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1 | /* | |
2 | * Common Block IO controller cgroup interface | |
3 | * | |
4 | * Based on ideas and code from CFQ, CFS and BFQ: | |
5 | * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> | |
6 | * | |
7 | * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> | |
8 | * Paolo Valente <paolo.valente@unimore.it> | |
9 | * | |
10 | * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com> | |
11 | * Nauman Rafique <nauman@google.com> | |
12 | */ | |
13 | #include <linux/ioprio.h> | |
14 | #include <linux/kdev_t.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/err.h> | |
17 | #include <linux/blkdev.h> | |
18 | #include <linux/slab.h> | |
19 | #include <linux/genhd.h> | |
20 | #include <linux/delay.h> | |
21 | #include <linux/atomic.h> | |
22 | #include "blk-cgroup.h" | |
23 | #include "blk.h" | |
24 | ||
25 | #define MAX_KEY_LEN 100 | |
26 | ||
27 | static DEFINE_MUTEX(blkcg_pol_mutex); | |
28 | ||
29 | struct blkcg blkcg_root = { .cfq_weight = 2 * CFQ_WEIGHT_DEFAULT, | |
30 | .cfq_leaf_weight = 2 * CFQ_WEIGHT_DEFAULT, }; | |
31 | EXPORT_SYMBOL_GPL(blkcg_root); | |
32 | ||
33 | static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS]; | |
34 | ||
35 | static bool blkcg_policy_enabled(struct request_queue *q, | |
36 | const struct blkcg_policy *pol) | |
37 | { | |
38 | return pol && test_bit(pol->plid, q->blkcg_pols); | |
39 | } | |
40 | ||
41 | /** | |
42 | * blkg_free - free a blkg | |
43 | * @blkg: blkg to free | |
44 | * | |
45 | * Free @blkg which may be partially allocated. | |
46 | */ | |
47 | static void blkg_free(struct blkcg_gq *blkg) | |
48 | { | |
49 | int i; | |
50 | ||
51 | if (!blkg) | |
52 | return; | |
53 | ||
54 | for (i = 0; i < BLKCG_MAX_POLS; i++) | |
55 | kfree(blkg->pd[i]); | |
56 | ||
57 | blk_exit_rl(&blkg->rl); | |
58 | kfree(blkg); | |
59 | } | |
60 | ||
61 | /** | |
62 | * blkg_alloc - allocate a blkg | |
63 | * @blkcg: block cgroup the new blkg is associated with | |
64 | * @q: request_queue the new blkg is associated with | |
65 | * @gfp_mask: allocation mask to use | |
66 | * | |
67 | * Allocate a new blkg assocating @blkcg and @q. | |
68 | */ | |
69 | static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, | |
70 | gfp_t gfp_mask) | |
71 | { | |
72 | struct blkcg_gq *blkg; | |
73 | int i; | |
74 | ||
75 | /* alloc and init base part */ | |
76 | blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node); | |
77 | if (!blkg) | |
78 | return NULL; | |
79 | ||
80 | blkg->q = q; | |
81 | INIT_LIST_HEAD(&blkg->q_node); | |
82 | blkg->blkcg = blkcg; | |
83 | blkg->refcnt = 1; | |
84 | ||
85 | /* root blkg uses @q->root_rl, init rl only for !root blkgs */ | |
86 | if (blkcg != &blkcg_root) { | |
87 | if (blk_init_rl(&blkg->rl, q, gfp_mask)) | |
88 | goto err_free; | |
89 | blkg->rl.blkg = blkg; | |
90 | } | |
91 | ||
92 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
93 | struct blkcg_policy *pol = blkcg_policy[i]; | |
94 | struct blkg_policy_data *pd; | |
95 | ||
96 | if (!blkcg_policy_enabled(q, pol)) | |
97 | continue; | |
98 | ||
99 | /* alloc per-policy data and attach it to blkg */ | |
100 | pd = kzalloc_node(pol->pd_size, gfp_mask, q->node); | |
101 | if (!pd) | |
102 | goto err_free; | |
103 | ||
104 | blkg->pd[i] = pd; | |
105 | pd->blkg = blkg; | |
106 | pd->plid = i; | |
107 | } | |
108 | ||
109 | return blkg; | |
110 | ||
111 | err_free: | |
112 | blkg_free(blkg); | |
113 | return NULL; | |
114 | } | |
115 | ||
116 | /** | |
117 | * __blkg_lookup - internal version of blkg_lookup() | |
118 | * @blkcg: blkcg of interest | |
119 | * @q: request_queue of interest | |
120 | * @update_hint: whether to update lookup hint with the result or not | |
121 | * | |
122 | * This is internal version and shouldn't be used by policy | |
123 | * implementations. Looks up blkgs for the @blkcg - @q pair regardless of | |
124 | * @q's bypass state. If @update_hint is %true, the caller should be | |
125 | * holding @q->queue_lock and lookup hint is updated on success. | |
126 | */ | |
127 | struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q, | |
128 | bool update_hint) | |
129 | { | |
130 | struct blkcg_gq *blkg; | |
131 | ||
132 | blkg = rcu_dereference(blkcg->blkg_hint); | |
133 | if (blkg && blkg->q == q) | |
134 | return blkg; | |
135 | ||
136 | /* | |
137 | * Hint didn't match. Look up from the radix tree. Note that the | |
138 | * hint can only be updated under queue_lock as otherwise @blkg | |
139 | * could have already been removed from blkg_tree. The caller is | |
140 | * responsible for grabbing queue_lock if @update_hint. | |
141 | */ | |
142 | blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); | |
143 | if (blkg && blkg->q == q) { | |
144 | if (update_hint) { | |
145 | lockdep_assert_held(q->queue_lock); | |
146 | rcu_assign_pointer(blkcg->blkg_hint, blkg); | |
147 | } | |
148 | return blkg; | |
149 | } | |
