2 * Common Block IO controller cgroup interface
4 * Based on ideas and code from CFQ, CFS and BFQ:
5 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
7 * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
8 * Paolo Valente <paolo.valente@unimore.it>
10 * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
11 * Nauman Rafique <nauman@google.com>
13 * For policy-specific per-blkcg data:
14 * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it>
15 * Arianna Avanzini <avanzini.arianna@gmail.com>
17 #include <linux/ioprio.h>
18 #include <linux/kdev_t.h>
19 #include <linux/module.h>
20 #include <linux/err.h>
21 #include <linux/blkdev.h>
22 #include <linux/backing-dev.h>
23 #include <linux/slab.h>
24 #include <linux/genhd.h>
25 #include <linux/delay.h>
26 #include <linux/atomic.h>
27 #include <linux/blk-cgroup.h>
30 #define MAX_KEY_LEN 100
33 * blkcg_pol_mutex protects blkcg_policy[] and policy [de]activation.
34 * blkcg_pol_register_mutex nests outside of it and synchronizes entire
35 * policy [un]register operations including cgroup file additions /
36 * removals. Putting cgroup file registration outside blkcg_pol_mutex
37 * allows grabbing it from cgroup callbacks.
39 static DEFINE_MUTEX(blkcg_pol_register_mutex);
40 static DEFINE_MUTEX(blkcg_pol_mutex);
42 struct blkcg blkcg_root;
43 EXPORT_SYMBOL_GPL(blkcg_root);
45 struct cgroup_subsys_state * const blkcg_root_css = &blkcg_root.css;
47 static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS];
49 static LIST_HEAD(all_blkcgs); /* protected by blkcg_pol_mutex */
51 static bool blkcg_policy_enabled(struct request_queue *q,
52 const struct blkcg_policy *pol)
54 return pol && test_bit(pol->plid, q->blkcg_pols);
58 * blkg_free - free a blkg
61 * Free @blkg which may be partially allocated.
63 static void blkg_free(struct blkcg_gq *blkg)
70 for (i = 0; i < BLKCG_MAX_POLS; i++)
72 blkcg_policy[i]->pd_free_fn(blkg->pd[i]);
74 if (blkg->blkcg != &blkcg_root)
75 blk_exit_rl(&blkg->rl);
77 blkg_rwstat_exit(&blkg->stat_ios);
78 blkg_rwstat_exit(&blkg->stat_bytes);
83 * blkg_alloc - allocate a blkg
84 * @blkcg: block cgroup the new blkg is associated with
85 * @q: request_queue the new blkg is associated with
86 * @gfp_mask: allocation mask to use
88 * Allocate a new blkg assocating @blkcg and @q.
90 static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q,
93 struct blkcg_gq *blkg;
96 /* alloc and init base part */
97 blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node);
101 if (blkg_rwstat_init(&blkg->stat_bytes, gfp_mask) ||
102 blkg_rwstat_init(&blkg->stat_ios, gfp_mask))
106 INIT_LIST_HEAD(&blkg->q_node);
108 atomic_set(&blkg->refcnt, 1);
110 /* root blkg uses @q->root_rl, init rl only for !root blkgs */
111 if (blkcg != &blkcg_root) {
112 if (blk_init_rl(&blkg->rl, q, gfp_mask))
114 blkg->rl.blkg = blkg;
117 for (i = 0; i < BLKCG_MAX_POLS; i++) {
118 struct blkcg_policy *pol = blkcg_policy[i];
119 struct blkg_policy_data *pd;
121 if (!blkcg_policy_enabled(q, pol))
124 /* alloc per-policy data and attach it to blkg */
125 pd = pol->pd_alloc_fn(gfp_mask, q->node);
141 struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg,
142 struct request_queue *q, bool update_hint)
144 struct blkcg_gq *blkg;
147 * Hint didn't match. Look up from the radix tree. Note that the
148 * hint can only be updated under queue_lock as otherwise @blkg
149 * could have already been removed from blkg_tree. The caller is
150 * responsible for grabbing queue_lock if @update_hint.
152 blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id);
153 if (blkg && blkg->q == q) {
155 lockdep_assert_held(q->queue_lock);
156 rcu_assign_pointer(blkcg->blkg_hint, blkg);
163 EXPORT_SYMBOL_GPL(blkg_lookup_slowpath);
166 * If @new_blkg is %NULL, this function tries to allocate a new one as
167 * necessary using %GFP_NOWAIT. @new_blkg is always consumed on return.
