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V4L/DVB: drivers/media: Eliminate a NULL pointer dereference
[linux/fpc-iii.git] / block / blk-cgroup.c
bloba6809645d212d9cf970b85473e3d9c05bc4ba652
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>
14 #include <linux/seq_file.h>
15 #include <linux/kdev_t.h>
16 #include <linux/module.h>
17 #include <linux/err.h>
18 #include <linux/blkdev.h>
19 #include <linux/slab.h>
20 #include "blk-cgroup.h"
21 #include <linux/genhd.h>
22
23 #define MAX_KEY_LEN 100
24
25 static DEFINE_SPINLOCK(blkio_list_lock);
26 static LIST_HEAD(blkio_list);
27
28 struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
29 EXPORT_SYMBOL_GPL(blkio_root_cgroup);
30
31 static struct cgroup_subsys_state *blkiocg_create(struct cgroup_subsys *,
32 struct cgroup *);
33 static int blkiocg_can_attach(struct cgroup_subsys *, struct cgroup *,
34 struct task_struct *, bool);
35 static void blkiocg_attach(struct cgroup_subsys *, struct cgroup *,
36 struct cgroup *, struct task_struct *, bool);
37 static void blkiocg_destroy(struct cgroup_subsys *, struct cgroup *);
38 static int blkiocg_populate(struct cgroup_subsys *, struct cgroup *);
39
40 struct cgroup_subsys blkio_subsys = {
41 .name = "blkio",
42 .create = blkiocg_create,
43 .can_attach = blkiocg_can_attach,
44 .attach = blkiocg_attach,
45 .destroy = blkiocg_destroy,
46 .populate = blkiocg_populate,
47 #ifdef CONFIG_BLK_CGROUP
48 /* note: blkio_subsys_id is otherwise defined in blk-cgroup.h */
49 .subsys_id = blkio_subsys_id,
50 #endif
51 .use_id = 1,
52 .module = THIS_MODULE,
53 };
54 EXPORT_SYMBOL_GPL(blkio_subsys);
55
56 static inline void blkio_policy_insert_node(struct blkio_cgroup *blkcg,
57 struct blkio_policy_node *pn)
58 {
59 list_add(&pn->node, &blkcg->policy_list);
60 }
61
62 /* Must be called with blkcg->lock held */
63 static inline void blkio_policy_delete_node(struct blkio_policy_node *pn)
64 {
65 list_del(&pn->node);
66 }
67
68 /* Must be called with blkcg->lock held */
69 static struct blkio_policy_node *
70 blkio_policy_search_node(const struct blkio_cgroup *blkcg, dev_t dev)
71 {
72 struct blkio_policy_node *pn;
73
74 list_for_each_entry(pn, &blkcg->policy_list, node) {
75 if (pn->dev == dev)
76 return pn;
77 }
78
79 return NULL;
80 }
81
82 struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
83 {
84 return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
85 struct blkio_cgroup, css);
86 }
87 EXPORT_SYMBOL_GPL(cgroup_to_blkio_cgroup);
88
89 /*
90 * Add to the appropriate stat variable depending on the request type.
91 * This should be called with the blkg->stats_lock held.
92 */
93 static void blkio_add_stat(uint64_t *stat, uint64_t add, bool direction,
94 bool sync)
95 {
96 if (direction)
97 stat[BLKIO_STAT_WRITE] += add;
98 else
99 stat[BLKIO_STAT_READ] += add;
100 if (sync)
101 stat[BLKIO_STAT_SYNC] += add;
102 else
103 stat[BLKIO_STAT_ASYNC] += add;
104 }
105
106 /*
107 * Decrements the appropriate stat variable if non-zero depending on the
108 * request type. Panics on value being zero.
109 * This should be called with the blkg->stats_lock held.