150 | ||
151 | return NULL; | |
152 | } | |
153 | ||
154 | /** | |
155 | * blkg_lookup - lookup blkg for the specified blkcg - q pair | |
156 | * @blkcg: blkcg of interest | |
157 | * @q: request_queue of interest | |
158 | * | |
159 | * Lookup blkg for the @blkcg - @q pair. This function should be called | |
160 | * under RCU read lock and is guaranteed to return %NULL if @q is bypassing | |
161 | * - see blk_queue_bypass_start() for details. | |
162 | */ | |
163 | struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q) | |
164 | { | |
165 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
166 | ||
167 | if (unlikely(blk_queue_bypass(q))) | |
168 | return NULL; | |
169 | return __blkg_lookup(blkcg, q, false); | |
170 | } | |
171 | EXPORT_SYMBOL_GPL(blkg_lookup); | |
172 | ||
173 | /* | |
174 | * If @new_blkg is %NULL, this function tries to allocate a new one as | |
175 | * necessary using %GFP_ATOMIC. @new_blkg is always consumed on return. | |
176 | */ | |
177 | static struct blkcg_gq *blkg_create(struct blkcg *blkcg, | |
178 | struct request_queue *q, | |
179 | struct blkcg_gq *new_blkg) | |
180 | { | |
181 | struct blkcg_gq *blkg; | |
182 | int i, ret; | |
183 | ||
184 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
185 | lockdep_assert_held(q->queue_lock); | |
186 | ||
187 | /* blkg holds a reference to blkcg */ | |
188 | if (!css_tryget(&blkcg->css)) { | |
189 | ret = -EINVAL; | |
190 | goto err_free_blkg; | |
191 | } | |
192 | ||
193 | /* allocate */ | |
194 | if (!new_blkg) { | |
195 | new_blkg = blkg_alloc(blkcg, q, GFP_ATOMIC); | |
196 | if (unlikely(!new_blkg)) { | |
197 | ret = -ENOMEM; | |
198 | goto err_put_css; | |
199 | } | |
200 | } | |
201 | blkg = new_blkg; | |
202 | ||
203 | /* link parent */ | |
204 | if (blkcg_parent(blkcg)) { | |
205 | blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false); | |
206 | if (WARN_ON_ONCE(!blkg->parent)) { | |
207 | ret = -EINVAL; | |
208 | goto err_put_css; | |
209 | } | |
210 | blkg_get(blkg->parent); | |
211 | } | |
212 | ||
213 | /* invoke per-policy init */ | |
214 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
215 | struct blkcg_policy *pol = blkcg_policy[i]; | |
216 | ||
217 | if (blkg->pd[i] && pol->pd_init_fn) | |
218 | pol->pd_init_fn(blkg); | |
219 | } | |
220 | ||
221 | /* insert */ | |
222 | spin_lock(&blkcg->lock); | |
223 | ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg); | |
224 | if (likely(!ret)) { | |
225 | hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); | |
226 | list_add(&blkg->q_node, &q->blkg_list); | |
227 | ||
228 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
229 | struct blkcg_policy *pol = blkcg_policy[i]; | |
230 | ||
231 | if (blkg->pd[i] && pol->pd_online_fn) | |
232 | pol->pd_online_fn(blkg); | |
233 | } | |
234 | } | |
235 | blkg->online = true; | |
236 | spin_unlock(&blkcg->lock); | |
237 | ||
238 | if (!ret) | |
239 | return blkg; | |
240 | ||
241 | /* @blkg failed fully initialized, use the usual release path */ | |
242 | blkg_put(blkg); | |
243 | return ERR_PTR(ret); | |
244 | ||
245 | err_put_css: | |
246 | css_put(&blkcg->css); | |
247 | err_free_blkg: | |
248 | blkg_free(new_blkg); | |
249 | return ERR_PTR(ret); | |
250 | } | |
251 | ||
252 | /** | |
253 | * blkg_lookup_create - lookup blkg, try to create one if not there | |
254 | * @blkcg: blkcg of interest | |
255 | * @q: request_queue of interest | |
256 | * | |
257 | * Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to | |
258 | * create one. blkg creation is performed recursively from blkcg_root such | |
259 | * that all non-root blkg's have access to the parent blkg. This function | |
260 | * should be called under RCU read lock and @q->queue_lock. | |
261 | * | |
262 | * Returns pointer to the looked up or created blkg on success, ERR_PTR() | |
263 | * value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not | |
264 | * dead and bypassing, returns ERR_PTR(-EBUSY). | |
265 | */ | |
266 | struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, | |
267 | struct request_queue *q) | |
268 | { | |
269 | struct blkcg_gq *blkg; | |
270 | ||
271 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
272 | lockdep_assert_held(q->queue_lock); | |
273 | ||
274 | /* | |
275 | * This could be the first entry point of blkcg implementation and | |
276 | * we shouldn't allow anything to go through for a bypassing queue. | |
277 | */ | |
278 | if (unlikely(blk_queue_bypass(q))) | |
279 | return ERR_PTR(blk_queue_dying(q) ? -EINVAL : -EBUSY); | |
280 | ||
281 | blkg = __blkg_lookup(blkcg, q, true); | |
282 | if (blkg) | |
283 | return blkg; | |
284 | ||
285 | /* | |
286 | * Create blkgs walking down from blkcg_root to @blkcg, so that all | |
287 | * non-root blkgs have access to their parents. | |
288 | */ | |
289 | while (true) { | |
290 | struct blkcg *pos = blkcg; | |
291 | struct blkcg *parent = blkcg_parent(blkcg); | |
