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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/ctype.h> | |
28 | #include <linux/blk-cgroup.h> | |
29 | #include "blk.h" | |
30 | ||
31 | #define MAX_KEY_LEN 100 | |
32 | ||
33 | /* | |
34 | * blkcg_pol_mutex protects blkcg_policy[] and policy [de]activation. | |
35 | * blkcg_pol_register_mutex nests outside of it and synchronizes entire | |
36 | * policy [un]register operations including cgroup file additions / | |
37 | * removals. Putting cgroup file registration outside blkcg_pol_mutex | |
38 | * allows grabbing it from cgroup callbacks. | |
39 | */ | |
40 | static DEFINE_MUTEX(blkcg_pol_register_mutex); | |
41 | static DEFINE_MUTEX(blkcg_pol_mutex); | |
42 | ||
43 | struct blkcg blkcg_root; | |
44 | EXPORT_SYMBOL_GPL(blkcg_root); | |
45 | ||
46 | struct cgroup_subsys_state * const blkcg_root_css = &blkcg_root.css; | |
47 | ||
48 | static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS]; | |
49 | ||
50 | static LIST_HEAD(all_blkcgs); /* protected by blkcg_pol_mutex */ | |
51 | ||
52 | static bool blkcg_policy_enabled(struct request_queue *q, | |
53 | const struct blkcg_policy *pol) | |
54 | { | |
55 | return pol && test_bit(pol->plid, q->blkcg_pols); | |
56 | } | |
57 | ||
58 | /** | |
59 | * blkg_free - free a blkg | |
60 | * @blkg: blkg to free | |
61 | * | |
62 | * Free @blkg which may be partially allocated. | |
63 | */ | |
64 | static void blkg_free(struct blkcg_gq *blkg) | |
65 | { | |
66 | int i; | |
67 | ||
68 | if (!blkg) | |
69 | return; | |
70 | ||
71 | for (i = 0; i < BLKCG_MAX_POLS; i++) | |
72 | if (blkg->pd[i]) | |
73 | blkcg_policy[i]->pd_free_fn(blkg->pd[i]); | |
74 | ||
75 | if (blkg->blkcg != &blkcg_root) | |
76 | blk_exit_rl(&blkg->rl); | |
77 | ||
78 | blkg_rwstat_exit(&blkg->stat_ios); | |
79 | blkg_rwstat_exit(&blkg->stat_bytes); | |
80 | kfree(blkg); | |
81 | } | |
82 | ||
83 | /** | |
84 | * blkg_alloc - allocate a blkg | |
85 | * @blkcg: block cgroup the new blkg is associated with | |
86 | * @q: request_queue the new blkg is associated with | |
87 | * @gfp_mask: allocation mask to use | |
88 | * | |
89 | * Allocate a new blkg assocating @blkcg and @q. | |
90 | */ | |
91 | static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, | |
92 | gfp_t gfp_mask) | |
93 | { | |
94 | struct blkcg_gq *blkg; | |
95 | int i; | |
96 | ||
97 | /* alloc and init base part */ | |
98 | blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node); | |
99 | if (!blkg) | |
100 | return NULL; | |
101 | ||
102 | if (blkg_rwstat_init(&blkg->stat_bytes, gfp_mask) || | |
103 | blkg_rwstat_init(&blkg->stat_ios, gfp_mask)) | |
104 | goto err_free; | |
105 | ||
106 | blkg->q = q; | |
107 | INIT_LIST_HEAD(&blkg->q_node); | |
108 | blkg->blkcg = blkcg; | |
109 | atomic_set(&blkg->refcnt, 1); | |
110 | ||
111 | /* root blkg uses @q->root_rl, init rl only for !root blkgs */ | |
112 | if (blkcg != &blkcg_root) { | |
113 | if (blk_init_rl(&blkg->rl, q, gfp_mask)) | |
114 | goto err_free; | |
115 | blkg->rl.blkg = blkg; | |
116 | } | |
117 | ||
118 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
119 | struct blkcg_policy *pol = blkcg_policy[i]; | |
120 | struct blkg_policy_data *pd; | |
121 | ||
122 | if (!blkcg_policy_enabled(q, pol)) | |
123 | continue; | |
124 | ||
125 | /* alloc per-policy data and attach it to blkg */ | |
126 | pd = pol->pd_alloc_fn(gfp_mask, q->node); | |
127 | if (!pd) | |
128 | goto err_free; | |
129 | ||
130 | blkg->pd[i] = pd; | |
131 | pd->blkg = blkg; | |
132 | pd->plid = i; | |
133 | } | |
134 | ||
135 | return blkg; | |
136 | ||
137 | err_free: | |
138 | blkg_free(blkg); | |
139 | return NULL; | |
140 | } | |
141 | ||
142 | struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg, | |
143 | struct request_queue *q, bool update_hint) | |
144 | { | |
145 | struct blkcg_gq *blkg; | |
146 | ||
147 | /* | |
148 | * Hint didn't match. Look up from the radix tree. Note that the | |
149 | * hint can only be updated under queue_lock as otherwise @blkg | |
150 | * could have already been removed from blkg_tree. The caller is | |
151 | * responsible for grabbing queue_lock if @update_hint. | |
152 | */ | |
153 | blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); | |
154 | if (blkg && blkg->q == q) { | |
155 | if (update_hint) { | |
156 | lockdep_assert_held(q->queue_lock); | |
157 | rcu_assign_pointer(blkcg->blkg_hint, blkg); | |
158 | } | |
159 | return blkg; | |
160 | } | |
161 | ||
162 | return NULL; | |
163 | } | |
164 | EXPORT_SYMBOL_GPL(blkg_lookup_slowpath); | |
165 | ||
166 | /* | |
167 | * If @new_blkg is %NULL, this function tries to allocate a new one as | |
168 | * necessary using %GFP_NOWAIT. @new_blkg is always consumed on return. | |
169 | */ | |
170 | static struct blkcg_gq *blkg_create(struct blkcg *blkcg, | |
171 | struct request_queue *q, | |
172 | struct blkcg_gq *new_blkg) | |
173 | { | |
174 | struct blkcg_gq *blkg; | |
175 | struct bdi_writeback_congested *wb_congested; | |
176 | int i, ret; | |
177 | ||
178 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
179 | lockdep_assert_held(q->queue_lock); | |
180 | ||
181 | /* blkg holds a reference to blkcg */ | |
182 | if (!css_tryget_online(&blkcg->css)) { | |
183 | ret = -ENODEV; | |
184 | goto err_free_blkg; | |
185 | } | |
186 | ||
187 | wb_congested = wb_congested_get_create(&q->backing_dev_info, | |
188 | blkcg->css.id, | |
189 | GFP_NOWAIT | __GFP_NOWARN); | |
190 | if (!wb_congested) { | |
191 | ret = -ENOMEM; | |
192 | goto err_put_css; | |
193 | } | |
194 | ||
195 | /* allocate */ | |
196 | if (!new_blkg) { | |
