Commit | Line | Data |
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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> | |
12 | */ | |
13 | #include <linux/ioprio.h> | |
22084190 | 14 | #include <linux/kdev_t.h> |
9d6a986c | 15 | #include <linux/module.h> |
accee785 | 16 | #include <linux/err.h> |
9195291e | 17 | #include <linux/blkdev.h> |
5a0e3ad6 | 18 | #include <linux/slab.h> |
34d0f179 | 19 | #include <linux/genhd.h> |
72e06c25 | 20 | #include <linux/delay.h> |
9a9e8a26 | 21 | #include <linux/atomic.h> |
72e06c25 | 22 | #include "blk-cgroup.h" |
5efd6113 | 23 | #include "blk.h" |
3e252066 | 24 | |
84c124da DS |
25 | #define MAX_KEY_LEN 100 |
26 | ||
bc0d6501 | 27 | static DEFINE_MUTEX(blkcg_pol_mutex); |
923adde1 | 28 | |
3c798398 TH |
29 | struct blkcg blkcg_root = { .cfq_weight = 2 * CFQ_WEIGHT_DEFAULT }; |
30 | EXPORT_SYMBOL_GPL(blkcg_root); | |
9d6a986c | 31 | |
3c798398 | 32 | static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS]; |
035d10b2 | 33 | |
3c798398 | 34 | struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup) |
31e4c28d VG |
35 | { |
36 | return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id), | |
3c798398 | 37 | struct blkcg, css); |
31e4c28d | 38 | } |
3c798398 | 39 | EXPORT_SYMBOL_GPL(cgroup_to_blkcg); |
31e4c28d | 40 | |
3c798398 | 41 | static struct blkcg *task_blkcg(struct task_struct *tsk) |
70087dc3 VG |
42 | { |
43 | return container_of(task_subsys_state(tsk, blkio_subsys_id), | |
3c798398 | 44 | struct blkcg, css); |
70087dc3 | 45 | } |
4f85cb96 | 46 | |
3c798398 | 47 | struct blkcg *bio_blkcg(struct bio *bio) |
4f85cb96 TH |
48 | { |
49 | if (bio && bio->bi_css) | |
3c798398 TH |
50 | return container_of(bio->bi_css, struct blkcg, css); |
51 | return task_blkcg(current); | |
4f85cb96 | 52 | } |
3c798398 | 53 | EXPORT_SYMBOL_GPL(bio_blkcg); |
70087dc3 | 54 | |
a2b1693b | 55 | static bool blkcg_policy_enabled(struct request_queue *q, |
3c798398 | 56 | const struct blkcg_policy *pol) |
a2b1693b TH |
57 | { |
58 | return pol && test_bit(pol->plid, q->blkcg_pols); | |
59 | } | |
60 | ||
0381411e TH |
61 | /** |
62 | * blkg_free - free a blkg | |
63 | * @blkg: blkg to free | |
64 | * | |
65 | * Free @blkg which may be partially allocated. | |
66 | */ | |
3c798398 | 67 | static void blkg_free(struct blkcg_gq *blkg) |
0381411e | 68 | { |
e8989fae | 69 | int i; |
549d3aa8 TH |
70 | |
71 | if (!blkg) | |
72 | return; | |
73 | ||
8bd435b3 | 74 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
3c798398 | 75 | struct blkcg_policy *pol = blkcg_policy[i]; |
e8989fae TH |
76 | struct blkg_policy_data *pd = blkg->pd[i]; |
77 | ||
9ade5ea4 TH |
78 | if (!pd) |
79 | continue; | |
80 | ||
f9fcc2d3 TH |
81 | if (pol && pol->pd_exit_fn) |
82 | pol->pd_exit_fn(blkg); | |
9ade5ea4 | 83 | |
9ade5ea4 | 84 | kfree(pd); |
0381411e | 85 | } |
e8989fae | 86 | |
549d3aa8 | 87 | kfree(blkg); |
0381411e TH |
88 | } |
89 | ||
90 | /** | |
91 | * blkg_alloc - allocate a blkg | |
92 | * @blkcg: block cgroup the new blkg is associated with | |
93 | * @q: request_queue the new blkg is associated with | |
0381411e | 94 | * |
e8989fae | 95 | * Allocate a new blkg assocating @blkcg and @q. |
0381411e | 96 | */ |
3c798398 | 97 | static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q) |
0381411e | 98 | { |
3c798398 | 99 | struct blkcg_gq *blkg; |
e8989fae | 100 | int i; |
0381411e TH |
101 | |
102 | /* alloc and init base part */ | |
103 | blkg = kzalloc_node(sizeof(*blkg), GFP_ATOMIC, q->node); | |
104 | if (!blkg) | |
105 | return NULL; | |
106 | ||
c875f4d0 | 107 | blkg->q = q; |
e8989fae | 108 | INIT_LIST_HEAD(&blkg->q_node); |
0381411e | 109 | blkg->blkcg = blkcg; |
1adaf3dd | 110 | blkg->refcnt = 1; |
0381411e | 111 | |
8bd435b3 | 112 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
3c798398 | 113 | struct blkcg_policy *pol = blkcg_policy[i]; |
e8989fae | 114 | struct blkg_policy_data *pd; |
0381411e | 115 | |
a2b1693b | 116 | if (!blkcg_policy_enabled(q, pol)) |
e8989fae TH |
117 | continue; |
118 | ||
119 | /* alloc per-policy data and attach it to blkg */ | |
f95a04af | 120 | pd = kzalloc_node(pol->pd_size, GFP_ATOMIC, q->node); |
e8989fae TH |
121 | if (!pd) { |
122 | blkg_free(blkg); | |
123 | return NULL; | |
124 | } | |
549d3aa8 | 125 | |
e8989fae TH |
126 | blkg->pd[i] = pd; |
127 | pd->blkg = blkg; | |
e8989fae | 128 | |
