Commit | Line | Data |
---|---|---|
31e4c28d VG |
1 | /* |
2 | * Common Block IO controller cgroup interface | |
3 | * | |
4 | * Based on ideas and code from CFQ, CFS and BFQ: | |
5 | * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> | |
6 | * | |
7 | * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> | |
8 | * Paolo Valente <paolo.valente@unimore.it> | |
9 | * | |
10 | * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com> | |
11 | * Nauman Rafique <nauman@google.com> | |
e48453c3 AA |
12 | * |
13 | * For policy-specific per-blkcg data: | |
14 | * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it> | |
15 | * Arianna Avanzini <avanzini.arianna@gmail.com> | |
31e4c28d VG |
16 | */ |
17 | #include <linux/ioprio.h> | |
22084190 | 18 | #include <linux/kdev_t.h> |
9d6a986c | 19 | #include <linux/module.h> |
174cd4b1 | 20 | #include <linux/sched/signal.h> |
accee785 | 21 | #include <linux/err.h> |
9195291e | 22 | #include <linux/blkdev.h> |
52ebea74 | 23 | #include <linux/backing-dev.h> |
5a0e3ad6 | 24 | #include <linux/slab.h> |
34d0f179 | 25 | #include <linux/genhd.h> |
72e06c25 | 26 | #include <linux/delay.h> |
9a9e8a26 | 27 | #include <linux/atomic.h> |
36aa9e5f | 28 | #include <linux/ctype.h> |
eea8f41c | 29 | #include <linux/blk-cgroup.h> |
d09d8df3 | 30 | #include <linux/tracehook.h> |
5efd6113 | 31 | #include "blk.h" |
3e252066 | 32 | |
84c124da DS |
33 | #define MAX_KEY_LEN 100 |
34 | ||
838f13bf TH |
35 | /* |
36 | * blkcg_pol_mutex protects blkcg_policy[] and policy [de]activation. | |
37 | * blkcg_pol_register_mutex nests outside of it and synchronizes entire | |
38 | * policy [un]register operations including cgroup file additions / | |
39 | * removals. Putting cgroup file registration outside blkcg_pol_mutex | |
40 | * allows grabbing it from cgroup callbacks. | |
41 | */ | |
42 | static DEFINE_MUTEX(blkcg_pol_register_mutex); | |
bc0d6501 | 43 | static DEFINE_MUTEX(blkcg_pol_mutex); |
923adde1 | 44 | |
e48453c3 | 45 | struct blkcg blkcg_root; |
3c798398 | 46 | EXPORT_SYMBOL_GPL(blkcg_root); |
9d6a986c | 47 | |
496d5e75 TH |
48 | struct cgroup_subsys_state * const blkcg_root_css = &blkcg_root.css; |
49 | ||
3c798398 | 50 | static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS]; |
035d10b2 | 51 | |
7876f930 TH |
52 | static LIST_HEAD(all_blkcgs); /* protected by blkcg_pol_mutex */ |
53 | ||
903d23f0 JB |
54 | static bool blkcg_debug_stats = false; |
55 | ||
a2b1693b | 56 | static bool blkcg_policy_enabled(struct request_queue *q, |
3c798398 | 57 | const struct blkcg_policy *pol) |
a2b1693b TH |
58 | { |
59 | return pol && test_bit(pol->plid, q->blkcg_pols); | |
60 | } | |
61 | ||
0381411e TH |
62 | /** |
63 | * blkg_free - free a blkg | |
64 | * @blkg: blkg to free | |
65 | * | |
66 | * Free @blkg which may be partially allocated. | |
67 | */ | |
3c798398 | 68 | static void blkg_free(struct blkcg_gq *blkg) |
0381411e | 69 | { |
e8989fae | 70 | int i; |
549d3aa8 TH |
71 | |
72 | if (!blkg) | |
73 | return; | |
74 | ||
db613670 | 75 | for (i = 0; i < BLKCG_MAX_POLS; i++) |
001bea73 TH |
76 | if (blkg->pd[i]) |
77 | blkcg_policy[i]->pd_free_fn(blkg->pd[i]); | |
e8989fae | 78 | |
994b7832 | 79 | if (blkg->blkcg != &blkcg_root) |
b425e504 | 80 | blk_exit_rl(blkg->q, &blkg->rl); |
77ea7338 TH |
81 | |
82 | blkg_rwstat_exit(&blkg->stat_ios); | |
83 | blkg_rwstat_exit(&blkg->stat_bytes); | |
549d3aa8 | 84 | kfree(blkg); |
0381411e TH |
85 | } |
86 | ||
87 | /** | |
88 | * blkg_alloc - allocate a blkg | |
89 | * @blkcg: block cgroup the new blkg is associated with | |
90 | * @q: request_queue the new blkg is associated with | |
15974993 | 91 | * @gfp_mask: allocation mask to use |
0381411e | 92 | * |
e8989fae | 93 | * Allocate a new blkg assocating @blkcg and @q. |
0381411e | 94 | */ |
15974993 TH |
95 | static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, |
96 | gfp_t gfp_mask) | |
0381411e | 97 | { |
3c798398 | 98 | struct blkcg_gq *blkg; |
e8989fae | 99 | int i; |
0381411e TH |
100 | |
101 | /* alloc and init base part */ | |
15974993 | 102 | blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node); |
0381411e TH |
103 | if (!blkg) |
104 | return NULL; | |
105 | ||
77ea7338 TH |
106 | if (blkg_rwstat_init(&blkg->stat_bytes, gfp_mask) || |
107 | blkg_rwstat_init(&blkg->stat_ios, gfp_mask)) | |
108 | goto err_free; | |
109 | ||
c875f4d0 | 110 | blkg->q = q; |
e8989fae | 111 | INIT_LIST_HEAD(&blkg->q_node); |
0381411e | 112 | blkg->blkcg = blkcg; |
a5049a8a | 113 | atomic_set(&blkg->refcnt, 1); |
0381411e | 114 | |
a051661c TH |
115 | /* root blkg uses @q->root_rl, init rl only for !root blkgs */ |
116 | if (blkcg != &blkcg_root) { | |
117 | if (blk_init_rl(&blkg->rl, q, gfp_mask)) | |
118 | goto err_free; | |
119 | blkg->rl.blkg = blkg; | |
120 | } | |
121 | ||
8bd435b3 | 122 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
3c798398 | 123 | struct blkcg_policy *pol = blkcg_policy[i]; |
e8989fae | 124 | struct blkg_policy_data *pd; |
0381411e | 125 | |
a2b1693b | 126 | if (!blkcg_policy_enabled(q, pol)) |
e8989fae TH |
127 | continue; |
128 | ||
129 | /* alloc per-policy data and attach it to blkg */ | |
001bea73 | 130 | pd = pol->pd_alloc_fn(gfp_mask, q->node); |
a051661c TH |
131 | if (!pd) |
132 | goto err_free; | |
549d3aa8 | 133 | |
e8989fae TH |
134 | blkg->pd[i] = pd; |
135 | pd->blkg = blkg; | |
b276a876 | 136 | pd->plid = i; |
e8989fae TH |
137 | } |
138 | ||
0381411e | 139 | return blkg; |
a051661c TH |
140 | |
141 | err_free: | |
142 | blkg_free(blkg); | |
143 | return NULL; | |
0381411e TH |
144 | } |
145 | ||
24f29046 TH |
146 | struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg, |
147 | struct request_queue *q, bool update_hint) | |
80fd9979 | 148 | { |
3c798398 | 149 | struct blkcg_gq *blkg; |
80fd9979 | 150 | |
a637120e | 151 | /* |
86cde6b6 TH |
152 | * Hint didn't match. Look up from the radix tree. Note that the |
153 | * hint can only be updated under queue_lock as otherwise @blkg | |
154 | * could have already been removed from blkg_tree. The caller is | |
155 | * responsible for grabbing queue_lock if @update_hint. | |
a637120e TH |
156 | */ |
157 | blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); | |
86cde6b6 TH |
158 | if (blkg && blkg->q == q) { |
159 | if (update_hint) { | |
160 | lockdep_assert_held(q->queue_lock); | |
161 | rcu_assign_pointer(blkcg->blkg_hint, blkg); | |
162 | } | |
a637120e | 163 | return blkg; |
86cde6b6 | 164 | } |
a637120e | 165 | |
80fd9979 TH |
166 | return NULL; |
167 | } | |
ae118896 | 168 | EXPORT_SYMBOL_GPL(blkg_lookup_slowpath); |
80fd9979 | 169 | |
15974993 | 170 | /* |
d708f0d5 JA |
171 | * If @new_blkg is %NULL, this function tries to allocate a new one as |
172 | * necessary using %GFP_NOWAIT. @new_blkg is always consumed on return. | |
15974993 | 173 | */ |
86cde6b6 | 174 | static struct blkcg_gq *blkg_create(struct blkcg *blkcg, |
d708f0d5 JA |
175 | struct request_queue *q, |
176 | struct blkcg_gq *new_blkg) | |
5624a4e4 | 177 | { |
d708f0d5 | 178 | struct blkcg_gq *blkg; |
ce7acfea | 179 | struct bdi_writeback_congested *wb_congested; |
f427d909 | 180 | int i, ret; |
5624a4e4 | 181 | |
cd1604fa TH |
182 | WARN_ON_ONCE(!rcu_read_lock_held()); |
183 | lockdep_assert_held(q->queue_lock); | |
184 | ||
7ee9c562 | 185 | /* blkg holds a reference to blkcg */ |
ec903c0c | 186 | if (!css_tryget_online(&blkcg->css)) { |
20386ce0 | 187 | ret = -ENODEV; |
93e6d5d8 | 188 | goto err_free_blkg; |
15974993 | 189 | } |
cd1604fa | 190 | |
dc3b17cc | 191 | wb_congested = wb_congested_get_create(q->backing_dev_info, |
d708f0d5 JA |
192 | blkcg->css.id, |
193 | GFP_NOWAIT | __GFP_NOWARN); | |
194 | if (!wb_congested) { | |
ce7acfea | 195 | ret = -ENOMEM; |
d708f0d5 | 196 | goto err_put_css; |
ce7acfea TH |
197 | } |
198 | ||
d708f0d5 JA |
199 | /* allocate */ |
200 | if (!new_blkg) { | |
201 | new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT | __GFP_NOWARN); | |
202 | if (unlikely(!new_blkg)) { | |
203 | ret = -ENOMEM; | |
204 | goto err_put_congested; | |
15974993 TH |
205 | } |
206 | } | |
d708f0d5 JA |
207 | blkg = new_blkg; |
208 | blkg->wb_congested = wb_congested; | |
cd1604fa | 209 | |
db613670 | 210 | /* link parent */ |
3c547865 TH |
211 | if (blkcg_parent(blkcg)) { |
212 | blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false); | |
213 | if (WARN_ON_ONCE(!blkg->parent)) { | |
20386ce0 | 214 | ret = -ENODEV; |
d708f0d5 | 215 | goto err_put_congested; |
3c547865 TH |
216 | } |
217 | blkg_get(blkg->parent); | |
218 | } | |
219 | ||
db613670 TH |
220 | /* invoke per-policy init */ |
221 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
222 | struct blkcg_policy *pol = blkcg_policy[i]; | |
223 | ||
224 | if (blkg->pd[i] && pol->pd_init_fn) | |
a9520cd6 | 225 | pol->pd_init_fn(blkg->pd[i]); |
db613670 TH |
226 | } |
227 | ||
228 | /* insert */ | |
cd1604fa | 229 | spin_lock(&blkcg->lock); |
a637120e TH |
230 | ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg); |
231 | if (likely(!ret)) { | |
