy {
164 /* cgroup files for the policy */
165 struct cftype *dfl_cftypes;
166 struct cftype *legacy_cftypes;
169 blkcg_pol_alloc_cpd_fn *cpd_alloc_fn;
170 blkcg_pol_init_cpd_fn *cpd_init_fn;
171 blkcg_pol_free_cpd_fn *cpd_free_fn;
172 blkcg_pol_bind_cpd_fn *cpd_bind_fn;
174 blkcg_pol_alloc_pd_fn *pd_alloc_fn;
175 blkcg_pol_init_pd_fn *pd_init_fn;
176 blkcg_pol_online_pd_fn *pd_online_fn;
177 blkcg_pol_offline_pd_fn *pd_offline_fn;
178 blkcg_pol_free_pd_fn *pd_free_fn;
179 blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn;
180 blkcg_pol_stat_pd_fn *pd_stat_fn;
183 extern struct blkcg blkcg_root;
184 extern struct cgroup_subsys_state * const blkcg_root_css;
185 extern bool blkcg_debug_stats;
187 struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg,
188 struct request_queue *q, bool update_hint);
189 struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
190 struct request_queue *q);
191 struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
192 struct request_queue *q);
193 int blkcg_init_queue(struct request_queue *q);
194 void blkcg_drain_queue(struct request_queue *q);
195 void blkcg_exit_queue(struct request_queue *q);
197 /* Blkio controller policy registration */
198 int blkcg_policy_register(struct blkcg_policy *pol);
199 void blkcg_policy_unregister(struct blkcg_policy *pol);
200 int blkcg_activate_policy(struct request_queue *q,
201 const struct blkcg_policy *pol);
202 void blkcg_deactivate_policy(struct request_queue *q,
203 const struct blkcg_policy *pol);
205 static inline u64 blkg_rwstat_read_counter(struct blkg_rwstat *rwstat,
208 return atomic64_read(&rwstat->aux_cnt[idx]) +
209 percpu_counter_sum_positive(&rwstat->cpu_cnt[idx]);
212 const char *blkg_dev_name(struct blkcg_gq *blkg);
213 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
214 u64 (*prfill)(struct seq_file *,
215 struct blkg_policy_data *, int),
216 const struct blkcg_policy *pol, int data,
218 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
219 u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
220 const struct blkg_rwstat_sample *rwstat);
221 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
223 int blkg_print_stat_bytes(struct seq_file *sf, void *v);
224 int blkg_print_stat_ios(struct seq_file *sf, void *v);
225 int blkg_print_stat_bytes_recursive(struct seq_file *sf, void *v);
226 int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v);
228 void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol,
229 int off, struct blkg_rwstat_sample *sum);
231 struct blkg_conf_ctx {
232 struct gendisk *disk;
233 struct blkcg_gq *blkg;
237 struct gendisk *blkcg_conf_get_disk(char **inputp);
238 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
239 char *input, struct blkg_conf_ctx *ctx);
240 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
243 * blkcg_css - find the current css
245 * Find the css associated with either the kthread or the current task.
246 * This may return a dying css, so it is up to the caller to use tryget logic
247 * to confirm it is alive and well.
249 static inline struct cgroup_subsys_state *blkcg_css(void)
251 struct cgroup_subsys_state *css;
253 css = kthread_blkcg();
256 return task_css(current, io_cgrp_id);
259 static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
261 return css ? container_of(css, struct blkcg, css) : NULL;
265 * __bio_blkcg - internal, inconsistent version to get blkcg
268 * This function is inconsistent and consequently is dangerous to use. The
269 * first part of the function returns a blkcg where a reference is owned by the
270 * bio. This means it does not need to be rcu protected as it cannot go away
271 * with the bio owning a reference to it. However, the latter potentially gets
272 * it from task_css(). This can race against task migration and the cgroup
273 * dying. It is also semantically different as it must be called rcu protected
274 * and is susceptible to failure when trying to get a reference to it.
275 * Therefore, it is not ok to assume that *_get() will always succeed on the
276 * blkcg returned here.
