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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 | * For policy-specific per-blkcg data: | |
14 | * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it> | |
15 | * Arianna Avanzini <avanzini.arianna@gmail.com> | |
16 | */ | |
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> | |
28 | #include "blk.h" | |
29 | ||
30 | #define MAX_KEY_LEN 100 | |
31 | ||
32 | /* | |
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. | |
38 | */ | |
39 | static DEFINE_MUTEX(blkcg_pol_register_mutex); | |
40 | static DEFINE_MUTEX(blkcg_pol_mutex); | |
41 | ||
42 | struct blkcg blkcg_root; | |
43 | EXPORT_SYMBOL_GPL(blkcg_root); | |
44 | ||
45 | struct cgroup_subsys_state * const blkcg_root_css = &blkcg_root.css; | |
46 | ||
47 | static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS]; | |
48 | ||
49 | static LIST_HEAD(all_blkcgs); /* protected by blkcg_pol_mutex */ | |
50 | ||
51 | static bool blkcg_policy_enabled(struct request_queue *q, | |
52 | const struct blkcg_policy *pol) | |
53 | { | |
54 | return pol && test_bit(pol->plid, q->blkcg_pols); | |
55 | } | |
56 | ||
57 | /** | |
58 | * blkg_free - free a blkg | |
59 | * @blkg: blkg to free | |
60 | * | |
61 | * Free @blkg which may be partially allocated. | |
62 | */ | |
63 | static void blkg_free(struct blkcg_gq *blkg) | |
64 | { | |
65 | int i; | |
66 | ||
67 | if (!blkg) | |
68 | return; | |
69 | ||
70 | for (i = 0; i < BLKCG_MAX_POLS; i++) | |
71 | kfree(blkg->pd[i]); | |
72 | ||
73 | blk_exit_rl(&blkg->rl); | |
74 | kfree(blkg); | |
75 | } | |
76 | ||
77 | /** | |
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 | |
82 | * | |
83 | * Allocate a new blkg assocating @blkcg and @q. | |
84 | */ | |
85 | static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, | |
86 | gfp_t gfp_mask) | |
87 | { | |
88 | struct blkcg_gq *blkg; | |
89 | int i; | |
90 | ||
91 | /* alloc and init base part */ | |
92 | blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node); | |
93 | if (!blkg) | |
94 | return NULL; | |
95 | ||
96 | blkg->q = q; | |
97 | INIT_LIST_HEAD(&blkg->q_node); | |
98 | blkg->blkcg = blkcg; | |
99 | atomic_set(&blkg->refcnt, 1); | |
100 | ||
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)) | |
104 | goto err_free; | |
105 | blkg->rl.blkg = blkg; | |
106 | } | |
107 | ||
108 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
109 | struct blkcg_policy *pol = blkcg_policy[i]; | |
110 | struct blkg_policy_data *pd; | |
111 | ||
112 | if (!blkcg_policy_enabled(q, pol)) | |
113 | continue; | |
114 | ||
115 | /* alloc per-policy data and attach it to blkg */ | |
116 | pd = kzalloc_node(pol->pd_size, gfp_mask, q->node); | |
117 | if (!pd) | |
118 | goto err_free; | |
119 | ||
120 | blkg->pd[i] = pd; | |
121 | pd->blkg = blkg; | |
122 | pd->plid = i; | |
123 | } | |
124 | ||
125 | return blkg; | |
126 | ||
127 | err_free: | |
128 | blkg_free(blkg); | |
129 | return NULL; | |
130 | } | |
131 | ||
132 | /** | |
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 | |
137 | * | |
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. | |
142 | */ | |
143 | struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q, | |
144 | bool update_hint) | |
145 | { | |
146 | struct blkcg_gq *blkg; | |
147 | ||
148 | blkg = rcu_dereference(blkcg->blkg_hint); | |
149 | if (blkg && blkg->q == q) | |
150 | return blkg; | |
151 | ||
152 | /* | |
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. | |
157 | */ | |
158 | blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); | |
159 | if (blkg && blkg->q == q) { | |
160 | if (update_hint) { | |
161 | lockdep_assert_held(q->queue_lock); | |
162 | rcu_assign_pointer(blkcg->blkg_hint, blkg); | |
163 | } | |
164 | return blkg; | |
165 | } | |
166 | ||
167 | return NULL; | |
168 | } | |
169 | ||
170 | /** | |
171 | * blkg_lookup - lookup blkg for the specified blkcg - q pair | |
172 | * @blkcg: blkcg of interest | |
173 | * @q: request_queue of interest | |
174 | * | |
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. | |
178 | */ | |
179 | struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q) | |
180 | { | |
181 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
182 | ||
183 | if (unlikely(blk_queue_bypass(q))) | |
184 | return NULL; | |
