blk-cgroup: move some fields of unaccounted_time file under right config option
[linux-2.6.git] / block / blk-cgroup.c
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 /* for encoding cft->private value on file */
41 #define BLKIOFILE_PRIVATE(x, val)       (((x) << 16) | (val))
42 /* What policy owns the file, proportional or throttle */
43 #define BLKIOFILE_POLICY(val)           (((val) >> 16) & 0xffff)
44 #define BLKIOFILE_ATTR(val)             ((val) & 0xffff)
45
46 struct cgroup_subsys blkio_subsys = {
47         .name = "blkio",
48         .create = blkiocg_create,
49         .can_attach = blkiocg_can_attach,
50         .attach = blkiocg_attach,
51         .destroy = blkiocg_destroy,
52         .populate = blkiocg_populate,
53 #ifdef CONFIG_BLK_CGROUP
54         /* note: blkio_subsys_id is otherwise defined in blk-cgroup.h */
55         .subsys_id = blkio_subsys_id,
56 #endif
57         .use_id = 1,
58         .module = THIS_MODULE,
59 };
60 EXPORT_SYMBOL_GPL(blkio_subsys);
61
62 static inline void blkio_policy_insert_node(struct blkio_cgroup *blkcg,
63                                             struct blkio_policy_node *pn)
64 {
65         list_add(&pn->node, &blkcg->policy_list);
66 }
67
68 static inline bool cftype_blkg_same_policy(struct cftype *cft,
69                         struct blkio_group *blkg)
70 {
71         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
72
73         if (blkg->plid == plid)
74                 return 1;
75
76         return 0;
77 }
78
79 /* Determines if policy node matches cgroup file being accessed */
80 static inline bool pn_matches_cftype(struct cftype *cft,
81                         struct blkio_policy_node *pn)
82 {
83         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
84         int fileid = BLKIOFILE_ATTR(cft->private);
85
86         return (plid == pn->plid && fileid == pn->fileid);
87 }
88
89 /* Must be called with blkcg->lock held */
90 static inline void blkio_policy_delete_node(struct blkio_policy_node *pn)
91 {
92         list_del(&pn->node);
93 }
94
95 /* Must be called with blkcg->lock held */
96 static struct blkio_policy_node *
97 blkio_policy_search_node(const struct blkio_cgroup *blkcg, dev_t dev,
98                 enum blkio_policy_id plid, int fileid)
99 {
100         struct blkio_policy_node *pn;
101
102         list_for_each_entry(pn, &blkcg->policy_list, node) {
103                 if (pn->dev == dev && pn->plid == plid && pn->fileid == fileid)
104                         return pn;
105         }
106
107         return NULL;
108 }
109
110 struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
111 {
112         return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
113                             struct blkio_cgroup, css);
114 }
115 EXPORT_SYMBOL_GPL(cgroup_to_blkio_cgroup);
116
117 struct blkio_cgroup *task_blkio_cgroup(struct task_struct *tsk)
118 {
119         return container_of(task_subsys_state(tsk, blkio_subsys_id),
120                             struct blkio_cgroup, css);
121 }
122 EXPORT_SYMBOL_GPL(task_blkio_cgroup);
123
124 static inline void
125 blkio_update_group_weight(struct blkio_group *blkg, unsigned int weight)
126 {
127         struct blkio_policy_type *blkiop;
128
129         list_for_each_entry(blkiop, &blkio_list, list) {
130                 /* If this policy does not own the blkg, do not send updates */
131                 if (blkiop->plid != blkg->plid)
132                         continue;
133                 if (blkiop->ops.blkio_update_group_weight_fn)
134                         blkiop->ops.blkio_update_group_weight_fn(blkg->key,
135                                                         blkg, weight);
136         }
137 }
138
139 static inline void blkio_update_group_bps(struct blkio_group *blkg, u64 bps,
140                                 int fileid)
141 {
142         struct blkio_policy_type *blkiop;
143
144         list_for_each_entry(blkiop, &blkio_list, list) {
145
146                 /* If this policy does not own the blkg, do not send updates */
147                 if (blkiop->plid != blkg->plid)
148                         continue;
149
150                 if (fileid == BLKIO_THROTL_read_bps_device
151                     && blkiop->ops.blkio_update_group_read_bps_fn)
152                         blkiop->ops.blkio_update_group_read_bps_fn(blkg->key,
153                                                                 blkg, bps);
154
155                 if (fileid == BLKIO_THROTL_write_bps_device
156                     && blkiop->ops.blkio_update_group_write_bps_fn)
157                         blkiop->ops.blkio_update_group_write_bps_fn(blkg->key,
158                                                                 blkg, bps);
159         }
160 }
161
162 static inline void blkio_update_group_iops(struct blkio_group *blkg,
163                         unsigned int iops, int fileid)
164 {
165         struct blkio_policy_type *blkiop;
166
167         list_for_each_entry(blkiop, &blkio_list, list) {
168
169                 /* If this policy does not own the blkg, do not send updates */
170                 if (blkiop->plid != blkg->plid)
171                         continue;
172
173                 if (fileid == BLKIO_THROTL_read_iops_device
174                     && blkiop->ops.blkio_update_group_read_iops_fn)
175                         blkiop->ops.blkio_update_group_read_iops_fn(blkg->key,
176                                                                 blkg, iops);
177
178                 if (fileid == BLKIO_THROTL_write_iops_device
179                     && blkiop->ops.blkio_update_group_write_iops_fn)
180                         blkiop->ops.blkio_update_group_write_iops_fn(blkg->key,
181                                                                 blkg,iops);
182         }
183 }
184
185 /*
186  * Add to the appropriate stat variable depending on the request type.
187  * This should be called with the blkg->stats_lock held.
188  */
189 static void blkio_add_stat(uint64_t *stat, uint64_t add, bool direction,
190                                 bool sync)
191 {
192         if (direction)
193                 stat[BLKIO_STAT_WRITE] += add;
194         else
195                 stat[BLKIO_STAT_READ] += add;
196         if (sync)
197                 stat[BLKIO_STAT_SYNC] += add;
198         else
199                 stat[BLKIO_STAT_ASYNC] += add;
200 }
201
202 /*
203  * Decrements the appropriate stat variable if non-zero depending on the
204  * request type. Panics on value being zero.
205  * This should be called with the blkg->stats_lock held.