292 | ||
293 | while (parent && !__blkg_lookup(parent, q, false)) { | |
294 | pos = parent; | |
295 | parent = blkcg_parent(parent); | |
296 | } | |
297 | ||
298 | blkg = blkg_create(pos, q, NULL); | |
299 | if (pos == blkcg || IS_ERR(blkg)) | |
300 | return blkg; | |
301 | } | |
302 | } | |
303 | EXPORT_SYMBOL_GPL(blkg_lookup_create); | |
304 | ||
305 | static void blkg_destroy(struct blkcg_gq *blkg) | |
306 | { | |
307 | struct blkcg *blkcg = blkg->blkcg; | |
308 | int i; | |
309 | ||
310 | lockdep_assert_held(blkg->q->queue_lock); | |
311 | lockdep_assert_held(&blkcg->lock); | |
312 | ||
313 | /* Something wrong if we are trying to remove same group twice */ | |
314 | WARN_ON_ONCE(list_empty(&blkg->q_node)); | |
315 | WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node)); | |
316 | ||
317 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
318 | struct blkcg_policy *pol = blkcg_policy[i]; | |
319 | ||
320 | if (blkg->pd[i] && pol->pd_offline_fn) | |
321 | pol->pd_offline_fn(blkg); | |
322 | } | |
323 | blkg->online = false; | |
324 | ||
325 | radix_tree_delete(&blkcg->blkg_tree, blkg->q->id); | |
326 | list_del_init(&blkg->q_node); | |
327 | hlist_del_init_rcu(&blkg->blkcg_node); | |
328 | ||
329 | /* | |
330 | * Both setting lookup hint to and clearing it from @blkg are done | |
331 | * under queue_lock. If it's not pointing to @blkg now, it never | |
332 | * will. Hint assignment itself can race safely. | |
333 | */ | |
334 | if (rcu_dereference_raw(blkcg->blkg_hint) == blkg) | |
335 | rcu_assign_pointer(blkcg->blkg_hint, NULL); | |
336 | ||
337 | /* | |
338 | * Put the reference taken at the time of creation so that when all | |
339 | * queues are gone, group can be destroyed. | |
340 | */ | |
341 | blkg_put(blkg); | |
342 | } | |
343 | ||
344 | /** | |
345 | * blkg_destroy_all - destroy all blkgs associated with a request_queue | |
346 | * @q: request_queue of interest | |
347 | * | |
348 | * Destroy all blkgs associated with @q. | |
349 | */ | |
350 | static void blkg_destroy_all(struct request_queue *q) | |
351 | { | |
352 | struct blkcg_gq *blkg, *n; | |
353 | ||
354 | lockdep_assert_held(q->queue_lock); | |
355 | ||
356 | list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { | |
357 | struct blkcg *blkcg = blkg->blkcg; | |
358 | ||
359 | spin_lock(&blkcg->lock); | |
360 | blkg_destroy(blkg); | |
361 | spin_unlock(&blkcg->lock); | |
362 | } | |
363 | ||
364 | /* | |
365 | * root blkg is destroyed. Just clear the pointer since | |
366 | * root_rl does not take reference on root blkg. | |
367 | */ | |
368 | q->root_blkg = NULL; | |
369 | q->root_rl.blkg = NULL; | |
370 | } | |
371 | ||
372 | /* | |
373 | * A group is RCU protected, but having an rcu lock does not mean that one | |
374 | * can access all the fields of blkg and assume these are valid. For | |
375 | * example, don't try to follow throtl_data and request queue links. | |
376 | * | |
377 | * Having a reference to blkg under an rcu allows accesses to only values | |
378 | * local to groups like group stats and group rate limits. | |
379 | */ | |
380 | void __blkg_release_rcu(struct rcu_head *rcu_head) | |
381 | { | |
382 | struct blkcg_gq *blkg = container_of(rcu_head, struct blkcg_gq, rcu_head); | |
383 | int i; | |
384 | ||
385 | /* tell policies that this one is being freed */ | |
386 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
387 | struct blkcg_policy *pol = blkcg_policy[i]; | |
388 | ||
389 | if (blkg->pd[i] && pol->pd_exit_fn) | |
390 | pol->pd_exit_fn(blkg); | |
391 | } | |
392 | ||
393 | /* release the blkcg and parent blkg refs this blkg has been holding */ | |
394 | css_put(&blkg->blkcg->css); | |
395 | if (blkg->parent) { | |
396 | spin_lock_irq(blkg->q->queue_lock); | |
397 | blkg_put(blkg->parent); | |
398 | spin_unlock_irq(blkg->q->queue_lock); | |
399 | } | |
400 | ||
401 | blkg_free(blkg); | |
402 | } | |
403 | EXPORT_SYMBOL_GPL(__blkg_release_rcu); | |
404 | ||
405 | /* | |
406 | * The next function used by blk_queue_for_each_rl(). It's a bit tricky | |
407 | * because the root blkg uses @q->root_rl instead of its own rl. | |
408 | */ | |
409 | struct request_list *__blk_queue_next_rl(struct request_list *rl, | |
410 | struct request_queue *q) | |
411 | { | |
412 | struct list_head *ent; | |
413 | struct blkcg_gq *blkg; | |
414 | ||
415 | /* | |
416 | * Determine the current blkg list_head. The first entry is | |
417 | * root_rl which is off @q->blkg_list and mapped to the head. | |
418 | */ | |
419 | if (rl == &q->root_rl) { | |
420 | ent = &q->blkg_list; | |
421 | /* There are no more block groups, hence no request lists */ | |
422 | if (list_empty(ent)) | |
423 | return NULL; | |
424 | } else { | |
425 | blkg = container_of(rl, struct blkcg_gq, rl); | |
426 | ent = &blkg->q_node; | |
427 | } | |
428 | ||
429 | /* walk to the next list_head, skip root blkcg */ | |
430 | ent = ent->next; | |
