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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 | ||
903d23f0 | 57 | static 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 | |
77ea7338 TH |
83 | blkg_rwstat_exit(&blkg->stat_ios); |
84 | blkg_rwstat_exit(&blkg->stat_bytes); | |
ef069b97 | 85 | percpu_ref_exit(&blkg->refcnt); |
549d3aa8 | 86 | kfree(blkg); |
0381411e TH |
87 | } |
88 | ||
7fcf2b03 DZ |
89 | static void __blkg_release(struct rcu_head *rcu) |
90 | { | |
91 | struct blkcg_gq *blkg = container_of(rcu, struct blkcg_gq, rcu_head); | |
92 | ||
d3f77dfd TH |
93 | WARN_ON(!bio_list_empty(&blkg->async_bios)); |
94 | ||
7fcf2b03 DZ |
95 | /* release the blkcg and parent blkg refs this blkg has been holding */ |
96 | css_put(&blkg->blkcg->css); | |
97 | if (blkg->parent) | |
98 | blkg_put(blkg->parent); | |
99 | ||
100 | wb_congested_put(blkg->wb_congested); | |
101 | ||
102 | blkg_free(blkg); | |
103 | } | |
104 | ||
105 | /* | |
106 | * A group is RCU protected, but having an rcu lock does not mean that one | |
107 | * can access all the fields of blkg and assume these are valid. For | |
108 | * example, don't try to follow throtl_data and request queue links. | |
109 | * | |
110 | * Having a reference to blkg under an rcu allows accesses to only values | |
111 | * local to groups like group stats and group rate limits. | |
112 | */ | |
113 | static void blkg_release(struct percpu_ref *ref) | |
114 | { | |
115 | struct blkcg_gq *blkg = container_of(ref, struct blkcg_gq, refcnt); | |
116 | ||
117 | call_rcu(&blkg->rcu_head, __blkg_release); | |
118 | } | |
119 | ||
d3f77dfd TH |
120 | static void blkg_async_bio_workfn(struct work_struct *work) |
121 | { | |
122 | struct blkcg_gq *blkg = container_of(work, struct blkcg_gq, | |
123 | async_bio_work); | |
124 | struct bio_list bios = BIO_EMPTY_LIST; | |
125 | struct bio *bio; | |
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 | ||
133 | while ((bio = bio_list_pop(&bios))) | |
134 | submit_bio(bio); | |
135 | } | |
136 | ||
0381411e TH |
137 | /** |
138 | * blkg_alloc - allocate a blkg | |
139 | * @blkcg: block cgroup the new blkg is associated with | |
140 | * @q: request_queue the new blkg is associated with | |
15974993 | 141 | * @gfp_mask: allocation mask to use |
0381411e | 142 | * |
e8989fae | 143 | * Allocate a new blkg assocating @blkcg and @q. |
0381411e | 144 | */ |
15974993 TH |
145 | static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, |
146 | gfp_t gfp_mask) | |
0381411e | 147 | { |
3c798398 | 148 | struct blkcg_gq *blkg; |
e8989fae | 149 | int i; |
0381411e TH |
150 | |
151 | /* alloc and init base part */ | |
15974993 | 152 | blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node); |
0381411e TH |
153 | if (!blkg) |
154 | return NULL; | |
155 | ||
ef069b97 TH |
156 | if (percpu_ref_init(&blkg->refcnt, blkg_release, 0, gfp_mask)) |
157 | goto err_free; | |
158 | ||
77ea7338 TH |
159 | if (blkg_rwstat_init(&blkg->stat_bytes, gfp_mask) || |
160 | blkg_rwstat_init(&blkg->stat_ios, gfp_mask)) | |
161 | goto err_free; | |
162 | ||
c875f4d0 | 163 | blkg->q = q; |
e8989fae | 164 | INIT_LIST_HEAD(&blkg->q_node); |
d3f77dfd TH |
165 | spin_lock_init(&blkg->async_bio_lock); |
166 | bio_list_init(&blkg->async_bios); | |
167 | INIT_WORK(&blkg->async_bio_work, blkg_async_bio_workfn); | |
0381411e | 168 | blkg->blkcg = blkcg; |
0381411e | 169 | |
8bd435b3 | 170 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
3c798398 | 171 | struct blkcg_policy *pol = blkcg_policy[i]; |
e8989fae | 172 | struct blkg_policy_data *pd; |
0381411e | 173 | |
a2b1693b | 174 | if (!blkcg_policy_enabled(q, pol)) |
e8989fae TH |
175 | continue; |
176 | ||
177 | /* alloc per-policy data and attach it to blkg */ | |
001bea73 | 178 | pd = pol->pd_alloc_fn(gfp_mask, q->node); |
a051661c TH |
179 | if (!pd) |
180 | goto err_free; | |
549d3aa8 | 181 | |
e8989fae TH |
182 | blkg->pd[i] = pd; |
183 | pd->blkg = blkg; | |
b276a876 | 184 | pd->plid = i; |
e8989fae TH |
185 | } |
186 | ||
0381411e | 187 | return blkg; |
a051661c TH |
188 | |
189 | err_free: | |
190 | blkg_free(blkg); | |
191 | return NULL; | |
0381411e TH |
192 | } |
193 | ||
24f29046 TH |
194 | struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg, |
195 | struct request_queue *q, bool update_hint) | |
80fd9979 | 196 | { |
3c798398 | 197 | struct blkcg_gq *blkg; |
80fd9979 | 198 | |
a637120e | 199 | /* |
86cde6b6 TH |
200 | * Hint didn't match. Look up from the radix tree. Note that the |
201 | * hint can only be updated under queue_lock as otherwise @blkg | |
202 | * could have already been removed from blkg_tree. The caller is | |
203 | * responsible for grabbing queue_lock if @update_hint. | |
a637120e TH |
204 | */ |
205 | blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); | |
86cde6b6 TH |
206 | if (blkg && blkg->q == q) { |
207 | if (update_hint) { | |
0d945c1f | 208 | lockdep_assert_held(&q->queue_lock); |
86cde6b6 TH |
209 | rcu_assign_pointer(blkcg->blkg_hint, blkg); |
210 | } | |
a637120e | 211 | return blkg; |
86cde6b6 | 212 | } |
a637120e | 213 | |
80fd9979 TH |
214 | return NULL; |
215 | } | |
ae118896 | 216 | EXPORT_SYMBOL_GPL(blkg_lookup_slowpath); |
80fd9979 | 217 | |
15974993 | 218 | /* |
d708f0d5 JA |
219 | * If @new_blkg is %NULL, this function tries to allocate a new one as |
220 | * necessary using %GFP_NOWAIT. @new_blkg is always consumed on return. | |
15974993 | 221 | */ |
86cde6b6 | 222 | static struct blkcg_gq *blkg_create(struct blkcg *blkcg, |
d708f0d5 JA |
223 | struct request_queue *q, |
224 | struct blkcg_gq *new_blkg) | |
5624a4e4 | 225 | { |
d708f0d5 | 226 | struct blkcg_gq *blkg; |
ce7acfea | 227 | struct bdi_writeback_congested *wb_congested; |
f427d909 | 228 | int i, ret; |
5624a4e4 | 229 | |
cd1604fa | 230 | WARN_ON_ONCE(!rcu_read_lock_held()); |
0d945c1f | 231 | lockdep_assert_held(&q->queue_lock); |
cd1604fa | 232 | |
0273ac34 DZ |
233 | /* request_queue is dying, do not create/recreate a blkg */ |
234 | if (blk_queue_dying(q)) { | |
235 | ret = -ENODEV; | |
236 | goto err_free_blkg; | |
237 | } | |
238 | ||
7ee9c562 | 239 | /* blkg holds a reference to blkcg */ |
ec903c0c | 240 | if (!css_tryget_online(&blkcg->css)) { |
20386ce0 | 241 | ret = -ENODEV; |
93e6d5d8 | 242 | goto err_free_blkg; |
15974993 | 243 | } |
cd1604fa | 244 | |
dc3b17cc | 245 | wb_congested = wb_congested_get_create(q->backing_dev_info, |
d708f0d5 JA |
246 | blkcg->css.id, |
247 | GFP_NOWAIT | __GFP_NOWARN); | |
248 | if (!wb_congested) { | |
ce7acfea | 249 | ret = -ENOMEM; |
d708f0d5 | 250 | goto err_put_css; |
ce7acfea TH |
251 | } |
252 | ||
d708f0d5 JA |
253 | /* allocate */ |
254 | if (!new_blkg) { | |
255 | new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT | __GFP_NOWARN); | |
256 | if (unlikely(!new_blkg)) { | |
257 | ret = -ENOMEM; | |
258 | goto err_put_congested; | |
15974993 TH |
259 | } |
260 | } | |
d708f0d5 JA |
261 | blkg = new_blkg; |
262 | blkg->wb_congested = wb_congested; | |
cd1604fa | 263 | |
db613670 | 264 | /* link parent */ |
3c547865 TH |
265 | if (blkcg_parent(blkcg)) { |
266 | blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false); | |
267 | if (WARN_ON_ONCE(!blkg->parent)) { | |
20386ce0 | 268 | ret = -ENODEV; |
d708f0d5 | 269 | goto err_put_congested; |
3c547865 TH |
270 | } |
271 | blkg_get(blkg->parent); | |
272 | } | |
273 | ||
db613670 TH |
274 | /* invoke per-policy init */ |
275 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
276 | struct blkcg_policy *pol = blkcg_policy[i]; | |
277 | ||
278 | if (blkg->pd[i] && pol->pd_init_fn) | |
a9520cd6 | 279 | pol->pd_init_fn(blkg->pd[i]); |
db613670 TH |
280 | } |
281 | ||
282 | /* insert */ | |
cd1604fa | 283 | spin_lock(&blkcg->lock); |
a637120e TH |
284 | ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg); |
285 | if (likely(!ret)) { | |
286 | hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); | |
287 | list_add(&blkg->q_node, &q->blkg_list); | |
f427d909 TH |
288 | |
289 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
290 | struct blkcg_policy *pol = blkcg_policy[i]; | |
291 | ||
292 | if (blkg->pd[i] && pol->pd_online_fn) | |
a9520cd6 | 293 | pol->pd_online_fn(blkg->pd[i]); |
f427d909 | 294 | } |
a637120e | 295 | } |
f427d909 | 296 | blkg->online = true; |
cd1604fa | 297 | spin_unlock(&blkcg->lock); |