206  */
207 static void blkio_check_and_dec_stat(uint64_t *stat, bool direction, bool sync)
208 {
209         if (direction) {
210                 BUG_ON(stat[BLKIO_STAT_WRITE] == 0);
211                 stat[BLKIO_STAT_WRITE]--;
212         } else {
213                 BUG_ON(stat[BLKIO_STAT_READ] == 0);
214                 stat[BLKIO_STAT_READ]--;
215         }
216         if (sync) {
217                 BUG_ON(stat[BLKIO_STAT_SYNC] == 0);
218                 stat[BLKIO_STAT_SYNC]--;
219         } else {
220                 BUG_ON(stat[BLKIO_STAT_ASYNC] == 0);
221                 stat[BLKIO_STAT_ASYNC]--;
222         }
223 }
224
225 #ifdef CONFIG_DEBUG_BLK_CGROUP
226 /* This should be called with the blkg->stats_lock held. */
227 static void blkio_set_start_group_wait_time(struct blkio_group *blkg,
228                                                 struct blkio_group *curr_blkg)
229 {
230         if (blkio_blkg_waiting(&blkg->stats))
231                 return;
232         if (blkg == curr_blkg)
233                 return;
234         blkg->stats.start_group_wait_time = sched_clock();
235         blkio_mark_blkg_waiting(&blkg->stats);
236 }
237
238 /* This should be called with the blkg->stats_lock held. */
239 static void blkio_update_group_wait_time(struct blkio_group_stats *stats)
240 {
241         unsigned long long now;
242
243         if (!blkio_blkg_waiting(stats))
244                 return;
245
246         now = sched_clock();
247         if (time_after64(now, stats->start_group_wait_time))
248                 stats->group_wait_time += now - stats->start_group_wait_time;
249         blkio_clear_blkg_waiting(stats);
250 }
251
252 /* This should be called with the blkg->stats_lock held. */
253 static void blkio_end_empty_time(struct blkio_group_stats *stats)
254 {
255         unsigned long long now;
256
257         if (!blkio_blkg_empty(stats))
258                 return;
259
260         now = sched_clock();
261         if (time_after64(now, stats->start_empty_time))
262                 stats->empty_time += now - stats->start_empty_time;
263         blkio_clear_blkg_empty(stats);
264 }
265
266 void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg)
267 {
268         unsigned long flags;
269
270         spin_lock_irqsave(&blkg->stats_lock, flags);
271         BUG_ON(blkio_blkg_idling(&blkg->stats));
272         blkg->stats.start_idle_time = sched_clock();
273         blkio_mark_blkg_idling(&blkg->stats);
274         spin_unlock_irqrestore(&blkg->stats_lock, flags);
275 }
276 EXPORT_SYMBOL_GPL(blkiocg_update_set_idle_time_stats);
277
278 void blkiocg_update_idle_time_stats(struct blkio_group *blkg)
279 {
280         unsigned long flags;
281         unsigned long long now;
282         struct blkio_group_stats *stats;
283
284         spin_lock_irqsave(&blkg->stats_lock, flags);
285         stats = &blkg->stats;
286         if (blkio_blkg_idling(stats)) {
287                 now = sched_clock();
288                 if (time_after64(now, stats->start_idle_time))
289                         stats->idle_time += now - stats->start_idle_time;
290                 blkio_clear_blkg_idling(stats);
291         }
292         spin_unlock_irqrestore(&blkg->stats_lock, flags);
293 }
294 EXPORT_SYMBOL_GPL(blkiocg_update_idle_time_stats);
295
296 void blkiocg_update_avg_queue_size_stats(struct blkio_group *blkg)
297 {
298         unsigned long flags;
299         struct blkio_group_stats *stats;
300
301         spin_lock_irqsave(&blkg->stats_lock, flags);
302         stats = &blkg->stats;
303         stats->avg_queue_size_sum +=
304                         stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] +
305                         stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE];
306         stats->avg_queue_size_samples++;
307         blkio_update_group_wait_time(stats);
308         spin_unlock_irqrestore(&blkg->stats_lock, flags);
309 }
310 EXPORT_SYMBOL_GPL(blkiocg_update_avg_queue_size_stats);
311
312 void blkiocg_set_start_empty_time(struct blkio_group *blkg)
313 {
314         unsigned long flags;
315         struct blkio_group_stats *stats;
316
317         spin_lock_irqsave(&blkg->stats_lock, flags);
318         stats = &blkg->stats;
319
320         if (stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] ||
321                         stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE]) {
322                 spin_unlock_irqrestore(&blkg->stats_lock, flags);
323                 return;
324         }
325
326         /*
327          * group is already marked empty. This can happen if cfqq got new
328          * request in parent group and moved to this group while being added
329          * to service tree. Just ignore the event and move on.
330          */
331         if(blkio_blkg_empty(stats)) {
332                 spin_unlock_irqrestore(&blkg->stats_lock, flags);
333                 return;
334         }
335
336         stats->start_empty_time = sched_clock();
337         blkio_mark_blkg_empty(stats);
338         spin_unlock_irqrestore(&blkg->stats_lock, flags);
339 }
340 EXPORT_SYMBOL_GPL(blkiocg_set_start_empty_time);
341
342 void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
343                         unsigned long dequeue)
344 {
345         blkg->stats.dequeue += dequeue;
346 }
347 EXPORT_SYMBOL_GPL(blkiocg_update_dequeue_stats);
348 #else
349 static inline void blkio_set_start_group_wait_time(struct blkio_group *blkg,
350                                         struct blkio_group *curr_blkg) {}
351 static inline void blkio_end_empty_time(struct blkio_group_stats *stats) {}
352 #endif
353
354 void blkiocg_update_io_add_stats(struct blkio_group *blkg,
355                         struct blkio_group *curr_blkg, bool direction,
356                         bool sync)
357 {
358         unsigned long flags;
359
360         spin_lock_irqsave(&blkg->stats_lock, flags);
361         blkio_add_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED], 1, direction,
362                         sync);
363         blkio_end_empty_time(&blkg->stats);
364         blkio_set_start_group_wait_time(blkg, curr_blkg);
365         spin_unlock_irqrestore(&blkg->stats_lock, flags);
366 }
367 EXPORT_SYMBOL_GPL(blkiocg_update_io_add_stats);
368
369 void blkiocg_update_io_remove_stats(struct blkio_group *blkg,
370                                                 bool direction, bool sync)
371 {
372         unsigned long flags;
373
374         spin_lock_irqsave(&blkg->stats_lock, flags);
375         blkio_check_and_dec_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED],
376                                         direction, sync);
377         spin_unlock_irqrestore(&blkg->stats_lock, flags);
378 }
379 EXPORT_SYMBOL_GPL(blkiocg_update_io_remove_stats);
380
381 void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time,
382                                 unsigned long unaccounted_time)
383 {
384         unsigned long flags;
385
386         spin_lock_irqsave(&blkg->stats_lock, flags);
387         blkg->stats.time += time;
388 #ifdef CONFIG_DEBUG_BLK_CGROUP
389         blkg->stats.unaccounted_time += unaccounted_time;
390 #endif
391         spin_unlock_irqrestore(&blkg->stats_lock, flags);
392 }
393 EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);
394
395 void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
396                                 uint64_t bytes, bool direction, bool sync)
397 {
398         struct blkio_group_stats *stats;
399         unsigned long flags;
