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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" |
556910e3 | 34 | #include "blk-ioprio.h" |
a7b36ee6 | 35 | #include "blk-throttle.h" |
3e252066 | 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 | |
a731763f YK |
60 | #define BLKG_DESTROY_BATCH_SIZE 64 |
61 | ||
a2b1693b | 62 | static bool blkcg_policy_enabled(struct request_queue *q, |
3c798398 | 63 | const struct blkcg_policy *pol) |
a2b1693b TH |
64 | { |
65 | return pol && test_bit(pol->plid, q->blkcg_pols); | |
66 | } | |
67 | ||
0381411e TH |
68 | /** |
69 | * blkg_free - free a blkg | |
70 | * @blkg: blkg to free | |
71 | * | |
72 | * Free @blkg which may be partially allocated. | |
73 | */ | |
3c798398 | 74 | static void blkg_free(struct blkcg_gq *blkg) |
0381411e | 75 | { |
e8989fae | 76 | int i; |
549d3aa8 TH |
77 | |
78 | if (!blkg) | |
79 | return; | |
80 | ||
db613670 | 81 | for (i = 0; i < BLKCG_MAX_POLS; i++) |
001bea73 TH |
82 | if (blkg->pd[i]) |
83 | blkcg_policy[i]->pd_free_fn(blkg->pd[i]); | |
e8989fae | 84 | |
f7331648 | 85 | free_percpu(blkg->iostat_cpu); |
ef069b97 | 86 | percpu_ref_exit(&blkg->refcnt); |
549d3aa8 | 87 | kfree(blkg); |
0381411e TH |
88 | } |
89 | ||
7fcf2b03 DZ |
90 | static void __blkg_release(struct rcu_head *rcu) |
91 | { | |
92 | struct blkcg_gq *blkg = container_of(rcu, struct blkcg_gq, rcu_head); | |
93 | ||
d3f77dfd TH |
94 | WARN_ON(!bio_list_empty(&blkg->async_bios)); |
95 | ||
7fcf2b03 DZ |
96 | /* release the blkcg and parent blkg refs this blkg has been holding */ |
97 | css_put(&blkg->blkcg->css); | |
98 | if (blkg->parent) | |
99 | blkg_put(blkg->parent); | |
7fcf2b03 DZ |
100 | blkg_free(blkg); |
101 | } | |
102 | ||
103 | /* | |
104 | * A group is RCU protected, but having an rcu lock does not mean that one | |
105 | * can access all the fields of blkg and assume these are valid. For | |
106 | * example, don't try to follow throtl_data and request queue links. | |
107 | * | |
108 | * Having a reference to blkg under an rcu allows accesses to only values | |
109 | * local to groups like group stats and group rate limits. | |
110 | */ | |
111 | static void blkg_release(struct percpu_ref *ref) | |
112 | { | |
113 | struct blkcg_gq *blkg = container_of(ref, struct blkcg_gq, refcnt); | |
114 | ||
115 | call_rcu(&blkg->rcu_head, __blkg_release); | |
116 | } | |
117 | ||
d3f77dfd TH |
118 | static void blkg_async_bio_workfn(struct work_struct *work) |
119 | { | |
120 | struct blkcg_gq *blkg = container_of(work, struct blkcg_gq, | |
121 | async_bio_work); | |
122 | struct bio_list bios = BIO_EMPTY_LIST; | |
123 | struct bio *bio; | |
192f1c6b XT |
124 | struct blk_plug plug; |
125 | bool need_plug = false; | |
d3f77dfd TH |
126 | |
127 | /* as long as there are pending bios, @blkg can't go away */ | |
128 | spin_lock_bh(&blkg->async_bio_lock); | |
129 | bio_list_merge(&bios, &blkg->async_bios); | |
130 | bio_list_init(&blkg->async_bios); | |
131 | spin_unlock_bh(&blkg->async_bio_lock); | |
132 | ||
192f1c6b XT |
133 | /* start plug only when bio_list contains at least 2 bios */ |
134 | if (bios.head && bios.head->bi_next) { | |
135 | need_plug = true; | |
136 | blk_start_plug(&plug); | |
137 | } | |
d3f77dfd TH |
138 | while ((bio = bio_list_pop(&bios))) |
139 | submit_bio(bio); | |
192f1c6b XT |
140 | if (need_plug) |
141 | blk_finish_plug(&plug); | |
d3f77dfd TH |
142 | } |
143 | ||
0381411e TH |
144 | /** |
145 | * blkg_alloc - allocate a blkg | |
146 | * @blkcg: block cgroup the new blkg is associated with | |
147 | * @q: request_queue the new blkg is associated with | |
15974993 | 148 | * @gfp_mask: allocation mask to use |
0381411e | 149 | * |
e8989fae | 150 | * Allocate a new blkg assocating @blkcg and @q. |
0381411e | 151 | */ |
15974993 TH |
152 | static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, |
153 | gfp_t gfp_mask) | |
0381411e | 154 | { |
3c798398 | 155 | struct blkcg_gq *blkg; |
f7331648 | 156 | int i, cpu; |
0381411e TH |
157 | |
158 | /* alloc and init base part */ | |
15974993 | 159 | blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node); |
0381411e TH |
160 | if (!blkg) |
161 | return NULL; | |
162 | ||
ef069b97 TH |
163 | if (percpu_ref_init(&blkg->refcnt, blkg_release, 0, gfp_mask)) |
164 | goto err_free; | |
165 | ||
f7331648 TH |
166 | blkg->iostat_cpu = alloc_percpu_gfp(struct blkg_iostat_set, gfp_mask); |
167 | if (!blkg->iostat_cpu) | |
77ea7338 TH |
168 | goto err_free; |
169 | ||
c875f4d0 | 170 | blkg->q = q; |
e8989fae | 171 | INIT_LIST_HEAD(&blkg->q_node); |
d3f77dfd TH |
172 | spin_lock_init(&blkg->async_bio_lock); |
173 | bio_list_init(&blkg->async_bios); | |
174 | INIT_WORK(&blkg->async_bio_work, blkg_async_bio_workfn); | |
0381411e | 175 | blkg->blkcg = blkcg; |
0381411e | 176 | |
f7331648 TH |
177 | u64_stats_init(&blkg->iostat.sync); |
178 | for_each_possible_cpu(cpu) | |
179 | u64_stats_init(&per_cpu_ptr(blkg->iostat_cpu, cpu)->sync); | |
180 | ||
8bd435b3 | 181 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
3c798398 | 182 | struct blkcg_policy *pol = blkcg_policy[i]; |
e8989fae | 183 | struct blkg_policy_data *pd; |
0381411e | 184 | |
a2b1693b | 185 | if (!blkcg_policy_enabled(q, pol)) |
e8989fae TH |
186 | continue; |
187 | ||
188 | /* alloc per-policy data and attach it to blkg */ | |
cf09a8ee | 189 | pd = pol->pd_alloc_fn(gfp_mask, q, blkcg); |
a051661c TH |
190 | if (!pd) |
191 | goto err_free; | |
549d3aa8 | 192 | |
e8989fae TH |
193 | blkg->pd[i] = pd; |
194 | pd->blkg = blkg; | |
b276a876 | 195 | pd->plid = i; |
e8989fae TH |
196 | } |
197 | ||
0381411e | 198 | return blkg; |
a051661c TH |
199 | |
200 | err_free: | |
201 | blkg_free(blkg); | |
202 | return NULL; | |
0381411e TH |
203 | } |
204 | ||
24f29046 TH |
205 | struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg, |
206 | struct request_queue *q, bool update_hint) | |
80fd9979 | 207 | { |
3c798398 | 208 | struct blkcg_gq *blkg; |
80fd9979 | 209 | |
a637120e | 210 | /* |
86cde6b6 TH |
211 | * Hint didn't match. Look up from the radix tree. Note that the |
212 | * hint can only be updated under queue_lock as otherwise @blkg | |
213 | * could have already been removed from blkg_tree. The caller is | |
214 | * responsible for grabbing queue_lock if @update_hint. | |
a637120e TH |
215 | */ |
216 | blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); | |
86cde6b6 TH |
217 | if (blkg && blkg->q == q) { |
218 | if (update_hint) { | |
0d945c1f | 219 | lockdep_assert_held(&q->queue_lock); |
86cde6b6 TH |
220 | rcu_assign_pointer(blkcg->blkg_hint, blkg); |
221 | } | |
a637120e | 222 | return blkg; |
86cde6b6 | 223 | } |
a637120e | 224 | |
80fd9979 TH |
225 | return NULL; |
226 | } | |
ae118896 | 227 | EXPORT_SYMBOL_GPL(blkg_lookup_slowpath); |
80fd9979 | 228 | |
15974993 | 229 | /* |
d708f0d5 JA |
230 | * If @new_blkg is %NULL, this function tries to allocate a new one as |
231 | * necessary using %GFP_NOWAIT. @new_blkg is always consumed on return. | |
15974993 | 232 | */ |
86cde6b6 | 233 | static struct blkcg_gq *blkg_create(struct blkcg *blkcg, |
d708f0d5 JA |
234 | struct request_queue *q, |
235 | struct blkcg_gq *new_blkg) | |
5624a4e4 | 236 | { |
d708f0d5 | 237 | struct blkcg_gq *blkg; |
f427d909 | 238 | int i, ret; |
5624a4e4 | 239 | |
cd1604fa | 240 | WARN_ON_ONCE(!rcu_read_lock_held()); |
0d945c1f | 241 | lockdep_assert_held(&q->queue_lock); |
cd1604fa | 242 | |
0273ac34 DZ |
243 | /* request_queue is dying, do not create/recreate a blkg */ |
244 | if (blk_queue_dying(q)) { | |
245 | ret = -ENODEV; | |
246 | goto err_free_blkg; | |
247 | } | |
248 | ||
7ee9c562 | 249 | /* blkg holds a reference to blkcg */ |
ec903c0c | 250 | if (!css_tryget_online(&blkcg->css)) { |
20386ce0 | 251 | ret = -ENODEV; |
93e6d5d8 | 252 | goto err_free_blkg; |
15974993 | 253 | } |
cd1604fa | 254 | |
d708f0d5 JA |
255 | /* allocate */ |
256 | if (!new_blkg) { | |
257 | new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT | __GFP_NOWARN); | |
258 | if (unlikely(!new_blkg)) { | |
259 | ret = -ENOMEM; | |
8c911f3d | 260 | goto err_put_css; |
15974993 TH |
261 | } |
262 | } | |
d708f0d5 | 263 | blkg = new_blkg; |
cd1604fa | 264 | |
db613670 | 265 | /* link parent */ |
3c547865 TH |
266 | if (blkcg_parent(blkcg)) { |
267 | blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false); | |
268 | if (WARN_ON_ONCE(!blkg->parent)) { | |
20386ce0 | 269 | ret = -ENODEV; |
8c911f3d | 270 | goto err_put_css; |
3c547865 TH |
271 | } |
272 | blkg_get(blkg->parent); | |
273 | } | |
274 | ||
db613670 TH |
275 | /* invoke per-policy init */ |
276 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
277 | struct blkcg_policy *pol = blkcg_policy[i]; | |
278 | ||
279 | if (blkg->pd[i] && pol->pd_init_fn) | |
a9520cd6 | 280 | pol->pd_init_fn(blkg->pd[i]); |
db613670 TH |
281 | } |
282 | ||
283 | /* insert */ | |
cd1604fa | 284 | spin_lock(&blkcg->lock); |
a637120e TH |
285 | ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg); |
286 | if (likely(!ret)) { | |
287 | hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); | |
288 | list_add(&blkg->q_node, &q->blkg_list); | |
f427d909 TH |
289 | |
290 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
291 | struct blkcg_policy *pol = blkcg_policy[i]; | |
292 | ||
293 | if (blkg->pd[i] && pol->pd_online_fn) | |
a9520cd6 | 294 | pol->pd_online_fn(blkg->pd[i]); |
