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3dcf60bc | 1 | // SPDX-License-Identifier: GPL-2.0 |
31e4c28d VG |
2 | /* |
3 | * Common Block IO controller cgroup interface | |
4 | * | |
5 | * Based on ideas and code from CFQ, CFS and BFQ: | |
6 | * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> | |
7 | * | |
8 | * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> | |
9 | * Paolo Valente <paolo.valente@unimore.it> | |
10 | * | |
11 | * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com> | |
12 | * Nauman Rafique <nauman@google.com> | |
e48453c3 AA |
13 | * |
14 | * For policy-specific per-blkcg data: | |
15 | * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it> | |
16 | * Arianna Avanzini <avanzini.arianna@gmail.com> | |
31e4c28d VG |
17 | */ |
18 | #include <linux/ioprio.h> | |
22084190 | 19 | #include <linux/kdev_t.h> |
9d6a986c | 20 | #include <linux/module.h> |
174cd4b1 | 21 | #include <linux/sched/signal.h> |
accee785 | 22 | #include <linux/err.h> |
9195291e | 23 | #include <linux/blkdev.h> |
52ebea74 | 24 | #include <linux/backing-dev.h> |
5a0e3ad6 | 25 | #include <linux/slab.h> |
34d0f179 | 26 | #include <linux/genhd.h> |
72e06c25 | 27 | #include <linux/delay.h> |
9a9e8a26 | 28 | #include <linux/atomic.h> |
36aa9e5f | 29 | #include <linux/ctype.h> |
eea8f41c | 30 | #include <linux/blk-cgroup.h> |
d09d8df3 | 31 | #include <linux/tracehook.h> |
fd112c74 | 32 | #include <linux/psi.h> |
5efd6113 | 33 | #include "blk.h" |
3e252066 | 34 | |
84c124da DS |
35 | #define MAX_KEY_LEN 100 |
36 | ||
838f13bf TH |
37 | /* |
38 | * blkcg_pol_mutex protects blkcg_policy[] and policy [de]activation. | |
39 | * blkcg_pol_register_mutex nests outside of it and synchronizes entire | |
40 | * policy [un]register operations including cgroup file additions / | |
41 | * removals. Putting cgroup file registration outside blkcg_pol_mutex | |
42 | * allows grabbing it from cgroup callbacks. | |
43 | */ | |
44 | static DEFINE_MUTEX(blkcg_pol_register_mutex); | |
bc0d6501 | 45 | static DEFINE_MUTEX(blkcg_pol_mutex); |
923adde1 | 46 | |
e48453c3 | 47 | struct blkcg blkcg_root; |
3c798398 | 48 | EXPORT_SYMBOL_GPL(blkcg_root); |
9d6a986c | 49 | |
496d5e75 | 50 | struct cgroup_subsys_state * const blkcg_root_css = &blkcg_root.css; |
9b0eb69b | 51 | EXPORT_SYMBOL_GPL(blkcg_root_css); |
496d5e75 | 52 | |
3c798398 | 53 | static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS]; |
035d10b2 | 54 | |
7876f930 TH |
55 | static LIST_HEAD(all_blkcgs); /* protected by blkcg_pol_mutex */ |
56 | ||
07b0fdec | 57 | bool blkcg_debug_stats = false; |
d3f77dfd | 58 | static struct workqueue_struct *blkcg_punt_bio_wq; |
903d23f0 | 59 | |
a2b1693b | 60 | static bool blkcg_policy_enabled(struct request_queue *q, |
3c798398 | 61 | const struct blkcg_policy *pol) |
a2b1693b TH |
62 | { |
63 | return pol && test_bit(pol->plid, q->blkcg_pols); | |
64 | } | |
65 | ||
0381411e TH |
66 | /** |
67 | * blkg_free - free a blkg | |
68 | * @blkg: blkg to free | |
69 | * | |
70 | * Free @blkg which may be partially allocated. | |
71 | */ | |
3c798398 | 72 | static void blkg_free(struct blkcg_gq *blkg) |
0381411e | 73 | { |
e8989fae | 74 | int i; |
549d3aa8 TH |
75 | |
76 | if (!blkg) | |
77 | return; | |
78 | ||
db613670 | 79 | for (i = 0; i < BLKCG_MAX_POLS; i++) |
001bea73 TH |
80 | if (blkg->pd[i]) |
81 | blkcg_policy[i]->pd_free_fn(blkg->pd[i]); | |
e8989fae | 82 | |
f7331648 | 83 | free_percpu(blkg->iostat_cpu); |
ef069b97 | 84 | percpu_ref_exit(&blkg->refcnt); |
549d3aa8 | 85 | kfree(blkg); |
0381411e TH |
86 | } |
87 | ||
7fcf2b03 DZ |
88 | static void __blkg_release(struct rcu_head *rcu) |
89 | { | |
90 | struct blkcg_gq *blkg = container_of(rcu, struct blkcg_gq, rcu_head); | |
91 | ||
d3f77dfd TH |
92 | WARN_ON(!bio_list_empty(&blkg->async_bios)); |
93 | ||
7fcf2b03 DZ |
94 | /* release the blkcg and parent blkg refs this blkg has been holding */ |
95 | css_put(&blkg->blkcg->css); | |
96 | if (blkg->parent) | |
97 | blkg_put(blkg->parent); | |
98 | ||
99 | wb_congested_put(blkg->wb_congested); | |
100 | ||
101 | blkg_free(blkg); | |
102 | } | |
103 | ||
104 | /* | |
105 | * A group is RCU protected, but having an rcu lock does not mean that one | |
106 | * can access all the fields of blkg and assume these are valid. For | |
107 | * example, don't try to follow throtl_data and request queue links. | |
108 | * | |
109 | * Having a reference to blkg under an rcu allows accesses to only values | |
110 | * local to groups like group stats and group rate limits. | |
111 | */ | |
112 | static void blkg_release(struct percpu_ref *ref) | |
113 | { | |
114 | struct blkcg_gq *blkg = container_of(ref, struct blkcg_gq, refcnt); | |
115 | ||
116 | call_rcu(&blkg->rcu_head, __blkg_release); | |
117 | } | |
118 | ||
d3f77dfd TH |
119 | static void blkg_async_bio_workfn(struct work_struct *work) |
120 | { | |
121 | struct blkcg_gq *blkg = container_of(work, struct blkcg_gq, | |
122 | async_bio_work); | |
123 | struct bio_list bios = BIO_EMPTY_LIST; | |
124 | struct bio *bio; | |
125 | ||
126 | /* as long as there are pending bios, @blkg can't go away */ | |
127 | spin_lock_bh(&blkg->async_bio_lock); | |
128 | bio_list_merge(&bios, &blkg->async_bios); | |
129 | bio_list_init(&blkg->async_bios); | |
130 | spin_unlock_bh(&blkg->async_bio_lock); | |
131 | ||
132 | while ((bio = bio_list_pop(&bios))) | |
133 | submit_bio(bio); | |
134 | } | |
135 | ||
0381411e TH |
136 | /** |
137 | * blkg_alloc - allocate a blkg | |
138 | * @blkcg: block cgroup the new blkg is associated with | |
139 | * @q: request_queue the new blkg is associated with | |
15974993 | 140 | * @gfp_mask: allocation mask to use |
0381411e | 141 | * |
e8989fae | 142 | * Allocate a new blkg assocating @blkcg and @q. |
0381411e | 143 | */ |
15974993 TH |
144 | static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, |
145 | gfp_t gfp_mask) | |
0381411e | 146 | { |
3c798398 | 147 | struct blkcg_gq *blkg; |
f7331648 | 148 | int i, cpu; |
0381411e TH |
149 | |
150 | /* alloc and init base part */ | |
15974993 | 151 | blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node); |
0381411e TH |
152 | if (!blkg) |
153 | return NULL; | |
154 | ||
ef069b97 TH |
155 | if (percpu_ref_init(&blkg->refcnt, blkg_release, 0, gfp_mask)) |
156 | goto err_free; | |
157 | ||
f7331648 TH |
158 | blkg->iostat_cpu = alloc_percpu_gfp(struct blkg_iostat_set, gfp_mask); |
159 | if (!blkg->iostat_cpu) | |
77ea7338 TH |
160 | goto err_free; |
161 | ||
c875f4d0 | 162 | blkg->q = q; |
e8989fae | 163 | INIT_LIST_HEAD(&blkg->q_node); |
d3f77dfd TH |
164 | spin_lock_init(&blkg->async_bio_lock); |
165 | bio_list_init(&blkg->async_bios); | |
166 | INIT_WORK(&blkg->async_bio_work, blkg_async_bio_workfn); | |
0381411e | 167 | blkg->blkcg = blkcg; |
0381411e | 168 | |
f7331648 TH |
169 | u64_stats_init(&blkg->iostat.sync); |
170 | for_each_possible_cpu(cpu) | |
171 | u64_stats_init(&per_cpu_ptr(blkg->iostat_cpu, cpu)->sync); | |
172 | ||
8bd435b3 | 173 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
3c798398 | 174 | struct blkcg_policy *pol = blkcg_policy[i]; |
e8989fae | 175 | struct blkg_policy_data *pd; |
0381411e | 176 | |
a2b1693b | 177 | if (!blkcg_policy_enabled(q, pol)) |
e8989fae TH |
178 | continue; |
179 | ||
180 | /* alloc per-policy data and attach it to blkg */ | |
cf09a8ee | 181 | pd = pol->pd_alloc_fn(gfp_mask, q, blkcg); |
a051661c TH |
182 | if (!pd) |
183 | goto err_free; | |
549d3aa8 | 184 | |
e8989fae TH |
185 | blkg->pd[i] = pd; |
186 | pd->blkg = blkg; | |
b276a876 | 187 | pd->plid = i; |
e8989fae TH |
188 | } |
189 | ||
0381411e | 190 | return blkg; |
a051661c TH |
191 | |
192 | err_free: | |
193 | blkg_free(blkg); | |
194 | return NULL; | |
0381411e TH |
195 | } |
196 | ||
24f29046 TH |
197 | struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg, |
198 | struct request_queue *q, bool update_hint) | |
80fd9979 | 199 | { |
3c798398 | 200 | struct blkcg_gq *blkg; |
80fd9979 | 201 | |
a637120e | 202 | /* |
86cde6b6 TH |
203 | * Hint didn't match. Look up from the radix tree. Note that the |
204 | * hint can only be updated under queue_lock as otherwise @blkg | |
205 | * could have already been removed from blkg_tree. The caller is | |
206 | * responsible for grabbing queue_lock if @update_hint. | |
a637120e TH |
207 | */ |
208 | blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); | |
86cde6b6 TH |
209 | if (blkg && blkg->q == q) { |
210 | if (update_hint) { | |
0d945c1f | 211 | lockdep_assert_held(&q->queue_lock); |