278 static inline struct blkcg *__bio_blkcg(struct bio *bio)
280 if (bio && bio->bi_blkg)
281 return bio->bi_blkg->blkcg;
282 return css_to_blkcg(blkcg_css());
286 * bio_blkcg - grab the blkcg associated with a bio
289 * This returns the blkcg associated with a bio, %NULL if not associated.
290 * Callers are expected to either handle %NULL or know association has been
291 * done prior to calling this.
293 static inline struct blkcg *bio_blkcg(struct bio *bio)
295 if (bio && bio->bi_blkg)
296 return bio->bi_blkg->blkcg;
300 static inline bool blk_cgroup_congested(void)
302 struct cgroup_subsys_state *css;
306 css = kthread_blkcg();
308 css = task_css(current, io_cgrp_id);
310 if (atomic_read(&css->cgroup->congestion_count)) {
321 * bio_issue_as_root_blkg - see if this bio needs to be issued as root blkg
322 * @return: true if this bio needs to be submitted with the root blkg context.
324 * In order to avoid priority inversions we sometimes need to issue a bio as if
325 * it were attached to the root blkg, and then backcharge to the actual owning
326 * blkg. The idea is we do bio_blkcg() to look up the actual context for the
327 * bio and attach the appropriate blkg to the bio. Then we call this helper and
328 * if it is true run with the root blkg for that queue and then do any
329 * backcharging to the originating cgroup once the io is complete.
331 static inline bool bio_issue_as_root_blkg(struct bio *bio)
333 return (bio->bi_opf & (REQ_META | REQ_SWAP)) != 0;
337 * blkcg_parent - get the parent of a blkcg
338 * @blkcg: blkcg of interest
340 * Return the parent blkcg of @blkcg. Can be called anytime.
342 static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
344 return css_to_blkcg(blkcg->css.parent);
348 * __blkg_lookup - internal version of blkg_lookup()
349 * @blkcg: blkcg of interest
350 * @q: request_queue of interest
351 * @update_hint: whether to update lookup hint with the result or not
353 * This is internal version and shouldn't be used by policy
354 * implementations. Looks up blkgs for the @blkcg - @q pair regardless of
355 * @q's bypass state. If @update_hint is %true, the caller should be
356 * holding @q->queue_lock and lookup hint is updated on success.
358 static inline struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg,
359 struct request_queue *q,
362 struct blkcg_gq *blkg;
364 if (blkcg == &blkcg_root)
367 blkg = rcu_dereference(blkcg->blkg_hint);
368 if (blkg && blkg->q == q)
371 return blkg_lookup_slowpath(blkcg, q, update_hint);
375 * blkg_lookup - lookup blkg for the specified blkcg - q pair
376 * @blkcg: blkcg of interest
377 * @q: request_queue of interest
379 * Lookup blkg for the @blkcg - @q pair. This function should be called
380 * under RCU read lock.
382 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg,
383 struct request_queue *q)
385 WARN_ON_ONCE(!rcu_read_lock_held());
386 return __blkg_lookup(blkcg, q, false);
390 * blk_queue_root_blkg - return blkg for the (blkcg_root, @q) pair
391 * @q: request_queue of interest
393 * Lookup blkg for @q at the root level. See also blkg_lookup().
395 static inline struct blkcg_gq *blk_queue_root_blkg(struct request_queue *q)
401 * blkg_to_pdata - get policy private data
402 * @blkg: blkg of interest
403 * @pol: policy of interest
405 * Return pointer to private data associated with the @blkg-@pol pair.
407 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
408 struct blkcg_policy *pol)
410 return blkg ? blkg->pd[pol->plid] : NULL;
413 static inline struct blkcg_policy_data *blkcg_to_cpd(struct blkcg *blkcg,
414 struct blkcg_policy *pol)
416 return blkcg ? blkcg->cpd[pol->plid] : NULL;
420 * pdata_to_blkg - get blkg associated with policy private data
421 * @pd: policy private data of interest
423 * @pd is policy private data. Determine the blkg it's associated with.