197 | new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT | __GFP_NOWARN); | |
198 | if (unlikely(!new_blkg)) { | |
199 | ret = -ENOMEM; | |
200 | goto err_put_congested; | |
201 | } | |
202 | } | |
203 | blkg = new_blkg; | |
204 | blkg->wb_congested = wb_congested; | |
205 | ||
206 | /* link parent */ | |
207 | if (blkcg_parent(blkcg)) { | |
208 | blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false); | |
209 | if (WARN_ON_ONCE(!blkg->parent)) { | |
210 | ret = -ENODEV; | |
211 | goto err_put_congested; | |
212 | } | |
213 | blkg_get(blkg->parent); | |
214 | } | |
215 | ||
216 | /* invoke per-policy init */ | |
217 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
218 | struct blkcg_policy *pol = blkcg_policy[i]; | |
219 | ||
220 | if (blkg->pd[i] && pol->pd_init_fn) | |
221 | pol->pd_init_fn(blkg->pd[i]); | |
222 | } | |
223 | ||
224 | /* insert */ | |
225 | spin_lock(&blkcg->lock); | |
226 | ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg); | |
227 | if (likely(!ret)) { | |
228 | hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); | |
229 | list_add(&blkg->q_node, &q->blkg_list); | |
230 | ||
231 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
232 | struct blkcg_policy *pol = blkcg_policy[i]; | |
233 | ||
234 | if (blkg->pd[i] && pol->pd_online_fn) | |
235 | pol->pd_online_fn(blkg->pd[i]); | |
236 | } | |
237 | } | |
238 | blkg->online = true; | |
239 | spin_unlock(&blkcg->lock); | |
240 | ||
241 | if (!ret) | |
242 | return blkg; | |
243 | ||
244 | /* @blkg failed fully initialized, use the usual release path */ | |
245 | blkg_put(blkg); | |
246 | return ERR_PTR(ret); | |
247 | ||
248 | err_put_congested: | |
249 | wb_congested_put(wb_congested); | |
250 | err_put_css: | |
251 | css_put(&blkcg->css); | |
252 | err_free_blkg: | |
253 | blkg_free(new_blkg); | |
254 | return ERR_PTR(ret); | |
255 | } | |
256 | ||
257 | /** | |
258 | * blkg_lookup_create - lookup blkg, try to create one if not there | |
259 | * @blkcg: blkcg of interest | |
260 | * @q: request_queue of interest | |
261 | * | |
262 | * Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to | |
263 | * create one. blkg creation is performed recursively from blkcg_root such | |
264 | * that all non-root blkg's have access to the parent blkg. This function | |
265 | * should be called under RCU read lock and @q->queue_lock. | |
266 | * | |
267 | * Returns pointer to the looked up or created blkg on success, ERR_PTR() | |
268 | * value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not | |
269 | * dead and bypassing, returns ERR_PTR(-EBUSY). | |
270 | */ | |
271 | struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, | |
272 | struct request_queue *q) | |
273 | { | |
274 | struct blkcg_gq *blkg; | |
275 | ||
276 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
277 | lockdep_assert_held(q->queue_lock); | |
278 | ||
279 | /* | |
280 | * This could be the first entry point of blkcg implementation and | |
281 | * we shouldn't allow anything to go through for a bypassing queue. | |
282 | */ | |
283 | if (unlikely(blk_queue_bypass(q))) | |
284 | return ERR_PTR(blk_queue_dying(q) ? -ENODEV : -EBUSY); | |
285 | ||
286 | blkg = __blkg_lookup(blkcg, q, true); | |
287 | if (blkg) | |
288 | return blkg; | |
289 | ||
290 | /* | |
291 | * Create blkgs walking down from blkcg_root to @blkcg, so that all | |
292 | * non-root blkgs have access to their parents. | |
293 | */ | |
294 | while (true) { | |
295 | struct blkcg *pos = blkcg; | |
296 | struct blkcg *parent = blkcg_parent(blkcg); | |
297 | ||
298 | while (parent && !__blkg_lookup(parent, q, false)) { | |
299 | pos = parent; | |
300 | parent = blkcg_parent(parent); | |
301 | } | |
302 | ||
303 | blkg = blkg_create(pos, q, NULL); | |
304 | if (pos == blkcg || IS_ERR(blkg)) | |
305 | return blkg; | |
306 | } | |
307 | } | |
308 | ||
309 | static void blkg_destroy(struct blkcg_gq *blkg) | |
310 | { | |
311 | struct blkcg *blkcg = blkg->blkcg; | |
312 | struct blkcg_gq *parent = blkg->parent; | |
313 | int i; | |
314 | ||
315 | lockdep_assert_held(blkg->q->queue_lock); | |
316 | lockdep_assert_held(&blkcg->lock); | |
317 | ||
318 | /* Something wrong if we are trying to remove same group twice */ | |
319 | WARN_ON_ONCE(list_empty(&blkg->q_node)); | |
320 | WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node)); | |
321 | ||
322 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
323 | struct blkcg_policy *pol = blkcg_policy[i]; | |
324 | ||
325 | if (blkg->pd[i] && pol->pd_offline_fn) | |
326 | pol->pd_offline_fn(blkg->pd[i]); | |
327 | } | |
328 | ||
329 | if (parent) { | |
330 | blkg_rwstat_add_aux(&parent->stat_bytes, &blkg->stat_bytes); | |
331 | blkg_rwstat_add_aux(&parent->stat_ios, &blkg->stat_ios); | |
332 | } | |
333 | ||
334 | blkg->online = false; | |
335 | ||
336 | radix_tree_delete(&blkcg->blkg_tree, blkg->q->id); | |
337 | list_del_init(&blkg->q_node); | |
338 | hlist_del_init_rcu(&blkg->blkcg_node); | |
339 | ||
340 | /* | |
341 | * Both setting lookup hint to and clearing it from @blkg are done | |
342 | * under queue_lock. If it's not pointing to @blkg now, it never | |
343 | * will. Hint assignment itself can race safely. | |
344 | */ | |
345 | if (rcu_access_pointer(blkcg->blkg_hint) == blkg) | |
346 | rcu_assign_pointer(blkcg->blkg_hint, NULL); | |
347 | ||
348 | /* | |
349 | * Put the reference taken at the time of creation so that when all | |
350 | * queues are gone, group can be destroyed. | |
351 | */ | |
352 | blkg_put(blkg); | |
353 | } | |
354 | ||
355 | /** | |
356 | * blkg_destroy_all - destroy all blkgs associated with a request_queue | |
357 | * @q: request_queue of interest | |