f427d909 | 295 | } |
a637120e | 296 | } |
f427d909 | 297 | blkg->online = true; |
cd1604fa | 298 | spin_unlock(&blkcg->lock); |
496fb780 | 299 | |
ec13b1d6 | 300 | if (!ret) |
a637120e | 301 | return blkg; |
15974993 | 302 | |
3c547865 TH |
303 | /* @blkg failed fully initialized, use the usual release path */ |
304 | blkg_put(blkg); | |
305 | return ERR_PTR(ret); | |
306 | ||
d708f0d5 | 307 | err_put_css: |
496fb780 | 308 | css_put(&blkcg->css); |
93e6d5d8 | 309 | err_free_blkg: |
d708f0d5 | 310 | blkg_free(new_blkg); |
93e6d5d8 | 311 | return ERR_PTR(ret); |
31e4c28d | 312 | } |
3c96cb32 | 313 | |
86cde6b6 | 314 | /** |
8c546287 | 315 | * blkg_lookup_create - lookup blkg, try to create one if not there |
86cde6b6 TH |
316 | * @blkcg: blkcg of interest |
317 | * @q: request_queue of interest | |
318 | * | |
319 | * Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to | |
3c547865 TH |
320 | * create one. blkg creation is performed recursively from blkcg_root such |
321 | * that all non-root blkg's have access to the parent blkg. This function | |
8c546287 | 322 | * should be called under RCU read lock and takes @q->queue_lock. |
86cde6b6 | 323 | * |
beea9da0 DZ |
324 | * Returns the blkg or the closest blkg if blkg_create() fails as it walks |
325 | * down from root. | |
86cde6b6 | 326 | */ |
8c546287 CH |
327 | static struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, |
328 | struct request_queue *q) | |
3c96cb32 | 329 | { |
86cde6b6 | 330 | struct blkcg_gq *blkg; |
8c546287 | 331 | unsigned long flags; |
86cde6b6 TH |
332 | |
333 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
86cde6b6 | 334 | |
8c546287 | 335 | blkg = blkg_lookup(blkcg, q); |
86cde6b6 TH |
336 | if (blkg) |
337 | return blkg; | |
338 | ||
8c546287 CH |
339 | spin_lock_irqsave(&q->queue_lock, flags); |
340 | blkg = __blkg_lookup(blkcg, q, true); | |
341 | if (blkg) | |
342 | goto found; | |
343 | ||
3c547865 TH |
344 | /* |
345 | * Create blkgs walking down from blkcg_root to @blkcg, so that all | |
beea9da0 DZ |
346 | * non-root blkgs have access to their parents. Returns the closest |
347 | * blkg to the intended blkg should blkg_create() fail. | |
3c547865 TH |
348 | */ |
349 | while (true) { | |
350 | struct blkcg *pos = blkcg; | |
351 | struct blkcg *parent = blkcg_parent(blkcg); | |
beea9da0 DZ |
352 | struct blkcg_gq *ret_blkg = q->root_blkg; |
353 | ||
354 | while (parent) { | |
355 | blkg = __blkg_lookup(parent, q, false); | |
356 | if (blkg) { | |
357 | /* remember closest blkg */ | |
358 | ret_blkg = blkg; | |
359 | break; | |
360 | } | |
3c547865 TH |
361 | pos = parent; |
362 | parent = blkcg_parent(parent); | |
363 | } | |
364 | ||
d708f0d5 | 365 | blkg = blkg_create(pos, q, NULL); |
8c546287 CH |
366 | if (IS_ERR(blkg)) { |
367 | blkg = ret_blkg; | |
368 | break; | |
369 | } | |
beea9da0 | 370 | if (pos == blkcg) |
8c546287 | 371 | break; |
b978962a DZ |
372 | } |
373 | ||
8c546287 CH |
374 | found: |
375 | spin_unlock_irqrestore(&q->queue_lock, flags); | |
b978962a DZ |
376 | return blkg; |
377 | } | |
378 | ||
3c798398 | 379 | static void blkg_destroy(struct blkcg_gq *blkg) |
03aa264a | 380 | { |
3c798398 | 381 | struct blkcg *blkcg = blkg->blkcg; |
6b065462 | 382 | int i; |
03aa264a | 383 | |
0d945c1f | 384 | lockdep_assert_held(&blkg->q->queue_lock); |
9f13ef67 | 385 | lockdep_assert_held(&blkcg->lock); |
03aa264a TH |
386 | |
387 | /* Something wrong if we are trying to remove same group twice */ | |
e8989fae | 388 | WARN_ON_ONCE(list_empty(&blkg->q_node)); |
9f13ef67 | 389 | WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node)); |
a637120e | 390 | |
6b065462 DZF |
391 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
392 | struct blkcg_policy *pol = blkcg_policy[i]; | |
393 | ||
394 | if (blkg->pd[i] && pol->pd_offline_fn) | |
395 | pol->pd_offline_fn(blkg->pd[i]); | |
396 | } | |
397 | ||
f427d909 TH |
398 | blkg->online = false; |
399 | ||
a637120e | 400 | radix_tree_delete(&blkcg->blkg_tree, blkg->q->id); |
e8989fae | 401 | list_del_init(&blkg->q_node); |
9f13ef67 | 402 | hlist_del_init_rcu(&blkg->blkcg_node); |
03aa264a | 403 | |
a637120e TH |
404 | /* |
405 | * Both setting lookup hint to and clearing it from @blkg are done | |
406 | * under queue_lock. If it's not pointing to @blkg now, it never | |
407 | * will. Hint assignment itself can race safely. | |
408 | */ | |
ec6c676a | 409 | if (rcu_access_pointer(blkcg->blkg_hint) == blkg) |
a637120e TH |
410 | rcu_assign_pointer(blkcg->blkg_hint, NULL); |
411 | ||
03aa264a TH |
412 | /* |
413 | * Put the reference taken at the time of creation so that when all | |
414 | * queues are gone, group can be destroyed. | |
415 | */ | |
7fcf2b03 | 416 | percpu_ref_kill(&blkg->refcnt); |
03aa264a TH |
417 | } |
418 | ||
9f13ef67 TH |
419 | /** |
420 | * blkg_destroy_all - destroy all blkgs associated with a request_queue | |
421 | * @q: request_queue of interest | |
9f13ef67 | 422 | * |
3c96cb32 | 423 | * Destroy all blkgs associated with @q. |
9f13ef67 | 424 | */ |
3c96cb32 | 425 | static void blkg_destroy_all(struct request_queue *q) |
72e06c25 | 426 | { |
3c798398 | 427 | struct blkcg_gq *blkg, *n; |
a731763f | 428 | int count = BLKG_DESTROY_BATCH_SIZE; |
72e06c25 | 429 | |
a731763f | 430 | restart: |
0d945c1f | 431 | spin_lock_irq(&q->queue_lock); |
9f13ef67 | 432 | list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { |
3c798398 | 433 | struct blkcg *blkcg = blkg->blkcg; |
72e06c25 | 434 | |
9f13ef67 TH |
435 | spin_lock(&blkcg->lock); |
436 | blkg_destroy(blkg); | |
437 | spin_unlock(&blkcg->lock); | |
a731763f YK |
438 | |
439 | /* | |
440 | * in order to avoid holding the spin lock for too long, release | |
441 | * it when a batch of blkgs are destroyed. | |
442 | */ | |
443 | if (!(--count)) { | |
444 | count = BLKG_DESTROY_BATCH_SIZE; | |
445 | spin_unlock_irq(&q->queue_lock); | |
446 | cond_resched(); | |
447 | goto restart; | |
448 | } | |
72e06c25 | 449 | } |
6fe810bd TH |
450 | |
451 | q->root_blkg = NULL; | |
0d945c1f | 452 | spin_unlock_irq(&q->queue_lock); |
72e06c25 TH |
453 | } |
454 | ||
182446d0 TH |
455 | static int blkcg_reset_stats(struct cgroup_subsys_state *css, |
456 | struct cftype *cftype, u64 val) | |
303a3acb | 457 | { |
182446d0 | 458 | struct blkcg *blkcg = css_to_blkcg(css); |
3c798398 | 459 | struct blkcg_gq *blkg; |
f7331648 | 460 | int i, cpu; |
303a3acb | 461 | |
838f13bf | 462 | mutex_lock(&blkcg_pol_mutex); |
303a3acb | 463 | spin_lock_irq(&blkcg->lock); |
997a026c TH |
464 | |
465 | /* | |
466 | * Note that stat reset is racy - it doesn't synchronize against | |
467 | * stat updates. This is a debug feature which shouldn't exist | |
468 | * anyway. If you get hit by a race, retry. | |
469 | */ | |
b67bfe0d | 470 | hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { |
f7331648 TH |
471 | for_each_possible_cpu(cpu) { |
472 | struct blkg_iostat_set *bis = | |
473 | per_cpu_ptr(blkg->iostat_cpu, cpu); | |
474 | memset(bis, 0, sizeof(*bis)); | |
475 | } | |
476 | memset(&blkg->iostat, 0, sizeof(blkg->iostat)); | |
77ea7338 | 477 | |
8bd435b3 | 478 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
3c798398 | 479 | struct blkcg_policy *pol = blkcg_policy[i]; |
549d3aa8 | 480 | |
a9520cd6 TH |
481 | if (blkg->pd[i] && pol->pd_reset_stats_fn) |
482 | pol->pd_reset_stats_fn(blkg->pd[i]); | |
bc0d6501 | 483 | } |
303a3acb | 484 | } |
f0bdc8cd | 485 | |
303a3acb | 486 | spin_unlock_irq(&blkcg->lock); |
bc0d6501 | 487 | mutex_unlock(&blkcg_pol_mutex); |
303a3acb DS |
488 | return 0; |
489 | } | |
490 | ||
dd165eb3 | 491 | const char *blkg_dev_name(struct blkcg_gq *blkg) |
303a3acb | 492 | { |
d152c682 | 493 | if (!blkg->q->disk || !blkg->q->disk->bdi->dev) |
edb0872f | 494 | return NULL; |
d152c682 | 495 | return bdi_dev_name(blkg->q->disk->bdi); |
303a3acb DS |
496 | } |
497 | ||
d3d32e69 TH |
498 | /** |
499 | * blkcg_print_blkgs - helper for printing per-blkg data | |
500 | * @sf: seq_file to print to | |
501 | * @blkcg: blkcg of interest | |
502 | * @prfill: fill function to print out a blkg | |
503 | * @pol: policy in question | |
504 | * @data: data to be passed to @prfill | |
505 | * @show_total: to print out sum of prfill return values or not | |
506 | * | |
507 | * This function invokes @prfill on each blkg of @blkcg if pd for the | |
508 | * policy specified by @pol exists. @prfill is invoked with @sf, the | |
810ecfa7 TH |
509 | * policy data and @data and the matching queue lock held. If @show_total |
510 | * is %true, the sum of the return values from @prfill is printed with | |
511 | * "Total" label at the end. | |
d3d32e69 TH |
512 | * |
513 | * This is to be used to construct print functions for | |
514 | * cftype->read_seq_string method. | |
515 | */ | |
3c798398 | 516 | void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg, |
f95a04af TH |
517 | u64 (*prfill)(struct seq_file *, |
518 | struct blkg_policy_data *, int), | |
3c798398 | 519 | const struct blkcg_policy *pol, int data, |
ec399347 | 520 | bool show_total) |
5624a4e4 | 521 | { |
3c798398 | 522 | struct blkcg_gq *blkg; |
d3d32e69 | 523 | u64 total = 0; |
5624a4e4 | 524 | |
810ecfa7 | 525 | rcu_read_lock(); |
ee89f812 | 526 | hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { |
0d945c1f | 527 | spin_lock_irq(&blkg->q->queue_lock); |
