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
++)
73 blk_exit_rl(&blkg
->rl
);
78 * blkg_alloc - allocate a blkg
79 * @blkcg: block cgroup the new blkg is associated with
80 * @q: request_queue the new blkg is associated with
81 * @gfp_mask: allocation mask to use
83 * Allocate a new blkg assocating @blkcg and @q.
85 static struct blkcg_gq
*blkg_alloc(struct blkcg
*blkcg
, struct request_queue
*q
,
88 struct blkcg_gq
*blkg
;
91 /* alloc and init base part */
92 blkg
= kzalloc_node(sizeof(*blkg
), gfp_mask
, q
->node
);
97 INIT_LIST_HEAD(&blkg
->q_node
);
99 atomic_set(&blkg
->refcnt
, 1);
101 /* root blkg uses @q->root_rl, init rl only for !root blkgs */
102 if (blkcg
!= &blkcg_root
) {
103 if (blk_init_rl(&blkg
->rl
, q
, gfp_mask
))
105 blkg
->rl
.blkg
= blkg
;
108 for (i
= 0; i
< BLKCG_MAX_POLS
; i
++) {
109 struct blkcg_policy
*pol
= blkcg_policy
[i
];
110 struct blkg_policy_data
*pd
;
112 if (!blkcg_policy_enabled(q
, pol
))
115 /* alloc per-policy data and attach it to blkg */
116 pd
= kzalloc_node(pol
->pd_size
, gfp_mask
, q
->node
);
133 * __blkg_lookup - internal version of blkg_lookup()
134 * @blkcg: blkcg of interest
135 * @q: request_queue of interest
136 * @update_hint: whether to update lookup hint with the result or not
138 * This is internal version and shouldn't be used by policy
139 * implementations. Looks up blkgs for the @blkcg - @q pair regardless of
140 * @q's bypass state. If @update_hint is %true, the caller should be
141 * holding @q->queue_lock and lookup hint is updated on success.
143 struct blkcg_gq
*__blkg_lookup(struct blkcg
*blkcg
, struct request_queue
*q
,
146 struct blkcg_gq
*blkg
;
148 blkg
= rcu_dereference(blkcg
->blkg_hint
);
149 if (blkg
&& blkg
->q
== q
)
153 * Hint didn't match. Look up from the radix tree. Note that the
154 * hint can only be updated under queue_lock as otherwise @blkg
155 * could have already been removed from blkg_tree. The caller is
156 * responsible for grabbing queue_lock if @update_hint.
158 blkg
= radix_tree_lookup(&blkcg
->blkg_tree
, q
->id
);
159 if (blkg
&& blkg
->q
== q
) {
161 lockdep_assert_held(q
->queue_lock
);
162 rcu_assign_pointer(blkcg
->blkg_hint
, blkg
);
171 * blkg_lookup - lookup blkg for the specified blkcg - q pair
172 * @blkcg: blkcg of interest
173 * @q: request_queue of interest
175 * Lookup blkg for the @blkcg - @q pair. This function should be called
176 * under RCU read lock and is guaranteed to return %NULL if @q is bypassing
177 * - see blk_queue_bypass_start() for details.
179 struct blkcg_gq
*blkg_lookup(struct blkcg
*blkcg
, struct request_queue
*q
)
181 WARN_ON_ONCE(!rcu_read_lock_held());
183 if (unlikely(blk_queue_bypass(q
)))
185 return __blkg_lookup(blkcg
, q
, false);
187 EXPORT_SYMBOL_GPL(blkg_lookup
);
190 * If @new_blkg is %NULL, this function tries to allocate a new one as
191 * necessary using %GFP_ATOMIC. @new_blkg is always consumed on return.