431 | if (ent == &q->root_blkg->q_node) | |
432 | ent = ent->next; | |
433 | if (ent == &q->blkg_list) | |
434 | return NULL; | |
435 | ||
436 | blkg = container_of(ent, struct blkcg_gq, q_node); | |
437 | return &blkg->rl; | |
438 | } | |
439 | ||
440 | static int blkcg_reset_stats(struct cgroup_subsys_state *css, | |
441 | struct cftype *cftype, u64 val) | |
442 | { | |
443 | struct blkcg *blkcg = css_to_blkcg(css); | |
444 | struct blkcg_gq *blkg; | |
445 | int i; | |
446 | ||
447 | mutex_lock(&blkcg_pol_mutex); | |
448 | spin_lock_irq(&blkcg->lock); | |
449 | ||
450 | /* | |
451 | * Note that stat reset is racy - it doesn't synchronize against | |
452 | * stat updates. This is a debug feature which shouldn't exist | |
453 | * anyway. If you get hit by a race, retry. | |
454 | */ | |
455 | hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { | |
456 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
457 | struct blkcg_policy *pol = blkcg_policy[i]; | |
458 | ||
459 | if (blkcg_policy_enabled(blkg->q, pol) && | |
460 | pol->pd_reset_stats_fn) | |
461 | pol->pd_reset_stats_fn(blkg); | |
462 | } | |
463 | } | |
464 | ||
465 | spin_unlock_irq(&blkcg->lock); | |
466 | mutex_unlock(&blkcg_pol_mutex); | |
467 | return 0; | |
468 | } | |
469 | ||
470 | static const char *blkg_dev_name(struct blkcg_gq *blkg) | |
471 | { | |
472 | /* some drivers (floppy) instantiate a queue w/o disk registered */ | |
473 | if (blkg->q->backing_dev_info.dev) | |
474 | return dev_name(blkg->q->backing_dev_info.dev); | |
475 | return NULL; | |
476 | } | |
477 | ||
478 | /** | |
479 | * blkcg_print_blkgs - helper for printing per-blkg data | |
480 | * @sf: seq_file to print to | |
481 | * @blkcg: blkcg of interest | |
482 | * @prfill: fill function to print out a blkg | |
483 | * @pol: policy in question | |
484 | * @data: data to be passed to @prfill | |
485 | * @show_total: to print out sum of prfill return values or not | |
486 | * | |
487 | * This function invokes @prfill on each blkg of @blkcg if pd for the | |
488 | * policy specified by @pol exists. @prfill is invoked with @sf, the | |
489 | * policy data and @data and the matching queue lock held. If @show_total | |
490 | * is %true, the sum of the return values from @prfill is printed with | |
491 | * "Total" label at the end. | |
492 | * | |
493 | * This is to be used to construct print functions for | |
494 | * cftype->read_seq_string method. | |
495 | */ | |
496 | void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg, | |
497 | u64 (*prfill)(struct seq_file *, | |
498 | struct blkg_policy_data *, int), | |
499 | const struct blkcg_policy *pol, int data, | |
500 | bool show_total) | |
501 | { | |
502 | struct blkcg_gq *blkg; | |
503 | u64 total = 0; | |
504 | ||
505 | rcu_read_lock(); | |
506 | hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { | |
507 | spin_lock_irq(blkg->q->queue_lock); | |
508 | if (blkcg_policy_enabled(blkg->q, pol)) | |
509 | total += prfill(sf, blkg->pd[pol->plid], data); | |
510 | spin_unlock_irq(blkg->q->queue_lock); | |
511 | } | |
512 | rcu_read_unlock(); | |
513 | ||
514 | if (show_total) | |
515 | seq_printf(sf, "Total %llu\n", (unsigned long long)total); | |
516 | } | |
517 | EXPORT_SYMBOL_GPL(blkcg_print_blkgs); | |
518 | ||
519 | /** | |
520 | * __blkg_prfill_u64 - prfill helper for a single u64 value | |
521 | * @sf: seq_file to print to | |
522 | * @pd: policy private data of interest | |
523 | * @v: value to print | |
524 | * | |
525 | * Print @v to @sf for the device assocaited with @pd. | |
526 | */ | |
527 | u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v) | |
528 | { | |
529 | const char *dname = blkg_dev_name(pd->blkg); | |
530 | ||
531 | if (!dname) | |
532 | return 0; | |
533 | ||
534 | seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v); | |
535 | return v; | |
536 | } | |
537 | EXPORT_SYMBOL_GPL(__blkg_prfill_u64); | |
538 | ||
539 | /** | |
540 | * __blkg_prfill_rwstat - prfill helper for a blkg_rwstat | |
541 | * @sf: seq_file to print to | |
542 | * @pd: policy private data of interest | |
543 | * @rwstat: rwstat to print | |
544 | * | |
545 | * Print @rwstat to @sf for the device assocaited with @pd. | |
546 | */ | |
547 | u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, | |
548 | const struct blkg_rwstat *rwstat) | |
549 | { | |
550 | static const char *rwstr[] = { | |
551 | [BLKG_RWSTAT_READ] = "Read", | |
552 | [BLKG_RWSTAT_WRITE] = "Write", | |
553 | [BLKG_RWSTAT_SYNC] = "Sync", | |
554 | [BLKG_RWSTAT_ASYNC] = "Async", | |
555 | }; | |
556 | const char *dname = blkg_dev_name(pd->blkg); | |
557 | u64 v; | |
558 | int i; | |
559 | ||
560 | if (!dname) | |
561 | return 0; | |
562 | ||
563 | for (i = 0; i < BLKG_RWSTAT_NR; i++) | |
564 | seq_printf(sf, "%s %s %llu\n", dname, rwstr[i], | |
565 | (unsigned long long)rwstat->cnt[i]); | |
566 | ||
567 | v = rwstat->cnt[BLKG_RWSTAT_READ] + rwstat->cnt[BLKG_RWSTAT_WRITE]; | |