185 | return __blkg_lookup(blkcg, q, false); | |
186 | } | |
187 | EXPORT_SYMBOL_GPL(blkg_lookup); | |
188 | ||
189 | /* | |
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. | |
192 | */ | |
193 | static struct blkcg_gq *blkg_create(struct blkcg *blkcg, | |
194 | struct request_queue *q, | |
195 | struct blkcg_gq *new_blkg) | |
196 | { | |
197 | struct blkcg_gq *blkg; | |
198 | struct bdi_writeback_congested *wb_congested; | |
199 | int i, ret; | |
200 | ||
201 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
202 | lockdep_assert_held(q->queue_lock); | |
203 | ||
204 | /* blkg holds a reference to blkcg */ | |
205 | if (!css_tryget_online(&blkcg->css)) { | |
206 | ret = -EINVAL; | |
207 | goto err_free_blkg; | |
208 | } | |
209 | ||
210 | wb_congested = wb_congested_get_create(&q->backing_dev_info, | |
211 | blkcg->css.id, GFP_ATOMIC); | |
212 | if (!wb_congested) { | |
213 | ret = -ENOMEM; | |
214 | goto err_put_css; | |
215 | } | |
216 | ||
217 | /* allocate */ | |
218 | if (!new_blkg) { | |
219 | new_blkg = blkg_alloc(blkcg, q, GFP_ATOMIC); | |
220 | if (unlikely(!new_blkg)) { | |
221 | ret = -ENOMEM; | |
222 | goto err_put_congested; | |
223 | } | |
224 | } | |
225 | blkg = new_blkg; | |
226 | blkg->wb_congested = wb_congested; | |
227 | ||
228 | /* link parent */ | |
229 | if (blkcg_parent(blkcg)) { | |
230 | blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false); | |
231 | if (WARN_ON_ONCE(!blkg->parent)) { | |
232 | ret = -EINVAL; | |
233 | goto err_put_congested; | |
234 | } | |
235 | blkg_get(blkg->parent); | |
236 | } | |
237 | ||
238 | /* invoke per-policy init */ | |
239 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
240 | struct blkcg_policy *pol = blkcg_policy[i]; | |
241 | ||
242 | if (blkg->pd[i] && pol->pd_init_fn) | |
243 | pol->pd_init_fn(blkg); | |
244 | } | |
245 | ||
246 | /* insert */ | |
247 | spin_lock(&blkcg->lock); | |
248 | ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg); | |
249 | if (likely(!ret)) { | |
250 | hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); | |
251 | list_add(&blkg->q_node, &q->blkg_list); | |
252 | ||
253 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
254 | struct blkcg_policy *pol = blkcg_policy[i]; | |
255 | ||
256 | if (blkg->pd[i] && pol->pd_online_fn) | |
257 | pol->pd_online_fn(blkg); | |
258 | } | |
259 | } | |
260 | blkg->online = true; | |
261 | spin_unlock(&blkcg->lock); | |
262 | ||
263 | if (!ret) | |
264 | return blkg; | |
265 | ||
266 | /* @blkg failed fully initialized, use the usual release path */ | |
267 | blkg_put(blkg); | |
268 | return ERR_PTR(ret); | |
269 | ||
270 | err_put_congested: | |
271 | wb_congested_put(wb_congested); | |
272 | err_put_css: | |
273 | css_put(&blkcg->css); | |
274 | err_free_blkg: | |
275 | blkg_free(new_blkg); | |
276 | return ERR_PTR(ret); | |
277 | } | |
278 | ||
279 | /** | |
280 | * blkg_lookup_create - lookup blkg, try to create one if not there | |
281 | * @blkcg: blkcg of interest | |
282 | * @q: request_queue of interest | |
283 | * | |
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. | |
288 | * | |
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). | |
292 | */ | |
293 | struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, | |
294 | struct request_queue *q) | |
295 | { | |
296 | struct blkcg_gq *blkg; | |
297 | ||
298 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
299 | lockdep_assert_held(q->queue_lock); | |
300 | ||
301 | /* | |
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. | |
304 | */ | |
305 | if (unlikely(blk_queue_bypass(q))) | |
306 | return ERR_PTR(blk_queue_dying(q) ? -EINVAL : -EBUSY); | |
307 | ||
308 | blkg = __blkg_lookup(blkcg, q, true); | |
309 | if (blkg) | |
310 | return blkg; | |
311 | ||
312 | /* | |
313 | * Create blkgs walking down from blkcg_root to @blkcg, so that all | |
314 | * non-root blkgs have access to their parents. | |
315 | */ | |
316 | while (true) { | |
317 | struct blkcg *pos = blkcg; | |
318 | struct blkcg *parent = blkcg_parent(blkcg); | |
319 | ||
320 | while (parent && !__blkg_lookup(parent, q, false)) { | |
321 | pos = parent; | |
322 | parent = blkcg_parent(parent); | |
323 | } | |
324 | ||
325 | blkg = blkg_create(pos, q, NULL); | |
326 | if (pos == blkcg || IS_ERR(blkg)) | |