a2b1693b | 528 | if (blkcg_policy_enabled(blkg->q, pol)) |
f95a04af | 529 | total += prfill(sf, blkg->pd[pol->plid], data); |
0d945c1f | 530 | spin_unlock_irq(&blkg->q->queue_lock); |
810ecfa7 TH |
531 | } |
532 | rcu_read_unlock(); | |
d3d32e69 TH |
533 | |
534 | if (show_total) | |
535 | seq_printf(sf, "Total %llu\n", (unsigned long long)total); | |
536 | } | |
829fdb50 | 537 | EXPORT_SYMBOL_GPL(blkcg_print_blkgs); |
d3d32e69 TH |
538 | |
539 | /** | |
540 | * __blkg_prfill_u64 - prfill helper for a single u64 value | |
541 | * @sf: seq_file to print to | |
f95a04af | 542 | * @pd: policy private data of interest |
d3d32e69 TH |
543 | * @v: value to print |
544 | * | |
f95a04af | 545 | * Print @v to @sf for the device assocaited with @pd. |
d3d32e69 | 546 | */ |
f95a04af | 547 | u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v) |
d3d32e69 | 548 | { |
f95a04af | 549 | const char *dname = blkg_dev_name(pd->blkg); |
d3d32e69 TH |
550 | |
551 | if (!dname) | |
552 | return 0; | |
553 | ||
554 | seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v); | |
555 | return v; | |
556 | } | |
829fdb50 | 557 | EXPORT_SYMBOL_GPL(__blkg_prfill_u64); |
d3d32e69 | 558 | |
457e490f TE |
559 | /* Performs queue bypass and policy enabled checks then looks up blkg. */ |
560 | static struct blkcg_gq *blkg_lookup_check(struct blkcg *blkcg, | |
561 | const struct blkcg_policy *pol, | |
562 | struct request_queue *q) | |
563 | { | |
564 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
0d945c1f | 565 | lockdep_assert_held(&q->queue_lock); |
457e490f TE |
566 | |
567 | if (!blkcg_policy_enabled(q, pol)) | |
568 | return ERR_PTR(-EOPNOTSUPP); | |
457e490f TE |
569 | return __blkg_lookup(blkcg, q, true /* update_hint */); |
570 | } | |
571 | ||
015d254c | 572 | /** |
22ae8ce8 | 573 | * blkcg_conf_open_bdev - parse and open bdev for per-blkg config update |
015d254c TH |
574 | * @inputp: input string pointer |
575 | * | |
576 | * Parse the device node prefix part, MAJ:MIN, of per-blkg config update | |
22ae8ce8 | 577 | * from @input and get and return the matching bdev. *@inputp is |
015d254c TH |
578 | * updated to point past the device node prefix. Returns an ERR_PTR() |
579 | * value on error. | |
580 | * | |
581 | * Use this function iff blkg_conf_prep() can't be used for some reason. | |
582 | */ | |
22ae8ce8 | 583 | struct block_device *blkcg_conf_open_bdev(char **inputp) |
015d254c TH |
584 | { |
585 | char *input = *inputp; | |
586 | unsigned int major, minor; | |
22ae8ce8 CH |
587 | struct block_device *bdev; |
588 | int key_len; | |
015d254c TH |
589 | |
590 | if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2) | |
591 | return ERR_PTR(-EINVAL); | |
592 | ||
593 | input += key_len; | |
594 | if (!isspace(*input)) | |
595 | return ERR_PTR(-EINVAL); | |
596 | input = skip_spaces(input); | |
597 | ||
22ae8ce8 CH |
598 | bdev = blkdev_get_no_open(MKDEV(major, minor)); |
599 | if (!bdev) | |
015d254c | 600 | return ERR_PTR(-ENODEV); |
22ae8ce8 CH |
601 | if (bdev_is_partition(bdev)) { |
602 | blkdev_put_no_open(bdev); | |
015d254c TH |
603 | return ERR_PTR(-ENODEV); |
604 | } | |
605 | ||
606 | *inputp = input; | |
22ae8ce8 | 607 | return bdev; |
015d254c TH |
608 | } |
609 | ||
3a8b31d3 TH |
610 | /** |
611 | * blkg_conf_prep - parse and prepare for per-blkg config update | |
612 | * @blkcg: target block cgroup | |
da8b0662 | 613 | * @pol: target policy |
3a8b31d3 TH |
614 | * @input: input string |
615 | * @ctx: blkg_conf_ctx to be filled | |
616 | * | |
617 | * Parse per-blkg config update from @input and initialize @ctx with the | |
36aa9e5f TH |
618 | * result. @ctx->blkg points to the blkg to be updated and @ctx->body the |
619 | * part of @input following MAJ:MIN. This function returns with RCU read | |
620 | * lock and queue lock held and must be paired with blkg_conf_finish(). | |
3a8b31d3 | 621 | */ |
3c798398 | 622 | int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, |
36aa9e5f | 623 | char *input, struct blkg_conf_ctx *ctx) |
ed6cddef | 624 | __acquires(rcu) __acquires(&bdev->bd_queue->queue_lock) |
34d0f179 | 625 | { |
22ae8ce8 | 626 | struct block_device *bdev; |
457e490f | 627 | struct request_queue *q; |
3c798398 | 628 | struct blkcg_gq *blkg; |
015d254c | 629 | int ret; |
36aa9e5f | 630 | |
22ae8ce8 CH |
631 | bdev = blkcg_conf_open_bdev(&input); |
632 | if (IS_ERR(bdev)) | |
633 | return PTR_ERR(bdev); | |
e56da7e2 | 634 | |
ed6cddef | 635 | q = bdev_get_queue(bdev); |
da8b0662 | 636 | |
0c9d338c YK |
637 | /* |
638 | * blkcg_deactivate_policy() requires queue to be frozen, we can grab | |
639 | * q_usage_counter to prevent concurrent with blkcg_deactivate_policy(). | |
640 | */ | |
641 | ret = blk_queue_enter(q, 0); | |
642 | if (ret) | |
15c30104 | 643 | goto fail; |
0c9d338c | 644 | |
457e490f | 645 | rcu_read_lock(); |
0d945c1f | 646 | spin_lock_irq(&q->queue_lock); |
e56da7e2 | 647 | |
457e490f | 648 | blkg = blkg_lookup_check(blkcg, pol, q); |
4bfd482e TH |
649 | if (IS_ERR(blkg)) { |
650 | ret = PTR_ERR(blkg); | |
457e490f TE |
651 | goto fail_unlock; |
652 | } | |
653 | ||
654 | if (blkg) | |
655 | goto success; | |
656 | ||
657 | /* | |
658 | * Create blkgs walking down from blkcg_root to @blkcg, so that all | |
659 | * non-root blkgs have access to their parents. | |
660 | */ | |
661 | while (true) { | |
662 | struct blkcg *pos = blkcg; | |
663 | struct blkcg *parent; | |
664 | struct blkcg_gq *new_blkg; | |
665 | ||
666 | parent = blkcg_parent(blkcg); | |
667 | while (parent && !__blkg_lookup(parent, q, false)) { | |
668 | pos = parent; | |
669 | parent = blkcg_parent(parent); | |
670 | } | |
671 | ||
672 | /* Drop locks to do new blkg allocation with GFP_KERNEL. */ | |
0d945c1f | 673 | spin_unlock_irq(&q->queue_lock); |
3a8b31d3 | 674 | rcu_read_unlock(); |
457e490f TE |
675 | |
676 | new_blkg = blkg_alloc(pos, q, GFP_KERNEL); | |
677 | if (unlikely(!new_blkg)) { | |
678 | ret = -ENOMEM; | |
15c30104 | 679 | goto fail_exit_queue; |
7702e8f4 | 680 | } |
3a8b31d3 | 681 | |
f255c19b GKB |
682 | if (radix_tree_preload(GFP_KERNEL)) { |
683 | blkg_free(new_blkg); | |
684 | ret = -ENOMEM; | |
15c30104 | 685 | goto fail_exit_queue; |
f255c19b GKB |
686 | } |
687 | ||
457e490f | 688 | rcu_read_lock(); |
0d945c1f | 689 | spin_lock_irq(&q->queue_lock); |
457e490f TE |
690 | |
691 | blkg = blkg_lookup_check(pos, pol, q); | |
692 | if (IS_ERR(blkg)) { | |
693 | ret = PTR_ERR(blkg); | |
52abfcbd | 694 | blkg_free(new_blkg); |
f255c19b | 695 | goto fail_preloaded; |
457e490f TE |
696 | } |
697 | ||
698 | if (blkg) { | |
699 | blkg_free(new_blkg); | |
700 | } else { | |
701 | blkg = blkg_create(pos, q, new_blkg); | |
98d669b4 | 702 | if (IS_ERR(blkg)) { |
457e490f | 703 | ret = PTR_ERR(blkg); |
f255c19b | 704 | goto fail_preloaded; |
457e490f TE |
705 | } |
706 | } | |
707 | ||
f255c19b GKB |
708 | radix_tree_preload_end(); |
709 | ||
457e490f TE |
710 | if (pos == blkcg) |
711 | goto success; | |
712 | } | |
713 | success: | |
0c9d338c | 714 | blk_queue_exit(q); |
22ae8ce8 | 715 | ctx->bdev = bdev; |
3a8b31d3 | 716 | ctx->blkg = blkg; |
015d254c | 717 | ctx->body = input; |
726fa694 | 718 | return 0; |
457e490f | 719 | |
f255c19b GKB |
720 | fail_preloaded: |
721 | radix_tree_preload_end(); | |
457e490f | 722 | fail_unlock: |
0d945c1f | 723 | spin_unlock_irq(&q->queue_lock); |
457e490f | 724 | rcu_read_unlock(); |
15c30104 YK |
725 | fail_exit_queue: |
726 | blk_queue_exit(q); | |
457e490f | 727 | fail: |
22ae8ce8 | 728 | blkdev_put_no_open(bdev); |
457e490f TE |
729 | /* |
730 | * If queue was bypassing, we should retry. Do so after a | |
731 | * short msleep(). It isn't strictly necessary but queue | |
732 | * can be bypassing for some time and it's always nice to | |
733 | * avoid busy looping. | |
734 | */ | |
735 | if (ret == -EBUSY) { | |
736 | msleep(10); | |
737 | ret = restart_syscall(); | |
738 | } | |
739 | return ret; | |
34d0f179 | 740 | } |
89f3b6d6 | 741 | EXPORT_SYMBOL_GPL(blkg_conf_prep); |
34d0f179 | 742 | |
3a8b31d3 TH |
743 | /** |
744 | * blkg_conf_finish - finish up per-blkg config update | |
745 | * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep() | |
746 | * | |
747 | * Finish up after per-blkg config update. This function must be paired | |
748 | * with blkg_conf_prep(). | |
749 | */ | |
829fdb50 | 750 | void blkg_conf_finish(struct blkg_conf_ctx *ctx) |
ed6cddef | 751 | __releases(&ctx->bdev->bd_queue->queue_lock) __releases(rcu) |
34d0f179 | 752 | { |
ed6cddef | 753 | spin_unlock_irq(&bdev_get_queue(ctx->bdev)->queue_lock); |
3a8b31d3 | 754 | rcu_read_unlock(); |
22ae8ce8 | 755 | blkdev_put_no_open(ctx->bdev); |
34d0f179 | 756 | } |
89f3b6d6 | 757 | EXPORT_SYMBOL_GPL(blkg_conf_finish); |
34d0f179 | 758 | |
cd1fc4b9 BB |
759 | static void blkg_iostat_set(struct blkg_iostat *dst, struct blkg_iostat *src) |
760 | { | |
761 | int i; | |
762 | ||
763 | for (i = 0; i < BLKG_IOSTAT_NR; i++) { | |
764 | dst->bytes[i] = src->bytes[i]; | |
765 | dst->ios[i] = src->ios[i]; | |
766 | } | |
767 | } | |
768 | ||
769 | static void blkg_iostat_add(struct blkg_iostat *dst, struct blkg_iostat *src) | |
770 | { | |
771 | int i; | |
772 | ||
773 | for (i = 0; i < BLKG_IOSTAT_NR; i++) { | |
774 | dst->bytes[i] += src->bytes[i]; | |
775 | dst->ios[i] += src->ios[i]; | |
776 | } | |
777 | } | |
778 | ||