400
401         spin_lock_irqsave(&blkg->stats_lock, flags);
402         stats = &blkg->stats;
403         stats->sectors += bytes >> 9;
404         blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICED], 1, direction,
405                         sync);
406         blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_BYTES], bytes,
407                         direction, sync);
408         spin_unlock_irqrestore(&blkg->stats_lock, flags);
409 }
410 EXPORT_SYMBOL_GPL(blkiocg_update_dispatch_stats);
411
412 void blkiocg_update_completion_stats(struct blkio_group *blkg,
413         uint64_t start_time, uint64_t io_start_time, bool direction, bool sync)
414 {
415         struct blkio_group_stats *stats;
416         unsigned long flags;
417         unsigned long long now = sched_clock();
418
419         spin_lock_irqsave(&blkg->stats_lock, flags);
420         stats = &blkg->stats;
421         if (time_after64(now, io_start_time))
422                 blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_TIME],
423                                 now - io_start_time, direction, sync);
424         if (time_after64(io_start_time, start_time))
425                 blkio_add_stat(stats->stat_arr[BLKIO_STAT_WAIT_TIME],
426                                 io_start_time - start_time, direction, sync);
427         spin_unlock_irqrestore(&blkg->stats_lock, flags);
428 }
429 EXPORT_SYMBOL_GPL(blkiocg_update_completion_stats);
430
431 void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction,
432                                         bool sync)
433 {
434         unsigned long flags;
435
436         spin_lock_irqsave(&blkg->stats_lock, flags);
437         blkio_add_stat(blkg->stats.stat_arr[BLKIO_STAT_MERGED], 1, direction,
438                         sync);
439         spin_unlock_irqrestore(&blkg->stats_lock, flags);
440 }
441 EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats);
442
443 void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
444                 struct blkio_group *blkg, void *key, dev_t dev,
445                 enum blkio_policy_id plid)
446 {
447         unsigned long flags;
448
449         spin_lock_irqsave(&blkcg->lock, flags);
450         spin_lock_init(&blkg->stats_lock);
451         rcu_assign_pointer(blkg->key, key);
452         blkg->blkcg_id = css_id(&blkcg->css);
453         hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
454         blkg->plid = plid;
455         spin_unlock_irqrestore(&blkcg->lock, flags);
456         /* Need to take css reference ? */
457         cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
458         blkg->dev = dev;
459 }
460 EXPORT_SYMBOL_GPL(blkiocg_add_blkio_group);
461
462 static void __blkiocg_del_blkio_group(struct blkio_group *blkg)
463 {
464         hlist_del_init_rcu(&blkg->blkcg_node);
465         blkg->blkcg_id = 0;
466 }
467
468 /*
469  * returns 0 if blkio_group was still on cgroup list. Otherwise returns 1
470  * indicating that blk_group was unhashed by the time we got to it.
471  */
472 int blkiocg_del_blkio_group(struct blkio_group *blkg)
473 {
474         struct blkio_cgroup *blkcg;
475         unsigned long flags;
476         struct cgroup_subsys_state *css;
477         int ret = 1;
478
479         rcu_read_lock();
480         css = css_lookup(&blkio_subsys, blkg->blkcg_id);
481         if (css) {
482                 blkcg = container_of(css, struct blkio_cgroup, css);
483                 spin_lock_irqsave(&blkcg->lock, flags);
484                 if (!hlist_unhashed(&blkg->blkcg_node)) {
485                         __blkiocg_del_blkio_group(blkg);
486                         ret = 0;
487                 }
488                 spin_unlock_irqrestore(&blkcg->lock, flags);
489         }
490
491         rcu_read_unlock();
492         return ret;
493 }
494 EXPORT_SYMBOL_GPL(blkiocg_del_blkio_group);
495
496 /* called under rcu_read_lock(). */
497 struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key)
498 {
499         struct blkio_group *blkg;
500         struct hlist_node *n;
501         void *__key;
502
503         hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
504                 __key = blkg->key;
505                 if (__key == key)
506                         return blkg;
507         }
508
509         return NULL;
510 }
511 EXPORT_SYMBOL_GPL(blkiocg_lookup_group);
512
513 static int
514 blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
515 {
516         struct blkio_cgroup *blkcg;
517         struct blkio_group *blkg;
518         struct blkio_group_stats *stats;
519         struct hlist_node *n;
520         uint64_t queued[BLKIO_STAT_TOTAL];
521         int i;
522 #ifdef CONFIG_DEBUG_BLK_CGROUP
523         bool idling, waiting, empty;
524         unsigned long long now = sched_clock();
525 #endif
526
527         blkcg = cgroup_to_blkio_cgroup(cgroup);
528         spin_lock_irq(&blkcg->lock);
529         hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
530                 spin_lock(&blkg->stats_lock);
531                 stats = &blkg->stats;
532 #ifdef CONFIG_DEBUG_BLK_CGROUP
533                 idling = blkio_blkg_idling(stats);
534                 waiting = blkio_blkg_waiting(stats);
535                 empty = blkio_blkg_empty(stats);
536 #endif
537                 for (i = 0; i < BLKIO_STAT_TOTAL; i++)
538                         queued[i] = stats->stat_arr[BLKIO_STAT_QUEUED][i];
539                 memset(stats, 0, sizeof(struct blkio_group_stats));
540                 for (i = 0; i < BLKIO_STAT_TOTAL; i++)
541                         stats->stat_arr[BLKIO_STAT_QUEUED][i] = queued[i];
542 #ifdef CONFIG_DEBUG_BLK_CGROUP
543                 if (idling) {
544                         blkio_mark_blkg_idling(stats);
545                         stats->start_idle_time = now;
546                 }
547                 if (waiting) {
548                         blkio_mark_blkg_waiting(stats);
549                         stats->start_group_wait_time = now;
550                 }
551                 if (empty) {
552                         blkio_mark_blkg_empty(stats);
553                         stats->start_empty_time = now;
554                 }
555 #endif
556                 spin_unlock(&blkg->stats_lock);
557         }
558         spin_unlock_irq(&blkcg->lock);
559         return 0;
560 }
561
562 static void blkio_get_key_name(enum stat_sub_type type, dev_t dev, char *str,
563                                 int chars_left, bool diskname_only)
564 {
565         snprintf(str, chars_left, "%d:%d", MAJOR(dev), MINOR(dev));
566         chars_left -= strlen(str);
567         if (chars_left <= 0) {
568                 printk(KERN_WARNING
569                         "Possibly incorrect cgroup stat display format");
570                 return;
571         }
572         if (diskname_only)
573                 return;
574         switch (type) {
575         case BLKIO_STAT_READ:
576                 strlcat(str, " Read", chars_left);
577                 break;
578         case BLKIO_STAT_WRITE:
579                 strlcat(str, " Write", chars_left);
580                 break;
581         case BLKIO_STAT_SYNC:
582                 strlcat(str, " Sync", chars_left);
583                 break;
584         case BLKIO_STAT_ASYNC:
585                 strlcat(str, " Async", chars_left);
586                 break;
587         case BLKIO_STAT_TOTAL:
588                 strlcat(str, " Total", chars_left);
589                 break;
590         default:
591                 strlcat(str, " Invalid", chars_left);