169 static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
170 struct request_queue *q,
171 struct blkcg_gq *new_blkg)
173 struct blkcg_gq *blkg;
174 struct bdi_writeback_congested *wb_congested;
177 WARN_ON_ONCE(!rcu_read_lock_held());
178 lockdep_assert_held(q->queue_lock);
180 /* blkg holds a reference to blkcg */
181 if (!css_tryget_online(&blkcg->css)) {
186 wb_congested = wb_congested_get_create(&q->backing_dev_info,
187 blkcg->css.id, GFP_NOWAIT);
195 new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT);
196 if (unlikely(!new_blkg)) {
198 goto err_put_congested;
202 blkg->wb_congested = wb_congested;
205 if (blkcg_parent(blkcg)) {
206 blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false);
207 if (WARN_ON_ONCE(!blkg->parent)) {
209 goto err_put_congested;
211 blkg_get(blkg->parent);
214 /* invoke per-policy init */
215 for (i = 0; i < BLKCG_MAX_POLS; i++) {
216 struct blkcg_policy *pol = blkcg_policy[i];
218 if (blkg->pd[i] && pol->pd_init_fn)
219 pol->pd_init_fn(blkg->pd[i]);
223 spin_lock(&blkcg->lock);
224 ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg);
226 hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
227 list_add(&blkg->q_node, &q->blkg_list);
229 for (i = 0; i < BLKCG_MAX_POLS; i++) {
230 struct blkcg_policy *pol = blkcg_policy[i];
232 if (blkg->pd[i] && pol->pd_online_fn)
233 pol->pd_online_fn(blkg->pd[i]);
237 spin_unlock(&blkcg->lock);
242 /* @blkg failed fully initialized, use the usual release path */
247 wb_congested_put(wb_congested);
249 css_put(&blkcg->css);
256 * blkg_lookup_create - lookup blkg, try to create one if not there
257 * @blkcg: blkcg of interest
258 * @q: request_queue of interest
260 * Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to
261 * create one. blkg creation is performed recursively from blkcg_root such
262 * that all non-root blkg's have access to the parent blkg. This function
263 * should be called under RCU read lock and @q->queue_lock.
265 * Returns pointer to the looked up or created blkg on success, ERR_PTR()
266 * value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not
267 * dead and bypassing, returns ERR_PTR(-EBUSY).
269 struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
270 struct request_queue *q)
272 struct blkcg_gq *blkg;
274 WARN_ON_ONCE(!rcu_read_lock_held());
275 lockdep_assert_held(q->queue_lock);
278 * This could be the first entry point of blkcg implementation and
279 * we shouldn't allow anything to go through for a bypassing queue.
281 if (unlikely(blk_queue_bypass(q)))
282 return ERR_PTR(blk_queue_dying(q) ? -ENODEV : -EBUSY);
284 blkg = __blkg_lookup(blkcg, q, true);
289 * Create blkgs walking down from blkcg_root to @blkcg, so that all
290 * non-root blkgs have access to their parents.
293 struct blkcg *pos = blkcg;
294 struct blkcg *parent = blkcg_parent(blkcg);
296 while (parent && !__blkg_lookup(parent, q, false)) {
298 parent = blkcg_parent(parent);
301 blkg = blkg_create(pos, q, NULL);
302 if (pos == blkcg || IS_ERR(blkg))
307 static void blkg_destroy(struct blkcg_gq *blkg)
309 struct blkcg *blkcg = blkg->blkcg;
310 struct blkcg_gq *parent = blkg->parent;
313 lockdep_assert_held(blkg->q->queue_lock);
314 lockdep_assert_held(&blkcg->lock);
316 /* Something wrong if we are trying to remove same group twice */
317 WARN_ON_ONCE(list_empty(&blkg->q_node));
318 WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node));
320 for (i = 0; i < BLKCG_MAX_POLS; i++) {
321 struct blkcg_policy *pol = blkcg_policy[i];
323 if (blkg->pd[i] && pol->pd_offline_fn)
324 pol->pd_offline_fn(blkg->pd[i]);
328 blkg_rwstat_add_aux(&parent->stat_bytes, &blkg->stat_bytes);
329 blkg_rwstat_add_aux(&parent->stat_ios, &blkg->stat_ios);
332 blkg->online = false;
334 radix_tree_delete(&blkcg->blkg_tree, blkg->q->id);
335 list_del_init(&blkg->q_node);
336 hlist_del_init_rcu(&blkg->blkcg_node);
339 * Both setting lookup hint to and clearing it from @blkg are done
340 * under queue_lock. If it's not pointing to @blkg now, it never
341 * will. Hint assignment itself can race safely.