568 | seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v); | |
569 | return v; | |
570 | } | |
571 | EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat); | |
572 | ||
573 | /** | |
574 | * blkg_prfill_stat - prfill callback for blkg_stat | |
575 | * @sf: seq_file to print to | |
576 | * @pd: policy private data of interest | |
577 | * @off: offset to the blkg_stat in @pd | |
578 | * | |
579 | * prfill callback for printing a blkg_stat. | |
580 | */ | |
581 | u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off) | |
582 | { | |
583 | return __blkg_prfill_u64(sf, pd, blkg_stat_read((void *)pd + off)); | |
584 | } | |
585 | EXPORT_SYMBOL_GPL(blkg_prfill_stat); | |
586 | ||
587 | /** | |
588 | * blkg_prfill_rwstat - prfill callback for blkg_rwstat | |
589 | * @sf: seq_file to print to | |
590 | * @pd: policy private data of interest | |
591 | * @off: offset to the blkg_rwstat in @pd | |
592 | * | |
593 | * prfill callback for printing a blkg_rwstat. | |
594 | */ | |
595 | u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, | |
596 | int off) | |
597 | { | |
598 | struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd + off); | |
599 | ||
600 | return __blkg_prfill_rwstat(sf, pd, &rwstat); | |
601 | } | |
602 | EXPORT_SYMBOL_GPL(blkg_prfill_rwstat); | |
603 | ||
604 | /** | |
605 | * blkg_stat_recursive_sum - collect hierarchical blkg_stat | |
606 | * @pd: policy private data of interest | |
607 | * @off: offset to the blkg_stat in @pd | |
608 | * | |
609 | * Collect the blkg_stat specified by @off from @pd and all its online | |
610 | * descendants and return the sum. The caller must be holding the queue | |
611 | * lock for online tests. | |
612 | */ | |
613 | u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off) | |
614 | { | |
615 | struct blkcg_policy *pol = blkcg_policy[pd->plid]; | |
616 | struct blkcg_gq *pos_blkg; | |
617 | struct cgroup *pos_cgrp; | |
618 | u64 sum; | |
619 | ||
620 | lockdep_assert_held(pd->blkg->q->queue_lock); | |
621 | ||
622 | sum = blkg_stat_read((void *)pd + off); | |
623 | ||
624 | rcu_read_lock(); | |
625 | blkg_for_each_descendant_pre(pos_blkg, pos_cgrp, pd_to_blkg(pd)) { | |
626 | struct blkg_policy_data *pos_pd = blkg_to_pd(pos_blkg, pol); | |
627 | struct blkg_stat *stat = (void *)pos_pd + off; | |
628 | ||
629 | if (pos_blkg->online) | |
630 | sum += blkg_stat_read(stat); | |
631 | } | |
632 | rcu_read_unlock(); | |
633 | ||
634 | return sum; | |
635 | } | |
636 | EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum); | |
637 | ||
638 | /** | |
639 | * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat | |
640 | * @pd: policy private data of interest | |
641 | * @off: offset to the blkg_stat in @pd | |
642 | * | |
643 | * Collect the blkg_rwstat specified by @off from @pd and all its online | |
644 | * descendants and return the sum. The caller must be holding the queue | |
645 | * lock for online tests. | |
646 | */ | |
647 | struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd, | |
648 | int off) | |
649 | { | |
650 | struct blkcg_policy *pol = blkcg_policy[pd->plid]; | |
651 | struct blkcg_gq *pos_blkg; | |
652 | struct cgroup *pos_cgrp; | |
653 | struct blkg_rwstat sum; | |
654 | int i; | |
655 | ||
656 | lockdep_assert_held(pd->blkg->q->queue_lock); | |
657 | ||
658 | sum = blkg_rwstat_read((void *)pd + off); | |
659 | ||
660 | rcu_read_lock(); | |
661 | blkg_for_each_descendant_pre(pos_blkg, pos_cgrp, pd_to_blkg(pd)) { | |
662 | struct blkg_policy_data *pos_pd = blkg_to_pd(pos_blkg, pol); | |
663 | struct blkg_rwstat *rwstat = (void *)pos_pd + off; | |
664 | struct blkg_rwstat tmp; | |
665 | ||
666 | if (!pos_blkg->online) | |
667 | continue; | |
668 | ||
669 | tmp = blkg_rwstat_read(rwstat); | |
670 | ||
671 | for (i = 0; i < BLKG_RWSTAT_NR; i++) | |
672 | sum.cnt[i] += tmp.cnt[i]; | |
673 | } | |
674 | rcu_read_unlock(); | |
675 | ||
676 | return sum; | |
677 | } | |
678 | EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum); | |
679 | ||
680 | /** | |
681 | * blkg_conf_prep - parse and prepare for per-blkg config update | |
682 | * @blkcg: target block cgroup | |
683 | * @pol: target policy | |
684 | * @input: input string | |
685 | * @ctx: blkg_conf_ctx to be filled | |
686 | * | |
687 | * Parse per-blkg config update from @input and initialize @ctx with the | |
688 | * result. @ctx->blkg points to the blkg to be updated and @ctx->v the new | |
689 | * value. This function returns with RCU read lock and queue lock held and | |
690 | * must be paired with blkg_conf_finish(). | |
691 | */ | |
692 | int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, | |
693 | const char *input, struct blkg_conf_ctx *ctx) | |
694 | __acquires(rcu) __acquires(disk->queue->queue_lock) | |
695 | { | |
696 | struct gendisk *disk; | |
697 | struct blkcg_gq *blkg; | |
698 | unsigned int major, minor; | |
699 | unsigned long long v; | |