9b2ea86b | 129 | /* invoke per-policy init */ |
a2b1693b | 130 | if (blkcg_policy_enabled(blkg->q, pol)) |
f9fcc2d3 | 131 | pol->pd_init_fn(blkg); |
e8989fae TH |
132 | } |
133 | ||
0381411e TH |
134 | return blkg; |
135 | } | |
136 | ||
3c798398 TH |
137 | static struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, |
138 | struct request_queue *q) | |
80fd9979 | 139 | { |
3c798398 | 140 | struct blkcg_gq *blkg; |
80fd9979 | 141 | |
a637120e TH |
142 | blkg = rcu_dereference(blkcg->blkg_hint); |
143 | if (blkg && blkg->q == q) | |
144 | return blkg; | |
145 | ||
146 | /* | |
147 | * Hint didn't match. Look up from the radix tree. Note that we | |
148 | * may not be holding queue_lock and thus are not sure whether | |
149 | * @blkg from blkg_tree has already been removed or not, so we | |
150 | * can't update hint to the lookup result. Leave it to the caller. | |
151 | */ | |
152 | blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); | |
153 | if (blkg && blkg->q == q) | |
154 | return blkg; | |
155 | ||
80fd9979 TH |
156 | return NULL; |
157 | } | |
158 | ||
159 | /** | |
160 | * blkg_lookup - lookup blkg for the specified blkcg - q pair | |
161 | * @blkcg: blkcg of interest | |
162 | * @q: request_queue of interest | |
163 | * | |
164 | * Lookup blkg for the @blkcg - @q pair. This function should be called | |
165 | * under RCU read lock and is guaranteed to return %NULL if @q is bypassing | |
166 | * - see blk_queue_bypass_start() for details. | |
167 | */ | |
3c798398 | 168 | struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q) |
80fd9979 TH |
169 | { |
170 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
171 | ||
172 | if (unlikely(blk_queue_bypass(q))) | |
173 | return NULL; | |
174 | return __blkg_lookup(blkcg, q); | |
175 | } | |
176 | EXPORT_SYMBOL_GPL(blkg_lookup); | |
177 | ||
3c798398 TH |
178 | static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg, |
179 | struct request_queue *q) | |
cd1604fa | 180 | __releases(q->queue_lock) __acquires(q->queue_lock) |
5624a4e4 | 181 | { |
3c798398 | 182 | struct blkcg_gq *blkg; |
496fb780 | 183 | int ret; |
5624a4e4 | 184 | |
cd1604fa TH |
185 | WARN_ON_ONCE(!rcu_read_lock_held()); |
186 | lockdep_assert_held(q->queue_lock); | |
187 | ||
a637120e | 188 | /* lookup and update hint on success, see __blkg_lookup() for details */ |
80fd9979 | 189 | blkg = __blkg_lookup(blkcg, q); |
a637120e TH |
190 | if (blkg) { |
191 | rcu_assign_pointer(blkcg->blkg_hint, blkg); | |
cd1604fa | 192 | return blkg; |
a637120e | 193 | } |
cd1604fa | 194 | |
7ee9c562 | 195 | /* blkg holds a reference to blkcg */ |
cd1604fa TH |
196 | if (!css_tryget(&blkcg->css)) |
197 | return ERR_PTR(-EINVAL); | |
198 | ||
496fb780 TH |
199 | /* allocate */ |
200 | ret = -ENOMEM; | |
1cd9e039 | 201 | blkg = blkg_alloc(blkcg, q); |
496fb780 TH |
202 | if (unlikely(!blkg)) |
203 | goto err_put; | |
cd1604fa TH |
204 | |
205 | /* insert */ | |
a637120e TH |
206 | ret = radix_tree_preload(GFP_ATOMIC); |
207 | if (ret) | |
208 | goto err_free; | |
209 | ||
cd1604fa | 210 | spin_lock(&blkcg->lock); |
a637120e TH |
211 | ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg); |
212 | if (likely(!ret)) { | |
213 | hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); | |
214 | list_add(&blkg->q_node, &q->blkg_list); | |
215 | } | |
cd1604fa | 216 | spin_unlock(&blkcg->lock); |
496fb780 | 217 | |
a637120e TH |
218 | radix_tree_preload_end(); |
219 | ||
220 | if (!ret) | |
221 | return blkg; | |
222 | err_free: | |
223 | blkg_free(blkg); | |
496fb780 TH |
224 | err_put: |
225 | css_put(&blkcg->css); | |
226 | return ERR_PTR(ret); | |
31e4c28d | 227 | } |
3c96cb32 | 228 | |
3c798398 TH |
229 | struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, |
230 | struct request_queue *q) | |
3c96cb32 TH |
231 | { |
232 | /* | |
233 | * This could be the first entry point of blkcg implementation and | |
234 | * we shouldn't allow anything to go through for a bypassing queue. | |
235 | */ | |
236 | if (unlikely(blk_queue_bypass(q))) | |
237 | return ERR_PTR(blk_queue_dead(q) ? -EINVAL : -EBUSY); | |
238 | return __blkg_lookup_create(blkcg, q); | |
239 | } | |
cd1604fa | 240 | EXPORT_SYMBOL_GPL(blkg_lookup_create); |
31e4c28d | 241 | |
3c798398 | 242 | static void blkg_destroy(struct blkcg_gq *blkg) |
03aa264a | 243 | { |