343 if (rcu_access_pointer(blkcg->blkg_hint) == blkg)
344 rcu_assign_pointer(blkcg->blkg_hint, NULL);
347 * Put the reference taken at the time of creation so that when all
348 * queues are gone, group can be destroyed.
354 * blkg_destroy_all - destroy all blkgs associated with a request_queue
355 * @q: request_queue of interest
357 * Destroy all blkgs associated with @q.
359 static void blkg_destroy_all(struct request_queue *q)
361 struct blkcg_gq *blkg, *n;
363 lockdep_assert_held(q->queue_lock);
365 list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
366 struct blkcg *blkcg = blkg->blkcg;
368 spin_lock(&blkcg->lock);
370 spin_unlock(&blkcg->lock);
375 * A group is RCU protected, but having an rcu lock does not mean that one
376 * can access all the fields of blkg and assume these are valid. For
377 * example, don't try to follow throtl_data and request queue links.
379 * Having a reference to blkg under an rcu allows accesses to only values
380 * local to groups like group stats and group rate limits.
382 void __blkg_release_rcu(struct rcu_head *rcu_head)
384 struct blkcg_gq *blkg = container_of(rcu_head, struct blkcg_gq, rcu_head);
386 /* release the blkcg and parent blkg refs this blkg has been holding */
387 css_put(&blkg->blkcg->css);
389 blkg_put(blkg->parent);
391 wb_congested_put(blkg->wb_congested);
395 EXPORT_SYMBOL_GPL(__blkg_release_rcu);
398 * The next function used by blk_queue_for_each_rl(). It's a bit tricky
399 * because the root blkg uses @q->root_rl instead of its own rl.
401 struct request_list *__blk_queue_next_rl(struct request_list *rl,
402 struct request_queue *q)
404 struct list_head *ent;
405 struct blkcg_gq *blkg;
408 * Determine the current blkg list_head. The first entry is
409 * root_rl which is off @q->blkg_list and mapped to the head.
411 if (rl == &q->root_rl) {
413 /* There are no more block groups, hence no request lists */
417 blkg = container_of(rl, struct blkcg_gq, rl);
421 /* walk to the next list_head, skip root blkcg */
423 if (ent == &q->root_blkg->q_node)
425 if (ent == &q->blkg_list)
428 blkg = container_of(ent, struct blkcg_gq, q_node);
432 static int blkcg_reset_stats(struct cgroup_subsys_state *css,
433 struct cftype *cftype, u64 val)
435 struct blkcg *blkcg = css_to_blkcg(css);
436 struct blkcg_gq *blkg;
439 mutex_lock(&blkcg_pol_mutex);
440 spin_lock_irq(&blkcg->lock);
443 * Note that stat reset is racy - it doesn't synchronize against
444 * stat updates. This is a debug feature which shouldn't exist
445 * anyway. If you get hit by a race, retry.
447 hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
448 blkg_rwstat_reset(&blkg->stat_bytes);
449 blkg_rwstat_reset(&blkg->stat_ios);
451 for (i = 0; i < BLKCG_MAX_POLS; i++) {
452 struct blkcg_policy *pol = blkcg_policy[i];
454 if (blkg->pd[i] && pol->pd_reset_stats_fn)
455 pol->pd_reset_stats_fn(blkg->pd[i]);
459 spin_unlock_irq(&blkcg->lock);
460 mutex_unlock(&blkcg_pol_mutex);
464 static const char *blkg_dev_name(struct blkcg_gq *blkg)
466 /* some drivers (floppy) instantiate a queue w/o disk registered */
467 if (blkg->q->backing_dev_info.dev)
468 return dev_name(blkg->q->backing_dev_info.dev);
473 * blkcg_print_blkgs - helper for printing per-blkg data
474 * @sf: seq_file to print to
475 * @blkcg: blkcg of interest
476 * @prfill: fill function to print out a blkg
477 * @pol: policy in question
478 * @data: data to be passed to @prfill
479 * @show_total: to print out sum of prfill return values or not
481 * This function invokes @prfill on each blkg of @blkcg if pd for the
482 * policy specified by @pol exists. @prfill is invoked with @sf, the
483 * policy data and @data and the matching queue lock held. If @show_total
484 * is %true, the sum of the return values from @prfill is printed with
485 * "Total" label at the end.
487 * This is to be used to construct print functions for
488 * cftype->read_seq_string method.