232 | hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); | |
233 | list_add(&blkg->q_node, &q->blkg_list); | |
f427d909 TH |
234 | |
235 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
236 | struct blkcg_policy *pol = blkcg_policy[i]; | |
237 | ||
238 | if (blkg->pd[i] && pol->pd_online_fn) | |
a9520cd6 | 239 | pol->pd_online_fn(blkg->pd[i]); |
f427d909 | 240 | } |
a637120e | 241 | } |
f427d909 | 242 | blkg->online = true; |
cd1604fa | 243 | spin_unlock(&blkcg->lock); |
496fb780 | 244 | |
ec13b1d6 | 245 | if (!ret) |
a637120e | 246 | return blkg; |
15974993 | 247 | |
3c547865 TH |
248 | /* @blkg failed fully initialized, use the usual release path */ |
249 | blkg_put(blkg); | |
250 | return ERR_PTR(ret); | |
251 | ||
d708f0d5 JA |
252 | err_put_congested: |
253 | wb_congested_put(wb_congested); | |
254 | err_put_css: | |
496fb780 | 255 | css_put(&blkcg->css); |
93e6d5d8 | 256 | err_free_blkg: |
d708f0d5 | 257 | blkg_free(new_blkg); |
93e6d5d8 | 258 | return ERR_PTR(ret); |
31e4c28d | 259 | } |
3c96cb32 | 260 | |
86cde6b6 | 261 | /** |
d708f0d5 | 262 | * blkg_lookup_create - lookup blkg, try to create one if not there |
86cde6b6 TH |
263 | * @blkcg: blkcg of interest |
264 | * @q: request_queue of interest | |
265 | * | |
266 | * Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to | |
3c547865 TH |
267 | * create one. blkg creation is performed recursively from blkcg_root such |
268 | * that all non-root blkg's have access to the parent blkg. This function | |
269 | * should be called under RCU read lock and @q->queue_lock. | |
86cde6b6 TH |
270 | * |
271 | * Returns pointer to the looked up or created blkg on success, ERR_PTR() | |
272 | * value on error. If @q is dead, returns ERR_PTR(-EINVAL). If @q is not | |
273 | * dead and bypassing, returns ERR_PTR(-EBUSY). | |
274 | */ | |
d708f0d5 JA |
275 | struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, |
276 | struct request_queue *q) | |
3c96cb32 | 277 | { |
86cde6b6 TH |
278 | struct blkcg_gq *blkg; |
279 | ||
280 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
281 | lockdep_assert_held(q->queue_lock); | |
282 | ||
d708f0d5 JA |
283 | /* |
284 | * This could be the first entry point of blkcg implementation and | |
285 | * we shouldn't allow anything to go through for a bypassing queue. | |
286 | */ | |
287 | if (unlikely(blk_queue_bypass(q))) | |
288 | return ERR_PTR(blk_queue_dying(q) ? -ENODEV : -EBUSY); | |
289 | ||
86cde6b6 TH |
290 | blkg = __blkg_lookup(blkcg, q, true); |
291 | if (blkg) | |
292 | return blkg; | |
293 | ||
3c547865 TH |
294 | /* |
295 | * Create blkgs walking down from blkcg_root to @blkcg, so that all | |
296 | * non-root blkgs have access to their parents. | |
297 | */ | |
298 | while (true) { | |
299 | struct blkcg *pos = blkcg; | |
300 | struct blkcg *parent = blkcg_parent(blkcg); | |
301 | ||
302 | while (parent && !__blkg_lookup(parent, q, false)) { | |
303 | pos = parent; | |
304 | parent = blkcg_parent(parent); | |
305 | } | |
306 | ||
d708f0d5 | 307 | blkg = blkg_create(pos, q, NULL); |
3c547865 TH |
308 | if (pos == blkcg || IS_ERR(blkg)) |
309 | return blkg; | |
310 | } | |
3c96cb32 | 311 | } |
31e4c28d | 312 | |
3c798398 | 313 | static void blkg_destroy(struct blkcg_gq *blkg) |
03aa264a | 314 | { |
3c798398 | 315 | struct blkcg *blkcg = blkg->blkcg; |
77ea7338 | 316 | struct blkcg_gq *parent = blkg->parent; |
6b065462 | 317 | int i; |
03aa264a | 318 | |
27e1f9d1 | 319 | lockdep_assert_held(blkg->q->queue_lock); |
9f13ef67 | 320 | lockdep_assert_held(&blkcg->lock); |
03aa264a TH |
321 | |
322 | /* Something wrong if we are trying to remove same group twice */ | |
e8989fae | 323 | WARN_ON_ONCE(list_empty(&blkg->q_node)); |
9f13ef67 | 324 | WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node)); |
a637120e | 325 | |
6b065462 DZF |
326 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
327 | struct blkcg_policy *pol = blkcg_policy[i]; | |
328 | ||
329 | if (blkg->pd[i] && pol->pd_offline_fn) | |
330 | pol->pd_offline_fn(blkg->pd[i]); | |
331 | } | |
332 | ||
77ea7338 TH |
333 | if (parent) { |
334 | blkg_rwstat_add_aux(&parent->stat_bytes, &blkg->stat_bytes); | |
335 | blkg_rwstat_add_aux(&parent->stat_ios, &blkg->stat_ios); | |
336 | } | |
337 | ||
f427d909 TH |
338 | blkg->online = false; |
339 | ||
a637120e | 340 | radix_tree_delete(&blkcg->blkg_tree, blkg->q->id); |
e8989fae | 341 | list_del_init(&blkg->q_node); |
9f13ef67 | 342 | hlist_del_init_rcu(&blkg->blkcg_node); |
03aa264a | 343 | |
a637120e TH |
344 | /* |
345 | * Both setting lookup hint to and clearing it from @blkg are done | |
346 | * under queue_lock. If it's not pointing to @blkg now, it never | |
347 | * will. Hint assignment itself can race safely. | |
348 | */ | |
ec6c676a | 349 | if (rcu_access_pointer(blkcg->blkg_hint) == blkg) |
a637120e TH |
350 | rcu_assign_pointer(blkcg->blkg_hint, NULL); |
351 | ||
03aa264a TH |
352 | /* |
353 | * Put the reference taken at the time of creation so that when all | |
354 | * queues are gone, group can be destroyed. | |
355 | */ | |
356 | blkg_put(blkg); | |
357 | } | |
358 | ||
9f13ef67 TH |
359 | /** |
360 | * blkg_destroy_all - destroy all blkgs associated with a request_queue | |
361 | * @q: request_queue of interest | |
9f13ef67 | 362 | * |
3c96cb32 | 363 | * Destroy all blkgs associated with @q. |
9f13ef67 | 364 | */ |
3c96cb32 | 365 | static void blkg_destroy_all(struct request_queue *q) |
72e06c25 | 366 | { |
3c798398 | 367 | struct blkcg_gq *blkg, *n; |
72e06c25 | 368 | |
6d18b008 | 369 | lockdep_assert_held(q->queue_lock); |
72e06c25 | 370 | |
9f13ef67 | 371 | list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { |
3c798398 | 372 | struct blkcg *blkcg = blkg->blkcg; |
72e06c25 | 373 | |
9f13ef67 TH |
374 | spin_lock(&blkcg->lock); |
375 | blkg_destroy(blkg); | |
376 | spin_unlock(&blkcg->lock); | |
72e06c25 | 377 | } |
6fe810bd TH |
378 | |
379 | q->root_blkg = NULL; | |
380 | q->root_rl.blkg = NULL; | |
72e06c25 TH |
381 | } |
382 | ||
2a4fd070 TH |
383 | /* |
384 | * A group is RCU protected, but having an rcu lock does not mean that one | |
385 | * can access all the fields of blkg and assume these are valid. For | |
386 | * example, don't try to follow throtl_data and request queue links. | |
387 | * | |
388 | * Having a reference to blkg under an rcu allows accesses to only values | |
389 | * local to groups like group stats and group rate limits. | |
390 | */ | |
391 | void __blkg_release_rcu(struct rcu_head *rcu_head) | |
1adaf3dd | 392 | { |
2a4fd070 | 393 | struct blkcg_gq *blkg = container_of(rcu_head, struct blkcg_gq, rcu_head); |
db613670 | 394 | |
3c547865 | 395 | /* release the blkcg and parent blkg refs this blkg has been holding */ |
1adaf3dd | 396 | css_put(&blkg->blkcg->css); |
a5049a8a | 397 | if (blkg->parent) |
3c547865 | 398 | blkg_put(blkg->parent); |
1adaf3dd | 399 | |
ce7acfea TH |
400 | wb_congested_put(blkg->wb_congested); |
401 | ||
2a4fd070 | 402 | blkg_free(blkg); |
1adaf3dd | 403 | } |
2a4fd070 | 404 | EXPORT_SYMBOL_GPL(__blkg_release_rcu); |
1adaf3dd | 405 | |
a051661c TH |
406 | /* |
407 | * The next function used by blk_queue_for_each_rl(). It's a bit tricky | |
408 | * because the root blkg uses @q->root_rl instead of its own rl. | |
409 | */ | |
410 | struct request_list *__blk_queue_next_rl(struct request_list *rl, | |
411 | struct request_queue *q) | |
412 | { | |
413 | struct list_head *ent; | |
414 | struct blkcg_gq *blkg; | |
415 | ||
416 | /* | |
417 | * Determine the current blkg list_head. The first entry is | |
418 | * root_rl which is off @q->blkg_list and mapped to the head. | |
419 | */ | |
420 | if (rl == &q->root_rl) { | |
421 | ent = &q->blkg_list; | |
65c77fd9 JN |
422 | /* There are no more block groups, hence no request lists */ |
423 | if (list_empty(ent)) | |
424 | return NULL; | |
a051661c TH |
425 | } else { |
426 | blkg = container_of(rl, struct blkcg_gq, rl); | |
427 | ent = &blkg->q_node; | |
428 | } | |
429 | ||
430 | /* walk to the next list_head, skip root blkcg */ | |
431 | ent = ent->next; | |
432 | if (ent == &q->root_blkg->q_node) | |
433 | ent = ent->next; | |
434 | if (ent == &q->blkg_list) | |
435 | return NULL; | |
436 | ||
437 | blkg = container_of(ent, struct blkcg_gq, q_node); | |
438 | return &blkg->rl; | |
439 | } | |
440 | ||
182446d0 TH |
441 | static int blkcg_reset_stats(struct cgroup_subsys_state *css, |
442 | struct cftype *cftype, u64 val) | |
303a3acb | 443 | { |
182446d0 | 444 | struct blkcg *blkcg = css_to_blkcg(css); |
3c798398 | 445 | struct blkcg_gq *blkg; |
bc0d6501 | 446 | int i; |
303a3acb | 447 | |
838f13bf | 448 | mutex_lock(&blkcg_pol_mutex); |
303a3acb | 449 | spin_lock_irq(&blkcg->lock); |
997a026c TH |
450 | |
451 | /* | |
452 | * Note that stat reset is racy - it doesn't synchronize against | |
453 | * stat updates. This is a debug feature which shouldn't exist | |
454 | * anyway. If you get hit by a race, retry. | |
455 | */ | |