193 static struct blkcg_gq
*blkg_create(struct blkcg
*blkcg
,
194 struct request_queue
*q
,
195 struct blkcg_gq
*new_blkg
)
197 struct blkcg_gq
*blkg
;
198 struct bdi_writeback_congested
*wb_congested
;
201 WARN_ON_ONCE(!rcu_read_lock_held());
202 lockdep_assert_held(q
->queue_lock
);
204 /* blkg holds a reference to blkcg */
205 if (!css_tryget_online(&blkcg
->css
)) {
210 wb_congested
= wb_congested_get_create(&q
->backing_dev_info
,
211 blkcg
->css
.id
, GFP_ATOMIC
);
219 new_blkg
= blkg_alloc(blkcg
, q
, GFP_ATOMIC
);
220 if (unlikely(!new_blkg
)) {
222 goto err_put_congested
;
226 blkg
->wb_congested
= wb_congested
;
229 if (blkcg_parent(blkcg
)) {
230 blkg
->parent
= __blkg_lookup(blkcg_parent(blkcg
), q
, false);
231 if (WARN_ON_ONCE(!blkg
->parent
)) {
233 goto err_put_congested
;
235 blkg_get(blkg
->parent
);
238 /* invoke per-policy init */
239 for (i
= 0; i
< BLKCG_MAX_POLS
; i
++) {
240 struct blkcg_policy
*pol
= blkcg_policy
[i
];
242 if (blkg
->pd
[i
] && pol
->pd_init_fn
)
243 pol
->pd_init_fn(blkg
);
247 spin_lock(&blkcg
->lock
);
248 ret
= radix_tree_insert(&blkcg
->blkg_tree
, q
->id
, blkg
);
250 hlist_add_head_rcu(&blkg
->blkcg_node
, &blkcg
->blkg_list
);
251 list_add(&blkg
->q_node
, &q
->blkg_list
);
253 for (i
= 0; i
< BLKCG_MAX_POLS
; i
++) {
254 struct blkcg_policy
*pol
= blkcg_policy
[i
];
256 if (blkg
->pd
[i
] && pol
->pd_online_fn
)
257 pol
->pd_online_fn(blkg
);
261 spin_unlock(&blkcg
->lock
);
266 /* @blkg failed fully initialized, use the usual release path */
271 wb_congested_put(wb_congested
);
273 css_put(&blkcg
->css
);
280 * blkg_lookup_create - lookup blkg, try to create one if not there
281 * @blkcg: blkcg of interest
282 * @q: request_queue of interest
284 * Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to
285 * create one. blkg creation is performed recursively from blkcg_root such
286 * that all non-root blkg's have access to the parent blkg. This function
287 * should be called under RCU read lock and @q->queue_lock.
289 * Returns pointer to the looked up or created blkg on success, ERR_PTR()
290 * value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not
291 * dead and bypassing, returns ERR_PTR(-EBUSY).
293 struct blkcg_gq
*blkg_lookup_create(struct blkcg
*blkcg
,
294 struct request_queue
*q
)
296 struct blkcg_gq
*blkg
;
298 WARN_ON_ONCE(!rcu_read_lock_held());
299 lockdep_assert_held(q
->queue_lock
);
302 * This could be the first entry point of blkcg implementation and
303 * we shouldn't allow anything to go through for a bypassing queue.
305 if (unlikely(blk_queue_bypass(q
)))
306 return ERR_PTR(blk_queue_dying(q
) ? -EINVAL
: -EBUSY
);
308 blkg
= __blkg_lookup(blkcg
, q
, true);
313 * Create blkgs walking down from blkcg_root to @blkcg, so that all
314 * non-root blkgs have access to their parents.
317 struct blkcg
*pos
= blkcg
;
318 struct blkcg
*parent
= blkcg_parent(blkcg
);
320 while (parent
&& !__blkg_lookup(parent
, q
, false)) {
322 parent
= blkcg_parent(parent
);
325 blkg
= blkg_create(pos
, q
, NULL
);
326 if (pos
== blkcg
|| IS_ERR(blkg
))
330 EXPORT_SYMBOL_GPL(blkg_lookup_create
);
332 static void blkg_destroy(struct blkcg_gq
*blkg
)
334 struct blkcg
*blkcg
= blkg
->blkcg
;
337 lockdep_assert_held(blkg
->q
->queue_lock
);
338 lockdep_assert_held(&blkcg
->lock
);
340 /* Something wrong if we are trying to remove same group twice */
341 WARN_ON_ONCE(list_empty(&blkg
->q_node
));
342 WARN_ON_ONCE(hlist_unhashed(&blkg
->blkcg_node
));
344 for (i
= 0; i
< BLKCG_MAX_POLS
; i
++) {
345 struct blkcg_policy
*pol
= blkcg_policy
[i
];
347 if (blkg
->pd
[i
] && pol
->pd_offline_fn
)
348 pol
->pd_offline_fn(blkg
);
350 blkg
->online
= false;
352 radix_tree_delete(&blkcg
->blkg_tree
, blkg
->q
->id
);
353 list_del_init(&blkg
->q_node
);
354 hlist_del_init_rcu(&blkg
->blkcg_node
);
357 * Both setting lookup hint to and clearing it from @blkg are done
358 * under queue_lock. If it's not pointing to @blkg now, it never
359 * will. Hint assignment itself can race safely.
361 if (rcu_access_pointer(blkcg
->blkg_hint
) == blkg
)
362 rcu_assign_pointer(blkcg
->blkg_hint
, NULL
);
365 * Put the reference taken at the time of creation so that when all
366 * queues are gone, group can be destroyed.
372 * blkg_destroy_all - destroy all blkgs associated with a request_queue
373 * @q: request_queue of interest
375 * Destroy all blkgs associated with @q.