3c798398 | 244 | struct blkcg *blkcg = blkg->blkcg; |
03aa264a | 245 | |
27e1f9d1 | 246 | lockdep_assert_held(blkg->q->queue_lock); |
9f13ef67 | 247 | lockdep_assert_held(&blkcg->lock); |
03aa264a TH |
248 | |
249 | /* Something wrong if we are trying to remove same group twice */ | |
e8989fae | 250 | WARN_ON_ONCE(list_empty(&blkg->q_node)); |
9f13ef67 | 251 | WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node)); |
a637120e TH |
252 | |
253 | radix_tree_delete(&blkcg->blkg_tree, blkg->q->id); | |
e8989fae | 254 | list_del_init(&blkg->q_node); |
9f13ef67 | 255 | hlist_del_init_rcu(&blkg->blkcg_node); |
03aa264a | 256 | |
a637120e TH |
257 | /* |
258 | * Both setting lookup hint to and clearing it from @blkg are done | |
259 | * under queue_lock. If it's not pointing to @blkg now, it never | |
260 | * will. Hint assignment itself can race safely. | |
261 | */ | |
262 | if (rcu_dereference_raw(blkcg->blkg_hint) == blkg) | |
263 | rcu_assign_pointer(blkcg->blkg_hint, NULL); | |
264 | ||
03aa264a TH |
265 | /* |
266 | * Put the reference taken at the time of creation so that when all | |
267 | * queues are gone, group can be destroyed. | |
268 | */ | |
269 | blkg_put(blkg); | |
270 | } | |
271 | ||
9f13ef67 TH |
272 | /** |
273 | * blkg_destroy_all - destroy all blkgs associated with a request_queue | |
274 | * @q: request_queue of interest | |
9f13ef67 | 275 | * |
3c96cb32 | 276 | * Destroy all blkgs associated with @q. |
9f13ef67 | 277 | */ |
3c96cb32 | 278 | static void blkg_destroy_all(struct request_queue *q) |
72e06c25 | 279 | { |
3c798398 | 280 | struct blkcg_gq *blkg, *n; |
72e06c25 | 281 | |
6d18b008 | 282 | lockdep_assert_held(q->queue_lock); |
72e06c25 | 283 | |
9f13ef67 | 284 | list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { |
3c798398 | 285 | struct blkcg *blkcg = blkg->blkcg; |
72e06c25 | 286 | |
9f13ef67 TH |
287 | spin_lock(&blkcg->lock); |
288 | blkg_destroy(blkg); | |
289 | spin_unlock(&blkcg->lock); | |
72e06c25 TH |
290 | } |
291 | } | |
292 | ||
1adaf3dd TH |
293 | static void blkg_rcu_free(struct rcu_head *rcu_head) |
294 | { | |
3c798398 | 295 | blkg_free(container_of(rcu_head, struct blkcg_gq, rcu_head)); |
1adaf3dd TH |
296 | } |
297 | ||
3c798398 | 298 | void __blkg_release(struct blkcg_gq *blkg) |
1adaf3dd TH |
299 | { |
300 | /* release the extra blkcg reference this blkg has been holding */ | |
301 | css_put(&blkg->blkcg->css); | |
302 | ||
303 | /* | |
304 | * A group is freed in rcu manner. But having an rcu lock does not | |
305 | * mean that one can access all the fields of blkg and assume these | |
306 | * are valid. For example, don't try to follow throtl_data and | |
307 | * request queue links. | |
308 | * | |
309 | * Having a reference to blkg under an rcu allows acess to only | |
310 | * values local to groups like group stats and group rate limits | |
311 | */ | |
312 | call_rcu(&blkg->rcu_head, blkg_rcu_free); | |
313 | } | |
314 | EXPORT_SYMBOL_GPL(__blkg_release); | |
315 | ||
3c798398 TH |
316 | static int blkcg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, |
317 | u64 val) | |
303a3acb | 318 | { |
3c798398 TH |
319 | struct blkcg *blkcg = cgroup_to_blkcg(cgroup); |
320 | struct blkcg_gq *blkg; | |
303a3acb | 321 | struct hlist_node *n; |
bc0d6501 | 322 | int i; |
303a3acb | 323 | |
bc0d6501 | 324 | mutex_lock(&blkcg_pol_mutex); |
303a3acb | 325 | spin_lock_irq(&blkcg->lock); |
997a026c TH |
326 | |
327 | /* | |
328 | * Note that stat reset is racy - it doesn't synchronize against | |
329 | * stat updates. This is a debug feature which shouldn't exist | |
330 | * anyway. If you get hit by a race, retry. | |
331 | */ | |
303a3acb | 332 | hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) { |
8bd435b3 | 333 | for (i = 0; i < BLKCG_MAX_POLS; i++) { |
3c798398 | 334 | struct blkcg_policy *pol = blkcg_policy[i]; |
549d3aa8 | 335 | |
a2b1693b | 336 | if (blkcg_policy_enabled(blkg->q, pol) && |
f9fcc2d3 TH |
337 | pol->pd_reset_stats_fn) |
338 | pol->pd_reset_stats_fn(blkg); | |
bc0d6501 | 339 | } |
303a3acb | 340 | } |
f0bdc8cd | 341 | |
303a3acb | 342 | spin_unlock_irq(&blkcg->lock); |
bc0d6501 | 343 | mutex_unlock(&blkcg_pol_mutex); |
303a3acb DS |
344 | return 0; |
345 | } | |
346 | ||
3c798398 | 347 | static const char *blkg_dev_name(struct blkcg_gq *blkg) |
303a3acb | 348 | { |
d3d32e69 TH |