700 | int part, ret; | |
701 | ||
702 | if (sscanf(input, "%u:%u %llu", &major, &minor, &v) != 3) | |
703 | return -EINVAL; | |
704 | ||
705 | disk = get_gendisk(MKDEV(major, minor), &part); | |
706 | if (!disk || part) | |
707 | return -EINVAL; | |
708 | ||
709 | rcu_read_lock(); | |
710 | spin_lock_irq(disk->queue->queue_lock); | |
711 | ||
712 | if (blkcg_policy_enabled(disk->queue, pol)) | |
713 | blkg = blkg_lookup_create(blkcg, disk->queue); | |
714 | else | |
715 | blkg = ERR_PTR(-EINVAL); | |
716 | ||
717 | if (IS_ERR(blkg)) { | |
718 | ret = PTR_ERR(blkg); | |
719 | rcu_read_unlock(); | |
720 | spin_unlock_irq(disk->queue->queue_lock); | |
721 | put_disk(disk); | |
722 | /* | |
723 | * If queue was bypassing, we should retry. Do so after a | |
724 | * short msleep(). It isn't strictly necessary but queue | |
725 | * can be bypassing for some time and it's always nice to | |
726 | * avoid busy looping. | |
727 | */ | |
728 | if (ret == -EBUSY) { | |
729 | msleep(10); | |
730 | ret = restart_syscall(); | |
731 | } | |
732 | return ret; | |
733 | } | |
734 | ||
735 | ctx->disk = disk; | |
736 | ctx->blkg = blkg; | |
737 | ctx->v = v; | |
738 | return 0; | |
739 | } | |
740 | EXPORT_SYMBOL_GPL(blkg_conf_prep); | |
741 | ||
742 | /** | |
743 | * blkg_conf_finish - finish up per-blkg config update | |
744 | * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep() | |
745 | * | |
746 | * Finish up after per-blkg config update. This function must be paired | |
747 | * with blkg_conf_prep(). | |
748 | */ | |
749 | void blkg_conf_finish(struct blkg_conf_ctx *ctx) | |
750 | __releases(ctx->disk->queue->queue_lock) __releases(rcu) | |
751 | { | |
752 | spin_unlock_irq(ctx->disk->queue->queue_lock); | |
753 | rcu_read_unlock(); | |
754 | put_disk(ctx->disk); | |
755 | } | |
756 | EXPORT_SYMBOL_GPL(blkg_conf_finish); | |
757 | ||
758 | struct cftype blkcg_files[] = { | |
759 | { | |
760 | .name = "reset_stats", | |
761 | .write_u64 = blkcg_reset_stats, | |
762 | }, | |
763 | { } /* terminate */ | |
764 | }; | |
765 | ||
766 | /** | |
767 | * blkcg_css_offline - cgroup css_offline callback | |
768 | * @css: css of interest | |
769 | * | |
770 | * This function is called when @css is about to go away and responsible | |
771 | * for shooting down all blkgs associated with @css. blkgs should be | |
772 | * removed while holding both q and blkcg locks. As blkcg lock is nested | |
773 | * inside q lock, this function performs reverse double lock dancing. | |
774 | * | |
775 | * This is the blkcg counterpart of ioc_release_fn(). | |
776 | */ | |
777 | static void blkcg_css_offline(struct cgroup_subsys_state *css) | |
778 | { | |
779 | struct blkcg *blkcg = css_to_blkcg(css); | |
780 | ||
781 | spin_lock_irq(&blkcg->lock); | |
782 | ||
783 | while (!hlist_empty(&blkcg->blkg_list)) { | |
784 | struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first, | |
785 | struct blkcg_gq, blkcg_node); | |
786 | struct request_queue *q = blkg->q; | |
787 | ||
788 | if (spin_trylock(q->queue_lock)) { | |
789 | blkg_destroy(blkg); | |
790 | spin_unlock(q->queue_lock); | |
791 | } else { | |
792 | spin_unlock_irq(&blkcg->lock); | |
793 | cpu_relax(); | |
794 | spin_lock_irq(&blkcg->lock); | |
795 | } | |
796 | } | |
797 | ||
798 | spin_unlock_irq(&blkcg->lock); | |
799 | } | |
800 | ||
801 | static void blkcg_css_free(struct cgroup_subsys_state *css) | |
802 | { | |
803 | struct blkcg *blkcg = css_to_blkcg(css); | |
804 | ||
805 | if (blkcg != &blkcg_root) | |
806 | kfree(blkcg); | |
807 | } | |
808 | ||
809 | static struct cgroup_subsys_state * | |
810 | blkcg_css_alloc(struct cgroup_subsys_state *parent_css) | |
811 | { | |
812 | static atomic64_t id_seq = ATOMIC64_INIT(0); | |
813 | struct blkcg *blkcg; | |
814 | ||
815 | if (!parent_css) { | |
816 | blkcg = &blkcg_root; | |
817 | goto done; | |
818 | } | |
819 | ||
820 | blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); | |
821 | if (!blkcg) | |
822 | return ERR_PTR(-ENOMEM); | |
823 | ||
824 | blkcg->cfq_weight = CFQ_WEIGHT_DEFAULT; | |
825 | blkcg->cfq_leaf_weight = CFQ_WEIGHT_DEFAULT; | |
826 | blkcg->id = atomic64_inc_return(&id_seq); /* root is 0, start from 1 */ | |
827 | done: | |
828 | spin_lock_init(&blkcg->lock); | |
829 | INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_ATOMIC); | |
830 | INIT_HLIST_HEAD(&blkcg->blkg_list); | |
831 | ||
832 | return &blkcg->css; | |
833 | } | |
834 | ||
835 | /** | |
836 | * blkcg_init_queue - initialize blkcg part of request queue | |
837 | * @q: request_queue to initialize | |
838 | * | |
839 | * Called from blk_alloc_queue_node(). Responsible for initializing blkcg | |
840 | * part of new request_queue @q. | |
841 | * | |
842 | * RETURNS: | |
843 | * 0 on success, -errno on failure. | |
844 | */ | |
845 | int blkcg_init_queue(struct request_queue *q) | |
846 | { | |
847 | might_sleep(); | |
848 | ||
849 | return blk_throtl_init(q); | |
