Root/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
25static DEFINE_SPINLOCK(blkio_list_lock);
26static LIST_HEAD(blkio_list);
27
28struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
29EXPORT_SYMBOL_GPL(blkio_root_cgroup);
30
31static struct cgroup_subsys_state *blkiocg_create(struct cgroup_subsys *,
32                          struct cgroup *);
33static int blkiocg_can_attach(struct cgroup_subsys *, struct cgroup *,
34                  struct task_struct *, bool);
35static void blkiocg_attach(struct cgroup_subsys *, struct cgroup *,
36               struct cgroup *, struct task_struct *, bool);
37static void blkiocg_destroy(struct cgroup_subsys *, struct cgroup *);
38static 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
46struct 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};
60EXPORT_SYMBOL_GPL(blkio_subsys);
61
62static 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
68static 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 */
80static 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 */
90static 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 */
96static struct blkio_policy_node *
97blkio_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
110struct 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}
115EXPORT_SYMBOL_GPL(cgroup_to_blkio_cgroup);
116
117static inline void
118blkio_update_group_weight(struct blkio_group *blkg, unsigned int weight)
119{
120    struct blkio_policy_type *blkiop;
121
122    list_for_each_entry(blkiop, &blkio_list, list) {
123        /* If this policy does not own the blkg, do not send updates */
124        if (blkiop->plid != blkg->plid)
125            continue;
126        if (blkiop->ops.blkio_update_group_weight_fn)
127            blkiop->ops.blkio_update_group_weight_fn(blkg->key,
128                            blkg, weight);
129    }
130}
131
132static inline void blkio_update_group_bps(struct blkio_group *blkg, u64 bps,
133                int fileid)
134{
135    struct blkio_policy_type *blkiop;
136
137    list_for_each_entry(blkiop, &blkio_list, list) {
138
139        /* If this policy does not own the blkg, do not send updates */
140        if (blkiop->plid != blkg->plid)
141            continue;
142
143        if (fileid == BLKIO_THROTL_read_bps_device
144            && blkiop->ops.blkio_update_group_read_bps_fn)
145            blkiop->ops.blkio_update_group_read_bps_fn(blkg->key,
146                                blkg, bps);
147
148        if (fileid == BLKIO_THROTL_write_bps_device
149            && blkiop->ops.blkio_update_group_write_bps_fn)
150            blkiop->ops.blkio_update_group_write_bps_fn(blkg->key,
151                                blkg, bps);
152    }
153}
154
155static inline void blkio_update_group_iops(struct blkio_group *blkg,
156            unsigned int iops, int fileid)
157{
158    struct blkio_policy_type *blkiop;
159
160    list_for_each_entry(blkiop, &blkio_list, list) {
161
162        /* If this policy does not own the blkg, do not send updates */
163        if (blkiop->plid != blkg->plid)
164            continue;
165
166        if (fileid == BLKIO_THROTL_read_iops_device
167            && blkiop->ops.blkio_update_group_read_iops_fn)
168            blkiop->ops.blkio_update_group_read_iops_fn(blkg->key,
169                                blkg, iops);
170
171        if (fileid == BLKIO_THROTL_write_iops_device
172            && blkiop->ops.blkio_update_group_write_iops_fn)
173            blkiop->ops.blkio_update_group_write_iops_fn(blkg->key,
174                                blkg,iops);
175    }
176}
177
178/*
179 * Add to the appropriate stat variable depending on the request type.
180 * This should be called with the blkg->stats_lock held.
181 */
182static void blkio_add_stat(uint64_t *stat, uint64_t add, bool direction,
183                bool sync)
184{
185    if (direction)
186        stat[BLKIO_STAT_WRITE] += add;
187    else
188        stat[BLKIO_STAT_READ] += add;
189    if (sync)
190        stat[BLKIO_STAT_SYNC] += add;
191    else
192        stat[BLKIO_STAT_ASYNC] += add;
193}
194
195/*
196 * Decrements the appropriate stat variable if non-zero depending on the
197 * request type. Panics on value being zero.
198 * This should be called with the blkg->stats_lock held.