779 | static void blkg_iostat_sub(struct blkg_iostat *dst, struct blkg_iostat *src) | |
780 | { | |
781 | int i; | |
782 | ||
783 | for (i = 0; i < BLKG_IOSTAT_NR; i++) { | |
784 | dst->bytes[i] -= src->bytes[i]; | |
785 | dst->ios[i] -= src->ios[i]; | |
786 | } | |
787 | } | |
788 | ||
789 | static void blkcg_rstat_flush(struct cgroup_subsys_state *css, int cpu) | |
790 | { | |
791 | struct blkcg *blkcg = css_to_blkcg(css); | |
792 | struct blkcg_gq *blkg; | |
793 | ||
dc26532a JW |
794 | /* Root-level stats are sourced from system-wide IO stats */ |
795 | if (!cgroup_parent(css->cgroup)) | |
796 | return; | |
797 | ||
cd1fc4b9 BB |
798 | rcu_read_lock(); |
799 | ||
800 | hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { | |
801 | struct blkcg_gq *parent = blkg->parent; | |
802 | struct blkg_iostat_set *bisc = per_cpu_ptr(blkg->iostat_cpu, cpu); | |
803 | struct blkg_iostat cur, delta; | |
c3df5fb5 | 804 | unsigned long flags; |
cd1fc4b9 BB |
805 | unsigned int seq; |
806 | ||
807 | /* fetch the current per-cpu values */ | |
808 | do { | |
809 | seq = u64_stats_fetch_begin(&bisc->sync); | |
810 | blkg_iostat_set(&cur, &bisc->cur); | |
811 | } while (u64_stats_fetch_retry(&bisc->sync, seq)); | |
812 | ||
813 | /* propagate percpu delta to global */ | |
c3df5fb5 | 814 | flags = u64_stats_update_begin_irqsave(&blkg->iostat.sync); |
cd1fc4b9 BB |
815 | blkg_iostat_set(&delta, &cur); |
816 | blkg_iostat_sub(&delta, &bisc->last); | |
817 | blkg_iostat_add(&blkg->iostat.cur, &delta); | |
818 | blkg_iostat_add(&bisc->last, &delta); | |
c3df5fb5 | 819 | u64_stats_update_end_irqrestore(&blkg->iostat.sync, flags); |
cd1fc4b9 | 820 | |
dc26532a JW |
821 | /* propagate global delta to parent (unless that's root) */ |
822 | if (parent && parent->parent) { | |
c3df5fb5 | 823 | flags = u64_stats_update_begin_irqsave(&parent->iostat.sync); |
cd1fc4b9 BB |
824 | blkg_iostat_set(&delta, &blkg->iostat.cur); |
825 | blkg_iostat_sub(&delta, &blkg->iostat.last); | |
826 | blkg_iostat_add(&parent->iostat.cur, &delta); | |
827 | blkg_iostat_add(&blkg->iostat.last, &delta); | |
c3df5fb5 | 828 | u64_stats_update_end_irqrestore(&parent->iostat.sync, flags); |
cd1fc4b9 BB |
829 | } |
830 | } | |
831 | ||
832 | rcu_read_unlock(); | |
833 | } | |
834 | ||
ef45fe47 | 835 | /* |
dc26532a JW |
836 | * We source root cgroup stats from the system-wide stats to avoid |
837 | * tracking the same information twice and incurring overhead when no | |
838 | * cgroups are defined. For that reason, cgroup_rstat_flush in | |
839 | * blkcg_print_stat does not actually fill out the iostat in the root | |
840 | * cgroup's blkcg_gq. | |
ef45fe47 BB |
841 | * |
842 | * However, we would like to re-use the printing code between the root and | |
843 | * non-root cgroups to the extent possible. For that reason, we simulate | |
844 | * flushing the root cgroup's stats by explicitly filling in the iostat | |
845 | * with disk level statistics. | |
846 | */ | |
847 | static void blkcg_fill_root_iostats(void) | |
848 | { | |
849 | struct class_dev_iter iter; | |
850 | struct device *dev; | |
851 | ||
852 | class_dev_iter_init(&iter, &block_class, NULL, &disk_type); | |
853 | while ((dev = class_dev_iter_next(&iter))) { | |
0d02129e CH |
854 | struct block_device *bdev = dev_to_bdev(dev); |
855 | struct blkcg_gq *blkg = | |
ed6cddef | 856 | blk_queue_root_blkg(bdev_get_queue(bdev)); |
ef45fe47 BB |
857 | struct blkg_iostat tmp; |
858 | int cpu; | |
859 | ||
860 | memset(&tmp, 0, sizeof(tmp)); | |
861 | for_each_possible_cpu(cpu) { | |
862 | struct disk_stats *cpu_dkstats; | |
c3df5fb5 | 863 | unsigned long flags; |
ef45fe47 | 864 | |
0d02129e | 865 | cpu_dkstats = per_cpu_ptr(bdev->bd_stats, cpu); |
ef45fe47 BB |
866 | tmp.ios[BLKG_IOSTAT_READ] += |
867 | cpu_dkstats->ios[STAT_READ]; | |
868 | tmp.ios[BLKG_IOSTAT_WRITE] += | |
869 | cpu_dkstats->ios[STAT_WRITE]; | |
870 | tmp.ios[BLKG_IOSTAT_DISCARD] += | |
871 | cpu_dkstats->ios[STAT_DISCARD]; | |
872 | // convert sectors to bytes | |
873 | tmp.bytes[BLKG_IOSTAT_READ] += | |
874 | cpu_dkstats->sectors[STAT_READ] << 9; | |
875 | tmp.bytes[BLKG_IOSTAT_WRITE] += | |
876 | cpu_dkstats->sectors[STAT_WRITE] << 9; | |
877 | tmp.bytes[BLKG_IOSTAT_DISCARD] += | |
878 | cpu_dkstats->sectors[STAT_DISCARD] << 9; | |
879 | ||
c3df5fb5 | 880 | flags = u64_stats_update_begin_irqsave(&blkg->iostat.sync); |
ef45fe47 | 881 | blkg_iostat_set(&blkg->iostat.cur, &tmp); |
c3df5fb5 | 882 | u64_stats_update_end_irqrestore(&blkg->iostat.sync, flags); |
ef45fe47 BB |
883 | } |
884 | } | |
885 | } | |
886 | ||
49cb5168 | 887 | static void blkcg_print_one_stat(struct blkcg_gq *blkg, struct seq_file *s) |
2ee867dc | 888 | { |
49cb5168 CH |
889 | struct blkg_iostat_set *bis = &blkg->iostat; |
890 | u64 rbytes, wbytes, rios, wios, dbytes, dios; | |
891 | bool has_stats = false; | |
892 | const char *dname; | |
893 | unsigned seq; | |
49cb5168 | 894 | int i; |
ef45fe47 | 895 | |
49cb5168 CH |
896 | if (!blkg->online) |
897 | return; | |
2ee867dc | 898 | |
49cb5168 CH |
899 | dname = blkg_dev_name(blkg); |
900 | if (!dname) | |
901 | return; | |
2ee867dc | 902 | |
252c651a | 903 | seq_printf(s, "%s ", dname); |
b0814361 | 904 | |
49cb5168 CH |
905 | do { |
906 | seq = u64_stats_fetch_begin(&bis->sync); | |
b0814361 | 907 | |
49cb5168 CH |
908 | rbytes = bis->cur.bytes[BLKG_IOSTAT_READ]; |
909 | wbytes = bis->cur.bytes[BLKG_IOSTAT_WRITE]; | |
910 | dbytes = bis->cur.bytes[BLKG_IOSTAT_DISCARD]; | |
911 | rios = bis->cur.ios[BLKG_IOSTAT_READ]; | |
912 | wios = bis->cur.ios[BLKG_IOSTAT_WRITE]; | |
913 | dios = bis->cur.ios[BLKG_IOSTAT_DISCARD]; | |
914 | } while (u64_stats_fetch_retry(&bis->sync, seq)); | |
2ee867dc | 915 | |
49cb5168 CH |
916 | if (rbytes || wbytes || rios || wios) { |
917 | has_stats = true; | |
252c651a | 918 | seq_printf(s, "rbytes=%llu wbytes=%llu rios=%llu wios=%llu dbytes=%llu dios=%llu", |
49cb5168 CH |
919 | rbytes, wbytes, rios, wios, |
920 | dbytes, dios); | |
921 | } | |
903d23f0 | 922 | |
49cb5168 CH |
923 | if (blkcg_debug_stats && atomic_read(&blkg->use_delay)) { |
924 | has_stats = true; | |
252c651a | 925 | seq_printf(s, " use_delay=%d delay_nsec=%llu", |
49cb5168 CH |
926 | atomic_read(&blkg->use_delay), |
927 | atomic64_read(&blkg->delay_nsec)); | |
928 | } | |
2ee867dc | 929 | |
49cb5168 CH |
930 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
931 | struct blkcg_policy *pol = blkcg_policy[i]; | |
2ee867dc | 932 | |
49cb5168 CH |
933 | if (!blkg->pd[i] || !pol->pd_stat_fn) |
934 | continue; | |
903d23f0 | 935 | |
252c651a | 936 | if (pol->pd_stat_fn(blkg->pd[i], s)) |
d09d8df3 | 937 | has_stats = true; |
49cb5168 | 938 | } |
d09d8df3 | 939 | |
252c651a CH |
940 | if (has_stats) |
941 | seq_printf(s, "\n"); | |
49cb5168 | 942 | } |
903d23f0 | 943 | |
49cb5168 CH |
944 | static int blkcg_print_stat(struct seq_file *sf, void *v) |
945 | { | |
946 | struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); | |
947 | struct blkcg_gq *blkg; | |
903d23f0 | 948 | |
49cb5168 CH |
949 | if (!seq_css(sf)->parent) |
950 | blkcg_fill_root_iostats(); | |
951 | else | |
952 | cgroup_rstat_flush(blkcg->css.cgroup); | |
07b0fdec | 953 | |
49cb5168 CH |
954 | rcu_read_lock(); |
955 | hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { | |
956 | spin_lock_irq(&blkg->q->queue_lock); | |
957 | blkcg_print_one_stat(blkg, sf); | |
b0814361 | 958 | spin_unlock_irq(&blkg->q->queue_lock); |
2ee867dc | 959 | } |
2ee867dc TH |
960 | rcu_read_unlock(); |
961 | return 0; | |
962 | } | |
963 | ||
e1f3b941 | 964 | static struct cftype blkcg_files[] = { |
2ee867dc TH |
965 | { |
966 | .name = "stat", | |
967 | .seq_show = blkcg_print_stat, | |
968 | }, | |
969 | { } /* terminate */ | |
970 | }; | |
971 | ||
e1f3b941 | 972 | static struct cftype blkcg_legacy_files[] = { |
84c124da DS |
973 | { |
974 | .name = "reset_stats", | |
3c798398 | 975 | .write_u64 = blkcg_reset_stats, |
22084190 | 976 | }, |
4baf6e33 | 977 | { } /* terminate */ |
31e4c28d VG |
978 | }; |
979 | ||
59b57717 DZF |
980 | /* |
981 | * blkcg destruction is a three-stage process. | |
982 | * | |
983 | * 1. Destruction starts. The blkcg_css_offline() callback is invoked | |
984 | * which offlines writeback. Here we tie the next stage of blkg destruction | |
985 | * to the completion of writeback associated with the blkcg. This lets us | |
986 | * avoid punting potentially large amounts of outstanding writeback to root | |
987 | * while maintaining any ongoing policies. The next stage is triggered when | |
988 | * the nr_cgwbs count goes to zero. | |
989 | * | |
990 | * 2. When the nr_cgwbs count goes to zero, blkcg_destroy_blkgs() is called | |
991 | * and handles the destruction of blkgs. Here the css reference held by | |
992 | * the blkg is put back eventually allowing blkcg_css_free() to be called. | |
993 | * This work may occur in cgwb_release_workfn() on the cgwb_release | |
994 | * workqueue. Any submitted ios that fail to get the blkg ref will be | |
995 | * punted to the root_blkg. | |
996 | * | |
997 | * 3. Once the blkcg ref count goes to zero, blkcg_css_free() is called. | |
998 | * This finally frees the blkcg. | |
999 | */ | |
1000 | ||
9f13ef67 | 1001 | /** |
92fb9748 | 1002 | * blkcg_css_offline - cgroup css_offline callback |
eb95419b | 1003 | * @css: css of interest |
9f13ef67 | 1004 | * |
59b57717 DZF |