110 */
111 static void blkio_check_and_dec_stat(uint64_t *stat, bool direction, bool sync)
112 {
113 if (direction) {
114 BUG_ON(stat[BLKIO_STAT_WRITE] == 0);
115 stat[BLKIO_STAT_WRITE]--;
116 } else {
117 BUG_ON(stat[BLKIO_STAT_READ] == 0);
118 stat[BLKIO_STAT_READ]--;
119 }
120 if (sync) {
121 BUG_ON(stat[BLKIO_STAT_SYNC] == 0);
122 stat[BLKIO_STAT_SYNC]--;
123 } else {
124 BUG_ON(stat[BLKIO_STAT_ASYNC] == 0);
125 stat[BLKIO_STAT_ASYNC]--;
126 }
127 }
128
129 #ifdef CONFIG_DEBUG_BLK_CGROUP
130 /* This should be called with the blkg->stats_lock held. */
131 static void blkio_set_start_group_wait_time(struct blkio_group *blkg,
132 struct blkio_group *curr_blkg)
133 {
134 if (blkio_blkg_waiting(&blkg->stats))
135 return;
136 if (blkg == curr_blkg)
137 return;
138 blkg->stats.start_group_wait_time = sched_clock();
139 blkio_mark_blkg_waiting(&blkg->stats);
140 }
141
142 /* This should be called with the blkg->stats_lock held. */
143 static void blkio_update_group_wait_time(struct blkio_group_stats *stats)
144 {
145 unsigned long long now;
146
147 if (!blkio_blkg_waiting(stats))
148 return;
149
150 now = sched_clock();
151 if (time_after64(now, stats->start_group_wait_time))
152 stats->group_wait_time += now - stats->start_group_wait_time;
153 blkio_clear_blkg_waiting(stats);
154 }
155
156 /* This should be called with the blkg->stats_lock held. */
157 static void blkio_end_empty_time(struct blkio_group_stats *stats)
158 {
159 unsigned long long now;
160
161 if (!blkio_blkg_empty(stats))
162 return;
163
164 now = sched_clock();
165 if (time_after64(now, stats->start_empty_time))
166 stats->empty_time += now - stats->start_empty_time;
167 blkio_clear_blkg_empty(stats);
168 }
169
170 void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg)
171 {
172 unsigned long flags;
173
174 spin_lock_irqsave(&blkg->stats_lock, flags);
175 BUG_ON(blkio_blkg_idling(&blkg->stats));
176 blkg->stats.start_idle_time = sched_clock();
177 blkio_mark_blkg_idling(&blkg->stats);
178 spin_unlock_irqrestore(&blkg->stats_lock, flags);
179 }
180 EXPORT_SYMBOL_GPL(blkiocg_update_set_idle_time_stats);
181
182 void blkiocg_update_idle_time_stats(struct blkio_group *blkg)
183 {
184 unsigned long flags;
185 unsigned long long now;
186 struct blkio_group_stats *stats;
187
188 spin_lock_irqsave(&blkg->stats_lock, flags);
189 stats = &blkg->stats;
190 if (blkio_blkg_idling(stats)) {
191 now = sched_clock();
192 if (time_after64(now, stats->start_idle_time))
193 stats->idle_time += now - stats->start_idle_time;
194 blkio_clear_blkg_idling(stats);
195 }
196 spin_unlock_irqrestore(&blkg->stats_lock, flags);
197 }
198 EXPORT_SYMBOL_GPL(blkiocg_update_idle_time_stats);
199
200 void blkiocg_update_avg_queue_size_stats(struct blkio_group *blkg)
201 {
202 unsigned long flags;
203 struct blkio_group_stats *stats;
204
205 spin_lock_irqsave(&blkg->stats_lock, flags);
206 stats = &blkg->stats;
207 stats->avg_queue_size_sum +=
208 stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] +
209 stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE];
210 stats->avg_queue_size_samples++;
211 blkio_update_group_wait_time(stats);
212 spin_unlock_irqrestore(&blkg->stats_lock, flags);
213 }
214 EXPORT_SYMBOL_GPL(blkiocg_update_avg_queue_size_stats);
215
216 void blkiocg_set_start_empty_time(struct blkio_group *blkg)
217 {
218 unsigned long flags;
219 struct blkio_group_stats *stats;
220
221 spin_lock_irqsave(&blkg->stats_lock, flags);
222 stats = &blkg->stats;
223
224 if (stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] ||
225 stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE]) {
226 spin_unlock_irqrestore(&blkg->stats_lock, flags);
227 return;
228 }
229
230 /*
231 * group is already marked empty. This can happen if cfqq got new
232 * request in parent group and moved to this group while being added
233 * to service tree. Just ignore the event and move on.