490 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
491 u64 (*prfill)(struct seq_file *,
492 struct blkg_policy_data *, int),
493 const struct blkcg_policy *pol, int data,
496 struct blkcg_gq *blkg;
500 hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) {
501 spin_lock_irq(blkg->q->queue_lock);
502 if (blkcg_policy_enabled(blkg->q, pol))
503 total += prfill(sf, blkg->pd[pol->plid], data);
504 spin_unlock_irq(blkg->q->queue_lock);
509 seq_printf(sf, "Total %llu\n", (unsigned long long)total);
511 EXPORT_SYMBOL_GPL(blkcg_print_blkgs);
514 * __blkg_prfill_u64 - prfill helper for a single u64 value
515 * @sf: seq_file to print to
516 * @pd: policy private data of interest
519 * Print @v to @sf for the device assocaited with @pd.
521 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v)
523 const char *dname = blkg_dev_name(pd->blkg);
528 seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v);
531 EXPORT_SYMBOL_GPL(__blkg_prfill_u64);
534 * __blkg_prfill_rwstat - prfill helper for a blkg_rwstat
535 * @sf: seq_file to print to
536 * @pd: policy private data of interest
537 * @rwstat: rwstat to print
539 * Print @rwstat to @sf for the device assocaited with @pd.
541 u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
542 const struct blkg_rwstat *rwstat)
544 static const char *rwstr[] = {
545 [BLKG_RWSTAT_READ] = "Read",
546 [BLKG_RWSTAT_WRITE] = "Write",
547 [BLKG_RWSTAT_SYNC] = "Sync",
548 [BLKG_RWSTAT_ASYNC] = "Async",
550 const char *dname = blkg_dev_name(pd->blkg);
557 for (i = 0; i < BLKG_RWSTAT_NR; i++)
558 seq_printf(sf, "%s %s %llu\n", dname, rwstr[i],
559 (unsigned long long)atomic64_read(&rwstat->aux_cnt[i]));
561 v = atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_READ]) +
562 atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_WRITE]);
563 seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v);
566 EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat);
569 * blkg_prfill_stat - prfill callback for blkg_stat
570 * @sf: seq_file to print to
571 * @pd: policy private data of interest
572 * @off: offset to the blkg_stat in @pd
574 * prfill callback for printing a blkg_stat.
576 u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off)
578 return __blkg_prfill_u64(sf, pd, blkg_stat_read((void *)pd + off));
580 EXPORT_SYMBOL_GPL(blkg_prfill_stat);
583 * blkg_prfill_rwstat - prfill callback for blkg_rwstat
584 * @sf: seq_file to print to
585 * @pd: policy private data of interest
586 * @off: offset to the blkg_rwstat in @pd
588 * prfill callback for printing a blkg_rwstat.
590 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
593 struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd + off);
595 return __blkg_prfill_rwstat(sf, pd, &rwstat);
597 EXPORT_SYMBOL_GPL(blkg_prfill_rwstat);
599 static u64 blkg_prfill_rwstat_field(struct seq_file *sf,
600 struct blkg_policy_data *pd, int off)
602 struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd->blkg + off);
604 return __blkg_prfill_rwstat(sf, pd, &rwstat);
608 * blkg_print_stat_bytes - seq_show callback for blkg->stat_bytes
609 * @sf: seq_file to print to
612 * To be used as cftype->seq_show to print blkg->stat_bytes.
613 * cftype->private must be set to the blkcg_policy.
615 int blkg_print_stat_bytes(struct seq_file *sf, void *v)
617 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
618 blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private,
619 offsetof(struct blkcg_gq, stat_bytes), true);
622 EXPORT_SYMBOL_GPL(blkg_print_stat_bytes);
625 * blkg_print_stat_bytes - seq_show callback for blkg->stat_ios
626 * @sf: seq_file to print to
629 * To be used as cftype->seq_show to print blkg->stat_ios. cftype->private
630 * must be set to the blkcg_policy.