592         }
593 }
594
595 static uint64_t blkio_fill_stat(char *str, int chars_left, uint64_t val,
596                                 struct cgroup_map_cb *cb, dev_t dev)
597 {
598         blkio_get_key_name(0, dev, str, chars_left, true);
599         cb->fill(cb, str, val);
600         return val;
601 }
602
603 /* This should be called with blkg->stats_lock held */
604 static uint64_t blkio_get_stat(struct blkio_group *blkg,
605                 struct cgroup_map_cb *cb, dev_t dev, enum stat_type type)
606 {
607         uint64_t disk_total;
608         char key_str[MAX_KEY_LEN];
609         enum stat_sub_type sub_type;
610
611         if (type == BLKIO_STAT_TIME)
612                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
613                                         blkg->stats.time, cb, dev);
614         if (type == BLKIO_STAT_SECTORS)
615                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
616                                         blkg->stats.sectors, cb, dev);
617 #ifdef CONFIG_DEBUG_BLK_CGROUP
618         if (type == BLKIO_STAT_UNACCOUNTED_TIME)
619                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
620                                         blkg->stats.unaccounted_time, cb, dev);
621         if (type == BLKIO_STAT_AVG_QUEUE_SIZE) {
622                 uint64_t sum = blkg->stats.avg_queue_size_sum;
623                 uint64_t samples = blkg->stats.avg_queue_size_samples;
624                 if (samples)
625                         do_div(sum, samples);
626                 else
627                         sum = 0;
628                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, sum, cb, dev);
629         }
630         if (type == BLKIO_STAT_GROUP_WAIT_TIME)
631                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
632                                         blkg->stats.group_wait_time, cb, dev);
633         if (type == BLKIO_STAT_IDLE_TIME)
634                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
635                                         blkg->stats.idle_time, cb, dev);
636         if (type == BLKIO_STAT_EMPTY_TIME)
637                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
638                                         blkg->stats.empty_time, cb, dev);
639         if (type == BLKIO_STAT_DEQUEUE)
640                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
641                                         blkg->stats.dequeue, cb, dev);
642 #endif
643
644         for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL;
645                         sub_type++) {
646                 blkio_get_key_name(sub_type, dev, key_str, MAX_KEY_LEN, false);
647                 cb->fill(cb, key_str, blkg->stats.stat_arr[type][sub_type]);
648         }
649         disk_total = blkg->stats.stat_arr[type][BLKIO_STAT_READ] +
650                         blkg->stats.stat_arr[type][BLKIO_STAT_WRITE];
651         blkio_get_key_name(BLKIO_STAT_TOTAL, dev, key_str, MAX_KEY_LEN, false);
652         cb->fill(cb, key_str, disk_total);
653         return disk_total;
654 }
655
656 static int blkio_check_dev_num(dev_t dev)
657 {
658         int part = 0;
659         struct gendisk *disk;
660
661         disk = get_gendisk(dev, &part);
662         if (!disk || part)
663                 return -ENODEV;
664
665         return 0;
666 }
667
668 static int blkio_policy_parse_and_set(char *buf,
669         struct blkio_policy_node *newpn, enum blkio_policy_id plid, int fileid)
670 {
671         char *s[4], *p, *major_s = NULL, *minor_s = NULL;
672         int ret;
673         unsigned long major, minor, temp;
674         int i = 0;
675         dev_t dev;
676         u64 bps, iops;
677
678         memset(s, 0, sizeof(s));
679
680         while ((p = strsep(&buf, " ")) != NULL) {
681                 if (!*p)
682                         continue;
683
684                 s[i++] = p;
685
686                 /* Prevent from inputing too many things */
687                 if (i == 3)
688                         break;
689         }
690
691         if (i != 2)
692                 return -EINVAL;
693
694         p = strsep(&s[0], ":");
695         if (p != NULL)
696                 major_s = p;
697         else
698                 return -EINVAL;
699
700         minor_s = s[0];
701         if (!minor_s)
702                 return -EINVAL;
703
704         ret = strict_strtoul(major_s, 10, &major);
705         if (ret)
706                 return -EINVAL;
707
708         ret = strict_strtoul(minor_s, 10, &minor);
709         if (ret)
710                 return -EINVAL;
711
712         dev = MKDEV(major, minor);
713
714         ret = blkio_check_dev_num(dev);
715         if (ret)
716                 return ret;
717
718         newpn->dev = dev;
719
720         if (s[1] == NULL)
721                 return -EINVAL;
722
723         switch (plid) {
724         case BLKIO_POLICY_PROP:
725                 ret = strict_strtoul(s[1], 10, &temp);
726                 if (ret || (temp < BLKIO_WEIGHT_MIN && temp > 0) ||
727                         temp > BLKIO_WEIGHT_MAX)
728                         return -EINVAL;
729
730                 newpn->plid = plid;
731                 newpn->fileid = fileid;
732                 newpn->val.weight = temp;
733                 break;
734         case BLKIO_POLICY_THROTL:
735                 switch(fileid) {
736                 case BLKIO_THROTL_read_bps_device:
737                 case BLKIO_THROTL_write_bps_device:
738                         ret = strict_strtoull(s[1], 10, &bps);
739                         if (ret)
740                                 return -EINVAL;
741
742                         newpn->plid = plid;
743                         newpn->fileid = fileid;
744                         newpn->val.bps = bps;
745                         break;
746                 case BLKIO_THROTL_read_iops_device:
747                 case BLKIO_THROTL_write_iops_device:
748                         ret = strict_strtoull(s[1], 10, &iops);
749                         if (ret)
750                                 return -EINVAL;
751
752                         if (iops > THROTL_IOPS_MAX)
753                                 return -EINVAL;
754
755                         newpn->plid = plid;
756                         newpn->fileid = fileid;
757                         newpn->val.iops = (unsigned int)iops;
758                         break;
759                 }
760                 break;
761         default:
762                 BUG();
763         }
764
765         return 0;
766 }
767
768 unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
769                               dev_t dev)
770 {
771         struct blkio_policy_node *pn;
772
773         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_PROP,
774                                 BLKIO_PROP_weight_device);
775         if (pn)
776                 return pn->val.weight;
777         else
778                 return blkcg->weight;
779 }
780 EXPORT_SYMBOL_GPL(blkcg_get_weight);
781
782 uint64_t blkcg_get_read_bps(struct blkio_cgroup *blkcg, dev_t dev)
783 {
784         struct blkio_policy_node *pn;
785
786         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
787                                 BLKIO_THROTL_read_bps_device);
788         if (pn)
789                 return pn->val.bps;
790         else
791                 return -1;
792 }
793
794 uint64_t blkcg_get_write_bps(struct blkio_cgroup *blkcg, dev_t dev)
795 {
