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
);
393 * A group is RCU protected, but having an rcu lock does not mean that one
394 * can access all the fields of blkg and assume these are valid. For
395 * example, don't try to follow throtl_data and request queue links.
397 * Having a reference to blkg under an rcu allows accesses to only values
398 * local to groups like group stats and group rate limits.
400 void __blkg_release_rcu(struct rcu_head
*rcu_head
)
402 struct blkcg_gq
*blkg
= container_of(rcu_head
, struct blkcg_gq
, rcu_head
);
405 /* tell policies that this one is being freed */
406 for (i
= 0; i
< BLKCG_MAX_POLS
; i
++) {
407 struct blkcg_policy
*pol
= blkcg_policy
[i
];
409 if (blkg
->pd
[i
] && pol
->pd_exit_fn
)
410 pol
->pd_exit_fn(blkg
);
413 /* release the blkcg and parent blkg refs this blkg has been holding */
414 css_put(&blkg
->blkcg
->css
);
416 blkg_put(blkg
->parent
);
418 wb_congested_put(blkg
->wb_congested
);
422 EXPORT_SYMBOL_GPL(__blkg_release_rcu
);
425 * The next function used by blk_queue_for_each_rl(). It's a bit tricky
426 * because the root blkg uses @q->root_rl instead of its own rl.
428 struct request_list
*__blk_queue_next_rl(struct request_list
*rl
,
429 struct request_queue
*q
)
431 struct list_head
*ent
;
432 struct blkcg_gq
*blkg
;
435 * Determine the current blkg list_head. The first entry is
436 * root_rl which is off @q->blkg_list and mapped to the head.
438 if (rl
== &q
->root_rl
) {
440 /* There are no more block groups, hence no request lists */
444 blkg
= container_of(rl
, struct blkcg_gq
, rl
);
448 /* walk to the next list_head, skip root blkcg */
450 if (ent
== &q
->root_blkg
->q_node
)
452 if (ent
== &q
->blkg_list
)
455 blkg
= container_of(ent
, struct blkcg_gq
, q_node
);
459 static int blkcg_reset_stats(struct cgroup_subsys_state
*css
,
460 struct cftype
*cftype
, u64 val
)
462 struct blkcg
*blkcg
= css_to_blkcg(css
);
463 struct blkcg_gq
*blkg
;
466 mutex_lock(&blkcg_pol_mutex
);
467 spin_lock_irq(&blkcg
->lock
);
470 * Note that stat reset is racy - it doesn't synchronize against
471 * stat updates. This is a debug feature which shouldn't exist
472 * anyway. If you get hit by a race, retry.
474 hlist_for_each_entry(blkg
, &blkcg
->blkg_list
, blkcg_node
) {
475 for (i
= 0; i
< BLKCG_MAX_POLS
; i
++) {
476 struct blkcg_policy
*pol
= blkcg_policy
[i
];
478 if (blkcg_policy_enabled(blkg
->q
, pol
) &&
479 pol
->pd_reset_stats_fn
)
480 pol
->pd_reset_stats_fn(blkg
);
484 spin_unlock_irq(&blkcg
->lock
);
485 mutex_unlock(&blkcg_pol_mutex
);
489 static const char *blkg_dev_name(struct blkcg_gq
*blkg
)
491 /* some drivers (floppy) instantiate a queue w/o disk registered */
492 if (blkg
->q
->backing_dev_info
.dev
)
493 return dev_name(blkg
->q
->backing_dev_info
.dev
);
498 * blkcg_print_blkgs - helper for printing per-blkg data
499 * @sf: seq_file to print to
500 * @blkcg: blkcg of interest
501 * @prfill: fill function to print out a blkg
502 * @pol: policy in question
503 * @data: data to be passed to @prfill
504 * @show_total: to print out sum of prfill return values or not
506 * This function invokes @prfill on each blkg of @blkcg if pd for the
507 * policy specified by @pol exists. @prfill is invoked with @sf, the
508 * policy data and @data and the matching queue lock held. If @show_total
509 * is %true, the sum of the return values from @prfill is printed with
510 * "Total" label at the end.