86cde6b6 TH |
212 | rcu_assign_pointer(blkcg->blkg_hint, blkg); |
213 | } | |
a637120e | 214 | return blkg; |
86cde6b6 | 215 | } |
a637120e | 216 | |
80fd9979 TH |
217 | return NULL; |
218 | } | |
ae118896 | 219 | EXPORT_SYMBOL_GPL(blkg_lookup_slowpath); |
80fd9979 | 220 | |
15974993 | 221 | /* |
d708f0d5 JA |
222 | * If @new_blkg is %NULL, this function tries to allocate a new one as |
223 | * necessary using %GFP_NOWAIT. @new_blkg is always consumed on return. | |
15974993 | 224 | */ |
86cde6b6 | 225 | static struct blkcg_gq *blkg_create(struct blkcg *blkcg, |
d708f0d5 JA |
226 | struct request_queue *q, |
227 | struct blkcg_gq *new_blkg) | |
5624a4e4 | 228 | { |
d708f0d5 | 229 | struct blkcg_gq *blkg; |
ce7acfea | 230 | struct bdi_writeback_congested *wb_congested; |
f427d909 | 231 | int i, ret; |
5624a4e4 | 232 | |
cd1604fa | 233 | WARN_ON_ONCE(!rcu_read_lock_held()); |
0d945c1f | 234 | lockdep_assert_held(&q->queue_lock); |
cd1604fa | 235 | |
0273ac34 DZ |
236 | /* request_queue is dying, do not create/recreate a blkg */ |
237 | if (blk_queue_dying(q)) { | |
238 | ret = -ENODEV; | |
239 | goto err_free_blkg; | |
240 | } | |
241 | ||
7ee9c562 | 242 | /* blkg holds a reference to blkcg */ |
ec903c0c | 243 | if (!css_tryget_online(&blkcg->css)) { |
20386ce0 | 244 | ret = -ENODEV; |
93e6d5d8 | 245 | goto err_free_blkg; |
15974993 | 246 | } |
cd1604fa | 247 | |
dc3b17cc | 248 | wb_congested = wb_congested_get_create(q->backing_dev_info, |
d708f0d5 JA |
249 | blkcg->css.id, |
250 | GFP_NOWAIT | __GFP_NOWARN); | |
251 | if (!wb_congested) { | |
ce7acfea | 252 | ret = -ENOMEM; |
d708f0d5 | 253 | goto err_put_css; |
ce7acfea TH |
254 | } |
255 | ||
d708f0d5 JA |
256 | /* allocate */ |
257 | if (!new_blkg) { | |
258 | new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT | __GFP_NOWARN); | |
259 | if (unlikely(!new_blkg)) { | |
260 | ret = -ENOMEM; | |
261 | goto err_put_congested; | |
15974993 TH |
262 | } |
263 | } | |
d708f0d5 JA |
264 | blkg = new_blkg; |
265 | blkg->wb_congested = wb_congested; | |
cd1604fa | 266 | |
db613670 | 267 | /* link parent */ |
3c547865 TH |
268 | if (blkcg_parent(blkcg)) { |
269 | blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false); | |
270 | if (WARN_ON_ONCE(!blkg->parent)) { | |
20386ce0 | 271 | ret = -ENODEV; |
d708f0d5 | 272 | goto err_put_congested; |
3c547865 TH |
273 | } |
274 | blkg_get(blkg->parent); | |
275 | } | |
276 | ||
db613670 TH |
277 | /* invoke per-policy init */ |
278 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
279 | struct blkcg_policy *pol = blkcg_policy[i]; | |
280 | ||
281 | if (blkg->pd[i] && pol->pd_init_fn) | |
a9520cd6 | 282 | pol->pd_init_fn(blkg->pd[i]); |
db613670 TH |
283 | } |
284 | ||
285 | /* insert */ | |
cd1604fa | 286 | spin_lock(&blkcg->lock); |
a637120e TH |
287 | ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg); |
288 | if (likely(!ret)) { | |
289 | hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); | |
290 | list_add(&blkg->q_node, &q->blkg_list); | |
f427d909 TH |
291 | |
292 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
293 | struct blkcg_policy *pol = blkcg_policy[i]; | |
294 | ||
295 | if (blkg->pd[i] && pol->pd_online_fn) | |
a9520cd6 | 296 | pol->pd_online_fn(blkg->pd[i]); |
f427d909 | 297 | } |
a637120e | 298 | } |
f427d909 | 299 | blkg->online = true; |
cd1604fa | 300 | spin_unlock(&blkcg->lock); |
496fb780 | 301 | |
ec13b1d6 | 302 | if (!ret) |
a637120e | 303 | return blkg; |
15974993 | 304 | |
3c547865 TH |
305 | /* @blkg failed fully initialized, use the usual release path */ |
306 | blkg_put(blkg); | |
307 | return ERR_PTR(ret); | |
308 | ||
d708f0d5 JA |
309 | err_put_congested: |
310 | wb_congested_put(wb_congested); | |
311 | err_put_css: | |
496fb780 | 312 | css_put(&blkcg->css); |
93e6d5d8 | 313 | err_free_blkg: |
d708f0d5 | 314 | blkg_free(new_blkg); |
93e6d5d8 | 315 | return ERR_PTR(ret); |
31e4c28d | 316 | } |
3c96cb32 | 317 | |
86cde6b6 | 318 | /** |
b978962a | 319 | * __blkg_lookup_create - lookup blkg, try to create one if not there |
86cde6b6 TH |
320 | * @blkcg: blkcg of interest |
321 | * @q: request_queue of interest | |
322 | * | |
323 | * Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to | |
3c547865 TH |
324 | * create one. blkg creation is performed recursively from blkcg_root such |
325 | * that all non-root blkg's have access to the parent blkg. This function | |
326 | * should be called under RCU read lock and @q->queue_lock. | |
86cde6b6 | 327 | * |
beea9da0 DZ |
328 | * Returns the blkg or the closest blkg if blkg_create() fails as it walks |
329 | * down from root. | |
86cde6b6 | 330 | */ |
b978962a DZ |
331 | struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, |
332 | struct request_queue *q) | |
3c96cb32 | 333 | { |
86cde6b6 TH |
334 | struct blkcg_gq *blkg; |
335 | ||
336 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
0d945c1f | 337 | lockdep_assert_held(&q->queue_lock); |
86cde6b6 | 338 | |
86cde6b6 TH |
339 | blkg = __blkg_lookup(blkcg, q, true); |
340 | if (blkg) | |
341 | return blkg; | |
342 | ||
3c547865 TH |
343 | /* |
344 | * Create blkgs walking down from blkcg_root to @blkcg, so that all | |
beea9da0 DZ |
345 | * non-root blkgs have access to their parents. Returns the closest |
346 | * blkg to the intended blkg should blkg_create() fail. | |
3c547865 TH |
347 | */ |
348 | while (true) { | |
349 | struct blkcg *pos = blkcg; | |
350 | struct blkcg *parent = blkcg_parent(blkcg); | |
beea9da0 DZ |
351 | struct blkcg_gq *ret_blkg = q->root_blkg; |
352 | ||
353 | while (parent) { | |
354 | blkg = __blkg_lookup(parent, q, false); | |
355 | if (blkg) { | |
356 | /* remember closest blkg */ | |
357 | ret_blkg = blkg; | |
358 | break; | |
359 | } | |
3c547865 TH |
360 | pos = parent; |
361 | parent = blkcg_parent(parent); | |
362 | } | |
363 | ||
d708f0d5 | 364 | blkg = blkg_create(pos, q, NULL); |
beea9da0 DZ |
365 | if (IS_ERR(blkg)) |
366 | return ret_blkg; | |
367 | if (pos == blkcg) | |
3c547865 TH |
368 | return blkg; |
369 | } | |
3c96cb32 | 370 | } |
31e4c28d | 371 | |
b978962a DZ |
372 | /** |
373 | * blkg_lookup_create - find or create a blkg | |
374 | * @blkcg: target block cgroup | |
375 | * @q: target request_queue | |
376 | * | |
377 | * This looks up or creates the blkg representing the unique pair | |
378 | * of the blkcg and the request_queue. | |
379 | */ | |
380 | struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, | |
381 | struct request_queue *q) | |
382 | { | |
383 | struct blkcg_gq *blkg = blkg_lookup(blkcg, q); | |
384 | ||
385 | if (unlikely(!blkg)) { | |
3a762de5 ML |
386 | unsigned long flags; |
387 | ||
388 | spin_lock_irqsave(&q->queue_lock, flags); | |
b978962a | 389 | blkg = __blkg_lookup_create(blkcg, q); |
3a762de5 | 390 | spin_unlock_irqrestore(&q->queue_lock, flags); |
b978962a DZ |
391 | } |
392 | ||
393 | return blkg; | |
394 | } | |
395 | ||
3c798398 | 396 | static void blkg_destroy(struct blkcg_gq *blkg) |
03aa264a | 397 | { |
3c798398 | 398 | struct blkcg *blkcg = blkg->blkcg; |
6b065462 | 399 | int i; |
03aa264a | 400 | |
0d945c1f | 401 | lockdep_assert_held(&blkg->q->queue_lock); |
9f13ef67 | 402 | lockdep_assert_held(&blkcg->lock); |
03aa264a TH |
403 | |
404 | /* Something wrong if we are trying to remove same group twice */ | |
e8989fae | 405 | WARN_ON_ONCE(list_empty(&blkg->q_node)); |
9f13ef67 | 406 | WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node)); |
a637120e | 407 | |
6b065462 DZF |
408 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
409 | struct blkcg_policy *pol = blkcg_policy[i]; | |
410 | ||
411 | if (blkg->pd[i] && pol->pd_offline_fn) | |
412 | pol->pd_offline_fn(blkg->pd[i]); | |
413 | } | |
414 | ||
f427d909 TH |
415 | blkg->online = false; |
416 | ||
a637120e | 417 | radix_tree_delete(&blkcg->blkg_tree, blkg->q->id); |
e8989fae | 418 | list_del_init(&blkg->q_node); |
9f13ef67 | 419 | hlist_del_init_rcu(&blkg->blkcg_node); |
03aa264a | 420 | |
a637120e TH |
421 | /* |
422 | * Both setting lookup hint to and clearing it from @blkg are done | |
423 | * under queue_lock. If it's not pointing to @blkg now, it never | |
424 | * will. Hint assignment itself can race safely. | |
425 | */ | |
ec6c676a | 426 | if (rcu_access_pointer(blkcg->blkg_hint) == blkg) |
a637120e TH |
427 | rcu_assign_pointer(blkcg->blkg_hint, NULL); |
428 | ||
03aa264a TH |
429 | /* |
430 | * Put the reference taken at the time of creation so that when all | |