632 int blkg_print_stat_ios(struct seq_file *sf, void *v)
634 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
635 blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private,
636 offsetof(struct blkcg_gq, stat_ios), true);
639 EXPORT_SYMBOL_GPL(blkg_print_stat_ios);
641 static u64 blkg_prfill_rwstat_field_recursive(struct seq_file *sf,
642 struct blkg_policy_data *pd,
645 struct blkg_rwstat rwstat = blkg_rwstat_recursive_sum(pd->blkg,
647 return __blkg_prfill_rwstat(sf, pd, &rwstat);
651 * blkg_print_stat_bytes_recursive - recursive version of blkg_print_stat_bytes
652 * @sf: seq_file to print to
655 int blkg_print_stat_bytes_recursive(struct seq_file *sf, void *v)
657 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
658 blkg_prfill_rwstat_field_recursive,
659 (void *)seq_cft(sf)->private,
660 offsetof(struct blkcg_gq, stat_bytes), true);
663 EXPORT_SYMBOL_GPL(blkg_print_stat_bytes_recursive);
666 * blkg_print_stat_ios_recursive - recursive version of blkg_print_stat_ios
667 * @sf: seq_file to print to
670 int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v)
672 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
673 blkg_prfill_rwstat_field_recursive,
674 (void *)seq_cft(sf)->private,
675 offsetof(struct blkcg_gq, stat_ios), true);
678 EXPORT_SYMBOL_GPL(blkg_print_stat_ios_recursive);
681 * blkg_stat_recursive_sum - collect hierarchical blkg_stat
682 * @blkg: blkg of interest
683 * @pol: blkcg_policy which contains the blkg_stat
684 * @off: offset to the blkg_stat in blkg_policy_data or @blkg
686 * Collect the blkg_stat specified by @blkg, @pol and @off and all its
687 * online descendants and their aux counts. The caller must be holding the
688 * queue lock for online tests.
690 * If @pol is NULL, blkg_stat is at @off bytes into @blkg; otherwise, it is
691 * at @off bytes into @blkg's blkg_policy_data of the policy.
693 u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg,
694 struct blkcg_policy *pol, int off)
696 struct blkcg_gq *pos_blkg;
697 struct cgroup_subsys_state *pos_css;
700 lockdep_assert_held(blkg->q->queue_lock);
703 blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
704 struct blkg_stat *stat;
706 if (!pos_blkg->online)
710 stat = (void *)blkg_to_pd(pos_blkg, pol) + off;
712 stat = (void *)blkg + off;
714 sum += blkg_stat_read(stat) + atomic64_read(&stat->aux_cnt);
720 EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum);
723 * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat
724 * @blkg: blkg of interest
725 * @pol: blkcg_policy which contains the blkg_rwstat
726 * @off: offset to the blkg_rwstat in blkg_policy_data or @blkg
728 * Collect the blkg_rwstat specified by @blkg, @pol and @off and all its
729 * online descendants and their aux counts. The caller must be holding the
730 * queue lock for online tests.
732 * If @pol is NULL, blkg_rwstat is at @off bytes into @blkg; otherwise, it
733 * is at @off bytes into @blkg's blkg_policy_data of the policy.
735 struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg,
736 struct blkcg_policy *pol, int off)
738 struct blkcg_gq *pos_blkg;
739 struct cgroup_subsys_state *pos_css;
740 struct blkg_rwstat sum = { };
743 lockdep_assert_held(blkg->q->queue_lock);
746 blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
747 struct blkg_rwstat *rwstat;
749 if (!pos_blkg->online)
753 rwstat = (void *)blkg_to_pd(pos_blkg, pol) + off;
755 rwstat = (void *)pos_blkg + off;
757 for (i = 0; i < BLKG_RWSTAT_NR; i++)
758 atomic64_add(atomic64_read(&rwstat->aux_cnt[i]) +
759 percpu_counter_sum_positive(&rwstat->cpu_cnt[i]),
766 EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum);
769 * blkg_conf_prep - parse and prepare for per-blkg config update
770 * @blkcg: target block cgroup
771 * @pol: target policy
772 * @input: input string
773 * @ctx: blkg_conf_ctx to be filled
775 * Parse per-blkg config update from @input and initialize @ctx with the
776 * result. @ctx->blkg points to the blkg to be updated and @ctx->v the new
777 * value. This function returns with RCU read lock and queue lock held and
778 * must be paired with blkg_conf_finish().
780 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
781 const char *input, struct blkg_conf_ctx *ctx)
782 __acquires(rcu) __acquires(disk->queue->queue_lock)
784 struct gendisk *disk;
785 struct blkcg_gq *blkg;
786 unsigned int major, minor;
787 unsigned long long v;
790 if (sscanf(input, "%u:%u %llu", &major, &minor, &v) != 3)
793 disk = get_gendisk(MKDEV(major, minor), &part);
802 spin_lock_irq(disk->queue->queue_lock);
804 if (blkcg_policy_enabled(disk->queue, pol))
805 blkg = blkg_lookup_create(blkcg, disk->queue);
807 blkg = ERR_PTR(-EOPNOTSUPP);
812 spin_unlock_irq(disk->queue->queue_lock);
815 * If queue was bypassing, we should retry. Do so after a
816 * short msleep(). It isn't strictly necessary but queue
817 * can be bypassing for some time and it's always nice to
818 * avoid busy looping.