358 | * | |
359 | * Destroy all blkgs associated with @q. | |
360 | */ | |
361 | static void blkg_destroy_all(struct request_queue *q) | |
362 | { | |
363 | struct blkcg_gq *blkg, *n; | |
364 | ||
365 | lockdep_assert_held(q->queue_lock); | |
366 | ||
367 | list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { | |
368 | struct blkcg *blkcg = blkg->blkcg; | |
369 | ||
370 | spin_lock(&blkcg->lock); | |
371 | blkg_destroy(blkg); | |
372 | spin_unlock(&blkcg->lock); | |
373 | } | |
374 | ||
375 | q->root_blkg = NULL; | |
376 | q->root_rl.blkg = NULL; | |
377 | } | |
378 | ||
379 | /* | |
380 | * A group is RCU protected, but having an rcu lock does not mean that one | |
381 | * can access all the fields of blkg and assume these are valid. For | |
382 | * example, don't try to follow throtl_data and request queue links. | |
383 | * | |
384 | * Having a reference to blkg under an rcu allows accesses to only values | |
385 | * local to groups like group stats and group rate limits. | |
386 | */ | |
387 | void __blkg_release_rcu(struct rcu_head *rcu_head) | |
388 | { | |
389 | struct blkcg_gq *blkg = container_of(rcu_head, struct blkcg_gq, rcu_head); | |
390 | ||
391 | /* release the blkcg and parent blkg refs this blkg has been holding */ | |
392 | css_put(&blkg->blkcg->css); | |
393 | if (blkg->parent) | |
394 | blkg_put(blkg->parent); | |
395 | ||
396 | wb_congested_put(blkg->wb_congested); | |
397 | ||
398 | blkg_free(blkg); | |
399 | } | |
400 | EXPORT_SYMBOL_GPL(__blkg_release_rcu); | |
401 | ||
402 | /* | |
403 | * The next function used by blk_queue_for_each_rl(). It's a bit tricky | |
404 | * because the root blkg uses @q->root_rl instead of its own rl. | |
405 | */ | |
406 | struct request_list *__blk_queue_next_rl(struct request_list *rl, | |
407 | struct request_queue *q) | |
408 | { | |
409 | struct list_head *ent; | |
410 | struct blkcg_gq *blkg; | |
411 | ||
412 | /* | |
413 | * Determine the current blkg list_head. The first entry is | |
414 | * root_rl which is off @q->blkg_list and mapped to the head. | |
415 | */ | |
416 | if (rl == &q->root_rl) { | |
417 | ent = &q->blkg_list; | |
418 | /* There are no more block groups, hence no request lists */ | |
419 | if (list_empty(ent)) | |
420 | return NULL; | |
421 | } else { | |
422 | blkg = container_of(rl, struct blkcg_gq, rl); | |
423 | ent = &blkg->q_node; | |
424 | } | |
425 | ||
426 | /* walk to the next list_head, skip root blkcg */ | |
427 | ent = ent->next; | |
428 | if (ent == &q->root_blkg->q_node) | |
429 | ent = ent->next; | |
430 | if (ent == &q->blkg_list) | |
431 | return NULL; | |
432 | ||
433 | blkg = container_of(ent, struct blkcg_gq, q_node); | |
434 | return &blkg->rl; | |
435 | } | |
436 | ||
437 | static int blkcg_reset_stats(struct cgroup_subsys_state *css, | |
438 | struct cftype *cftype, u64 val) | |
439 | { | |
440 | struct blkcg *blkcg = css_to_blkcg(css); | |
441 | struct blkcg_gq *blkg; | |
442 | int i; | |
443 | ||
444 | mutex_lock(&blkcg_pol_mutex); | |
445 | spin_lock_irq(&blkcg->lock); | |
446 | ||
447 | /* | |
448 | * Note that stat reset is racy - it doesn't synchronize against | |
449 | * stat updates. This is a debug feature which shouldn't exist | |
450 | * anyway. If you get hit by a race, retry. | |
451 | */ | |
452 | hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { | |
453 | blkg_rwstat_reset(&blkg->stat_bytes); | |
454 | blkg_rwstat_reset(&blkg->stat_ios); | |
455 | ||
456 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
457 | struct blkcg_policy *pol = blkcg_policy[i]; | |
458 | ||
459 | if (blkg->pd[i] && pol->pd_reset_stats_fn) | |
460 | pol->pd_reset_stats_fn(blkg->pd[i]); | |
461 | } | |
462 | } | |
463 | ||
464 | spin_unlock_irq(&blkcg->lock); | |
465 | mutex_unlock(&blkcg_pol_mutex); | |
466 | return 0; | |
467 | } | |
468 | ||
469 | const char *blkg_dev_name(struct blkcg_gq *blkg) | |
470 | { | |
471 | /* some drivers (floppy) instantiate a queue w/o disk registered */ | |
472 | if (blkg->q->backing_dev_info.dev) | |
473 | return dev_name(blkg->q->backing_dev_info.dev); | |
474 | return NULL; | |
475 | } | |
476 | EXPORT_SYMBOL_GPL(blkg_dev_name); | |
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)atomic64_read(&rwstat->aux_cnt[i])); | |
566 | ||
567 | v = atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_READ]) + | |
568 | atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_WRITE]); | |
569 | seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v); | |
570 | return v; | |
571 | } | |
572 | EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat); | |
573 | ||
574 | /** | |
575 | * blkg_prfill_stat - prfill callback for blkg_stat | |
576 | * @sf: seq_file to print to | |
577 | * @pd: policy private data of interest | |
578 | * @off: offset to the blkg_stat in @pd | |
579 | * | |
580 | * prfill callback for printing a blkg_stat. | |
581 | */ | |
582 | u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off) | |
583 | { | |
584 | return __blkg_prfill_u64(sf, pd, blkg_stat_read((void *)pd + off)); | |
585 | } | |
586 | EXPORT_SYMBOL_GPL(blkg_prfill_stat); | |
587 | ||
588 | /** | |
589 | * blkg_prfill_rwstat - prfill callback for blkg_rwstat | |
590 | * @sf: seq_file to print to | |
591 | * @pd: policy private data of interest | |
592 | * @off: offset to the blkg_rwstat in @pd | |
593 | * | |
594 | * prfill callback for printing a blkg_rwstat. | |
595 | */ | |
596 | u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, | |
597 | int off) | |
598 | { | |
599 | struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd + off); | |
600 | ||
601 | return __blkg_prfill_rwstat(sf, pd, &rwstat); | |