425 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
427 return pd ? pd->blkg : NULL;
430 static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd)
432 return cpd ? cpd->blkcg : NULL;
435 extern void blkcg_destroy_blkgs(struct blkcg *blkcg);
437 #ifdef CONFIG_CGROUP_WRITEBACK
440 * blkcg_cgwb_get - get a reference for blkcg->cgwb_list
441 * @blkcg: blkcg of interest
443 * This is used to track the number of active wb's related to a blkcg.
445 static inline void blkcg_cgwb_get(struct blkcg *blkcg)
447 refcount_inc(&blkcg->cgwb_refcnt);
451 * blkcg_cgwb_put - put a reference for @blkcg->cgwb_list
452 * @blkcg: blkcg of interest
454 * This is used to track the number of active wb's related to a blkcg.
455 * When this count goes to zero, all active wb has finished so the
456 * blkcg can continue destruction by calling blkcg_destroy_blkgs().
457 * This work may occur in cgwb_release_workfn() on the cgwb_release
460 static inline void blkcg_cgwb_put(struct blkcg *blkcg)
462 if (refcount_dec_and_test(&blkcg->cgwb_refcnt))
463 blkcg_destroy_blkgs(blkcg);
468 static inline void blkcg_cgwb_get(struct blkcg *blkcg) { }
470 static inline void blkcg_cgwb_put(struct blkcg *blkcg)
472 /* wb isn't being accounted, so trigger destruction right away */
473 blkcg_destroy_blkgs(blkcg);
479 * blkg_path - format cgroup path of blkg
480 * @blkg: blkg of interest
481 * @buf: target buffer
482 * @buflen: target buffer length
484 * Format the path of the cgroup of @blkg into @buf.
486 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
488 return cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
492 * blkg_get - get a blkg reference
495 * The caller should be holding an existing reference.
497 static inline void blkg_get(struct blkcg_gq *blkg)
499 percpu_ref_get(&blkg->refcnt);
503 * blkg_tryget - try and get a blkg reference
506 * This is for use when doing an RCU lookup of the blkg. We may be in the midst
507 * of freeing this blkg, so we can only use it if the refcnt is not zero.
509 static inline bool blkg_tryget(struct blkcg_gq *blkg)
511 return blkg && percpu_ref_tryget(&blkg->refcnt);
515 * blkg_tryget_closest - try and get a blkg ref on the closet blkg
518 * This needs to be called rcu protected. As the failure mode here is to walk
519 * up the blkg tree, this ensure that the blkg->parent pointers are always
520 * valid. This returns the blkg that it ended up taking a reference on or %NULL
521 * if no reference was taken.
523 static inline struct blkcg_gq *blkg_tryget_closest(struct blkcg_gq *blkg)
525 struct blkcg_gq *ret_blkg = NULL;
527 WARN_ON_ONCE(!rcu_read_lock_held());
530 if (blkg_tryget(blkg)) {
541 * blkg_put - put a blkg reference
544 static inline void blkg_put(struct blkcg_gq *blkg)
546 percpu_ref_put(&blkg->refcnt);
550 * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
551 * @d_blkg: loop cursor pointing to the current descendant
552 * @pos_css: used for iteration
553 * @p_blkg: target blkg to walk descendants of
555 * Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU
556 * read locked. If called under either blkcg or queue lock, the iteration
557 * is guaranteed to include all and only online blkgs. The caller may
558 * update @pos_css by calling css_rightmost_descendant() to skip subtree.
559 * @p_blkg is included in the iteration and the first node to be visited.
561 #define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg) \
562 css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css) \
563 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \
564 (p_blkg)->q, false)))
567 * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
568 * @d_blkg: loop cursor pointing to the current descendant
569 * @pos_css: used for iteration
570 * @p_blkg: target blkg to walk descendants of
572 * Similar to blkg_for_each_descendant_pre() but performs post-order
573 * traversal instead. Synchronization rules are the same. @p_blkg is
574 * included in the iteration and the last node to be visited.