1005 | * This function is called when @css is about to go away. Here the cgwbs are |
1006 | * offlined first and only once writeback associated with the blkcg has | |
1007 | * finished do we start step 2 (see above). | |
9f13ef67 | 1008 | */ |
eb95419b | 1009 | static void blkcg_css_offline(struct cgroup_subsys_state *css) |
31e4c28d | 1010 | { |
eb95419b | 1011 | struct blkcg *blkcg = css_to_blkcg(css); |
b1c35769 | 1012 | |
59b57717 DZF |
1013 | /* this prevents anyone from attaching or migrating to this blkcg */ |
1014 | wb_blkcg_offline(blkcg); | |
1015 | ||
d866dbf6 TH |
1016 | /* put the base online pin allowing step 2 to be triggered */ |
1017 | blkcg_unpin_online(blkcg); | |
59b57717 DZF |
1018 | } |
1019 | ||
1020 | /** | |
1021 | * blkcg_destroy_blkgs - responsible for shooting down blkgs | |
1022 | * @blkcg: blkcg of interest | |
1023 | * | |
1024 | * blkgs should be removed while holding both q and blkcg locks. As blkcg lock | |
1025 | * is nested inside q lock, this function performs reverse double lock dancing. | |
1026 | * Destroying the blkgs releases the reference held on the blkcg's css allowing | |
1027 | * blkcg_css_free to eventually be called. | |
1028 | * | |
1029 | * This is the blkcg counterpart of ioc_release_fn(). | |
1030 | */ | |
1031 | void blkcg_destroy_blkgs(struct blkcg *blkcg) | |
1032 | { | |
6c635cae BW |
1033 | might_sleep(); |
1034 | ||
9f13ef67 | 1035 | spin_lock_irq(&blkcg->lock); |
7ee9c562 | 1036 | |
4c699480 JQ |
1037 | while (!hlist_empty(&blkcg->blkg_list)) { |
1038 | struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first, | |
6b065462 | 1039 | struct blkcg_gq, blkcg_node); |
4c699480 JQ |
1040 | struct request_queue *q = blkg->q; |
1041 | ||
6c635cae BW |
1042 | if (need_resched() || !spin_trylock(&q->queue_lock)) { |
1043 | /* | |
1044 | * Given that the system can accumulate a huge number | |
1045 | * of blkgs in pathological cases, check to see if we | |
1046 | * need to rescheduling to avoid softlockup. | |
1047 | */ | |
4c699480 | 1048 | spin_unlock_irq(&blkcg->lock); |
6c635cae | 1049 | cond_resched(); |
4c699480 | 1050 | spin_lock_irq(&blkcg->lock); |
6c635cae | 1051 | continue; |
4c699480 | 1052 | } |
6c635cae BW |
1053 | |
1054 | blkg_destroy(blkg); | |
1055 | spin_unlock(&q->queue_lock); | |
4c699480 | 1056 | } |
6b065462 | 1057 | |
4c699480 JQ |
1058 | spin_unlock_irq(&blkcg->lock); |
1059 | } | |
1060 | ||
eb95419b | 1061 | static void blkcg_css_free(struct cgroup_subsys_state *css) |
7ee9c562 | 1062 | { |
eb95419b | 1063 | struct blkcg *blkcg = css_to_blkcg(css); |
bc915e61 | 1064 | int i; |
7ee9c562 | 1065 | |
7876f930 | 1066 | mutex_lock(&blkcg_pol_mutex); |
e4a9bde9 | 1067 | |
7876f930 | 1068 | list_del(&blkcg->all_blkcgs_node); |
7876f930 | 1069 | |
bc915e61 | 1070 | for (i = 0; i < BLKCG_MAX_POLS; i++) |
e4a9bde9 TH |
1071 | if (blkcg->cpd[i]) |
1072 | blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]); | |
1073 | ||
1074 | mutex_unlock(&blkcg_pol_mutex); | |
1075 | ||
bc915e61 | 1076 | kfree(blkcg); |
31e4c28d VG |
1077 | } |
1078 | ||
eb95419b TH |
1079 | static struct cgroup_subsys_state * |
1080 | blkcg_css_alloc(struct cgroup_subsys_state *parent_css) | |
31e4c28d | 1081 | { |
3c798398 | 1082 | struct blkcg *blkcg; |
e48453c3 AA |
1083 | struct cgroup_subsys_state *ret; |
1084 | int i; | |
31e4c28d | 1085 | |
7876f930 TH |
1086 | mutex_lock(&blkcg_pol_mutex); |
1087 | ||
eb95419b | 1088 | if (!parent_css) { |
3c798398 | 1089 | blkcg = &blkcg_root; |
bc915e61 TH |
1090 | } else { |
1091 | blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); | |
1092 | if (!blkcg) { | |
1093 | ret = ERR_PTR(-ENOMEM); | |
4c18c9e9 | 1094 | goto unlock; |
bc915e61 | 1095 | } |
e48453c3 AA |
1096 | } |
1097 | ||
1098 | for (i = 0; i < BLKCG_MAX_POLS ; i++) { | |
1099 | struct blkcg_policy *pol = blkcg_policy[i]; | |
1100 | struct blkcg_policy_data *cpd; | |
1101 | ||
1102 | /* | |
1103 | * If the policy hasn't been attached yet, wait for it | |
1104 | * to be attached before doing anything else. Otherwise, | |
1105 | * check if the policy requires any specific per-cgroup | |
1106 | * data: if it does, allocate and initialize it. | |
1107 | */ | |
e4a9bde9 | 1108 | if (!pol || !pol->cpd_alloc_fn) |
e48453c3 AA |
1109 | continue; |
1110 | ||
e4a9bde9 | 1111 | cpd = pol->cpd_alloc_fn(GFP_KERNEL); |
e48453c3 AA |
1112 | if (!cpd) { |
1113 | ret = ERR_PTR(-ENOMEM); | |
1114 | goto free_pd_blkcg; | |
1115 | } | |
81437648 TH |
1116 | blkcg->cpd[i] = cpd; |
1117 | cpd->blkcg = blkcg; | |
e48453c3 | 1118 | cpd->plid = i; |
e4a9bde9 TH |
1119 | if (pol->cpd_init_fn) |
1120 | pol->cpd_init_fn(cpd); | |
e48453c3 | 1121 | } |
31e4c28d | 1122 | |
31e4c28d | 1123 | spin_lock_init(&blkcg->lock); |
d866dbf6 | 1124 | refcount_set(&blkcg->online_pin, 1); |
e00f4f4d | 1125 | INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT | __GFP_NOWARN); |
31e4c28d | 1126 | INIT_HLIST_HEAD(&blkcg->blkg_list); |
52ebea74 TH |
1127 | #ifdef CONFIG_CGROUP_WRITEBACK |
1128 | INIT_LIST_HEAD(&blkcg->cgwb_list); | |
1129 | #endif | |
7876f930 TH |
1130 | list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs); |
1131 | ||
1132 | mutex_unlock(&blkcg_pol_mutex); | |
31e4c28d | 1133 | return &blkcg->css; |
e48453c3 AA |
1134 | |
1135 | free_pd_blkcg: | |
1136 | for (i--; i >= 0; i--) | |
e4a9bde9 TH |
1137 | if (blkcg->cpd[i]) |
1138 | blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]); | |
4c18c9e9 | 1139 | |
1140 | if (blkcg != &blkcg_root) | |
1141 | kfree(blkcg); | |
1142 | unlock: | |
7876f930 | 1143 | mutex_unlock(&blkcg_pol_mutex); |
e48453c3 | 1144 | return ret; |
31e4c28d VG |
1145 | } |
1146 | ||
4308a434 TH |
1147 | static int blkcg_css_online(struct cgroup_subsys_state *css) |
1148 | { | |
1149 | struct blkcg *blkcg = css_to_blkcg(css); | |
1150 | struct blkcg *parent = blkcg_parent(blkcg); | |
1151 | ||
1152 | /* | |
1153 | * blkcg_pin_online() is used to delay blkcg offline so that blkgs | |
1154 | * don't go offline while cgwbs are still active on them. Pin the | |
1155 | * parent so that offline always happens towards the root. | |
1156 | */ | |
1157 | if (parent) | |
1158 | blkcg_pin_online(parent); | |
1159 | return 0; | |
1160 | } | |
1161 | ||
5efd6113 TH |
1162 | /** |
1163 | * blkcg_init_queue - initialize blkcg part of request queue | |
1164 | * @q: request_queue to initialize | |
1165 | * | |
c62b37d9 | 1166 | * Called from blk_alloc_queue(). Responsible for initializing blkcg |
5efd6113 TH |
1167 | * part of new request_queue @q. |
1168 | * | |
1169 | * RETURNS: | |
1170 | * 0 on success, -errno on failure. | |
1171 | */ | |
1172 | int blkcg_init_queue(struct request_queue *q) | |
1173 | { | |
d708f0d5 JA |
1174 | struct blkcg_gq *new_blkg, *blkg; |
1175 | bool preloaded; | |
ec13b1d6 TH |
1176 | int ret; |
1177 | ||
d708f0d5 JA |
1178 | new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL); |
1179 | if (!new_blkg) | |
1180 | return -ENOMEM; | |
1181 | ||
1182 | preloaded = !radix_tree_preload(GFP_KERNEL); | |
1183 | ||
bea54883 | 1184 | /* Make sure the root blkg exists. */ |
ec13b1d6 | 1185 | rcu_read_lock(); |
0d945c1f | 1186 | spin_lock_irq(&q->queue_lock); |
d708f0d5 | 1187 | blkg = blkg_create(&blkcg_root, q, new_blkg); |
901932a3 JB |
1188 | if (IS_ERR(blkg)) |
1189 | goto err_unlock; | |
1190 | q->root_blkg = blkg; | |
0d945c1f | 1191 | spin_unlock_irq(&q->queue_lock); |
ec13b1d6 TH |
1192 | rcu_read_unlock(); |
1193 | ||
d708f0d5 JA |
1194 | if (preloaded) |
1195 | radix_tree_preload_end(); | |
1196 | ||
556910e3 BVA |
1197 | ret = blk_ioprio_init(q); |
1198 | if (ret) | |
1199 | goto err_destroy_all; | |
1200 | ||
19688d7f BVA |
1201 | ret = blk_throtl_init(q); |
1202 | if (ret) | |
04be60b5 | 1203 | goto err_destroy_all; |
19688d7f | 1204 | |
6f5ddde4 YX |
1205 | ret = blk_iolatency_init(q); |
1206 | if (ret) { | |
1207 | blk_throtl_exit(q); | |
1208 | goto err_destroy_all; | |
1209 | } | |
1210 | ||
04be60b5 | 1211 | return 0; |
901932a3 | 1212 | |
04be60b5 | 1213 | err_destroy_all: |
04be60b5 | 1214 | blkg_destroy_all(q); |
04be60b5 | 1215 | return ret; |
901932a3 | 1216 | err_unlock: |
0d945c1f | 1217 | spin_unlock_irq(&q->queue_lock); |
901932a3 JB |
1218 | rcu_read_unlock(); |
1219 | if (preloaded) | |
1220 | radix_tree_preload_end(); | |
1221 | return PTR_ERR(blkg); | |
5efd6113 TH |
1222 | } |
1223 | ||
5efd6113 TH |
1224 | /** |
1225 | * blkcg_exit_queue - exit and release blkcg part of request_queue | |
1226 | * @q: request_queue being released | |
1227 | * | |
7585d508 | 1228 | * Called from blk_exit_queue(). Responsible for exiting blkcg part. |
5efd6113 TH |
1229 | */ |
1230 | void blkcg_exit_queue(struct request_queue *q) | |
1231 | { | |
3c96cb32 | 1232 | blkg_destroy_all(q); |
5efd6113 TH |
1233 | blk_throtl_exit(q); |
1234 | } | |
1235 | ||
69d7fde5 TH |
1236 | static void blkcg_bind(struct cgroup_subsys_state *root_css) |
1237 | { | |
1238 | int i; | |
1239 | ||
1240 | mutex_lock(&blkcg_pol_mutex); | |
1241 | ||
1242 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
1243 | struct blkcg_policy *pol = blkcg_policy[i]; | |
1244 | struct blkcg *blkcg; | |
1245 | ||
1246 | if (!pol || !pol->cpd_bind_fn) | |
1247 | continue; | |
1248 | ||
1249 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) | |
1250 | if (blkcg->cpd[pol->plid]) | |