850 | } | |
851 | ||
852 | /** | |
853 | * blkcg_drain_queue - drain blkcg part of request_queue | |
854 | * @q: request_queue to drain | |
855 | * | |
856 | * Called from blk_drain_queue(). Responsible for draining blkcg part. | |
857 | */ | |
858 | void blkcg_drain_queue(struct request_queue *q) | |
859 | { | |
860 | lockdep_assert_held(q->queue_lock); | |
861 | ||
862 | blk_throtl_drain(q); | |
863 | } | |
864 | ||
865 | /** | |
866 | * blkcg_exit_queue - exit and release blkcg part of request_queue | |
867 | * @q: request_queue being released | |
868 | * | |
869 | * Called from blk_release_queue(). Responsible for exiting blkcg part. | |
870 | */ | |
871 | void blkcg_exit_queue(struct request_queue *q) | |
872 | { | |
873 | spin_lock_irq(q->queue_lock); | |
874 | blkg_destroy_all(q); | |
875 | spin_unlock_irq(q->queue_lock); | |
876 | ||
877 | blk_throtl_exit(q); | |
878 | } | |
879 | ||
880 | /* | |
881 | * We cannot support shared io contexts, as we have no mean to support | |
882 | * two tasks with the same ioc in two different groups without major rework | |
883 | * of the main cic data structures. For now we allow a task to change | |
884 | * its cgroup only if it's the only owner of its ioc. | |
885 | */ | |
886 | static int blkcg_can_attach(struct cgroup_subsys_state *css, | |
887 | struct cgroup_taskset *tset) | |
888 | { | |
889 | struct task_struct *task; | |
890 | struct io_context *ioc; | |
891 | int ret = 0; | |
892 | ||
893 | /* task_lock() is needed to avoid races with exit_io_context() */ | |
894 | cgroup_taskset_for_each(task, css->cgroup, tset) { | |
895 | task_lock(task); | |
896 | ioc = task->io_context; | |
897 | if (ioc && atomic_read(&ioc->nr_tasks) > 1) | |
898 | ret = -EINVAL; | |
899 | task_unlock(task); | |
900 | if (ret) | |
901 | break; | |
902 | } | |
903 | return ret; | |
904 | } | |
905 | ||
906 | struct cgroup_subsys blkio_subsys = { | |
907 | .name = "blkio", | |
908 | .css_alloc = blkcg_css_alloc, | |
909 | .css_offline = blkcg_css_offline, | |
910 | .css_free = blkcg_css_free, | |
911 | .can_attach = blkcg_can_attach, | |
912 | .subsys_id = blkio_subsys_id, | |
913 | .base_cftypes = blkcg_files, | |
914 | .module = THIS_MODULE, | |
915 | }; | |
916 | EXPORT_SYMBOL_GPL(blkio_subsys); | |
917 | ||
918 | /** | |
919 | * blkcg_activate_policy - activate a blkcg policy on a request_queue | |
920 | * @q: request_queue of interest | |
921 | * @pol: blkcg policy to activate | |
922 | * | |
923 | * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through | |
924 | * bypass mode to populate its blkgs with policy_data for @pol. | |
925 | * | |
926 | * Activation happens with @q bypassed, so nobody would be accessing blkgs | |
927 | * from IO path. Update of each blkg is protected by both queue and blkcg | |
928 | * locks so that holding either lock and testing blkcg_policy_enabled() is | |
929 | * always enough for dereferencing policy data. | |
930 | * | |
931 | * The caller is responsible for synchronizing [de]activations and policy | |
932 | * [un]registerations. Returns 0 on success, -errno on failure. | |
933 | */ | |
934 | int blkcg_activate_policy(struct request_queue *q, | |
935 | const struct blkcg_policy *pol) | |
936 | { | |
937 | LIST_HEAD(pds); | |
938 | struct blkcg_gq *blkg, *new_blkg; | |
939 | struct blkg_policy_data *pd, *n; | |
940 | int cnt = 0, ret; | |
941 | bool preloaded; | |
942 | ||
943 | if (blkcg_policy_enabled(q, pol)) | |
944 | return 0; | |
945 | ||
946 | /* preallocations for root blkg */ | |
947 | new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL); | |
948 | if (!new_blkg) | |
949 | return -ENOMEM; | |
950 | ||
951 | blk_queue_bypass_start(q); | |
952 | ||
953 | preloaded = !radix_tree_preload(GFP_KERNEL); | |
954 | ||
955 | /* | |
956 | * Make sure the root blkg exists and count the existing blkgs. As | |
957 | * @q is bypassing at this point, blkg_lookup_create() can't be | |
958 | * used. Open code it. | |
959 | */ | |
960 | spin_lock_irq(q->queue_lock); | |
961 | ||
962 | rcu_read_lock(); | |
963 | blkg = __blkg_lookup(&blkcg_root, q, false); | |
964 | if (blkg) | |
965 | blkg_free(new_blkg); | |
966 | else | |
967 | blkg = blkg_create(&blkcg_root, q, new_blkg); | |
968 | rcu_read_unlock(); | |
969 | ||
970 | if (preloaded) | |
971 | radix_tree_preload_end(); | |
972 | ||
973 | if (IS_ERR(blkg)) { | |
974 | ret = PTR_ERR(blkg); | |
975 | goto out_unlock; | |
976 | } | |
977 | q->root_blkg = blkg; | |
978 | q->root_rl.blkg = blkg; | |
979 | ||
980 | list_for_each_entry(blkg, &q->blkg_list, q_node) | |
981 | cnt++; | |
982 | ||
983 | spin_unlock_irq(q->queue_lock); | |
984 | ||
985 | /* allocate policy_data for all existing blkgs */ | |
986 | while (cnt--) { | |
987 | pd = kzalloc_node(pol->pd_size, GFP_KERNEL, q->node); | |
988 | if (!pd) { | |
989 | ret = -ENOMEM; | |
990 | goto out_free; | |
991 | } | |
992 | list_add_tail(&pd->alloc_node, &pds); | |