234 */
235 if(blkio_blkg_empty(stats)) {
236 spin_unlock_irqrestore(&blkg->stats_lock, flags);
237 return;
238 }
239
240 stats->start_empty_time = sched_clock();
241 blkio_mark_blkg_empty(stats);
242 spin_unlock_irqrestore(&blkg->stats_lock, flags);
243 }
244 EXPORT_SYMBOL_GPL(blkiocg_set_start_empty_time);
245
246 void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
247 unsigned long dequeue)
248 {
249 blkg->stats.dequeue += dequeue;
250 }
251 EXPORT_SYMBOL_GPL(blkiocg_update_dequeue_stats);
252 #else
253 static inline void blkio_set_start_group_wait_time(struct blkio_group *blkg,
254 struct blkio_group *curr_blkg) {}
255 static inline void blkio_end_empty_time(struct blkio_group_stats *stats) {}
256 #endif
257
258 void blkiocg_update_io_add_stats(struct blkio_group *blkg,
259 struct blkio_group *curr_blkg, bool direction,
260 bool sync)
261 {
262 unsigned long flags;
263
264 spin_lock_irqsave(&blkg->stats_lock, flags);
265 blkio_add_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED], 1, direction,
266 sync);
267 blkio_end_empty_time(&blkg->stats);
268 blkio_set_start_group_wait_time(blkg, curr_blkg);
269 spin_unlock_irqrestore(&blkg->stats_lock, flags);
270 }
271 EXPORT_SYMBOL_GPL(blkiocg_update_io_add_stats);
272
273 void blkiocg_update_io_remove_stats(struct blkio_group *blkg,
274 bool direction, bool sync)
275 {
276 unsigned long flags;
277
278 spin_lock_irqsave(&blkg->stats_lock, flags);
279 blkio_check_and_dec_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED],
280 direction, sync);
281 spin_unlock_irqrestore(&blkg->stats_lock, flags);
282 }
283 EXPORT_SYMBOL_GPL(blkiocg_update_io_remove_stats);
284
285 void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time)
286 {
287 unsigned long flags;
288
289 spin_lock_irqsave(&blkg->stats_lock, flags);
290 blkg->stats.time += time;
291 spin_unlock_irqrestore(&blkg->stats_lock, flags);
292 }
293 EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);
294
295 void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
296 uint64_t bytes, bool direction, bool sync)
297 {
298 struct blkio_group_stats *stats;
299 unsigned long flags;
300
301 spin_lock_irqsave(&blkg->stats_lock, flags);
302 stats = &blkg->stats;
303 stats->sectors += bytes >> 9;
304 blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICED], 1, direction,
305 sync);
306 blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_BYTES], bytes,
307 direction, sync);
308 spin_unlock_irqrestore(&blkg->stats_lock, flags);
309 }
310 EXPORT_SYMBOL_GPL(blkiocg_update_dispatch_stats);
311
312 void blkiocg_update_completion_stats(struct blkio_group *blkg,
313 uint64_t start_time, uint64_t io_start_time, bool direction, bool sync)
314 {
315 struct blkio_group_stats *stats;
316 unsigned long flags;
317 unsigned long long now = sched_clock();
318
319 spin_lock_irqsave(&blkg->stats_lock, flags);
320 stats = &blkg->stats;
321 if (time_after64(now, io_start_time))
322 blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_TIME],
323 now - io_start_time, direction, sync);
324 if (time_after64(io_start_time, start_time))
325 blkio_add_stat(stats->stat_arr[BLKIO_STAT_WAIT_TIME],
326 io_start_time - start_time, direction, sync);
327 spin_unlock_irqrestore(&blkg->stats_lock, flags);
328 }
329 EXPORT_SYMBOL_GPL(blkiocg_update_completion_stats);
330
331 void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction,
332 bool sync)
333 {
334 unsigned long flags;
335
336 spin_lock_irqsave(&blkg->stats_lock, flags);
337 blkio_add_stat(blkg->stats.stat_arr[BLKIO_STAT_MERGED], 1, direction,
338 sync);
339 spin_unlock_irqrestore(&blkg->stats_lock, flags);
340 }
341 EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats);
342
343 void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
344 struct blkio_group *blkg, void *key, dev_t dev)
345 {
346 unsigned long flags;
347
348 spin_lock_irqsave(&blkcg->lock, flags);
349 spin_lock_init(&blkg->stats_lock);
350 rcu_assign_pointer(blkg->key, key);
351 blkg->blkcg_id = css_id(&blkcg->css);
352 hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
353 spin_unlock_irqrestore(&blkcg->lock, flags);
354 /* Need to take css reference ? */
355 cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
356 blkg->dev = dev;
357 }
358 EXPORT_SYMBOL_GPL(blkiocg_add_blkio_group);
359
360 static void __blkiocg_del_blkio_group(struct blkio_group *blkg)
361 {
362 hlist_del_init_rcu(&blkg->blkcg_node);
363 blkg->blkcg_id = 0;
364 }
365
366 /*
367 * returns 0 if blkio_group was still on cgroup list. Otherwise returns 1
368 * indicating that blk_group was unhashed by the time we got to it.