602 | } | |
603 | EXPORT_SYMBOL_GPL(blkg_prfill_rwstat); | |
604 | ||
605 | static u64 blkg_prfill_rwstat_field(struct seq_file *sf, | |
606 | struct blkg_policy_data *pd, int off) | |
607 | { | |
608 | struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd->blkg + off); | |
609 | ||
610 | return __blkg_prfill_rwstat(sf, pd, &rwstat); | |
611 | } | |
612 | ||
613 | /** | |
614 | * blkg_print_stat_bytes - seq_show callback for blkg->stat_bytes | |
615 | * @sf: seq_file to print to | |
616 | * @v: unused | |
617 | * | |
618 | * To be used as cftype->seq_show to print blkg->stat_bytes. | |
619 | * cftype->private must be set to the blkcg_policy. | |
620 | */ | |
621 | int blkg_print_stat_bytes(struct seq_file *sf, void *v) | |
622 | { | |
623 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), | |
624 | blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private, | |
625 | offsetof(struct blkcg_gq, stat_bytes), true); | |
626 | return 0; | |
627 | } | |
628 | EXPORT_SYMBOL_GPL(blkg_print_stat_bytes); | |
629 | ||
630 | /** | |
631 | * blkg_print_stat_bytes - seq_show callback for blkg->stat_ios | |
632 | * @sf: seq_file to print to | |
633 | * @v: unused | |
634 | * | |
635 | * To be used as cftype->seq_show to print blkg->stat_ios. cftype->private | |
636 | * must be set to the blkcg_policy. | |
637 | */ | |
638 | int blkg_print_stat_ios(struct seq_file *sf, void *v) | |
639 | { | |
640 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), | |
641 | blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private, | |
642 | offsetof(struct blkcg_gq, stat_ios), true); | |
643 | return 0; | |
644 | } | |
645 | EXPORT_SYMBOL_GPL(blkg_print_stat_ios); | |
646 | ||
647 | static u64 blkg_prfill_rwstat_field_recursive(struct seq_file *sf, | |
648 | struct blkg_policy_data *pd, | |
649 | int off) | |
650 | { | |
651 | struct blkg_rwstat rwstat = blkg_rwstat_recursive_sum(pd->blkg, | |
652 | NULL, off); | |
653 | return __blkg_prfill_rwstat(sf, pd, &rwstat); | |
654 | } | |
655 | ||
656 | /** | |
657 | * blkg_print_stat_bytes_recursive - recursive version of blkg_print_stat_bytes | |
658 | * @sf: seq_file to print to | |
659 | * @v: unused | |
660 | */ | |
661 | int blkg_print_stat_bytes_recursive(struct seq_file *sf, void *v) | |
662 | { | |
663 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), | |
664 | blkg_prfill_rwstat_field_recursive, | |
665 | (void *)seq_cft(sf)->private, | |
666 | offsetof(struct blkcg_gq, stat_bytes), true); | |
667 | return 0; | |
668 | } | |
669 | EXPORT_SYMBOL_GPL(blkg_print_stat_bytes_recursive); | |
670 | ||
671 | /** | |
672 | * blkg_print_stat_ios_recursive - recursive version of blkg_print_stat_ios | |
673 | * @sf: seq_file to print to | |
674 | * @v: unused | |
675 | */ | |
676 | int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v) | |
677 | { | |
678 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), | |
679 | blkg_prfill_rwstat_field_recursive, | |
680 | (void *)seq_cft(sf)->private, | |
681 | offsetof(struct blkcg_gq, stat_ios), true); | |
682 | return 0; | |
683 | } | |
684 | EXPORT_SYMBOL_GPL(blkg_print_stat_ios_recursive); | |
685 | ||
686 | /** | |
687 | * blkg_stat_recursive_sum - collect hierarchical blkg_stat | |
688 | * @blkg: blkg of interest | |
689 | * @pol: blkcg_policy which contains the blkg_stat | |
690 | * @off: offset to the blkg_stat in blkg_policy_data or @blkg | |
691 | * | |
692 | * Collect the blkg_stat specified by @blkg, @pol and @off and all its | |
693 | * online descendants and their aux counts. The caller must be holding the | |
694 | * queue lock for online tests. | |
695 | * | |
696 | * If @pol is NULL, blkg_stat is at @off bytes into @blkg; otherwise, it is | |
697 | * at @off bytes into @blkg's blkg_policy_data of the policy. | |
698 | */ | |
699 | u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg, | |
700 | struct blkcg_policy *pol, int off) | |
701 | { | |
702 | struct blkcg_gq *pos_blkg; | |
703 | struct cgroup_subsys_state *pos_css; | |
704 | u64 sum = 0; | |
705 | ||
706 | lockdep_assert_held(blkg->q->queue_lock); | |
707 | ||
708 | rcu_read_lock(); | |
709 | blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) { | |
710 | struct blkg_stat *stat; | |
711 | ||
712 | if (!pos_blkg->online) | |
713 | continue; | |
714 | ||
715 | if (pol) | |
716 | stat = (void *)blkg_to_pd(pos_blkg, pol) + off; | |
717 | else | |
718 | stat = (void *)blkg + off; | |
719 | ||
720 | sum += blkg_stat_read(stat) + atomic64_read(&stat->aux_cnt); | |
721 | } | |
722 | rcu_read_unlock(); | |
723 | ||
724 | return sum; | |
725 | } | |
726 | EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum); | |
727 | ||
728 | /** | |
729 | * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat | |
730 | * @blkg: blkg of interest | |
731 | * @pol: blkcg_policy which contains the blkg_rwstat | |
732 | * @off: offset to the blkg_rwstat in blkg_policy_data or @blkg | |
733 | * | |
734 | * Collect the blkg_rwstat specified by @blkg, @pol and @off and all its | |
735 | * online descendants and their aux counts. The caller must be holding the | |
736 | * queue lock for online tests. | |
737 | * | |
738 | * If @pol is NULL, blkg_rwstat is at @off bytes into @blkg; otherwise, it | |
739 | * is at @off bytes into @blkg's blkg_policy_data of the policy. | |
740 | */ | |
741 | struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, | |
742 | struct blkcg_policy *pol, int off) | |
743 | { | |
744 | struct blkcg_gq *pos_blkg; | |
745 | struct cgroup_subsys_state *pos_css; | |
746 | struct blkg_rwstat sum = { }; | |
747 | int i; | |
748 | ||