431 | * queues are gone, group can be destroyed. | |
432 | */ | |
7fcf2b03 | 433 | percpu_ref_kill(&blkg->refcnt); |
03aa264a TH |
434 | } |
435 | ||
9f13ef67 TH |
436 | /** |
437 | * blkg_destroy_all - destroy all blkgs associated with a request_queue | |
438 | * @q: request_queue of interest | |
9f13ef67 | 439 | * |
3c96cb32 | 440 | * Destroy all blkgs associated with @q. |
9f13ef67 | 441 | */ |
3c96cb32 | 442 | static void blkg_destroy_all(struct request_queue *q) |
72e06c25 | 443 | { |
3c798398 | 444 | struct blkcg_gq *blkg, *n; |
72e06c25 | 445 | |
0d945c1f | 446 | spin_lock_irq(&q->queue_lock); |
9f13ef67 | 447 | list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { |
3c798398 | 448 | struct blkcg *blkcg = blkg->blkcg; |
72e06c25 | 449 | |
9f13ef67 TH |
450 | spin_lock(&blkcg->lock); |
451 | blkg_destroy(blkg); | |
452 | spin_unlock(&blkcg->lock); | |
72e06c25 | 453 | } |
6fe810bd TH |
454 | |
455 | q->root_blkg = NULL; | |
0d945c1f | 456 | spin_unlock_irq(&q->queue_lock); |
72e06c25 TH |
457 | } |
458 | ||
182446d0 TH |
459 | static int blkcg_reset_stats(struct cgroup_subsys_state *css, |
460 | struct cftype *cftype, u64 val) | |
303a3acb | 461 | { |
182446d0 | 462 | struct blkcg *blkcg = css_to_blkcg(css); |
3c798398 | 463 | struct blkcg_gq *blkg; |
f7331648 | 464 | int i, cpu; |
303a3acb | 465 | |
838f13bf | 466 | mutex_lock(&blkcg_pol_mutex); |
303a3acb | 467 | spin_lock_irq(&blkcg->lock); |
997a026c TH |
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 | */ | |
b67bfe0d | 474 | hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { |
f7331648 TH |
475 | for_each_possible_cpu(cpu) { |
476 | struct blkg_iostat_set *bis = | |
477 | per_cpu_ptr(blkg->iostat_cpu, cpu); | |
478 | memset(bis, 0, sizeof(*bis)); | |
479 | } | |
480 | memset(&blkg->iostat, 0, sizeof(blkg->iostat)); | |
77ea7338 | 481 | |
8bd435b3 | 482 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
3c798398 | 483 | struct blkcg_policy *pol = blkcg_policy[i]; |
549d3aa8 | 484 | |
a9520cd6 TH |
485 | if (blkg->pd[i] && pol->pd_reset_stats_fn) |
486 | pol->pd_reset_stats_fn(blkg->pd[i]); | |
bc0d6501 | 487 | } |
303a3acb | 488 | } |
f0bdc8cd | 489 | |
303a3acb | 490 | spin_unlock_irq(&blkcg->lock); |
bc0d6501 | 491 | mutex_unlock(&blkcg_pol_mutex); |
303a3acb DS |
492 | return 0; |
493 | } | |
494 | ||
dd165eb3 | 495 | const char *blkg_dev_name(struct blkcg_gq *blkg) |
303a3acb | 496 | { |
d3d32e69 | 497 | /* some drivers (floppy) instantiate a queue w/o disk registered */ |
dc3b17cc | 498 | if (blkg->q->backing_dev_info->dev) |
d51cfc53 | 499 | return bdi_dev_name(blkg->q->backing_dev_info); |
d3d32e69 | 500 | return NULL; |
303a3acb DS |
501 | } |
502 | ||
d3d32e69 TH |
503 | /** |
504 | * blkcg_print_blkgs - helper for printing per-blkg data | |
505 | * @sf: seq_file to print to | |
506 | * @blkcg: blkcg of interest | |
507 | * @prfill: fill function to print out a blkg | |
508 | * @pol: policy in question | |
509 | * @data: data to be passed to @prfill | |
510 | * @show_total: to print out sum of prfill return values or not | |
511 | * | |
512 | * This function invokes @prfill on each blkg of @blkcg if pd for the | |
513 | * policy specified by @pol exists. @prfill is invoked with @sf, the | |
810ecfa7 TH |
514 | * policy data and @data and the matching queue lock held. If @show_total |
515 | * is %true, the sum of the return values from @prfill is printed with | |
516 | * "Total" label at the end. | |
d3d32e69 TH |
517 | * |
518 | * This is to be used to construct print functions for | |
519 | * cftype->read_seq_string method. | |
520 | */ | |
3c798398 | 521 | void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg, |
f95a04af TH |
522 | u64 (*prfill)(struct seq_file *, |
523 | struct blkg_policy_data *, int), | |
3c798398 | 524 | const struct blkcg_policy *pol, int data, |
ec399347 | 525 | bool show_total) |
5624a4e4 | 526 | { |
3c798398 | 527 | struct blkcg_gq *blkg; |
d3d32e69 | 528 | u64 total = 0; |
5624a4e4 | 529 | |
810ecfa7 | 530 | rcu_read_lock(); |
ee89f812 | 531 | hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { |
0d945c1f | 532 | spin_lock_irq(&blkg->q->queue_lock); |
a2b1693b | 533 | if (blkcg_policy_enabled(blkg->q, pol)) |
f95a04af | 534 | total += prfill(sf, blkg->pd[pol->plid], data); |
0d945c1f | 535 | spin_unlock_irq(&blkg->q->queue_lock); |
810ecfa7 TH |
536 | } |
537 | rcu_read_unlock(); | |
d3d32e69 TH |
538 | |
539 | if (show_total) | |
540 | seq_printf(sf, "Total %llu\n", (unsigned long long)total); | |
541 | } | |
829fdb50 | 542 | EXPORT_SYMBOL_GPL(blkcg_print_blkgs); |
d3d32e69 TH |
543 | |
544 | /** | |
545 | * __blkg_prfill_u64 - prfill helper for a single u64 value | |
546 | * @sf: seq_file to print to | |
f95a04af | 547 | * @pd: policy private data of interest |
d3d32e69 TH |
548 | * @v: value to print |
549 | * | |
f95a04af | 550 | * Print @v to @sf for the device assocaited with @pd. |
d3d32e69 | 551 | */ |
f95a04af | 552 | u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v) |
d3d32e69 | 553 | { |
f95a04af | 554 | const char *dname = blkg_dev_name(pd->blkg); |
d3d32e69 TH |
555 | |
556 | if (!dname) | |
557 | return 0; | |
558 | ||
559 | seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v); | |
560 | return v; | |
561 | } | |
829fdb50 | 562 | EXPORT_SYMBOL_GPL(__blkg_prfill_u64); |
d3d32e69 | 563 | |
457e490f TE |
564 | /* Performs queue bypass and policy enabled checks then looks up blkg. */ |
565 | static struct blkcg_gq *blkg_lookup_check(struct blkcg *blkcg, | |
566 | const struct blkcg_policy *pol, | |
567 | struct request_queue *q) | |
568 | { | |
569 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
0d945c1f | 570 | lockdep_assert_held(&q->queue_lock); |
457e490f TE |
571 | |
572 | if (!blkcg_policy_enabled(q, pol)) | |
573 | return ERR_PTR(-EOPNOTSUPP); | |
457e490f TE |
574 | return __blkg_lookup(blkcg, q, true /* update_hint */); |
575 | } | |
576 | ||
015d254c TH |
577 | /** |
578 | * blkg_conf_prep - parse and prepare for per-blkg config update | |
579 | * @inputp: input string pointer | |
580 | * | |
581 | * Parse the device node prefix part, MAJ:MIN, of per-blkg config update | |
582 | * from @input and get and return the matching gendisk. *@inputp is | |
583 | * updated to point past the device node prefix. Returns an ERR_PTR() | |
584 | * value on error. | |
585 | * | |
586 | * Use this function iff blkg_conf_prep() can't be used for some reason. | |
587 | */ | |
588 | struct gendisk *blkcg_conf_get_disk(char **inputp) | |
589 | { | |
590 | char *input = *inputp; | |
591 | unsigned int major, minor; | |
592 | struct gendisk *disk; | |
593 | int key_len, part; | |
594 | ||
595 | if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2) | |
596 | return ERR_PTR(-EINVAL); | |
597 | ||
598 | input += key_len; | |
599 | if (!isspace(*input)) | |
600 | return ERR_PTR(-EINVAL); | |
601 | input = skip_spaces(input); | |
602 | ||
603 | disk = get_gendisk(MKDEV(major, minor), &part); | |
604 | if (!disk) | |
605 | return ERR_PTR(-ENODEV); | |
606 | if (part) { | |
607 | put_disk_and_module(disk); | |
608 | return ERR_PTR(-ENODEV); | |
609 | } | |
610 | ||
611 | *inputp = input; | |
612 | return disk; | |
613 | } | |
614 | ||
3a8b31d3 TH |
615 | /** |
616 | * blkg_conf_prep - parse and prepare for per-blkg config update | |
617 | * @blkcg: target block cgroup | |
da8b0662 | 618 | * @pol: target policy |
3a8b31d3 TH |
619 | * @input: input string |
620 | * @ctx: blkg_conf_ctx to be filled | |
621 | * | |
622 | * Parse per-blkg config update from @input and initialize @ctx with the | |
36aa9e5f TH |
623 | * result. @ctx->blkg points to the blkg to be updated and @ctx->body the |
624 | * part of @input following MAJ:MIN. This function returns with RCU read | |
625 | * lock and queue lock held and must be paired with blkg_conf_finish(). | |
3a8b31d3 | 626 | */ |
3c798398 | 627 | int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, |
36aa9e5f | 628 | char *input, struct blkg_conf_ctx *ctx) |
0d945c1f | 629 | __acquires(rcu) __acquires(&disk->queue->queue_lock) |
34d0f179 | 630 | { |
3a8b31d3 | 631 | struct gendisk *disk; |
457e490f | 632 | struct request_queue *q; |
3c798398 | 633 | struct blkcg_gq *blkg; |
015d254c | 634 | int ret; |
36aa9e5f | 635 | |
015d254c TH |
636 | disk = blkcg_conf_get_disk(&input); |
637 | if (IS_ERR(disk)) | |
638 | return PTR_ERR(disk); | |
e56da7e2 | 639 | |
457e490f | 640 | q = disk->queue; |
da8b0662 | 641 | |
457e490f | 642 | rcu_read_lock(); |