377 static void blkg_destroy_all(struct request_queue
*q
)
379 struct blkcg_gq
*blkg
, *n
;
381 lockdep_assert_held(q
->queue_lock
);
383 list_for_each_entry_safe(blkg
, n
, &q
->blkg_list
, q_node
) {
384 struct blkcg
*blkcg
= blkg
->blkcg
;
386 spin_lock(&blkcg
->lock
);
388 spin_unlock(&blkcg
->lock
);
392 q
->root_rl
.blkg
= NULL
;
396 * A group is RCU protected, but having an rcu lock does not mean that one
397 * can access all the fields of blkg and assume these are valid. For
398 * example, don't try to follow throtl_data and request queue links.
400 * Having a reference to blkg under an rcu allows accesses to only values
401 * local to groups like group stats and group rate limits.
403 void __blkg_release_rcu(struct rcu_head
*rcu_head
)
405 struct blkcg_gq
*blkg
= container_of(rcu_head
, struct blkcg_gq
, rcu_head
);
408 /* tell policies that this one is being freed */
409 for (i
= 0; i
< BLKCG_MAX_POLS
; i
++) {
410 struct blkcg_policy
*pol
= blkcg_policy
[i
];
412 if (blkg
->pd
[i
] && pol
->pd_exit_fn
)
413 pol
->pd_exit_fn(blkg
);
416 /* release the blkcg and parent blkg refs this blkg has been holding */
417 css_put(&blkg
->blkcg
->css
);
419 blkg_put(blkg
->parent
);
421 wb_congested_put(blkg
->wb_congested
);
425 EXPORT_SYMBOL_GPL(__blkg_release_rcu
);
428 * The next function used by blk_queue_for_each_rl(). It's a bit tricky
429 * because the root blkg uses @q->root_rl instead of its own rl.
431 struct request_list
*__blk_queue_next_rl(struct request_list
*rl
,
432 struct request_queue
*q
)
434 struct list_head
*ent
;
435 struct blkcg_gq
*blkg
;
438 * Determine the current blkg list_head. The first entry is
439 * root_rl which is off @q->blkg_list and mapped to the head.
441 if (rl
== &q
->root_rl
) {
443 /* There are no more block groups, hence no request lists */
447 blkg
= container_of(rl
, struct blkcg_gq
, rl
);
451 /* walk to the next list_head, skip root blkcg */
453 if (ent
== &q
->root_blkg
->q_node
)
455 if (ent
== &q
->blkg_list
)
458 blkg
= container_of(ent
, struct blkcg_gq
, q_node
);
462 static int blkcg_reset_stats(struct cgroup_subsys_state
*css
,
463 struct cftype
*cftype
, u64 val
)
465 struct blkcg
*blkcg
= css_to_blkcg(css
);
466 struct blkcg_gq
*blkg
;
469 mutex_lock(&blkcg_pol_mutex
);
470 spin_lock_irq(&blkcg
->lock
);
473 * Note that stat reset is racy - it doesn't synchronize against
474 * stat updates. This is a debug feature which shouldn't exist
475 * anyway. If you get hit by a race, retry.
477 hlist_for_each_entry(blkg
, &blkcg
->blkg_list
, blkcg_node
) {
478 for (i
= 0; i
< BLKCG_MAX_POLS
; i
++) {
479 struct blkcg_policy
*pol
= blkcg_policy
[i
];
481 if (blkcg_policy_enabled(blkg
->q
, pol
) &&
482 pol
->pd_reset_stats_fn
)
483 pol
->pd_reset_stats_fn(blkg
);
487 spin_unlock_irq(&blkcg
->lock
);
488 mutex_unlock(&blkcg_pol_mutex
);
492 static const char *blkg_dev_name(struct blkcg_gq
*blkg
)
494 /* some drivers (floppy) instantiate a queue w/o disk registered */
495 if (blkg
->q
->backing_dev_info
.dev
)
496 return dev_name(blkg
->q
->backing_dev_info
.dev
);
501 * blkcg_print_blkgs - helper for printing per-blkg data
502 * @sf: seq_file to print to
503 * @blkcg: blkcg of interest
504 * @prfill: fill function to print out a blkg
505 * @pol: policy in question
506 * @data: data to be passed to @prfill
507 * @show_total: to print out sum of prfill return values or not
509 * This function invokes @prfill on each blkg of @blkcg if pd for the
510 * policy specified by @pol exists. @prfill is invoked with @sf, the
511 * policy data and @data and the matching queue lock held. If @show_total
512 * is %true, the sum of the return values from @prfill is printed with
513 * "Total" label at the end.
515 * This is to be used to construct print functions for
516 * cftype->read_seq_string method.