327 | return blkg; | |
328 | } | |
329 | } | |
330 | EXPORT_SYMBOL_GPL(blkg_lookup_create); | |
331 | ||
332 | static void blkg_destroy(struct blkcg_gq *blkg) | |
333 | { | |
334 | struct blkcg *blkcg = blkg->blkcg; | |
335 | int i; | |
336 | ||
337 | lockdep_assert_held(blkg->q->queue_lock); | |
338 | lockdep_assert_held(&blkcg->lock); | |
339 | ||
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)); | |
343 | ||
344 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
345 | struct blkcg_policy *pol = blkcg_policy[i]; | |
346 | ||
347 | if (blkg->pd[i] && pol->pd_offline_fn) | |
348 | pol->pd_offline_fn(blkg); | |
349 | } | |
350 | blkg->online = false; | |
351 | ||
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); | |
355 | ||
356 | /* | |
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. | |
360 | */ | |
361 | if (rcu_access_pointer(blkcg->blkg_hint) == blkg) | |
362 | rcu_assign_pointer(blkcg->blkg_hint, NULL); | |
363 | ||
364 | /* | |
365 | * Put the reference taken at the time of creation so that when all | |
366 | * queues are gone, group can be destroyed. | |
367 | */ | |
368 | blkg_put(blkg); | |
369 | } | |
370 | ||
371 | /** | |
372 | * blkg_destroy_all - destroy all blkgs associated with a request_queue | |
373 | * @q: request_queue of interest | |
374 | * | |
375 | * Destroy all blkgs associated with @q. | |
376 | */ | |
377 | static void blkg_destroy_all(struct request_queue *q) | |
378 | { | |
379 | struct blkcg_gq *blkg, *n; | |
380 | ||
381 | lockdep_assert_held(q->queue_lock); | |
382 | ||
383 | list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { | |
384 | struct blkcg *blkcg = blkg->blkcg; | |
385 | ||
386 | spin_lock(&blkcg->lock); | |
387 | blkg_destroy(blkg); | |
388 | spin_unlock(&blkcg->lock); | |
389 | } | |
390 | } | |
391 | ||
392 | /* | |
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. | |
396 | * | |
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. | |
399 | */ | |
400 | void __blkg_release_rcu(struct rcu_head *rcu_head) | |
401 | { | |
402 | struct blkcg_gq *blkg = container_of(rcu_head, struct blkcg_gq, rcu_head); | |
403 | int i; | |
404 | ||
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]; | |
408 | ||
409 | if (blkg->pd[i] && pol->pd_exit_fn) | |
410 | pol->pd_exit_fn(blkg); | |
411 | } | |
412 | ||
413 | /* release the blkcg and parent blkg refs this blkg has been holding */ | |
414 | css_put(&blkg->blkcg->css); | |
415 | if (blkg->parent) | |
416 | blkg_put(blkg->parent); | |
417 | ||
418 | wb_congested_put(blkg->wb_congested); | |
419 | ||
420 | blkg_free(blkg); | |
421 | } | |
422 | EXPORT_SYMBOL_GPL(__blkg_release_rcu); | |
423 | ||
424 | /* | |
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. | |
427 | */ | |
428 | struct request_list *__blk_queue_next_rl(struct request_list *rl, | |
429 | struct request_queue *q) | |
430 | { | |
431 | struct list_head *ent; | |
432 | struct blkcg_gq *blkg; | |
433 | ||
434 | /* | |
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. | |
437 | */ | |
438 | if (rl == &q->root_rl) { | |
439 | ent = &q->blkg_list; | |
440 | /* There are no more block groups, hence no request lists */ | |
441 | if (list_empty(ent)) | |
442 | return NULL; | |
443 | } else { | |
444 | blkg = container_of(rl, struct blkcg_gq, rl); | |
445 | ent = &blkg->q_node; | |
446 | } | |
447 | ||
448 | /* walk to the next list_head, skip root blkcg */ | |
449 | ent = ent->next; | |
450 | if (ent == &q->root_blkg->q_node) | |
451 | ent = ent->next; | |
452 | if (ent == &q->blkg_list) | |
453 | return NULL; | |
454 | ||
455 | blkg = container_of(ent, struct blkcg_gq, q_node); | |
456 | return &blkg->rl; | |
457 | } | |
458 | ||
459 | static int blkcg_reset_stats(struct cgroup_subsys_state *css, | |
460 | struct cftype *cftype, u64 val) | |
461 | { | |
462 | struct blkcg *blkcg = css_to_blkcg(css); | |
463 | struct blkcg_gq *blkg; | |
464 | int i; | |
465 | ||
466 | mutex_lock(&blkcg_pol_mutex); | |
467 | spin_lock_irq(&blkcg->lock); | |
468 | ||
469 | /* | |
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. | |
473 | */ | |
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]; | |
477 | ||
478 | if (blkcg_policy_enabled(blkg->q, pol) && | |
479 | pol->pd_reset_stats_fn) | |