822 ret = restart_syscall();
832 EXPORT_SYMBOL_GPL(blkg_conf_prep);
835 * blkg_conf_finish - finish up per-blkg config update
836 * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep()
838 * Finish up after per-blkg config update. This function must be paired
839 * with blkg_conf_prep().
841 void blkg_conf_finish(struct blkg_conf_ctx *ctx)
842 __releases(ctx->disk->queue->queue_lock) __releases(rcu)
844 spin_unlock_irq(ctx->disk->queue->queue_lock);
848 EXPORT_SYMBOL_GPL(blkg_conf_finish);
850 struct cftype blkcg_files[] = {
852 .name = "reset_stats",
853 .write_u64 = blkcg_reset_stats,
859 * blkcg_css_offline - cgroup css_offline callback
860 * @css: css of interest
862 * This function is called when @css is about to go away and responsible
863 * for shooting down all blkgs associated with @css. blkgs should be
864 * removed while holding both q and blkcg locks. As blkcg lock is nested
865 * inside q lock, this function performs reverse double lock dancing.
867 * This is the blkcg counterpart of ioc_release_fn().
869 static void blkcg_css_offline(struct cgroup_subsys_state *css)
871 struct blkcg *blkcg = css_to_blkcg(css);
873 spin_lock_irq(&blkcg->lock);
875 while (!hlist_empty(&blkcg->blkg_list)) {
876 struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first,
877 struct blkcg_gq, blkcg_node);
878 struct request_queue *q = blkg->q;
880 if (spin_trylock(q->queue_lock)) {
882 spin_unlock(q->queue_lock);
884 spin_unlock_irq(&blkcg->lock);
886 spin_lock_irq(&blkcg->lock);
890 spin_unlock_irq(&blkcg->lock);
892 wb_blkcg_offline(blkcg);
895 static void blkcg_css_free(struct cgroup_subsys_state *css)
897 struct blkcg *blkcg = css_to_blkcg(css);
900 mutex_lock(&blkcg_pol_mutex);
902 list_del(&blkcg->all_blkcgs_node);
904 for (i = 0; i < BLKCG_MAX_POLS; i++)
906 blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]);
908 mutex_unlock(&blkcg_pol_mutex);
913 static struct cgroup_subsys_state *
914 blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
917 struct cgroup_subsys_state *ret;
920 mutex_lock(&blkcg_pol_mutex);
925 blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
927 ret = ERR_PTR(-ENOMEM);
932 for (i = 0; i < BLKCG_MAX_POLS ; i++) {
933 struct blkcg_policy *pol = blkcg_policy[i];
934 struct blkcg_policy_data *cpd;
937 * If the policy hasn't been attached yet, wait for it
938 * to be attached before doing anything else. Otherwise,
939 * check if the policy requires any specific per-cgroup
940 * data: if it does, allocate and initialize it.
942 if (!pol || !pol->cpd_alloc_fn)
945 cpd = pol->cpd_alloc_fn(GFP_KERNEL);
947 ret = ERR_PTR(-ENOMEM);
953 if (pol->cpd_init_fn)
954 pol->cpd_init_fn(cpd);
957 spin_lock_init(&blkcg->lock);
958 INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT);
959 INIT_HLIST_HEAD(&blkcg->blkg_list);
960 #ifdef CONFIG_CGROUP_WRITEBACK
961 INIT_LIST_HEAD(&blkcg->cgwb_list);
963 list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs);
965 mutex_unlock(&blkcg_pol_mutex);
969 for (i--; i >= 0; i--)
971 blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]);
974 mutex_unlock(&blkcg_pol_mutex);
979 * blkcg_init_queue - initialize blkcg part of request queue
980 * @q: request_queue to initialize
982 * Called from blk_alloc_queue_node(). Responsible for initializing blkcg
983 * part of new request_queue @q.
986 * 0 on success, -errno on failure.
988 int blkcg_init_queue(struct request_queue *q)
990 struct blkcg_gq *new_blkg, *blkg;
994 new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL);
998 preloaded = !radix_tree_preload(GFP_KERNEL);
1001 * Make sure the root blkg exists and count the existing blkgs. As
1002 * @q is bypassing at this point, blkg_lookup_create() can't be
1003 * used. Open code insertion.