0d945c1f | 643 | spin_lock_irq(&q->queue_lock); |
e56da7e2 | 644 | |
457e490f | 645 | blkg = blkg_lookup_check(blkcg, pol, q); |
4bfd482e TH |
646 | if (IS_ERR(blkg)) { |
647 | ret = PTR_ERR(blkg); | |
457e490f TE |
648 | goto fail_unlock; |
649 | } | |
650 | ||
651 | if (blkg) | |
652 | goto success; | |
653 | ||
654 | /* | |
655 | * Create blkgs walking down from blkcg_root to @blkcg, so that all | |
656 | * non-root blkgs have access to their parents. | |
657 | */ | |
658 | while (true) { | |
659 | struct blkcg *pos = blkcg; | |
660 | struct blkcg *parent; | |
661 | struct blkcg_gq *new_blkg; | |
662 | ||
663 | parent = blkcg_parent(blkcg); | |
664 | while (parent && !__blkg_lookup(parent, q, false)) { | |
665 | pos = parent; | |
666 | parent = blkcg_parent(parent); | |
667 | } | |
668 | ||
669 | /* Drop locks to do new blkg allocation with GFP_KERNEL. */ | |
0d945c1f | 670 | spin_unlock_irq(&q->queue_lock); |
3a8b31d3 | 671 | rcu_read_unlock(); |
457e490f TE |
672 | |
673 | new_blkg = blkg_alloc(pos, q, GFP_KERNEL); | |
674 | if (unlikely(!new_blkg)) { | |
675 | ret = -ENOMEM; | |
676 | goto fail; | |
7702e8f4 | 677 | } |
3a8b31d3 | 678 | |
457e490f | 679 | rcu_read_lock(); |
0d945c1f | 680 | spin_lock_irq(&q->queue_lock); |
457e490f TE |
681 | |
682 | blkg = blkg_lookup_check(pos, pol, q); | |
683 | if (IS_ERR(blkg)) { | |
684 | ret = PTR_ERR(blkg); | |
685 | goto fail_unlock; | |
686 | } | |
687 | ||
688 | if (blkg) { | |
689 | blkg_free(new_blkg); | |
690 | } else { | |
691 | blkg = blkg_create(pos, q, new_blkg); | |
98d669b4 | 692 | if (IS_ERR(blkg)) { |
457e490f TE |
693 | ret = PTR_ERR(blkg); |
694 | goto fail_unlock; | |
695 | } | |
696 | } | |
697 | ||
698 | if (pos == blkcg) | |
699 | goto success; | |
700 | } | |
701 | success: | |
3a8b31d3 TH |
702 | ctx->disk = disk; |
703 | ctx->blkg = blkg; | |
015d254c | 704 | ctx->body = input; |
726fa694 | 705 | return 0; |
457e490f TE |
706 | |
707 | fail_unlock: | |
0d945c1f | 708 | spin_unlock_irq(&q->queue_lock); |
457e490f TE |
709 | rcu_read_unlock(); |
710 | fail: | |
9df6c299 | 711 | put_disk_and_module(disk); |
457e490f TE |
712 | /* |
713 | * If queue was bypassing, we should retry. Do so after a | |
714 | * short msleep(). It isn't strictly necessary but queue | |
715 | * can be bypassing for some time and it's always nice to | |
716 | * avoid busy looping. | |
717 | */ | |
718 | if (ret == -EBUSY) { | |
719 | msleep(10); | |
720 | ret = restart_syscall(); | |
721 | } | |
722 | return ret; | |
34d0f179 | 723 | } |
89f3b6d6 | 724 | EXPORT_SYMBOL_GPL(blkg_conf_prep); |
34d0f179 | 725 | |
3a8b31d3 TH |
726 | /** |
727 | * blkg_conf_finish - finish up per-blkg config update | |
728 | * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep() | |
729 | * | |
730 | * Finish up after per-blkg config update. This function must be paired | |
731 | * with blkg_conf_prep(). | |
732 | */ | |
829fdb50 | 733 | void blkg_conf_finish(struct blkg_conf_ctx *ctx) |
0d945c1f | 734 | __releases(&ctx->disk->queue->queue_lock) __releases(rcu) |
34d0f179 | 735 | { |
0d945c1f | 736 | spin_unlock_irq(&ctx->disk->queue->queue_lock); |
3a8b31d3 | 737 | rcu_read_unlock(); |
9df6c299 | 738 | put_disk_and_module(ctx->disk); |
34d0f179 | 739 | } |
89f3b6d6 | 740 | EXPORT_SYMBOL_GPL(blkg_conf_finish); |
34d0f179 | 741 | |
2ee867dc TH |
742 | static int blkcg_print_stat(struct seq_file *sf, void *v) |
743 | { | |
744 | struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); | |
745 | struct blkcg_gq *blkg; | |
746 | ||
f7331648 | 747 | cgroup_rstat_flush(blkcg->css.cgroup); |
2ee867dc TH |
748 | rcu_read_lock(); |
749 | ||
750 | hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { | |
f7331648 | 751 | struct blkg_iostat_set *bis = &blkg->iostat; |
2ee867dc | 752 | const char *dname; |
903d23f0 | 753 | char *buf; |
636620b6 | 754 | u64 rbytes, wbytes, rios, wios, dbytes, dios; |
903d23f0 JB |
755 | size_t size = seq_get_buf(sf, &buf), off = 0; |
756 | int i; | |
757 | bool has_stats = false; | |
f7331648 | 758 | unsigned seq; |
2ee867dc | 759 | |
b0814361 TH |
760 | spin_lock_irq(&blkg->q->queue_lock); |
761 | ||
762 | if (!blkg->online) | |
763 | goto skip; | |
764 | ||
2ee867dc TH |
765 | dname = blkg_dev_name(blkg); |
766 | if (!dname) | |
b0814361 | 767 | goto skip; |
2ee867dc | 768 | |
903d23f0 JB |
769 | /* |
770 | * Hooray string manipulation, count is the size written NOT | |
771 | * INCLUDING THE \0, so size is now count+1 less than what we | |
772 | * had before, but we want to start writing the next bit from | |
773 | * the \0 so we only add count to buf. | |
774 | */ | |
775 | off += scnprintf(buf+off, size-off, "%s ", dname); | |
776 | ||
f7331648 TH |
777 | do { |
778 | seq = u64_stats_fetch_begin(&bis->sync); | |
2ee867dc | 779 | |
f7331648 TH |
780 | rbytes = bis->cur.bytes[BLKG_IOSTAT_READ]; |
781 | wbytes = bis->cur.bytes[BLKG_IOSTAT_WRITE]; | |
782 | dbytes = bis->cur.bytes[BLKG_IOSTAT_DISCARD]; | |
783 | rios = bis->cur.ios[BLKG_IOSTAT_READ]; | |
784 | wios = bis->cur.ios[BLKG_IOSTAT_WRITE]; | |
785 | dios = bis->cur.ios[BLKG_IOSTAT_DISCARD]; | |
786 | } while (u64_stats_fetch_retry(&bis->sync, seq)); | |
2ee867dc | 787 | |
903d23f0 JB |
788 | if (rbytes || wbytes || rios || wios) { |
789 | has_stats = true; | |
790 | off += scnprintf(buf+off, size-off, | |
636620b6 TH |
791 | "rbytes=%llu wbytes=%llu rios=%llu wios=%llu dbytes=%llu dios=%llu", |
792 | rbytes, wbytes, rios, wios, | |
793 | dbytes, dios); | |
903d23f0 JB |
794 | } |
795 | ||
07b0fdec | 796 | if (blkcg_debug_stats && atomic_read(&blkg->use_delay)) { |
d09d8df3 JB |
797 | has_stats = true; |
798 | off += scnprintf(buf+off, size-off, | |
799 | " use_delay=%d delay_nsec=%llu", | |
800 | atomic_read(&blkg->use_delay), | |
801 | (unsigned long long)atomic64_read(&blkg->delay_nsec)); | |
802 | } | |
803 | ||
903d23f0 JB |
804 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
805 | struct blkcg_policy *pol = blkcg_policy[i]; | |
806 | size_t written; | |
807 | ||
808 | if (!blkg->pd[i] || !pol->pd_stat_fn) | |
809 | continue; | |
810 | ||
811 | written = pol->pd_stat_fn(blkg->pd[i], buf+off, size-off); | |
812 | if (written) | |
813 | has_stats = true; | |
814 | off += written; | |
815 | } | |
07b0fdec | 816 | |
903d23f0 | 817 | if (has_stats) { |
f539da82 TH |
818 | if (off < size - 1) { |
819 | off += scnprintf(buf+off, size-off, "\n"); | |
820 | seq_commit(sf, off); | |
821 | } else { | |
822 | seq_commit(sf, -1); | |
823 | } | |
903d23f0 | 824 | } |
b0814361 TH |
825 | skip: |
826 | spin_unlock_irq(&blkg->q->queue_lock); | |
2ee867dc TH |
827 | } |
828 | ||
829 | rcu_read_unlock(); | |
830 | return 0; | |
831 | } | |
832 | ||
e1f3b941 | 833 | static struct cftype blkcg_files[] = { |
2ee867dc TH |
834 | { |
835 | .name = "stat", | |
ca0752c5 | 836 | .flags = CFTYPE_NOT_ON_ROOT, |
2ee867dc TH |
837 | .seq_show = blkcg_print_stat, |
838 | }, | |
839 | { } /* terminate */ | |
840 | }; | |
841 | ||
e1f3b941 | 842 | static struct cftype blkcg_legacy_files[] = { |
84c124da DS |
843 | { |
844 | .name = "reset_stats", | |
3c798398 | 845 | .write_u64 = blkcg_reset_stats, |
22084190 | 846 | }, |
4baf6e33 | 847 | { } /* terminate */ |
31e4c28d VG |
848 | }; |
849 | ||
59b57717 DZF |
850 | /* |
851 | * blkcg destruction is a three-stage process. | |
852 | * | |
853 | * 1. Destruction starts. The blkcg_css_offline() callback is invoked | |
854 | * which offlines writeback. Here we tie the next stage of blkg destruction | |
855 | * to the completion of writeback associated with the blkcg. This lets us | |
856 | * avoid punting potentially large amounts of outstanding writeback to root | |
857 | * while maintaining any ongoing policies. The next stage is triggered when | |
858 | * the nr_cgwbs count goes to zero. | |
859 | * | |
860 | * 2. When the nr_cgwbs count goes to zero, blkcg_destroy_blkgs() is called | |
861 | * and handles the destruction of blkgs. Here the css reference held by | |
862 | * the blkg is put back eventually allowing blkcg_css_free() to be called. | |
863 | * This work may occur in cgwb_release_workfn() on the cgwb_release | |
864 | * workqueue. Any submitted ios that fail to get the blkg ref will be | |
865 | * punted to the root_blkg. | |
866 | * | |
867 | * 3. Once the blkcg ref count goes to zero, blkcg_css_free() is called. | |
868 | * This finally frees the blkcg. | |
869 | */ | |
870 | ||
9f13ef67 | 871 | /** |
92fb9748 | 872 | * blkcg_css_offline - cgroup css_offline callback |
eb95419b | 873 | * @css: css of interest |