749 | lockdep_assert_held(blkg->q->queue_lock); | |
750 | ||
751 | rcu_read_lock(); | |
752 | blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) { | |
753 | struct blkg_rwstat *rwstat; | |
754 | ||
755 | if (!pos_blkg->online) | |
756 | continue; | |
757 | ||
758 | if (pol) | |
759 | rwstat = (void *)blkg_to_pd(pos_blkg, pol) + off; | |
760 | else | |
761 | rwstat = (void *)pos_blkg + off; | |
762 | ||
763 | for (i = 0; i < BLKG_RWSTAT_NR; i++) | |
764 | atomic64_add(atomic64_read(&rwstat->aux_cnt[i]) + | |
765 | percpu_counter_sum_positive(&rwstat->cpu_cnt[i]), | |
766 | &sum.aux_cnt[i]); | |
767 | } | |
768 | rcu_read_unlock(); | |
769 | ||
770 | return sum; | |
771 | } | |
772 | EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum); | |
773 | ||
774 | /** | |
775 | * blkg_conf_prep - parse and prepare for per-blkg config update | |
776 | * @blkcg: target block cgroup | |
777 | * @pol: target policy | |
778 | * @input: input string | |
779 | * @ctx: blkg_conf_ctx to be filled | |
780 | * | |
781 | * Parse per-blkg config update from @input and initialize @ctx with the | |
782 | * result. @ctx->blkg points to the blkg to be updated and @ctx->body the | |
783 | * part of @input following MAJ:MIN. This function returns with RCU read | |
784 | * lock and queue lock held and must be paired with blkg_conf_finish(). | |
785 | */ | |
786 | int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, | |
787 | char *input, struct blkg_conf_ctx *ctx) | |
788 | __acquires(rcu) __acquires(disk->queue->queue_lock) | |
789 | { | |
790 | struct gendisk *disk; | |
791 | struct blkcg_gq *blkg; | |
792 | struct module *owner; | |
793 | unsigned int major, minor; | |
794 | int key_len, part, ret; | |
795 | char *body; | |
796 | ||
797 | if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2) | |
798 | return -EINVAL; | |
799 | ||
800 | body = input + key_len; | |
801 | if (!isspace(*body)) | |
802 | return -EINVAL; | |
803 | body = skip_spaces(body); | |
804 | ||
805 | disk = get_gendisk(MKDEV(major, minor), &part); | |
806 | if (!disk) | |
807 | return -ENODEV; | |
808 | if (part) { | |
809 | owner = disk->fops->owner; | |
810 | put_disk(disk); | |
811 | module_put(owner); | |
812 | return -ENODEV; | |
813 | } | |
814 | ||
815 | rcu_read_lock(); | |
816 | spin_lock_irq(disk->queue->queue_lock); | |
817 | ||
818 | if (blkcg_policy_enabled(disk->queue, pol)) | |
819 | blkg = blkg_lookup_create(blkcg, disk->queue); | |
820 | else | |
821 | blkg = ERR_PTR(-EOPNOTSUPP); | |
822 | ||
823 | if (IS_ERR(blkg)) { | |
824 | ret = PTR_ERR(blkg); | |
825 | rcu_read_unlock(); | |
826 | spin_unlock_irq(disk->queue->queue_lock); | |
827 | owner = disk->fops->owner; | |
828 | put_disk(disk); | |
829 | module_put(owner); | |
830 | /* | |
831 | * If queue was bypassing, we should retry. Do so after a | |
832 | * short msleep(). It isn't strictly necessary but queue | |
833 | * can be bypassing for some time and it's always nice to | |
834 | * avoid busy looping. | |
835 | */ | |
836 | if (ret == -EBUSY) { | |
837 | msleep(10); | |
838 | ret = restart_syscall(); | |
839 | } | |
840 | return ret; | |
841 | } | |
842 | ||
843 | ctx->disk = disk; | |
844 | ctx->blkg = blkg; | |
845 | ctx->body = body; | |
846 | return 0; | |
847 | } | |
848 | EXPORT_SYMBOL_GPL(blkg_conf_prep); | |
849 | ||
850 | /** | |
851 | * blkg_conf_finish - finish up per-blkg config update | |
852 | * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep() | |
853 | * | |
854 | * Finish up after per-blkg config update. This function must be paired | |
855 | * with blkg_conf_prep(). | |
856 | */ | |
857 | void blkg_conf_finish(struct blkg_conf_ctx *ctx) | |
858 | __releases(ctx->disk->queue->queue_lock) __releases(rcu) | |
859 | { | |
860 | struct module *owner; | |
861 | ||
862 | spin_unlock_irq(ctx->disk->queue->queue_lock); | |
863 | rcu_read_unlock(); | |
864 | owner = ctx->disk->fops->owner; | |
865 | put_disk(ctx->disk); | |
866 | module_put(owner); | |
867 | } | |
868 | EXPORT_SYMBOL_GPL(blkg_conf_finish); | |
869 | ||
870 | static int blkcg_print_stat(struct seq_file *sf, void *v) | |
871 | { | |
872 | struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); | |
873 | struct blkcg_gq *blkg; | |
874 | ||
875 | rcu_read_lock(); | |
876 | ||
877 | hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { | |
878 | const char *dname; | |
879 | struct blkg_rwstat rwstat; | |
880 | u64 rbytes, wbytes, rios, wios; | |
881 | ||
882 | dname = blkg_dev_name(blkg); | |
883 | if (!dname) | |
884 | continue; | |
885 | ||
886 | spin_lock_irq(blkg->q->queue_lock); | |
887 | ||
888 | rwstat = blkg_rwstat_recursive_sum(blkg, NULL, | |
889 | offsetof(struct blkcg_gq, stat_bytes)); | |
890 | rbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]); | |
891 | wbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]); | |
892 | ||
893 | rwstat = blkg_rwstat_recursive_sum(blkg, NULL, | |
894 | offsetof(struct blkcg_gq, stat_ios)); | |
895 | rios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]); | |
896 | wios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]); | |
897 | ||
898 | spin_unlock_irq(blkg->q->queue_lock); | |
899 | ||
900 | if (rbytes || wbytes || rios || wios) | |
901 | seq_printf(sf, "%s rbytes=%llu wbytes=%llu rios=%llu wios=%llu\n", | |
902 | dname, rbytes, wbytes, rios, wios); | |
903 | } | |
904 | ||
905 | rcu_read_unlock(); | |
906 | return 0; | |
907 | } | |
908 | ||
909 | static struct cftype blkcg_files[] = { | |
910 | { | |
911 | .name = "stat", | |
912 | .flags = CFTYPE_NOT_ON_ROOT, | |
913 | .seq_show = blkcg_print_stat, | |
914 | }, | |
915 | { } /* terminate */ | |