796         struct blkio_policy_node *pn;
797         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
798                                 BLKIO_THROTL_write_bps_device);
799         if (pn)
800                 return pn->val.bps;
801         else
802                 return -1;
803 }
804
805 unsigned int blkcg_get_read_iops(struct blkio_cgroup *blkcg, dev_t dev)
806 {
807         struct blkio_policy_node *pn;
808
809         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
810                                 BLKIO_THROTL_read_iops_device);
811         if (pn)
812                 return pn->val.iops;
813         else
814                 return -1;
815 }
816
817 unsigned int blkcg_get_write_iops(struct blkio_cgroup *blkcg, dev_t dev)
818 {
819         struct blkio_policy_node *pn;
820         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
821                                 BLKIO_THROTL_write_iops_device);
822         if (pn)
823                 return pn->val.iops;
824         else
825                 return -1;
826 }
827
828 /* Checks whether user asked for deleting a policy rule */
829 static bool blkio_delete_rule_command(struct blkio_policy_node *pn)
830 {
831         switch(pn->plid) {
832         case BLKIO_POLICY_PROP:
833                 if (pn->val.weight == 0)
834                         return 1;
835                 break;
836         case BLKIO_POLICY_THROTL:
837                 switch(pn->fileid) {
838                 case BLKIO_THROTL_read_bps_device:
839                 case BLKIO_THROTL_write_bps_device:
840                         if (pn->val.bps == 0)
841                                 return 1;
842                         break;
843                 case BLKIO_THROTL_read_iops_device:
844                 case BLKIO_THROTL_write_iops_device:
845                         if (pn->val.iops == 0)
846                                 return 1;
847                 }
848                 break;
849         default:
850                 BUG();
851         }
852
853         return 0;
854 }
855
856 static void blkio_update_policy_rule(struct blkio_policy_node *oldpn,
857                                         struct blkio_policy_node *newpn)
858 {
859         switch(oldpn->plid) {
860         case BLKIO_POLICY_PROP:
861                 oldpn->val.weight = newpn->val.weight;
862                 break;
863         case BLKIO_POLICY_THROTL:
864                 switch(newpn->fileid) {
865                 case BLKIO_THROTL_read_bps_device:
866                 case BLKIO_THROTL_write_bps_device:
867                         oldpn->val.bps = newpn->val.bps;
868                         break;
869                 case BLKIO_THROTL_read_iops_device:
870                 case BLKIO_THROTL_write_iops_device:
871                         oldpn->val.iops = newpn->val.iops;
872                 }
873                 break;
874         default:
875                 BUG();
876         }
877 }
878
879 /*
880  * Some rules/values in blkg have changed. Propagate those to respective
881  * policies.
882  */
883 static void blkio_update_blkg_policy(struct blkio_cgroup *blkcg,
884                 struct blkio_group *blkg, struct blkio_policy_node *pn)
885 {
886         unsigned int weight, iops;
887         u64 bps;
888
889         switch(pn->plid) {
890         case BLKIO_POLICY_PROP:
891                 weight = pn->val.weight ? pn->val.weight :
892                                 blkcg->weight;
893                 blkio_update_group_weight(blkg, weight);
894                 break;
895         case BLKIO_POLICY_THROTL:
896                 switch(pn->fileid) {
897                 case BLKIO_THROTL_read_bps_device:
898                 case BLKIO_THROTL_write_bps_device:
899                         bps = pn->val.bps ? pn->val.bps : (-1);
900                         blkio_update_group_bps(blkg, bps, pn->fileid);
901                         break;
902                 case BLKIO_THROTL_read_iops_device:
903                 case BLKIO_THROTL_write_iops_device:
904                         iops = pn->val.iops ? pn->val.iops : (-1);
905                         blkio_update_group_iops(blkg, iops, pn->fileid);
906                         break;
907                 }
908                 break;
909         default:
910                 BUG();
911         }
912 }
913
914 /*
915  * A policy node rule has been updated. Propagate this update to all the
916  * block groups which might be affected by this update.
917  */
918 static void blkio_update_policy_node_blkg(struct blkio_cgroup *blkcg,
919                                 struct blkio_policy_node *pn)
920 {
921         struct blkio_group *blkg;
922         struct hlist_node *n;
923
924         spin_lock(&blkio_list_lock);
925         spin_lock_irq(&blkcg->lock);
926
927         hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
928                 if (pn->dev != blkg->dev || pn->plid != blkg->plid)
929                         continue;
930                 blkio_update_blkg_policy(blkcg, blkg, pn);
931         }
932
933         spin_unlock_irq(&blkcg->lock);
934         spin_unlock(&blkio_list_lock);
935 }
936
937 static int blkiocg_file_write(struct cgroup *cgrp, struct cftype *cft,
938                                        const char *buffer)
939 {
940         int ret = 0;
941         char *buf;
942         struct blkio_policy_node *newpn, *pn;
943         struct blkio_cgroup *blkcg;
944         int keep_newpn = 0;
945         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
946         int fileid = BLKIOFILE_ATTR(cft->private);
947
948         buf = kstrdup(buffer, GFP_KERNEL);
949         if (!buf)
950                 return -ENOMEM;
951
952         newpn = kzalloc(sizeof(*newpn), GFP_KERNEL);
953         if (!newpn) {
954                 ret = -ENOMEM;
955                 goto free_buf;
956         }
957
958         ret = blkio_policy_parse_and_set(buf, newpn, plid, fileid);
959         if (ret)
960                 goto free_newpn;
961
962         blkcg = cgroup_to_blkio_cgroup(cgrp);
963
964         spin_lock_irq(&blkcg->lock);
965
966         pn = blkio_policy_search_node(blkcg, newpn->dev, plid, fileid);
967         if (!pn) {
968                 if (!blkio_delete_rule_command(newpn)) {
969                         blkio_policy_insert_node(blkcg, newpn);
970                         keep_newpn = 1;
971                 }
972                 spin_unlock_irq(&blkcg->lock);
973                 goto update_io_group;
974         }
975
976         if (blkio_delete_rule_command(newpn)) {
977                 blkio_policy_delete_node(pn);
978                 spin_unlock_irq(&blkcg->lock);
979                 goto update_io_group;
980         }
981         spin_unlock_irq(&blkcg->lock);
982
983         blkio_update_policy_rule(pn, newpn);
984
985 update_io_group:
986         blkio_update_policy_node_blkg(blkcg, newpn);
987
988 free_newpn:
989         if (!keep_newpn)
990                 kfree(newpn);
991 free_buf:
992         kfree(buf);
993         return ret;
994 }
995
996 static void
997 blkio_print_policy_node(struct seq_file *m, struct blkio_policy_node *pn)
998 {
999         switch(pn->plid) {
1000                 case BLKIO_POLICY_PROP:
1001                         if (pn->fileid == BLKIO_PROP_weight_device)
1002                                 seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
1003                                         MINOR(pn->dev), pn->val.weight);
1004                         break;
1005                 case BLKIO_POLICY_THROTL:
1006                         switch(pn->fileid) {
1007                         case BLKIO_THROTL_read_bps_device:
1008                         case BLKIO_THROTL_write_bps_device:
1009                                 seq_printf(m, "%u:%u\t%llu\n", MAJOR(pn->dev),
1010                                         MINOR(pn->dev), pn->val.bps);
1011                                 break;
1012                         case BLKIO_THROTL_read_iops_device:
1013                         case BLKIO_THROTL_write_iops_device:
1014                                 seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
1015                                         MINOR(pn->dev), pn->val.iops);
1016                                 break;
1017                         }
1018                         break;
1019                 default:
1020                         BUG();
1021         }
1022 }
1023
1024 /* cgroup files which read their data from policy nodes end up here */
1025 static void blkio_read_policy_node_files(struct cftype *cft,
1026                         struct blkio_cgroup *blkcg, struct seq_file *m)
1027 {
1028         struct blkio_policy_node *pn;
1029
1030         if (!list_empty(&blkcg->policy_list)) {
1031                 spin_lock_irq(&blkcg->lock);
1032                 list_for_each_entry(pn, &blkcg->policy_list, node) {
1033                         if (!pn_matches_cftype(cft, pn))
1034                                 continue;
1035                         blkio_print_policy_node(m, pn);
1036                 }
1037                 spin_unlock_irq(&blkcg->lock);
1038         }
1039 }
1040
1041 static int blkiocg_file_read(struct cgroup *cgrp, struct cftype *cft,
1042                                 struct seq_file *m)
1043 {
1044         struct blkio_cgroup *blkcg;
1045         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1046         int name = BLKIOFILE_ATTR(cft->private);
1047
1048         blkcg = cgroup_to_blkio_cgroup(cgrp);
1049
1050         switch(plid) {
1051         case BLKIO_POLICY_PROP:
1052                 switch(name) {
1053                 case BLKIO_PROP_weight_device:
1054                         blkio_read_policy_node_files(cft, blkcg, m);
1055                         return 0;
1056                 default:
1057                         BUG();
1058                 }
1059                 break;
1060         case BLKIO_POLICY_THROTL:
1061                 switch(name){
1062                 case BLKIO_THROTL_read_bps_device:
1063                 case BLKIO_THROTL_write_bps_device:
1064                 case BLKIO_THROTL_read_iops_device:
1065                 case BLKIO_THROTL_write_iops_device:
1066                         blkio_read_policy_node_files(cft, blkcg, m);
1067                         return 0;
1068                 default:
1069                         BUG();
1070                 }
1071                 break;
1072         default:
1073                 BUG();
1074         }
1075
1076         return 0;
1077 }
1078
1079 static int blkio_read_blkg_stats(struct blkio_cgroup *blkcg,
1080                 struct cftype *cft, struct cgroup_map_cb *cb, enum stat_type type,
1081                 bool show_total)
1082 {
1083         struct blkio_group *blkg;
1084         struct hlist_node *n;
1085         uint64_t cgroup_total = 0;
1086
1087         rcu_read_lock();
1088         hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
1089                 if (blkg->dev) {
1090                         if (!cftype_blkg_same_policy(cft, blkg))
1091                                 continue;
1092                         spin_lock_irq(&blkg->stats_lock);
1093                         cgroup_total += blkio_get_stat(blkg, cb, blkg->dev,
1094                                                 type);
1095                         spin_unlock_irq(&blkg->stats_lock);
1096                 }
1097         }
1098         if (show_total)
1099                 cb->fill(cb, "Total", cgroup_total);
1100         rcu_read_unlock();
1101         return 0;
1102 }
1103
1104 /* All map kind of cgroup file get serviced by this function */
1105 static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft,
1106                                 struct cgroup_map_cb *cb)
1107 {
1108         struct blkio_cgroup *blkcg;
1109         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1110         int name = BLKIOFILE_ATTR(cft->private);
1111
1112         blkcg = cgroup_to_blkio_cgroup(cgrp);
1113
1114         switch(plid) {
1115         case BLKIO_POLICY_PROP:
1116                 switch(name) {
1117                 case BLKIO_PROP_time:
1118                         return blkio_read_blkg_stats(blkcg, cft, cb,
1119                                                 BLKIO_STAT_TIME, 0);
1120                 case BLKIO_PROP_sectors:
1121                         return blkio_read_blkg_stats(blkcg, cft, cb,
1122                                                 BLKIO_STAT_SECTORS, 0);
1123                 case BLKIO_PROP_io_service_bytes:
1124                         return blkio_read_blkg_stats(blkcg, cft, cb,
1125                                                 BLKIO_STAT_SERVICE_BYTES, 1);
1126                 case BLKIO_PROP_io_serviced:
1127                         return blkio_read_blkg_stats(blkcg, cft, cb,
1128                                                 BLKIO_STAT_SERVICED, 1);
1129                 case BLKIO_PROP_io_service_time:
1130                         return blkio_read_blkg_stats(blkcg, cft, cb,
1131                                                 BLKIO_STAT_SERVICE_TIME, 1);
1132                 case BLKIO_PROP_io_wait_time:
1133                         return blkio_read_blkg_stats(blkcg, cft, cb,
1134                                                 BLKIO_STAT_WAIT_TIME, 1);
1135                 case BLKIO_PROP_io_merged:
1136                         return blkio_read_blkg_stats(blkcg, cft, cb,
1137                                                 BLKIO_STAT_MERGED, 1);
1138                 case BLKIO_PROP_io_queued:
1139                         return blkio_read_blkg_stats(blkcg, cft, cb,
1140                                                 BLKIO_STAT_QUEUED, 1);
1141 #ifdef CONFIG_DEBUG_BLK_CGROUP
1142                 case BLKIO_PROP_unaccounted_time:
1143                         return blkio_read_blkg_stats(blkcg, cft, cb,
1144                                                 BLKIO_STAT_UNACCOUNTED_TIME, 0);
1145                 case BLKIO_PROP_dequeue:
1146                         return blkio_read_blkg_stats(blkcg, cft, cb,
1147                                                 BLKIO_STAT_DEQUEUE, 0);
1148                 case BLKIO_PROP_avg_queue_size:
1149                         return blkio_read_blkg_stats(blkcg, cft, cb,
1150                                                 BLKIO_STAT_AVG_QUEUE_SIZE, 0);
1151                 case BLKIO_PROP_group_wait_time:
1152                         return blkio_read_blkg_stats(blkcg, cft, cb,
1153                                                 BLKIO_STAT_GROUP_WAIT_TIME, 0);
1154                 case BLKIO_PROP_idle_time:
1155                         return blkio_read_blkg_stats(blkcg, cft, cb,
1156                                                 BLKIO_STAT_IDLE_TIME, 0);
1157                 case BLKIO_PROP_empty_time:
1158                         return blkio_read_blkg_stats(blkcg, cft, cb,
1159                                                 BLKIO_STAT_EMPTY_TIME, 0);
1160 #endif
1161                 default:
1162                         BUG();
1163                 }