496fb780 | 298 | |
ec13b1d6 | 299 | if (!ret) |
a637120e | 300 | return blkg; |
15974993 | 301 | |
3c547865 TH |
302 | /* @blkg failed fully initialized, use the usual release path */ |
303 | blkg_put(blkg); | |
304 | return ERR_PTR(ret); | |
305 | ||
d708f0d5 JA |
306 | err_put_congested: |
307 | wb_congested_put(wb_congested); | |
308 | err_put_css: | |
496fb780 | 309 | css_put(&blkcg->css); |
93e6d5d8 | 310 | err_free_blkg: |
d708f0d5 | 311 | blkg_free(new_blkg); |
93e6d5d8 | 312 | return ERR_PTR(ret); |
31e4c28d | 313 | } |
3c96cb32 | 314 | |
86cde6b6 | 315 | /** |
b978962a | 316 | * __blkg_lookup_create - lookup blkg, try to create one if not there |
86cde6b6 TH |
317 | * @blkcg: blkcg of interest |
318 | * @q: request_queue of interest | |
319 | * | |
320 | * Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to | |
3c547865 TH |
321 | * create one. blkg creation is performed recursively from blkcg_root such |
322 | * that all non-root blkg's have access to the parent blkg. This function | |
323 | * should be called under RCU read lock and @q->queue_lock. | |
86cde6b6 | 324 | * |
beea9da0 DZ |
325 | * Returns the blkg or the closest blkg if blkg_create() fails as it walks |
326 | * down from root. | |
86cde6b6 | 327 | */ |
b978962a DZ |
328 | struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, |
329 | struct request_queue *q) | |
3c96cb32 | 330 | { |
86cde6b6 TH |
331 | struct blkcg_gq *blkg; |
332 | ||
333 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
0d945c1f | 334 | lockdep_assert_held(&q->queue_lock); |
86cde6b6 | 335 | |
86cde6b6 TH |
336 | blkg = __blkg_lookup(blkcg, q, true); |
337 | if (blkg) | |
338 | return blkg; | |
339 | ||
3c547865 TH |
340 | /* |
341 | * Create blkgs walking down from blkcg_root to @blkcg, so that all | |
beea9da0 DZ |
342 | * non-root blkgs have access to their parents. Returns the closest |
343 | * blkg to the intended blkg should blkg_create() fail. | |
3c547865 TH |
344 | */ |
345 | while (true) { | |
346 | struct blkcg *pos = blkcg; | |
347 | struct blkcg *parent = blkcg_parent(blkcg); | |
beea9da0 DZ |
348 | struct blkcg_gq *ret_blkg = q->root_blkg; |
349 | ||
350 | while (parent) { | |
351 | blkg = __blkg_lookup(parent, q, false); | |
352 | if (blkg) { | |
353 | /* remember closest blkg */ | |
354 | ret_blkg = blkg; | |
355 | break; | |
356 | } | |
3c547865 TH |
357 | pos = parent; |
358 | parent = blkcg_parent(parent); | |
359 | } | |
360 | ||
d708f0d5 | 361 | blkg = blkg_create(pos, q, NULL); |
beea9da0 DZ |
362 | if (IS_ERR(blkg)) |
363 | return ret_blkg; | |
364 | if (pos == blkcg) | |
3c547865 TH |
365 | return blkg; |
366 | } | |
3c96cb32 | 367 | } |
31e4c28d | 368 | |
b978962a DZ |
369 | /** |
370 | * blkg_lookup_create - find or create a blkg | |
371 | * @blkcg: target block cgroup | |
372 | * @q: target request_queue | |
373 | * | |
374 | * This looks up or creates the blkg representing the unique pair | |
375 | * of the blkcg and the request_queue. | |
376 | */ | |
377 | struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, | |
378 | struct request_queue *q) | |
379 | { | |
380 | struct blkcg_gq *blkg = blkg_lookup(blkcg, q); | |
381 | ||
382 | if (unlikely(!blkg)) { | |
3a762de5 ML |
383 | unsigned long flags; |
384 | ||
385 | spin_lock_irqsave(&q->queue_lock, flags); | |
b978962a | 386 | blkg = __blkg_lookup_create(blkcg, q); |
3a762de5 | 387 | spin_unlock_irqrestore(&q->queue_lock, flags); |
b978962a DZ |
388 | } |
389 | ||
390 | return blkg; | |
391 | } | |
392 | ||
3c798398 | 393 | static void blkg_destroy(struct blkcg_gq *blkg) |
03aa264a | 394 | { |
3c798398 | 395 | struct blkcg *blkcg = blkg->blkcg; |
77ea7338 | 396 | struct blkcg_gq *parent = blkg->parent; |
6b065462 | 397 | int i; |
03aa264a | 398 | |
0d945c1f | 399 | lockdep_assert_held(&blkg->q->queue_lock); |
9f13ef67 | 400 | lockdep_assert_held(&blkcg->lock); |
03aa264a TH |
401 | |
402 | /* Something wrong if we are trying to remove same group twice */ | |
e8989fae | 403 | WARN_ON_ONCE(list_empty(&blkg->q_node)); |
9f13ef67 | 404 | WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node)); |
a637120e | 405 | |
6b065462 DZF |
406 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
407 | struct blkcg_policy *pol = blkcg_policy[i]; | |
408 | ||
409 | if (blkg->pd[i] && pol->pd_offline_fn) | |
410 | pol->pd_offline_fn(blkg->pd[i]); | |
411 | } | |
412 | ||
77ea7338 TH |
413 | if (parent) { |
414 | blkg_rwstat_add_aux(&parent->stat_bytes, &blkg->stat_bytes); | |
415 | blkg_rwstat_add_aux(&parent->stat_ios, &blkg->stat_ios); | |
416 | } | |
417 | ||
f427d909 TH |
418 | blkg->online = false; |
419 | ||
a637120e | 420 | radix_tree_delete(&blkcg->blkg_tree, blkg->q->id); |
e8989fae | 421 | list_del_init(&blkg->q_node); |
9f13ef67 | 422 | hlist_del_init_rcu(&blkg->blkcg_node); |
03aa264a | 423 | |
a637120e TH |
424 | /* |
425 | * Both setting lookup hint to and clearing it from @blkg are done | |
426 | * under queue_lock. If it's not pointing to @blkg now, it never | |
427 | * will. Hint assignment itself can race safely. | |
428 | */ | |
ec6c676a | 429 | if (rcu_access_pointer(blkcg->blkg_hint) == blkg) |
a637120e TH |
430 | rcu_assign_pointer(blkcg->blkg_hint, NULL); |
431 | ||
03aa264a TH |
432 | /* |
433 | * Put the reference taken at the time of creation so that when all | |
434 | * queues are gone, group can be destroyed. | |
435 | */ | |
7fcf2b03 | 436 | percpu_ref_kill(&blkg->refcnt); |
03aa264a TH |
437 | } |
438 | ||
9f13ef67 TH |
439 | /** |
440 | * blkg_destroy_all - destroy all blkgs associated with a request_queue | |
441 | * @q: request_queue of interest | |
9f13ef67 | 442 | * |
3c96cb32 | 443 | * Destroy all blkgs associated with @q. |
9f13ef67 | 444 | */ |
3c96cb32 | 445 | static void blkg_destroy_all(struct request_queue *q) |
72e06c25 | 446 | { |
3c798398 | 447 | struct blkcg_gq *blkg, *n; |
72e06c25 | 448 | |
0d945c1f | 449 | spin_lock_irq(&q->queue_lock); |
9f13ef67 | 450 | list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { |
3c798398 | 451 | struct blkcg *blkcg = blkg->blkcg; |
72e06c25 | 452 | |
9f13ef67 TH |
453 | spin_lock(&blkcg->lock); |
454 | blkg_destroy(blkg); | |
455 | spin_unlock(&blkcg->lock); | |
72e06c25 | 456 | } |
6fe810bd TH |
457 | |
458 | q->root_blkg = NULL; | |
0d945c1f | 459 | spin_unlock_irq(&q->queue_lock); |
72e06c25 TH |
460 | } |
461 | ||
182446d0 TH |
462 | static int blkcg_reset_stats(struct cgroup_subsys_state *css, |
463 | struct cftype *cftype, u64 val) | |
303a3acb | 464 | { |
182446d0 | 465 | struct blkcg *blkcg = css_to_blkcg(css); |
3c798398 | 466 | struct blkcg_gq *blkg; |
bc0d6501 | 467 | int i; |
303a3acb | 468 | |
838f13bf | 469 | mutex_lock(&blkcg_pol_mutex); |
303a3acb | 470 | spin_lock_irq(&blkcg->lock); |
997a026c TH |
471 | |
472 | /* | |
473 | * Note that stat reset is racy - it doesn't synchronize against | |
474 | * stat updates. This is a debug feature which shouldn't exist | |
475 | * anyway. If you get hit by a race, retry. | |
476 | */ | |
b67bfe0d | 477 | hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { |
77ea7338 TH |
478 | blkg_rwstat_reset(&blkg->stat_bytes); |
479 | blkg_rwstat_reset(&blkg->stat_ios); | |
480 | ||
8bd435b3 | 481 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
3c798398 | 482 | struct blkcg_policy *pol = blkcg_policy[i]; |
549d3aa8 | 483 | |
a9520cd6 TH |
484 | if (blkg->pd[i] && pol->pd_reset_stats_fn) |
485 | pol->pd_reset_stats_fn(blkg->pd[i]); | |
bc0d6501 | 486 | } |
303a3acb | 487 | } |
f0bdc8cd | 488 | |
303a3acb | 489 | spin_unlock_irq(&blkcg->lock); |
bc0d6501 | 490 | mutex_unlock(&blkcg_pol_mutex); |
303a3acb DS |
491 | return 0; |
492 | } | |
493 | ||
dd165eb3 | 494 | const char *blkg_dev_name(struct blkcg_gq *blkg) |
303a3acb | 495 | { |
d3d32e69 | 496 | /* some drivers (floppy) instantiate a queue w/o disk registered */ |
dc3b17cc JK |
497 | if (blkg->q->backing_dev_info->dev) |
498 | return dev_name(blkg->q->backing_dev_info->dev); | |
d3d32e69 | 499 | return NULL; |
303a3acb DS |
500 | } |
501 | ||
d3d32e69 TH |
502 | /** |
503 | * blkcg_print_blkgs - helper for printing per-blkg data | |
504 | * @sf: seq_file to print to | |
505 | * @blkcg: blkcg of interest | |
506 | * @prfill: fill function to print out a blkg | |
507 | * @pol: policy in question | |