1251 | pol->cpd_bind_fn(blkcg->cpd[pol->plid]); | |
1252 | } | |
1253 | mutex_unlock(&blkcg_pol_mutex); | |
1254 | } | |
1255 | ||
d09d8df3 JB |
1256 | static void blkcg_exit(struct task_struct *tsk) |
1257 | { | |
1258 | if (tsk->throttle_queue) | |
1259 | blk_put_queue(tsk->throttle_queue); | |
1260 | tsk->throttle_queue = NULL; | |
1261 | } | |
1262 | ||
c165b3e3 | 1263 | struct cgroup_subsys io_cgrp_subsys = { |
92fb9748 | 1264 | .css_alloc = blkcg_css_alloc, |
4308a434 | 1265 | .css_online = blkcg_css_online, |
92fb9748 TH |
1266 | .css_offline = blkcg_css_offline, |
1267 | .css_free = blkcg_css_free, | |
f7331648 | 1268 | .css_rstat_flush = blkcg_rstat_flush, |
69d7fde5 | 1269 | .bind = blkcg_bind, |
2ee867dc | 1270 | .dfl_cftypes = blkcg_files, |
880f50e2 | 1271 | .legacy_cftypes = blkcg_legacy_files, |
c165b3e3 | 1272 | .legacy_name = "blkio", |
d09d8df3 | 1273 | .exit = blkcg_exit, |
1ced953b TH |
1274 | #ifdef CONFIG_MEMCG |
1275 | /* | |
1276 | * This ensures that, if available, memcg is automatically enabled | |
1277 | * together on the default hierarchy so that the owner cgroup can | |
1278 | * be retrieved from writeback pages. | |
1279 | */ | |
1280 | .depends_on = 1 << memory_cgrp_id, | |
1281 | #endif | |
676f7c8f | 1282 | }; |
c165b3e3 | 1283 | EXPORT_SYMBOL_GPL(io_cgrp_subsys); |
676f7c8f | 1284 | |
a2b1693b TH |
1285 | /** |
1286 | * blkcg_activate_policy - activate a blkcg policy on a request_queue | |
1287 | * @q: request_queue of interest | |
1288 | * @pol: blkcg policy to activate | |
1289 | * | |
1290 | * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through | |
1291 | * bypass mode to populate its blkgs with policy_data for @pol. | |
1292 | * | |
1293 | * Activation happens with @q bypassed, so nobody would be accessing blkgs | |
1294 | * from IO path. Update of each blkg is protected by both queue and blkcg | |
1295 | * locks so that holding either lock and testing blkcg_policy_enabled() is | |
1296 | * always enough for dereferencing policy data. | |
1297 | * | |
1298 | * The caller is responsible for synchronizing [de]activations and policy | |
1299 | * [un]registerations. Returns 0 on success, -errno on failure. | |
1300 | */ | |
1301 | int blkcg_activate_policy(struct request_queue *q, | |
3c798398 | 1302 | const struct blkcg_policy *pol) |
a2b1693b | 1303 | { |
4c55f4f9 | 1304 | struct blkg_policy_data *pd_prealloc = NULL; |
9d179b86 | 1305 | struct blkcg_gq *blkg, *pinned_blkg = NULL; |
4c55f4f9 | 1306 | int ret; |
a2b1693b TH |
1307 | |
1308 | if (blkcg_policy_enabled(q, pol)) | |
1309 | return 0; | |
1310 | ||
344e9ffc | 1311 | if (queue_is_mq(q)) |
bd166ef1 | 1312 | blk_mq_freeze_queue(q); |
9d179b86 | 1313 | retry: |
0d945c1f | 1314 | spin_lock_irq(&q->queue_lock); |
a2b1693b | 1315 | |
9d179b86 | 1316 | /* blkg_list is pushed at the head, reverse walk to allocate parents first */ |
71c81407 | 1317 | list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) { |
4c55f4f9 TH |
1318 | struct blkg_policy_data *pd; |
1319 | ||
1320 | if (blkg->pd[pol->plid]) | |
1321 | continue; | |
a2b1693b | 1322 | |
9d179b86 TH |
1323 | /* If prealloc matches, use it; otherwise try GFP_NOWAIT */ |
1324 | if (blkg == pinned_blkg) { | |
1325 | pd = pd_prealloc; | |
1326 | pd_prealloc = NULL; | |
1327 | } else { | |
1328 | pd = pol->pd_alloc_fn(GFP_NOWAIT | __GFP_NOWARN, q, | |
1329 | blkg->blkcg); | |
1330 | } | |
1331 | ||
4c55f4f9 | 1332 | if (!pd) { |
9d179b86 TH |
1333 | /* |
1334 | * GFP_NOWAIT failed. Free the existing one and | |
1335 | * prealloc for @blkg w/ GFP_KERNEL. | |
1336 | */ | |
1337 | if (pinned_blkg) | |
1338 | blkg_put(pinned_blkg); | |
1339 | blkg_get(blkg); | |
1340 | pinned_blkg = blkg; | |
1341 | ||
0d945c1f | 1342 | spin_unlock_irq(&q->queue_lock); |
9d179b86 TH |
1343 | |
1344 | if (pd_prealloc) | |
1345 | pol->pd_free_fn(pd_prealloc); | |
1346 | pd_prealloc = pol->pd_alloc_fn(GFP_KERNEL, q, | |
1347 | blkg->blkcg); | |
1348 | if (pd_prealloc) | |
1349 | goto retry; | |
1350 | else | |
1351 | goto enomem; | |
4c55f4f9 | 1352 | } |
a2b1693b TH |
1353 | |
1354 | blkg->pd[pol->plid] = pd; | |
1355 | pd->blkg = blkg; | |
b276a876 | 1356 | pd->plid = pol->plid; |
a2b1693b TH |
1357 | } |
1358 | ||
9d179b86 TH |
1359 | /* all allocated, init in the same order */ |
1360 | if (pol->pd_init_fn) | |
1361 | list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) | |
1362 | pol->pd_init_fn(blkg->pd[pol->plid]); | |
1363 | ||
a2b1693b TH |
1364 | __set_bit(pol->plid, q->blkcg_pols); |
1365 | ret = 0; | |
4c55f4f9 | 1366 | |
0d945c1f | 1367 | spin_unlock_irq(&q->queue_lock); |
9d179b86 | 1368 | out: |
344e9ffc | 1369 | if (queue_is_mq(q)) |
bd166ef1 | 1370 | blk_mq_unfreeze_queue(q); |
9d179b86 TH |
1371 | if (pinned_blkg) |
1372 | blkg_put(pinned_blkg); | |
001bea73 TH |
1373 | if (pd_prealloc) |
1374 | pol->pd_free_fn(pd_prealloc); | |
a2b1693b | 1375 | return ret; |
9d179b86 TH |
1376 | |
1377 | enomem: | |
1378 | /* alloc failed, nothing's initialized yet, free everything */ | |
1379 | spin_lock_irq(&q->queue_lock); | |
1380 | list_for_each_entry(blkg, &q->blkg_list, q_node) { | |
858560b2 LJ |
1381 | struct blkcg *blkcg = blkg->blkcg; |
1382 | ||
1383 | spin_lock(&blkcg->lock); | |
9d179b86 TH |
1384 | if (blkg->pd[pol->plid]) { |
1385 | pol->pd_free_fn(blkg->pd[pol->plid]); | |
1386 | blkg->pd[pol->plid] = NULL; | |
1387 | } | |
858560b2 | 1388 | spin_unlock(&blkcg->lock); |
9d179b86 TH |
1389 | } |
1390 | spin_unlock_irq(&q->queue_lock); | |
1391 | ret = -ENOMEM; | |
1392 | goto out; | |
a2b1693b TH |
1393 | } |
1394 | EXPORT_SYMBOL_GPL(blkcg_activate_policy); | |
1395 | ||
1396 | /** | |
1397 | * blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue | |
1398 | * @q: request_queue of interest | |
1399 | * @pol: blkcg policy to deactivate | |
1400 | * | |
1401 | * Deactivate @pol on @q. Follows the same synchronization rules as | |
1402 | * blkcg_activate_policy(). | |
1403 | */ | |
1404 | void blkcg_deactivate_policy(struct request_queue *q, | |
3c798398 | 1405 | const struct blkcg_policy *pol) |
a2b1693b | 1406 | { |
3c798398 | 1407 | struct blkcg_gq *blkg; |
a2b1693b TH |
1408 | |
1409 | if (!blkcg_policy_enabled(q, pol)) | |
1410 | return; | |
1411 | ||
344e9ffc | 1412 | if (queue_is_mq(q)) |
bd166ef1 | 1413 | blk_mq_freeze_queue(q); |
bd166ef1 | 1414 | |
0d945c1f | 1415 | spin_lock_irq(&q->queue_lock); |
a2b1693b TH |
1416 | |
1417 | __clear_bit(pol->plid, q->blkcg_pols); | |
1418 | ||
1419 | list_for_each_entry(blkg, &q->blkg_list, q_node) { | |
858560b2 LJ |
1420 | struct blkcg *blkcg = blkg->blkcg; |
1421 | ||
1422 | spin_lock(&blkcg->lock); | |
001bea73 | 1423 | if (blkg->pd[pol->plid]) { |
6b065462 | 1424 | if (pol->pd_offline_fn) |
a9520cd6 | 1425 | pol->pd_offline_fn(blkg->pd[pol->plid]); |
001bea73 TH |
1426 | pol->pd_free_fn(blkg->pd[pol->plid]); |
1427 | blkg->pd[pol->plid] = NULL; | |
1428 | } | |
858560b2 | 1429 | spin_unlock(&blkcg->lock); |
a2b1693b TH |
1430 | } |
1431 | ||
0d945c1f | 1432 | spin_unlock_irq(&q->queue_lock); |
bd166ef1 | 1433 | |
344e9ffc | 1434 | if (queue_is_mq(q)) |
bd166ef1 | 1435 | blk_mq_unfreeze_queue(q); |
a2b1693b TH |
1436 | } |
1437 | EXPORT_SYMBOL_GPL(blkcg_deactivate_policy); | |
1438 | ||
8bd435b3 | 1439 | /** |
3c798398 TH |
1440 | * blkcg_policy_register - register a blkcg policy |
1441 | * @pol: blkcg policy to register | |
8bd435b3 | 1442 | * |
3c798398 TH |
1443 | * Register @pol with blkcg core. Might sleep and @pol may be modified on |
1444 | * successful registration. Returns 0 on success and -errno on failure. | |
8bd435b3 | 1445 | */ |
d5bf0291 | 1446 | int blkcg_policy_register(struct blkcg_policy *pol) |
3e252066 | 1447 | { |
06b285bd | 1448 | struct blkcg *blkcg; |
8bd435b3 | 1449 | int i, ret; |
e8989fae | 1450 | |
838f13bf | 1451 | mutex_lock(&blkcg_pol_register_mutex); |
bc0d6501 TH |
1452 | mutex_lock(&blkcg_pol_mutex); |
1453 | ||
8bd435b3 TH |
1454 | /* find an empty slot */ |
1455 | ret = -ENOSPC; | |
1456 | for (i = 0; i < BLKCG_MAX_POLS; i++) | |
3c798398 | 1457 | if (!blkcg_policy[i]) |
8bd435b3 | 1458 | break; |
01c5f85a JA |
1459 | if (i >= BLKCG_MAX_POLS) { |
1460 | pr_warn("blkcg_policy_register: BLKCG_MAX_POLS too small\n"); | |
838f13bf | 1461 | goto err_unlock; |
01c5f85a | 1462 | } |
035d10b2 | 1463 | |
e8401073 | 1464 | /* Make sure cpd/pd_alloc_fn and cpd/pd_free_fn in pairs */ |
1465 | if ((!pol->cpd_alloc_fn ^ !pol->cpd_free_fn) || | |
1466 | (!pol->pd_alloc_fn ^ !pol->pd_free_fn)) | |
1467 | goto err_unlock; | |
1468 | ||
06b285bd | 1469 | /* register @pol */ |
3c798398 | 1470 | pol->plid = i; |
06b285bd TH |
1471 | blkcg_policy[pol->plid] = pol; |
1472 | ||
1473 | /* allocate and install cpd's */ | |
e4a9bde9 | 1474 | if (pol->cpd_alloc_fn) { |
06b285bd TH |
1475 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
1476 | struct blkcg_policy_data *cpd; | |
1477 | ||
e4a9bde9 | 1478 | cpd = pol->cpd_alloc_fn(GFP_KERNEL); |
bbb427e3 | 1479 | if (!cpd) |
06b285bd | 1480 | goto err_free_cpds; |
06b285bd | 1481 | |
81437648 TH |
1482 | blkcg->cpd[pol->plid] = cpd; |
1483 | cpd->blkcg = blkcg; | |
06b285bd | 1484 | cpd->plid = pol->plid; |
86a5bba5 TH |
1485 | if (pol->cpd_init_fn) |
1486 | pol->cpd_init_fn(cpd); | |
06b285bd TH |
1487 | } |
1488 | } | |
1489 | ||
838f13bf | 1490 | mutex_unlock(&blkcg_pol_mutex); |
8bd435b3 | 1491 | |