1164                 break;
1165         case BLKIO_POLICY_THROTL:
1166                 switch(name){
1167                 case BLKIO_THROTL_io_service_bytes:
1168                         return blkio_read_blkg_stats(blkcg, cft, cb,
1169                                                 BLKIO_STAT_SERVICE_BYTES, 1);
1170                 case BLKIO_THROTL_io_serviced:
1171                         return blkio_read_blkg_stats(blkcg, cft, cb,
1172                                                 BLKIO_STAT_SERVICED, 1);
1173                 default:
1174                         BUG();
1175                 }
1176                 break;
1177         default:
1178                 BUG();
1179         }
1180
1181         return 0;
1182 }
1183
1184 static int blkio_weight_write(struct blkio_cgroup *blkcg, u64 val)
1185 {
1186         struct blkio_group *blkg;
1187         struct hlist_node *n;
1188         struct blkio_policy_node *pn;
1189
1190         if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
1191                 return -EINVAL;
1192
1193         spin_lock(&blkio_list_lock);
1194         spin_lock_irq(&blkcg->lock);
1195         blkcg->weight = (unsigned int)val;
1196
1197         hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
1198                 pn = blkio_policy_search_node(blkcg, blkg->dev,
1199                                 BLKIO_POLICY_PROP, BLKIO_PROP_weight_device);
1200                 if (pn)
1201                         continue;
1202
1203                 blkio_update_group_weight(blkg, blkcg->weight);
1204         }
1205         spin_unlock_irq(&blkcg->lock);
1206         spin_unlock(&blkio_list_lock);
1207         return 0;
1208 }
1209
1210 static u64 blkiocg_file_read_u64 (struct cgroup *cgrp, struct cftype *cft) {
1211         struct blkio_cgroup *blkcg;
1212         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1213         int name = BLKIOFILE_ATTR(cft->private);
1214
1215         blkcg = cgroup_to_blkio_cgroup(cgrp);
1216
1217         switch(plid) {
1218         case BLKIO_POLICY_PROP:
1219                 switch(name) {
1220                 case BLKIO_PROP_weight:
1221                         return (u64)blkcg->weight;
1222                 }
1223                 break;
1224         default:
1225                 BUG();
1226         }
1227         return 0;
1228 }
1229
1230 static int
1231 blkiocg_file_write_u64(struct cgroup *cgrp, struct cftype *cft, u64 val)
1232 {
1233         struct blkio_cgroup *blkcg;
1234         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1235         int name = BLKIOFILE_ATTR(cft->private);
1236
1237         blkcg = cgroup_to_blkio_cgroup(cgrp);
1238
1239         switch(plid) {
1240         case BLKIO_POLICY_PROP:
1241                 switch(name) {
1242                 case BLKIO_PROP_weight:
1243                         return blkio_weight_write(blkcg, val);
1244                 }
1245                 break;
1246         default:
1247                 BUG();
1248         }
1249
1250         return 0;
1251 }
1252
1253 struct cftype blkio_files[] = {
1254         {
1255                 .name = "weight_device",
1256                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1257                                 BLKIO_PROP_weight_device),
1258                 .read_seq_string = blkiocg_file_read,
1259                 .write_string = blkiocg_file_write,
1260                 .max_write_len = 256,
1261         },
1262         {
1263                 .name = "weight",
1264                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1265                                 BLKIO_PROP_weight),
1266                 .read_u64 = blkiocg_file_read_u64,
1267                 .write_u64 = blkiocg_file_write_u64,
1268         },
1269         {
1270                 .name = "time",
1271                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1272                                 BLKIO_PROP_time),
1273                 .read_map = blkiocg_file_read_map,
1274         },
1275         {
1276                 .name = "sectors",
1277                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1278                                 BLKIO_PROP_sectors),
1279                 .read_map = blkiocg_file_read_map,
1280         },
1281         {
1282                 .name = "io_service_bytes",
1283                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1284                                 BLKIO_PROP_io_service_bytes),
1285                 .read_map = blkiocg_file_read_map,
1286         },
1287         {
1288                 .name = "io_serviced",
1289                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1290                                 BLKIO_PROP_io_serviced),
1291                 .read_map = blkiocg_file_read_map,
1292         },
1293         {
1294                 .name = "io_service_time",
1295                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1296                                 BLKIO_PROP_io_service_time),
1297                 .read_map = blkiocg_file_read_map,
1298         },
1299         {
1300                 .name = "io_wait_time",
1301                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1302                                 BLKIO_PROP_io_wait_time),
1303                 .read_map = blkiocg_file_read_map,
1304         },
1305         {
1306                 .name = "io_merged",
1307                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1308                                 BLKIO_PROP_io_merged),
1309                 .read_map = blkiocg_file_read_map,
1310         },
1311         {
1312                 .name = "io_queued",
1313                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1314                                 BLKIO_PROP_io_queued),
1315                 .read_map = blkiocg_file_read_map,
1316         },
1317         {
1318                 .name = "reset_stats",
1319                 .write_u64 = blkiocg_reset_stats,
1320         },
1321 #ifdef CONFIG_BLK_DEV_THROTTLING
1322         {
1323                 .name = "throttle.read_bps_device",
1324                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1325                                 BLKIO_THROTL_read_bps_device),
1326                 .read_seq_string = blkiocg_file_read,
1327                 .write_string = blkiocg_file_write,
1328                 .max_write_len = 256,
1329         },
1330
1331         {
1332                 .name = "throttle.write_bps_device",
1333                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1334                                 BLKIO_THROTL_write_bps_device),
1335                 .read_seq_string = blkiocg_file_read,
1336                 .write_string = blkiocg_file_write,
1337                 .max_write_len = 256,
1338         },
1339
1340         {
1341                 .name = "throttle.read_iops_device",
1342                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1343                                 BLKIO_THROTL_read_iops_device),
1344                 .read_seq_string = blkiocg_file_read,
1345                 .write_string = blkiocg_file_write,
1346                 .max_write_len = 256,
1347         },
1348
1349         {
1350                 .name = "throttle.write_iops_device",
1351                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1352                                 BLKIO_THROTL_write_iops_device),
1353                 .read_seq_string = blkiocg_file_read,