508 | * @data: data to be passed to @prfill | |
509 | * @show_total: to print out sum of prfill return values or not | |
510 | * | |
511 | * This function invokes @prfill on each blkg of @blkcg if pd for the | |
512 | * policy specified by @pol exists. @prfill is invoked with @sf, the | |
810ecfa7 TH |
513 | * policy data and @data and the matching queue lock held. If @show_total |
514 | * is %true, the sum of the return values from @prfill is printed with | |
515 | * "Total" label at the end. | |
d3d32e69 TH |
516 | * |
517 | * This is to be used to construct print functions for | |
518 | * cftype->read_seq_string method. | |
519 | */ | |
3c798398 | 520 | void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg, |
f95a04af TH |
521 | u64 (*prfill)(struct seq_file *, |
522 | struct blkg_policy_data *, int), | |
3c798398 | 523 | const struct blkcg_policy *pol, int data, |
ec399347 | 524 | bool show_total) |
5624a4e4 | 525 | { |
3c798398 | 526 | struct blkcg_gq *blkg; |
d3d32e69 | 527 | u64 total = 0; |
5624a4e4 | 528 | |
810ecfa7 | 529 | rcu_read_lock(); |
ee89f812 | 530 | hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { |
0d945c1f | 531 | spin_lock_irq(&blkg->q->queue_lock); |
a2b1693b | 532 | if (blkcg_policy_enabled(blkg->q, pol)) |
f95a04af | 533 | total += prfill(sf, blkg->pd[pol->plid], data); |
0d945c1f | 534 | spin_unlock_irq(&blkg->q->queue_lock); |
810ecfa7 TH |
535 | } |
536 | rcu_read_unlock(); | |
d3d32e69 TH |
537 | |
538 | if (show_total) | |
539 | seq_printf(sf, "Total %llu\n", (unsigned long long)total); | |
540 | } | |
829fdb50 | 541 | EXPORT_SYMBOL_GPL(blkcg_print_blkgs); |
d3d32e69 TH |
542 | |
543 | /** | |
544 | * __blkg_prfill_u64 - prfill helper for a single u64 value | |
545 | * @sf: seq_file to print to | |
f95a04af | 546 | * @pd: policy private data of interest |
d3d32e69 TH |
547 | * @v: value to print |
548 | * | |
f95a04af | 549 | * Print @v to @sf for the device assocaited with @pd. |
d3d32e69 | 550 | */ |
f95a04af | 551 | u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v) |
d3d32e69 | 552 | { |
f95a04af | 553 | const char *dname = blkg_dev_name(pd->blkg); |
d3d32e69 TH |
554 | |
555 | if (!dname) | |
556 | return 0; | |
557 | ||
558 | seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v); | |
559 | return v; | |
560 | } | |
829fdb50 | 561 | EXPORT_SYMBOL_GPL(__blkg_prfill_u64); |
d3d32e69 TH |
562 | |
563 | /** | |
564 | * __blkg_prfill_rwstat - prfill helper for a blkg_rwstat | |
565 | * @sf: seq_file to print to | |
f95a04af | 566 | * @pd: policy private data of interest |
d3d32e69 TH |
567 | * @rwstat: rwstat to print |
568 | * | |
f95a04af | 569 | * Print @rwstat to @sf for the device assocaited with @pd. |
d3d32e69 | 570 | */ |
f95a04af | 571 | u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, |
7af6fd91 | 572 | const struct blkg_rwstat_sample *rwstat) |
d3d32e69 TH |
573 | { |
574 | static const char *rwstr[] = { | |
575 | [BLKG_RWSTAT_READ] = "Read", | |
576 | [BLKG_RWSTAT_WRITE] = "Write", | |
577 | [BLKG_RWSTAT_SYNC] = "Sync", | |
578 | [BLKG_RWSTAT_ASYNC] = "Async", | |
636620b6 | 579 | [BLKG_RWSTAT_DISCARD] = "Discard", |
d3d32e69 | 580 | }; |
f95a04af | 581 | const char *dname = blkg_dev_name(pd->blkg); |
d3d32e69 TH |
582 | u64 v; |
583 | int i; | |
584 | ||
585 | if (!dname) | |
586 | return 0; | |
587 | ||
588 | for (i = 0; i < BLKG_RWSTAT_NR; i++) | |
589 | seq_printf(sf, "%s %s %llu\n", dname, rwstr[i], | |
7af6fd91 | 590 | rwstat->cnt[i]); |
d3d32e69 | 591 | |
7af6fd91 CH |
592 | v = rwstat->cnt[BLKG_RWSTAT_READ] + |
593 | rwstat->cnt[BLKG_RWSTAT_WRITE] + | |
594 | rwstat->cnt[BLKG_RWSTAT_DISCARD]; | |
595 | seq_printf(sf, "%s Total %llu\n", dname, v); | |
d3d32e69 TH |
596 | return v; |
597 | } | |
b50da39f | 598 | EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat); |
d3d32e69 | 599 | |
5bc4afb1 TH |
600 | /** |
601 | * blkg_prfill_rwstat - prfill callback for blkg_rwstat | |
602 | * @sf: seq_file to print to | |
f95a04af TH |
603 | * @pd: policy private data of interest |
604 | * @off: offset to the blkg_rwstat in @pd | |
5bc4afb1 TH |
605 | * |
606 | * prfill callback for printing a blkg_rwstat. | |
607 | */ | |
f95a04af TH |
608 | u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, |
609 | int off) | |
d3d32e69 | 610 | { |
7af6fd91 | 611 | struct blkg_rwstat_sample rwstat = { }; |
d3d32e69 | 612 | |
5d0b6e48 | 613 | blkg_rwstat_read((void *)pd + off, &rwstat); |
f95a04af | 614 | return __blkg_prfill_rwstat(sf, pd, &rwstat); |
d3d32e69 | 615 | } |
5bc4afb1 | 616 | EXPORT_SYMBOL_GPL(blkg_prfill_rwstat); |
d3d32e69 | 617 | |
77ea7338 TH |
618 | static u64 blkg_prfill_rwstat_field(struct seq_file *sf, |
619 | struct blkg_policy_data *pd, int off) | |
620 | { | |
7af6fd91 | 621 | struct blkg_rwstat_sample rwstat = { }; |
77ea7338 | 622 | |
5d0b6e48 | 623 | blkg_rwstat_read((void *)pd->blkg + off, &rwstat); |
77ea7338 TH |
624 | return __blkg_prfill_rwstat(sf, pd, &rwstat); |
625 | } | |
626 | ||
627 | /** | |
628 | * blkg_print_stat_bytes - seq_show callback for blkg->stat_bytes | |
629 | * @sf: seq_file to print to | |
630 | * @v: unused | |
631 | * | |
632 | * To be used as cftype->seq_show to print blkg->stat_bytes. | |
633 | * cftype->private must be set to the blkcg_policy. | |
634 | */ | |
635 | int blkg_print_stat_bytes(struct seq_file *sf, void *v) | |
636 | { | |
637 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), | |
638 | blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private, | |
639 | offsetof(struct blkcg_gq, stat_bytes), true); | |
640 | return 0; | |
641 | } | |
642 | EXPORT_SYMBOL_GPL(blkg_print_stat_bytes); | |
643 | ||
644 | /** | |
645 | * blkg_print_stat_bytes - seq_show callback for blkg->stat_ios | |
646 | * @sf: seq_file to print to | |
647 | * @v: unused | |
648 | * | |
649 | * To be used as cftype->seq_show to print blkg->stat_ios. cftype->private | |
650 | * must be set to the blkcg_policy. | |
651 | */ | |
652 | int blkg_print_stat_ios(struct seq_file *sf, void *v) | |
653 | { | |
654 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), | |
655 | blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private, | |
656 | offsetof(struct blkcg_gq, stat_ios), true); | |
657 | return 0; | |
658 | } | |
659 | EXPORT_SYMBOL_GPL(blkg_print_stat_ios); | |
660 | ||
661 | static u64 blkg_prfill_rwstat_field_recursive(struct seq_file *sf, | |
662 | struct blkg_policy_data *pd, | |
663 | int off) | |
664 | { | |
7af6fd91 | 665 | struct blkg_rwstat_sample rwstat; |
5d0b6e48 CH |
666 | |
667 | blkg_rwstat_recursive_sum(pd->blkg, NULL, off, &rwstat); | |
77ea7338 TH |
668 | return __blkg_prfill_rwstat(sf, pd, &rwstat); |
669 | } | |
670 | ||
671 | /** | |
672 | * blkg_print_stat_bytes_recursive - recursive version of blkg_print_stat_bytes | |
673 | * @sf: seq_file to print to | |
674 | * @v: unused | |
675 | */ | |
676 | int blkg_print_stat_bytes_recursive(struct seq_file *sf, void *v) | |
677 | { | |
678 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), | |
679 | blkg_prfill_rwstat_field_recursive, | |
680 | (void *)seq_cft(sf)->private, | |
681 | offsetof(struct blkcg_gq, stat_bytes), true); | |
682 | return 0; | |
683 | } | |
684 | EXPORT_SYMBOL_GPL(blkg_print_stat_bytes_recursive); | |
685 | ||
686 | /** | |
687 | * blkg_print_stat_ios_recursive - recursive version of blkg_print_stat_ios | |
688 | * @sf: seq_file to print to | |
689 | * @v: unused | |
690 | */ | |
691 | int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v) | |
692 | { | |
693 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), | |
694 | blkg_prfill_rwstat_field_recursive, | |
695 | (void *)seq_cft(sf)->private, | |
696 | offsetof(struct blkcg_gq, stat_ios), true); | |
697 | return 0; | |
698 | } | |
699 | EXPORT_SYMBOL_GPL(blkg_print_stat_ios_recursive); | |
700 | ||
16b3de66 TH |
701 | /** |
702 | * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat | |
f12c74ca TH |
703 | * @blkg: blkg of interest |
704 | * @pol: blkcg_policy which contains the blkg_rwstat | |
705 | * @off: offset to the blkg_rwstat in blkg_policy_data or @blkg | |
7af6fd91 | 706 | * @sum: blkg_rwstat_sample structure containing the results |
16b3de66 | 707 | * |
f12c74ca TH |
708 | * Collect the blkg_rwstat specified by @blkg, @pol and @off and all its |