512 * This is to be used to construct print functions for
513 * cftype->read_seq_string method.
515 void blkcg_print_blkgs(struct seq_file
*sf
, struct blkcg
*blkcg
,
516 u64 (*prfill
)(struct seq_file
*,
517 struct blkg_policy_data
*, int),
518 const struct blkcg_policy
*pol
, int data
,
521 struct blkcg_gq
*blkg
;
525 hlist_for_each_entry_rcu(blkg
, &blkcg
->blkg_list
, blkcg_node
) {
526 spin_lock_irq(blkg
->q
->queue_lock
);
527 if (blkcg_policy_enabled(blkg
->q
, pol
))
528 total
+= prfill(sf
, blkg
->pd
[pol
->plid
], data
);
529 spin_unlock_irq(blkg
->q
->queue_lock
);
534 seq_printf(sf
, "Total %llu\n", (unsigned long long)total
);
536 EXPORT_SYMBOL_GPL(blkcg_print_blkgs
);
539 * __blkg_prfill_u64 - prfill helper for a single u64 value
540 * @sf: seq_file to print to
541 * @pd: policy private data of interest
544 * Print @v to @sf for the device assocaited with @pd.
546 u64
__blkg_prfill_u64(struct seq_file
*sf
, struct blkg_policy_data
*pd
, u64 v
)
548 const char *dname
= blkg_dev_name(pd
->blkg
);
553 seq_printf(sf
, "%s %llu\n", dname
, (unsigned long long)v
);
556 EXPORT_SYMBOL_GPL(__blkg_prfill_u64
);
559 * __blkg_prfill_rwstat - prfill helper for a blkg_rwstat
560 * @sf: seq_file to print to
561 * @pd: policy private data of interest
562 * @rwstat: rwstat to print
564 * Print @rwstat to @sf for the device assocaited with @pd.
566 u64
__blkg_prfill_rwstat(struct seq_file
*sf
, struct blkg_policy_data
*pd
,
567 const struct blkg_rwstat
*rwstat
)
569 static const char *rwstr
[] = {
570 [BLKG_RWSTAT_READ
] = "Read",
571 [BLKG_RWSTAT_WRITE
] = "Write",
572 [BLKG_RWSTAT_SYNC
] = "Sync",
573 [BLKG_RWSTAT_ASYNC
] = "Async",
575 const char *dname
= blkg_dev_name(pd
->blkg
);
582 for (i
= 0; i
< BLKG_RWSTAT_NR
; i
++)
583 seq_printf(sf
, "%s %s %llu\n", dname
, rwstr
[i
],
584 (unsigned long long)rwstat
->cnt
[i
]);
586 v
= rwstat
->cnt
[BLKG_RWSTAT_READ
] + rwstat
->cnt
[BLKG_RWSTAT_WRITE
];
587 seq_printf(sf
, "%s Total %llu\n", dname
, (unsigned long long)v
);
590 EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat
);
593 * blkg_prfill_stat - prfill callback for blkg_stat
594 * @sf: seq_file to print to
595 * @pd: policy private data of interest
596 * @off: offset to the blkg_stat in @pd
598 * prfill callback for printing a blkg_stat.
600 u64
blkg_prfill_stat(struct seq_file
*sf
, struct blkg_policy_data
*pd
, int off
)
602 return __blkg_prfill_u64(sf
, pd
, blkg_stat_read((void *)pd
+ off
));
604 EXPORT_SYMBOL_GPL(blkg_prfill_stat
);
607 * blkg_prfill_rwstat - prfill callback for blkg_rwstat
608 * @sf: seq_file to print to
609 * @pd: policy private data of interest
610 * @off: offset to the blkg_rwstat in @pd
612 * prfill callback for printing a blkg_rwstat.