1354                 .write_string = blkiocg_file_write,
1355                 .max_write_len = 256,
1356         },
1357         {
1358                 .name = "throttle.io_service_bytes",
1359                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1360                                 BLKIO_THROTL_io_service_bytes),
1361                 .read_map = blkiocg_file_read_map,
1362         },
1363         {
1364                 .name = "throttle.io_serviced",
1365                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1366                                 BLKIO_THROTL_io_serviced),
1367                 .read_map = blkiocg_file_read_map,
1368         },
1369 #endif /* CONFIG_BLK_DEV_THROTTLING */
1370
1371 #ifdef CONFIG_DEBUG_BLK_CGROUP
1372         {
1373                 .name = "avg_queue_size",
1374                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1375                                 BLKIO_PROP_avg_queue_size),
1376                 .read_map = blkiocg_file_read_map,
1377         },
1378         {
1379                 .name = "group_wait_time",
1380                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1381                                 BLKIO_PROP_group_wait_time),
1382                 .read_map = blkiocg_file_read_map,
1383         },
1384         {
1385                 .name = "idle_time",
1386                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1387                                 BLKIO_PROP_idle_time),
1388                 .read_map = blkiocg_file_read_map,
1389         },
1390         {
1391                 .name = "empty_time",
1392                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1393                                 BLKIO_PROP_empty_time),
1394                 .read_map = blkiocg_file_read_map,
1395         },
1396         {
1397                 .name = "dequeue",
1398                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1399                                 BLKIO_PROP_dequeue),
1400                 .read_map = blkiocg_file_read_map,
1401         },
1402         {
1403                 .name = "unaccounted_time",
1404                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1405                                 BLKIO_PROP_unaccounted_time),
1406                 .read_map = blkiocg_file_read_map,
1407         },
1408 #endif
1409 };
1410
1411 static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1412 {
1413         return cgroup_add_files(cgroup, subsys, blkio_files,
1414                                 ARRAY_SIZE(blkio_files));
1415 }
1416
1417 static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1418 {
1419         struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
1420         unsigned long flags;
1421         struct blkio_group *blkg;
1422         void *key;
1423         struct blkio_policy_type *blkiop;
1424         struct blkio_policy_node *pn, *pntmp;
1425
1426         rcu_read_lock();
1427         do {
1428                 spin_lock_irqsave(&blkcg->lock, flags);
1429
1430                 if (hlist_empty(&blkcg->blkg_list)) {
1431                         spin_unlock_irqrestore(&blkcg->lock, flags);
1432                         break;
1433                 }
1434
1435                 blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group,
1436                                         blkcg_node);
1437                 key = rcu_dereference(blkg->key);
1438                 __blkiocg_del_blkio_group(blkg);
1439
1440                 spin_unlock_irqrestore(&blkcg->lock, flags);
1441
1442                 /*
1443                  * This blkio_group is being unlinked as associated cgroup is
1444                  * going away. Let all the IO controlling policies know about
1445                  * this event.
1446                  */
1447                 spin_lock(&blkio_list_lock);
1448                 list_for_each_entry(blkiop, &blkio_list, list) {
1449                         if (blkiop->plid != blkg->plid)
1450                                 continue;
1451                         blkiop->ops.blkio_unlink_group_fn(key, blkg);
1452                 }
1453                 spin_unlock(&blkio_list_lock);
1454         } while (1);
1455
1456         list_for_each_entry_safe(pn, pntmp, &blkcg->policy_list, node) {
1457                 blkio_policy_delete_node(pn);
1458                 kfree(pn);
1459         }
1460
1461         free_css_id(&blkio_subsys, &blkcg->css);
1462         rcu_read_unlock();
1463         if (blkcg != &blkio_root_cgroup)
1464                 kfree(blkcg);
1465 }
1466
1467 static struct cgroup_subsys_state *
1468 blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1469 {
1470         struct blkio_cgroup *blkcg;
1471         struct cgroup *parent = cgroup->parent;
1472
1473         if (!parent) {
1474                 blkcg = &blkio_root_cgroup;
1475                 goto done;
1476         }
1477
1478         blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
1479         if (!blkcg)
1480                 return ERR_PTR(-ENOMEM);
1481
1482         blkcg->weight = BLKIO_WEIGHT_DEFAULT;
1483 done:
1484         spin_lock_init(&blkcg->lock);
1485         INIT_HLIST_HEAD(&blkcg->blkg_list);
1486
1487         INIT_LIST_HEAD(&blkcg->policy_list);
1488         return &blkcg->css;
1489 }
1490
1491 /*
1492  * We cannot support shared io contexts, as we have no mean to support
1493  * two tasks with the same ioc in two different groups without major rework
1494  * of the main cic data structures.  For now we allow a task to change
1495  * its cgroup only if it's the only owner of its ioc.
1496  */
1497 static int blkiocg_can_attach(struct cgroup_subsys *subsys,
1498                                 struct cgroup *cgroup, struct task_struct *tsk,
1499                                 bool threadgroup)
1500 {
1501         struct io_context *ioc;
1502         int ret = 0;
1503
1504         /* task_lock() is needed to avoid races with exit_io_context() */
1505         task_lock(tsk);
1506         ioc = tsk->io_context;
1507         if (ioc && atomic_read(&ioc->nr_tasks) > 1)
1508                 ret = -EINVAL;
1509         task_unlock(tsk);
1510
1511         return ret;
1512 }
1513
1514 static void blkiocg_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup,
1515                                 struct cgroup *prev, struct task_struct *tsk,
1516                                 bool threadgroup)
1517 {
1518         struct io_context *ioc;
1519
1520         task_lock(tsk);
1521         ioc = tsk->io_context;
1522         if (ioc)
1523                 ioc->cgroup_changed = 1;
1524         task_unlock(tsk);
1525 }
1526
1527 void blkio_policy_register(struct blkio_policy_type *blkiop)
1528 {
1529         spin_lock(&blkio_list_lock);
1530         list_add_tail(&blkiop->list, &blkio_list);
1531         spin_unlock(&blkio_list_lock);
1532 }
1533 EXPORT_SYMBOL_GPL(blkio_policy_register);
1534
1535 void blkio_policy_unregister(struct blkio_policy_type *blkiop)
1536 {
1537         spin_lock(&blkio_list_lock);
1538         list_del_init(&blkiop->list);
1539         spin_unlock(&blkio_list_lock);
1540 }
1541 EXPORT_SYMBOL_GPL(blkio_policy_unregister);
1542
1543 static int __init init_cgroup_blkio(void)
1544 {
1545         return cgroup_load_subsys(&blkio_subsys);
1546 }
1547
1548 static void __exit exit_cgroup_blkio(void)
1549 {
1550         cgroup_unload_subsys(&blkio_subsys);
1551 }
1552
1553 module_init(init_cgroup_blkio);
1554 module_exit(exit_cgroup_blkio);
1555 MODULE_LICENSE("GPL");