709 | * online descendants and their aux counts. The caller must be holding the | |
710 | * queue lock for online tests. | |
711 | * | |
712 | * If @pol is NULL, blkg_rwstat is at @off bytes into @blkg; otherwise, it | |
713 | * is at @off bytes into @blkg's blkg_policy_data of the policy. | |
16b3de66 | 714 | */ |
5d0b6e48 | 715 | void blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, struct blkcg_policy *pol, |
7af6fd91 | 716 | int off, struct blkg_rwstat_sample *sum) |
16b3de66 | 717 | { |
16b3de66 | 718 | struct blkcg_gq *pos_blkg; |
492eb21b | 719 | struct cgroup_subsys_state *pos_css; |
239eeb08 | 720 | unsigned int i; |
16b3de66 | 721 | |
0d945c1f | 722 | lockdep_assert_held(&blkg->q->queue_lock); |
16b3de66 | 723 | |
16b3de66 | 724 | rcu_read_lock(); |
f12c74ca | 725 | blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) { |
3a7faead | 726 | struct blkg_rwstat *rwstat; |
16b3de66 TH |
727 | |
728 | if (!pos_blkg->online) | |
729 | continue; | |
730 | ||
f12c74ca TH |
731 | if (pol) |
732 | rwstat = (void *)blkg_to_pd(pos_blkg, pol) + off; | |
733 | else | |
734 | rwstat = (void *)pos_blkg + off; | |
735 | ||
16b3de66 | 736 | for (i = 0; i < BLKG_RWSTAT_NR; i++) |
7af6fd91 | 737 | sum->cnt[i] = blkg_rwstat_read_counter(rwstat, i); |
16b3de66 TH |
738 | } |
739 | rcu_read_unlock(); | |
16b3de66 TH |
740 | } |
741 | EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum); | |
742 | ||
457e490f TE |
743 | /* Performs queue bypass and policy enabled checks then looks up blkg. */ |
744 | static struct blkcg_gq *blkg_lookup_check(struct blkcg *blkcg, | |
745 | const struct blkcg_policy *pol, | |
746 | struct request_queue *q) | |
747 | { | |
748 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
0d945c1f | 749 | lockdep_assert_held(&q->queue_lock); |
457e490f TE |
750 | |
751 | if (!blkcg_policy_enabled(q, pol)) | |
752 | return ERR_PTR(-EOPNOTSUPP); | |
457e490f TE |
753 | return __blkg_lookup(blkcg, q, true /* update_hint */); |
754 | } | |
755 | ||
3a8b31d3 TH |
756 | /** |
757 | * blkg_conf_prep - parse and prepare for per-blkg config update | |
758 | * @blkcg: target block cgroup | |
da8b0662 | 759 | * @pol: target policy |
3a8b31d3 TH |
760 | * @input: input string |
761 | * @ctx: blkg_conf_ctx to be filled | |
762 | * | |
763 | * Parse per-blkg config update from @input and initialize @ctx with the | |
36aa9e5f TH |
764 | * result. @ctx->blkg points to the blkg to be updated and @ctx->body the |
765 | * part of @input following MAJ:MIN. This function returns with RCU read | |
766 | * lock and queue lock held and must be paired with blkg_conf_finish(). | |
3a8b31d3 | 767 | */ |
3c798398 | 768 | int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, |
36aa9e5f | 769 | char *input, struct blkg_conf_ctx *ctx) |
0d945c1f | 770 | __acquires(rcu) __acquires(&disk->queue->queue_lock) |
34d0f179 | 771 | { |
3a8b31d3 | 772 | struct gendisk *disk; |
457e490f | 773 | struct request_queue *q; |
3c798398 | 774 | struct blkcg_gq *blkg; |
726fa694 | 775 | unsigned int major, minor; |
36aa9e5f TH |
776 | int key_len, part, ret; |
777 | char *body; | |
34d0f179 | 778 | |
36aa9e5f | 779 | if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2) |
726fa694 | 780 | return -EINVAL; |
3a8b31d3 | 781 | |
36aa9e5f TH |
782 | body = input + key_len; |
783 | if (!isspace(*body)) | |
784 | return -EINVAL; | |
785 | body = skip_spaces(body); | |
786 | ||
726fa694 | 787 | disk = get_gendisk(MKDEV(major, minor), &part); |
5f6c2d2b | 788 | if (!disk) |
20386ce0 | 789 | return -ENODEV; |
5f6c2d2b | 790 | if (part) { |
457e490f TE |
791 | ret = -ENODEV; |
792 | goto fail; | |
5f6c2d2b | 793 | } |
e56da7e2 | 794 | |
457e490f | 795 | q = disk->queue; |
da8b0662 | 796 | |
457e490f | 797 | rcu_read_lock(); |
0d945c1f | 798 | spin_lock_irq(&q->queue_lock); |
e56da7e2 | 799 | |
457e490f | 800 | blkg = blkg_lookup_check(blkcg, pol, q); |
4bfd482e TH |
801 | if (IS_ERR(blkg)) { |
802 | ret = PTR_ERR(blkg); | |
457e490f TE |
803 | goto fail_unlock; |
804 | } | |
805 | ||
806 | if (blkg) | |
807 | goto success; | |
808 | ||
809 | /* | |
810 | * Create blkgs walking down from blkcg_root to @blkcg, so that all | |
811 | * non-root blkgs have access to their parents. | |
812 | */ | |
813 | while (true) { | |
814 | struct blkcg *pos = blkcg; | |
815 | struct blkcg *parent; | |
816 | struct blkcg_gq *new_blkg; | |
817 | ||
818 | parent = blkcg_parent(blkcg); | |
819 | while (parent && !__blkg_lookup(parent, q, false)) { | |
820 | pos = parent; | |
821 | parent = blkcg_parent(parent); | |
822 | } | |
823 | ||
824 | /* Drop locks to do new blkg allocation with GFP_KERNEL. */ | |
0d945c1f | 825 | spin_unlock_irq(&q->queue_lock); |
3a8b31d3 | 826 | rcu_read_unlock(); |
457e490f TE |
827 | |
828 | new_blkg = blkg_alloc(pos, q, GFP_KERNEL); | |
829 | if (unlikely(!new_blkg)) { | |
830 | ret = -ENOMEM; | |
831 | goto fail; | |
7702e8f4 | 832 | } |
3a8b31d3 | 833 | |
457e490f | 834 | rcu_read_lock(); |
0d945c1f | 835 | spin_lock_irq(&q->queue_lock); |
457e490f TE |
836 | |
837 | blkg = blkg_lookup_check(pos, pol, q); | |
838 | if (IS_ERR(blkg)) { | |
839 | ret = PTR_ERR(blkg); | |
840 | goto fail_unlock; | |
841 | } | |
842 | ||
843 | if (blkg) { | |
844 | blkg_free(new_blkg); | |
845 | } else { | |
846 | blkg = blkg_create(pos, q, new_blkg); | |
98d669b4 | 847 | if (IS_ERR(blkg)) { |
457e490f TE |
848 | ret = PTR_ERR(blkg); |
849 | goto fail_unlock; | |
850 | } | |
851 | } | |
852 | ||
853 | if (pos == blkcg) | |
854 | goto success; | |
855 | } | |
856 | success: | |
3a8b31d3 TH |
857 | ctx->disk = disk; |
858 | ctx->blkg = blkg; | |
36aa9e5f | 859 | ctx->body = body; |
726fa694 | 860 | return 0; |
457e490f TE |
861 | |
862 | fail_unlock: | |
0d945c1f | 863 | spin_unlock_irq(&q->queue_lock); |
457e490f TE |
864 | rcu_read_unlock(); |
865 | fail: | |
9df6c299 | 866 | put_disk_and_module(disk); |
457e490f TE |
867 | /* |
868 | * If queue was bypassing, we should retry. Do so after a | |
869 | * short msleep(). It isn't strictly necessary but queue | |
870 | * can be bypassing for some time and it's always nice to | |
871 | * avoid busy looping. | |
872 | */ | |
873 | if (ret == -EBUSY) { | |
874 | msleep(10); | |
875 | ret = restart_syscall(); | |
876 | } | |
877 | return ret; | |
34d0f179 GJ |
878 | } |
879 | ||
3a8b31d3 TH |
880 | /** |
881 | * blkg_conf_finish - finish up per-blkg config update | |
882 | * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep() | |
883 | * | |
884 | * Finish up after per-blkg config update. This function must be paired | |
885 | * with blkg_conf_prep(). | |
886 | */ | |
829fdb50 | 887 | void blkg_conf_finish(struct blkg_conf_ctx *ctx) |
0d945c1f | 888 | __releases(&ctx->disk->queue->queue_lock) __releases(rcu) |
34d0f179 | 889 | { |
0d945c1f | 890 | spin_unlock_irq(&ctx->disk->queue->queue_lock); |
3a8b31d3 | 891 | rcu_read_unlock(); |
9df6c299 | 892 | put_disk_and_module(ctx->disk); |
34d0f179 GJ |
893 | } |
894 | ||
2ee867dc TH |
895 | static int blkcg_print_stat(struct seq_file *sf, void *v) |
896 | { | |
897 | struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); | |
898 | struct blkcg_gq *blkg; | |
899 | ||
900 | rcu_read_lock(); | |
901 | ||
902 | hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { | |
903 | const char *dname; | |
903d23f0 | 904 | char *buf; |
7af6fd91 | 905 | struct blkg_rwstat_sample rwstat; |
636620b6 | 906 | u64 rbytes, wbytes, rios, wios, dbytes, dios; |
903d23f0 JB |
907 | size_t size = seq_get_buf(sf, &buf), off = 0; |
908 | int i; | |
909 | bool has_stats = false; | |
2ee867dc TH |
910 | |
911 | dname = blkg_dev_name(blkg); | |
912 | if (!dname) | |
913 | continue; | |
914 | ||
903d23f0 JB |
915 | /* |
916 | * Hooray string manipulation, count is the size written NOT | |
917 | * INCLUDING THE \0, so size is now count+1 less than what we | |
918 | * had before, but we want to start writing the next bit from | |
919 | * the \0 so we only add count to buf. | |
920 | */ | |
921 | off += scnprintf(buf+off, size-off, "%s ", dname); | |
922 | ||
0d945c1f | 923 | spin_lock_irq(&blkg->q->queue_lock); |
2ee867dc | 924 | |
5d0b6e48 CH |
925 | blkg_rwstat_recursive_sum(blkg, NULL, |
926 | offsetof(struct blkcg_gq, stat_bytes), &rwstat); | |
7af6fd91 CH |
927 | rbytes = rwstat.cnt[BLKG_RWSTAT_READ]; |
928 | wbytes = rwstat.cnt[BLKG_RWSTAT_WRITE]; | |