349 | /* some drivers (floppy) instantiate a queue w/o disk registered */ |
350 | if (blkg->q->backing_dev_info.dev) | |
351 | return dev_name(blkg->q->backing_dev_info.dev); | |
352 | return NULL; | |
303a3acb DS |
353 | } |
354 | ||
d3d32e69 TH |
355 | /** |
356 | * blkcg_print_blkgs - helper for printing per-blkg data | |
357 | * @sf: seq_file to print to | |
358 | * @blkcg: blkcg of interest | |
359 | * @prfill: fill function to print out a blkg | |
360 | * @pol: policy in question | |
361 | * @data: data to be passed to @prfill | |
362 | * @show_total: to print out sum of prfill return values or not | |
363 | * | |
364 | * This function invokes @prfill on each blkg of @blkcg if pd for the | |
365 | * policy specified by @pol exists. @prfill is invoked with @sf, the | |
366 | * policy data and @data. If @show_total is %true, the sum of the return | |
367 | * values from @prfill is printed with "Total" label at the end. | |
368 | * | |
369 | * This is to be used to construct print functions for | |
370 | * cftype->read_seq_string method. | |
371 | */ | |
3c798398 | 372 | void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg, |
f95a04af TH |
373 | u64 (*prfill)(struct seq_file *, |
374 | struct blkg_policy_data *, int), | |
3c798398 | 375 | const struct blkcg_policy *pol, int data, |
ec399347 | 376 | bool show_total) |
5624a4e4 | 377 | { |
3c798398 | 378 | struct blkcg_gq *blkg; |
d3d32e69 TH |
379 | struct hlist_node *n; |
380 | u64 total = 0; | |
5624a4e4 | 381 | |
d3d32e69 TH |
382 | spin_lock_irq(&blkcg->lock); |
383 | hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) | |
a2b1693b | 384 | if (blkcg_policy_enabled(blkg->q, pol)) |
f95a04af | 385 | total += prfill(sf, blkg->pd[pol->plid], data); |
d3d32e69 TH |
386 | spin_unlock_irq(&blkcg->lock); |
387 | ||
388 | if (show_total) | |
389 | seq_printf(sf, "Total %llu\n", (unsigned long long)total); | |
390 | } | |
829fdb50 | 391 | EXPORT_SYMBOL_GPL(blkcg_print_blkgs); |
d3d32e69 TH |
392 | |
393 | /** | |
394 | * __blkg_prfill_u64 - prfill helper for a single u64 value | |
395 | * @sf: seq_file to print to | |
f95a04af | 396 | * @pd: policy private data of interest |
d3d32e69 TH |
397 | * @v: value to print |
398 | * | |
f95a04af | 399 | * Print @v to @sf for the device assocaited with @pd. |
d3d32e69 | 400 | */ |
f95a04af | 401 | u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v) |
d3d32e69 | 402 | { |
f95a04af | 403 | const char *dname = blkg_dev_name(pd->blkg); |
d3d32e69 TH |
404 | |
405 | if (!dname) | |
406 | return 0; | |
407 | ||
408 | seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v); | |
409 | return v; | |
410 | } | |
829fdb50 | 411 | EXPORT_SYMBOL_GPL(__blkg_prfill_u64); |
d3d32e69 TH |
412 | |
413 | /** | |
414 | * __blkg_prfill_rwstat - prfill helper for a blkg_rwstat | |
415 | * @sf: seq_file to print to | |
f95a04af | 416 | * @pd: policy private data of interest |
d3d32e69 TH |
417 | * @rwstat: rwstat to print |
418 | * | |
f95a04af | 419 | * Print @rwstat to @sf for the device assocaited with @pd. |
d3d32e69 | 420 | */ |
f95a04af | 421 | u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, |
829fdb50 | 422 | const struct blkg_rwstat *rwstat) |
d3d32e69 TH |
423 | { |
424 | static const char *rwstr[] = { | |
425 | [BLKG_RWSTAT_READ] = "Read", | |
426 | [BLKG_RWSTAT_WRITE] = "Write", | |
427 | [BLKG_RWSTAT_SYNC] = "Sync", | |
428 | [BLKG_RWSTAT_ASYNC] = "Async", | |
429 | }; | |
f95a04af | 430 | const char *dname = blkg_dev_name(pd->blkg); |
d3d32e69 TH |
431 | u64 v; |
432 | int i; | |
433 | ||
434 | if (!dname) | |
435 | return 0; | |
436 | ||
437 | for (i = 0; i < BLKG_RWSTAT_NR; i++) | |
438 | seq_printf(sf, "%s %s %llu\n", dname, rwstr[i], | |
439 | (unsigned long long)rwstat->cnt[i]); | |
440 | ||
441 | v = rwstat->cnt[BLKG_RWSTAT_READ] + rwstat->cnt[BLKG_RWSTAT_WRITE]; | |
442 | seq_printf(sf, "%s Total %llu\n", dname, (unsigned long long)v); | |
443 | return v; | |
444 | } | |
445 | ||
5bc4afb1 TH |
446 | /** |
447 | * blkg_prfill_stat - prfill callback for blkg_stat | |
448 | * @sf: seq_file to print to | |
f95a04af TH |
449 | * @pd: policy private data of interest |
450 | * @off: offset to the blkg_stat in @pd | |
5bc4afb1 TH |
451 | * |
452 | * prfill callback for printing a blkg_stat. | |
453 | */ | |
f95a04af | 454 | u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off) |
d3d32e69 | 455 | { |