b67bfe0d | 456 | hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { |
77ea7338 TH |
457 | blkg_rwstat_reset(&blkg->stat_bytes); |
458 | blkg_rwstat_reset(&blkg->stat_ios); | |
459 | ||
8bd435b3 | 460 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
3c798398 | 461 | struct blkcg_policy *pol = blkcg_policy[i]; |
549d3aa8 | 462 | |
a9520cd6 TH |
463 | if (blkg->pd[i] && pol->pd_reset_stats_fn) |
464 | pol->pd_reset_stats_fn(blkg->pd[i]); | |
bc0d6501 | 465 | } |
303a3acb | 466 | } |
f0bdc8cd | 467 | |
303a3acb | 468 | spin_unlock_irq(&blkcg->lock); |
bc0d6501 | 469 | mutex_unlock(&blkcg_pol_mutex); |
303a3acb DS |
470 | return 0; |
471 | } | |
472 | ||
dd165eb3 | 473 | const char *blkg_dev_name(struct blkcg_gq *blkg) |
303a3acb | 474 | { |
d3d32e69 | 475 | /* some drivers (floppy) instantiate a queue w/o disk registered */ |
dc3b17cc JK |
476 | if (blkg->q->backing_dev_info->dev) |
477 | return dev_name(blkg->q->backing_dev_info->dev); | |
d3d32e69 | 478 | return NULL; |
303a3acb | 479 | } |
dd165eb3 | 480 | EXPORT_SYMBOL_GPL(blkg_dev_name); |
303a3acb | 481 | |
d3d32e69 TH |
482 | /** |
483 | * blkcg_print_blkgs - helper for printing per-blkg data | |
484 | * @sf: seq_file to print to | |
485 | * @blkcg: blkcg of interest | |
486 | * @prfill: fill function to print out a blkg | |
487 | * @pol: policy in question | |
488 | * @data: data to be passed to @prfill | |
489 | * @show_total: to print out sum of prfill return values or not | |
490 | * | |
491 | * This function invokes @prfill on each blkg of @blkcg if pd for the | |
492 | * policy specified by @pol exists. @prfill is invoked with @sf, the | |
810ecfa7 TH |
493 | * policy data and @data and the matching queue lock held. If @show_total |
494 | * is %true, the sum of the return values from @prfill is printed with | |
495 | * "Total" label at the end. | |
d3d32e69 TH |
496 | * |
497 | * This is to be used to construct print functions for | |
498 | * cftype->read_seq_string method. | |
499 | */ | |
3c798398 | 500 | void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg, |
f95a04af TH |
501 | u64 (*prfill)(struct seq_file *, |
502 | struct blkg_policy_data *, int), | |
3c798398 | 503 | const struct blkcg_policy *pol, int data, |
ec399347 | 504 | bool show_total) |
5624a4e4 | 505 | { |
3c798398 | 506 | struct blkcg_gq *blkg; |
d3d32e69 | 507 | u64 total = 0; |
5624a4e4 | 508 | |
810ecfa7 | 509 | rcu_read_lock(); |
ee89f812 | 510 | hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { |
810ecfa7 | 511 | spin_lock_irq(blkg->q->queue_lock); |
a2b1693b | 512 | if (blkcg_policy_enabled(blkg->q, pol)) |
f95a04af | 513 | total += prfill(sf, blkg->pd[pol->plid], data); |
810ecfa7 TH |
514 | spin_unlock_irq(blkg->q->queue_lock); |
515 | } | |
516 | rcu_read_unlock(); | |
d3d32e69 TH |
517 | |
518 | if (show_total) | |
519 | seq_printf(sf, "Total %llu\n", (unsigned long long)total); | |
520 | } | |
829fdb50 | 521 | EXPORT_SYMBOL_GPL(blkcg_print_blkgs); |
d3d32e69 TH |
522 | |
523 | /** | |
524 | * __blkg_prfill_u64 - prfill helper for a single u64 value | |
525 | * @sf: seq_file to print to | |
f95a04af | 526 | * @pd: policy private data of interest |
d3d32e69 TH |
527 | * @v: value to print |
528 | * | |
f95a04af | 529 | * Print @v to @sf for the device assocaited with @pd. |
d3d32e69 | 530 | */ |
f95a04af | 531 | u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v) |
d3d32e69 | 532 | { |
f95a04af | 533 | const char *dname = blkg_dev_name(pd->blkg); |
d3d32e69 TH |
534 | |
535 | if (!dname) | |
536 | return 0; | |
537 | ||
538 | seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v); | |
539 | return v; | |
540 | } | |
829fdb50 | 541 | EXPORT_SYMBOL_GPL(__blkg_prfill_u64); |
d3d32e69 TH |
542 | |
543 | /** | |
544 | * __blkg_prfill_rwstat - prfill helper for a blkg_rwstat | |
545 | * @sf: seq_file to print to | |
f95a04af | 546 | * @pd: policy private data of interest |
d3d32e69 TH |
547 | * @rwstat: rwstat to print |
548 | * | |
f95a04af | 549 | * Print @rwstat to @sf for the device assocaited with @pd. |
d3d32e69 | 550 | */ |
f95a04af | 551 | u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, |
829fdb50 | 552 | const struct blkg_rwstat *rwstat) |
d3d32e69 TH |
553 | { |
554 | static const char *rwstr[] = { | |
555 | [BLKG_RWSTAT_READ] = "Read", | |
556 | [BLKG_RWSTAT_WRITE] = "Write", | |
557 | [BLKG_RWSTAT_SYNC] = "Sync", | |
558 | [BLKG_RWSTAT_ASYNC] = "Async", | |
636620b6 | 559 | [BLKG_RWSTAT_DISCARD] = "Discard", |
d3d32e69 | 560 | }; |
f95a04af | 561 | const char *dname = blkg_dev_name(pd->blkg); |
d3d32e69 TH |
562 | u64 v; |
563 | int i; | |
564 | ||
565 | if (!dname) | |
566 | return 0; | |
567 | ||
568 | for (i = 0; i < BLKG_RWSTAT_NR; i++) | |
569 | seq_printf(sf, "%s %s %llu\n", dname, rwstr[i], | |
24bdb8ef | 570 | (unsigned long long)atomic64_read(&rwstat->aux_cnt[i])); |
d3d32e69 | 571 | |
24bdb8ef | 572 | v = atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_READ]) + |
636620b6 TH |
573 | atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_WRITE]) + |
574 | atomic64_read(&rwstat->aux_cnt[BLKG_RWSTAT_DISCARD]); | |
d3d32e69 TH |
575 | seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v); |
576 | return v; | |
577 | } | |
b50da39f | 578 | EXPORT_SYMBOL_GPL(__blkg_prfill_rwstat); |
d3d32e69 | 579 | |
5bc4afb1 TH |
580 | /** |
581 | * blkg_prfill_stat - prfill callback for blkg_stat | |
582 | * @sf: seq_file to print to | |
f95a04af TH |
583 | * @pd: policy private data of interest |
584 | * @off: offset to the blkg_stat in @pd | |
5bc4afb1 TH |
585 | * |
586 | * prfill callback for printing a blkg_stat. | |
587 | */ | |
f95a04af | 588 | u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off) |
d3d32e69 | 589 | { |
f95a04af | 590 | return __blkg_prfill_u64(sf, pd, blkg_stat_read((void *)pd + off)); |
d3d32e69 | 591 | } |
5bc4afb1 | 592 | EXPORT_SYMBOL_GPL(blkg_prfill_stat); |
d3d32e69 | 593 | |
5bc4afb1 TH |
594 | /** |
595 | * blkg_prfill_rwstat - prfill callback for blkg_rwstat | |
596 | * @sf: seq_file to print to | |
f95a04af TH |
597 | * @pd: policy private data of interest |
598 | * @off: offset to the blkg_rwstat in @pd | |
5bc4afb1 TH |
599 | * |
600 | * prfill callback for printing a blkg_rwstat. | |
601 | */ | |
f95a04af TH |
602 | u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, |
603 | int off) | |
d3d32e69 | 604 | { |
f95a04af | 605 | struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd + off); |
d3d32e69 | 606 | |
f95a04af | 607 | return __blkg_prfill_rwstat(sf, pd, &rwstat); |
d3d32e69 | 608 | } |
5bc4afb1 | 609 | EXPORT_SYMBOL_GPL(blkg_prfill_rwstat); |
d3d32e69 | 610 | |
77ea7338 TH |
611 | static u64 blkg_prfill_rwstat_field(struct seq_file *sf, |
612 | struct blkg_policy_data *pd, int off) | |
613 | { | |
614 | struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd->blkg + off); | |
615 | ||
616 | return __blkg_prfill_rwstat(sf, pd, &rwstat); | |
617 | } | |
618 | ||
619 | /** | |
620 | * blkg_print_stat_bytes - seq_show callback for blkg->stat_bytes | |
621 | * @sf: seq_file to print to | |
622 | * @v: unused | |
623 | * | |
624 | * To be used as cftype->seq_show to print blkg->stat_bytes. | |
625 | * cftype->private must be set to the blkcg_policy. | |
626 | */ | |
627 | int blkg_print_stat_bytes(struct seq_file *sf, void *v) | |
628 | { | |
629 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), | |
630 | blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private, | |
631 | offsetof(struct blkcg_gq, stat_bytes), true); | |
632 | return 0; | |
633 | } | |
634 | EXPORT_SYMBOL_GPL(blkg_print_stat_bytes); | |
635 | ||
636 | /** | |
637 | * blkg_print_stat_bytes - seq_show callback for blkg->stat_ios | |
638 | * @sf: seq_file to print to | |
639 | * @v: unused | |
640 | * | |
641 | * To be used as cftype->seq_show to print blkg->stat_ios. cftype->private | |
642 | * must be set to the blkcg_policy. | |
643 | */ | |
644 | int blkg_print_stat_ios(struct seq_file *sf, void *v) | |
645 | { | |
646 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), | |
647 | blkg_prfill_rwstat_field, (void *)seq_cft(sf)->private, | |
648 | offsetof(struct blkcg_gq, stat_ios), true); | |
649 | return 0; | |
650 | } | |
651 | EXPORT_SYMBOL_GPL(blkg_print_stat_ios); | |
652 | ||
653 | static u64 blkg_prfill_rwstat_field_recursive(struct seq_file *sf, | |
654 | struct blkg_policy_data *pd, | |
655 | int off) | |
656 | { | |
657 | struct blkg_rwstat rwstat = blkg_rwstat_recursive_sum(pd->blkg, | |
658 | NULL, off); | |
659 | return __blkg_prfill_rwstat(sf, pd, &rwstat); | |
660 | } | |
661 | ||
662 | /** | |
663 | * blkg_print_stat_bytes_recursive - recursive version of blkg_print_stat_bytes | |
664 | * @sf: seq_file to print to | |
665 | * @v: unused | |
666 | */ | |
667 | int blkg_print_stat_bytes_recursive(struct seq_file *sf, void *v) | |
668 | { | |
669 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), | |
670 | blkg_prfill_rwstat_field_recursive, | |
671 | (void *)seq_cft(sf)->private, | |