929 | dbytes = rwstat.cnt[BLKG_RWSTAT_DISCARD]; | |
2ee867dc | 930 | |
5d0b6e48 CH |
931 | blkg_rwstat_recursive_sum(blkg, NULL, |
932 | offsetof(struct blkcg_gq, stat_ios), &rwstat); | |
7af6fd91 CH |
933 | rios = rwstat.cnt[BLKG_RWSTAT_READ]; |
934 | wios = rwstat.cnt[BLKG_RWSTAT_WRITE]; | |
935 | dios = rwstat.cnt[BLKG_RWSTAT_DISCARD]; | |
2ee867dc | 936 | |
0d945c1f | 937 | spin_unlock_irq(&blkg->q->queue_lock); |
2ee867dc | 938 | |
903d23f0 JB |
939 | if (rbytes || wbytes || rios || wios) { |
940 | has_stats = true; | |
941 | off += scnprintf(buf+off, size-off, | |
636620b6 TH |
942 | "rbytes=%llu wbytes=%llu rios=%llu wios=%llu dbytes=%llu dios=%llu", |
943 | rbytes, wbytes, rios, wios, | |
944 | dbytes, dios); | |
903d23f0 JB |
945 | } |
946 | ||
947 | if (!blkcg_debug_stats) | |
948 | goto next; | |
949 | ||
d09d8df3 JB |
950 | if (atomic_read(&blkg->use_delay)) { |
951 | has_stats = true; | |
952 | off += scnprintf(buf+off, size-off, | |
953 | " use_delay=%d delay_nsec=%llu", | |
954 | atomic_read(&blkg->use_delay), | |
955 | (unsigned long long)atomic64_read(&blkg->delay_nsec)); | |
956 | } | |
957 | ||
903d23f0 JB |
958 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
959 | struct blkcg_policy *pol = blkcg_policy[i]; | |
960 | size_t written; | |
961 | ||
962 | if (!blkg->pd[i] || !pol->pd_stat_fn) | |
963 | continue; | |
964 | ||
965 | written = pol->pd_stat_fn(blkg->pd[i], buf+off, size-off); | |
966 | if (written) | |
967 | has_stats = true; | |
968 | off += written; | |
969 | } | |
970 | next: | |
971 | if (has_stats) { | |
f539da82 TH |
972 | if (off < size - 1) { |
973 | off += scnprintf(buf+off, size-off, "\n"); | |
974 | seq_commit(sf, off); | |
975 | } else { | |
976 | seq_commit(sf, -1); | |
977 | } | |
903d23f0 | 978 | } |
2ee867dc TH |
979 | } |
980 | ||
981 | rcu_read_unlock(); | |
982 | return 0; | |
983 | } | |
984 | ||
e1f3b941 | 985 | static struct cftype blkcg_files[] = { |
2ee867dc TH |
986 | { |
987 | .name = "stat", | |
ca0752c5 | 988 | .flags = CFTYPE_NOT_ON_ROOT, |
2ee867dc TH |
989 | .seq_show = blkcg_print_stat, |
990 | }, | |
991 | { } /* terminate */ | |
992 | }; | |
993 | ||
e1f3b941 | 994 | static struct cftype blkcg_legacy_files[] = { |
84c124da DS |
995 | { |
996 | .name = "reset_stats", | |
3c798398 | 997 | .write_u64 = blkcg_reset_stats, |
22084190 | 998 | }, |
4baf6e33 | 999 | { } /* terminate */ |
31e4c28d VG |
1000 | }; |
1001 | ||
59b57717 DZF |
1002 | /* |
1003 | * blkcg destruction is a three-stage process. | |
1004 | * | |
1005 | * 1. Destruction starts. The blkcg_css_offline() callback is invoked | |
1006 | * which offlines writeback. Here we tie the next stage of blkg destruction | |
1007 | * to the completion of writeback associated with the blkcg. This lets us | |
1008 | * avoid punting potentially large amounts of outstanding writeback to root | |
1009 | * while maintaining any ongoing policies. The next stage is triggered when | |
1010 | * the nr_cgwbs count goes to zero. | |
1011 | * | |
1012 | * 2. When the nr_cgwbs count goes to zero, blkcg_destroy_blkgs() is called | |
1013 | * and handles the destruction of blkgs. Here the css reference held by | |
1014 | * the blkg is put back eventually allowing blkcg_css_free() to be called. | |
1015 | * This work may occur in cgwb_release_workfn() on the cgwb_release | |
1016 | * workqueue. Any submitted ios that fail to get the blkg ref will be | |
1017 | * punted to the root_blkg. | |
1018 | * | |
1019 | * 3. Once the blkcg ref count goes to zero, blkcg_css_free() is called. | |
1020 | * This finally frees the blkcg. | |
1021 | */ | |
1022 | ||
9f13ef67 | 1023 | /** |
92fb9748 | 1024 | * blkcg_css_offline - cgroup css_offline callback |
eb95419b | 1025 | * @css: css of interest |
9f13ef67 | 1026 | * |
59b57717 DZF |
1027 | * This function is called when @css is about to go away. Here the cgwbs are |
1028 | * offlined first and only once writeback associated with the blkcg has | |
1029 | * finished do we start step 2 (see above). | |
9f13ef67 | 1030 | */ |
eb95419b | 1031 | static void blkcg_css_offline(struct cgroup_subsys_state *css) |
31e4c28d | 1032 | { |
eb95419b | 1033 | struct blkcg *blkcg = css_to_blkcg(css); |
b1c35769 | 1034 | |
59b57717 DZF |
1035 | /* this prevents anyone from attaching or migrating to this blkcg */ |
1036 | wb_blkcg_offline(blkcg); | |
1037 | ||
1038 | /* put the base cgwb reference allowing step 2 to be triggered */ | |
1039 | blkcg_cgwb_put(blkcg); | |
1040 | } | |
1041 | ||
1042 | /** | |
1043 | * blkcg_destroy_blkgs - responsible for shooting down blkgs | |
1044 | * @blkcg: blkcg of interest | |
1045 | * | |
1046 | * blkgs should be removed while holding both q and blkcg locks. As blkcg lock | |
1047 | * is nested inside q lock, this function performs reverse double lock dancing. | |
1048 | * Destroying the blkgs releases the reference held on the blkcg's css allowing | |
1049 | * blkcg_css_free to eventually be called. | |
1050 | * | |
1051 | * This is the blkcg counterpart of ioc_release_fn(). | |
1052 | */ | |
1053 | void blkcg_destroy_blkgs(struct blkcg *blkcg) | |
1054 | { | |
9f13ef67 | 1055 | spin_lock_irq(&blkcg->lock); |
7ee9c562 | 1056 | |
4c699480 JQ |
1057 | while (!hlist_empty(&blkcg->blkg_list)) { |
1058 | struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first, | |
6b065462 | 1059 | struct blkcg_gq, blkcg_node); |
4c699480 JQ |
1060 | struct request_queue *q = blkg->q; |
1061 | ||
0d945c1f | 1062 | if (spin_trylock(&q->queue_lock)) { |
4c699480 | 1063 | blkg_destroy(blkg); |
0d945c1f | 1064 | spin_unlock(&q->queue_lock); |
4c699480 JQ |
1065 | } else { |
1066 | spin_unlock_irq(&blkcg->lock); | |
1067 | cpu_relax(); | |
1068 | spin_lock_irq(&blkcg->lock); | |
1069 | } | |
1070 | } | |
6b065462 | 1071 | |
4c699480 JQ |
1072 | spin_unlock_irq(&blkcg->lock); |
1073 | } | |
1074 | ||
eb95419b | 1075 | static void blkcg_css_free(struct cgroup_subsys_state *css) |
7ee9c562 | 1076 | { |
eb95419b | 1077 | struct blkcg *blkcg = css_to_blkcg(css); |
bc915e61 | 1078 | int i; |
7ee9c562 | 1079 | |
7876f930 | 1080 | mutex_lock(&blkcg_pol_mutex); |
e4a9bde9 | 1081 | |
7876f930 | 1082 | list_del(&blkcg->all_blkcgs_node); |
7876f930 | 1083 | |
bc915e61 | 1084 | for (i = 0; i < BLKCG_MAX_POLS; i++) |
e4a9bde9 TH |
1085 | if (blkcg->cpd[i]) |
1086 | blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]); | |
1087 | ||
1088 | mutex_unlock(&blkcg_pol_mutex); | |
1089 | ||
bc915e61 | 1090 | kfree(blkcg); |
31e4c28d VG |
1091 | } |
1092 | ||
eb95419b TH |
1093 | static struct cgroup_subsys_state * |
1094 | blkcg_css_alloc(struct cgroup_subsys_state *parent_css) | |
31e4c28d | 1095 | { |
3c798398 | 1096 | struct blkcg *blkcg; |
e48453c3 AA |
1097 | struct cgroup_subsys_state *ret; |
1098 | int i; | |
31e4c28d | 1099 | |
7876f930 TH |
1100 | mutex_lock(&blkcg_pol_mutex); |
1101 | ||
eb95419b | 1102 | if (!parent_css) { |
3c798398 | 1103 | blkcg = &blkcg_root; |
bc915e61 TH |
1104 | } else { |
1105 | blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); | |
1106 | if (!blkcg) { | |
1107 | ret = ERR_PTR(-ENOMEM); | |
4c18c9e9 | 1108 | goto unlock; |
bc915e61 | 1109 | } |
e48453c3 AA |
1110 | } |
1111 | ||
1112 | for (i = 0; i < BLKCG_MAX_POLS ; i++) { | |
1113 | struct blkcg_policy *pol = blkcg_policy[i]; | |
1114 | struct blkcg_policy_data *cpd; | |
1115 | ||
1116 | /* | |
1117 | * If the policy hasn't been attached yet, wait for it | |
1118 | * to be attached before doing anything else. Otherwise, | |
1119 | * check if the policy requires any specific per-cgroup | |
1120 | * data: if it does, allocate and initialize it. | |
1121 | */ | |
e4a9bde9 | 1122 | if (!pol || !pol->cpd_alloc_fn) |
e48453c3 AA |
1123 | continue; |
1124 | ||
e4a9bde9 | 1125 | cpd = pol->cpd_alloc_fn(GFP_KERNEL); |
e48453c3 AA |
1126 | if (!cpd) { |
1127 | ret = ERR_PTR(-ENOMEM); | |
1128 | goto free_pd_blkcg; | |
1129 | } | |
81437648 TH |
1130 | blkcg->cpd[i] = cpd; |
1131 | cpd->blkcg = blkcg; | |
e48453c3 | 1132 | cpd->plid = i; |
e4a9bde9 TH |
1133 | if (pol->cpd_init_fn) |
1134 | pol->cpd_init_fn(cpd); | |
e48453c3 | 1135 | } |
31e4c28d | 1136 | |
31e4c28d | 1137 | spin_lock_init(&blkcg->lock); |
e00f4f4d | 1138 | INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT | __GFP_NOWARN); |