8bd435b3 | 1492 | /* everything is in place, add intf files for the new policy */ |
2ee867dc TH |
1493 | if (pol->dfl_cftypes) |
1494 | WARN_ON(cgroup_add_dfl_cftypes(&io_cgrp_subsys, | |
1495 | pol->dfl_cftypes)); | |
880f50e2 | 1496 | if (pol->legacy_cftypes) |
c165b3e3 | 1497 | WARN_ON(cgroup_add_legacy_cftypes(&io_cgrp_subsys, |
880f50e2 | 1498 | pol->legacy_cftypes)); |
838f13bf TH |
1499 | mutex_unlock(&blkcg_pol_register_mutex); |
1500 | return 0; | |
1501 | ||
06b285bd | 1502 | err_free_cpds: |
58a9edce | 1503 | if (pol->cpd_free_fn) { |
06b285bd | 1504 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
e4a9bde9 TH |
1505 | if (blkcg->cpd[pol->plid]) { |
1506 | pol->cpd_free_fn(blkcg->cpd[pol->plid]); | |
1507 | blkcg->cpd[pol->plid] = NULL; | |
1508 | } | |
06b285bd TH |
1509 | } |
1510 | } | |
1511 | blkcg_policy[pol->plid] = NULL; | |
838f13bf | 1512 | err_unlock: |
bc0d6501 | 1513 | mutex_unlock(&blkcg_pol_mutex); |
838f13bf | 1514 | mutex_unlock(&blkcg_pol_register_mutex); |
8bd435b3 | 1515 | return ret; |
3e252066 | 1516 | } |
3c798398 | 1517 | EXPORT_SYMBOL_GPL(blkcg_policy_register); |
3e252066 | 1518 | |
8bd435b3 | 1519 | /** |
3c798398 TH |
1520 | * blkcg_policy_unregister - unregister a blkcg policy |
1521 | * @pol: blkcg policy to unregister | |
8bd435b3 | 1522 | * |
3c798398 | 1523 | * Undo blkcg_policy_register(@pol). Might sleep. |
8bd435b3 | 1524 | */ |
3c798398 | 1525 | void blkcg_policy_unregister(struct blkcg_policy *pol) |
3e252066 | 1526 | { |
06b285bd TH |
1527 | struct blkcg *blkcg; |
1528 | ||
838f13bf | 1529 | mutex_lock(&blkcg_pol_register_mutex); |
bc0d6501 | 1530 | |
3c798398 | 1531 | if (WARN_ON(blkcg_policy[pol->plid] != pol)) |
8bd435b3 TH |
1532 | goto out_unlock; |
1533 | ||
1534 | /* kill the intf files first */ | |
2ee867dc TH |
1535 | if (pol->dfl_cftypes) |
1536 | cgroup_rm_cftypes(pol->dfl_cftypes); | |
880f50e2 TH |
1537 | if (pol->legacy_cftypes) |
1538 | cgroup_rm_cftypes(pol->legacy_cftypes); | |
44ea53de | 1539 | |
06b285bd | 1540 | /* remove cpds and unregister */ |
838f13bf | 1541 | mutex_lock(&blkcg_pol_mutex); |
06b285bd | 1542 | |
58a9edce | 1543 | if (pol->cpd_free_fn) { |
06b285bd | 1544 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
e4a9bde9 TH |
1545 | if (blkcg->cpd[pol->plid]) { |
1546 | pol->cpd_free_fn(blkcg->cpd[pol->plid]); | |
1547 | blkcg->cpd[pol->plid] = NULL; | |
1548 | } | |
06b285bd TH |
1549 | } |
1550 | } | |
3c798398 | 1551 | blkcg_policy[pol->plid] = NULL; |
06b285bd | 1552 | |
bc0d6501 | 1553 | mutex_unlock(&blkcg_pol_mutex); |
838f13bf TH |
1554 | out_unlock: |
1555 | mutex_unlock(&blkcg_pol_register_mutex); | |
3e252066 | 1556 | } |
3c798398 | 1557 | EXPORT_SYMBOL_GPL(blkcg_policy_unregister); |
903d23f0 | 1558 | |
d3f77dfd TH |
1559 | bool __blkcg_punt_bio_submit(struct bio *bio) |
1560 | { | |
1561 | struct blkcg_gq *blkg = bio->bi_blkg; | |
1562 | ||
1563 | /* consume the flag first */ | |
1564 | bio->bi_opf &= ~REQ_CGROUP_PUNT; | |
1565 | ||
1566 | /* never bounce for the root cgroup */ | |
1567 | if (!blkg->parent) | |
1568 | return false; | |
1569 | ||
1570 | spin_lock_bh(&blkg->async_bio_lock); | |
1571 | bio_list_add(&blkg->async_bios, bio); | |
1572 | spin_unlock_bh(&blkg->async_bio_lock); | |
1573 | ||
1574 | queue_work(blkcg_punt_bio_wq, &blkg->async_bio_work); | |
1575 | return true; | |
1576 | } | |
1577 | ||
d09d8df3 JB |
1578 | /* |
1579 | * Scale the accumulated delay based on how long it has been since we updated | |
1580 | * the delay. We only call this when we are adding delay, in case it's been a | |
1581 | * while since we added delay, and when we are checking to see if we need to | |
1582 | * delay a task, to account for any delays that may have occurred. | |
1583 | */ | |
1584 | static void blkcg_scale_delay(struct blkcg_gq *blkg, u64 now) | |
1585 | { | |
1586 | u64 old = atomic64_read(&blkg->delay_start); | |
1587 | ||
54c52e10 TH |
1588 | /* negative use_delay means no scaling, see blkcg_set_delay() */ |
1589 | if (atomic_read(&blkg->use_delay) < 0) | |
1590 | return; | |
1591 | ||
d09d8df3 JB |
1592 | /* |
1593 | * We only want to scale down every second. The idea here is that we | |
1594 | * want to delay people for min(delay_nsec, NSEC_PER_SEC) in a certain | |
1595 | * time window. We only want to throttle tasks for recent delay that | |
1596 | * has occurred, in 1 second time windows since that's the maximum | |
1597 | * things can be throttled. We save the current delay window in | |
1598 | * blkg->last_delay so we know what amount is still left to be charged | |
1599 | * to the blkg from this point onward. blkg->last_use keeps track of | |
1600 | * the use_delay counter. The idea is if we're unthrottling the blkg we | |
1601 | * are ok with whatever is happening now, and we can take away more of | |
1602 | * the accumulated delay as we've already throttled enough that | |
1603 | * everybody is happy with their IO latencies. | |
1604 | */ | |
1605 | if (time_before64(old + NSEC_PER_SEC, now) && | |
1606 | atomic64_cmpxchg(&blkg->delay_start, old, now) == old) { | |
1607 | u64 cur = atomic64_read(&blkg->delay_nsec); | |
1608 | u64 sub = min_t(u64, blkg->last_delay, now - old); | |
1609 | int cur_use = atomic_read(&blkg->use_delay); | |
1610 | ||
1611 | /* | |
1612 | * We've been unthrottled, subtract a larger chunk of our | |
1613 | * accumulated delay. | |
1614 | */ | |
1615 | if (cur_use < blkg->last_use) | |
1616 | sub = max_t(u64, sub, blkg->last_delay >> 1); | |
1617 | ||
1618 | /* | |
1619 | * This shouldn't happen, but handle it anyway. Our delay_nsec | |
1620 | * should only ever be growing except here where we subtract out | |
1621 | * min(last_delay, 1 second), but lord knows bugs happen and I'd | |
1622 | * rather not end up with negative numbers. | |
1623 | */ | |
1624 | if (unlikely(cur < sub)) { | |
1625 | atomic64_set(&blkg->delay_nsec, 0); | |
1626 | blkg->last_delay = 0; | |
1627 | } else { | |
1628 | atomic64_sub(sub, &blkg->delay_nsec); | |
1629 | blkg->last_delay = cur - sub; | |
1630 | } | |
1631 | blkg->last_use = cur_use; | |
1632 | } | |
1633 | } | |
1634 | ||
1635 | /* | |
1636 | * This is called when we want to actually walk up the hierarchy and check to | |
1637 | * see if we need to throttle, and then actually throttle if there is some | |
1638 | * accumulated delay. This should only be called upon return to user space so | |
1639 | * we're not holding some lock that would induce a priority inversion. | |
1640 | */ | |
1641 | static void blkcg_maybe_throttle_blkg(struct blkcg_gq *blkg, bool use_memdelay) | |
1642 | { | |
fd112c74 | 1643 | unsigned long pflags; |
5160a5a5 | 1644 | bool clamp; |
d09d8df3 JB |
1645 | u64 now = ktime_to_ns(ktime_get()); |
1646 | u64 exp; | |
1647 | u64 delay_nsec = 0; | |
1648 | int tok; | |
1649 | ||
1650 | while (blkg->parent) { | |
5160a5a5 TH |
1651 | int use_delay = atomic_read(&blkg->use_delay); |
1652 | ||
1653 | if (use_delay) { | |
1654 | u64 this_delay; | |
1655 | ||
d09d8df3 | 1656 | blkcg_scale_delay(blkg, now); |
5160a5a5 TH |
1657 | this_delay = atomic64_read(&blkg->delay_nsec); |
1658 | if (this_delay > delay_nsec) { | |
1659 | delay_nsec = this_delay; | |
1660 | clamp = use_delay > 0; | |
1661 | } | |
d09d8df3 JB |
1662 | } |
1663 | blkg = blkg->parent; | |
1664 | } | |
1665 | ||
1666 | if (!delay_nsec) | |
1667 | return; | |
1668 | ||
1669 | /* | |
1670 | * Let's not sleep for all eternity if we've amassed a huge delay. | |
1671 | * Swapping or metadata IO can accumulate 10's of seconds worth of | |
1672 | * delay, and we want userspace to be able to do _something_ so cap the | |
5160a5a5 TH |
1673 | * delays at 0.25s. If there's 10's of seconds worth of delay then the |
1674 | * tasks will be delayed for 0.25 second for every syscall. If | |
1675 | * blkcg_set_delay() was used as indicated by negative use_delay, the | |
1676 | * caller is responsible for regulating the range. | |
d09d8df3 | 1677 | */ |
5160a5a5 TH |
1678 | if (clamp) |
1679 | delay_nsec = min_t(u64, delay_nsec, 250 * NSEC_PER_MSEC); | |
d09d8df3 | 1680 | |
fd112c74 JB |
1681 | if (use_memdelay) |
1682 | psi_memstall_enter(&pflags); | |
d09d8df3 JB |
1683 | |
1684 | exp = ktime_add_ns(now, delay_nsec); | |
1685 | tok = io_schedule_prepare(); | |
1686 | do { | |
1687 | __set_current_state(TASK_KILLABLE); | |
1688 | if (!schedule_hrtimeout(&exp, HRTIMER_MODE_ABS)) | |
1689 | break; | |
1690 | } while (!fatal_signal_pending(current)); | |
1691 | io_schedule_finish(tok); | |
fd112c74 JB |
1692 | |
1693 | if (use_memdelay) | |
1694 | psi_memstall_leave(&pflags); | |
d09d8df3 JB |
1695 | } |
1696 | ||
1697 | /** | |
1698 | * blkcg_maybe_throttle_current - throttle the current task if it has been marked | |
1699 | * | |
1700 | * This is only called if we've been marked with set_notify_resume(). Obviously | |
1701 | * we can be set_notify_resume() for reasons other than blkcg throttling, so we | |
1702 | * check to see if current->throttle_queue is set and if not this doesn't do | |
1703 | * anything. This should only ever be called by the resume code, it's not meant | |
1704 | * to be called by people willy-nilly as it will actually do the work to | |
1705 | * throttle the task if it is setup for throttling. | |
1706 | */ | |
1707 | void blkcg_maybe_throttle_current(void) | |
1708 | { | |