672 | offsetof(struct blkcg_gq, stat_bytes), true); | |
673 | return 0; | |
674 | } | |
675 | EXPORT_SYMBOL_GPL(blkg_print_stat_bytes_recursive); | |
676 | ||
677 | /** | |
678 | * blkg_print_stat_ios_recursive - recursive version of blkg_print_stat_ios | |
679 | * @sf: seq_file to print to | |
680 | * @v: unused | |
681 | */ | |
682 | int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v) | |
683 | { | |
684 | blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), | |
685 | blkg_prfill_rwstat_field_recursive, | |
686 | (void *)seq_cft(sf)->private, | |
687 | offsetof(struct blkcg_gq, stat_ios), true); | |
688 | return 0; | |
689 | } | |
690 | EXPORT_SYMBOL_GPL(blkg_print_stat_ios_recursive); | |
691 | ||
16b3de66 TH |
692 | /** |
693 | * blkg_stat_recursive_sum - collect hierarchical blkg_stat | |
f12c74ca TH |
694 | * @blkg: blkg of interest |
695 | * @pol: blkcg_policy which contains the blkg_stat | |
696 | * @off: offset to the blkg_stat in blkg_policy_data or @blkg | |
16b3de66 | 697 | * |
f12c74ca TH |
698 | * Collect the blkg_stat specified by @blkg, @pol and @off and all its |
699 | * online descendants and their aux counts. The caller must be holding the | |
700 | * queue lock for online tests. | |
701 | * | |
702 | * If @pol is NULL, blkg_stat is at @off bytes into @blkg; otherwise, it is | |
703 | * at @off bytes into @blkg's blkg_policy_data of the policy. | |
16b3de66 | 704 | */ |
f12c74ca TH |
705 | u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg, |
706 | struct blkcg_policy *pol, int off) | |
16b3de66 | 707 | { |
16b3de66 | 708 | struct blkcg_gq *pos_blkg; |
492eb21b | 709 | struct cgroup_subsys_state *pos_css; |
bd8815a6 | 710 | u64 sum = 0; |
16b3de66 | 711 | |
f12c74ca | 712 | lockdep_assert_held(blkg->q->queue_lock); |
16b3de66 | 713 | |
16b3de66 | 714 | rcu_read_lock(); |
f12c74ca TH |
715 | blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) { |
716 | struct blkg_stat *stat; | |
717 | ||
718 | if (!pos_blkg->online) | |
719 | continue; | |
16b3de66 | 720 | |
f12c74ca TH |
721 | if (pol) |
722 | stat = (void *)blkg_to_pd(pos_blkg, pol) + off; | |
723 | else | |
724 | stat = (void *)blkg + off; | |
725 | ||
726 | sum += blkg_stat_read(stat) + atomic64_read(&stat->aux_cnt); | |
16b3de66 TH |
727 | } |
728 | rcu_read_unlock(); | |
729 | ||
730 | return sum; | |
731 | } | |
732 | EXPORT_SYMBOL_GPL(blkg_stat_recursive_sum); | |
733 | ||
734 | /** | |
735 | * blkg_rwstat_recursive_sum - collect hierarchical blkg_rwstat | |
f12c74ca TH |
736 | * @blkg: blkg of interest |
737 | * @pol: blkcg_policy which contains the blkg_rwstat | |
738 | * @off: offset to the blkg_rwstat in blkg_policy_data or @blkg | |
16b3de66 | 739 | * |
f12c74ca TH |
740 | * Collect the blkg_rwstat specified by @blkg, @pol and @off and all its |
741 | * online descendants and their aux counts. The caller must be holding the | |
742 | * queue lock for online tests. | |
743 | * | |
744 | * If @pol is NULL, blkg_rwstat is at @off bytes into @blkg; otherwise, it | |
745 | * is at @off bytes into @blkg's blkg_policy_data of the policy. | |
16b3de66 | 746 | */ |
f12c74ca TH |
747 | struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, |
748 | struct blkcg_policy *pol, int off) | |
16b3de66 | 749 | { |
16b3de66 | 750 | struct blkcg_gq *pos_blkg; |
492eb21b | 751 | struct cgroup_subsys_state *pos_css; |
bd8815a6 | 752 | struct blkg_rwstat sum = { }; |
16b3de66 TH |
753 | int i; |
754 | ||
f12c74ca | 755 | lockdep_assert_held(blkg->q->queue_lock); |
16b3de66 | 756 | |
16b3de66 | 757 | rcu_read_lock(); |
f12c74ca | 758 | blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) { |
3a7faead | 759 | struct blkg_rwstat *rwstat; |
16b3de66 TH |
760 | |
761 | if (!pos_blkg->online) | |
762 | continue; | |
763 | ||
f12c74ca TH |
764 | if (pol) |
765 | rwstat = (void *)blkg_to_pd(pos_blkg, pol) + off; | |
766 | else | |
767 | rwstat = (void *)pos_blkg + off; | |
768 | ||
16b3de66 | 769 | for (i = 0; i < BLKG_RWSTAT_NR; i++) |
3a7faead TH |
770 | atomic64_add(atomic64_read(&rwstat->aux_cnt[i]) + |
771 | percpu_counter_sum_positive(&rwstat->cpu_cnt[i]), | |
772 | &sum.aux_cnt[i]); | |
16b3de66 TH |
773 | } |
774 | rcu_read_unlock(); | |
775 | ||
776 | return sum; | |
777 | } | |
778 | EXPORT_SYMBOL_GPL(blkg_rwstat_recursive_sum); | |
779 | ||
457e490f TE |
780 | /* Performs queue bypass and policy enabled checks then looks up blkg. */ |
781 | static struct blkcg_gq *blkg_lookup_check(struct blkcg *blkcg, | |
782 | const struct blkcg_policy *pol, | |
783 | struct request_queue *q) | |
784 | { | |
785 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
786 | lockdep_assert_held(q->queue_lock); | |
787 | ||
788 | if (!blkcg_policy_enabled(q, pol)) | |
789 | return ERR_PTR(-EOPNOTSUPP); | |
790 | ||
791 | /* | |
792 | * This could be the first entry point of blkcg implementation and | |
793 | * we shouldn't allow anything to go through for a bypassing queue. | |
794 | */ | |
795 | if (unlikely(blk_queue_bypass(q))) | |
796 | return ERR_PTR(blk_queue_dying(q) ? -ENODEV : -EBUSY); | |
797 | ||
798 | return __blkg_lookup(blkcg, q, true /* update_hint */); | |
799 | } | |
800 | ||
3a8b31d3 TH |
801 | /** |
802 | * blkg_conf_prep - parse and prepare for per-blkg config update | |
803 | * @blkcg: target block cgroup | |
da8b0662 | 804 | * @pol: target policy |
3a8b31d3 TH |
805 | * @input: input string |
806 | * @ctx: blkg_conf_ctx to be filled | |
807 | * | |
808 | * Parse per-blkg config update from @input and initialize @ctx with the | |
36aa9e5f TH |
809 | * result. @ctx->blkg points to the blkg to be updated and @ctx->body the |
810 | * part of @input following MAJ:MIN. This function returns with RCU read | |
811 | * lock and queue lock held and must be paired with blkg_conf_finish(). | |
3a8b31d3 | 812 | */ |
3c798398 | 813 | int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, |
36aa9e5f | 814 | char *input, struct blkg_conf_ctx *ctx) |
da8b0662 | 815 | __acquires(rcu) __acquires(disk->queue->queue_lock) |
34d0f179 | 816 | { |
3a8b31d3 | 817 | struct gendisk *disk; |
457e490f | 818 | struct request_queue *q; |
3c798398 | 819 | struct blkcg_gq *blkg; |
726fa694 | 820 | unsigned int major, minor; |
36aa9e5f TH |
821 | int key_len, part, ret; |
822 | char *body; | |
34d0f179 | 823 | |
36aa9e5f | 824 | if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2) |
726fa694 | 825 | return -EINVAL; |
3a8b31d3 | 826 | |
36aa9e5f TH |
827 | body = input + key_len; |
828 | if (!isspace(*body)) | |
829 | return -EINVAL; | |
830 | body = skip_spaces(body); | |
831 | ||
726fa694 | 832 | disk = get_gendisk(MKDEV(major, minor), &part); |
5f6c2d2b | 833 | if (!disk) |
20386ce0 | 834 | return -ENODEV; |
5f6c2d2b | 835 | if (part) { |
457e490f TE |
836 | ret = -ENODEV; |
837 | goto fail; | |
5f6c2d2b | 838 | } |
e56da7e2 | 839 | |
457e490f | 840 | q = disk->queue; |
da8b0662 | 841 | |
457e490f TE |
842 | rcu_read_lock(); |
843 | spin_lock_irq(q->queue_lock); | |
e56da7e2 | 844 | |
457e490f | 845 | blkg = blkg_lookup_check(blkcg, pol, q); |
4bfd482e TH |
846 | if (IS_ERR(blkg)) { |
847 | ret = PTR_ERR(blkg); | |
457e490f TE |
848 | goto fail_unlock; |
849 | } | |
850 | ||
851 | if (blkg) | |
852 | goto success; | |
853 | ||
854 | /* | |
855 | * Create blkgs walking down from blkcg_root to @blkcg, so that all | |
856 | * non-root blkgs have access to their parents. | |
857 | */ | |
858 | while (true) { | |
859 | struct blkcg *pos = blkcg; | |
860 | struct blkcg *parent; | |
861 | struct blkcg_gq *new_blkg; | |
862 | ||
863 | parent = blkcg_parent(blkcg); | |
864 | while (parent && !__blkg_lookup(parent, q, false)) { | |
865 | pos = parent; | |
866 | parent = blkcg_parent(parent); | |
867 | } | |
868 | ||
869 | /* Drop locks to do new blkg allocation with GFP_KERNEL. */ | |
870 | spin_unlock_irq(q->queue_lock); | |
3a8b31d3 | 871 | rcu_read_unlock(); |
457e490f TE |
872 | |
873 | new_blkg = blkg_alloc(pos, q, GFP_KERNEL); | |
874 | if (unlikely(!new_blkg)) { | |
875 | ret = -ENOMEM; | |
876 | goto fail; | |
7702e8f4 | 877 | } |
3a8b31d3 | 878 | |
457e490f TE |
879 | rcu_read_lock(); |
880 | spin_lock_irq(q->queue_lock); | |
881 | ||
882 | blkg = blkg_lookup_check(pos, pol, q); | |
883 | if (IS_ERR(blkg)) { | |
884 | ret = PTR_ERR(blkg); | |
885 | goto fail_unlock; | |
886 | } | |
887 | ||
888 | if (blkg) { | |
889 | blkg_free(new_blkg); | |
890 | } else { | |
891 | blkg = blkg_create(pos, q, new_blkg); | |
892 | if (unlikely(IS_ERR(blkg))) { | |
893 | ret = PTR_ERR(blkg); | |
894 | goto fail_unlock; | |
895 | } | |
896 | } | |
897 | ||
898 | if (pos == blkcg) | |
899 | goto success; | |
900 | } | |
901 | success: | |
3a8b31d3 TH |
902 | ctx->disk = disk; |
903 | ctx->blkg = blkg; | |
36aa9e5f | 904 | ctx->body = body; |
726fa694 | 905 | return 0; |
457e490f TE |
906 | |
907 | fail_unlock: | |
908 | spin_unlock_irq(q->queue_lock); | |
909 | rcu_read_unlock(); | |
910 | fail: | |
9df6c299 | 911 | put_disk_and_module(disk); |
457e490f TE |
912 | /* |