480 | pol->pd_reset_stats_fn(blkg); | |
481 | } | |
482 | } | |
483 | ||
484 | spin_unlock_irq(&blkcg->lock); | |
485 | mutex_unlock(&blkcg_pol_mutex); | |
486 | return 0; | |
487 | } | |
488 | ||
489 | static const char *blkg_dev_name(struct blkcg_gq *blkg) | |
490 | { | |
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); | |
494 | return NULL; | |
495 | } | |
496 | ||
497 | /** | |
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 | |
505 | * | |
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. | |
511 | * | |
512 | * This is to be used to construct print functions for | |
513 | * cftype->read_seq_string method. | |
514 | */ | |
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, | |
519 | bool show_total) | |
520 | { | |
521 | struct blkcg_gq *blkg; | |
522 | u64 total = 0; | |
523 | ||
524 | rcu_read_lock(); | |
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); | |
530 | } | |
531 | rcu_read_unlock(); | |
532 | ||
533 | if (show_total) | |
534 | seq_printf(sf, "Total %llu\n", (unsigned long long)total); | |
535 | } | |
536 | EXPORT_SYMBOL_GPL(blkcg_print_blkgs); | |
537 | ||
538 | /** | |
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 | |
542 | * @v: value to print | |
543 | * | |
544 | * Print @v to @sf for the device assocaited with @pd. | |
545 | */ | |
546 | u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v) | |
547 | { | |
548 | const char *dname = blkg_dev_name(pd->blkg); | |
549 | ||
550 | if (!dname) | |
551 | return 0; | |
552 | ||
553 | seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v); | |
554 | return v; | |
555 | } | |
556 | EXPORT_SYMBOL_GPL(__blkg_prfill_u64); | |
557 | ||
558 | /** | |
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 | |
563 | * | |
564 | * Print @rwstat to @sf for the device assocaited with @pd. | |
565 | */ | |
566 | u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, | |
567 | const struct blkg_rwstat *rwstat) | |
568 | { | |
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", | |
574 | }; | |
575 | const char *dname = blkg_dev_name(pd->blkg); | |
576 | u64 v; | |
577 | int i; | |
578 | ||
579 | if (!dname) | |
580 | return 0; | |
581 | ||
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]); | |
585 | ||
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); | |
588 | return v; | |
589 | } | |
590 | EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat); | |
591 | ||
592 | /** | |
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 | |
597 | * | |
598 | * prfill callback for printing a blkg_stat. | |
599 | */ | |
600 | u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off) | |
601 | { | |
602 | return __blkg_prfill_u64(sf, pd, blkg_stat_read((void *)pd + off)); | |
603 | } | |
604 | EXPORT_SYMBOL_GPL(blkg_prfill_stat); | |
605 | ||
606 | /** | |
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 | |
611 | * | |
612 | * prfill callback for printing a blkg_rwstat. | |
613 | */ | |
614 | u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, | |
615 | int off) | |
616 | { | |
617 | struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd + off); | |
618 | ||
619 | return __blkg_prfill_rwstat(sf, pd, &rwstat); | |
620 | } | |
621 | EXPORT_SYMBOL_GPL(blkg_prfill_rwstat); | |
622 | ||
623 | /** | |
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 | |
627 | * | |
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. | |
631 | */ | |
632 | u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off) | |
633 | { | |
634 | struct blkcg_policy *pol = blkcg_policy[pd->plid]; | |
635 | struct blkcg_gq *pos_blkg; | |
636 | struct cgroup_subsys_state *pos_css; | |
637 | u64 sum = 0; | |
638 | ||
639 | lockdep_assert_held(pd->blkg->q->queue_lock); | |
640 | ||
641 | rcu_read_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; | |
645 | ||
646 | if (pos_blkg->online) | |
647 | sum += blkg_stat_read(stat); | |
648 | } | |
649 | rcu_read_unlock(); | |
650 | ||
651 | return sum; | |
652 | } | |
653 | EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum); | |
654 | ||
655 | /** | |
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 | |
659 | * | |
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. | |
663 | */ | |
664 | struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd, | |
665 | int off) | |