199 */
200static void blkio_check_and_dec_stat(uint64_t *stat, bool direction, bool sync)
201{
202    if (direction) {
203        BUG_ON(stat[BLKIO_STAT_WRITE] == 0);
204        stat[BLKIO_STAT_WRITE]--;
205    } else {
206        BUG_ON(stat[BLKIO_STAT_READ] == 0);
207        stat[BLKIO_STAT_READ]--;
208    }
209    if (sync) {
210        BUG_ON(stat[BLKIO_STAT_SYNC] == 0);
211        stat[BLKIO_STAT_SYNC]--;
212    } else {
213        BUG_ON(stat[BLKIO_STAT_ASYNC] == 0);
214        stat[BLKIO_STAT_ASYNC]--;
215    }
216}
217
218#ifdef CONFIG_DEBUG_BLK_CGROUP
219/* This should be called with the blkg->stats_lock held. */
220static void blkio_set_start_group_wait_time(struct blkio_group *blkg,
221                        struct blkio_group *curr_blkg)
222{
223    if (blkio_blkg_waiting(&blkg->stats))
224        return;
225    if (blkg == curr_blkg)
226        return;
227    blkg->stats.start_group_wait_time = sched_clock();
228    blkio_mark_blkg_waiting(&blkg->stats);
229}
230
231/* This should be called with the blkg->stats_lock held. */
232static void blkio_update_group_wait_time(struct blkio_group_stats *stats)
233{
234    unsigned long long now;
235
236    if (!blkio_blkg_waiting(stats))
237        return;
238
239    now = sched_clock();
240    if (time_after64(now, stats->start_group_wait_time))
241        stats->group_wait_time += now - stats->start_group_wait_time;
242    blkio_clear_blkg_waiting(stats);
243}
244
245/* This should be called with the blkg->stats_lock held. */
246static void blkio_end_empty_time(struct blkio_group_stats *stats)
247{
248    unsigned long long now;
249
250    if (!blkio_blkg_empty(stats))
251        return;
252
253    now = sched_clock();
254    if (time_after64(now, stats->start_empty_time))
255        stats->empty_time += now - stats->start_empty_time;
256    blkio_clear_blkg_empty(stats);
257}
258
259void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg)
260{
261    unsigned long flags;
262
263    spin_lock_irqsave(&blkg->stats_lock, flags);
264    BUG_ON(blkio_blkg_idling(&blkg->stats));
265    blkg->stats.start_idle_time = sched_clock();
266    blkio_mark_blkg_idling(&blkg->stats);
267    spin_unlock_irqrestore(&blkg->stats_lock, flags);
268}
269EXPORT_SYMBOL_GPL(blkiocg_update_set_idle_time_stats);
270
271void blkiocg_update_idle_time_stats(struct blkio_group *blkg)
272{
273    unsigned long flags;
274    unsigned long long now;
275    struct blkio_group_stats *stats;
276
277    spin_lock_irqsave(&blkg->stats_lock, flags);
278    stats = &blkg->stats;
279    if (blkio_blkg_idling(stats)) {
280        now = sched_clock();
281        if (time_after64(now, stats->start_idle_time))
282            stats->idle_time += now - stats->start_idle_time;
283        blkio_clear_blkg_idling(stats);
284    }
285    spin_unlock_irqrestore(&blkg->stats_lock, flags);
286}
287EXPORT_SYMBOL_GPL(blkiocg_update_idle_time_stats);
288
289void blkiocg_update_avg_queue_size_stats(struct blkio_group *blkg)
290{
291    unsigned long flags;
292    struct blkio_group_stats *stats;
293
294    spin_lock_irqsave(&blkg->stats_lock, flags);
295    stats = &blkg->stats;
296    stats->avg_queue_size_sum +=
297            stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] +
298            stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE];
299    stats->avg_queue_size_samples++;
300    blkio_update_group_wait_time(stats);
301    spin_unlock_irqrestore(&blkg->stats_lock, flags);
302}
303EXPORT_SYMBOL_GPL(blkiocg_update_avg_queue_size_stats);
304
305void blkiocg_set_start_empty_time(struct blkio_group *blkg)
306{
307    unsigned long flags;
308    struct blkio_group_stats *stats;
309
310    spin_lock_irqsave(&blkg->stats_lock, flags);
311    stats = &blkg->stats;
312
313    if (stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] ||
314            stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE]) {
315        spin_unlock_irqrestore(&blkg->stats_lock, flags);
316        return;
317    }
318
319    /*
320     * group is already marked empty. This can happen if cfqq got new
321     * request in parent group and moved to this group while being added
322     * to service tree. Just ignore the event and move on.