913 | * If queue was bypassing, we should retry. Do so after a | |
914 | * short msleep(). It isn't strictly necessary but queue | |
915 | * can be bypassing for some time and it's always nice to | |
916 | * avoid busy looping. | |
917 | */ | |
918 | if (ret == -EBUSY) { | |
919 | msleep(10); | |
920 | ret = restart_syscall(); | |
921 | } | |
922 | return ret; | |
34d0f179 | 923 | } |
829fdb50 | 924 | EXPORT_SYMBOL_GPL(blkg_conf_prep); |
34d0f179 | 925 | |
3a8b31d3 TH |
926 | /** |
927 | * blkg_conf_finish - finish up per-blkg config update | |
928 | * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep() | |
929 | * | |
930 | * Finish up after per-blkg config update. This function must be paired | |
931 | * with blkg_conf_prep(). | |
932 | */ | |
829fdb50 | 933 | void blkg_conf_finish(struct blkg_conf_ctx *ctx) |
da8b0662 | 934 | __releases(ctx->disk->queue->queue_lock) __releases(rcu) |
34d0f179 | 935 | { |
da8b0662 | 936 | spin_unlock_irq(ctx->disk->queue->queue_lock); |
3a8b31d3 | 937 | rcu_read_unlock(); |
9df6c299 | 938 | put_disk_and_module(ctx->disk); |
34d0f179 | 939 | } |
829fdb50 | 940 | EXPORT_SYMBOL_GPL(blkg_conf_finish); |
34d0f179 | 941 | |
2ee867dc TH |
942 | static int blkcg_print_stat(struct seq_file *sf, void *v) |
943 | { | |
944 | struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); | |
945 | struct blkcg_gq *blkg; | |
946 | ||
947 | rcu_read_lock(); | |
948 | ||
949 | hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { | |
950 | const char *dname; | |
903d23f0 | 951 | char *buf; |
2ee867dc | 952 | struct blkg_rwstat rwstat; |
636620b6 | 953 | u64 rbytes, wbytes, rios, wios, dbytes, dios; |
903d23f0 JB |
954 | size_t size = seq_get_buf(sf, &buf), off = 0; |
955 | int i; | |
956 | bool has_stats = false; | |
2ee867dc TH |
957 | |
958 | dname = blkg_dev_name(blkg); | |
959 | if (!dname) | |
960 | continue; | |
961 | ||
903d23f0 JB |
962 | /* |
963 | * Hooray string manipulation, count is the size written NOT | |
964 | * INCLUDING THE \0, so size is now count+1 less than what we | |
965 | * had before, but we want to start writing the next bit from | |
966 | * the \0 so we only add count to buf. | |
967 | */ | |
968 | off += scnprintf(buf+off, size-off, "%s ", dname); | |
969 | ||
2ee867dc TH |
970 | spin_lock_irq(blkg->q->queue_lock); |
971 | ||
972 | rwstat = blkg_rwstat_recursive_sum(blkg, NULL, | |
973 | offsetof(struct blkcg_gq, stat_bytes)); | |
974 | rbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]); | |
975 | wbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]); | |
636620b6 | 976 | dbytes = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_DISCARD]); |
2ee867dc TH |
977 | |
978 | rwstat = blkg_rwstat_recursive_sum(blkg, NULL, | |
979 | offsetof(struct blkcg_gq, stat_ios)); | |
980 | rios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_READ]); | |
981 | wios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_WRITE]); | |
636620b6 | 982 | dios = atomic64_read(&rwstat.aux_cnt[BLKG_RWSTAT_DISCARD]); |
2ee867dc TH |
983 | |
984 | spin_unlock_irq(blkg->q->queue_lock); | |
985 | ||
903d23f0 JB |
986 | if (rbytes || wbytes || rios || wios) { |
987 | has_stats = true; | |
988 | off += scnprintf(buf+off, size-off, | |
636620b6 TH |
989 | "rbytes=%llu wbytes=%llu rios=%llu wios=%llu dbytes=%llu dios=%llu", |
990 | rbytes, wbytes, rios, wios, | |
991 | dbytes, dios); | |
903d23f0 JB |
992 | } |
993 | ||
994 | if (!blkcg_debug_stats) | |
995 | goto next; | |
996 | ||
d09d8df3 JB |
997 | if (atomic_read(&blkg->use_delay)) { |
998 | has_stats = true; | |
999 | off += scnprintf(buf+off, size-off, | |
1000 | " use_delay=%d delay_nsec=%llu", | |
1001 | atomic_read(&blkg->use_delay), | |
1002 | (unsigned long long)atomic64_read(&blkg->delay_nsec)); | |
1003 | } | |
1004 | ||
903d23f0 JB |
1005 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
1006 | struct blkcg_policy *pol = blkcg_policy[i]; | |
1007 | size_t written; | |
1008 | ||
1009 | if (!blkg->pd[i] || !pol->pd_stat_fn) | |
1010 | continue; | |
1011 | ||
1012 | written = pol->pd_stat_fn(blkg->pd[i], buf+off, size-off); | |
1013 | if (written) | |
1014 | has_stats = true; | |
1015 | off += written; | |
1016 | } | |
1017 | next: | |
1018 | if (has_stats) { | |
1019 | off += scnprintf(buf+off, size-off, "\n"); | |
1020 | seq_commit(sf, off); | |
1021 | } | |
2ee867dc TH |
1022 | } |
1023 | ||
1024 | rcu_read_unlock(); | |
1025 | return 0; | |
1026 | } | |
1027 | ||
e1f3b941 | 1028 | static struct cftype blkcg_files[] = { |
2ee867dc TH |
1029 | { |
1030 | .name = "stat", | |
ca0752c5 | 1031 | .flags = CFTYPE_NOT_ON_ROOT, |
2ee867dc TH |
1032 | .seq_show = blkcg_print_stat, |
1033 | }, | |
1034 | { } /* terminate */ | |
1035 | }; | |
1036 | ||
e1f3b941 | 1037 | static struct cftype blkcg_legacy_files[] = { |
84c124da DS |
1038 | { |
1039 | .name = "reset_stats", | |
3c798398 | 1040 | .write_u64 = blkcg_reset_stats, |
22084190 | 1041 | }, |
4baf6e33 | 1042 | { } /* terminate */ |
31e4c28d VG |
1043 | }; |
1044 | ||
59b57717 DZF |
1045 | /* |
1046 | * blkcg destruction is a three-stage process. | |
1047 | * | |
1048 | * 1. Destruction starts. The blkcg_css_offline() callback is invoked | |
1049 | * which offlines writeback. Here we tie the next stage of blkg destruction | |
1050 | * to the completion of writeback associated with the blkcg. This lets us | |
1051 | * avoid punting potentially large amounts of outstanding writeback to root | |
1052 | * while maintaining any ongoing policies. The next stage is triggered when | |
1053 | * the nr_cgwbs count goes to zero. | |
1054 | * | |
1055 | * 2. When the nr_cgwbs count goes to zero, blkcg_destroy_blkgs() is called | |
1056 | * and handles the destruction of blkgs. Here the css reference held by | |
1057 | * the blkg is put back eventually allowing blkcg_css_free() to be called. | |
1058 | * This work may occur in cgwb_release_workfn() on the cgwb_release | |
1059 | * workqueue. Any submitted ios that fail to get the blkg ref will be | |
1060 | * punted to the root_blkg. | |
1061 | * | |
1062 | * 3. Once the blkcg ref count goes to zero, blkcg_css_free() is called. | |
1063 | * This finally frees the blkcg. | |
1064 | */ | |
1065 | ||
9f13ef67 | 1066 | /** |
92fb9748 | 1067 | * blkcg_css_offline - cgroup css_offline callback |
eb95419b | 1068 | * @css: css of interest |
9f13ef67 | 1069 | * |
59b57717 DZF |
1070 | * This function is called when @css is about to go away. Here the cgwbs are |
1071 | * offlined first and only once writeback associated with the blkcg has | |
1072 | * finished do we start step 2 (see above). | |
9f13ef67 | 1073 | */ |
eb95419b | 1074 | static void blkcg_css_offline(struct cgroup_subsys_state *css) |
31e4c28d | 1075 | { |
eb95419b | 1076 | struct blkcg *blkcg = css_to_blkcg(css); |
b1c35769 | 1077 | |
59b57717 DZF |
1078 | /* this prevents anyone from attaching or migrating to this blkcg */ |
1079 | wb_blkcg_offline(blkcg); | |
1080 | ||
1081 | /* put the base cgwb reference allowing step 2 to be triggered */ | |
1082 | blkcg_cgwb_put(blkcg); | |
1083 | } | |
1084 | ||
1085 | /** | |
1086 | * blkcg_destroy_blkgs - responsible for shooting down blkgs | |
1087 | * @blkcg: blkcg of interest | |
1088 | * | |
1089 | * blkgs should be removed while holding both q and blkcg locks. As blkcg lock | |
1090 | * is nested inside q lock, this function performs reverse double lock dancing. | |
1091 | * Destroying the blkgs releases the reference held on the blkcg's css allowing | |
1092 | * blkcg_css_free to eventually be called. | |
1093 | * | |
1094 | * This is the blkcg counterpart of ioc_release_fn(). | |
1095 | */ | |
1096 | void blkcg_destroy_blkgs(struct blkcg *blkcg) | |
1097 | { | |
9f13ef67 | 1098 | spin_lock_irq(&blkcg->lock); |
7ee9c562 | 1099 | |
4c699480 JQ |
1100 | while (!hlist_empty(&blkcg->blkg_list)) { |
1101 | struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first, | |
6b065462 | 1102 | struct blkcg_gq, blkcg_node); |
4c699480 JQ |
1103 | struct request_queue *q = blkg->q; |
1104 | ||
1105 | if (spin_trylock(q->queue_lock)) { | |
1106 | blkg_destroy(blkg); | |
1107 | spin_unlock(q->queue_lock); | |
1108 | } else { | |
1109 | spin_unlock_irq(&blkcg->lock); | |
1110 | cpu_relax(); | |
1111 | spin_lock_irq(&blkcg->lock); | |
1112 | } | |
1113 | } | |
6b065462 | 1114 | |
4c699480 JQ |
1115 | spin_unlock_irq(&blkcg->lock); |
1116 | } | |
1117 | ||
eb95419b | 1118 | static void blkcg_css_free(struct cgroup_subsys_state *css) |
7ee9c562 | 1119 | { |
eb95419b | 1120 | struct blkcg *blkcg = css_to_blkcg(css); |
bc915e61 | 1121 | int i; |
7ee9c562 | 1122 | |
7876f930 | 1123 | mutex_lock(&blkcg_pol_mutex); |
e4a9bde9 | 1124 | |
7876f930 | 1125 | list_del(&blkcg->all_blkcgs_node); |
7876f930 | 1126 | |
bc915e61 | 1127 | for (i = 0; i < BLKCG_MAX_POLS; i++) |
e4a9bde9 TH |
1128 | if (blkcg->cpd[i]) |
1129 | blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]); | |
1130 | ||
1131 | mutex_unlock(&blkcg_pol_mutex); | |
1132 | ||
bc915e61 | 1133 | kfree(blkcg); |