666 | { | |
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 = { }; | |
671 | int i; | |
672 | ||
673 | lockdep_assert_held(pd->blkg->q->queue_lock); | |
674 | ||
675 | rcu_read_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; | |
680 | ||
681 | if (!pos_blkg->online) | |
682 | continue; | |
683 | ||
684 | tmp = blkg_rwstat_read(rwstat); | |
685 | ||
686 | for (i = 0; i < BLKG_RWSTAT_NR; i++) | |
687 | sum.cnt[i] += tmp.cnt[i]; | |
688 | } | |
689 | rcu_read_unlock(); | |
690 | ||
691 | return sum; | |
692 | } | |
693 | EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum); | |
694 | ||
695 | /** | |
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 | |
701 | * | |
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(). | |
706 | */ | |
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) | |
710 | { | |
711 | struct gendisk *disk; | |
712 | struct blkcg_gq *blkg; | |
713 | unsigned int major, minor; | |
714 | unsigned long long v; | |
715 | int part, ret; | |
716 | ||
717 | if (sscanf(input, "%u:%u %llu", &major, &minor, &v) != 3) | |
718 | return -EINVAL; | |
719 | ||
720 | disk = get_gendisk(MKDEV(major, minor), &part); | |
721 | if (!disk || part) | |
722 | return -EINVAL; | |
723 | ||
724 | rcu_read_lock(); | |
725 | spin_lock_irq(disk->queue->queue_lock); | |
726 | ||
727 | if (blkcg_policy_enabled(disk->queue, pol)) | |
728 | blkg = blkg_lookup_create(blkcg, disk->queue); | |
729 | else | |
730 | blkg = ERR_PTR(-EINVAL); | |
731 | ||
732 | if (IS_ERR(blkg)) { | |
733 | ret = PTR_ERR(blkg); | |
734 | rcu_read_unlock(); | |
735 | spin_unlock_irq(disk->queue->queue_lock); | |
736 | put_disk(disk); | |
737 | /* | |
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. | |
742 | */ | |
743 | if (ret == -EBUSY) { | |
744 | msleep(10); | |
745 | ret = restart_syscall(); | |
746 | } | |
747 | return ret; | |
748 | } | |
749 | ||
750 | ctx->disk = disk; | |
751 | ctx->blkg = blkg; | |
752 | ctx->v = v; | |
753 | return 0; | |
754 | } | |
755 | EXPORT_SYMBOL_GPL(blkg_conf_prep); | |
756 | ||
757 | /** | |
758 | * blkg_conf_finish - finish up per-blkg config update | |
759 | * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep() | |
760 | * | |
761 | * Finish up after per-blkg config update. This function must be paired | |
762 | * with blkg_conf_prep(). | |
763 | */ | |
764 | void blkg_conf_finish(struct blkg_conf_ctx *ctx) | |
765 | __releases(ctx->disk->queue->queue_lock) __releases(rcu) | |
766 | { | |
767 | spin_unlock_irq(ctx->disk->queue->queue_lock); | |
768 | rcu_read_unlock(); | |
769 | put_disk(ctx->disk); | |
770 | } | |
771 | EXPORT_SYMBOL_GPL(blkg_conf_finish); | |
772 | ||
773 | struct cftype blkcg_files[] = { | |
774 | { | |
775 | .name = "reset_stats", | |
776 | .write_u64 = blkcg_reset_stats, | |
777 | }, | |
778 | { } /* terminate */ | |
779 | }; | |
780 | ||
781 | /** | |
782 | * blkcg_css_offline - cgroup css_offline callback | |
783 | * @css: css of interest | |
784 | * | |
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. | |
789 | * | |
790 | * This is the blkcg counterpart of ioc_release_fn(). | |
791 | */ | |
792 | static void blkcg_css_offline(struct cgroup_subsys_state *css) | |
793 | { | |
794 | struct blkcg *blkcg = css_to_blkcg(css); | |
795 | ||
796 | spin_lock_irq(&blkcg->lock); | |
797 | ||
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; | |
802 | ||
803 | if (spin_trylock(q->queue_lock)) { | |
804 | blkg_destroy(blkg); | |
805 | spin_unlock(q->queue_lock); | |
806 | } else { | |
807 | spin_unlock_irq(&blkcg->lock); | |
808 | cpu_relax(); | |
809 | spin_lock_irq(&blkcg->lock); | |
810 | } | |
811 | } | |
812 | ||
813 | spin_unlock_irq(&blkcg->lock); | |
814 | ||
815 | wb_blkcg_offline(blkcg); | |
816 | } | |
817 | ||
818 | static void blkcg_css_free(struct cgroup_subsys_state *css) | |
819 | { | |
820 | struct blkcg *blkcg = css_to_blkcg(css); | |
821 | ||
822 | mutex_lock(&blkcg_pol_mutex); | |
823 | list_del(&blkcg->all_blkcgs_node); | |
824 | mutex_unlock(&blkcg_pol_mutex); | |
825 | ||
826 | if (blkcg != &blkcg_root) { | |
827 | int i; | |
828 | ||
829 | for (i = 0; i < BLKCG_MAX_POLS; i++) | |
830 | kfree(blkcg->pd[i]); | |
831 | kfree(blkcg); | |
832 | } | |
833 | } | |
834 | ||
835 | static struct cgroup_subsys_state * | |