1006 spin_lock_irq(q->queue_lock);
1007 blkg = blkg_create(&blkcg_root, q, new_blkg);
1008 spin_unlock_irq(q->queue_lock);
1012 radix_tree_preload_end();
1015 blkg_free(new_blkg);
1016 return PTR_ERR(blkg);
1019 q->root_blkg = blkg;
1020 q->root_rl.blkg = blkg;
1022 ret = blk_throtl_init(q);
1024 spin_lock_irq(q->queue_lock);
1025 blkg_destroy_all(q);
1026 spin_unlock_irq(q->queue_lock);
1032 * blkcg_drain_queue - drain blkcg part of request_queue
1033 * @q: request_queue to drain
1035 * Called from blk_drain_queue(). Responsible for draining blkcg part.
1037 void blkcg_drain_queue(struct request_queue *q)
1039 lockdep_assert_held(q->queue_lock);
1042 * @q could be exiting and already have destroyed all blkgs as
1043 * indicated by NULL root_blkg. If so, don't confuse policies.
1048 blk_throtl_drain(q);
1052 * blkcg_exit_queue - exit and release blkcg part of request_queue
1053 * @q: request_queue being released
1055 * Called from blk_release_queue(). Responsible for exiting blkcg part.
1057 void blkcg_exit_queue(struct request_queue *q)
1059 spin_lock_irq(q->queue_lock);
1060 blkg_destroy_all(q);
1061 spin_unlock_irq(q->queue_lock);
1067 * We cannot support shared io contexts, as we have no mean to support
1068 * two tasks with the same ioc in two different groups without major rework
1069 * of the main cic data structures. For now we allow a task to change
1070 * its cgroup only if it's the only owner of its ioc.
1072 static int blkcg_can_attach(struct cgroup_subsys_state *css,
1073 struct cgroup_taskset *tset)
1075 struct task_struct *task;
1076 struct io_context *ioc;
1079 /* task_lock() is needed to avoid races with exit_io_context() */
1080 cgroup_taskset_for_each(task, tset) {
1082 ioc = task->io_context;
1083 if (ioc && atomic_read(&ioc->nr_tasks) > 1)
1092 struct cgroup_subsys io_cgrp_subsys = {
1093 .css_alloc = blkcg_css_alloc,
1094 .css_offline = blkcg_css_offline,
1095 .css_free = blkcg_css_free,
1096 .can_attach = blkcg_can_attach,
1097 .legacy_cftypes = blkcg_files,
1098 .legacy_name = "blkio",
1101 * This ensures that, if available, memcg is automatically enabled
1102 * together on the default hierarchy so that the owner cgroup can
1103 * be retrieved from writeback pages.
1105 .depends_on = 1 << memory_cgrp_id,
1108 EXPORT_SYMBOL_GPL(io_cgrp_subsys);
1111 * blkcg_activate_policy - activate a blkcg policy on a request_queue
1112 * @q: request_queue of interest
1113 * @pol: blkcg policy to activate
1115 * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through
1116 * bypass mode to populate its blkgs with policy_data for @pol.
1118 * Activation happens with @q bypassed, so nobody would be accessing blkgs
1119 * from IO path. Update of each blkg is protected by both queue and blkcg
1120 * locks so that holding either lock and testing blkcg_policy_enabled() is
1121 * always enough for dereferencing policy data.
1123 * The caller is responsible for synchronizing [de]activations and policy
1124 * [un]registerations. Returns 0 on success, -errno on failure.
1126 int blkcg_activate_policy(struct request_queue *q,
1127 const struct blkcg_policy *pol)
1129 struct blkg_policy_data *pd_prealloc = NULL;
1130 struct blkcg_gq *blkg;
1133 if (blkcg_policy_enabled(q, pol))
1136 blk_queue_bypass_start(q);
1139 pd_prealloc = pol->pd_alloc_fn(GFP_KERNEL, q->node);
1142 goto out_bypass_end;
1146 spin_lock_irq(q->queue_lock);
1148 list_for_each_entry(blkg, &q->blkg_list, q_node) {
1149 struct blkg_policy_data *pd;
1151 if (blkg->pd[pol->plid])
1154 pd = pol->pd_alloc_fn(GFP_NOWAIT, q->node);
1156 swap(pd, pd_prealloc);
1158 spin_unlock_irq(q->queue_lock);
1162 blkg->pd[pol->plid] = pd;
1164 pd->plid = pol->plid;
1165 if (pol->pd_init_fn)
1166 pol->pd_init_fn(pd);
1169 __set_bit(pol->plid, q->blkcg_pols);
1172 spin_unlock_irq(q->queue_lock);
1174 blk_queue_bypass_end(q);
1176 pol->pd_free_fn(pd_prealloc);
1179 EXPORT_SYMBOL_GPL(blkcg_activate_policy);
1182 * blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue
1183 * @q: request_queue of interest
1184 * @pol: blkcg policy to deactivate
1186 * Deactivate @pol on @q. Follows the same synchronization rules as
1187 * blkcg_activate_policy().