993 | } | |
994 | ||
995 | /* | |
996 | * Install the allocated pds. With @q bypassing, no new blkg | |
997 | * should have been created while the queue lock was dropped. | |
998 | */ | |
999 | spin_lock_irq(q->queue_lock); | |
1000 | ||
1001 | list_for_each_entry(blkg, &q->blkg_list, q_node) { | |
1002 | if (WARN_ON(list_empty(&pds))) { | |
1003 | /* umm... this shouldn't happen, just abort */ | |
1004 | ret = -ENOMEM; | |
1005 | goto out_unlock; | |
1006 | } | |
1007 | pd = list_first_entry(&pds, struct blkg_policy_data, alloc_node); | |
1008 | list_del_init(&pd->alloc_node); | |
1009 | ||
1010 | /* grab blkcg lock too while installing @pd on @blkg */ | |
1011 | spin_lock(&blkg->blkcg->lock); | |
1012 | ||
1013 | blkg->pd[pol->plid] = pd; | |
1014 | pd->blkg = blkg; | |
1015 | pd->plid = pol->plid; | |
1016 | pol->pd_init_fn(blkg); | |
1017 | ||
1018 | spin_unlock(&blkg->blkcg->lock); | |
1019 | } | |
1020 | ||
1021 | __set_bit(pol->plid, q->blkcg_pols); | |
1022 | ret = 0; | |
1023 | out_unlock: | |
1024 | spin_unlock_irq(q->queue_lock); | |
1025 | out_free: | |
1026 | blk_queue_bypass_end(q); | |
1027 | list_for_each_entry_safe(pd, n, &pds, alloc_node) | |
1028 | kfree(pd); | |
1029 | return ret; | |
1030 | } | |
1031 | EXPORT_SYMBOL_GPL(blkcg_activate_policy); | |
1032 | ||
1033 | /** | |
1034 | * blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue | |
1035 | * @q: request_queue of interest | |
1036 | * @pol: blkcg policy to deactivate | |
1037 | * | |
1038 | * Deactivate @pol on @q. Follows the same synchronization rules as | |
1039 | * blkcg_activate_policy(). | |
1040 | */ | |
1041 | void blkcg_deactivate_policy(struct request_queue *q, | |
1042 | const struct blkcg_policy *pol) | |
1043 | { | |
1044 | struct blkcg_gq *blkg; | |
1045 | ||
1046 | if (!blkcg_policy_enabled(q, pol)) | |
1047 | return; | |
1048 | ||
1049 | blk_queue_bypass_start(q); | |
1050 | spin_lock_irq(q->queue_lock); | |
1051 | ||
1052 | __clear_bit(pol->plid, q->blkcg_pols); | |
1053 | ||
1054 | /* if no policy is left, no need for blkgs - shoot them down */ | |
1055 | if (bitmap_empty(q->blkcg_pols, BLKCG_MAX_POLS)) | |
1056 | blkg_destroy_all(q); | |
1057 | ||
1058 | list_for_each_entry(blkg, &q->blkg_list, q_node) { | |
1059 | /* grab blkcg lock too while removing @pd from @blkg */ | |
1060 | spin_lock(&blkg->blkcg->lock); | |
1061 | ||
1062 | if (pol->pd_offline_fn) | |
1063 | pol->pd_offline_fn(blkg); | |
1064 | if (pol->pd_exit_fn) | |
1065 | pol->pd_exit_fn(blkg); | |
1066 | ||
1067 | kfree(blkg->pd[pol->plid]); | |
1068 | blkg->pd[pol->plid] = NULL; | |
1069 | ||
1070 | spin_unlock(&blkg->blkcg->lock); | |
1071 | } | |
1072 | ||
1073 | spin_unlock_irq(q->queue_lock); | |
1074 | blk_queue_bypass_end(q); | |
1075 | } | |
1076 | EXPORT_SYMBOL_GPL(blkcg_deactivate_policy); | |
1077 | ||
1078 | /** | |
1079 | * blkcg_policy_register - register a blkcg policy | |
1080 | * @pol: blkcg policy to register | |
1081 | * | |
1082 | * Register @pol with blkcg core. Might sleep and @pol may be modified on | |
1083 | * successful registration. Returns 0 on success and -errno on failure. | |
1084 | */ | |
1085 | int blkcg_policy_register(struct blkcg_policy *pol) | |
1086 | { | |
1087 | int i, ret; | |
1088 | ||
1089 | if (WARN_ON(pol->pd_size < sizeof(struct blkg_policy_data))) | |
1090 | return -EINVAL; | |
1091 | ||
1092 | mutex_lock(&blkcg_pol_mutex); | |
1093 | ||
1094 | /* find an empty slot */ | |
1095 | ret = -ENOSPC; | |
1096 | for (i = 0; i < BLKCG_MAX_POLS; i++) | |
1097 | if (!blkcg_policy[i]) | |
1098 | break; | |
1099 | if (i >= BLKCG_MAX_POLS) | |
1100 | goto out_unlock; | |
1101 | ||
1102 | /* register and update blkgs */ | |
1103 | pol->plid = i; | |
1104 | blkcg_policy[i] = pol; | |
1105 | ||
1106 | /* everything is in place, add intf files for the new policy */ | |
1107 | if (pol->cftypes) | |
1108 | WARN_ON(cgroup_add_cftypes(&blkio_subsys, pol->cftypes)); | |
1109 | ret = 0; | |
1110 | out_unlock: | |
1111 | mutex_unlock(&blkcg_pol_mutex); | |
1112 | return ret; | |
1113 | } | |
1114 | EXPORT_SYMBOL_GPL(blkcg_policy_register); | |
1115 | ||
1116 | /** | |
1117 | * blkcg_policy_unregister - unregister a blkcg policy | |
1118 | * @pol: blkcg policy to unregister | |
1119 | * | |
1120 | * Undo blkcg_policy_register(@pol). Might sleep. | |
1121 | */ | |
1122 | void blkcg_policy_unregister(struct blkcg_policy *pol) | |
1123 | { | |
1124 | mutex_lock(&blkcg_pol_mutex); | |
1125 | ||
1126 | if (WARN_ON(blkcg_policy[pol->plid] != pol)) | |
1127 | goto out_unlock; | |
1128 | ||
1129 | /* kill the intf files first */ | |
1130 | if (pol->cftypes) | |
1131 | cgroup_rm_cftypes(pol->cftypes); | |
1132 | ||
1133 | /* unregister and update blkgs */ | |
1134 | blkcg_policy[pol->plid] = NULL; | |
1135 | out_unlock: | |
1136 | mutex_unlock(&blkcg_pol_mutex); | |
1137 | } | |
1138 | EXPORT_SYMBOL_GPL(blkcg_policy_unregister); |