916 | }; | |
917 | ||
918 | static struct cftype blkcg_legacy_files[] = { | |
919 | { | |
920 | .name = "reset_stats", | |
921 | .write_u64 = blkcg_reset_stats, | |
922 | }, | |
923 | { } /* terminate */ | |
924 | }; | |
925 | ||
926 | /** | |
927 | * blkcg_css_offline - cgroup css_offline callback | |
928 | * @css: css of interest | |
929 | * | |
930 | * This function is called when @css is about to go away and responsible | |
931 | * for shooting down all blkgs associated with @css. blkgs should be | |
932 | * removed while holding both q and blkcg locks. As blkcg lock is nested | |
933 | * inside q lock, this function performs reverse double lock dancing. | |
934 | * | |
935 | * This is the blkcg counterpart of ioc_release_fn(). | |
936 | */ | |
937 | static void blkcg_css_offline(struct cgroup_subsys_state *css) | |
938 | { | |
939 | struct blkcg *blkcg = css_to_blkcg(css); | |
940 | ||
941 | spin_lock_irq(&blkcg->lock); | |
942 | ||
943 | while (!hlist_empty(&blkcg->blkg_list)) { | |
944 | struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first, | |
945 | struct blkcg_gq, blkcg_node); | |
946 | struct request_queue *q = blkg->q; | |
947 | ||
948 | if (spin_trylock(q->queue_lock)) { | |
949 | blkg_destroy(blkg); | |
950 | spin_unlock(q->queue_lock); | |
951 | } else { | |
952 | spin_unlock_irq(&blkcg->lock); | |
953 | cpu_relax(); | |
954 | spin_lock_irq(&blkcg->lock); | |
955 | } | |
956 | } | |
957 | ||
958 | spin_unlock_irq(&blkcg->lock); | |
959 | ||
960 | wb_blkcg_offline(blkcg); | |
961 | } | |
962 | ||
963 | static void blkcg_css_free(struct cgroup_subsys_state *css) | |
964 | { | |
965 | struct blkcg *blkcg = css_to_blkcg(css); | |
966 | int i; | |
967 | ||
968 | mutex_lock(&blkcg_pol_mutex); | |
969 | ||
970 | list_del(&blkcg->all_blkcgs_node); | |
971 | ||
972 | for (i = 0; i < BLKCG_MAX_POLS; i++) | |
973 | if (blkcg->cpd[i]) | |
974 | blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]); | |
975 | ||
976 | mutex_unlock(&blkcg_pol_mutex); | |
977 | ||
978 | kfree(blkcg); | |
979 | } | |
980 | ||
981 | static struct cgroup_subsys_state * | |
982 | blkcg_css_alloc(struct cgroup_subsys_state *parent_css) | |
983 | { | |
984 | struct blkcg *blkcg; | |
985 | struct cgroup_subsys_state *ret; | |
986 | int i; | |
987 | ||
988 | mutex_lock(&blkcg_pol_mutex); | |
989 | ||
990 | if (!parent_css) { | |
991 | blkcg = &blkcg_root; | |
992 | } else { | |
993 | blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); | |
994 | if (!blkcg) { | |
995 | ret = ERR_PTR(-ENOMEM); | |
996 | goto free_blkcg; | |
997 | } | |
998 | } | |
999 | ||
1000 | for (i = 0; i < BLKCG_MAX_POLS ; i++) { | |
1001 | struct blkcg_policy *pol = blkcg_policy[i]; | |
1002 | struct blkcg_policy_data *cpd; | |
1003 | ||
1004 | /* | |
1005 | * If the policy hasn't been attached yet, wait for it | |
1006 | * to be attached before doing anything else. Otherwise, | |
1007 | * check if the policy requires any specific per-cgroup | |
1008 | * data: if it does, allocate and initialize it. | |
1009 | */ | |
1010 | if (!pol || !pol->cpd_alloc_fn) | |
1011 | continue; | |
1012 | ||
1013 | cpd = pol->cpd_alloc_fn(GFP_KERNEL); | |
1014 | if (!cpd) { | |
1015 | ret = ERR_PTR(-ENOMEM); | |
1016 | goto free_pd_blkcg; | |
1017 | } | |
1018 | blkcg->cpd[i] = cpd; | |
1019 | cpd->blkcg = blkcg; | |
1020 | cpd->plid = i; | |
1021 | if (pol->cpd_init_fn) | |
1022 | pol->cpd_init_fn(cpd); | |
1023 | } | |
1024 | ||
1025 | spin_lock_init(&blkcg->lock); | |
1026 | INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT | __GFP_NOWARN); | |
1027 | INIT_HLIST_HEAD(&blkcg->blkg_list); | |
1028 | #ifdef CONFIG_CGROUP_WRITEBACK | |
1029 | INIT_LIST_HEAD(&blkcg->cgwb_list); | |
1030 | #endif | |
1031 | list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs); | |
1032 | ||
1033 | mutex_unlock(&blkcg_pol_mutex); | |
1034 | return &blkcg->css; | |
1035 | ||
1036 | free_pd_blkcg: | |
1037 | for (i--; i >= 0; i--) | |
1038 | if (blkcg->cpd[i]) | |
1039 | blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]); | |
1040 | free_blkcg: | |
1041 | kfree(blkcg); | |
1042 | mutex_unlock(&blkcg_pol_mutex); | |
1043 | return ret; | |
1044 | } | |
1045 | ||
1046 | /** | |
1047 | * blkcg_init_queue - initialize blkcg part of request queue | |
1048 | * @q: request_queue to initialize | |
1049 | * | |
1050 | * Called from blk_alloc_queue_node(). Responsible for initializing blkcg | |
1051 | * part of new request_queue @q. | |
1052 | * | |
1053 | * RETURNS: | |
1054 | * 0 on success, -errno on failure. | |
1055 | */ | |
1056 | int blkcg_init_queue(struct request_queue *q) | |
1057 | { | |
1058 | struct blkcg_gq *new_blkg, *blkg; | |
1059 | bool preloaded; | |
1060 | int ret; | |
1061 | ||
1062 | new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL); | |
1063 | if (!new_blkg) | |
1064 | return -ENOMEM; | |
1065 | ||
1066 | preloaded = !radix_tree_preload(GFP_KERNEL); | |
1067 | ||
1068 | /* | |
1069 | * Make sure the root blkg exists and count the existing blkgs. As | |
1070 | * @q is bypassing at this point, blkg_lookup_create() can't be | |
1071 | * used. Open code insertion. | |
1072 | */ | |
1073 | rcu_read_lock(); | |
1074 | spin_lock_irq(q->queue_lock); | |
1075 | blkg = blkg_create(&blkcg_root, q, new_blkg); | |
1076 | spin_unlock_irq(q->queue_lock); | |
1077 | rcu_read_unlock(); | |
1078 | ||
1079 | if (preloaded) | |
1080 | radix_tree_preload_end(); | |
1081 | ||
1082 | if (IS_ERR(blkg)) { | |
1083 | blkg_free(new_blkg); | |
1084 | return PTR_ERR(blkg); | |
1085 | } | |
1086 | ||
1087 | q->root_blkg = blkg; | |
1088 | q->root_rl.blkg = blkg; | |
1089 | ||