1189 void blkcg_deactivate_policy(struct request_queue *q,
1190 const struct blkcg_policy *pol)
1192 struct blkcg_gq *blkg;
1194 if (!blkcg_policy_enabled(q, pol))
1197 blk_queue_bypass_start(q);
1198 spin_lock_irq(q->queue_lock);
1200 __clear_bit(pol->plid, q->blkcg_pols);
1202 list_for_each_entry(blkg, &q->blkg_list, q_node) {
1203 /* grab blkcg lock too while removing @pd from @blkg */
1204 spin_lock(&blkg->blkcg->lock);
1206 if (blkg->pd[pol->plid]) {
1207 if (pol->pd_offline_fn)
1208 pol->pd_offline_fn(blkg->pd[pol->plid]);
1209 pol->pd_free_fn(blkg->pd[pol->plid]);
1210 blkg->pd[pol->plid] = NULL;
1213 spin_unlock(&blkg->blkcg->lock);
1216 spin_unlock_irq(q->queue_lock);
1217 blk_queue_bypass_end(q);
1219 EXPORT_SYMBOL_GPL(blkcg_deactivate_policy);
1222 * blkcg_policy_register - register a blkcg policy
1223 * @pol: blkcg policy to register
1225 * Register @pol with blkcg core. Might sleep and @pol may be modified on
1226 * successful registration. Returns 0 on success and -errno on failure.
1228 int blkcg_policy_register(struct blkcg_policy *pol)
1230 struct blkcg *blkcg;
1233 mutex_lock(&blkcg_pol_register_mutex);
1234 mutex_lock(&blkcg_pol_mutex);
1236 /* find an empty slot */
1238 for (i = 0; i < BLKCG_MAX_POLS; i++)
1239 if (!blkcg_policy[i])
1241 if (i >= BLKCG_MAX_POLS)
1246 blkcg_policy[pol->plid] = pol;
1248 /* allocate and install cpd's */
1249 if (pol->cpd_alloc_fn) {
1250 list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
1251 struct blkcg_policy_data *cpd;
1253 cpd = pol->cpd_alloc_fn(GFP_KERNEL);
1255 mutex_unlock(&blkcg_pol_mutex);
1259 blkcg->cpd[pol->plid] = cpd;
1261 cpd->plid = pol->plid;
1262 pol->cpd_init_fn(cpd);
1266 mutex_unlock(&blkcg_pol_mutex);
1268 /* everything is in place, add intf files for the new policy */
1270 WARN_ON(cgroup_add_legacy_cftypes(&io_cgrp_subsys,
1272 mutex_unlock(&blkcg_pol_register_mutex);
1276 if (pol->cpd_alloc_fn) {
1277 list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
1278 if (blkcg->cpd[pol->plid]) {
1279 pol->cpd_free_fn(blkcg->cpd[pol->plid]);
1280 blkcg->cpd[pol->plid] = NULL;
1284 blkcg_policy[pol->plid] = NULL;
1286 mutex_unlock(&blkcg_pol_mutex);
1287 mutex_unlock(&blkcg_pol_register_mutex);
1290 EXPORT_SYMBOL_GPL(blkcg_policy_register);
1293 * blkcg_policy_unregister - unregister a blkcg policy
1294 * @pol: blkcg policy to unregister
1296 * Undo blkcg_policy_register(@pol). Might sleep.
1298 void blkcg_policy_unregister(struct blkcg_policy *pol)
1300 struct blkcg *blkcg;
1302 mutex_lock(&blkcg_pol_register_mutex);
1304 if (WARN_ON(blkcg_policy[pol->plid] != pol))
1307 /* kill the intf files first */
1309 cgroup_rm_cftypes(pol->cftypes);
1311 /* remove cpds and unregister */
1312 mutex_lock(&blkcg_pol_mutex);
1314 if (pol->cpd_alloc_fn) {
1315 list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
1316 if (blkcg->cpd[pol->plid]) {
1317 pol->cpd_free_fn(blkcg->cpd[pol->plid]);
1318 blkcg->cpd[pol->plid] = NULL;
1322 blkcg_policy[pol->plid] = NULL;
1324 mutex_unlock(&blkcg_pol_mutex);
1326 mutex_unlock(&blkcg_pol_register_mutex);
1328 EXPORT_SYMBOL_GPL(blkcg_policy_unregister);