9f13ef67 | 874 | * |
59b57717 DZF |
875 | * This function is called when @css is about to go away. Here the cgwbs are |
876 | * offlined first and only once writeback associated with the blkcg has | |
877 | * finished do we start step 2 (see above). | |
9f13ef67 | 878 | */ |
eb95419b | 879 | static void blkcg_css_offline(struct cgroup_subsys_state *css) |
31e4c28d | 880 | { |
eb95419b | 881 | struct blkcg *blkcg = css_to_blkcg(css); |
b1c35769 | 882 | |
59b57717 DZF |
883 | /* this prevents anyone from attaching or migrating to this blkcg */ |
884 | wb_blkcg_offline(blkcg); | |
885 | ||
d866dbf6 TH |
886 | /* put the base online pin allowing step 2 to be triggered */ |
887 | blkcg_unpin_online(blkcg); | |
59b57717 DZF |
888 | } |
889 | ||
890 | /** | |
891 | * blkcg_destroy_blkgs - responsible for shooting down blkgs | |
892 | * @blkcg: blkcg of interest | |
893 | * | |
894 | * blkgs should be removed while holding both q and blkcg locks. As blkcg lock | |
895 | * is nested inside q lock, this function performs reverse double lock dancing. | |
896 | * Destroying the blkgs releases the reference held on the blkcg's css allowing | |
897 | * blkcg_css_free to eventually be called. | |
898 | * | |
899 | * This is the blkcg counterpart of ioc_release_fn(). | |
900 | */ | |
901 | void blkcg_destroy_blkgs(struct blkcg *blkcg) | |
902 | { | |
9f13ef67 | 903 | spin_lock_irq(&blkcg->lock); |
7ee9c562 | 904 | |
4c699480 JQ |
905 | while (!hlist_empty(&blkcg->blkg_list)) { |
906 | struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first, | |
6b065462 | 907 | struct blkcg_gq, blkcg_node); |
4c699480 JQ |
908 | struct request_queue *q = blkg->q; |
909 | ||
0d945c1f | 910 | if (spin_trylock(&q->queue_lock)) { |
4c699480 | 911 | blkg_destroy(blkg); |
0d945c1f | 912 | spin_unlock(&q->queue_lock); |
4c699480 JQ |
913 | } else { |
914 | spin_unlock_irq(&blkcg->lock); | |
915 | cpu_relax(); | |
916 | spin_lock_irq(&blkcg->lock); | |
917 | } | |
918 | } | |
6b065462 | 919 | |
4c699480 JQ |
920 | spin_unlock_irq(&blkcg->lock); |
921 | } | |
922 | ||
eb95419b | 923 | static void blkcg_css_free(struct cgroup_subsys_state *css) |
7ee9c562 | 924 | { |
eb95419b | 925 | struct blkcg *blkcg = css_to_blkcg(css); |
bc915e61 | 926 | int i; |
7ee9c562 | 927 | |
7876f930 | 928 | mutex_lock(&blkcg_pol_mutex); |
e4a9bde9 | 929 | |
7876f930 | 930 | list_del(&blkcg->all_blkcgs_node); |
7876f930 | 931 | |
bc915e61 | 932 | for (i = 0; i < BLKCG_MAX_POLS; i++) |
e4a9bde9 TH |
933 | if (blkcg->cpd[i]) |
934 | blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]); | |
935 | ||
936 | mutex_unlock(&blkcg_pol_mutex); | |
937 | ||
bc915e61 | 938 | kfree(blkcg); |
31e4c28d VG |
939 | } |
940 | ||
eb95419b TH |
941 | static struct cgroup_subsys_state * |
942 | blkcg_css_alloc(struct cgroup_subsys_state *parent_css) | |
31e4c28d | 943 | { |
3c798398 | 944 | struct blkcg *blkcg; |
e48453c3 AA |
945 | struct cgroup_subsys_state *ret; |
946 | int i; | |
31e4c28d | 947 | |
7876f930 TH |
948 | mutex_lock(&blkcg_pol_mutex); |
949 | ||
eb95419b | 950 | if (!parent_css) { |
3c798398 | 951 | blkcg = &blkcg_root; |
bc915e61 TH |
952 | } else { |
953 | blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); | |
954 | if (!blkcg) { | |
955 | ret = ERR_PTR(-ENOMEM); | |
4c18c9e9 | 956 | goto unlock; |
bc915e61 | 957 | } |
e48453c3 AA |
958 | } |
959 | ||
960 | for (i = 0; i < BLKCG_MAX_POLS ; i++) { | |
961 | struct blkcg_policy *pol = blkcg_policy[i]; | |
962 | struct blkcg_policy_data *cpd; | |
963 | ||
964 | /* | |
965 | * If the policy hasn't been attached yet, wait for it | |
966 | * to be attached before doing anything else. Otherwise, | |
967 | * check if the policy requires any specific per-cgroup | |
968 | * data: if it does, allocate and initialize it. | |
969 | */ | |
e4a9bde9 | 970 | if (!pol || !pol->cpd_alloc_fn) |
e48453c3 AA |
971 | continue; |
972 | ||
e4a9bde9 | 973 | cpd = pol->cpd_alloc_fn(GFP_KERNEL); |
e48453c3 AA |
974 | if (!cpd) { |
975 | ret = ERR_PTR(-ENOMEM); | |
976 | goto free_pd_blkcg; | |
977 | } | |
81437648 TH |
978 | blkcg->cpd[i] = cpd; |
979 | cpd->blkcg = blkcg; | |
e48453c3 | 980 | cpd->plid = i; |
e4a9bde9 TH |
981 | if (pol->cpd_init_fn) |
982 | pol->cpd_init_fn(cpd); | |
e48453c3 | 983 | } |
31e4c28d | 984 | |
31e4c28d | 985 | spin_lock_init(&blkcg->lock); |
d866dbf6 | 986 | refcount_set(&blkcg->online_pin, 1); |
e00f4f4d | 987 | INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT | __GFP_NOWARN); |
31e4c28d | 988 | INIT_HLIST_HEAD(&blkcg->blkg_list); |
52ebea74 TH |
989 | #ifdef CONFIG_CGROUP_WRITEBACK |
990 | INIT_LIST_HEAD(&blkcg->cgwb_list); | |
991 | #endif | |
7876f930 TH |
992 | list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs); |
993 | ||
994 | mutex_unlock(&blkcg_pol_mutex); | |
31e4c28d | 995 | return &blkcg->css; |
e48453c3 AA |
996 | |
997 | free_pd_blkcg: | |
998 | for (i--; i >= 0; i--) | |
e4a9bde9 TH |
999 | if (blkcg->cpd[i]) |
1000 | blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]); | |
4c18c9e9 | 1001 | |
1002 | if (blkcg != &blkcg_root) | |
1003 | kfree(blkcg); | |
1004 | unlock: | |
7876f930 | 1005 | mutex_unlock(&blkcg_pol_mutex); |
e48453c3 | 1006 | return ret; |
31e4c28d VG |
1007 | } |
1008 | ||
4308a434 TH |
1009 | static int blkcg_css_online(struct cgroup_subsys_state *css) |
1010 | { | |
1011 | struct blkcg *blkcg = css_to_blkcg(css); | |
1012 | struct blkcg *parent = blkcg_parent(blkcg); | |
1013 | ||
1014 | /* | |
1015 | * blkcg_pin_online() is used to delay blkcg offline so that blkgs | |
1016 | * don't go offline while cgwbs are still active on them. Pin the | |
1017 | * parent so that offline always happens towards the root. | |
1018 | */ | |
1019 | if (parent) | |
1020 | blkcg_pin_online(parent); | |
1021 | return 0; | |
1022 | } | |
1023 | ||
5efd6113 TH |
1024 | /** |
1025 | * blkcg_init_queue - initialize blkcg part of request queue | |
1026 | * @q: request_queue to initialize | |
1027 | * | |
3d745ea5 | 1028 | * Called from __blk_alloc_queue(). Responsible for initializing blkcg |
5efd6113 TH |
1029 | * part of new request_queue @q. |
1030 | * | |
1031 | * RETURNS: | |
1032 | * 0 on success, -errno on failure. | |
1033 | */ | |
1034 | int blkcg_init_queue(struct request_queue *q) | |
1035 | { | |
d708f0d5 JA |
1036 | struct blkcg_gq *new_blkg, *blkg; |
1037 | bool preloaded; | |
ec13b1d6 TH |
1038 | int ret; |
1039 | ||
d708f0d5 JA |
1040 | new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL); |
1041 | if (!new_blkg) | |
1042 | return -ENOMEM; | |
1043 | ||
1044 | preloaded = !radix_tree_preload(GFP_KERNEL); | |
1045 | ||
bea54883 | 1046 | /* Make sure the root blkg exists. */ |
ec13b1d6 | 1047 | rcu_read_lock(); |
0d945c1f | 1048 | spin_lock_irq(&q->queue_lock); |
d708f0d5 | 1049 | blkg = blkg_create(&blkcg_root, q, new_blkg); |
901932a3 JB |
1050 | if (IS_ERR(blkg)) |
1051 | goto err_unlock; | |
1052 | q->root_blkg = blkg; | |
0d945c1f | 1053 | spin_unlock_irq(&q->queue_lock); |
ec13b1d6 TH |
1054 | rcu_read_unlock(); |
1055 | ||
d708f0d5 JA |
1056 | if (preloaded) |
1057 | radix_tree_preload_end(); | |
1058 | ||
d7067512 | 1059 | ret = blk_iolatency_init(q); |
04be60b5 CH |
1060 | if (ret) |
1061 | goto err_destroy_all; | |
d7067512 | 1062 | |
ec13b1d6 | 1063 | ret = blk_throtl_init(q); |
04be60b5 CH |
1064 | if (ret) |
1065 | goto err_destroy_all; | |
1066 | return 0; | |
901932a3 | 1067 | |
04be60b5 | 1068 | err_destroy_all: |
04be60b5 | 1069 | blkg_destroy_all(q); |
04be60b5 | 1070 | return ret; |
901932a3 | 1071 | err_unlock: |
0d945c1f | 1072 | spin_unlock_irq(&q->queue_lock); |
901932a3 JB |
1073 | rcu_read_unlock(); |
1074 | if (preloaded) | |
1075 | radix_tree_preload_end(); | |
1076 | return PTR_ERR(blkg); | |
5efd6113 TH |
1077 | } |
1078 | ||
5efd6113 TH |
1079 | /** |
1080 | * blkcg_exit_queue - exit and release blkcg part of request_queue | |
1081 | * @q: request_queue being released | |
1082 | * | |
7585d508 | 1083 | * Called from blk_exit_queue(). Responsible for exiting blkcg part. |
5efd6113 TH |
1084 | */ |
1085 | void blkcg_exit_queue(struct request_queue *q) | |
1086 | { | |
3c96cb32 | 1087 | blkg_destroy_all(q); |
5efd6113 TH |
1088 | blk_throtl_exit(q); |
1089 | } | |
1090 | ||
31e4c28d VG |
1091 | /* |
1092 | * We cannot support shared io contexts, as we have no mean to support | |
1093 | * two tasks with the same ioc in two different groups without major rework | |
1094 | * of the main cic data structures. For now we allow a task to change | |