518 void blkcg_print_blkgs(struct seq_file
*sf
, struct blkcg
*blkcg
,
519 u64 (*prfill
)(struct seq_file
*,
520 struct blkg_policy_data
*, int),
521 const struct blkcg_policy
*pol
, int data
,
524 struct blkcg_gq
*blkg
;
528 hlist_for_each_entry_rcu(blkg
, &blkcg
->blkg_list
, blkcg_node
) {
529 spin_lock_irq(blkg
->q
->queue_lock
);
530 if (blkcg_policy_enabled(blkg
->q
, pol
))
531 total
+= prfill(sf
, blkg
->pd
[pol
->plid
], data
);
532 spin_unlock_irq(blkg
->q
->queue_lock
);
537 seq_printf(sf
, "Total %llu\n", (unsigned long long)total
);
539 EXPORT_SYMBOL_GPL(blkcg_print_blkgs
);
542 * __blkg_prfill_u64 - prfill helper for a single u64 value
543 * @sf: seq_file to print to
544 * @pd: policy private data of interest
547 * Print @v to @sf for the device assocaited with @pd.
549 u64
__blkg_prfill_u64(struct seq_file
*sf
, struct blkg_policy_data
*pd
, u64 v
)
551 const char *dname
= blkg_dev_name(pd
->blkg
);
556 seq_printf(sf
, "%s %llu\n", dname
, (unsigned long long)v
);
559 EXPORT_SYMBOL_GPL(__blkg_prfill_u64
);
562 * __blkg_prfill_rwstat - prfill helper for a blkg_rwstat
563 * @sf: seq_file to print to
564 * @pd: policy private data of interest
565 * @rwstat: rwstat to print
567 * Print @rwstat to @sf for the device assocaited with @pd.
569 u64
__blkg_prfill_rwstat(struct seq_file
*sf
, struct blkg_policy_data
*pd
,
570 const struct blkg_rwstat
*rwstat
)
572 static const char *rwstr
[] = {
573 [BLKG_RWSTAT_READ
] = "Read",
574 [BLKG_RWSTAT_WRITE
] = "Write",
575 [BLKG_RWSTAT_SYNC
] = "Sync",
576 [BLKG_RWSTAT_ASYNC
] = "Async",
578 const char *dname
= blkg_dev_name(pd
->blkg
);
585 for (i
= 0; i
< BLKG_RWSTAT_NR
; i
++)
586 seq_printf(sf
, "%s %s %llu\n", dname
, rwstr
[i
],
587 (unsigned long long)rwstat
->cnt
[i
]);
589 v
= rwstat
->cnt
[BLKG_RWSTAT_READ
] + rwstat
->cnt
[BLKG_RWSTAT_WRITE
];
590 seq_printf(sf
, "%s Total %llu\n", dname
, (unsigned long long)v
);
593 EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat
);
596 * blkg_prfill_stat - prfill callback for blkg_stat
597 * @sf: seq_file to print to
598 * @pd: policy private data of interest
599 * @off: offset to the blkg_stat in @pd
601 * prfill callback for printing a blkg_stat.
603 u64
blkg_prfill_stat(struct seq_file
*sf
, struct blkg_policy_data
*pd
, int off
)
605 return __blkg_prfill_u64(sf
, pd
, blkg_stat_read((void *)pd
+ off
));
607 EXPORT_SYMBOL_GPL(blkg_prfill_stat
);
610 * blkg_prfill_rwstat - prfill callback for blkg_rwstat
611 * @sf: seq_file to print to
612 * @pd: policy private data of interest
613 * @off: offset to the blkg_rwstat in @pd
615 * prfill callback for printing a blkg_rwstat.
617 u64
blkg_prfill_rwstat(struct seq_file
*sf
, struct blkg_policy_data
*pd
,
620 struct blkg_rwstat rwstat
= blkg_rwstat_read((void *)pd
+ off
);
622 return __blkg_prfill_rwstat(sf
, pd
, &rwstat
);
624 EXPORT_SYMBOL_GPL(blkg_prfill_rwstat
);
627 * blkg_stat_recursive_sum - collect hierarchical blkg_stat
628 * @pd: policy private data of interest
629 * @off: offset to the blkg_stat in @pd
631 * Collect the blkg_stat specified by @off from @pd and all its online
632 * descendants and return the sum. The caller must be holding the queue
633 * lock for online tests.