f95a04af | 456 | return __blkg_prfill_u64(sf, pd, blkg_stat_read((void *)pd + off)); |
d3d32e69 | 457 | } |
5bc4afb1 | 458 | EXPORT_SYMBOL_GPL(blkg_prfill_stat); |
d3d32e69 | 459 | |
5bc4afb1 TH |
460 | /** |
461 | * blkg_prfill_rwstat - prfill callback for blkg_rwstat | |
462 | * @sf: seq_file to print to | |
f95a04af TH |
463 | * @pd: policy private data of interest |
464 | * @off: offset to the blkg_rwstat in @pd | |
5bc4afb1 TH |
465 | * |
466 | * prfill callback for printing a blkg_rwstat. | |
467 | */ | |
f95a04af TH |
468 | u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, |
469 | int off) | |
d3d32e69 | 470 | { |
f95a04af | 471 | struct blkg_rwstat rwstat = blkg_rwstat_read((void *)pd + off); |
d3d32e69 | 472 | |
f95a04af | 473 | return __blkg_prfill_rwstat(sf, pd, &rwstat); |
d3d32e69 | 474 | } |
5bc4afb1 | 475 | EXPORT_SYMBOL_GPL(blkg_prfill_rwstat); |
d3d32e69 | 476 | |
3a8b31d3 TH |
477 | /** |
478 | * blkg_conf_prep - parse and prepare for per-blkg config update | |
479 | * @blkcg: target block cgroup | |
da8b0662 | 480 | * @pol: target policy |
3a8b31d3 TH |
481 | * @input: input string |
482 | * @ctx: blkg_conf_ctx to be filled | |
483 | * | |
484 | * Parse per-blkg config update from @input and initialize @ctx with the | |
485 | * result. @ctx->blkg points to the blkg to be updated and @ctx->v the new | |
da8b0662 TH |
486 | * value. This function returns with RCU read lock and queue lock held and |
487 | * must be paired with blkg_conf_finish(). | |
3a8b31d3 | 488 | */ |
3c798398 TH |
489 | int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, |
490 | const char *input, struct blkg_conf_ctx *ctx) | |
da8b0662 | 491 | __acquires(rcu) __acquires(disk->queue->queue_lock) |
34d0f179 | 492 | { |
3a8b31d3 | 493 | struct gendisk *disk; |
3c798398 | 494 | struct blkcg_gq *blkg; |
726fa694 TH |
495 | unsigned int major, minor; |
496 | unsigned long long v; | |
497 | int part, ret; | |
34d0f179 | 498 | |
726fa694 TH |
499 | if (sscanf(input, "%u:%u %llu", &major, &minor, &v) != 3) |
500 | return -EINVAL; | |
3a8b31d3 | 501 | |
726fa694 | 502 | disk = get_gendisk(MKDEV(major, minor), &part); |
4bfd482e | 503 | if (!disk || part) |
726fa694 | 504 | return -EINVAL; |
e56da7e2 TH |
505 | |
506 | rcu_read_lock(); | |
4bfd482e | 507 | spin_lock_irq(disk->queue->queue_lock); |
da8b0662 | 508 | |
a2b1693b | 509 | if (blkcg_policy_enabled(disk->queue, pol)) |
3c96cb32 | 510 | blkg = blkg_lookup_create(blkcg, disk->queue); |
a2b1693b TH |
511 | else |
512 | blkg = ERR_PTR(-EINVAL); | |
e56da7e2 | 513 | |
4bfd482e TH |
514 | if (IS_ERR(blkg)) { |
515 | ret = PTR_ERR(blkg); | |
3a8b31d3 | 516 | rcu_read_unlock(); |
da8b0662 | 517 | spin_unlock_irq(disk->queue->queue_lock); |
3a8b31d3 TH |
518 | put_disk(disk); |
519 | /* | |
520 | * If queue was bypassing, we should retry. Do so after a | |
521 | * short msleep(). It isn't strictly necessary but queue | |
522 | * can be bypassing for some time and it's always nice to | |
523 | * avoid busy looping. | |
524 | */ | |
525 | if (ret == -EBUSY) { | |
526 | msleep(10); | |
527 | ret = restart_syscall(); | |
7702e8f4 | 528 | } |
726fa694 | 529 | return ret; |
062a644d | 530 | } |
3a8b31d3 TH |
531 | |
532 | ctx->disk = disk; | |
533 | ctx->blkg = blkg; | |
726fa694 TH |
534 | ctx->v = v; |
535 | return 0; | |
34d0f179 | 536 | } |
829fdb50 | 537 | EXPORT_SYMBOL_GPL(blkg_conf_prep); |
34d0f179 | 538 | |
3a8b31d3 TH |
539 | /** |
540 | * blkg_conf_finish - finish up per-blkg config update | |
541 | * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep() | |
542 | * | |
543 | * Finish up after per-blkg config update. This function must be paired | |
544 | * with blkg_conf_prep(). | |
545 | */ | |
829fdb50 | 546 | void blkg_conf_finish(struct blkg_conf_ctx *ctx) |
da8b0662 | 547 | __releases(ctx->disk->queue->queue_lock) __releases(rcu) |
34d0f179 | 548 | { |
da8b0662 | 549 | spin_unlock_irq(ctx->disk->queue->queue_lock); |
3a8b31d3 TH |
550 | rcu_read_unlock(); |
551 | put_disk(ctx->disk); | |
34d0f179 | 552 | } |
829fdb50 | 553 | EXPORT_SYMBOL_GPL(blkg_conf_finish); |
34d0f179 | 554 | |
3c798398 | 555 | struct cftype blkcg_files[] = { |
84c124da DS |
556 | { |
557 | .name = "reset_stats", | |
3c798398 | 558 | .write_u64 = blkcg_reset_stats, |
22084190 | 559 | }, |
4baf6e33 | 560 | { } /* terminate */ |
31e4c28d VG |