369 */
370 int blkiocg_del_blkio_group(struct blkio_group *blkg)
371 {
372 struct blkio_cgroup *blkcg;
373 unsigned long flags;
374 struct cgroup_subsys_state *css;
375 int ret = 1;
376
377 rcu_read_lock();
378 css = css_lookup(&blkio_subsys, blkg->blkcg_id);
379 if (css) {
380 blkcg = container_of(css, struct blkio_cgroup, css);
381 spin_lock_irqsave(&blkcg->lock, flags);
382 if (!hlist_unhashed(&blkg->blkcg_node)) {
383 __blkiocg_del_blkio_group(blkg);
384 ret = 0;
385 }
386 spin_unlock_irqrestore(&blkcg->lock, flags);
387 }
388
389 rcu_read_unlock();
390 return ret;
391 }
392 EXPORT_SYMBOL_GPL(blkiocg_del_blkio_group);
393
394 /* called under rcu_read_lock(). */
395 struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key)
396 {
397 struct blkio_group *blkg;
398 struct hlist_node *n;
399 void *__key;
400
401 hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
402 __key = blkg->key;
403 if (__key == key)
404 return blkg;
405 }
406
407 return NULL;
408 }
409 EXPORT_SYMBOL_GPL(blkiocg_lookup_group);
410
411 #define SHOW_FUNCTION(__VAR) \
412 static u64 blkiocg_##__VAR##_read(struct cgroup *cgroup, \
413 struct cftype *cftype) \
414 { \
415 struct blkio_cgroup *blkcg; \
416 \
417 blkcg = cgroup_to_blkio_cgroup(cgroup); \
418 return (u64)blkcg->__VAR; \
419 }
420
421 SHOW_FUNCTION(weight);
422 #undef SHOW_FUNCTION
423
424 static int
425 blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val)
426 {
427 struct blkio_cgroup *blkcg;
428 struct blkio_group *blkg;
429 struct hlist_node *n;
430 struct blkio_policy_type *blkiop;
431 struct blkio_policy_node *pn;
432
433 if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
434 return -EINVAL;
435
436 blkcg = cgroup_to_blkio_cgroup(cgroup);
437 spin_lock(&blkio_list_lock);
438 spin_lock_irq(&blkcg->lock);
439 blkcg->weight = (unsigned int)val;
440
441 hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
442 pn = blkio_policy_search_node(blkcg, blkg->dev);
443
444 if (pn)
445 continue;
446
447 list_for_each_entry(blkiop, &blkio_list, list)
448 blkiop->ops.blkio_update_group_weight_fn(blkg,
449 blkcg->weight);
450 }
451 spin_unlock_irq(&blkcg->lock);
452 spin_unlock(&blkio_list_lock);
453 return 0;
454 }
455
456 static int
457 blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
458 {
459 struct blkio_cgroup *blkcg;
460 struct blkio_group *blkg;
461 struct blkio_group_stats *stats;
462 struct hlist_node *n;
463 uint64_t queued[BLKIO_STAT_TOTAL];
464 int i;
465 #ifdef CONFIG_DEBUG_BLK_CGROUP
466 bool idling, waiting, empty;
467 unsigned long long now = sched_clock();
468 #endif
469
470 blkcg = cgroup_to_blkio_cgroup(cgroup);
471 spin_lock_irq(&blkcg->lock);
472 hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
473 spin_lock(&blkg->stats_lock);
474 stats = &blkg->stats;
475 #ifdef CONFIG_DEBUG_BLK_CGROUP
476 idling = blkio_blkg_idling(stats);
477 waiting = blkio_blkg_waiting(stats);
478 empty = blkio_blkg_empty(stats);
479 #endif
480 for (i = 0; i < BLKIO_STAT_TOTAL; i++)
481 queued[i] = stats->stat_arr[BLKIO_STAT_QUEUED][i];
482 memset(stats, 0, sizeof(struct blkio_group_stats));
483 for (i = 0; i < BLKIO_STAT_TOTAL; i++)
484 stats->stat_arr[BLKIO_STAT_QUEUED][i] = queued[i];
485 #ifdef CONFIG_DEBUG_BLK_CGROUP
486 if (idling) {
487 blkio_mark_blkg_idling(stats);
488 stats->start_idle_time = now;
489 }
490 if (waiting) {
491 blkio_mark_blkg_waiting(stats);
492 stats->start_group_wait_time = now;
493 }
494 if (empty) {
495 blkio_mark_blkg_empty(stats);
496 stats->start_empty_time = now;
497 }
498 #endif
499 spin_unlock(&blkg->stats_lock);
500 }
501 spin_unlock_irq(&blkcg->lock);
502 return 0;
503 }
504
505 static void blkio_get_key_name(enum stat_sub_type type, dev_t dev, char *str,
506 int chars_left, bool diskname_only)
507 {
508 snprintf(str, chars_left, "%d:%d", MAJOR(dev), MINOR(dev));
509 chars_left -= strlen(str);
510 if (chars_left <= 0) {
511 printk(KERN_WARNING