323     */
324    if(blkio_blkg_empty(stats)) {
325        spin_unlock_irqrestore(&blkg->stats_lock, flags);
326        return;
327    }
328
329    stats->start_empty_time = sched_clock();
330    blkio_mark_blkg_empty(stats);
331    spin_unlock_irqrestore(&blkg->stats_lock, flags);
332}
333EXPORT_SYMBOL_GPL(blkiocg_set_start_empty_time);
334
335void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
336            unsigned long dequeue)
337{
338    blkg->stats.dequeue += dequeue;
339}
340EXPORT_SYMBOL_GPL(blkiocg_update_dequeue_stats);
341#else
342static inline void blkio_set_start_group_wait_time(struct blkio_group *blkg,
343                    struct blkio_group *curr_blkg) {}
344static inline void blkio_end_empty_time(struct blkio_group_stats *stats) {}
345#endif
346
347void blkiocg_update_io_add_stats(struct blkio_group *blkg,
348            struct blkio_group *curr_blkg, bool direction,
349            bool sync)
350{
351    unsigned long flags;
352
353    spin_lock_irqsave(&blkg->stats_lock, flags);
354    blkio_add_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED], 1, direction,
355            sync);
356    blkio_end_empty_time(&blkg->stats);
357    blkio_set_start_group_wait_time(blkg, curr_blkg);
358    spin_unlock_irqrestore(&blkg->stats_lock, flags);
359}
360EXPORT_SYMBOL_GPL(blkiocg_update_io_add_stats);
361
362void blkiocg_update_io_remove_stats(struct blkio_group *blkg,
363                        bool direction, bool sync)
364{
365    unsigned long flags;
366
367    spin_lock_irqsave(&blkg->stats_lock, flags);
368    blkio_check_and_dec_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED],
369                    direction, sync);
370    spin_unlock_irqrestore(&blkg->stats_lock, flags);
371}
372EXPORT_SYMBOL_GPL(blkiocg_update_io_remove_stats);
373
374void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time)
375{
376    unsigned long flags;
377
378    spin_lock_irqsave(&blkg->stats_lock, flags);
379    blkg->stats.time += time;
380    spin_unlock_irqrestore(&blkg->stats_lock, flags);
381}
382EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);
383
384void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
385                uint64_t bytes, bool direction, bool sync)
386{
387    struct blkio_group_stats *stats;
388    unsigned long flags;
389
390    spin_lock_irqsave(&blkg->stats_lock, flags);
391    stats = &blkg->stats;
392    stats->sectors += bytes >> 9;
393    blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICED], 1, direction,
394            sync);
395    blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_BYTES], bytes,
396            direction, sync);
397    spin_unlock_irqrestore(&blkg->stats_lock, flags);
398}
399EXPORT_SYMBOL_GPL(blkiocg_update_dispatch_stats);
400
401void blkiocg_update_completion_stats(struct blkio_group *blkg,
402    uint64_t start_time, uint64_t io_start_time, bool direction, bool sync)
403{
404    struct blkio_group_stats *stats;
405    unsigned long flags;
406    unsigned long long now = sched_clock();
407
408    spin_lock_irqsave(&blkg->stats_lock, flags);
409    stats = &blkg->stats;
410    if (time_after64(now, io_start_time))
411        blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_TIME],
412                now - io_start_time, direction, sync);
413    if (time_after64(io_start_time, start_time))
414        blkio_add_stat(stats->stat_arr[BLKIO_STAT_WAIT_TIME],
415                io_start_time - start_time, direction, sync);
416    spin_unlock_irqrestore(&blkg->stats_lock, flags);
417}
418EXPORT_SYMBOL_GPL(blkiocg_update_completion_stats);
419
420void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction,
421                    bool sync)
422{
423    unsigned long flags;
424
425    spin_lock_irqsave(&blkg->stats_lock, flags);