614 u64
blkg_prfill_rwstat(struct seq_file
*sf
, struct blkg_policy_data
*pd
,
617 struct blkg_rwstat rwstat
= blkg_rwstat_read((void *)pd
+ off
);
619 return __blkg_prfill_rwstat(sf
, pd
, &rwstat
);
621 EXPORT_SYMBOL_GPL(blkg_prfill_rwstat
);
624 * blkg_stat_recursive_sum - collect hierarchical blkg_stat
625 * @pd: policy private data of interest
626 * @off: offset to the blkg_stat in @pd
628 * Collect the blkg_stat specified by @off from @pd and all its online
629 * descendants and return the sum. The caller must be holding the queue
630 * lock for online tests.
632 u64
blkg_stat_recursive_sum(struct blkg_policy_data
*pd
, int off
)
634 struct blkcg_policy
*pol
= blkcg_policy
[pd
->plid
];
635 struct blkcg_gq
*pos_blkg
;
636 struct cgroup_subsys_state
*pos_css
;
639 lockdep_assert_held(pd
->blkg
->q
->queue_lock
);
642 blkg_for_each_descendant_pre(pos_blkg
, pos_css
, pd_to_blkg(pd
)) {
643 struct blkg_policy_data
*pos_pd
= blkg_to_pd(pos_blkg
, pol
);
644 struct blkg_stat
*stat
= (void *)pos_pd
+ off
;
646 if (pos_blkg
->online
)
647 sum
+= blkg_stat_read(stat
);
653 EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum
);
656 * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat
657 * @pd: policy private data of interest
658 * @off: offset to the blkg_stat in @pd
660 * Collect the blkg_rwstat specified by @off from @pd and all its online
661 * descendants and return the sum. The caller must be holding the queue
662 * lock for online tests.
664 struct blkg_rwstat
blkg_rwstat_recursive_sum(struct blkg_policy_data
*pd
,
667 struct blkcg_policy
*pol
= blkcg_policy
[pd
->plid
];
668 struct blkcg_gq
*pos_blkg
;
669 struct cgroup_subsys_state
*pos_css
;
670 struct blkg_rwstat sum
= { };
673 lockdep_assert_held(pd
->blkg
->q
->queue_lock
);
676 blkg_for_each_descendant_pre(pos_blkg
, pos_css
, pd_to_blkg(pd
)) {
677 struct blkg_policy_data
*pos_pd
= blkg_to_pd(pos_blkg
, pol
);
678 struct blkg_rwstat
*rwstat
= (void *)pos_pd
+ off
;
679 struct blkg_rwstat tmp
;
681 if (!pos_blkg
->online
)
684 tmp
= blkg_rwstat_read(rwstat
);
686 for (i
= 0; i
< BLKG_RWSTAT_NR
; i
++)
687 sum
.cnt
[i
] += tmp
.cnt
[i
];
693 EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum
);
696 * blkg_conf_prep - parse and prepare for per-blkg config update
697 * @blkcg: target block cgroup
698 * @pol: target policy
699 * @input: input string
700 * @ctx: blkg_conf_ctx to be filled
702 * Parse per-blkg config update from @input and initialize @ctx with the
703 * result. @ctx->blkg points to the blkg to be updated and @ctx->v the new
704 * value. This function returns with RCU read lock and queue lock held and
705 * must be paired with blkg_conf_finish().
707 int blkg_conf_prep(struct blkcg
*blkcg
, const struct blkcg_policy
*pol
,
708 const char *input
, struct blkg_conf_ctx
*ctx
)
709 __acquires(rcu
) __acquires(disk
->queue
->queue_lock
)
711 struct gendisk
*disk
;
712 struct blkcg_gq
*blkg
;
713 unsigned int major
, minor
;
714 unsigned long long v
;
717 if (sscanf(input
, "%u:%u %llu", &major
, &minor
, &v
) != 3)
720 disk
= get_gendisk(MKDEV(major
, minor
), &part
);
725 spin_lock_irq(disk
->queue
->queue_lock
);
727 if (blkcg_policy_enabled(disk
->queue
, pol
))
728 blkg
= blkg_lookup_create(blkcg
, disk
->queue
);
730 blkg
= ERR_PTR(-EINVAL
);
735 spin_unlock_irq(disk
->queue
->queue_lock
);
738 * If queue was bypassing, we should retry. Do so after a
739 * short msleep(). It isn't strictly necessary but queue
740 * can be bypassing for some time and it's always nice to
741 * avoid busy looping.