1709 | struct request_queue *q = current->throttle_queue; | |
1710 | struct cgroup_subsys_state *css; | |
1711 | struct blkcg *blkcg; | |
1712 | struct blkcg_gq *blkg; | |
1713 | bool use_memdelay = current->use_memdelay; | |
1714 | ||
1715 | if (!q) | |
1716 | return; | |
1717 | ||
1718 | current->throttle_queue = NULL; | |
1719 | current->use_memdelay = false; | |
1720 | ||
1721 | rcu_read_lock(); | |
1722 | css = kthread_blkcg(); | |
1723 | if (css) | |
1724 | blkcg = css_to_blkcg(css); | |
1725 | else | |
1726 | blkcg = css_to_blkcg(task_css(current, io_cgrp_id)); | |
1727 | ||
1728 | if (!blkcg) | |
1729 | goto out; | |
1730 | blkg = blkg_lookup(blkcg, q); | |
1731 | if (!blkg) | |
1732 | goto out; | |
7754f669 | 1733 | if (!blkg_tryget(blkg)) |
d09d8df3 JB |
1734 | goto out; |
1735 | rcu_read_unlock(); | |
d09d8df3 JB |
1736 | |
1737 | blkcg_maybe_throttle_blkg(blkg, use_memdelay); | |
1738 | blkg_put(blkg); | |
cc7ecc25 | 1739 | blk_put_queue(q); |
d09d8df3 JB |
1740 | return; |
1741 | out: | |
1742 | rcu_read_unlock(); | |
1743 | blk_put_queue(q); | |
1744 | } | |
d09d8df3 JB |
1745 | |
1746 | /** | |
1747 | * blkcg_schedule_throttle - this task needs to check for throttling | |
537d71b3 BVA |
1748 | * @q: the request queue IO was submitted on |
1749 | * @use_memdelay: do we charge this to memory delay for PSI | |
d09d8df3 JB |
1750 | * |
1751 | * This is called by the IO controller when we know there's delay accumulated | |
1752 | * for the blkg for this task. We do not pass the blkg because there are places | |
1753 | * we call this that may not have that information, the swapping code for | |
1754 | * instance will only have a request_queue at that point. This set's the | |
1755 | * notify_resume for the task to check and see if it requires throttling before | |
1756 | * returning to user space. | |
1757 | * | |
1758 | * We will only schedule once per syscall. You can call this over and over | |
1759 | * again and it will only do the check once upon return to user space, and only | |
1760 | * throttle once. If the task needs to be throttled again it'll need to be | |
1761 | * re-set at the next time we see the task. | |
1762 | */ | |
1763 | void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay) | |
1764 | { | |
1765 | if (unlikely(current->flags & PF_KTHREAD)) | |
1766 | return; | |
1767 | ||
49d1822b CX |
1768 | if (current->throttle_queue != q) { |
1769 | if (!blk_get_queue(q)) | |
1770 | return; | |
1771 | ||
1772 | if (current->throttle_queue) | |
1773 | blk_put_queue(current->throttle_queue); | |
1774 | current->throttle_queue = q; | |
1775 | } | |
d09d8df3 | 1776 | |
d09d8df3 JB |
1777 | if (use_memdelay) |
1778 | current->use_memdelay = use_memdelay; | |
1779 | set_notify_resume(current); | |
1780 | } | |
d09d8df3 JB |
1781 | |
1782 | /** | |
1783 | * blkcg_add_delay - add delay to this blkg | |
537d71b3 BVA |
1784 | * @blkg: blkg of interest |
1785 | * @now: the current time in nanoseconds | |
1786 | * @delta: how many nanoseconds of delay to add | |
d09d8df3 JB |
1787 | * |
1788 | * Charge @delta to the blkg's current delay accumulation. This is used to | |
1789 | * throttle tasks if an IO controller thinks we need more throttling. | |
1790 | */ | |
1791 | void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta) | |
1792 | { | |
54c52e10 TH |
1793 | if (WARN_ON_ONCE(atomic_read(&blkg->use_delay) < 0)) |
1794 | return; | |
d09d8df3 JB |
1795 | blkcg_scale_delay(blkg, now); |
1796 | atomic64_add(delta, &blkg->delay_nsec); | |
1797 | } | |
d09d8df3 | 1798 | |
28fc591f CH |
1799 | /** |
1800 | * blkg_tryget_closest - try and get a blkg ref on the closet blkg | |
13c7863d CH |
1801 | * @bio: target bio |
1802 | * @css: target css | |
28fc591f | 1803 | * |
13c7863d CH |
1804 | * As the failure mode here is to walk up the blkg tree, this ensure that the |
1805 | * blkg->parent pointers are always valid. This returns the blkg that it ended | |
1806 | * up taking a reference on or %NULL if no reference was taken. | |
28fc591f | 1807 | */ |
13c7863d CH |
1808 | static inline struct blkcg_gq *blkg_tryget_closest(struct bio *bio, |
1809 | struct cgroup_subsys_state *css) | |
28fc591f | 1810 | { |
13c7863d | 1811 | struct blkcg_gq *blkg, *ret_blkg = NULL; |
28fc591f | 1812 | |
13c7863d | 1813 | rcu_read_lock(); |
309dca30 | 1814 | blkg = blkg_lookup_create(css_to_blkcg(css), |
ed6cddef | 1815 | bdev_get_queue(bio->bi_bdev)); |
28fc591f CH |
1816 | while (blkg) { |
1817 | if (blkg_tryget(blkg)) { | |
1818 | ret_blkg = blkg; | |
1819 | break; | |
1820 | } | |
1821 | blkg = blkg->parent; | |
1822 | } | |
13c7863d | 1823 | rcu_read_unlock(); |
28fc591f CH |
1824 | |
1825 | return ret_blkg; | |
1826 | } | |
1827 | ||
1828 | /** | |
1829 | * bio_associate_blkg_from_css - associate a bio with a specified css | |
1830 | * @bio: target bio | |
1831 | * @css: target css | |
1832 | * | |
1833 | * Associate @bio with the blkg found by combining the css's blkg and the | |
1834 | * request_queue of the @bio. An association failure is handled by walking up | |
1835 | * the blkg tree. Therefore, the blkg associated can be anything between @blkg | |
1836 | * and q->root_blkg. This situation only happens when a cgroup is dying and | |
1837 | * then the remaining bios will spill to the closest alive blkg. | |
1838 | * | |
1839 | * A reference will be taken on the blkg and will be released when @bio is | |
1840 | * freed. | |
1841 | */ | |
1842 | void bio_associate_blkg_from_css(struct bio *bio, | |
1843 | struct cgroup_subsys_state *css) | |
1844 | { | |
28fc591f CH |
1845 | if (bio->bi_blkg) |
1846 | blkg_put(bio->bi_blkg); | |
1847 | ||
a5b97526 | 1848 | if (css && css->parent) { |
13c7863d | 1849 | bio->bi_blkg = blkg_tryget_closest(bio, css); |
a5b97526 | 1850 | } else { |
ed6cddef PB |
1851 | blkg_get(bdev_get_queue(bio->bi_bdev)->root_blkg); |
1852 | bio->bi_blkg = bdev_get_queue(bio->bi_bdev)->root_blkg; | |
a5b97526 | 1853 | } |
28fc591f CH |
1854 | } |
1855 | EXPORT_SYMBOL_GPL(bio_associate_blkg_from_css); | |
1856 | ||
1857 | /** | |
1858 | * bio_associate_blkg - associate a bio with a blkg | |
1859 | * @bio: target bio | |
1860 | * | |
1861 | * Associate @bio with the blkg found from the bio's css and request_queue. | |
1862 | * If one is not found, bio_lookup_blkg() creates the blkg. If a blkg is | |
1863 | * already associated, the css is reused and association redone as the | |
1864 | * request_queue may have changed. | |
1865 | */ | |
1866 | void bio_associate_blkg(struct bio *bio) | |
1867 | { | |
1868 | struct cgroup_subsys_state *css; | |
1869 | ||
1870 | rcu_read_lock(); | |
1871 | ||
1872 | if (bio->bi_blkg) | |
1873 | css = &bio_blkcg(bio)->css; | |
1874 | else | |
1875 | css = blkcg_css(); | |
1876 | ||
1877 | bio_associate_blkg_from_css(bio, css); | |
1878 | ||
1879 | rcu_read_unlock(); | |
1880 | } | |
1881 | EXPORT_SYMBOL_GPL(bio_associate_blkg); | |
1882 | ||
1883 | /** | |
1884 | * bio_clone_blkg_association - clone blkg association from src to dst bio | |
1885 | * @dst: destination bio | |
1886 | * @src: source bio | |
1887 | */ | |
1888 | void bio_clone_blkg_association(struct bio *dst, struct bio *src) | |
1889 | { | |
1890 | if (src->bi_blkg) { | |
1891 | if (dst->bi_blkg) | |
1892 | blkg_put(dst->bi_blkg); | |
1893 | blkg_get(src->bi_blkg); | |
1894 | dst->bi_blkg = src->bi_blkg; | |
1895 | } | |
1896 | } | |
1897 | EXPORT_SYMBOL_GPL(bio_clone_blkg_association); | |
1898 | ||
db18a53e CH |
1899 | static int blk_cgroup_io_type(struct bio *bio) |
1900 | { | |
1901 | if (op_is_discard(bio->bi_opf)) | |
1902 | return BLKG_IOSTAT_DISCARD; | |
1903 | if (op_is_write(bio->bi_opf)) | |
1904 | return BLKG_IOSTAT_WRITE; | |
1905 | return BLKG_IOSTAT_READ; | |
1906 | } | |
1907 | ||
1908 | void blk_cgroup_bio_start(struct bio *bio) | |
1909 | { | |
1910 | int rwd = blk_cgroup_io_type(bio), cpu; | |
1911 | struct blkg_iostat_set *bis; | |
3c08b093 | 1912 | unsigned long flags; |
db18a53e CH |
1913 | |
1914 | cpu = get_cpu(); | |
1915 | bis = per_cpu_ptr(bio->bi_blkg->iostat_cpu, cpu); | |
3c08b093 | 1916 | flags = u64_stats_update_begin_irqsave(&bis->sync); |
db18a53e CH |
1917 | |
1918 | /* | |
1919 | * If the bio is flagged with BIO_CGROUP_ACCT it means this is a split | |
1920 | * bio and we would have already accounted for the size of the bio. | |
1921 | */ | |
1922 | if (!bio_flagged(bio, BIO_CGROUP_ACCT)) { | |
1923 | bio_set_flag(bio, BIO_CGROUP_ACCT); | |
0b8cc25d | 1924 | bis->cur.bytes[rwd] += bio->bi_iter.bi_size; |
db18a53e CH |
1925 | } |
1926 | bis->cur.ios[rwd]++; | |
1927 | ||
3c08b093 | 1928 | u64_stats_update_end_irqrestore(&bis->sync, flags); |
db18a53e CH |
1929 | if (cgroup_subsys_on_dfl(io_cgrp_subsys)) |
1930 | cgroup_rstat_updated(bio->bi_blkg->blkcg->css.cgroup, cpu); | |
1931 | put_cpu(); | |
1932 | } | |
1933 | ||
d3f77dfd TH |
1934 | static int __init blkcg_init(void) |
1935 | { | |
1936 | blkcg_punt_bio_wq = alloc_workqueue("blkcg_punt_bio", | |
1937 | WQ_MEM_RECLAIM | WQ_FREEZABLE | | |
1938 | WQ_UNBOUND | WQ_SYSFS, 0); | |
1939 | if (!blkcg_punt_bio_wq) | |
1940 | return -ENOMEM; | |
1941 | return 0; | |
1942 | } | |
1943 | subsys_initcall(blkcg_init); | |
1944 | ||
903d23f0 JB |
1945 | module_param(blkcg_debug_stats, bool, 0644); |
1946 | MODULE_PARM_DESC(blkcg_debug_stats, "True if you want debug stats, false if not"); |