1095 | * its cgroup only if it's the only owner of its ioc. | |
1096 | */ | |
1f7dd3e5 | 1097 | static int blkcg_can_attach(struct cgroup_taskset *tset) |
31e4c28d | 1098 | { |
bb9d97b6 | 1099 | struct task_struct *task; |
1f7dd3e5 | 1100 | struct cgroup_subsys_state *dst_css; |
31e4c28d VG |
1101 | struct io_context *ioc; |
1102 | int ret = 0; | |
1103 | ||
1104 | /* task_lock() is needed to avoid races with exit_io_context() */ | |
1f7dd3e5 | 1105 | cgroup_taskset_for_each(task, dst_css, tset) { |
bb9d97b6 TH |
1106 | task_lock(task); |
1107 | ioc = task->io_context; | |
1108 | if (ioc && atomic_read(&ioc->nr_tasks) > 1) | |
1109 | ret = -EINVAL; | |
1110 | task_unlock(task); | |
1111 | if (ret) | |
1112 | break; | |
1113 | } | |
31e4c28d VG |
1114 | return ret; |
1115 | } | |
1116 | ||
f7331648 TH |
1117 | static void blkg_iostat_set(struct blkg_iostat *dst, struct blkg_iostat *src) |
1118 | { | |
1119 | int i; | |
1120 | ||
1121 | for (i = 0; i < BLKG_IOSTAT_NR; i++) { | |
1122 | dst->bytes[i] = src->bytes[i]; | |
1123 | dst->ios[i] = src->ios[i]; | |
1124 | } | |
1125 | } | |
1126 | ||
1127 | static void blkg_iostat_add(struct blkg_iostat *dst, struct blkg_iostat *src) | |
1128 | { | |
1129 | int i; | |
1130 | ||
1131 | for (i = 0; i < BLKG_IOSTAT_NR; i++) { | |
1132 | dst->bytes[i] += src->bytes[i]; | |
1133 | dst->ios[i] += src->ios[i]; | |
1134 | } | |
1135 | } | |
1136 | ||
1137 | static void blkg_iostat_sub(struct blkg_iostat *dst, struct blkg_iostat *src) | |
1138 | { | |
1139 | int i; | |
1140 | ||
1141 | for (i = 0; i < BLKG_IOSTAT_NR; i++) { | |
1142 | dst->bytes[i] -= src->bytes[i]; | |
1143 | dst->ios[i] -= src->ios[i]; | |
1144 | } | |
1145 | } | |
1146 | ||
1147 | static void blkcg_rstat_flush(struct cgroup_subsys_state *css, int cpu) | |
1148 | { | |
1149 | struct blkcg *blkcg = css_to_blkcg(css); | |
1150 | struct blkcg_gq *blkg; | |
1151 | ||
1152 | rcu_read_lock(); | |
1153 | ||
1154 | hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { | |
1155 | struct blkcg_gq *parent = blkg->parent; | |
1156 | struct blkg_iostat_set *bisc = per_cpu_ptr(blkg->iostat_cpu, cpu); | |
1157 | struct blkg_iostat cur, delta; | |
1158 | unsigned seq; | |
1159 | ||
1160 | /* fetch the current per-cpu values */ | |
1161 | do { | |
1162 | seq = u64_stats_fetch_begin(&bisc->sync); | |
1163 | blkg_iostat_set(&cur, &bisc->cur); | |
1164 | } while (u64_stats_fetch_retry(&bisc->sync, seq)); | |
1165 | ||
1166 | /* propagate percpu delta to global */ | |
1167 | u64_stats_update_begin(&blkg->iostat.sync); | |
1168 | blkg_iostat_set(&delta, &cur); | |
1169 | blkg_iostat_sub(&delta, &bisc->last); | |
1170 | blkg_iostat_add(&blkg->iostat.cur, &delta); | |
1171 | blkg_iostat_add(&bisc->last, &delta); | |
1172 | u64_stats_update_end(&blkg->iostat.sync); | |
1173 | ||
1174 | /* propagate global delta to parent */ | |
1175 | if (parent) { | |
1176 | u64_stats_update_begin(&parent->iostat.sync); | |
1177 | blkg_iostat_set(&delta, &blkg->iostat.cur); | |
1178 | blkg_iostat_sub(&delta, &blkg->iostat.last); | |
1179 | blkg_iostat_add(&parent->iostat.cur, &delta); | |
1180 | blkg_iostat_add(&blkg->iostat.last, &delta); | |
1181 | u64_stats_update_end(&parent->iostat.sync); | |
1182 | } | |
1183 | } | |
1184 | ||
1185 | rcu_read_unlock(); | |
1186 | } | |
1187 | ||
69d7fde5 TH |
1188 | static void blkcg_bind(struct cgroup_subsys_state *root_css) |
1189 | { | |
1190 | int i; | |
1191 | ||
1192 | mutex_lock(&blkcg_pol_mutex); | |
1193 | ||
1194 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
1195 | struct blkcg_policy *pol = blkcg_policy[i]; | |
1196 | struct blkcg *blkcg; | |
1197 | ||
1198 | if (!pol || !pol->cpd_bind_fn) | |
1199 | continue; | |
1200 | ||
1201 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) | |
1202 | if (blkcg->cpd[pol->plid]) | |
1203 | pol->cpd_bind_fn(blkcg->cpd[pol->plid]); | |
1204 | } | |
1205 | mutex_unlock(&blkcg_pol_mutex); | |
1206 | } | |
1207 | ||
d09d8df3 JB |
1208 | static void blkcg_exit(struct task_struct *tsk) |
1209 | { | |
1210 | if (tsk->throttle_queue) | |
1211 | blk_put_queue(tsk->throttle_queue); | |
1212 | tsk->throttle_queue = NULL; | |
1213 | } | |
1214 | ||
c165b3e3 | 1215 | struct cgroup_subsys io_cgrp_subsys = { |
92fb9748 | 1216 | .css_alloc = blkcg_css_alloc, |
4308a434 | 1217 | .css_online = blkcg_css_online, |
92fb9748 TH |
1218 | .css_offline = blkcg_css_offline, |
1219 | .css_free = blkcg_css_free, | |
3c798398 | 1220 | .can_attach = blkcg_can_attach, |
f7331648 | 1221 | .css_rstat_flush = blkcg_rstat_flush, |
69d7fde5 | 1222 | .bind = blkcg_bind, |
2ee867dc | 1223 | .dfl_cftypes = blkcg_files, |
880f50e2 | 1224 | .legacy_cftypes = blkcg_legacy_files, |
c165b3e3 | 1225 | .legacy_name = "blkio", |
d09d8df3 | 1226 | .exit = blkcg_exit, |
1ced953b TH |
1227 | #ifdef CONFIG_MEMCG |
1228 | /* | |
1229 | * This ensures that, if available, memcg is automatically enabled | |
1230 | * together on the default hierarchy so that the owner cgroup can | |
1231 | * be retrieved from writeback pages. | |
1232 | */ | |
1233 | .depends_on = 1 << memory_cgrp_id, | |
1234 | #endif | |
676f7c8f | 1235 | }; |
c165b3e3 | 1236 | EXPORT_SYMBOL_GPL(io_cgrp_subsys); |
676f7c8f | 1237 | |
a2b1693b TH |
1238 | /** |
1239 | * blkcg_activate_policy - activate a blkcg policy on a request_queue | |
1240 | * @q: request_queue of interest | |
1241 | * @pol: blkcg policy to activate | |
1242 | * | |
1243 | * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through | |
1244 | * bypass mode to populate its blkgs with policy_data for @pol. | |
1245 | * | |
1246 | * Activation happens with @q bypassed, so nobody would be accessing blkgs | |
1247 | * from IO path. Update of each blkg is protected by both queue and blkcg | |
1248 | * locks so that holding either lock and testing blkcg_policy_enabled() is | |
1249 | * always enough for dereferencing policy data. | |
1250 | * | |
1251 | * The caller is responsible for synchronizing [de]activations and policy | |
1252 | * [un]registerations. Returns 0 on success, -errno on failure. | |
1253 | */ | |
1254 | int blkcg_activate_policy(struct request_queue *q, | |
3c798398 | 1255 | const struct blkcg_policy *pol) |
a2b1693b | 1256 | { |
4c55f4f9 | 1257 | struct blkg_policy_data *pd_prealloc = NULL; |
9d179b86 | 1258 | struct blkcg_gq *blkg, *pinned_blkg = NULL; |
4c55f4f9 | 1259 | int ret; |
a2b1693b TH |
1260 | |
1261 | if (blkcg_policy_enabled(q, pol)) | |
1262 | return 0; | |
1263 | ||
344e9ffc | 1264 | if (queue_is_mq(q)) |
bd166ef1 | 1265 | blk_mq_freeze_queue(q); |
9d179b86 | 1266 | retry: |
0d945c1f | 1267 | spin_lock_irq(&q->queue_lock); |
a2b1693b | 1268 | |
9d179b86 | 1269 | /* blkg_list is pushed at the head, reverse walk to allocate parents first */ |
71c81407 | 1270 | list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) { |
4c55f4f9 TH |
1271 | struct blkg_policy_data *pd; |
1272 | ||
1273 | if (blkg->pd[pol->plid]) | |
1274 | continue; | |
a2b1693b | 1275 | |
9d179b86 TH |
1276 | /* If prealloc matches, use it; otherwise try GFP_NOWAIT */ |
1277 | if (blkg == pinned_blkg) { | |
1278 | pd = pd_prealloc; | |
1279 | pd_prealloc = NULL; | |
1280 | } else { | |
1281 | pd = pol->pd_alloc_fn(GFP_NOWAIT | __GFP_NOWARN, q, | |
1282 | blkg->blkcg); | |
1283 | } | |
1284 | ||
4c55f4f9 | 1285 | if (!pd) { |
9d179b86 TH |
1286 | /* |
1287 | * GFP_NOWAIT failed. Free the existing one and | |
1288 | * prealloc for @blkg w/ GFP_KERNEL. | |
1289 | */ | |
1290 | if (pinned_blkg) | |
1291 | blkg_put(pinned_blkg); | |
1292 | blkg_get(blkg); | |
1293 | pinned_blkg = blkg; | |
1294 | ||
0d945c1f | 1295 | spin_unlock_irq(&q->queue_lock); |
9d179b86 TH |
1296 | |
1297 | if (pd_prealloc) | |
1298 | pol->pd_free_fn(pd_prealloc); | |
1299 | pd_prealloc = pol->pd_alloc_fn(GFP_KERNEL, q, | |
1300 | blkg->blkcg); | |
1301 | if (pd_prealloc) | |
1302 | goto retry; | |
1303 | else | |
1304 | goto enomem; | |
4c55f4f9 | 1305 | } |
a2b1693b TH |
1306 | |
1307 | blkg->pd[pol->plid] = pd; | |
1308 | pd->blkg = blkg; | |
b276a876 | 1309 | pd->plid = pol->plid; |
a2b1693b TH |
1310 | } |
1311 | ||
9d179b86 TH |
1312 | /* all allocated, init in the same order */ |
1313 | if (pol->pd_init_fn) | |
1314 | list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) | |
1315 | pol->pd_init_fn(blkg->pd[pol->plid]); | |
1316 | ||
a2b1693b TH |
1317 | __set_bit(pol->plid, q->blkcg_pols); |
1318 | ret = 0; | |
4c55f4f9 | 1319 | |
0d945c1f | 1320 | spin_unlock_irq(&q->queue_lock); |