512 "Possibly incorrect cgroup stat display format");
513 return;
514 }
515 if (diskname_only)
516 return;
517 switch (type) {
518 case BLKIO_STAT_READ:
519 strlcat(str, " Read", chars_left);
520 break;
521 case BLKIO_STAT_WRITE:
522 strlcat(str, " Write", chars_left);
523 break;
524 case BLKIO_STAT_SYNC:
525 strlcat(str, " Sync", chars_left);
526 break;
527 case BLKIO_STAT_ASYNC:
528 strlcat(str, " Async", chars_left);
529 break;
530 case BLKIO_STAT_TOTAL:
531 strlcat(str, " Total", chars_left);
532 break;
533 default:
534 strlcat(str, " Invalid", chars_left);
535 }
536 }
537
538 static uint64_t blkio_fill_stat(char *str, int chars_left, uint64_t val,
539 struct cgroup_map_cb *cb, dev_t dev)
540 {
541 blkio_get_key_name(0, dev, str, chars_left, true);
542 cb->fill(cb, str, val);
543 return val;
544 }
545
546 /* This should be called with blkg->stats_lock held */
547 static uint64_t blkio_get_stat(struct blkio_group *blkg,
548 struct cgroup_map_cb *cb, dev_t dev, enum stat_type type)
549 {
550 uint64_t disk_total;
551 char key_str[MAX_KEY_LEN];
552 enum stat_sub_type sub_type;
553
554 if (type == BLKIO_STAT_TIME)
555 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
556 blkg->stats.time, cb, dev);
557 if (type == BLKIO_STAT_SECTORS)
558 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
559 blkg->stats.sectors, cb, dev);
560 #ifdef CONFIG_DEBUG_BLK_CGROUP
561 if (type == BLKIO_STAT_AVG_QUEUE_SIZE) {
562 uint64_t sum = blkg->stats.avg_queue_size_sum;
563 uint64_t samples = blkg->stats.avg_queue_size_samples;
564 if (samples)
565 do_div(sum, samples);
566 else
567 sum = 0;
568 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, sum, cb, dev);
569 }
570 if (type == BLKIO_STAT_GROUP_WAIT_TIME)
571 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
572 blkg->stats.group_wait_time, cb, dev);
573 if (type == BLKIO_STAT_IDLE_TIME)
574 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
575 blkg->stats.idle_time, cb, dev);
576 if (type == BLKIO_STAT_EMPTY_TIME)
577 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
578 blkg->stats.empty_time, cb, dev);
579 if (type == BLKIO_STAT_DEQUEUE)
580 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
581 blkg->stats.dequeue, cb, dev);
582 #endif
583
584 for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL;
585 sub_type++) {
586 blkio_get_key_name(sub_type, dev, key_str, MAX_KEY_LEN, false);
587 cb->fill(cb, key_str, blkg->stats.stat_arr[type][sub_type]);
588 }
589 disk_total = blkg->stats.stat_arr[type][BLKIO_STAT_READ] +
590 blkg->stats.stat_arr[type][BLKIO_STAT_WRITE];
591 blkio_get_key_name(BLKIO_STAT_TOTAL, dev, key_str, MAX_KEY_LEN, false);
592 cb->fill(cb, key_str, disk_total);
593 return disk_total;
594 }
595
596 #define SHOW_FUNCTION_PER_GROUP(__VAR, type, show_total) \
597 static int blkiocg_##__VAR##_read(struct cgroup *cgroup, \
598 struct cftype *cftype, struct cgroup_map_cb *cb) \
599 { \
600 struct blkio_cgroup *blkcg; \
601 struct blkio_group *blkg; \
602 struct hlist_node *n; \
603 uint64_t cgroup_total = 0; \
604 \
605 if (!cgroup_lock_live_group(cgroup)) \
606 return -ENODEV; \
607 \
608 blkcg = cgroup_to_blkio_cgroup(cgroup); \
609 rcu_read_lock(); \
610 hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {\
611 if (blkg->dev) { \
612 spin_lock_irq(&blkg->stats_lock); \
613 cgroup_total += blkio_get_stat(blkg, cb, \
614 blkg->dev, type); \
615 spin_unlock_irq(&blkg->stats_lock); \
616 } \
617 } \
618 if (show_total) \
619 cb->fill(cb, "Total", cgroup_total); \
620 rcu_read_unlock(); \
621 cgroup_unlock(); \
622 return 0; \
623 }
624
625 SHOW_FUNCTION_PER_GROUP(time, BLKIO_STAT_TIME, 0);
626 SHOW_FUNCTION_PER_GROUP(sectors, BLKIO_STAT_SECTORS, 0);
627 SHOW_FUNCTION_PER_GROUP(io_service_bytes, BLKIO_STAT_SERVICE_BYTES, 1);
628 SHOW_FUNCTION_PER_GROUP(io_serviced, BLKIO_STAT_SERVICED, 1);
629 SHOW_FUNCTION_PER_GROUP(io_service_time, BLKIO_STAT_SERVICE_TIME, 1);