561 | }; |
562 | ||
9f13ef67 | 563 | /** |
3c798398 | 564 | * blkcg_pre_destroy - cgroup pre_destroy callback |
9f13ef67 TH |
565 | * @cgroup: cgroup of interest |
566 | * | |
567 | * This function is called when @cgroup is about to go away and responsible | |
568 | * for shooting down all blkgs associated with @cgroup. blkgs should be | |
569 | * removed while holding both q and blkcg locks. As blkcg lock is nested | |
570 | * inside q lock, this function performs reverse double lock dancing. | |
571 | * | |
572 | * This is the blkcg counterpart of ioc_release_fn(). | |
573 | */ | |
3c798398 | 574 | static int blkcg_pre_destroy(struct cgroup *cgroup) |
31e4c28d | 575 | { |
3c798398 | 576 | struct blkcg *blkcg = cgroup_to_blkcg(cgroup); |
b1c35769 | 577 | |
9f13ef67 | 578 | spin_lock_irq(&blkcg->lock); |
7ee9c562 | 579 | |
9f13ef67 | 580 | while (!hlist_empty(&blkcg->blkg_list)) { |
3c798398 TH |
581 | struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first, |
582 | struct blkcg_gq, blkcg_node); | |
c875f4d0 | 583 | struct request_queue *q = blkg->q; |
b1c35769 | 584 | |
9f13ef67 TH |
585 | if (spin_trylock(q->queue_lock)) { |
586 | blkg_destroy(blkg); | |
587 | spin_unlock(q->queue_lock); | |
588 | } else { | |
589 | spin_unlock_irq(&blkcg->lock); | |
9f13ef67 | 590 | cpu_relax(); |
a5567932 | 591 | spin_lock_irq(&blkcg->lock); |
0f3942a3 | 592 | } |
9f13ef67 | 593 | } |
b1c35769 | 594 | |
9f13ef67 | 595 | spin_unlock_irq(&blkcg->lock); |
7ee9c562 TH |
596 | return 0; |
597 | } | |
598 | ||
3c798398 | 599 | static void blkcg_destroy(struct cgroup *cgroup) |
7ee9c562 | 600 | { |
3c798398 | 601 | struct blkcg *blkcg = cgroup_to_blkcg(cgroup); |
7ee9c562 | 602 | |
3c798398 | 603 | if (blkcg != &blkcg_root) |
67523c48 | 604 | kfree(blkcg); |
31e4c28d VG |
605 | } |
606 | ||
3c798398 | 607 | static struct cgroup_subsys_state *blkcg_create(struct cgroup *cgroup) |
31e4c28d | 608 | { |
9a9e8a26 | 609 | static atomic64_t id_seq = ATOMIC64_INIT(0); |
3c798398 | 610 | struct blkcg *blkcg; |
0341509f | 611 | struct cgroup *parent = cgroup->parent; |
31e4c28d | 612 | |
0341509f | 613 | if (!parent) { |
3c798398 | 614 | blkcg = &blkcg_root; |
31e4c28d VG |
615 | goto done; |
616 | } | |
617 | ||
31e4c28d VG |
618 | blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); |
619 | if (!blkcg) | |
620 | return ERR_PTR(-ENOMEM); | |
621 | ||
3381cb8d | 622 | blkcg->cfq_weight = CFQ_WEIGHT_DEFAULT; |
9a9e8a26 | 623 | blkcg->id = atomic64_inc_return(&id_seq); /* root is 0, start from 1 */ |
31e4c28d VG |
624 | done: |
625 | spin_lock_init(&blkcg->lock); | |
a637120e | 626 | INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_ATOMIC); |
31e4c28d VG |
627 | INIT_HLIST_HEAD(&blkcg->blkg_list); |
628 | ||
629 | return &blkcg->css; | |
630 | } | |
631 | ||
5efd6113 TH |
632 | /** |
633 | * blkcg_init_queue - initialize blkcg part of request queue | |
634 | * @q: request_queue to initialize | |
635 | * | |
636 | * Called from blk_alloc_queue_node(). Responsible for initializing blkcg | |
637 | * part of new request_queue @q. | |
638 | * | |
639 | * RETURNS: | |
640 | * 0 on success, -errno on failure. | |
641 | */ | |
642 | int blkcg_init_queue(struct request_queue *q) | |
643 | { | |
644 | might_sleep(); | |
645 | ||
3c96cb32 | 646 | return blk_throtl_init(q); |
5efd6113 TH |
647 | } |
648 | ||
649 | /** | |
650 | * blkcg_drain_queue - drain blkcg part of request_queue | |
651 | * @q: request_queue to drain | |
652 | * | |
653 | * Called from blk_drain_queue(). Responsible for draining blkcg part. | |
654 | */ | |
655 | void blkcg_drain_queue(struct request_queue *q) | |
656 | { | |
657 | lockdep_assert_held(q->queue_lock); | |
658 | ||
659 | blk_throtl_drain(q); | |
660 | } | |
661 | ||
662 | /** | |
663 | * blkcg_exit_queue - exit and release blkcg part of request_queue | |
664 | * @q: request_queue being released | |
665 | * | |
666 | * Called from blk_release_queue(). Responsible for exiting blkcg part. | |
667 | */ | |
668 | void blkcg_exit_queue(struct request_queue *q) | |
669 | { | |
6d18b008 | 670 | spin_lock_irq(q->queue_lock); |
3c96cb32 | 671 | blkg_destroy_all(q); |
6d18b008 TH |
672 | spin_unlock_irq(q->queue_lock); |
673 | ||
5efd6113 TH |
674 | blk_throtl_exit(q); |
675 | } | |
676 | ||
31e4c28d VG |
677 | /* |
678 | * We cannot support shared io contexts, as we have no mean to support | |