635 u64
blkg_stat_recursive_sum(struct blkg_policy_data
*pd
, int off
)
637 struct blkcg_policy
*pol
= blkcg_policy
[pd
->plid
];
638 struct blkcg_gq
*pos_blkg
;
639 struct cgroup_subsys_state
*pos_css
;
642 lockdep_assert_held(pd
->blkg
->q
->queue_lock
);
645 blkg_for_each_descendant_pre(pos_blkg
, pos_css
, pd_to_blkg(pd
)) {
646 struct blkg_policy_data
*pos_pd
= blkg_to_pd(pos_blkg
, pol
);
647 struct blkg_stat
*stat
= (void *)pos_pd
+ off
;
649 if (pos_blkg
->online
)
650 sum
+= blkg_stat_read(stat
);
656 EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum
);
659 * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat
660 * @pd: policy private data of interest
661 * @off: offset to the blkg_stat in @pd
663 * Collect the blkg_rwstat specified by @off from @pd and all its online
664 * descendants and return the sum. The caller must be holding the queue
665 * lock for online tests.
667 struct blkg_rwstat
blkg_rwstat_recursive_sum(struct blkg_policy_data
*pd
,
670 struct blkcg_policy
*pol
= blkcg_policy
[pd
->plid
];
671 struct blkcg_gq
*pos_blkg
;
672 struct cgroup_subsys_state
*pos_css
;
673 struct blkg_rwstat sum
= { };
676 lockdep_assert_held(pd
->blkg
->q
->queue_lock
);
679 blkg_for_each_descendant_pre(pos_blkg
, pos_css
, pd_to_blkg(pd
)) {
680 struct blkg_policy_data
*pos_pd
= blkg_to_pd(pos_blkg
, pol
);
681 struct blkg_rwstat
*rwstat
= (void *)pos_pd
+ off
;
682 struct blkg_rwstat tmp
;
684 if (!pos_blkg
->online
)
687 tmp
= blkg_rwstat_read(rwstat
);
689 for (i
= 0; i
< BLKG_RWSTAT_NR
; i
++)
690 sum
.cnt
[i
] += tmp
.cnt
[i
];
696 EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum
);
699 * blkg_conf_prep - parse and prepare for per-blkg config update
700 * @blkcg: target block cgroup
701 * @pol: target policy
702 * @input: input string
703 * @ctx: blkg_conf_ctx to be filled
705 * Parse per-blkg config update from @input and initialize @ctx with the
706 * result. @ctx->blkg points to the blkg to be updated and @ctx->v the new
707 * value. This function returns with RCU read lock and queue lock held and
708 * must be paired with blkg_conf_finish().
710 int blkg_conf_prep(struct blkcg
*blkcg
, const struct blkcg_policy
*pol
,
711 const char *input
, struct blkg_conf_ctx
*ctx
)
712 __acquires(rcu
) __acquires(disk
->queue
->queue_lock
)
714 struct gendisk
*disk
;
715 struct blkcg_gq
*blkg
;
716 unsigned int major
, minor
;
717 unsigned long long v
;
720 if (sscanf(input
, "%u:%u %llu", &major
, &minor
, &v
) != 3)
723 disk
= get_gendisk(MKDEV(major
, minor
), &part
);
732 spin_lock_irq(disk
->queue
->queue_lock
);
734 if (blkcg_policy_enabled(disk
->queue
, pol
))
735 blkg
= blkg_lookup_create(blkcg
, disk
->queue
);
737 blkg
= ERR_PTR(-EINVAL
);
742 spin_unlock_irq(disk
->queue
->queue_lock
);
745 * If queue was bypassing, we should retry. Do so after a
746 * short msleep(). It isn't strictly necessary but queue
747 * can be bypassing for some time and it's always nice to
748 * avoid busy looping.
752 ret
= restart_syscall();
762 EXPORT_SYMBOL_GPL(blkg_conf_prep
);
765 * blkg_conf_finish - finish up per-blkg config update
766 * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep()
768 * Finish up after per-blkg config update. This function must be paired
769 * with blkg_conf_prep().
771 void blkg_conf_finish(struct blkg_conf_ctx
*ctx
)
772 __releases(ctx
->disk
->queue
->queue_lock
) __releases(rcu
)
774 spin_unlock_irq(ctx
->disk
->queue
->queue_lock
);
778 EXPORT_SYMBOL_GPL(blkg_conf_finish
);
780 struct cftype blkcg_files
[] = {
782 .name
= "reset_stats",
783 .write_u64
= blkcg_reset_stats
,
789 * blkcg_css_offline - cgroup css_offline callback
790 * @css: css of interest
792 * This function is called when @css is about to go away and responsible
793 * for shooting down all blkgs associated with @css. blkgs should be
794 * removed while holding both q and blkcg locks. As blkcg lock is nested
795 * inside q lock, this function performs reverse double lock dancing.
797 * This is the blkcg counterpart of ioc_release_fn().