630 SHOW_FUNCTION_PER_GROUP(io_wait_time, BLKIO_STAT_WAIT_TIME, 1);
631 SHOW_FUNCTION_PER_GROUP(io_merged, BLKIO_STAT_MERGED, 1);
632 SHOW_FUNCTION_PER_GROUP(io_queued, BLKIO_STAT_QUEUED, 1);
633 #ifdef CONFIG_DEBUG_BLK_CGROUP
634 SHOW_FUNCTION_PER_GROUP(dequeue, BLKIO_STAT_DEQUEUE, 0);
635 SHOW_FUNCTION_PER_GROUP(avg_queue_size, BLKIO_STAT_AVG_QUEUE_SIZE, 0);
636 SHOW_FUNCTION_PER_GROUP(group_wait_time, BLKIO_STAT_GROUP_WAIT_TIME, 0);
637 SHOW_FUNCTION_PER_GROUP(idle_time, BLKIO_STAT_IDLE_TIME, 0);
638 SHOW_FUNCTION_PER_GROUP(empty_time, BLKIO_STAT_EMPTY_TIME, 0);
639 #endif
640 #undef SHOW_FUNCTION_PER_GROUP
641
642 static int blkio_check_dev_num(dev_t dev)
643 {
644 int part = 0;
645 struct gendisk *disk;
646
647 disk = get_gendisk(dev, &part);
648 if (!disk || part)
649 return -ENODEV;
650
651 return 0;
652 }
653
654 static int blkio_policy_parse_and_set(char *buf,
655 struct blkio_policy_node *newpn)
656 {
657 char *s[4], *p, *major_s = NULL, *minor_s = NULL;
658 int ret;
659 unsigned long major, minor, temp;
660 int i = 0;
661 dev_t dev;
662
663 memset(s, 0, sizeof(s));
664
665 while ((p = strsep(&buf, " ")) != NULL) {
666 if (!*p)
667 continue;
668
669 s[i++] = p;
670
671 /* Prevent from inputing too many things */
672 if (i == 3)
673 break;
674 }
675
676 if (i != 2)
677 return -EINVAL;
678
679 p = strsep(&s[0], ":");
680 if (p != NULL)
681 major_s = p;
682 else
683 return -EINVAL;
684
685 minor_s = s[0];
686 if (!minor_s)
687 return -EINVAL;
688
689 ret = strict_strtoul(major_s, 10, &major);
690 if (ret)
691 return -EINVAL;
692
693 ret = strict_strtoul(minor_s, 10, &minor);
694 if (ret)
695 return -EINVAL;
696
697 dev = MKDEV(major, minor);
698
699 ret = blkio_check_dev_num(dev);
700 if (ret)
701 return ret;
702
703 newpn->dev = dev;
704
705 if (s[1] == NULL)
706 return -EINVAL;
707
708 ret = strict_strtoul(s[1], 10, &temp);
709 if (ret || (temp < BLKIO_WEIGHT_MIN && temp > 0) ||
710 temp > BLKIO_WEIGHT_MAX)
711 return -EINVAL;
712
713 newpn->weight = temp;
714
715 return 0;
716 }
717
718 unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
719 dev_t dev)
720 {
721 struct blkio_policy_node *pn;
722
723 pn = blkio_policy_search_node(blkcg, dev);
724 if (pn)
725 return pn->weight;
726 else
727 return blkcg->weight;
728 }
729 EXPORT_SYMBOL_GPL(blkcg_get_weight);
730
731
732 static int blkiocg_weight_device_write(struct cgroup *cgrp, struct cftype *cft,
733 const char *buffer)
734 {
735 int ret = 0;
736 char *buf;
737 struct blkio_policy_node *newpn, *pn;
738 struct blkio_cgroup *blkcg;
739 struct blkio_group *blkg;
740 int keep_newpn = 0;
741 struct hlist_node *n;
742 struct blkio_policy_type *blkiop;
743
744 buf = kstrdup(buffer, GFP_KERNEL);
745 if (!buf)
746 return -ENOMEM;
747
748 newpn = kzalloc(sizeof(*newpn), GFP_KERNEL);
749 if (!newpn) {
750 ret = -ENOMEM;
751 goto free_buf;
752 }
753
754 ret = blkio_policy_parse_and_set(buf, newpn);
755 if (ret)
756 goto free_newpn;
757
758 blkcg = cgroup_to_blkio_cgroup(cgrp);
759
760 spin_lock_irq(&blkcg->lock);
761
762 pn = blkio_policy_search_node(blkcg, newpn->dev);
763 if (!pn) {
764 if (newpn->weight != 0) {
765 blkio_policy_insert_node(blkcg, newpn);
766 keep_newpn = 1;
767 }
768 spin_unlock_irq(&blkcg->lock);
769 goto update_io_group;
770 }
771
772 if (newpn->weight == 0) {
773 /* weight == 0 means deleteing a specific weight */
774 blkio_policy_delete_node(pn);
775 spin_unlock_irq(&blkcg->lock);
776 goto update_io_group;
777 }
778 spin_unlock_irq(&blkcg->lock);
779
780 pn->weight = newpn->weight;
781
782 update_io_group:
783 /* update weight for each cfqg */
784 spin_lock(&blkio_list_lock);
785 spin_lock_irq(&blkcg->lock);
786
787 hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
788 if (newpn->dev == blkg->dev) {
789 list_for_each_entry(blkiop, &blkio_list, list)
790 blkiop->ops.blkio_update_group_weight_fn(blkg,
791 newpn->weight ?