576 #define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg) \
577 css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css) \
578 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \
579 (p_blkg)->q, false)))
581 static inline int blkg_rwstat_init(struct blkg_rwstat *rwstat, gfp_t gfp)
585 for (i = 0; i < BLKG_RWSTAT_NR; i++) {
586 ret = percpu_counter_init(&rwstat->cpu_cnt[i], 0, gfp);
589 percpu_counter_destroy(&rwstat->cpu_cnt[i]);
592 atomic64_set(&rwstat->aux_cnt[i], 0);
597 static inline void blkg_rwstat_exit(struct blkg_rwstat *rwstat)
601 for (i = 0; i < BLKG_RWSTAT_NR; i++)
602 percpu_counter_destroy(&rwstat->cpu_cnt[i]);
606 * blkg_rwstat_add - add a value to a blkg_rwstat
607 * @rwstat: target blkg_rwstat
608 * @op: REQ_OP and flags
611 * Add @val to @rwstat. The counters are chosen according to @rw. The
612 * caller is responsible for synchronizing calls to this function.
614 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
615 unsigned int op, uint64_t val)
617 struct percpu_counter *cnt;
619 if (op_is_discard(op))
620 cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_DISCARD];
621 else if (op_is_write(op))
622 cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_WRITE];
624 cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_READ];
626 percpu_counter_add_batch(cnt, val, BLKG_STAT_CPU_BATCH);
629 cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_SYNC];
631 cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_ASYNC];
633 percpu_counter_add_batch(cnt, val, BLKG_STAT_CPU_BATCH);
637 * blkg_rwstat_read - read the current values of a blkg_rwstat
638 * @rwstat: blkg_rwstat to read
640 * Read the current snapshot of @rwstat and return it in the aux counts.
642 static inline void blkg_rwstat_read(struct blkg_rwstat *rwstat,
643 struct blkg_rwstat_sample *result)
647 for (i = 0; i < BLKG_RWSTAT_NR; i++)
649 percpu_counter_sum_positive(&rwstat->cpu_cnt[i]);
653 * blkg_rwstat_total - read the total count of a blkg_rwstat
654 * @rwstat: blkg_rwstat to read
656 * Return the total count of @rwstat regardless of the IO direction. This
657 * function can be called without synchronization and takes care of u64
660 static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
662 struct blkg_rwstat_sample tmp = { };
664 blkg_rwstat_read(rwstat, &tmp);
665 return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
669 * blkg_rwstat_reset - reset a blkg_rwstat
670 * @rwstat: blkg_rwstat to reset
672 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
676 for (i = 0; i < BLKG_RWSTAT_NR; i++) {
677 percpu_counter_set(&rwstat->cpu_cnt[i], 0);
678 atomic64_set(&rwstat->aux_cnt[i], 0);
683 * blkg_rwstat_add_aux - add a blkg_rwstat into another's aux count
684 * @to: the destination blkg_rwstat
687 * Add @from's count including the aux one to @to's aux count.