799 static void blkcg_css_offline(struct cgroup_subsys_state
*css
)
801 struct blkcg
*blkcg
= css_to_blkcg(css
);
803 spin_lock_irq(&blkcg
->lock
);
805 while (!hlist_empty(&blkcg
->blkg_list
)) {
806 struct blkcg_gq
*blkg
= hlist_entry(blkcg
->blkg_list
.first
,
807 struct blkcg_gq
, blkcg_node
);
808 struct request_queue
*q
= blkg
->q
;
810 if (spin_trylock(q
->queue_lock
)) {
812 spin_unlock(q
->queue_lock
);
814 spin_unlock_irq(&blkcg
->lock
);
816 spin_lock_irq(&blkcg
->lock
);
820 spin_unlock_irq(&blkcg
->lock
);
822 wb_blkcg_offline(blkcg
);
825 static void blkcg_css_free(struct cgroup_subsys_state
*css
)
827 struct blkcg
*blkcg
= css_to_blkcg(css
);
829 mutex_lock(&blkcg_pol_mutex
);
830 list_del(&blkcg
->all_blkcgs_node
);
831 mutex_unlock(&blkcg_pol_mutex
);
833 if (blkcg
!= &blkcg_root
) {
836 for (i
= 0; i
< BLKCG_MAX_POLS
; i
++)
842 static struct cgroup_subsys_state
*
843 blkcg_css_alloc(struct cgroup_subsys_state
*parent_css
)
846 struct cgroup_subsys_state
*ret
;
849 mutex_lock(&blkcg_pol_mutex
);
856 blkcg
= kzalloc(sizeof(*blkcg
), GFP_KERNEL
);
858 ret
= ERR_PTR(-ENOMEM
);
862 for (i
= 0; i
< BLKCG_MAX_POLS
; i
++) {
863 struct blkcg_policy
*pol
= blkcg_policy
[i
];
864 struct blkcg_policy_data
*cpd
;
867 * If the policy hasn't been attached yet, wait for it
868 * to be attached before doing anything else. Otherwise,
869 * check if the policy requires any specific per-cgroup
870 * data: if it does, allocate and initialize it.
872 if (!pol
|| !pol
->cpd_size
)
875 BUG_ON(blkcg
->pd
[i
]);
876 cpd
= kzalloc(pol
->cpd_size
, GFP_KERNEL
);
878 ret
= ERR_PTR(-ENOMEM
);
883 pol
->cpd_init_fn(blkcg
);
887 spin_lock_init(&blkcg
->lock
);
888 INIT_RADIX_TREE(&blkcg
->blkg_tree
, GFP_ATOMIC
);
889 INIT_HLIST_HEAD(&blkcg
->blkg_list
);
890 #ifdef CONFIG_CGROUP_WRITEBACK
891 INIT_LIST_HEAD(&blkcg
->cgwb_list
);
893 list_add_tail(&blkcg
->all_blkcgs_node
, &all_blkcgs
);
895 mutex_unlock(&blkcg_pol_mutex
);
899 for (i
--; i
>= 0; i
--)
903 mutex_unlock(&blkcg_pol_mutex
);
908 * blkcg_init_queue - initialize blkcg part of request queue
909 * @q: request_queue to initialize
911 * Called from blk_alloc_queue_node(). Responsible for initializing blkcg
912 * part of new request_queue @q.
915 * 0 on success, -errno on failure.
917 int blkcg_init_queue(struct request_queue
*q
)
919 struct blkcg_gq
*new_blkg
, *blkg
;
923 new_blkg
= blkg_alloc(&blkcg_root
, q
, GFP_KERNEL
);
927 preloaded
= !radix_tree_preload(GFP_KERNEL
);
930 * Make sure the root blkg exists and count the existing blkgs. As
931 * @q is bypassing at this point, blkg_lookup_create() can't be
932 * used. Open code insertion.
935 spin_lock_irq(q
->queue_lock
);
936 blkg
= blkg_create(&blkcg_root
, q
, new_blkg
);
937 spin_unlock_irq(q
->queue_lock
);
941 radix_tree_preload_end();
945 return PTR_ERR(blkg
);
949 q
->root_rl
.blkg
= blkg
;
951 ret
= blk_throtl_init(q
);
953 spin_lock_irq(q
->queue_lock
);
955 spin_unlock_irq(q
->queue_lock
);
961 * blkcg_drain_queue - drain blkcg part of request_queue
962 * @q: request_queue to drain
964 * Called from blk_drain_queue(). Responsible for draining blkcg part.
966 void blkcg_drain_queue(struct request_queue
*q
)
968 lockdep_assert_held(q
->queue_lock
);
971 * @q could be exiting and already have destroyed all blkgs as
972 * indicated by NULL root_blkg. If so, don't confuse policies.
981 * blkcg_exit_queue - exit and release blkcg part of request_queue
982 * @q: request_queue being released
984 * Called from blk_release_queue(). Responsible for exiting blkcg part.