31e4c28d VG |
1134 | } |
1135 | ||
eb95419b TH |
1136 | static struct cgroup_subsys_state * |
1137 | blkcg_css_alloc(struct cgroup_subsys_state *parent_css) | |
31e4c28d | 1138 | { |
3c798398 | 1139 | struct blkcg *blkcg; |
e48453c3 AA |
1140 | struct cgroup_subsys_state *ret; |
1141 | int i; | |
31e4c28d | 1142 | |
7876f930 TH |
1143 | mutex_lock(&blkcg_pol_mutex); |
1144 | ||
eb95419b | 1145 | if (!parent_css) { |
3c798398 | 1146 | blkcg = &blkcg_root; |
bc915e61 TH |
1147 | } else { |
1148 | blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); | |
1149 | if (!blkcg) { | |
1150 | ret = ERR_PTR(-ENOMEM); | |
4c18c9e9 | 1151 | goto unlock; |
bc915e61 | 1152 | } |
e48453c3 AA |
1153 | } |
1154 | ||
1155 | for (i = 0; i < BLKCG_MAX_POLS ; i++) { | |
1156 | struct blkcg_policy *pol = blkcg_policy[i]; | |
1157 | struct blkcg_policy_data *cpd; | |
1158 | ||
1159 | /* | |
1160 | * If the policy hasn't been attached yet, wait for it | |
1161 | * to be attached before doing anything else. Otherwise, | |
1162 | * check if the policy requires any specific per-cgroup | |
1163 | * data: if it does, allocate and initialize it. | |
1164 | */ | |
e4a9bde9 | 1165 | if (!pol || !pol->cpd_alloc_fn) |
e48453c3 AA |
1166 | continue; |
1167 | ||
e4a9bde9 | 1168 | cpd = pol->cpd_alloc_fn(GFP_KERNEL); |
e48453c3 AA |
1169 | if (!cpd) { |
1170 | ret = ERR_PTR(-ENOMEM); | |
1171 | goto free_pd_blkcg; | |
1172 | } | |
81437648 TH |
1173 | blkcg->cpd[i] = cpd; |
1174 | cpd->blkcg = blkcg; | |
e48453c3 | 1175 | cpd->plid = i; |
e4a9bde9 TH |
1176 | if (pol->cpd_init_fn) |
1177 | pol->cpd_init_fn(cpd); | |
e48453c3 | 1178 | } |
31e4c28d | 1179 | |
31e4c28d | 1180 | spin_lock_init(&blkcg->lock); |
e00f4f4d | 1181 | INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT | __GFP_NOWARN); |
31e4c28d | 1182 | INIT_HLIST_HEAD(&blkcg->blkg_list); |
52ebea74 TH |
1183 | #ifdef CONFIG_CGROUP_WRITEBACK |
1184 | INIT_LIST_HEAD(&blkcg->cgwb_list); | |
59b57717 | 1185 | refcount_set(&blkcg->cgwb_refcnt, 1); |
52ebea74 | 1186 | #endif |
7876f930 TH |
1187 | list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs); |
1188 | ||
1189 | mutex_unlock(&blkcg_pol_mutex); | |
31e4c28d | 1190 | return &blkcg->css; |
e48453c3 AA |
1191 | |
1192 | free_pd_blkcg: | |
1193 | for (i--; i >= 0; i--) | |
e4a9bde9 TH |
1194 | if (blkcg->cpd[i]) |
1195 | blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]); | |
4c18c9e9 | 1196 | |
1197 | if (blkcg != &blkcg_root) | |
1198 | kfree(blkcg); | |
1199 | unlock: | |
7876f930 | 1200 | mutex_unlock(&blkcg_pol_mutex); |
e48453c3 | 1201 | return ret; |
31e4c28d VG |
1202 | } |
1203 | ||
5efd6113 TH |
1204 | /** |
1205 | * blkcg_init_queue - initialize blkcg part of request queue | |
1206 | * @q: request_queue to initialize | |
1207 | * | |
1208 | * Called from blk_alloc_queue_node(). Responsible for initializing blkcg | |
1209 | * part of new request_queue @q. | |
1210 | * | |
1211 | * RETURNS: | |
1212 | * 0 on success, -errno on failure. | |
1213 | */ | |
1214 | int blkcg_init_queue(struct request_queue *q) | |
1215 | { | |
d708f0d5 JA |
1216 | struct blkcg_gq *new_blkg, *blkg; |
1217 | bool preloaded; | |
ec13b1d6 TH |
1218 | int ret; |
1219 | ||
d708f0d5 JA |
1220 | new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL); |
1221 | if (!new_blkg) | |
1222 | return -ENOMEM; | |
1223 | ||
1224 | preloaded = !radix_tree_preload(GFP_KERNEL); | |
1225 | ||
bea54883 | 1226 | /* Make sure the root blkg exists. */ |
ec13b1d6 TH |
1227 | rcu_read_lock(); |
1228 | spin_lock_irq(q->queue_lock); | |
d708f0d5 | 1229 | blkg = blkg_create(&blkcg_root, q, new_blkg); |
901932a3 JB |
1230 | if (IS_ERR(blkg)) |
1231 | goto err_unlock; | |
1232 | q->root_blkg = blkg; | |
1233 | q->root_rl.blkg = blkg; | |
ec13b1d6 TH |
1234 | spin_unlock_irq(q->queue_lock); |
1235 | rcu_read_unlock(); | |
1236 | ||
d708f0d5 JA |
1237 | if (preloaded) |
1238 | radix_tree_preload_end(); | |
1239 | ||
d7067512 JB |
1240 | ret = blk_iolatency_init(q); |
1241 | if (ret) { | |
1242 | spin_lock_irq(q->queue_lock); | |
1243 | blkg_destroy_all(q); | |
1244 | spin_unlock_irq(q->queue_lock); | |
1245 | return ret; | |
1246 | } | |
1247 | ||
ec13b1d6 TH |
1248 | ret = blk_throtl_init(q); |
1249 | if (ret) { | |
1250 | spin_lock_irq(q->queue_lock); | |
1251 | blkg_destroy_all(q); | |
1252 | spin_unlock_irq(q->queue_lock); | |
1253 | } | |
1254 | return ret; | |
901932a3 JB |
1255 | |
1256 | err_unlock: | |
1257 | spin_unlock_irq(q->queue_lock); | |
1258 | rcu_read_unlock(); | |
1259 | if (preloaded) | |
1260 | radix_tree_preload_end(); | |
1261 | return PTR_ERR(blkg); | |
5efd6113 TH |
1262 | } |
1263 | ||
1264 | /** | |
1265 | * blkcg_drain_queue - drain blkcg part of request_queue | |
1266 | * @q: request_queue to drain | |
1267 | * | |
1268 | * Called from blk_drain_queue(). Responsible for draining blkcg part. | |
1269 | */ | |
1270 | void blkcg_drain_queue(struct request_queue *q) | |
1271 | { | |
1272 | lockdep_assert_held(q->queue_lock); | |
1273 | ||
0b462c89 TH |
1274 | /* |
1275 | * @q could be exiting and already have destroyed all blkgs as | |
1276 | * indicated by NULL root_blkg. If so, don't confuse policies. | |
1277 | */ | |
1278 | if (!q->root_blkg) | |
1279 | return; | |
1280 | ||
5efd6113 TH |
1281 | blk_throtl_drain(q); |
1282 | } | |
1283 | ||
1284 | /** | |
1285 | * blkcg_exit_queue - exit and release blkcg part of request_queue | |
1286 | * @q: request_queue being released | |
1287 | * | |
1288 | * Called from blk_release_queue(). Responsible for exiting blkcg part. | |
1289 | */ | |
1290 | void blkcg_exit_queue(struct request_queue *q) | |
1291 | { | |
6d18b008 | 1292 | spin_lock_irq(q->queue_lock); |
3c96cb32 | 1293 | blkg_destroy_all(q); |
6d18b008 TH |
1294 | spin_unlock_irq(q->queue_lock); |
1295 | ||
5efd6113 TH |
1296 | blk_throtl_exit(q); |
1297 | } | |
1298 | ||
31e4c28d VG |
1299 | /* |
1300 | * We cannot support shared io contexts, as we have no mean to support | |
1301 | * two tasks with the same ioc in two different groups without major rework | |
1302 | * of the main cic data structures. For now we allow a task to change | |
1303 | * its cgroup only if it's the only owner of its ioc. | |
1304 | */ | |
1f7dd3e5 | 1305 | static int blkcg_can_attach(struct cgroup_taskset *tset) |
31e4c28d | 1306 | { |
bb9d97b6 | 1307 | struct task_struct *task; |
1f7dd3e5 | 1308 | struct cgroup_subsys_state *dst_css; |
31e4c28d VG |
1309 | struct io_context *ioc; |
1310 | int ret = 0; | |
1311 | ||
1312 | /* task_lock() is needed to avoid races with exit_io_context() */ | |
1f7dd3e5 | 1313 | cgroup_taskset_for_each(task, dst_css, tset) { |
bb9d97b6 TH |
1314 | task_lock(task); |
1315 | ioc = task->io_context; | |
1316 | if (ioc && atomic_read(&ioc->nr_tasks) > 1) | |
1317 | ret = -EINVAL; | |
1318 | task_unlock(task); | |
1319 | if (ret) | |
1320 | break; | |
1321 | } | |
31e4c28d VG |
1322 | return ret; |
1323 | } | |
1324 | ||
69d7fde5 TH |
1325 | static void blkcg_bind(struct cgroup_subsys_state *root_css) |
1326 | { | |
1327 | int i; | |
1328 | ||
1329 | mutex_lock(&blkcg_pol_mutex); | |
1330 | ||
1331 | for (i = 0; i < BLKCG_MAX_POLS; i++) { | |
1332 | struct blkcg_policy *pol = blkcg_policy[i]; | |
1333 | struct blkcg *blkcg; | |
1334 | ||
1335 | if (!pol || !pol->cpd_bind_fn) | |
1336 | continue; | |
1337 | ||
1338 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) | |
1339 | if (blkcg->cpd[pol->plid]) | |
1340 | pol->cpd_bind_fn(blkcg->cpd[pol->plid]); | |
1341 | } | |
1342 | mutex_unlock(&blkcg_pol_mutex); | |
1343 | } | |
1344 | ||
d09d8df3 JB |
1345 | static void blkcg_exit(struct task_struct *tsk) |
1346 | { | |
1347 | if (tsk->throttle_queue) | |
1348 | blk_put_queue(tsk->throttle_queue); | |
1349 | tsk->throttle_queue = NULL; | |
1350 | } | |
1351 | ||
c165b3e3 | 1352 | struct cgroup_subsys io_cgrp_subsys = { |
92fb9748 TH |
1353 | .css_alloc = blkcg_css_alloc, |
1354 | .css_offline = blkcg_css_offline, | |
1355 | .css_free = blkcg_css_free, | |
3c798398 | 1356 | .can_attach = blkcg_can_attach, |
69d7fde5 | 1357 | .bind = blkcg_bind, |
2ee867dc | 1358 | .dfl_cftypes = blkcg_files, |
880f50e2 | 1359 | .legacy_cftypes = blkcg_legacy_files, |
c165b3e3 | 1360 | .legacy_name = "blkio", |
d09d8df3 | 1361 | .exit = blkcg_exit, |
1ced953b TH |
1362 | #ifdef CONFIG_MEMCG |
1363 | /* | |
1364 | * This ensures that, if available, memcg is automatically enabled | |
1365 | * together on the default hierarchy so that the owner cgroup can | |
1366 | * be retrieved from writeback pages. | |
1367 | */ | |
1368 | .depends_on = 1 << memory_cgrp_id, | |
1369 | #endif | |
676f7c8f | 1370 | }; |
c165b3e3 | 1371 | EXPORT_SYMBOL_GPL(io_cgrp_subsys); |
676f7c8f | 1372 | |
a2b1693b TH |
1373 | /** |
1374 | * blkcg_activate_policy - activate a blkcg policy on a request_queue | |
1375 | * @q: request_queue of interest | |
1376 | * @pol: blkcg policy to activate | |
1377 | * | |
1378 | * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through | |