9d179b86 | 1321 | out: |
344e9ffc | 1322 | if (queue_is_mq(q)) |
bd166ef1 | 1323 | blk_mq_unfreeze_queue(q); |
9d179b86 TH |
1324 | if (pinned_blkg) |
1325 | blkg_put(pinned_blkg); | |
001bea73 TH |
1326 | if (pd_prealloc) |
1327 | pol->pd_free_fn(pd_prealloc); | |
a2b1693b | 1328 | return ret; |
9d179b86 TH |
1329 | |
1330 | enomem: | |
1331 | /* alloc failed, nothing's initialized yet, free everything */ | |
1332 | spin_lock_irq(&q->queue_lock); | |
1333 | list_for_each_entry(blkg, &q->blkg_list, q_node) { | |
1334 | if (blkg->pd[pol->plid]) { | |
1335 | pol->pd_free_fn(blkg->pd[pol->plid]); | |
1336 | blkg->pd[pol->plid] = NULL; | |
1337 | } | |
1338 | } | |
1339 | spin_unlock_irq(&q->queue_lock); | |
1340 | ret = -ENOMEM; | |
1341 | goto out; | |
a2b1693b TH |
1342 | } |
1343 | EXPORT_SYMBOL_GPL(blkcg_activate_policy); | |
1344 | ||
1345 | /** | |
1346 | * blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue | |
1347 | * @q: request_queue of interest | |
1348 | * @pol: blkcg policy to deactivate | |
1349 | * | |
1350 | * Deactivate @pol on @q. Follows the same synchronization rules as | |
1351 | * blkcg_activate_policy(). | |
1352 | */ | |
1353 | void blkcg_deactivate_policy(struct request_queue *q, | |
3c798398 | 1354 | const struct blkcg_policy *pol) |
a2b1693b | 1355 | { |
3c798398 | 1356 | struct blkcg_gq *blkg; |
a2b1693b TH |
1357 | |
1358 | if (!blkcg_policy_enabled(q, pol)) | |
1359 | return; | |
1360 | ||
344e9ffc | 1361 | if (queue_is_mq(q)) |
bd166ef1 | 1362 | blk_mq_freeze_queue(q); |
bd166ef1 | 1363 | |
0d945c1f | 1364 | spin_lock_irq(&q->queue_lock); |
a2b1693b TH |
1365 | |
1366 | __clear_bit(pol->plid, q->blkcg_pols); | |
1367 | ||
1368 | list_for_each_entry(blkg, &q->blkg_list, q_node) { | |
001bea73 | 1369 | if (blkg->pd[pol->plid]) { |
6b065462 | 1370 | if (pol->pd_offline_fn) |
a9520cd6 | 1371 | pol->pd_offline_fn(blkg->pd[pol->plid]); |
001bea73 TH |
1372 | pol->pd_free_fn(blkg->pd[pol->plid]); |
1373 | blkg->pd[pol->plid] = NULL; | |
1374 | } | |
a2b1693b TH |
1375 | } |
1376 | ||
0d945c1f | 1377 | spin_unlock_irq(&q->queue_lock); |
bd166ef1 | 1378 | |
344e9ffc | 1379 | if (queue_is_mq(q)) |
bd166ef1 | 1380 | blk_mq_unfreeze_queue(q); |
a2b1693b TH |
1381 | } |
1382 | EXPORT_SYMBOL_GPL(blkcg_deactivate_policy); | |
1383 | ||
8bd435b3 | 1384 | /** |
3c798398 TH |
1385 | * blkcg_policy_register - register a blkcg policy |
1386 | * @pol: blkcg policy to register | |
8bd435b3 | 1387 | * |
3c798398 TH |
1388 | * Register @pol with blkcg core. Might sleep and @pol may be modified on |
1389 | * successful registration. Returns 0 on success and -errno on failure. | |
8bd435b3 | 1390 | */ |
d5bf0291 | 1391 | int blkcg_policy_register(struct blkcg_policy *pol) |
3e252066 | 1392 | { |
06b285bd | 1393 | struct blkcg *blkcg; |
8bd435b3 | 1394 | int i, ret; |
e8989fae | 1395 | |
838f13bf | 1396 | mutex_lock(&blkcg_pol_register_mutex); |
bc0d6501 TH |
1397 | mutex_lock(&blkcg_pol_mutex); |
1398 | ||
8bd435b3 TH |
1399 | /* find an empty slot */ |
1400 | ret = -ENOSPC; | |
1401 | for (i = 0; i < BLKCG_MAX_POLS; i++) | |
3c798398 | 1402 | if (!blkcg_policy[i]) |
8bd435b3 | 1403 | break; |
01c5f85a JA |
1404 | if (i >= BLKCG_MAX_POLS) { |
1405 | pr_warn("blkcg_policy_register: BLKCG_MAX_POLS too small\n"); | |
838f13bf | 1406 | goto err_unlock; |
01c5f85a | 1407 | } |
035d10b2 | 1408 | |
e8401073 | 1409 | /* Make sure cpd/pd_alloc_fn and cpd/pd_free_fn in pairs */ |
1410 | if ((!pol->cpd_alloc_fn ^ !pol->cpd_free_fn) || | |
1411 | (!pol->pd_alloc_fn ^ !pol->pd_free_fn)) | |
1412 | goto err_unlock; | |
1413 | ||
06b285bd | 1414 | /* register @pol */ |
3c798398 | 1415 | pol->plid = i; |
06b285bd TH |
1416 | blkcg_policy[pol->plid] = pol; |
1417 | ||
1418 | /* allocate and install cpd's */ | |
e4a9bde9 | 1419 | if (pol->cpd_alloc_fn) { |
06b285bd TH |
1420 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
1421 | struct blkcg_policy_data *cpd; | |
1422 | ||
e4a9bde9 | 1423 | cpd = pol->cpd_alloc_fn(GFP_KERNEL); |
bbb427e3 | 1424 | if (!cpd) |
06b285bd | 1425 | goto err_free_cpds; |
06b285bd | 1426 | |
81437648 TH |
1427 | blkcg->cpd[pol->plid] = cpd; |
1428 | cpd->blkcg = blkcg; | |
06b285bd | 1429 | cpd->plid = pol->plid; |
86a5bba5 TH |
1430 | if (pol->cpd_init_fn) |
1431 | pol->cpd_init_fn(cpd); | |
06b285bd TH |
1432 | } |
1433 | } | |
1434 | ||
838f13bf | 1435 | mutex_unlock(&blkcg_pol_mutex); |
8bd435b3 | 1436 | |
8bd435b3 | 1437 | /* everything is in place, add intf files for the new policy */ |
2ee867dc TH |
1438 | if (pol->dfl_cftypes) |
1439 | WARN_ON(cgroup_add_dfl_cftypes(&io_cgrp_subsys, | |
1440 | pol->dfl_cftypes)); | |
880f50e2 | 1441 | if (pol->legacy_cftypes) |
c165b3e3 | 1442 | WARN_ON(cgroup_add_legacy_cftypes(&io_cgrp_subsys, |
880f50e2 | 1443 | pol->legacy_cftypes)); |
838f13bf TH |
1444 | mutex_unlock(&blkcg_pol_register_mutex); |
1445 | return 0; | |
1446 | ||
06b285bd | 1447 | err_free_cpds: |
58a9edce | 1448 | if (pol->cpd_free_fn) { |
06b285bd | 1449 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
e4a9bde9 TH |
1450 | if (blkcg->cpd[pol->plid]) { |
1451 | pol->cpd_free_fn(blkcg->cpd[pol->plid]); | |
1452 | blkcg->cpd[pol->plid] = NULL; | |
1453 | } | |
06b285bd TH |
1454 | } |
1455 | } | |
1456 | blkcg_policy[pol->plid] = NULL; | |
838f13bf | 1457 | err_unlock: |
bc0d6501 | 1458 | mutex_unlock(&blkcg_pol_mutex); |
838f13bf | 1459 | mutex_unlock(&blkcg_pol_register_mutex); |
8bd435b3 | 1460 | return ret; |
3e252066 | 1461 | } |
3c798398 | 1462 | EXPORT_SYMBOL_GPL(blkcg_policy_register); |
3e252066 | 1463 | |
8bd435b3 | 1464 | /** |
3c798398 TH |
1465 | * blkcg_policy_unregister - unregister a blkcg policy |
1466 | * @pol: blkcg policy to unregister | |
8bd435b3 | 1467 | * |
3c798398 | 1468 | * Undo blkcg_policy_register(@pol). Might sleep. |
8bd435b3 | 1469 | */ |
3c798398 | 1470 | void blkcg_policy_unregister(struct blkcg_policy *pol) |
3e252066 | 1471 | { |
06b285bd TH |
1472 | struct blkcg *blkcg; |
1473 | ||
838f13bf | 1474 | mutex_lock(&blkcg_pol_register_mutex); |
bc0d6501 | 1475 | |
3c798398 | 1476 | if (WARN_ON(blkcg_policy[pol->plid] != pol)) |
8bd435b3 TH |
1477 | goto out_unlock; |
1478 | ||
1479 | /* kill the intf files first */ | |
2ee867dc TH |
1480 | if (pol->dfl_cftypes) |
1481 | cgroup_rm_cftypes(pol->dfl_cftypes); | |
880f50e2 TH |
1482 | if (pol->legacy_cftypes) |
1483 | cgroup_rm_cftypes(pol->legacy_cftypes); | |
44ea53de | 1484 | |
06b285bd | 1485 | /* remove cpds and unregister */ |
838f13bf | 1486 | mutex_lock(&blkcg_pol_mutex); |
06b285bd | 1487 | |
58a9edce | 1488 | if (pol->cpd_free_fn) { |
06b285bd | 1489 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
e4a9bde9 TH |
1490 | if (blkcg->cpd[pol->plid]) { |
1491 | pol->cpd_free_fn(blkcg->cpd[pol->plid]); | |
1492 | blkcg->cpd[pol->plid] = NULL; | |
1493 | } | |
06b285bd TH |
1494 | } |
1495 | } | |
3c798398 | 1496 | blkcg_policy[pol->plid] = NULL; |
06b285bd | 1497 | |
bc0d6501 | 1498 | mutex_unlock(&blkcg_pol_mutex); |
838f13bf TH |
1499 | out_unlock: |
1500 | mutex_unlock(&blkcg_pol_register_mutex); | |
3e252066 | 1501 | } |
3c798398 | 1502 | EXPORT_SYMBOL_GPL(blkcg_policy_unregister); |
903d23f0 | 1503 | |
d3f77dfd TH |
1504 | bool __blkcg_punt_bio_submit(struct bio *bio) |
1505 | { | |
1506 | struct blkcg_gq *blkg = bio->bi_blkg; | |
1507 | ||
1508 | /* consume the flag first */ | |
1509 | bio->bi_opf &= ~REQ_CGROUP_PUNT; | |
1510 | ||
1511 | /* never bounce for the root cgroup */ | |
1512 | if (!blkg->parent) | |
1513 | return false; | |
1514 | ||
1515 | spin_lock_bh(&blkg->async_bio_lock); | |
1516 | bio_list_add(&blkg->async_bios, bio); | |
1517 | spin_unlock_bh(&blkg->async_bio_lock); | |
1518 | ||
1519 | queue_work(blkcg_punt_bio_wq, &blkg->async_bio_work); | |
1520 | return true; | |
1521 | } | |
1522 | ||
d09d8df3 JB |
1523 | /* |
1524 | * Scale the accumulated delay based on how long it has been since we updated | |
1525 | * the delay. We only call this when we are adding delay, in case it's been a | |
1526 | * while since we added delay, and when we are checking to see if we need to | |
1527 | * delay a task, to account for any delays that may have occurred. | |
1528 | */ | |
1529 | static void blkcg_scale_delay(struct blkcg_gq *blkg, u64 now) | |
1530 | { | |
1531 | u64 old = atomic64_read(&blkg->delay_start); | |
1532 | ||
1533 | /* | |
1534 | * We only want to scale down every second. The idea here is that we | |
1535 | * want to delay people for min(delay_nsec, NSEC_PER_SEC) in a certain | |