1090 | ret = blk_throtl_init(q); | |
1091 | if (ret) { | |
1092 | spin_lock_irq(q->queue_lock); | |
1093 | blkg_destroy_all(q); | |
1094 | spin_unlock_irq(q->queue_lock); | |
1095 | } | |
1096 | return ret; | |
1097 | } | |
1098 | ||
1099 | /** | |
1100 | * blkcg_drain_queue - drain blkcg part of request_queue | |
1101 | * @q: request_queue to drain | |
1102 | * | |
1103 | * Called from blk_drain_queue(). Responsible for draining blkcg part. | |
1104 | */ | |
1105 | void blkcg_drain_queue(struct request_queue *q) | |
1106 | { | |
1107 | lockdep_assert_held(q->queue_lock); | |
1108 | ||
1109 | /* | |
1110 | * @q could be exiting and already have destroyed all blkgs as | |
1111 | * indicated by NULL root_blkg. If so, don't confuse policies. | |
1112 | */ | |
1113 | if (!q->root_blkg) | |
1114 | return; | |
1115 | ||
1116 | blk_throtl_drain(q); | |
1117 | } | |
1118 | ||
1119 | /** | |
1120 | * blkcg_exit_queue - exit and release blkcg part of request_queue | |
1121 | * @q: request_queue being released | |
1122 | * | |
1123 | * Called from blk_release_queue(). Responsible for exiting blkcg part. | |
1124 | */ | |
1125 | void blkcg_exit_queue(struct request_queue *q) | |
1126 | { | |
1127 | spin_lock_irq(q->queue_lock); | |
1128 | blkg_destroy_all(q); | |
1129 | spin_unlock_irq(q->queue_lock); | |
1130 | ||
1131 | blk_throtl_exit(q); | |
1132 | } | |
1133 | ||
1134 | /* | |
1135 | * We cannot support shared io contexts, as we have no mean to support | |
1136 | * two tasks with the same ioc in two different groups without major rework | |
1137 | * of the main cic data structures. For now we allow a task to change | |
1138 | * its cgroup only if it's the only owner of its ioc. | |
1139 | */ | |
1140 | static int blkcg_can_attach(struct cgroup_taskset *tset) | |
1141 | { | |
1142 | struct task_struct *task; | |
1143 | struct cgroup_subsys_state *dst_css; | |
1144 | struct io_context *ioc; | |
1145 | int ret = 0; | |
1146 | ||
1147 | /* task_lock() is needed to avoid races with exit_io_context() */ | |
1148 | cgroup_taskset_for_each(task, dst_css, tset) { | |
1149 | task_lock(task); | |
1150 | ioc = task->io_context; | |
1151 | if (ioc && atomic_read(&ioc->nr_tasks) > 1) | |
1152 | ret = -EINVAL; | |
1153 | task_unlock(task); | |
1154 | if (ret) | |
1155 | break; | |
1156 | } | |
1157 | return ret; | |
1158 | } | |
1159 | ||
1160 | static void blkcg_bind(struct cgroup_subsys_state *root_css) | |
1161 | { | |
1162 | int i; | |
1163 | ||
1164 | mutex_lock(&blkcg_pol_mutex); | |
1165 | ||
1166 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
1167 | struct blkcg_policy *pol = blkcg_policy[i]; | |
1168 | struct blkcg *blkcg; | |
1169 | ||
1170 | if (!pol || !pol->cpd_bind_fn) | |
1171 | continue; | |
1172 | ||
1173 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) | |
1174 | if (blkcg->cpd[pol->plid]) | |
1175 | pol->cpd_bind_fn(blkcg->cpd[pol->plid]); | |
1176 | } | |
1177 | mutex_unlock(&blkcg_pol_mutex); | |
1178 | } | |
1179 | ||
1180 | struct cgroup_subsys io_cgrp_subsys = { | |
1181 | .css_alloc = blkcg_css_alloc, | |
1182 | .css_offline = blkcg_css_offline, | |
1183 | .css_free = blkcg_css_free, | |
1184 | .can_attach = blkcg_can_attach, | |
1185 | .bind = blkcg_bind, | |
1186 | .dfl_cftypes = blkcg_files, | |
1187 | .legacy_cftypes = blkcg_legacy_files, | |
1188 | .legacy_name = "blkio", | |
1189 | #ifdef CONFIG_MEMCG | |
1190 | /* | |
1191 | * This ensures that, if available, memcg is automatically enabled | |
1192 | * together on the default hierarchy so that the owner cgroup can | |
1193 | * be retrieved from writeback pages. | |
1194 | */ | |
1195 | .depends_on = 1 << memory_cgrp_id, | |
1196 | #endif | |
1197 | }; | |
1198 | EXPORT_SYMBOL_GPL(io_cgrp_subsys); | |
1199 | ||
1200 | /** | |
1201 | * blkcg_activate_policy - activate a blkcg policy on a request_queue | |
1202 | * @q: request_queue of interest | |
1203 | * @pol: blkcg policy to activate | |
1204 | * | |
1205 | * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through | |
1206 | * bypass mode to populate its blkgs with policy_data for @pol. | |
1207 | * | |
1208 | * Activation happens with @q bypassed, so nobody would be accessing blkgs | |
1209 | * from IO path. Update of each blkg is protected by both queue and blkcg | |
1210 | * locks so that holding either lock and testing blkcg_policy_enabled() is | |
1211 | * always enough for dereferencing policy data. | |
1212 | * | |
1213 | * The caller is responsible for synchronizing [de]activations and policy | |
1214 | * [un]registerations. Returns 0 on success, -errno on failure. | |
1215 | */ | |
1216 | int blkcg_activate_policy(struct request_queue *q, | |
1217 | const struct blkcg_policy *pol) | |
1218 | { | |
1219 | struct blkg_policy_data *pd_prealloc = NULL; | |
1220 | struct blkcg_gq *blkg; | |
1221 | int ret; | |
1222 | ||
1223 | if (blkcg_policy_enabled(q, pol)) | |
1224 | return 0; | |
1225 | ||
1226 | blk_queue_bypass_start(q); | |
1227 | pd_prealloc: | |
1228 | if (!pd_prealloc) { | |
1229 | pd_prealloc = pol->pd_alloc_fn(GFP_KERNEL, q->node); | |
1230 | if (!pd_prealloc) { | |
1231 | ret = -ENOMEM; | |
1232 | goto out_bypass_end; | |
1233 | } | |
1234 | } | |
1235 | ||
1236 | spin_lock_irq(q->queue_lock); | |
1237 | ||
1238 | list_for_each_entry(blkg, &q->blkg_list, q_node) { | |
1239 | struct blkg_policy_data *pd; | |
1240 | ||
1241 | if (blkg->pd[pol->plid]) | |
1242 | continue; | |
1243 | ||
1244 | pd = pol->pd_alloc_fn(GFP_NOWAIT | __GFP_NOWARN, q->node); | |
1245 | if (!pd) | |
1246 | swap(pd, pd_prealloc); | |
1247 | if (!pd) { | |
1248 | spin_unlock_irq(q->queue_lock); | |
1249 | goto pd_prealloc; | |