1379 | * bypass mode to populate its blkgs with policy_data for @pol. | |
1380 | * | |
1381 | * Activation happens with @q bypassed, so nobody would be accessing blkgs | |
1382 | * from IO path. Update of each blkg is protected by both queue and blkcg | |
1383 | * locks so that holding either lock and testing blkcg_policy_enabled() is | |
1384 | * always enough for dereferencing policy data. | |
1385 | * | |
1386 | * The caller is responsible for synchronizing [de]activations and policy | |
1387 | * [un]registerations. Returns 0 on success, -errno on failure. | |
1388 | */ | |
1389 | int blkcg_activate_policy(struct request_queue *q, | |
3c798398 | 1390 | const struct blkcg_policy *pol) |
a2b1693b | 1391 | { |
4c55f4f9 | 1392 | struct blkg_policy_data *pd_prealloc = NULL; |
ec13b1d6 | 1393 | struct blkcg_gq *blkg; |
4c55f4f9 | 1394 | int ret; |
a2b1693b TH |
1395 | |
1396 | if (blkcg_policy_enabled(q, pol)) | |
1397 | return 0; | |
1398 | ||
38dbb7dd | 1399 | if (q->mq_ops) |
bd166ef1 | 1400 | blk_mq_freeze_queue(q); |
38dbb7dd | 1401 | else |
bd166ef1 | 1402 | blk_queue_bypass_start(q); |
4c55f4f9 TH |
1403 | pd_prealloc: |
1404 | if (!pd_prealloc) { | |
001bea73 | 1405 | pd_prealloc = pol->pd_alloc_fn(GFP_KERNEL, q->node); |
4c55f4f9 | 1406 | if (!pd_prealloc) { |
a2b1693b | 1407 | ret = -ENOMEM; |
4c55f4f9 | 1408 | goto out_bypass_end; |
a2b1693b | 1409 | } |
a2b1693b TH |
1410 | } |
1411 | ||
a2b1693b TH |
1412 | spin_lock_irq(q->queue_lock); |
1413 | ||
1414 | list_for_each_entry(blkg, &q->blkg_list, q_node) { | |
4c55f4f9 TH |
1415 | struct blkg_policy_data *pd; |
1416 | ||
1417 | if (blkg->pd[pol->plid]) | |
1418 | continue; | |
a2b1693b | 1419 | |
e00f4f4d | 1420 | pd = pol->pd_alloc_fn(GFP_NOWAIT | __GFP_NOWARN, q->node); |
4c55f4f9 TH |
1421 | if (!pd) |
1422 | swap(pd, pd_prealloc); | |
1423 | if (!pd) { | |
1424 | spin_unlock_irq(q->queue_lock); | |
1425 | goto pd_prealloc; | |
1426 | } | |
a2b1693b TH |
1427 | |
1428 | blkg->pd[pol->plid] = pd; | |
1429 | pd->blkg = blkg; | |
b276a876 | 1430 | pd->plid = pol->plid; |
3e418710 | 1431 | if (pol->pd_init_fn) |
a9520cd6 | 1432 | pol->pd_init_fn(pd); |
a2b1693b TH |
1433 | } |
1434 | ||
1435 | __set_bit(pol->plid, q->blkcg_pols); | |
1436 | ret = 0; | |
4c55f4f9 | 1437 | |
a2b1693b | 1438 | spin_unlock_irq(q->queue_lock); |
4c55f4f9 | 1439 | out_bypass_end: |
38dbb7dd | 1440 | if (q->mq_ops) |
bd166ef1 | 1441 | blk_mq_unfreeze_queue(q); |
38dbb7dd | 1442 | else |
bd166ef1 | 1443 | blk_queue_bypass_end(q); |
001bea73 TH |
1444 | if (pd_prealloc) |
1445 | pol->pd_free_fn(pd_prealloc); | |
a2b1693b TH |
1446 | return ret; |
1447 | } | |
1448 | EXPORT_SYMBOL_GPL(blkcg_activate_policy); | |
1449 | ||
1450 | /** | |
1451 | * blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue | |
1452 | * @q: request_queue of interest | |
1453 | * @pol: blkcg policy to deactivate | |
1454 | * | |
1455 | * Deactivate @pol on @q. Follows the same synchronization rules as | |
1456 | * blkcg_activate_policy(). | |
1457 | */ | |
1458 | void blkcg_deactivate_policy(struct request_queue *q, | |
3c798398 | 1459 | const struct blkcg_policy *pol) |
a2b1693b | 1460 | { |
3c798398 | 1461 | struct blkcg_gq *blkg; |
a2b1693b TH |
1462 | |
1463 | if (!blkcg_policy_enabled(q, pol)) | |
1464 | return; | |
1465 | ||
38dbb7dd | 1466 | if (q->mq_ops) |
bd166ef1 | 1467 | blk_mq_freeze_queue(q); |
38dbb7dd | 1468 | else |
bd166ef1 JA |
1469 | blk_queue_bypass_start(q); |
1470 | ||
a2b1693b TH |
1471 | spin_lock_irq(q->queue_lock); |
1472 | ||
1473 | __clear_bit(pol->plid, q->blkcg_pols); | |
1474 | ||
1475 | list_for_each_entry(blkg, &q->blkg_list, q_node) { | |
001bea73 | 1476 | if (blkg->pd[pol->plid]) { |
6b065462 | 1477 | if (pol->pd_offline_fn) |
a9520cd6 | 1478 | pol->pd_offline_fn(blkg->pd[pol->plid]); |
001bea73 TH |
1479 | pol->pd_free_fn(blkg->pd[pol->plid]); |
1480 | blkg->pd[pol->plid] = NULL; | |
1481 | } | |
a2b1693b TH |
1482 | } |
1483 | ||
1484 | spin_unlock_irq(q->queue_lock); | |
bd166ef1 | 1485 | |
38dbb7dd | 1486 | if (q->mq_ops) |
bd166ef1 | 1487 | blk_mq_unfreeze_queue(q); |
38dbb7dd | 1488 | else |
bd166ef1 | 1489 | blk_queue_bypass_end(q); |
a2b1693b TH |
1490 | } |
1491 | EXPORT_SYMBOL_GPL(blkcg_deactivate_policy); | |
1492 | ||
8bd435b3 | 1493 | /** |
3c798398 TH |
1494 | * blkcg_policy_register - register a blkcg policy |
1495 | * @pol: blkcg policy to register | |
8bd435b3 | 1496 | * |
3c798398 TH |
1497 | * Register @pol with blkcg core. Might sleep and @pol may be modified on |
1498 | * successful registration. Returns 0 on success and -errno on failure. | |
8bd435b3 | 1499 | */ |
d5bf0291 | 1500 | int blkcg_policy_register(struct blkcg_policy *pol) |
3e252066 | 1501 | { |
06b285bd | 1502 | struct blkcg *blkcg; |
8bd435b3 | 1503 | int i, ret; |
e8989fae | 1504 | |
838f13bf | 1505 | mutex_lock(&blkcg_pol_register_mutex); |
bc0d6501 TH |
1506 | mutex_lock(&blkcg_pol_mutex); |
1507 | ||
8bd435b3 TH |
1508 | /* find an empty slot */ |
1509 | ret = -ENOSPC; | |
1510 | for (i = 0; i < BLKCG_MAX_POLS; i++) | |
3c798398 | 1511 | if (!blkcg_policy[i]) |
8bd435b3 | 1512 | break; |
01c5f85a JA |
1513 | if (i >= BLKCG_MAX_POLS) { |
1514 | pr_warn("blkcg_policy_register: BLKCG_MAX_POLS too small\n"); | |
838f13bf | 1515 | goto err_unlock; |
01c5f85a | 1516 | } |
035d10b2 | 1517 | |
e8401073 | 1518 | /* Make sure cpd/pd_alloc_fn and cpd/pd_free_fn in pairs */ |
1519 | if ((!pol->cpd_alloc_fn ^ !pol->cpd_free_fn) || | |
1520 | (!pol->pd_alloc_fn ^ !pol->pd_free_fn)) | |
1521 | goto err_unlock; | |
1522 | ||
06b285bd | 1523 | /* register @pol */ |
3c798398 | 1524 | pol->plid = i; |
06b285bd TH |
1525 | blkcg_policy[pol->plid] = pol; |
1526 | ||
1527 | /* allocate and install cpd's */ | |
e4a9bde9 | 1528 | if (pol->cpd_alloc_fn) { |
06b285bd TH |
1529 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
1530 | struct blkcg_policy_data *cpd; | |
1531 | ||
e4a9bde9 | 1532 | cpd = pol->cpd_alloc_fn(GFP_KERNEL); |
bbb427e3 | 1533 | if (!cpd) |
06b285bd | 1534 | goto err_free_cpds; |
06b285bd | 1535 | |
81437648 TH |
1536 | blkcg->cpd[pol->plid] = cpd; |
1537 | cpd->blkcg = blkcg; | |
06b285bd | 1538 | cpd->plid = pol->plid; |
81437648 | 1539 | pol->cpd_init_fn(cpd); |
06b285bd TH |
1540 | } |
1541 | } | |
1542 | ||
838f13bf | 1543 | mutex_unlock(&blkcg_pol_mutex); |
8bd435b3 | 1544 | |
8bd435b3 | 1545 | /* everything is in place, add intf files for the new policy */ |
2ee867dc TH |
1546 | if (pol->dfl_cftypes) |
1547 | WARN_ON(cgroup_add_dfl_cftypes(&io_cgrp_subsys, | |
1548 | pol->dfl_cftypes)); | |
880f50e2 | 1549 | if (pol->legacy_cftypes) |
c165b3e3 | 1550 | WARN_ON(cgroup_add_legacy_cftypes(&io_cgrp_subsys, |
880f50e2 | 1551 | pol->legacy_cftypes)); |
838f13bf TH |
1552 | mutex_unlock(&blkcg_pol_register_mutex); |
1553 | return 0; | |
1554 | ||
06b285bd | 1555 | err_free_cpds: |
58a9edce | 1556 | if (pol->cpd_free_fn) { |
06b285bd | 1557 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
e4a9bde9 TH |
1558 | if (blkcg->cpd[pol->plid]) { |
1559 | pol->cpd_free_fn(blkcg->cpd[pol->plid]); | |
1560 | blkcg->cpd[pol->plid] = NULL; | |
1561 | } | |
06b285bd TH |
1562 | } |
1563 | } | |
1564 | blkcg_policy[pol->plid] = NULL; | |
838f13bf | 1565 | err_unlock: |
bc0d6501 | 1566 | mutex_unlock(&blkcg_pol_mutex); |
838f13bf | 1567 | mutex_unlock(&blkcg_pol_register_mutex); |
8bd435b3 | 1568 | return ret; |
3e252066 | 1569 | } |
3c798398 | 1570 | EXPORT_SYMBOL_GPL(blkcg_policy_register); |
3e252066 | 1571 | |
8bd435b3 | 1572 | /** |
3c798398 TH |
1573 | * blkcg_policy_unregister - unregister a blkcg policy |
1574 | * @pol: blkcg policy to unregister | |
8bd435b3 | 1575 | * |
3c798398 | 1576 | * Undo blkcg_policy_register(@pol). Might sleep. |
8bd435b3 | 1577 | */ |
3c798398 | 1578 | void blkcg_policy_unregister(struct blkcg_policy *pol) |
3e252066 | 1579 | { |
06b285bd TH |
1580 | struct blkcg *blkcg; |
1581 | ||
838f13bf | 1582 | mutex_lock(&blkcg_pol_register_mutex); |
bc0d6501 | 1583 | |
3c798398 | 1584 | if (WARN_ON(blkcg_policy[pol->plid] != pol)) |
8bd435b3 TH |
1585 | goto out_unlock; |
1586 | ||
1587 | /* kill the intf files first */ | |
2ee867dc TH |
1588 | if (pol->dfl_cftypes) |
1589 | cgroup_rm_cftypes(pol->dfl_cftypes); | |
880f50e2 TH |
1590 | if (pol->legacy_cftypes) |
1591 | cgroup_rm_cftypes(pol->legacy_cftypes); | |
44ea53de | 1592 | |
06b285bd | 1593 | /* remove cpds and unregister */ |
838f13bf | 1594 | mutex_lock(&blkcg_pol_mutex); |
06b285bd | 1595 | |
58a9edce | 1596 | if (pol->cpd_free_fn) { |
06b285bd | 1597 | list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
e4a9bde9 TH |
1598 | if (blkcg->cpd[pol->plid]) { |
1599 | pol->cpd_free_fn(blkcg->cpd[pol->plid]); | |
1600 | blkcg->cpd[pol->plid] = NULL; | |
1601 | } | |
06b285bd TH |
1602 | } |
1603 | } | |
3c798398 | 1604 | blkcg_policy[pol->plid] = NULL; |
06b285bd | 1605 | |
bc0d6501 | 1606 | mutex_unlock(&blkcg_pol_mutex); |
838f13bf TH |
1607 | out_unlock: |
1608 | mutex_unlock(&blkcg_pol_register_mutex); | |