792 newpn->weight :
793 blkcg->weight);
794 }
795 }
796
797 spin_unlock_irq(&blkcg->lock);
798 spin_unlock(&blkio_list_lock);
799
800 free_newpn:
801 if (!keep_newpn)
802 kfree(newpn);
803 free_buf:
804 kfree(buf);
805 return ret;
806 }
807
808 static int blkiocg_weight_device_read(struct cgroup *cgrp, struct cftype *cft,
809 struct seq_file *m)
810 {
811 struct blkio_cgroup *blkcg;
812 struct blkio_policy_node *pn;
813
814 seq_printf(m, "dev\tweight\n");
815
816 blkcg = cgroup_to_blkio_cgroup(cgrp);
817 if (!list_empty(&blkcg->policy_list)) {
818 spin_lock_irq(&blkcg->lock);
819 list_for_each_entry(pn, &blkcg->policy_list, node) {
820 seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
821 MINOR(pn->dev), pn->weight);
822 }
823 spin_unlock_irq(&blkcg->lock);
824 }
825
826 return 0;
827 }
828
829 struct cftype blkio_files[] = {
830 {
831 .name = "weight_device",
832 .read_seq_string = blkiocg_weight_device_read,
833 .write_string = blkiocg_weight_device_write,
834 .max_write_len = 256,
835 },
836 {
837 .name = "weight",
838 .read_u64 = blkiocg_weight_read,
839 .write_u64 = blkiocg_weight_write,
840 },
841 {
842 .name = "time",
843 .read_map = blkiocg_time_read,
844 },
845 {
846 .name = "sectors",
847 .read_map = blkiocg_sectors_read,
848 },
849 {
850 .name = "io_service_bytes",
851 .read_map = blkiocg_io_service_bytes_read,
852 },
853 {
854 .name = "io_serviced",
855 .read_map = blkiocg_io_serviced_read,
856 },
857 {
858 .name = "io_service_time",
859 .read_map = blkiocg_io_service_time_read,
860 },
861 {
862 .name = "io_wait_time",
863 .read_map = blkiocg_io_wait_time_read,
864 },
865 {
866 .name = "io_merged",
867 .read_map = blkiocg_io_merged_read,
868 },
869 {
870 .name = "io_queued",
871 .read_map = blkiocg_io_queued_read,
872 },
873 {
874 .name = "reset_stats",
875 .write_u64 = blkiocg_reset_stats,
876 },
877 #ifdef CONFIG_DEBUG_BLK_CGROUP
878 {
879 .name = "avg_queue_size",
880 .read_map = blkiocg_avg_queue_size_read,
881 },
882 {
883 .name = "group_wait_time",
884 .read_map = blkiocg_group_wait_time_read,
885 },
886 {
887 .name = "idle_time",
888 .read_map = blkiocg_idle_time_read,
889 },
890 {
891 .name = "empty_time",
892 .read_map = blkiocg_empty_time_read,
893 },
894 {
895 .name = "dequeue",
896 .read_map = blkiocg_dequeue_read,
897 },
898 #endif
899 };
900
901 static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
902 {
903 return cgroup_add_files(cgroup, subsys, blkio_files,
904 ARRAY_SIZE(blkio_files));
905 }
906
907 static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
908 {
909 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
910 unsigned long flags;
911 struct blkio_group *blkg;
912 void *key;
913 struct blkio_policy_type *blkiop;
914 struct blkio_policy_node *pn, *pntmp;
915
916 rcu_read_lock();
917 do {
918 spin_lock_irqsave(&blkcg->lock, flags);
919
920 if (hlist_empty(&blkcg->blkg_list)) {
921 spin_unlock_irqrestore(&blkcg->lock, flags);
922 break;
923 }
924
925 blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group,
926 blkcg_node);
927 key = rcu_dereference(blkg->key);
928 __blkiocg_del_blkio_group(blkg);
929
930 spin_unlock_irqrestore(&blkcg->lock, flags);
931
932 /*
933 * This blkio_group is being unlinked as associated cgroup is
934 * going away. Let all the IO controlling policies know about
935 * this event. Currently this is static call to one io
936 * controlling policy. Once we have more policies in place, we
937 * need some dynamic registration of callback function.