986 void blkcg_exit_queue(struct request_queue
*q
)
988 spin_lock_irq(q
->queue_lock
);
990 spin_unlock_irq(q
->queue_lock
);
996 * We cannot support shared io contexts, as we have no mean to support
997 * two tasks with the same ioc in two different groups without major rework
998 * of the main cic data structures. For now we allow a task to change
999 * its cgroup only if it's the only owner of its ioc.
1001 static int blkcg_can_attach(struct cgroup_subsys_state
*css
,
1002 struct cgroup_taskset
*tset
)
1004 struct task_struct
*task
;
1005 struct io_context
*ioc
;
1008 /* task_lock() is needed to avoid races with exit_io_context() */
1009 cgroup_taskset_for_each(task
, tset
) {
1011 ioc
= task
->io_context
;
1012 if (ioc
&& atomic_read(&ioc
->nr_tasks
) > 1)
1021 struct cgroup_subsys blkio_cgrp_subsys
= {
1022 .css_alloc
= blkcg_css_alloc
,
1023 .css_offline
= blkcg_css_offline
,
1024 .css_free
= blkcg_css_free
,
1025 .can_attach
= blkcg_can_attach
,
1026 .legacy_cftypes
= blkcg_files
,
1029 * This ensures that, if available, memcg is automatically enabled
1030 * together on the default hierarchy so that the owner cgroup can
1031 * be retrieved from writeback pages.
1033 .depends_on
= 1 << memory_cgrp_id
,
1036 EXPORT_SYMBOL_GPL(blkio_cgrp_subsys
);
1039 * blkcg_activate_policy - activate a blkcg policy on a request_queue
1040 * @q: request_queue of interest
1041 * @pol: blkcg policy to activate
1043 * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through
1044 * bypass mode to populate its blkgs with policy_data for @pol.
1046 * Activation happens with @q bypassed, so nobody would be accessing blkgs
1047 * from IO path. Update of each blkg is protected by both queue and blkcg
1048 * locks so that holding either lock and testing blkcg_policy_enabled() is
1049 * always enough for dereferencing policy data.
1051 * The caller is responsible for synchronizing [de]activations and policy
1052 * [un]registerations. Returns 0 on success, -errno on failure.
1054 int blkcg_activate_policy(struct request_queue
*q
,
1055 const struct blkcg_policy
*pol
)
1058 struct blkcg_gq
*blkg
;
1059 struct blkg_policy_data
*pd
, *nd
;
1062 if (blkcg_policy_enabled(q
, pol
))
1065 /* count and allocate policy_data for all existing blkgs */
1066 blk_queue_bypass_start(q
);
1067 spin_lock_irq(q
->queue_lock
);
1068 list_for_each_entry(blkg
, &q
->blkg_list
, q_node
)
1070 spin_unlock_irq(q
->queue_lock
);
1072 /* allocate per-blkg policy data for all existing blkgs */
1074 pd
= kzalloc_node(pol
->pd_size
, GFP_KERNEL
, q
->node
);
1079 list_add_tail(&pd
->alloc_node
, &pds
);
1083 * Install the allocated pds and cpds. With @q bypassing, no new blkg
1084 * should have been created while the queue lock was dropped.
1086 spin_lock_irq(q
->queue_lock
);
1088 list_for_each_entry(blkg
, &q
->blkg_list
, q_node
) {
1089 if (WARN_ON(list_empty(&pds
))) {
1090 /* umm... this shouldn't happen, just abort */
1094 pd
= list_first_entry(&pds
, struct blkg_policy_data
, alloc_node
);
1095 list_del_init(&pd
->alloc_node
);
1097 /* grab blkcg lock too while installing @pd on @blkg */
1098 spin_lock(&blkg
->blkcg
->lock
);
1100 blkg
->pd
[pol
->plid
] = pd
;
1102 pd
->plid
= pol
->plid
;
1103 pol
->pd_init_fn(blkg
);
1105 spin_unlock(&blkg
->blkcg
->lock
);
1108 __set_bit(pol
->plid
, q
->blkcg_pols
);
1111 spin_unlock_irq(q
->queue_lock
);
1113 blk_queue_bypass_end(q
);
1114 list_for_each_entry_safe(pd
, nd
, &pds
, alloc_node
)
1118 EXPORT_SYMBOL_GPL(blkcg_activate_policy
);
1121 * blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue
1122 * @q: request_queue of interest
1123 * @pol: blkcg policy to deactivate
1125 * Deactivate @pol on @q. Follows the same synchronization rules as
1126 * blkcg_activate_policy().