3e252066 | 1609 | } |
3c798398 | 1610 | EXPORT_SYMBOL_GPL(blkcg_policy_unregister); |
903d23f0 | 1611 | |
d09d8df3 JB |
1612 | /* |
1613 | * Scale the accumulated delay based on how long it has been since we updated | |
1614 | * the delay. We only call this when we are adding delay, in case it's been a | |
1615 | * while since we added delay, and when we are checking to see if we need to | |
1616 | * delay a task, to account for any delays that may have occurred. | |
1617 | */ | |
1618 | static void blkcg_scale_delay(struct blkcg_gq *blkg, u64 now) | |
1619 | { | |
1620 | u64 old = atomic64_read(&blkg->delay_start); | |
1621 | ||
1622 | /* | |
1623 | * We only want to scale down every second. The idea here is that we | |
1624 | * want to delay people for min(delay_nsec, NSEC_PER_SEC) in a certain | |
1625 | * time window. We only want to throttle tasks for recent delay that | |
1626 | * has occurred, in 1 second time windows since that's the maximum | |
1627 | * things can be throttled. We save the current delay window in | |
1628 | * blkg->last_delay so we know what amount is still left to be charged | |
1629 | * to the blkg from this point onward. blkg->last_use keeps track of | |
1630 | * the use_delay counter. The idea is if we're unthrottling the blkg we | |
1631 | * are ok with whatever is happening now, and we can take away more of | |
1632 | * the accumulated delay as we've already throttled enough that | |
1633 | * everybody is happy with their IO latencies. | |
1634 | */ | |
1635 | if (time_before64(old + NSEC_PER_SEC, now) && | |
1636 | atomic64_cmpxchg(&blkg->delay_start, old, now) == old) { | |
1637 | u64 cur = atomic64_read(&blkg->delay_nsec); | |
1638 | u64 sub = min_t(u64, blkg->last_delay, now - old); | |
1639 | int cur_use = atomic_read(&blkg->use_delay); | |
1640 | ||
1641 | /* | |
1642 | * We've been unthrottled, subtract a larger chunk of our | |
1643 | * accumulated delay. | |
1644 | */ | |
1645 | if (cur_use < blkg->last_use) | |
1646 | sub = max_t(u64, sub, blkg->last_delay >> 1); | |
1647 | ||
1648 | /* | |
1649 | * This shouldn't happen, but handle it anyway. Our delay_nsec | |
1650 | * should only ever be growing except here where we subtract out | |
1651 | * min(last_delay, 1 second), but lord knows bugs happen and I'd | |
1652 | * rather not end up with negative numbers. | |
1653 | */ | |
1654 | if (unlikely(cur < sub)) { | |
1655 | atomic64_set(&blkg->delay_nsec, 0); | |
1656 | blkg->last_delay = 0; | |
1657 | } else { | |
1658 | atomic64_sub(sub, &blkg->delay_nsec); | |
1659 | blkg->last_delay = cur - sub; | |
1660 | } | |
1661 | blkg->last_use = cur_use; | |
1662 | } | |
1663 | } | |
1664 | ||
1665 | /* | |
1666 | * This is called when we want to actually walk up the hierarchy and check to | |
1667 | * see if we need to throttle, and then actually throttle if there is some | |
1668 | * accumulated delay. This should only be called upon return to user space so | |
1669 | * we're not holding some lock that would induce a priority inversion. | |
1670 | */ | |
1671 | static void blkcg_maybe_throttle_blkg(struct blkcg_gq *blkg, bool use_memdelay) | |
1672 | { | |
1673 | u64 now = ktime_to_ns(ktime_get()); | |
1674 | u64 exp; | |
1675 | u64 delay_nsec = 0; | |
1676 | int tok; | |
1677 | ||
1678 | while (blkg->parent) { | |
1679 | if (atomic_read(&blkg->use_delay)) { | |
1680 | blkcg_scale_delay(blkg, now); | |
1681 | delay_nsec = max_t(u64, delay_nsec, | |
1682 | atomic64_read(&blkg->delay_nsec)); | |
1683 | } | |
1684 | blkg = blkg->parent; | |
1685 | } | |
1686 | ||
1687 | if (!delay_nsec) | |
1688 | return; | |
1689 | ||
1690 | /* | |
1691 | * Let's not sleep for all eternity if we've amassed a huge delay. | |
1692 | * Swapping or metadata IO can accumulate 10's of seconds worth of | |
1693 | * delay, and we want userspace to be able to do _something_ so cap the | |
1694 | * delays at 1 second. If there's 10's of seconds worth of delay then | |
1695 | * the tasks will be delayed for 1 second for every syscall. | |
1696 | */ | |
1697 | delay_nsec = min_t(u64, delay_nsec, 250 * NSEC_PER_MSEC); | |
1698 | ||
1699 | /* | |
1700 | * TODO: the use_memdelay flag is going to be for the upcoming psi stuff | |
1701 | * that hasn't landed upstream yet. Once that stuff is in place we need | |
1702 | * to do a psi_memstall_enter/leave if memdelay is set. | |
1703 | */ | |
1704 | ||
1705 | exp = ktime_add_ns(now, delay_nsec); | |
1706 | tok = io_schedule_prepare(); | |
1707 | do { | |
1708 | __set_current_state(TASK_KILLABLE); | |
1709 | if (!schedule_hrtimeout(&exp, HRTIMER_MODE_ABS)) | |
1710 | break; | |
1711 | } while (!fatal_signal_pending(current)); | |
1712 | io_schedule_finish(tok); | |
1713 | } | |
1714 | ||
1715 | /** | |
1716 | * blkcg_maybe_throttle_current - throttle the current task if it has been marked | |
1717 | * | |
1718 | * This is only called if we've been marked with set_notify_resume(). Obviously | |
1719 | * we can be set_notify_resume() for reasons other than blkcg throttling, so we | |
1720 | * check to see if current->throttle_queue is set and if not this doesn't do | |
1721 | * anything. This should only ever be called by the resume code, it's not meant | |
1722 | * to be called by people willy-nilly as it will actually do the work to | |
1723 | * throttle the task if it is setup for throttling. | |
1724 | */ | |
1725 | void blkcg_maybe_throttle_current(void) | |
1726 | { | |
1727 | struct request_queue *q = current->throttle_queue; | |
1728 | struct cgroup_subsys_state *css; | |
1729 | struct blkcg *blkcg; | |
1730 | struct blkcg_gq *blkg; | |
1731 | bool use_memdelay = current->use_memdelay; | |
1732 | ||
1733 | if (!q) | |
1734 | return; | |
1735 | ||
1736 | current->throttle_queue = NULL; | |
1737 | current->use_memdelay = false; | |
1738 | ||
1739 | rcu_read_lock(); | |
1740 | css = kthread_blkcg(); | |
1741 | if (css) | |
1742 | blkcg = css_to_blkcg(css); | |
1743 | else | |
1744 | blkcg = css_to_blkcg(task_css(current, io_cgrp_id)); | |
1745 | ||
1746 | if (!blkcg) | |
1747 | goto out; | |
1748 | blkg = blkg_lookup(blkcg, q); | |
1749 | if (!blkg) | |
1750 | goto out; | |
1751 | blkg = blkg_try_get(blkg); | |
1752 | if (!blkg) | |
1753 | goto out; | |
1754 | rcu_read_unlock(); | |
d09d8df3 JB |
1755 | |
1756 | blkcg_maybe_throttle_blkg(blkg, use_memdelay); | |
1757 | blkg_put(blkg); | |
cc7ecc25 | 1758 | blk_put_queue(q); |
d09d8df3 JB |
1759 | return; |
1760 | out: | |
1761 | rcu_read_unlock(); | |
1762 | blk_put_queue(q); | |
1763 | } | |
1764 | EXPORT_SYMBOL_GPL(blkcg_maybe_throttle_current); | |
1765 | ||
1766 | /** | |
1767 | * blkcg_schedule_throttle - this task needs to check for throttling | |
1768 | * @q - the request queue IO was submitted on | |
1769 | * @use_memdelay - do we charge this to memory delay for PSI | |
1770 | * | |
1771 | * This is called by the IO controller when we know there's delay accumulated | |
1772 | * for the blkg for this task. We do not pass the blkg because there are places | |
1773 | * we call this that may not have that information, the swapping code for | |
1774 | * instance will only have a request_queue at that point. This set's the | |
1775 | * notify_resume for the task to check and see if it requires throttling before | |
1776 | * returning to user space. | |
1777 | * | |
1778 | * We will only schedule once per syscall. You can call this over and over | |
1779 | * again and it will only do the check once upon return to user space, and only | |
1780 | * throttle once. If the task needs to be throttled again it'll need to be | |
1781 | * re-set at the next time we see the task. | |
1782 | */ | |
1783 | void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay) | |
1784 | { | |
1785 | if (unlikely(current->flags & PF_KTHREAD)) | |
1786 | return; | |
1787 | ||
1788 | if (!blk_get_queue(q)) | |
1789 | return; | |
1790 | ||
1791 | if (current->throttle_queue) | |
1792 | blk_put_queue(current->throttle_queue); | |
1793 | current->throttle_queue = q; | |
1794 | if (use_memdelay) | |
1795 | current->use_memdelay = use_memdelay; | |
1796 | set_notify_resume(current); | |
1797 | } | |
1798 | EXPORT_SYMBOL_GPL(blkcg_schedule_throttle); | |
1799 | ||
1800 | /** | |
1801 | * blkcg_add_delay - add delay to this blkg | |
1802 | * @now - the current time in nanoseconds | |
1803 | * @delta - how many nanoseconds of delay to add | |
1804 | * | |
1805 | * Charge @delta to the blkg's current delay accumulation. This is used to | |
1806 | * throttle tasks if an IO controller thinks we need more throttling. | |
1807 | */ | |
1808 | void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta) | |
1809 | { | |
1810 | blkcg_scale_delay(blkg, now); | |
1811 | atomic64_add(delta, &blkg->delay_nsec); | |
1812 | } | |
1813 | EXPORT_SYMBOL_GPL(blkcg_add_delay); | |
1814 | ||
903d23f0 JB |
1815 | module_param(blkcg_debug_stats, bool, 0644); |
1816 | MODULE_PARM_DESC(blkcg_debug_stats, "True if you want debug stats, false if not"); |