938 */
939 spin_lock(&blkio_list_lock);
940 list_for_each_entry(blkiop, &blkio_list, list)
941 blkiop->ops.blkio_unlink_group_fn(key, blkg);
942 spin_unlock(&blkio_list_lock);
943 } while (1);
944
945 list_for_each_entry_safe(pn, pntmp, &blkcg->policy_list, node) {
946 blkio_policy_delete_node(pn);
947 kfree(pn);
948 }
949
950 free_css_id(&blkio_subsys, &blkcg->css);
951 rcu_read_unlock();
952 if (blkcg != &blkio_root_cgroup)
953 kfree(blkcg);
954 }
955
956 static struct cgroup_subsys_state *
957 blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
958 {
959 struct blkio_cgroup *blkcg;
960 struct cgroup *parent = cgroup->parent;
961
962 if (!parent) {
963 blkcg = &blkio_root_cgroup;
964 goto done;
965 }
966
967 /* Currently we do not support hierarchy deeper than two level (0,1) */
968 if (parent != cgroup->top_cgroup)
969 return ERR_PTR(-EINVAL);
970
971 blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
972 if (!blkcg)
973 return ERR_PTR(-ENOMEM);
974
975 blkcg->weight = BLKIO_WEIGHT_DEFAULT;
976 done:
977 spin_lock_init(&blkcg->lock);
978 INIT_HLIST_HEAD(&blkcg->blkg_list);
979
980 INIT_LIST_HEAD(&blkcg->policy_list);
981 return &blkcg->css;
982 }
983
984 /*
985 * We cannot support shared io contexts, as we have no mean to support
986 * two tasks with the same ioc in two different groups without major rework
987 * of the main cic data structures. For now we allow a task to change
988 * its cgroup only if it's the only owner of its ioc.
989 */
990 static int blkiocg_can_attach(struct cgroup_subsys *subsys,
991 struct cgroup *cgroup, struct task_struct *tsk,
992 bool threadgroup)
993 {
994 struct io_context *ioc;
995 int ret = 0;
996
997 /* task_lock() is needed to avoid races with exit_io_context() */
998 task_lock(tsk);
999 ioc = tsk->io_context;
1000 if (ioc && atomic_read(&ioc->nr_tasks) > 1)
1001 ret = -EINVAL;
1002 task_unlock(tsk);
1003
1004 return ret;
1005 }
1006
1007 static void blkiocg_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup,
1008 struct cgroup *prev, struct task_struct *tsk,
1009 bool threadgroup)
1010 {
1011 struct io_context *ioc;
1012
1013 task_lock(tsk);
1014 ioc = tsk->io_context;
1015 if (ioc)
1016 ioc->cgroup_changed = 1;
1017 task_unlock(tsk);
1018 }
1019
1020 void blkio_policy_register(struct blkio_policy_type *blkiop)
1021 {
1022 spin_lock(&blkio_list_lock);
1023 list_add_tail(&blkiop->list, &blkio_list);
1024 spin_unlock(&blkio_list_lock);
1025 }
1026 EXPORT_SYMBOL_GPL(blkio_policy_register);
1027
1028 void blkio_policy_unregister(struct blkio_policy_type *blkiop)
1029 {
1030 spin_lock(&blkio_list_lock);
1031 list_del_init(&blkiop->list);
1032 spin_unlock(&blkio_list_lock);
1033 }
1034 EXPORT_SYMBOL_GPL(blkio_policy_unregister);
1035
1036 static int __init init_cgroup_blkio(void)
1037 {
1038 return cgroup_load_subsys(&blkio_subsys);
1039 }
1040
1041 static void __exit exit_cgroup_blkio(void)
1042 {
1043 cgroup_unload_subsys(&blkio_subsys);
1044 }
1045
1046 module_init(init_cgroup_blkio);
1047 module_exit(exit_cgroup_blkio);
1048 MODULE_LICENSE("GPL");
Linux with added FPC-III support