31e4c28d | 1139 | INIT_HLIST_HEAD(&blkcg->blkg_list); |
52ebea74 TH |
1140 | #ifdef CONFIG_CGROUP_WRITEBACK |
1141 | INIT_LIST_HEAD(&blkcg->cgwb_list); | |
59b57717 | 1142 | refcount_set(&blkcg->cgwb_refcnt, 1); |
52ebea74 | 1143 | #endif |
7876f930 TH |
1144 | list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs); |
1145 | ||
1146 | mutex_unlock(&blkcg_pol_mutex); | |
31e4c28d | 1147 | return &blkcg->css; |
e48453c3 AA |
1148 | |
1149 | free_pd_blkcg: | |
1150 | for (i--; i >= 0; i--) | |
e4a9bde9 TH |
1151 | if (blkcg->cpd[i]) |
1152 | blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]); | |
4c18c9e9 | 1153 | |
1154 | if (blkcg != &blkcg_root) | |
1155 | kfree(blkcg); | |
1156 | unlock: | |
7876f930 | 1157 | mutex_unlock(&blkcg_pol_mutex); |
e48453c3 | 1158 | return ret; |
31e4c28d VG |
1159 | } |
1160 | ||
5efd6113 TH |
1161 | /** |
1162 | * blkcg_init_queue - initialize blkcg part of request queue | |
1163 | * @q: request_queue to initialize | |
1164 | * | |
1165 | * Called from blk_alloc_queue_node(). Responsible for initializing blkcg | |
1166 | * part of new request_queue @q. | |
1167 | * | |
1168 | * RETURNS: | |
1169 | * 0 on success, -errno on failure. | |
1170 | */ | |
1171 | int blkcg_init_queue(struct request_queue *q) | |
1172 | { | |
d708f0d5 JA |
1173 | struct blkcg_gq *new_blkg, *blkg; |
1174 | bool preloaded; | |
ec13b1d6 TH |
1175 | int ret; |
1176 | ||
d708f0d5 JA |
1177 | new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL); |
1178 | if (!new_blkg) | |
1179 | return -ENOMEM; | |
1180 | ||
1181 | preloaded = !radix_tree_preload(GFP_KERNEL); | |
1182 | ||
bea54883 | 1183 | /* Make sure the root blkg exists. */ |
ec13b1d6 | 1184 | rcu_read_lock(); |
0d945c1f | 1185 | spin_lock_irq(&q->queue_lock); |
d708f0d5 | 1186 | blkg = blkg_create(&blkcg_root, q, new_blkg); |
901932a3 JB |
1187 | if (IS_ERR(blkg)) |
1188 | goto err_unlock; | |
1189 | q->root_blkg = blkg; | |
0d945c1f | 1190 | spin_unlock_irq(&q->queue_lock); |
ec13b1d6 TH |
1191 | rcu_read_unlock(); |
1192 | ||
d708f0d5 JA |
1193 | if (preloaded) |
1194 | radix_tree_preload_end(); | |
1195 | ||
d7067512 | 1196 | ret = blk_iolatency_init(q); |
04be60b5 CH |
1197 | if (ret) |
1198 | goto err_destroy_all; | |
d7067512 | 1199 | |
ec13b1d6 | 1200 | ret = blk_throtl_init(q); |
04be60b5 CH |
1201 | if (ret) |
1202 | goto err_destroy_all; | |
1203 | return 0; | |
901932a3 | 1204 | |
04be60b5 | 1205 | err_destroy_all: |
04be60b5 | 1206 | blkg_destroy_all(q); |
04be60b5 | 1207 | return ret; |
901932a3 | 1208 | err_unlock: |
0d945c1f | 1209 | spin_unlock_irq(&q->queue_lock); |
901932a3 JB |
1210 | rcu_read_unlock(); |
1211 | if (preloaded) | |
1212 | radix_tree_preload_end(); | |
1213 | return PTR_ERR(blkg); | |
5efd6113 TH |
1214 | } |
1215 | ||
1216 | /** | |
1217 | * blkcg_drain_queue - drain blkcg part of request_queue | |
1218 | * @q: request_queue to drain | |
1219 | * | |
1220 | * Called from blk_drain_queue(). Responsible for draining blkcg part. | |
1221 | */ | |
1222 | void blkcg_drain_queue(struct request_queue *q) | |
1223 | { | |
0d945c1f | 1224 | lockdep_assert_held(&q->queue_lock); |
5efd6113 | 1225 | |
0b462c89 TH |
1226 | /* |
1227 | * @q could be exiting and already have destroyed all blkgs as | |
1228 | * indicated by NULL root_blkg. If so, don't confuse policies. | |
1229 | */ | |
1230 | if (!q->root_blkg) | |
1231 | return; | |
1232 | ||
5efd6113 TH |
1233 | blk_throtl_drain(q); |
1234 | } | |
1235 | ||
1236 | /** | |
1237 | * blkcg_exit_queue - exit and release blkcg part of request_queue | |
1238 | * @q: request_queue being released | |
1239 | * | |
7585d508 | 1240 | * Called from blk_exit_queue(). Responsible for exiting blkcg part. |
5efd6113 TH |
1241 | */ |
1242 | void blkcg_exit_queue(struct request_queue *q) | |
1243 | { | |
3c96cb32 | 1244 | blkg_destroy_all(q); |
5efd6113 TH |
1245 | blk_throtl_exit(q); |
1246 | } | |
1247 | ||
31e4c28d VG |
1248 | /* |
1249 | * We cannot support shared io contexts, as we have no mean to support | |
1250 | * two tasks with the same ioc in two different groups without major rework | |
1251 | * of the main cic data structures. For now we allow a task to change | |
1252 | * its cgroup only if it's the only owner of its ioc. | |
1253 | */ | |
1f7dd3e5 | 1254 | static int blkcg_can_attach(struct cgroup_taskset *tset) |
31e4c28d | 1255 | { |
bb9d97b6 | 1256 | struct task_struct *task; |
1f7dd3e5 | 1257 | struct cgroup_subsys_state *dst_css; |
31e4c28d VG |
1258 | struct io_context *ioc; |
1259 | int ret = 0; | |
1260 | ||
1261 | /* task_lock() is needed to avoid races with exit_io_context() */ | |
1f7dd3e5 | 1262 | cgroup_taskset_for_each(task, dst_css, tset) { |
bb9d97b6 TH |
1263 | task_lock(task); |
1264 | ioc = task->io_context; | |
1265 | if (ioc && atomic_read(&ioc->nr_tasks) > 1) | |
1266 | ret = -EINVAL; | |
1267 | task_unlock(task); | |
1268 | if (ret) | |
1269 | break; | |
1270 | } | |
31e4c28d VG |
1271 | return ret; |
1272 | } | |
1273 | ||
69d7fde5 TH |
1274 | static void blkcg_bind(struct cgroup_subsys_state *root_css) |
1275 | { | |
1276 | int i; | |
1277 | ||
1278 | mutex_lock(&blkcg_pol_mutex); | |
1279 | ||
1280 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
1281 | struct blkcg_policy *pol = blkcg_policy[i]; | |
1282 | struct blkcg *blkcg; | |
1283 | ||
1284 | if (!pol || !pol->cpd_bind_fn) | |
1285 | continue; | |
1286 | ||
1287 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) | |
1288 | if (blkcg->cpd[pol->plid]) | |
1289 | pol->cpd_bind_fn(blkcg->cpd[pol->plid]); | |
1290 | } | |
1291 | mutex_unlock(&blkcg_pol_mutex); | |
1292 | } | |
1293 | ||
d09d8df3 JB |
1294 | static void blkcg_exit(struct task_struct *tsk) |
1295 | { | |
1296 | if (tsk->throttle_queue) | |
1297 | blk_put_queue(tsk->throttle_queue); | |
1298 | tsk->throttle_queue = NULL; | |
1299 | } | |
1300 | ||
c165b3e3 | 1301 | struct cgroup_subsys io_cgrp_subsys = { |
92fb9748 TH |
1302 | .css_alloc = blkcg_css_alloc, |
1303 | .css_offline = blkcg_css_offline, | |
1304 | .css_free = blkcg_css_free, | |
3c798398 | 1305 | .can_attach = blkcg_can_attach, |
69d7fde5 | 1306 | .bind = blkcg_bind, |
2ee867dc | 1307 | .dfl_cftypes = blkcg_files, |
880f50e2 | 1308 | .legacy_cftypes = blkcg_legacy_files, |
c165b3e3 | 1309 | .legacy_name = "blkio", |
d09d8df3 | 1310 | .exit = blkcg_exit, |
1ced953b TH |
1311 | #ifdef CONFIG_MEMCG |
1312 | /* | |
1313 | * This ensures that, if available, memcg is automatically enabled | |
1314 | * together on the default hierarchy so that the owner cgroup can | |
1315 | * be retrieved from writeback pages. | |
1316 | */ | |
1317 | .depends_on = 1 << memory_cgrp_id, | |
1318 | #endif | |
676f7c8f | 1319 | }; |
c165b3e3 | 1320 | EXPORT_SYMBOL_GPL(io_cgrp_subsys); |
676f7c8f | 1321 | |
a2b1693b TH |
1322 | /** |
1323 | * blkcg_activate_policy - activate a blkcg policy on a request_queue | |
1324 | * @q: request_queue of interest | |
1325 | * @pol: blkcg policy to activate | |
1326 | * | |
1327 | * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through | |
1328 | * bypass mode to populate its blkgs with policy_data for @pol. | |
1329 | * | |
1330 | * Activation happens with @q bypassed, so nobody would be accessing blkgs | |
1331 | * from IO path. Update of each blkg is protected by both queue and blkcg | |
1332 | * locks so that holding either lock and testing blkcg_policy_enabled() is | |
1333 | * always enough for dereferencing policy data. | |
1334 | * | |
1335 | * The caller is responsible for synchronizing [de]activations and policy | |
1336 | * [un]registerations. Returns 0 on success, -errno on failure. | |
1337 | */ | |
1338 | int blkcg_activate_policy(struct request_queue *q, | |
3c798398 | 1339 | const struct blkcg_policy *pol) |
a2b1693b | 1340 | { |
4c55f4f9 | 1341 | struct blkg_policy_data *pd_prealloc = NULL; |
ec13b1d6 | 1342 | struct blkcg_gq *blkg; |
4c55f4f9 | 1343 | int ret; |
a2b1693b TH |
1344 | |
1345 | if (blkcg_policy_enabled(q, pol)) | |
1346 | return 0; | |
1347 | ||
344e9ffc | 1348 | if (queue_is_mq(q)) |
bd166ef1 | 1349 | blk_mq_freeze_queue(q); |
4c55f4f9 TH |
1350 | pd_prealloc: |
1351 | if (!pd_prealloc) { | |
001bea73 | 1352 | pd_prealloc = pol->pd_alloc_fn(GFP_KERNEL, q->node); |
4c55f4f9 | 1353 | if (!pd_prealloc) { |
a2b1693b | 1354 | ret = -ENOMEM; |