745 ret
= restart_syscall();
755 EXPORT_SYMBOL_GPL(blkg_conf_prep
);
758 * blkg_conf_finish - finish up per-blkg config update
759 * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep()
761 * Finish up after per-blkg config update. This function must be paired
762 * with blkg_conf_prep().
764 void blkg_conf_finish(struct blkg_conf_ctx
*ctx
)
765 __releases(ctx
->disk
->queue
->queue_lock
) __releases(rcu
)
767 spin_unlock_irq(ctx
->disk
->queue
->queue_lock
);
771 EXPORT_SYMBOL_GPL(blkg_conf_finish
);
773 struct cftype blkcg_files
[] = {
775 .name
= "reset_stats",
776 .write_u64
= blkcg_reset_stats
,
782 * blkcg_css_offline - cgroup css_offline callback
783 * @css: css of interest
785 * This function is called when @css is about to go away and responsible
786 * for shooting down all blkgs associated with @css. blkgs should be
787 * removed while holding both q and blkcg locks. As blkcg lock is nested
788 * inside q lock, this function performs reverse double lock dancing.
790 * This is the blkcg counterpart of ioc_release_fn().
792 static void blkcg_css_offline(struct cgroup_subsys_state
*css
)
794 struct blkcg
*blkcg
= css_to_blkcg(css
);
796 spin_lock_irq(&blkcg
->lock
);
798 while (!hlist_empty(&blkcg
->blkg_list
)) {
799 struct blkcg_gq
*blkg
= hlist_entry(blkcg
->blkg_list
.first
,
800 struct blkcg_gq
, blkcg_node
);
801 struct request_queue
*q
= blkg
->q
;
803 if (spin_trylock(q
->queue_lock
)) {
805 spin_unlock(q
->queue_lock
);
807 spin_unlock_irq(&blkcg
->lock
);
809 spin_lock_irq(&blkcg
->lock
);
813 spin_unlock_irq(&blkcg
->lock
);
815 wb_blkcg_offline(blkcg
);
818 static void blkcg_css_free(struct cgroup_subsys_state
*css
)
820 struct blkcg
*blkcg
= css_to_blkcg(css
);
822 mutex_lock(&blkcg_pol_mutex
);
823 list_del(&blkcg
->all_blkcgs_node
);
824 mutex_unlock(&blkcg_pol_mutex
);
826 if (blkcg
!= &blkcg_root
) {
829 for (i
= 0; i
< BLKCG_MAX_POLS
; i
++)
835 static struct cgroup_subsys_state
*
836 blkcg_css_alloc(struct cgroup_subsys_state
*parent_css
)
839 struct cgroup_subsys_state
*ret
;
842 mutex_lock(&blkcg_pol_mutex
);
849 blkcg
= kzalloc(sizeof(*blkcg
), GFP_KERNEL
);
851 ret
= ERR_PTR(-ENOMEM
);
855 for (i
= 0; i
< BLKCG_MAX_POLS
; i
++) {
856 struct blkcg_policy
*pol
= blkcg_policy
[i
];
857 struct blkcg_policy_data
*cpd
;
860 * If the policy hasn't been attached yet, wait for it
861 * to be attached before doing anything else. Otherwise,
862 * check if the policy requires any specific per-cgroup
863 * data: if it does, allocate and initialize it.