679 | * two tasks with the same ioc in two different groups without major rework | |
680 | * of the main cic data structures. For now we allow a task to change | |
681 | * its cgroup only if it's the only owner of its ioc. | |
682 | */ | |
3c798398 | 683 | static int blkcg_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset) |
31e4c28d | 684 | { |
bb9d97b6 | 685 | struct task_struct *task; |
31e4c28d VG |
686 | struct io_context *ioc; |
687 | int ret = 0; | |
688 | ||
689 | /* task_lock() is needed to avoid races with exit_io_context() */ | |
bb9d97b6 TH |
690 | cgroup_taskset_for_each(task, cgrp, tset) { |
691 | task_lock(task); | |
692 | ioc = task->io_context; | |
693 | if (ioc && atomic_read(&ioc->nr_tasks) > 1) | |
694 | ret = -EINVAL; | |
695 | task_unlock(task); | |
696 | if (ret) | |
697 | break; | |
698 | } | |
31e4c28d VG |
699 | return ret; |
700 | } | |
701 | ||
676f7c8f TH |
702 | struct cgroup_subsys blkio_subsys = { |
703 | .name = "blkio", | |
3c798398 TH |
704 | .create = blkcg_create, |
705 | .can_attach = blkcg_can_attach, | |
706 | .pre_destroy = blkcg_pre_destroy, | |
707 | .destroy = blkcg_destroy, | |
676f7c8f | 708 | .subsys_id = blkio_subsys_id, |
3c798398 | 709 | .base_cftypes = blkcg_files, |
676f7c8f TH |
710 | .module = THIS_MODULE, |
711 | }; | |
712 | EXPORT_SYMBOL_GPL(blkio_subsys); | |
713 | ||
a2b1693b TH |
714 | /** |
715 | * blkcg_activate_policy - activate a blkcg policy on a request_queue | |
716 | * @q: request_queue of interest | |
717 | * @pol: blkcg policy to activate | |
718 | * | |
719 | * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through | |
720 | * bypass mode to populate its blkgs with policy_data for @pol. | |
721 | * | |
722 | * Activation happens with @q bypassed, so nobody would be accessing blkgs | |
723 | * from IO path. Update of each blkg is protected by both queue and blkcg | |
724 | * locks so that holding either lock and testing blkcg_policy_enabled() is | |
725 | * always enough for dereferencing policy data. | |
726 | * | |
727 | * The caller is responsible for synchronizing [de]activations and policy | |
728 | * [un]registerations. Returns 0 on success, -errno on failure. | |
729 | */ | |
730 | int blkcg_activate_policy(struct request_queue *q, | |
3c798398 | 731 | const struct blkcg_policy *pol) |
a2b1693b TH |
732 | { |
733 | LIST_HEAD(pds); | |
3c798398 | 734 | struct blkcg_gq *blkg; |
a2b1693b TH |
735 | struct blkg_policy_data *pd, *n; |
736 | int cnt = 0, ret; | |
737 | ||
738 | if (blkcg_policy_enabled(q, pol)) | |
739 | return 0; | |
740 | ||
741 | blk_queue_bypass_start(q); | |
742 | ||
743 | /* make sure the root blkg exists and count the existing blkgs */ | |
744 | spin_lock_irq(q->queue_lock); | |
745 | ||
746 | rcu_read_lock(); | |
3c798398 | 747 | blkg = __blkg_lookup_create(&blkcg_root, q); |
a2b1693b TH |
748 | rcu_read_unlock(); |
749 | ||
750 | if (IS_ERR(blkg)) { | |
751 | ret = PTR_ERR(blkg); | |
752 | goto out_unlock; | |
753 | } | |
754 | q->root_blkg = blkg; | |
755 | ||
756 | list_for_each_entry(blkg, &q->blkg_list, q_node) | |
757 | cnt++; | |
758 | ||
759 | spin_unlock_irq(q->queue_lock); | |
760 | ||
761 | /* allocate policy_data for all existing blkgs */ | |
762 | while (cnt--) { | |
f95a04af | 763 | pd = kzalloc_node(pol->pd_size, GFP_KERNEL, q->node); |
a2b1693b TH |
764 | if (!pd) { |
765 | ret = -ENOMEM; | |
766 | goto out_free; | |
767 | } | |
768 | list_add_tail(&pd->alloc_node, &pds); | |
769 | } | |
770 | ||
771 | /* | |
772 | * Install the allocated pds. With @q bypassing, no new blkg | |
773 | * should have been created while the queue lock was dropped. | |
774 | */ | |
775 | spin_lock_irq(q->queue_lock); | |
776 | ||
777 | list_for_each_entry(blkg, &q->blkg_list, q_node) { | |
778 | if (WARN_ON(list_empty(&pds))) { | |
779 | /* umm... this shouldn't happen, just abort */ | |
780 | ret = -ENOMEM; | |
781 | goto out_unlock; | |
782 | } | |
783 | pd = list_first_entry(&pds, struct blkg_policy_data, alloc_node); | |
784 | list_del_init(&pd->alloc_node); | |
785 | ||
786 | /* grab blkcg lock too while installing @pd on @blkg */ | |
787 | spin_lock(&blkg->blkcg->lock); | |
788 | ||
789 | blkg->pd[pol->plid] = pd; | |
790 | pd->blkg = blkg; | |
f9fcc2d3 | 791 | pol->pd_init_fn(blkg); |
a2b1693b TH |
792 | |
793 | spin_unlock(&blkg->blkcg->lock); | |