836 | blkcg_css_alloc(struct cgroup_subsys_state *parent_css) | |
837 | { | |
838 | struct blkcg *blkcg; | |
839 | struct cgroup_subsys_state *ret; | |
840 | int i; | |
841 | ||
842 | mutex_lock(&blkcg_pol_mutex); | |
843 | ||
844 | if (!parent_css) { | |
845 | blkcg = &blkcg_root; | |
846 | goto done; | |
847 | } | |
848 | ||
849 | blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); | |
850 | if (!blkcg) { | |
851 | ret = ERR_PTR(-ENOMEM); | |
852 | goto free_blkcg; | |
853 | } | |
854 | ||
855 | for (i = 0; i < BLKCG_MAX_POLS ; i++) { | |
856 | struct blkcg_policy *pol = blkcg_policy[i]; | |
857 | struct blkcg_policy_data *cpd; | |
858 | ||
859 | /* | |
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. | |
864 | */ | |
865 | if (!pol || !pol->cpd_size) | |
866 | continue; | |
867 | ||
868 | BUG_ON(blkcg->pd[i]); | |
869 | cpd = kzalloc(pol->cpd_size, GFP_KERNEL); | |
870 | if (!cpd) { | |
871 | ret = ERR_PTR(-ENOMEM); | |
872 | goto free_pd_blkcg; | |
873 | } | |
874 | blkcg->pd[i] = cpd; | |
875 | cpd->plid = i; | |
876 | pol->cpd_init_fn(blkcg); | |
877 | } | |
878 | ||
879 | done: | |
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); | |
885 | #endif | |
886 | list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs); | |
887 | ||
888 | mutex_unlock(&blkcg_pol_mutex); | |
889 | return &blkcg->css; | |
890 | ||
891 | free_pd_blkcg: | |
892 | for (i--; i >= 0; i--) | |
893 | kfree(blkcg->pd[i]); | |
894 | free_blkcg: | |
895 | kfree(blkcg); | |
896 | mutex_unlock(&blkcg_pol_mutex); | |
897 | return ret; | |
898 | } | |
899 | ||
900 | /** | |
901 | * blkcg_init_queue - initialize blkcg part of request queue | |
902 | * @q: request_queue to initialize | |
903 | * | |
904 | * Called from blk_alloc_queue_node(). Responsible for initializing blkcg | |
905 | * part of new request_queue @q. | |
906 | * | |
907 | * RETURNS: | |
908 | * 0 on success, -errno on failure. | |
909 | */ | |
910 | int blkcg_init_queue(struct request_queue *q) | |
911 | { | |
912 | struct blkcg_gq *new_blkg, *blkg; | |
913 | bool preloaded; | |
914 | int ret; | |
915 | ||
916 | new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL); | |
917 | if (!new_blkg) | |
918 | return -ENOMEM; | |
919 | ||
920 | preloaded = !radix_tree_preload(GFP_KERNEL); | |
921 | ||
922 | /* | |
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. | |
926 | */ | |
927 | rcu_read_lock(); | |
928 | spin_lock_irq(q->queue_lock); | |
929 | blkg = blkg_create(&blkcg_root, q, new_blkg); | |
930 | spin_unlock_irq(q->queue_lock); | |
931 | rcu_read_unlock(); | |
932 | ||
933 | if (preloaded) | |
934 | radix_tree_preload_end(); | |
935 | ||
936 | if (IS_ERR(blkg)) { | |
937 | kfree(new_blkg); | |
938 | return PTR_ERR(blkg); | |
939 | } | |
940 | ||
941 | q->root_blkg = blkg; | |
942 | q->root_rl.blkg = blkg; | |
943 | ||
944 | ret = blk_throtl_init(q); | |
945 | if (ret) { | |
946 | spin_lock_irq(q->queue_lock); | |
947 | blkg_destroy_all(q); | |
948 | spin_unlock_irq(q->queue_lock); | |
949 | } | |
950 | return ret; | |
951 | } | |
952 | ||
953 | /** | |
954 | * blkcg_drain_queue - drain blkcg part of request_queue | |
955 | * @q: request_queue to drain | |
956 | * | |
957 | * Called from blk_drain_queue(). Responsible for draining blkcg part. | |
958 | */ | |
959 | void blkcg_drain_queue(struct request_queue *q) | |
960 | { | |
961 | lockdep_assert_held(q->queue_lock); | |
962 | ||
963 | /* | |
964 | * @q could be exiting and already have destroyed all blkgs as | |
965 | * indicated by NULL root_blkg. If so, don't confuse policies. | |
966 | */ | |
967 | if (!q->root_blkg) | |
968 | return; | |
969 | ||
970 | blk_throtl_drain(q); | |
971 | } | |
972 | ||
973 | /** | |
974 | * blkcg_exit_queue - exit and release blkcg part of request_queue | |
975 | * @q: request_queue being released | |
976 | * | |
977 | * Called from blk_release_queue(). Responsible for exiting blkcg part. | |
978 | */ | |
979 | void blkcg_exit_queue(struct request_queue *q) | |
980 | { | |
981 | spin_lock_irq(q->queue_lock); | |
982 | blkg_destroy_all(q); | |
983 | spin_unlock_irq(q->queue_lock); | |
984 | ||
985 | blk_throtl_exit(q); | |
986 | } | |
987 | ||
988 | /* | |
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. | |
993 | */ | |