1128 void blkcg_deactivate_policy(struct request_queue
*q
,
1129 const struct blkcg_policy
*pol
)
1131 struct blkcg_gq
*blkg
;
1133 if (!blkcg_policy_enabled(q
, pol
))
1136 blk_queue_bypass_start(q
);
1137 spin_lock_irq(q
->queue_lock
);
1139 __clear_bit(pol
->plid
, q
->blkcg_pols
);
1141 list_for_each_entry(blkg
, &q
->blkg_list
, q_node
) {
1142 /* grab blkcg lock too while removing @pd from @blkg */
1143 spin_lock(&blkg
->blkcg
->lock
);
1145 if (pol
->pd_offline_fn
)
1146 pol
->pd_offline_fn(blkg
);
1147 if (pol
->pd_exit_fn
)
1148 pol
->pd_exit_fn(blkg
);
1150 kfree(blkg
->pd
[pol
->plid
]);
1151 blkg
->pd
[pol
->plid
] = NULL
;
1153 spin_unlock(&blkg
->blkcg
->lock
);
1156 spin_unlock_irq(q
->queue_lock
);
1157 blk_queue_bypass_end(q
);
1159 EXPORT_SYMBOL_GPL(blkcg_deactivate_policy
);
1162 * blkcg_policy_register - register a blkcg policy
1163 * @pol: blkcg policy to register
1165 * Register @pol with blkcg core. Might sleep and @pol may be modified on
1166 * successful registration. Returns 0 on success and -errno on failure.
1168 int blkcg_policy_register(struct blkcg_policy
*pol
)
1170 struct blkcg
*blkcg
;
1173 if (WARN_ON(pol
->pd_size
< sizeof(struct blkg_policy_data
)))
1176 mutex_lock(&blkcg_pol_register_mutex
);
1177 mutex_lock(&blkcg_pol_mutex
);
1179 /* find an empty slot */
1181 for (i
= 0; i
< BLKCG_MAX_POLS
; i
++)
1182 if (!blkcg_policy
[i
])
1184 if (i
>= BLKCG_MAX_POLS
)
1189 blkcg_policy
[pol
->plid
] = pol
;
1191 /* allocate and install cpd's */
1192 if (pol
->cpd_size
) {
1193 list_for_each_entry(blkcg
, &all_blkcgs
, all_blkcgs_node
) {
1194 struct blkcg_policy_data
*cpd
;
1196 cpd
= kzalloc(pol
->cpd_size
, GFP_KERNEL
);
1198 mutex_unlock(&blkcg_pol_mutex
);
1202 blkcg
->pd
[pol
->plid
] = cpd
;
1203 cpd
->plid
= pol
->plid
;
1204 pol
->cpd_init_fn(blkcg
);
1208 mutex_unlock(&blkcg_pol_mutex
);
1210 /* everything is in place, add intf files for the new policy */
1212 WARN_ON(cgroup_add_legacy_cftypes(&blkio_cgrp_subsys
,
1214 mutex_unlock(&blkcg_pol_register_mutex
);
1218 if (pol
->cpd_size
) {
1219 list_for_each_entry(blkcg
, &all_blkcgs
, all_blkcgs_node
) {
1220 kfree(blkcg
->pd
[pol
->plid
]);
1221 blkcg
->pd
[pol
->plid
] = NULL
;
1224 blkcg_policy
[pol
->plid
] = NULL
;
1226 mutex_unlock(&blkcg_pol_mutex
);
1227 mutex_unlock(&blkcg_pol_register_mutex
);
1230 EXPORT_SYMBOL_GPL(blkcg_policy_register
);
1233 * blkcg_policy_unregister - unregister a blkcg policy
1234 * @pol: blkcg policy to unregister
1236 * Undo blkcg_policy_register(@pol). Might sleep.
1238 void blkcg_policy_unregister(struct blkcg_policy
*pol
)
1240 struct blkcg
*blkcg
;
1242 mutex_lock(&blkcg_pol_register_mutex
);
1244 if (WARN_ON(blkcg_policy
[pol
->plid
] != pol
))
1247 /* kill the intf files first */
1249 cgroup_rm_cftypes(pol
->cftypes
);
1251 /* remove cpds and unregister */
1252 mutex_lock(&blkcg_pol_mutex
);
1254 if (pol
->cpd_size
) {
1255 list_for_each_entry(blkcg
, &all_blkcgs
, all_blkcgs_node
) {
1256 kfree(blkcg
->pd
[pol
->plid
]);
1257 blkcg
->pd
[pol
->plid
] = NULL
;
1260 blkcg_policy
[pol
->plid
] = NULL
;
1262 mutex_unlock(&blkcg_pol_mutex
);
1264 mutex_unlock(&blkcg_pol_register_mutex
);
1266 EXPORT_SYMBOL_GPL(blkcg_policy_unregister
);