1536 | * time window. We only want to throttle tasks for recent delay that | |
1537 | * has occurred, in 1 second time windows since that's the maximum | |
1538 | * things can be throttled. We save the current delay window in | |
1539 | * blkg->last_delay so we know what amount is still left to be charged | |
1540 | * to the blkg from this point onward. blkg->last_use keeps track of | |
1541 | * the use_delay counter. The idea is if we're unthrottling the blkg we | |
1542 | * are ok with whatever is happening now, and we can take away more of | |
1543 | * the accumulated delay as we've already throttled enough that | |
1544 | * everybody is happy with their IO latencies. | |
1545 | */ | |
1546 | if (time_before64(old + NSEC_PER_SEC, now) && | |
1547 | atomic64_cmpxchg(&blkg->delay_start, old, now) == old) { | |
1548 | u64 cur = atomic64_read(&blkg->delay_nsec); | |
1549 | u64 sub = min_t(u64, blkg->last_delay, now - old); | |
1550 | int cur_use = atomic_read(&blkg->use_delay); | |
1551 | ||
1552 | /* | |
1553 | * We've been unthrottled, subtract a larger chunk of our | |
1554 | * accumulated delay. | |
1555 | */ | |
1556 | if (cur_use < blkg->last_use) | |
1557 | sub = max_t(u64, sub, blkg->last_delay >> 1); | |
1558 | ||
1559 | /* | |
1560 | * This shouldn't happen, but handle it anyway. Our delay_nsec | |
1561 | * should only ever be growing except here where we subtract out | |
1562 | * min(last_delay, 1 second), but lord knows bugs happen and I'd | |
1563 | * rather not end up with negative numbers. | |
1564 | */ | |
1565 | if (unlikely(cur < sub)) { | |
1566 | atomic64_set(&blkg->delay_nsec, 0); | |
1567 | blkg->last_delay = 0; | |
1568 | } else { | |
1569 | atomic64_sub(sub, &blkg->delay_nsec); | |
1570 | blkg->last_delay = cur - sub; | |
1571 | } | |
1572 | blkg->last_use = cur_use; | |
1573 | } | |
1574 | } | |
1575 | ||
1576 | /* | |
1577 | * This is called when we want to actually walk up the hierarchy and check to | |
1578 | * see if we need to throttle, and then actually throttle if there is some | |
1579 | * accumulated delay. This should only be called upon return to user space so | |
1580 | * we're not holding some lock that would induce a priority inversion. | |
1581 | */ | |
1582 | static void blkcg_maybe_throttle_blkg(struct blkcg_gq *blkg, bool use_memdelay) | |
1583 | { | |
fd112c74 | 1584 | unsigned long pflags; |
d09d8df3 JB |
1585 | u64 now = ktime_to_ns(ktime_get()); |
1586 | u64 exp; | |
1587 | u64 delay_nsec = 0; | |
1588 | int tok; | |
1589 | ||
1590 | while (blkg->parent) { | |
1591 | if (atomic_read(&blkg->use_delay)) { | |
1592 | blkcg_scale_delay(blkg, now); | |
1593 | delay_nsec = max_t(u64, delay_nsec, | |
1594 | atomic64_read(&blkg->delay_nsec)); | |
1595 | } | |
1596 | blkg = blkg->parent; | |
1597 | } | |
1598 | ||
1599 | if (!delay_nsec) | |
1600 | return; | |
1601 | ||
1602 | /* | |
1603 | * Let's not sleep for all eternity if we've amassed a huge delay. | |
1604 | * Swapping or metadata IO can accumulate 10's of seconds worth of | |
1605 | * delay, and we want userspace to be able to do _something_ so cap the | |
1606 | * delays at 1 second. If there's 10's of seconds worth of delay then | |
1607 | * the tasks will be delayed for 1 second for every syscall. | |
1608 | */ | |
1609 | delay_nsec = min_t(u64, delay_nsec, 250 * NSEC_PER_MSEC); | |
1610 | ||
fd112c74 JB |
1611 | if (use_memdelay) |
1612 | psi_memstall_enter(&pflags); | |
d09d8df3 JB |
1613 | |
1614 | exp = ktime_add_ns(now, delay_nsec); | |
1615 | tok = io_schedule_prepare(); | |
1616 | do { | |
1617 | __set_current_state(TASK_KILLABLE); | |
1618 | if (!schedule_hrtimeout(&exp, HRTIMER_MODE_ABS)) | |
1619 | break; | |
1620 | } while (!fatal_signal_pending(current)); | |
1621 | io_schedule_finish(tok); | |
fd112c74 JB |
1622 | |
1623 | if (use_memdelay) | |
1624 | psi_memstall_leave(&pflags); | |
d09d8df3 JB |
1625 | } |
1626 | ||
1627 | /** | |
1628 | * blkcg_maybe_throttle_current - throttle the current task if it has been marked | |
1629 | * | |
1630 | * This is only called if we've been marked with set_notify_resume(). Obviously | |
1631 | * we can be set_notify_resume() for reasons other than blkcg throttling, so we | |
1632 | * check to see if current->throttle_queue is set and if not this doesn't do | |
1633 | * anything. This should only ever be called by the resume code, it's not meant | |
1634 | * to be called by people willy-nilly as it will actually do the work to | |
1635 | * throttle the task if it is setup for throttling. | |
1636 | */ | |
1637 | void blkcg_maybe_throttle_current(void) | |
1638 | { | |
1639 | struct request_queue *q = current->throttle_queue; | |
1640 | struct cgroup_subsys_state *css; | |
1641 | struct blkcg *blkcg; | |
1642 | struct blkcg_gq *blkg; | |
1643 | bool use_memdelay = current->use_memdelay; | |
1644 | ||
1645 | if (!q) | |
1646 | return; | |
1647 | ||
1648 | current->throttle_queue = NULL; | |
1649 | current->use_memdelay = false; | |
1650 | ||
1651 | rcu_read_lock(); | |
1652 | css = kthread_blkcg(); | |
1653 | if (css) | |
1654 | blkcg = css_to_blkcg(css); | |
1655 | else | |
1656 | blkcg = css_to_blkcg(task_css(current, io_cgrp_id)); | |
1657 | ||
1658 | if (!blkcg) | |
1659 | goto out; | |
1660 | blkg = blkg_lookup(blkcg, q); | |
1661 | if (!blkg) | |
1662 | goto out; | |
7754f669 | 1663 | if (!blkg_tryget(blkg)) |
d09d8df3 JB |
1664 | goto out; |
1665 | rcu_read_unlock(); | |
d09d8df3 JB |
1666 | |
1667 | blkcg_maybe_throttle_blkg(blkg, use_memdelay); | |
1668 | blkg_put(blkg); | |
cc7ecc25 | 1669 | blk_put_queue(q); |
d09d8df3 JB |
1670 | return; |
1671 | out: | |
1672 | rcu_read_unlock(); | |
1673 | blk_put_queue(q); | |
1674 | } | |
d09d8df3 JB |
1675 | |
1676 | /** | |
1677 | * blkcg_schedule_throttle - this task needs to check for throttling | |
537d71b3 BVA |
1678 | * @q: the request queue IO was submitted on |
1679 | * @use_memdelay: do we charge this to memory delay for PSI | |
d09d8df3 JB |
1680 | * |
1681 | * This is called by the IO controller when we know there's delay accumulated | |
1682 | * for the blkg for this task. We do not pass the blkg because there are places | |
1683 | * we call this that may not have that information, the swapping code for | |
1684 | * instance will only have a request_queue at that point. This set's the | |
1685 | * notify_resume for the task to check and see if it requires throttling before | |
1686 | * returning to user space. | |
1687 | * | |
1688 | * We will only schedule once per syscall. You can call this over and over | |
1689 | * again and it will only do the check once upon return to user space, and only | |
1690 | * throttle once. If the task needs to be throttled again it'll need to be | |
1691 | * re-set at the next time we see the task. | |
1692 | */ | |
1693 | void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay) | |
1694 | { | |
1695 | if (unlikely(current->flags & PF_KTHREAD)) | |
1696 | return; | |
1697 | ||
1698 | if (!blk_get_queue(q)) | |
1699 | return; | |
1700 | ||
1701 | if (current->throttle_queue) | |
1702 | blk_put_queue(current->throttle_queue); | |
1703 | current->throttle_queue = q; | |
1704 | if (use_memdelay) | |
1705 | current->use_memdelay = use_memdelay; | |
1706 | set_notify_resume(current); | |
1707 | } | |
d09d8df3 JB |
1708 | |
1709 | /** | |
1710 | * blkcg_add_delay - add delay to this blkg | |
537d71b3 BVA |
1711 | * @blkg: blkg of interest |
1712 | * @now: the current time in nanoseconds | |
1713 | * @delta: how many nanoseconds of delay to add | |
d09d8df3 JB |
1714 | * |
1715 | * Charge @delta to the blkg's current delay accumulation. This is used to | |
1716 | * throttle tasks if an IO controller thinks we need more throttling. | |
1717 | */ | |
1718 | void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta) | |
1719 | { | |
1720 | blkcg_scale_delay(blkg, now); | |
1721 | atomic64_add(delta, &blkg->delay_nsec); | |
1722 | } | |
d09d8df3 | 1723 | |
d3f77dfd TH |
1724 | static int __init blkcg_init(void) |
1725 | { | |
1726 | blkcg_punt_bio_wq = alloc_workqueue("blkcg_punt_bio", | |
1727 | WQ_MEM_RECLAIM | WQ_FREEZABLE | | |
1728 | WQ_UNBOUND | WQ_SYSFS, 0); | |
1729 | if (!blkcg_punt_bio_wq) | |
1730 | return -ENOMEM; | |
1731 | return 0; | |
1732 | } | |
1733 | subsys_initcall(blkcg_init); | |
1734 | ||
903d23f0 JB |
1735 | module_param(blkcg_debug_stats, bool, 0644); |
1736 | MODULE_PARM_DESC(blkcg_debug_stats, "True if you want debug stats, false if not"); |