994 | static int blkcg_can_attach(struct cgroup_subsys_state *css, | |
995 | struct cgroup_taskset *tset) | |
996 | { | |
997 | struct task_struct *task; | |
998 | struct io_context *ioc; | |
999 | int ret = 0; | |
1000 | ||
1001 | /* task_lock() is needed to avoid races with exit_io_context() */ | |
1002 | cgroup_taskset_for_each(task, tset) { | |
1003 | task_lock(task); | |
1004 | ioc = task->io_context; | |
1005 | if (ioc && atomic_read(&ioc->nr_tasks) > 1) | |
1006 | ret = -EINVAL; | |
1007 | task_unlock(task); | |
1008 | if (ret) | |
1009 | break; | |
1010 | } | |
1011 | return ret; | |
1012 | } | |
1013 | ||
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, | |
1020 | #ifdef CONFIG_MEMCG | |
1021 | /* | |
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. | |
1025 | */ | |
1026 | .depends_on = 1 << memory_cgrp_id, | |
1027 | #endif | |
1028 | }; | |
1029 | EXPORT_SYMBOL_GPL(blkio_cgrp_subsys); | |
1030 | ||
1031 | /** | |
1032 | * blkcg_activate_policy - activate a blkcg policy on a request_queue | |
1033 | * @q: request_queue of interest | |
1034 | * @pol: blkcg policy to activate | |
1035 | * | |
1036 | * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through | |
1037 | * bypass mode to populate its blkgs with policy_data for @pol. | |
1038 | * | |
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. | |
1043 | * | |
1044 | * The caller is responsible for synchronizing [de]activations and policy | |
1045 | * [un]registerations. Returns 0 on success, -errno on failure. | |
1046 | */ | |
1047 | int blkcg_activate_policy(struct request_queue *q, | |
1048 | const struct blkcg_policy *pol) | |
1049 | { | |
1050 | LIST_HEAD(pds); | |
1051 | LIST_HEAD(cpds); | |
1052 | struct blkcg_gq *blkg; | |
1053 | struct blkg_policy_data *pd, *nd; | |
1054 | struct blkcg_policy_data *cpd, *cnd; | |
1055 | int cnt = 0, ret; | |
1056 | ||
1057 | if (blkcg_policy_enabled(q, pol)) | |
1058 | return 0; | |
1059 | ||
1060 | /* count and allocate policy_data for all existing blkgs */ | |
1061 | blk_queue_bypass_start(q); | |
1062 | spin_lock_irq(q->queue_lock); | |
1063 | list_for_each_entry(blkg, &q->blkg_list, q_node) | |
1064 | cnt++; | |
1065 | spin_unlock_irq(q->queue_lock); | |
1066 | ||
1067 | /* | |
1068 | * Allocate per-blkg and per-blkcg policy data | |
1069 | * for all existing blkgs. | |
1070 | */ | |
1071 | while (cnt--) { | |
1072 | pd = kzalloc_node(pol->pd_size, GFP_KERNEL, q->node); | |
1073 | if (!pd) { | |
1074 | ret = -ENOMEM; | |
1075 | goto out_free; | |
1076 | } | |
1077 | list_add_tail(&pd->alloc_node, &pds); | |
1078 | ||
1079 | if (!pol->cpd_size) | |
1080 | continue; | |
1081 | cpd = kzalloc_node(pol->cpd_size, GFP_KERNEL, q->node); | |
1082 | if (!cpd) { | |
1083 | ret = -ENOMEM; | |
1084 | goto out_free; | |
1085 | } | |
1086 | list_add_tail(&cpd->alloc_node, &cpds); | |
1087 | } | |
1088 | ||
1089 | /* | |
1090 | * Install the allocated pds and cpds. With @q bypassing, no new blkg | |
1091 | * should have been created while the queue lock was dropped. | |
1092 | */ | |
1093 | spin_lock_irq(q->queue_lock); | |
1094 | ||
1095 | list_for_each_entry(blkg, &q->blkg_list, q_node) { | |
1096 | if (WARN_ON(list_empty(&pds)) || | |
1097 | WARN_ON(pol->cpd_size && list_empty(&cpds))) { | |
1098 | /* umm... this shouldn't happen, just abort */ | |
1099 | ret = -ENOMEM; | |
1100 | goto out_unlock; | |
1101 | } | |
1102 | cpd = list_first_entry(&cpds, struct blkcg_policy_data, | |
1103 | alloc_node); | |
1104 | list_del_init(&cpd->alloc_node); | |
1105 | pd = list_first_entry(&pds, struct blkg_policy_data, alloc_node); | |
1106 | list_del_init(&pd->alloc_node); | |
1107 | ||
1108 | /* grab blkcg lock too while installing @pd on @blkg */ | |
1109 | spin_lock(&blkg->blkcg->lock); | |
1110 | ||
1111 | if (!pol->cpd_size) | |
1112 | goto no_cpd; | |
1113 | if (!blkg->blkcg->pd[pol->plid]) { | |
1114 | /* Per-policy per-blkcg data */ | |
1115 | blkg->blkcg->pd[pol->plid] = cpd; | |
1116 | cpd->plid = pol->plid; | |
1117 | pol->cpd_init_fn(blkg->blkcg); | |
1118 | } else { /* must free it as it has already been extracted */ | |
1119 | kfree(cpd); | |
1120 | } | |
1121 | no_cpd: | |
1122 | blkg->pd[pol->plid] = pd; | |
1123 | pd->blkg = blkg; | |
1124 | pd->plid = pol->plid; | |
1125 | pol->pd_init_fn(blkg); | |
1126 | ||