794 | } | |
795 | ||
796 | __set_bit(pol->plid, q->blkcg_pols); | |
797 | ret = 0; | |
798 | out_unlock: | |
799 | spin_unlock_irq(q->queue_lock); | |
800 | out_free: | |
801 | blk_queue_bypass_end(q); | |
802 | list_for_each_entry_safe(pd, n, &pds, alloc_node) | |
803 | kfree(pd); | |
804 | return ret; | |
805 | } | |
806 | EXPORT_SYMBOL_GPL(blkcg_activate_policy); | |
807 | ||
808 | /** | |
809 | * blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue | |
810 | * @q: request_queue of interest | |
811 | * @pol: blkcg policy to deactivate | |
812 | * | |
813 | * Deactivate @pol on @q. Follows the same synchronization rules as | |
814 | * blkcg_activate_policy(). | |
815 | */ | |
816 | void blkcg_deactivate_policy(struct request_queue *q, | |
3c798398 | 817 | const struct blkcg_policy *pol) |
a2b1693b | 818 | { |
3c798398 | 819 | struct blkcg_gq *blkg; |
a2b1693b TH |
820 | |
821 | if (!blkcg_policy_enabled(q, pol)) | |
822 | return; | |
823 | ||
824 | blk_queue_bypass_start(q); | |
825 | spin_lock_irq(q->queue_lock); | |
826 | ||
827 | __clear_bit(pol->plid, q->blkcg_pols); | |
828 | ||
6d18b008 TH |
829 | /* if no policy is left, no need for blkgs - shoot them down */ |
830 | if (bitmap_empty(q->blkcg_pols, BLKCG_MAX_POLS)) | |
831 | blkg_destroy_all(q); | |
832 | ||
a2b1693b TH |
833 | list_for_each_entry(blkg, &q->blkg_list, q_node) { |
834 | /* grab blkcg lock too while removing @pd from @blkg */ | |
835 | spin_lock(&blkg->blkcg->lock); | |
836 | ||
f9fcc2d3 TH |
837 | if (pol->pd_exit_fn) |
838 | pol->pd_exit_fn(blkg); | |
a2b1693b TH |
839 | |
840 | kfree(blkg->pd[pol->plid]); | |
841 | blkg->pd[pol->plid] = NULL; | |
842 | ||
843 | spin_unlock(&blkg->blkcg->lock); | |
844 | } | |
845 | ||
846 | spin_unlock_irq(q->queue_lock); | |
847 | blk_queue_bypass_end(q); | |
848 | } | |
849 | EXPORT_SYMBOL_GPL(blkcg_deactivate_policy); | |
850 | ||
8bd435b3 | 851 | /** |
3c798398 TH |
852 | * blkcg_policy_register - register a blkcg policy |
853 | * @pol: blkcg policy to register | |
8bd435b3 | 854 | * |
3c798398 TH |
855 | * Register @pol with blkcg core. Might sleep and @pol may be modified on |
856 | * successful registration. Returns 0 on success and -errno on failure. | |
8bd435b3 | 857 | */ |
3c798398 | 858 | int blkcg_policy_register(struct blkcg_policy *pol) |
3e252066 | 859 | { |
8bd435b3 | 860 | int i, ret; |
e8989fae | 861 | |
f95a04af TH |
862 | if (WARN_ON(pol->pd_size < sizeof(struct blkg_policy_data))) |
863 | return -EINVAL; | |
864 | ||
bc0d6501 TH |
865 | mutex_lock(&blkcg_pol_mutex); |
866 | ||
8bd435b3 TH |
867 | /* find an empty slot */ |
868 | ret = -ENOSPC; | |
869 | for (i = 0; i < BLKCG_MAX_POLS; i++) | |
3c798398 | 870 | if (!blkcg_policy[i]) |
8bd435b3 TH |
871 | break; |
872 | if (i >= BLKCG_MAX_POLS) | |
873 | goto out_unlock; | |
035d10b2 | 874 | |
8bd435b3 | 875 | /* register and update blkgs */ |
3c798398 TH |
876 | pol->plid = i; |
877 | blkcg_policy[i] = pol; | |
8bd435b3 | 878 | |
8bd435b3 | 879 | /* everything is in place, add intf files for the new policy */ |
3c798398 TH |
880 | if (pol->cftypes) |
881 | WARN_ON(cgroup_add_cftypes(&blkio_subsys, pol->cftypes)); | |
8bd435b3 TH |
882 | ret = 0; |
883 | out_unlock: | |
bc0d6501 | 884 | mutex_unlock(&blkcg_pol_mutex); |
8bd435b3 | 885 | return ret; |
3e252066 | 886 | } |
3c798398 | 887 | EXPORT_SYMBOL_GPL(blkcg_policy_register); |
3e252066 | 888 | |
8bd435b3 | 889 | /** |
3c798398 TH |
890 | * blkcg_policy_unregister - unregister a blkcg policy |
891 | * @pol: blkcg policy to unregister | |
8bd435b3 | 892 | * |
3c798398 | 893 | * Undo blkcg_policy_register(@pol). Might sleep. |
8bd435b3 | 894 | */ |
3c798398 | 895 | void blkcg_policy_unregister(struct blkcg_policy *pol) |
3e252066 | 896 | { |
bc0d6501 TH |
897 | mutex_lock(&blkcg_pol_mutex); |
898 | ||
3c798398 | 899 | if (WARN_ON(blkcg_policy[pol->plid] != pol)) |
8bd435b3 TH |
900 | goto out_unlock; |
901 | ||
902 | /* kill the intf files first */ | |
3c798398 TH |
903 | if (pol->cftypes) |
904 | cgroup_rm_cftypes(&blkio_subsys, pol->cftypes); | |
44ea53de | 905 | |
8bd435b3 | 906 | /* unregister and update blkgs */ |
3c798398 | 907 | blkcg_policy[pol->plid] = NULL; |
8bd435b3 | 908 | out_unlock: |
bc0d6501 | 909 | mutex_unlock(&blkcg_pol_mutex); |
3e252066 | 910 | } |
3c798398 | 911 | EXPORT_SYMBOL_GPL(blkcg_policy_unregister); |