1250 | } | |
1251 | ||
1252 | blkg->pd[pol->plid] = pd; | |
1253 | pd->blkg = blkg; | |
1254 | pd->plid = pol->plid; | |
1255 | if (pol->pd_init_fn) | |
1256 | pol->pd_init_fn(pd); | |
1257 | } | |
1258 | ||
1259 | __set_bit(pol->plid, q->blkcg_pols); | |
1260 | ret = 0; | |
1261 | ||
1262 | spin_unlock_irq(q->queue_lock); | |
1263 | out_bypass_end: | |
1264 | blk_queue_bypass_end(q); | |
1265 | if (pd_prealloc) | |
1266 | pol->pd_free_fn(pd_prealloc); | |
1267 | return ret; | |
1268 | } | |
1269 | EXPORT_SYMBOL_GPL(blkcg_activate_policy); | |
1270 | ||
1271 | /** | |
1272 | * blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue | |
1273 | * @q: request_queue of interest | |
1274 | * @pol: blkcg policy to deactivate | |
1275 | * | |
1276 | * Deactivate @pol on @q. Follows the same synchronization rules as | |
1277 | * blkcg_activate_policy(). | |
1278 | */ | |
1279 | void blkcg_deactivate_policy(struct request_queue *q, | |
1280 | const struct blkcg_policy *pol) | |
1281 | { | |
1282 | struct blkcg_gq *blkg; | |
1283 | ||
1284 | if (!blkcg_policy_enabled(q, pol)) | |
1285 | return; | |
1286 | ||
1287 | blk_queue_bypass_start(q); | |
1288 | spin_lock_irq(q->queue_lock); | |
1289 | ||
1290 | __clear_bit(pol->plid, q->blkcg_pols); | |
1291 | ||
1292 | list_for_each_entry(blkg, &q->blkg_list, q_node) { | |
1293 | /* grab blkcg lock too while removing @pd from @blkg */ | |
1294 | spin_lock(&blkg->blkcg->lock); | |
1295 | ||
1296 | if (blkg->pd[pol->plid]) { | |
1297 | if (pol->pd_offline_fn) | |
1298 | pol->pd_offline_fn(blkg->pd[pol->plid]); | |
1299 | pol->pd_free_fn(blkg->pd[pol->plid]); | |
1300 | blkg->pd[pol->plid] = NULL; | |
1301 | } | |
1302 | ||
1303 | spin_unlock(&blkg->blkcg->lock); | |
1304 | } | |
1305 | ||
1306 | spin_unlock_irq(q->queue_lock); | |
1307 | blk_queue_bypass_end(q); | |
1308 | } | |
1309 | EXPORT_SYMBOL_GPL(blkcg_deactivate_policy); | |
1310 | ||
1311 | /** | |
1312 | * blkcg_policy_register - register a blkcg policy | |
1313 | * @pol: blkcg policy to register | |
1314 | * | |
1315 | * Register @pol with blkcg core. Might sleep and @pol may be modified on | |
1316 | * successful registration. Returns 0 on success and -errno on failure. | |
1317 | */ | |
1318 | int blkcg_policy_register(struct blkcg_policy *pol) | |
1319 | { | |
1320 | struct blkcg *blkcg; | |
1321 | int i, ret; | |
1322 | ||
1323 | mutex_lock(&blkcg_pol_register_mutex); | |
1324 | mutex_lock(&blkcg_pol_mutex); | |
1325 | ||
1326 | /* find an empty slot */ | |
1327 | ret = -ENOSPC; | |
1328 | for (i = 0; i < BLKCG_MAX_POLS; i++) | |
1329 | if (!blkcg_policy[i]) | |
1330 | break; | |
1331 | if (i >= BLKCG_MAX_POLS) | |
1332 | goto err_unlock; | |
1333 | ||
1334 | /* register @pol */ | |
1335 | pol->plid = i; | |
1336 | blkcg_policy[pol->plid] = pol; | |
1337 | ||
1338 | /* allocate and install cpd's */ | |
1339 | if (pol->cpd_alloc_fn) { | |
1340 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { | |
1341 | struct blkcg_policy_data *cpd; | |
1342 | ||
1343 | cpd = pol->cpd_alloc_fn(GFP_KERNEL); | |
1344 | if (!cpd) | |
1345 | goto err_free_cpds; | |
1346 | ||
1347 | blkcg->cpd[pol->plid] = cpd; | |
1348 | cpd->blkcg = blkcg; | |
1349 | cpd->plid = pol->plid; | |
1350 | pol->cpd_init_fn(cpd); | |
1351 | } | |
1352 | } | |
1353 | ||
1354 | mutex_unlock(&blkcg_pol_mutex); | |
1355 | ||
1356 | /* everything is in place, add intf files for the new policy */ | |
1357 | if (pol->dfl_cftypes) | |
1358 | WARN_ON(cgroup_add_dfl_cftypes(&io_cgrp_subsys, | |
1359 | pol->dfl_cftypes)); | |
1360 | if (pol->legacy_cftypes) | |
1361 | WARN_ON(cgroup_add_legacy_cftypes(&io_cgrp_subsys, | |
1362 | pol->legacy_cftypes)); | |
1363 | mutex_unlock(&blkcg_pol_register_mutex); | |
1364 | return 0; | |
1365 | ||
1366 | err_free_cpds: | |
1367 | if (pol->cpd_alloc_fn) { | |
1368 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { | |
1369 | if (blkcg->cpd[pol->plid]) { | |
1370 | pol->cpd_free_fn(blkcg->cpd[pol->plid]); | |
1371 | blkcg->cpd[pol->plid] = NULL; | |
1372 | } | |
1373 | } | |
1374 | } | |
1375 | blkcg_policy[pol->plid] = NULL; | |
1376 | err_unlock: | |
1377 | mutex_unlock(&blkcg_pol_mutex); | |
1378 | mutex_unlock(&blkcg_pol_register_mutex); | |
1379 | return ret; | |
1380 | } | |
1381 | EXPORT_SYMBOL_GPL(blkcg_policy_register); | |
1382 | ||
1383 | /** | |
1384 | * blkcg_policy_unregister - unregister a blkcg policy | |
1385 | * @pol: blkcg policy to unregister | |
1386 | * | |
1387 | * Undo blkcg_policy_register(@pol). Might sleep. | |
1388 | */ | |
1389 | void blkcg_policy_unregister(struct blkcg_policy *pol) | |
1390 | { | |
1391 | struct blkcg *blkcg; | |
1392 | ||
1393 | mutex_lock(&blkcg_pol_register_mutex); | |
1394 | ||
1395 | if (WARN_ON(blkcg_policy[pol->plid] != pol)) | |
1396 | goto out_unlock; | |
1397 | ||
1398 | /* kill the intf files first */ | |
1399 | if (pol->dfl_cftypes) | |
1400 | cgroup_rm_cftypes(pol->dfl_cftypes); | |
1401 | if (pol->legacy_cftypes) | |
1402 | cgroup_rm_cftypes(pol->legacy_cftypes); | |
1403 | ||
1404 | /* remove cpds and unregister */ | |
1405 | mutex_lock(&blkcg_pol_mutex); | |
1406 | ||
1407 | if (pol->cpd_alloc_fn) { | |
1408 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { | |
1409 | if (blkcg->cpd[pol->plid]) { | |
1410 | pol->cpd_free_fn(blkcg->cpd[pol->plid]); | |
1411 | blkcg->cpd[pol->plid] = NULL; | |
1412 | } | |
1413 | } | |
1414 | } | |
1415 | blkcg_policy[pol->plid] = NULL; | |
1416 | ||
1417 | mutex_unlock(&blkcg_pol_mutex); | |
1418 | out_unlock: | |
1419 | mutex_unlock(&blkcg_pol_register_mutex); | |
1420 | } | |
1421 | EXPORT_SYMBOL_GPL(blkcg_policy_unregister); |