4c55f4f9 | 1355 | goto out_bypass_end; |
a2b1693b | 1356 | } |
a2b1693b TH |
1357 | } |
1358 | ||
0d945c1f | 1359 | spin_lock_irq(&q->queue_lock); |
a2b1693b | 1360 | |
71c81407 TH |
1361 | /* blkg_list is pushed at the head, reverse walk to init parents first */ |
1362 | list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) { | |
4c55f4f9 TH |
1363 | struct blkg_policy_data *pd; |
1364 | ||
1365 | if (blkg->pd[pol->plid]) | |
1366 | continue; | |
a2b1693b | 1367 | |
e00f4f4d | 1368 | pd = pol->pd_alloc_fn(GFP_NOWAIT | __GFP_NOWARN, q->node); |
4c55f4f9 TH |
1369 | if (!pd) |
1370 | swap(pd, pd_prealloc); | |
1371 | if (!pd) { | |
0d945c1f | 1372 | spin_unlock_irq(&q->queue_lock); |
4c55f4f9 TH |
1373 | goto pd_prealloc; |
1374 | } | |
a2b1693b TH |
1375 | |
1376 | blkg->pd[pol->plid] = pd; | |
1377 | pd->blkg = blkg; | |
b276a876 | 1378 | pd->plid = pol->plid; |
3e418710 | 1379 | if (pol->pd_init_fn) |
a9520cd6 | 1380 | pol->pd_init_fn(pd); |
a2b1693b TH |
1381 | } |
1382 | ||
1383 | __set_bit(pol->plid, q->blkcg_pols); | |
1384 | ret = 0; | |
4c55f4f9 | 1385 | |
0d945c1f | 1386 | spin_unlock_irq(&q->queue_lock); |
4c55f4f9 | 1387 | out_bypass_end: |
344e9ffc | 1388 | if (queue_is_mq(q)) |
bd166ef1 | 1389 | blk_mq_unfreeze_queue(q); |
001bea73 TH |
1390 | if (pd_prealloc) |
1391 | pol->pd_free_fn(pd_prealloc); | |
a2b1693b TH |
1392 | return ret; |
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) { | |
001bea73 | 1420 | if (blkg->pd[pol->plid]) { |
6b065462 | 1421 | if (pol->pd_offline_fn) |
a9520cd6 | 1422 | pol->pd_offline_fn(blkg->pd[pol->plid]); |
001bea73 TH |
1423 | pol->pd_free_fn(blkg->pd[pol->plid]); |
1424 | blkg->pd[pol->plid] = NULL; | |
1425 | } | |
a2b1693b TH |
1426 | } |
1427 | ||
0d945c1f | 1428 | spin_unlock_irq(&q->queue_lock); |
bd166ef1 | 1429 | |
344e9ffc | 1430 | if (queue_is_mq(q)) |
bd166ef1 | 1431 | blk_mq_unfreeze_queue(q); |
a2b1693b TH |
1432 | } |
1433 | EXPORT_SYMBOL_GPL(blkcg_deactivate_policy); | |
1434 | ||
8bd435b3 | 1435 | /** |
3c798398 TH |
1436 | * blkcg_policy_register - register a blkcg policy |
1437 | * @pol: blkcg policy to register | |
8bd435b3 | 1438 | * |
3c798398 TH |
1439 | * Register @pol with blkcg core. Might sleep and @pol may be modified on |
1440 | * successful registration. Returns 0 on success and -errno on failure. | |
8bd435b3 | 1441 | */ |
d5bf0291 | 1442 | int blkcg_policy_register(struct blkcg_policy *pol) |
3e252066 | 1443 | { |
06b285bd | 1444 | struct blkcg *blkcg; |
8bd435b3 | 1445 | int i, ret; |
e8989fae | 1446 | |
838f13bf | 1447 | mutex_lock(&blkcg_pol_register_mutex); |
bc0d6501 TH |
1448 | mutex_lock(&blkcg_pol_mutex); |
1449 | ||
8bd435b3 TH |
1450 | /* find an empty slot */ |
1451 | ret = -ENOSPC; | |
1452 | for (i = 0; i < BLKCG_MAX_POLS; i++) | |
3c798398 | 1453 | if (!blkcg_policy[i]) |
8bd435b3 | 1454 | break; |
01c5f85a JA |
1455 | if (i >= BLKCG_MAX_POLS) { |
1456 | pr_warn("blkcg_policy_register: BLKCG_MAX_POLS too small\n"); | |
838f13bf | 1457 | goto err_unlock; |
01c5f85a | 1458 | } |
035d10b2 | 1459 | |
e8401073 | 1460 | /* Make sure cpd/pd_alloc_fn and cpd/pd_free_fn in pairs */ |
1461 | if ((!pol->cpd_alloc_fn ^ !pol->cpd_free_fn) || | |
1462 | (!pol->pd_alloc_fn ^ !pol->pd_free_fn)) | |
1463 | goto err_unlock; | |
1464 | ||
06b285bd | 1465 | /* register @pol */ |
3c798398 | 1466 | pol->plid = i; |
06b285bd TH |
1467 | blkcg_policy[pol->plid] = pol; |
1468 | ||
1469 | /* allocate and install cpd's */ | |
e4a9bde9 | 1470 | if (pol->cpd_alloc_fn) { |
06b285bd TH |
1471 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
1472 | struct blkcg_policy_data *cpd; | |
1473 | ||
e4a9bde9 | 1474 | cpd = pol->cpd_alloc_fn(GFP_KERNEL); |
bbb427e3 | 1475 | if (!cpd) |
06b285bd | 1476 | goto err_free_cpds; |
06b285bd | 1477 | |
81437648 TH |
1478 | blkcg->cpd[pol->plid] = cpd; |
1479 | cpd->blkcg = blkcg; | |
06b285bd | 1480 | cpd->plid = pol->plid; |
81437648 | 1481 | pol->cpd_init_fn(cpd); |
06b285bd TH |
1482 | } |
1483 | } | |
1484 | ||
838f13bf | 1485 | mutex_unlock(&blkcg_pol_mutex); |
8bd435b3 | 1486 | |
8bd435b3 | 1487 | /* everything is in place, add intf files for the new policy */ |
2ee867dc TH |
1488 | if (pol->dfl_cftypes) |
1489 | WARN_ON(cgroup_add_dfl_cftypes(&io_cgrp_subsys, | |
1490 | pol->dfl_cftypes)); | |
880f50e2 | 1491 | if (pol->legacy_cftypes) |
c165b3e3 | 1492 | WARN_ON(cgroup_add_legacy_cftypes(&io_cgrp_subsys, |
880f50e2 | 1493 | pol->legacy_cftypes)); |
838f13bf TH |
1494 | mutex_unlock(&blkcg_pol_register_mutex); |
1495 | return 0; | |
1496 | ||
06b285bd | 1497 | err_free_cpds: |
58a9edce | 1498 | if (pol->cpd_free_fn) { |
06b285bd | 1499 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
e4a9bde9 TH |
1500 | if (blkcg->cpd[pol->plid]) { |
1501 | pol->cpd_free_fn(blkcg->cpd[pol->plid]); | |
1502 | blkcg->cpd[pol->plid] = NULL; | |
1503 | } | |
06b285bd TH |
1504 | } |
1505 | } | |
1506 | blkcg_policy[pol->plid] = NULL; | |
838f13bf | 1507 | err_unlock: |
bc0d6501 | 1508 | mutex_unlock(&blkcg_pol_mutex); |
838f13bf | 1509 | mutex_unlock(&blkcg_pol_register_mutex); |
8bd435b3 | 1510 | return ret; |
3e252066 | 1511 | } |
3c798398 | 1512 | EXPORT_SYMBOL_GPL(blkcg_policy_register); |
3e252066 | 1513 | |
8bd435b3 | 1514 | /** |
3c798398 TH |
1515 | * blkcg_policy_unregister - unregister a blkcg policy |
1516 | * @pol: blkcg policy to unregister | |
8bd435b3 | 1517 | * |
3c798398 | 1518 | * Undo blkcg_policy_register(@pol). Might sleep. |
8bd435b3 | 1519 | */ |
3c798398 | 1520 | void blkcg_policy_unregister(struct blkcg_policy *pol) |
3e252066 | 1521 | { |
06b285bd TH |
1522 | struct blkcg *blkcg; |
1523 | ||
838f13bf | 1524 | mutex_lock(&blkcg_pol_register_mutex); |
bc0d6501 | 1525 | |
3c798398 | 1526 | if (WARN_ON(blkcg_policy[pol->plid] != pol)) |
8bd435b3 TH |
1527 | goto out_unlock; |
1528 | ||
1529 | /* kill the intf files first */ | |
2ee867dc TH |
1530 | if (pol->dfl_cftypes) |
1531 | cgroup_rm_cftypes(pol->dfl_cftypes); | |
880f50e2 TH |
1532 | if (pol->legacy_cftypes) |
1533 | cgroup_rm_cftypes(pol->legacy_cftypes); | |
44ea53de | 1534 | |
06b285bd | 1535 | /* remove cpds and unregister */ |
838f13bf | 1536 | mutex_lock(&blkcg_pol_mutex); |
06b285bd | 1537 | |
58a9edce | 1538 | if (pol->cpd_free_fn) { |
06b285bd | 1539 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
e4a9bde9 TH |
1540 | if (blkcg->cpd[pol->plid]) { |
1541 | pol->cpd_free_fn(blkcg->cpd[pol->plid]); | |
1542 | blkcg->cpd[pol->plid] = NULL; | |
1543 | } | |
06b285bd TH |
1544 | } |
1545 | } | |
3c798398 | 1546 | blkcg_policy[pol->plid] = NULL; |
06b285bd | 1547 | |
bc0d6501 | 1548 | mutex_unlock(&blkcg_pol_mutex); |
838f13bf TH |
1549 | out_unlock: |
1550 | mutex_unlock(&blkcg_pol_register_mutex); | |
3e252066 | 1551 | } |
3c798398 | 1552 | EXPORT_SYMBOL_GPL(blkcg_policy_unregister); |
903d23f0 | 1553 | |
d3f77dfd TH |
1554 | bool __blkcg_punt_bio_submit(struct bio *bio) |
1555 | { | |
1556 | struct blkcg_gq *blkg = bio->bi_blkg; | |
1557 | ||
1558 | /* consume the flag first */ | |
1559 | bio->bi_opf &= ~REQ_CGROUP_PUNT; | |
1560 | ||
1561 | /* never bounce for the root cgroup */ | |
1562 | if (!blkg->parent) | |
1563 | return false; | |
1564 | ||
1565 | spin_lock_bh(&blkg->async_bio_lock); | |
1566 | bio_list_add(&blkg->async_bios, bio); | |
1567 | spin_unlock_bh(&blkg->async_bio_lock); | |
1568 | ||
1569 | queue_work(blkcg_punt_bio_wq, &blkg->async_bio_work); | |
1570 | return true; | |
1571 | } | |
1572 | ||
d09d8df3 JB |
1573 | /* |
1574 | * Scale the accumulated delay based on how long it has been since we updated | |
1575 | * the delay. We only call this when we are adding delay, in case it's been a | |
1576 | * while since we added delay, and when we are checking to see if we need to | |
1577 | * delay a task, to account for any delays that may have occurred. | |
1578 | */ | |
1579 | static void blkcg_scale_delay(struct blkcg_gq *blkg, u64 now) | |
1580 | { | |
1581 | u64 old = atomic64_read(&blkg->delay_start); | |
1582 | ||
1583 | /* | |
1584 | * We only want to scale down every second. The idea here is that we | |
1585 | * want to delay people for min(delay_nsec, NSEC_PER_SEC) in a certain | |
1586 | * time window. We only want to throttle tasks for recent delay that | |
1587 | * has occurred, in 1 second time windows since that's the maximum | |