1127 | spin_unlock(&blkg->blkcg->lock); | |
1128 | } | |
1129 | ||
1130 | __set_bit(pol->plid, q->blkcg_pols); | |
1131 | ret = 0; | |
1132 | out_unlock: | |
1133 | spin_unlock_irq(q->queue_lock); | |
1134 | out_free: | |
1135 | blk_queue_bypass_end(q); | |
1136 | list_for_each_entry_safe(pd, nd, &pds, alloc_node) | |
1137 | kfree(pd); | |
1138 | list_for_each_entry_safe(cpd, cnd, &cpds, alloc_node) | |
1139 | kfree(cpd); | |
1140 | return ret; | |
1141 | } | |
1142 | EXPORT_SYMBOL_GPL(blkcg_activate_policy); | |
1143 | ||
1144 | /** | |
1145 | * blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue | |
1146 | * @q: request_queue of interest | |
1147 | * @pol: blkcg policy to deactivate | |
1148 | * | |
1149 | * Deactivate @pol on @q. Follows the same synchronization rules as | |
1150 | * blkcg_activate_policy(). | |
1151 | */ | |
1152 | void blkcg_deactivate_policy(struct request_queue *q, | |
1153 | const struct blkcg_policy *pol) | |
1154 | { | |
1155 | struct blkcg_gq *blkg; | |
1156 | ||
1157 | if (!blkcg_policy_enabled(q, pol)) | |
1158 | return; | |
1159 | ||
1160 | blk_queue_bypass_start(q); | |
1161 | spin_lock_irq(q->queue_lock); | |
1162 | ||
1163 | __clear_bit(pol->plid, q->blkcg_pols); | |
1164 | ||
1165 | list_for_each_entry(blkg, &q->blkg_list, q_node) { | |
1166 | /* grab blkcg lock too while removing @pd from @blkg */ | |
1167 | spin_lock(&blkg->blkcg->lock); | |
1168 | ||
1169 | if (pol->pd_offline_fn) | |
1170 | pol->pd_offline_fn(blkg); | |
1171 | if (pol->pd_exit_fn) | |
1172 | pol->pd_exit_fn(blkg); | |
1173 | ||
1174 | kfree(blkg->pd[pol->plid]); | |
1175 | blkg->pd[pol->plid] = NULL; | |
1176 | ||
1177 | spin_unlock(&blkg->blkcg->lock); | |
1178 | } | |
1179 | ||
1180 | spin_unlock_irq(q->queue_lock); | |
1181 | blk_queue_bypass_end(q); | |
1182 | } | |
1183 | EXPORT_SYMBOL_GPL(blkcg_deactivate_policy); | |
1184 | ||
1185 | /** | |
1186 | * blkcg_policy_register - register a blkcg policy | |
1187 | * @pol: blkcg policy to register | |
1188 | * | |
1189 | * Register @pol with blkcg core. Might sleep and @pol may be modified on | |
1190 | * successful registration. Returns 0 on success and -errno on failure. | |
1191 | */ | |
1192 | int blkcg_policy_register(struct blkcg_policy *pol) | |
1193 | { | |
1194 | int i, ret; | |
1195 | ||
1196 | if (WARN_ON(pol->pd_size < sizeof(struct blkg_policy_data))) | |
1197 | return -EINVAL; | |
1198 | ||
1199 | mutex_lock(&blkcg_pol_register_mutex); | |
1200 | mutex_lock(&blkcg_pol_mutex); | |
1201 | ||
1202 | /* find an empty slot */ | |
1203 | ret = -ENOSPC; | |
1204 | for (i = 0; i < BLKCG_MAX_POLS; i++) | |
1205 | if (!blkcg_policy[i]) | |
1206 | break; | |
1207 | if (i >= BLKCG_MAX_POLS) | |
1208 | goto err_unlock; | |
1209 | ||
1210 | /* register and update blkgs */ | |
1211 | pol->plid = i; | |
1212 | blkcg_policy[i] = pol; | |
1213 | mutex_unlock(&blkcg_pol_mutex); | |
1214 | ||
1215 | /* everything is in place, add intf files for the new policy */ | |
1216 | if (pol->cftypes) | |
1217 | WARN_ON(cgroup_add_legacy_cftypes(&blkio_cgrp_subsys, | |
1218 | pol->cftypes)); | |
1219 | mutex_unlock(&blkcg_pol_register_mutex); | |
1220 | return 0; | |
1221 | ||
1222 | err_unlock: | |
1223 | mutex_unlock(&blkcg_pol_mutex); | |
1224 | mutex_unlock(&blkcg_pol_register_mutex); | |
1225 | return ret; | |
1226 | } | |
1227 | EXPORT_SYMBOL_GPL(blkcg_policy_register); | |
1228 | ||
1229 | /** | |
1230 | * blkcg_policy_unregister - unregister a blkcg policy | |
1231 | * @pol: blkcg policy to unregister | |
1232 | * | |
1233 | * Undo blkcg_policy_register(@pol). Might sleep. | |
1234 | */ | |
1235 | void blkcg_policy_unregister(struct blkcg_policy *pol) | |
1236 | { | |
1237 | mutex_lock(&blkcg_pol_register_mutex); | |
1238 | ||
1239 | if (WARN_ON(blkcg_policy[pol->plid] != pol)) | |
1240 | goto out_unlock; | |
1241 | ||
1242 | /* kill the intf files first */ | |
1243 | if (pol->cftypes) | |
1244 | cgroup_rm_cftypes(pol->cftypes); | |
1245 | ||
1246 | /* unregister and update blkgs */ | |
1247 | mutex_lock(&blkcg_pol_mutex); | |
1248 | blkcg_policy[pol->plid] = NULL; | |
1249 | mutex_unlock(&blkcg_pol_mutex); | |
1250 | out_unlock: | |
1251 | mutex_unlock(&blkcg_pol_register_mutex); | |
1252 | } | |
1253 | EXPORT_SYMBOL_GPL(blkcg_policy_unregister); |