689 static inline void blkg_rwstat_add_aux(struct blkg_rwstat *to,
690 struct blkg_rwstat *from)
692 u64 sum[BLKG_RWSTAT_NR];
695 for (i = 0; i < BLKG_RWSTAT_NR; i++)
696 sum[i] = percpu_counter_sum_positive(&from->cpu_cnt[i]);
698 for (i = 0; i < BLKG_RWSTAT_NR; i++)
699 atomic64_add(sum[i] + atomic64_read(&from->aux_cnt[i]),
703 #ifdef CONFIG_BLK_DEV_THROTTLING
704 extern bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
707 static inline bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
708 struct bio *bio) { return false; }
711 bool __blkcg_punt_bio_submit(struct bio *bio);
713 static inline bool blkcg_punt_bio_submit(struct bio *bio)
715 if (bio->bi_opf & REQ_CGROUP_PUNT)
716 return __blkcg_punt_bio_submit(bio);
721 static inline void blkcg_bio_issue_init(struct bio *bio)
723 bio_issue_init(&bio->bi_issue, bio_sectors(bio));
726 static inline bool blkcg_bio_issue_check(struct request_queue *q,
729 struct blkcg_gq *blkg;
735 char b[BDEVNAME_SIZE];
738 "no blkg associated for bio on block-device: %s\n",
739 bio_devname(bio, b));
740 bio_associate_blkg(bio);
745 throtl = blk_throtl_bio(q, blkg, bio);
749 * If the bio is flagged with BIO_QUEUE_ENTERED it means this
750 * is a split bio and we would have already accounted for the
753 if (!bio_flagged(bio, BIO_QUEUE_ENTERED))
754 blkg_rwstat_add(&blkg->stat_bytes, bio->bi_opf,
755 bio->bi_iter.bi_size);
756 blkg_rwstat_add(&blkg->stat_ios, bio->bi_opf, 1);
759 blkcg_bio_issue_init(bio);
765 static inline void blkcg_use_delay(struct blkcg_gq *blkg)
767 if (atomic_add_return(1, &blkg->use_delay) == 1)
768 atomic_inc(&blkg->blkcg->css.cgroup->congestion_count);
771 static inline int blkcg_unuse_delay(struct blkcg_gq *blkg)
773 int old = atomic_read(&blkg->use_delay);
779 * We do this song and dance because we can race with somebody else
780 * adding or removing delay. If we just did an atomic_dec we'd end up
781 * negative and we'd already be in trouble. We need to subtract 1 and
782 * then check to see if we were the last delay so we can drop the
783 * congestion count on the cgroup.
786 int cur = atomic_cmpxchg(&blkg->use_delay, old, old - 1);
795 atomic_dec(&blkg->blkcg->css.cgroup->congestion_count);
799 static inline void blkcg_clear_delay(struct blkcg_gq *blkg)
801 int old = atomic_read(&blkg->use_delay);
804 /* We only want 1 person clearing the congestion count for this blkg. */
806 int cur = atomic_cmpxchg(&blkg->use_delay, old, 0);
808 atomic_dec(&blkg->blkcg->css.cgroup->congestion_count);
815 void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta);
816 void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay);
817 void blkcg_maybe_throttle_current(void);
818 #else /* CONFIG_BLK_CGROUP */
823 struct blkg_policy_data {
826 struct blkcg_policy_data {
832 struct blkcg_policy {
835 #define blkcg_root_css ((struct cgroup_subsys_state *)ERR_PTR(-EINVAL))
837 static inline void blkcg_maybe_throttle_current(void) { }
838 static inline bool blk_cgroup_congested(void) { return false; }
842 static inline void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay) { }
844 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
845 static inline struct blkcg_gq *blk_queue_root_blkg(struct request_queue *q)
847 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
848 static inline void blkcg_drain_queue(struct request_queue *q) { }
849 static inline void blkcg_exit_queue(struct request_queue *q) { }
850 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
851 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
852 static inline int blkcg_activate_policy(struct request_queue *q,
853 const struct blkcg_policy *pol) { return 0; }
854 static inline void blkcg_deactivate_policy(struct request_queue *q,
855 const struct blkcg_policy *pol) { }
857 static inline struct blkcg *__bio_blkcg(struct bio *bio) { return NULL; }
858 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
860 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
861 struct blkcg_policy *pol) { return NULL; }
862 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
863 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
864 static inline void blkg_get(struct blkcg_gq *blkg) { }
865 static inline void blkg_put(struct blkcg_gq *blkg) { }
867 static inline bool blkcg_punt_bio_submit(struct bio *bio) { return false; }
868 static inline void blkcg_bio_issue_init(struct bio *bio) { }
869 static inline bool blkcg_bio_issue_check(struct request_queue *q,
870 struct bio *bio) { return true; }
872 #define blk_queue_for_each_rl(rl, q) \
873 for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
875 #endif /* CONFIG_BLOCK */
876 #endif /* CONFIG_BLK_CGROUP */
877 #endif /* _BLK_CGROUP_H */