865 if (!pol
|| !pol
->cpd_size
)
868 BUG_ON(blkcg
->pd
[i
]);
869 cpd
= kzalloc(pol
->cpd_size
, GFP_KERNEL
);
871 ret
= ERR_PTR(-ENOMEM
);
876 pol
->cpd_init_fn(blkcg
);
880 spin_lock_init(&blkcg
->lock
);
881 INIT_RADIX_TREE(&blkcg
->blkg_tree
, GFP_ATOMIC
);
882 INIT_HLIST_HEAD(&blkcg
->blkg_list
);
883 #ifdef CONFIG_CGROUP_WRITEBACK
884 INIT_LIST_HEAD(&blkcg
->cgwb_list
);
886 list_add_tail(&blkcg
->all_blkcgs_node
, &all_blkcgs
);
888 mutex_unlock(&blkcg_pol_mutex
);
892 for (i
--; i
>= 0; i
--)
896 mutex_unlock(&blkcg_pol_mutex
);
901 * blkcg_init_queue - initialize blkcg part of request queue
902 * @q: request_queue to initialize
904 * Called from blk_alloc_queue_node(). Responsible for initializing blkcg
905 * part of new request_queue @q.
908 * 0 on success, -errno on failure.
910 int blkcg_init_queue(struct request_queue
*q
)
912 struct blkcg_gq
*new_blkg
, *blkg
;
916 new_blkg
= blkg_alloc(&blkcg_root
, q
, GFP_KERNEL
);
920 preloaded
= !radix_tree_preload(GFP_KERNEL
);
923 * Make sure the root blkg exists and count the existing blkgs. As
924 * @q is bypassing at this point, blkg_lookup_create() can't be
925 * used. Open code insertion.
928 spin_lock_irq(q
->queue_lock
);
929 blkg
= blkg_create(&blkcg_root
, q
, new_blkg
);
930 spin_unlock_irq(q
->queue_lock
);
934 radix_tree_preload_end();
938 return PTR_ERR(blkg
);
942 q
->root_rl
.blkg
= blkg
;
944 ret
= blk_throtl_init(q
);
946 spin_lock_irq(q
->queue_lock
);
948 spin_unlock_irq(q
->queue_lock
);
954 * blkcg_drain_queue - drain blkcg part of request_queue
955 * @q: request_queue to drain
957 * Called from blk_drain_queue(). Responsible for draining blkcg part.
959 void blkcg_drain_queue(struct request_queue
*q
)
961 lockdep_assert_held(q
->queue_lock
);
964 * @q could be exiting and already have destroyed all blkgs as
965 * indicated by NULL root_blkg. If so, don't confuse policies.
974 * blkcg_exit_queue - exit and release blkcg part of request_queue
975 * @q: request_queue being released
977 * Called from blk_release_queue(). Responsible for exiting blkcg part.
979 void blkcg_exit_queue(struct request_queue
*q
)
981 spin_lock_irq(q
->queue_lock
);
983 spin_unlock_irq(q
->queue_lock
);
989 * We cannot support shared io contexts, as we have no mean to support
990 * two tasks with the same ioc in two different groups without major rework
991 * of the main cic data structures. For now we allow a task to change
992 * its cgroup only if it's the only owner of its ioc.
994 static int blkcg_can_attach(struct cgroup_subsys_state
*css
,
995 struct cgroup_taskset
*tset
)
997 struct task_struct
*task
;
998 struct io_context
*ioc
;
1001 /* task_lock() is needed to avoid races with exit_io_context() */
1002 cgroup_taskset_for_each(task
, tset
) {
1004 ioc
= task
->io_context
;
1005 if (ioc
&& atomic_read(&ioc
->nr_tasks
) > 1)
1014 struct cgroup_subsys blkio_cgrp_subsys
= {
1015 .css_alloc
= blkcg_css_alloc
,
1016 .css_offline
= blkcg_css_offline
,
1017 .css_free
= blkcg_css_free
,
1018 .can_attach
= blkcg_can_attach
,
1019 .legacy_cftypes
= blkcg_files
,
1022 * This ensures that, if available, memcg is automatically enabled
1023 * together on the default hierarchy so that the owner cgroup can
1024 * be retrieved from writeback pages.