1588 | * things can be throttled. We save the current delay window in | |
1589 | * blkg->last_delay so we know what amount is still left to be charged | |
1590 | * to the blkg from this point onward. blkg->last_use keeps track of | |
1591 | * the use_delay counter. The idea is if we're unthrottling the blkg we | |
1592 | * are ok with whatever is happening now, and we can take away more of | |
1593 | * the accumulated delay as we've already throttled enough that | |
1594 | * everybody is happy with their IO latencies. | |
1595 | */ | |
1596 | if (time_before64(old + NSEC_PER_SEC, now) && | |
1597 | atomic64_cmpxchg(&blkg->delay_start, old, now) == old) { | |
1598 | u64 cur = atomic64_read(&blkg->delay_nsec); | |
1599 | u64 sub = min_t(u64, blkg->last_delay, now - old); | |
1600 | int cur_use = atomic_read(&blkg->use_delay); | |
1601 | ||
1602 | /* | |
1603 | * We've been unthrottled, subtract a larger chunk of our | |
1604 | * accumulated delay. | |
1605 | */ | |
1606 | if (cur_use < blkg->last_use) | |
1607 | sub = max_t(u64, sub, blkg->last_delay >> 1); | |
1608 | ||
1609 | /* | |
1610 | * This shouldn't happen, but handle it anyway. Our delay_nsec | |
1611 | * should only ever be growing except here where we subtract out | |
1612 | * min(last_delay, 1 second), but lord knows bugs happen and I'd | |
1613 | * rather not end up with negative numbers. | |
1614 | */ | |
1615 | if (unlikely(cur < sub)) { | |
1616 | atomic64_set(&blkg->delay_nsec, 0); | |
1617 | blkg->last_delay = 0; | |
1618 | } else { | |
1619 | atomic64_sub(sub, &blkg->delay_nsec); | |
1620 | blkg->last_delay = cur - sub; | |
1621 | } | |
1622 | blkg->last_use = cur_use; | |
1623 | } | |
1624 | } | |
1625 | ||
1626 | /* | |
1627 | * This is called when we want to actually walk up the hierarchy and check to | |
1628 | * see if we need to throttle, and then actually throttle if there is some | |
1629 | * accumulated delay. This should only be called upon return to user space so | |
1630 | * we're not holding some lock that would induce a priority inversion. | |
1631 | */ | |
1632 | static void blkcg_maybe_throttle_blkg(struct blkcg_gq *blkg, bool use_memdelay) | |
1633 | { | |
fd112c74 | 1634 | unsigned long pflags; |
d09d8df3 JB |
1635 | u64 now = ktime_to_ns(ktime_get()); |
1636 | u64 exp; | |
1637 | u64 delay_nsec = 0; | |
1638 | int tok; | |
1639 | ||
1640 | while (blkg->parent) { | |
1641 | if (atomic_read(&blkg->use_delay)) { | |
1642 | blkcg_scale_delay(blkg, now); | |
1643 | delay_nsec = max_t(u64, delay_nsec, | |
1644 | atomic64_read(&blkg->delay_nsec)); | |
1645 | } | |
1646 | blkg = blkg->parent; | |
1647 | } | |
1648 | ||
1649 | if (!delay_nsec) | |
1650 | return; | |
1651 | ||
1652 | /* | |
1653 | * Let's not sleep for all eternity if we've amassed a huge delay. | |
1654 | * Swapping or metadata IO can accumulate 10's of seconds worth of | |
1655 | * delay, and we want userspace to be able to do _something_ so cap the | |
1656 | * delays at 1 second. If there's 10's of seconds worth of delay then | |
1657 | * the tasks will be delayed for 1 second for every syscall. | |
1658 | */ | |
1659 | delay_nsec = min_t(u64, delay_nsec, 250 * NSEC_PER_MSEC); | |
1660 | ||
fd112c74 JB |
1661 | if (use_memdelay) |
1662 | psi_memstall_enter(&pflags); | |
d09d8df3 JB |
1663 | |
1664 | exp = ktime_add_ns(now, delay_nsec); | |
1665 | tok = io_schedule_prepare(); | |
1666 | do { | |
1667 | __set_current_state(TASK_KILLABLE); | |
1668 | if (!schedule_hrtimeout(&exp, HRTIMER_MODE_ABS)) | |
1669 | break; | |
1670 | } while (!fatal_signal_pending(current)); | |
1671 | io_schedule_finish(tok); | |
fd112c74 JB |
1672 | |
1673 | if (use_memdelay) | |
1674 | psi_memstall_leave(&pflags); | |
d09d8df3 JB |
1675 | } |
1676 | ||
1677 | /** | |
1678 | * blkcg_maybe_throttle_current - throttle the current task if it has been marked | |
1679 | * | |
1680 | * This is only called if we've been marked with set_notify_resume(). Obviously | |
1681 | * we can be set_notify_resume() for reasons other than blkcg throttling, so we | |
1682 | * check to see if current->throttle_queue is set and if not this doesn't do | |
1683 | * anything. This should only ever be called by the resume code, it's not meant | |
1684 | * to be called by people willy-nilly as it will actually do the work to | |
1685 | * throttle the task if it is setup for throttling. | |
1686 | */ | |
1687 | void blkcg_maybe_throttle_current(void) | |
1688 | { | |
1689 | struct request_queue *q = current->throttle_queue; | |
1690 | struct cgroup_subsys_state *css; | |
1691 | struct blkcg *blkcg; | |
1692 | struct blkcg_gq *blkg; | |
1693 | bool use_memdelay = current->use_memdelay; | |
1694 | ||
1695 | if (!q) | |
1696 | return; | |
1697 | ||
1698 | current->throttle_queue = NULL; | |
1699 | current->use_memdelay = false; | |
1700 | ||
1701 | rcu_read_lock(); | |
1702 | css = kthread_blkcg(); | |
1703 | if (css) | |
1704 | blkcg = css_to_blkcg(css); | |
1705 | else | |
1706 | blkcg = css_to_blkcg(task_css(current, io_cgrp_id)); | |
1707 | ||
1708 | if (!blkcg) | |
1709 | goto out; | |
1710 | blkg = blkg_lookup(blkcg, q); | |
1711 | if (!blkg) | |
1712 | goto out; | |
7754f669 | 1713 | if (!blkg_tryget(blkg)) |
d09d8df3 JB |
1714 | goto out; |
1715 | rcu_read_unlock(); | |
d09d8df3 JB |
1716 | |
1717 | blkcg_maybe_throttle_blkg(blkg, use_memdelay); | |
1718 | blkg_put(blkg); | |
cc7ecc25 | 1719 | blk_put_queue(q); |
d09d8df3 JB |
1720 | return; |
1721 | out: | |
1722 | rcu_read_unlock(); | |
1723 | blk_put_queue(q); | |
1724 | } | |
d09d8df3 JB |
1725 | |
1726 | /** | |
1727 | * blkcg_schedule_throttle - this task needs to check for throttling | |
537d71b3 BVA |
1728 | * @q: the request queue IO was submitted on |
1729 | * @use_memdelay: do we charge this to memory delay for PSI | |
d09d8df3 JB |
1730 | * |
1731 | * This is called by the IO controller when we know there's delay accumulated | |
1732 | * for the blkg for this task. We do not pass the blkg because there are places | |
1733 | * we call this that may not have that information, the swapping code for | |
1734 | * instance will only have a request_queue at that point. This set's the | |
1735 | * notify_resume for the task to check and see if it requires throttling before | |
1736 | * returning to user space. | |
1737 | * | |
1738 | * We will only schedule once per syscall. You can call this over and over | |
1739 | * again and it will only do the check once upon return to user space, and only | |
1740 | * throttle once. If the task needs to be throttled again it'll need to be | |
1741 | * re-set at the next time we see the task. | |
1742 | */ | |
1743 | void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay) | |
1744 | { | |
1745 | if (unlikely(current->flags & PF_KTHREAD)) | |
1746 | return; | |
1747 | ||
1748 | if (!blk_get_queue(q)) | |
1749 | return; | |
1750 | ||
1751 | if (current->throttle_queue) | |
1752 | blk_put_queue(current->throttle_queue); | |
1753 | current->throttle_queue = q; | |
1754 | if (use_memdelay) | |
1755 | current->use_memdelay = use_memdelay; | |
1756 | set_notify_resume(current); | |
1757 | } | |
d09d8df3 JB |
1758 | |
1759 | /** | |
1760 | * blkcg_add_delay - add delay to this blkg | |
537d71b3 BVA |
1761 | * @blkg: blkg of interest |
1762 | * @now: the current time in nanoseconds | |
1763 | * @delta: how many nanoseconds of delay to add | |
d09d8df3 JB |
1764 | * |
1765 | * Charge @delta to the blkg's current delay accumulation. This is used to | |
1766 | * throttle tasks if an IO controller thinks we need more throttling. | |
1767 | */ | |
1768 | void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta) | |
1769 | { | |
1770 | blkcg_scale_delay(blkg, now); | |
1771 | atomic64_add(delta, &blkg->delay_nsec); | |
1772 | } | |
d09d8df3 | 1773 | |
d3f77dfd TH |
1774 | static int __init blkcg_init(void) |
1775 | { | |
1776 | blkcg_punt_bio_wq = alloc_workqueue("blkcg_punt_bio", | |
1777 | WQ_MEM_RECLAIM | WQ_FREEZABLE | | |
1778 | WQ_UNBOUND | WQ_SYSFS, 0); | |
1779 | if (!blkcg_punt_bio_wq) | |
1780 | return -ENOMEM; | |
1781 | return 0; | |
1782 | } | |
1783 | subsys_initcall(blkcg_init); | |
1784 | ||
903d23f0 JB |
1785 | module_param(blkcg_debug_stats, bool, 0644); |
1786 | MODULE_PARM_DESC(blkcg_debug_stats, "True if you want debug stats, false if not"); |