1026 .depends_on
= 1 << memory_cgrp_id
,
1029 EXPORT_SYMBOL_GPL(blkio_cgrp_subsys
);
1032 * blkcg_activate_policy - activate a blkcg policy on a request_queue
1033 * @q: request_queue of interest
1034 * @pol: blkcg policy to activate
1036 * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through
1037 * bypass mode to populate its blkgs with policy_data for @pol.
1039 * Activation happens with @q bypassed, so nobody would be accessing blkgs
1040 * from IO path. Update of each blkg is protected by both queue and blkcg
1041 * locks so that holding either lock and testing blkcg_policy_enabled() is
1042 * always enough for dereferencing policy data.
1044 * The caller is responsible for synchronizing [de]activations and policy
1045 * [un]registerations. Returns 0 on success, -errno on failure.
1047 int blkcg_activate_policy(struct request_queue
*q
,
1048 const struct blkcg_policy
*pol
)
1051 struct blkcg_gq
*blkg
;
1052 struct blkg_policy_data
*pd
, *nd
;
1055 if (blkcg_policy_enabled(q
, pol
))
1058 /* count and allocate policy_data for all existing blkgs */
1059 blk_queue_bypass_start(q
);
1060 spin_lock_irq(q
->queue_lock
);
1061 list_for_each_entry(blkg
, &q
->blkg_list
, q_node
)
1063 spin_unlock_irq(q
->queue_lock
);
1065 /* allocate per-blkg policy data for all existing blkgs */
1067 pd
= kzalloc_node(pol
->pd_size
, GFP_KERNEL
, q
->node
);
1072 list_add_tail(&pd
->alloc_node
, &pds
);
1076 * Install the allocated pds and cpds. With @q bypassing, no new blkg
1077 * should have been created while the queue lock was dropped.
1079 spin_lock_irq(q
->queue_lock
);
1081 list_for_each_entry(blkg
, &q
->blkg_list
, q_node
) {
1082 if (WARN_ON(list_empty(&pds
))) {
1083 /* umm... this shouldn't happen, just abort */
1087 pd
= list_first_entry(&pds
, struct blkg_policy_data
, alloc_node
);
1088 list_del_init(&pd
->alloc_node
);
1090 /* grab blkcg lock too while installing @pd on @blkg */
1091 spin_lock(&blkg
->blkcg
->lock
);
1093 blkg
->pd
[pol
->plid
] = pd
;
1095 pd
->plid
= pol
->plid
;
1096 pol
->pd_init_fn(blkg
);
1098 spin_unlock(&blkg
->blkcg
->lock
);
1101 __set_bit(pol
->plid
, q
->blkcg_pols
);
1104 spin_unlock_irq(q
->queue_lock
);
1106 blk_queue_bypass_end(q
);
1107 list_for_each_entry_safe(pd
, nd
, &pds
, alloc_node
)
1111 EXPORT_SYMBOL_GPL(blkcg_activate_policy
);
1114 * blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue
1115 * @q: request_queue of interest
1116 * @pol: blkcg policy to deactivate
1118 * Deactivate @pol on @q. Follows the same synchronization rules as
1119 * blkcg_activate_policy().
1121 void blkcg_deactivate_policy(struct request_queue
*q
,
1122 const struct blkcg_policy
*pol
)
1124 struct blkcg_gq
*blkg
;
1126 if (!blkcg_policy_enabled(q
, pol
))
1129 blk_queue_bypass_start(q
);
1130 spin_lock_irq(q
->queue_lock
);
1132 __clear_bit(pol
->plid
, q
->blkcg_pols
);
1134 list_for_each_entry(blkg
, &q
->blkg_list
, q_node
) {
1135 /* grab blkcg lock too while removing @pd from @blkg */
1136 spin_lock(&blkg
->blkcg
->lock
);
1138 if (pol
->pd_offline_fn
)
1139 pol
->pd_offline_fn(blkg
);
1140 if (pol
->pd_exit_fn
)
1141 pol
->pd_exit_fn(blkg
);
1143 kfree(blkg
->pd
[pol
->plid
]);
1144 blkg
->pd
[pol
->plid
] = NULL
;
1146 spin_unlock(&blkg
->blkcg
->lock
);
1149 spin_unlock_irq(q
->queue_lock
);
1150 blk_queue_bypass_end(q
);
1152 EXPORT_SYMBOL_GPL(blkcg_deactivate_policy
);
1155 * blkcg_policy_register - register a blkcg policy
1156 * @pol: blkcg policy to register
1158 * Register @pol with blkcg core. Might sleep and @pol may be modified on
1159 * successful registration. Returns 0 on success and -errno on failure.
1161 int blkcg_policy_register(struct blkcg_policy
*pol
)
1163 struct blkcg
*blkcg
;
1166 if (WARN_ON(pol
->pd_size
< sizeof(struct blkg_policy_data
)))
1169 mutex_lock(&blkcg_pol_register_mutex
);
1170 mutex_lock(&blkcg_pol_mutex
);
1172 /* find an empty slot */
1174 for (i
= 0; i
< BLKCG_MAX_POLS
; i
++)
1175 if (!blkcg_policy
[i
])
1177 if (i
>= BLKCG_MAX_POLS
)
1182 blkcg_policy
[pol
->plid
] = pol
;
1184 /* allocate and install cpd's */
1185 if (pol
->cpd_size
) {
1186 list_for_each_entry(blkcg
, &all_blkcgs
, all_blkcgs_node
) {
1187 struct blkcg_policy_data
*cpd
;
1189 cpd
= kzalloc(pol
->cpd_size
, GFP_KERNEL
);
1191 mutex_unlock(&blkcg_pol_mutex
);
1195 blkcg
->pd
[pol
->plid
] = cpd
;
1196 cpd
->plid
= pol
->plid
;
1197 pol
->cpd_init_fn(blkcg
);
1201 mutex_unlock(&blkcg_pol_mutex
);
1203 /* everything is in place, add intf files for the new policy */
1205 WARN_ON(cgroup_add_legacy_cftypes(&blkio_cgrp_subsys
,
1207 mutex_unlock(&blkcg_pol_register_mutex
);
1211 if (pol
->cpd_size
) {
1212 list_for_each_entry(blkcg
, &all_blkcgs
, all_blkcgs_node
) {
1213 kfree(blkcg
->pd
[pol
->plid
]);
1214 blkcg
->pd
[pol
->plid
] = NULL
;
1217 blkcg_policy
[pol
->plid
] = NULL
;
1219 mutex_unlock(&blkcg_pol_mutex
);
1220 mutex_unlock(&blkcg_pol_register_mutex
);
1223 EXPORT_SYMBOL_GPL(blkcg_policy_register
);
1226 * blkcg_policy_unregister - unregister a blkcg policy
1227 * @pol: blkcg policy to unregister
1229 * Undo blkcg_policy_register(@pol). Might sleep.
1231 void blkcg_policy_unregister(struct blkcg_policy
*pol
)
1233 struct blkcg
*blkcg
;
1235 mutex_lock(&blkcg_pol_register_mutex
);
1237 if (WARN_ON(blkcg_policy
[pol
->plid
] != pol
))
1240 /* kill the intf files first */
1242 cgroup_rm_cftypes(pol
->cftypes
);
1244 /* remove cpds and unregister */
1245 mutex_lock(&blkcg_pol_mutex
);
1247 if (pol
->cpd_size
) {
1248 list_for_each_entry(blkcg
, &all_blkcgs
, all_blkcgs_node
) {
1249 kfree(blkcg
->pd
[pol
->plid
]);
1250 blkcg
->pd
[pol
->plid
] = NULL
;
1253 blkcg_policy
[pol
->plid
] = NULL
;
1255 mutex_unlock(&blkcg_pol_mutex
);
1257 mutex_unlock(&blkcg_pol_register_mutex
);
1259 EXPORT_SYMBOL_GPL(blkcg_policy_unregister
);