426    blkio_add_stat(blkg->stats.stat_arr[BLKIO_STAT_MERGED], 1, direction,
427            sync);
428    spin_unlock_irqrestore(&blkg->stats_lock, flags);
429}
430EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats);
431
432void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
433        struct blkio_group *blkg, void *key, dev_t dev,
434        enum blkio_policy_id plid)
435{
436    unsigned long flags;
437
438    spin_lock_irqsave(&blkcg->lock, flags);
439    spin_lock_init(&blkg->stats_lock);
440    rcu_assign_pointer(blkg->key, key);
441    blkg->blkcg_id = css_id(&blkcg->css);
442    hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
443    blkg->plid = plid;
444    spin_unlock_irqrestore(&blkcg->lock, flags);
445    /* Need to take css reference ? */
446    cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
447    blkg->dev = dev;
448}
449EXPORT_SYMBOL_GPL(blkiocg_add_blkio_group);
450
451static void __blkiocg_del_blkio_group(struct blkio_group *blkg)
452{
453    hlist_del_init_rcu(&blkg->blkcg_node);
454    blkg->blkcg_id = 0;
455}
456
457/*
458 * returns 0 if blkio_group was still on cgroup list. Otherwise returns 1
459 * indicating that blk_group was unhashed by the time we got to it.
460 */
461int blkiocg_del_blkio_group(struct blkio_group *blkg)
462{
463    struct blkio_cgroup *blkcg;
464    unsigned long flags;
465    struct cgroup_subsys_state *css;
466    int ret = 1;
467
468    rcu_read_lock();
469    css = css_lookup(&blkio_subsys, blkg->blkcg_id);
470    if (css) {
471        blkcg = container_of(css, struct blkio_cgroup, css);
472        spin_lock_irqsave(&blkcg->lock, flags);
473        if (!hlist_unhashed(&blkg->blkcg_node)) {
474            __blkiocg_del_blkio_group(blkg);
475            ret = 0;
476        }
477        spin_unlock_irqrestore(&blkcg->lock, flags);
478    }
479
480    rcu_read_unlock();
481    return ret;
482}
483EXPORT_SYMBOL_GPL(blkiocg_del_blkio_group);
484
485/* called under rcu_read_lock(). */
486struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key)
487{
488    struct blkio_group *blkg;
489    struct hlist_node *n;
490    void *__key;
491
492    hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
493        __key = blkg->key;
494        if (__key == key)
495            return blkg;
496    }
497
498    return NULL;
499}
500EXPORT_SYMBOL_GPL(blkiocg_lookup_group);
501
502static int
503blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
504{
505    struct blkio_cgroup *blkcg;
506    struct blkio_group *blkg;
507    struct blkio_group_stats *stats;
508    struct hlist_node *n;
509    uint64_t queued[BLKIO_STAT_TOTAL];
510    int i;
511#ifdef CONFIG_DEBUG_BLK_CGROUP
512    bool idling, waiting, empty;
513    unsigned long long now = sched_clock();
514#endif
515
516    blkcg = cgroup_to_blkio_cgroup(cgroup);
517    spin_lock_irq(&blkcg->lock);
518    hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
519        spin_lock(&blkg->stats_lock);
520        stats = &blkg->stats;
521#ifdef CONFIG_DEBUG_BLK_CGROUP
522        idling = blkio_blkg_idling(stats);
523        waiting = blkio_blkg_waiting(stats);
524        empty = blkio_blkg_empty(stats);
525#endif
526        for (i = 0; i < BLKIO_STAT_TOTAL; i++)
527            queued[i] = stats->stat_arr[BLKIO_STAT_QUEUED][i];
528        memset(stats, 0, sizeof(struct blkio_group_stats));
529        for (i = 0; i < BLKIO_STAT_TOTAL; i++)
530            stats->stat_arr[BLKIO_STAT_QUEUED][i] = queued[i];
531#ifdef CONFIG_DEBUG_BLK_CGROUP
532        if (idling) {
533            blkio_mark_blkg_idling(stats);
534            stats->start_idle_time = now;
535        }
536        if (waiting) {
537            blkio_mark_blkg_waiting(stats);
538            stats->start_group_wait_time = now;
539        }
540        if (empty) {
541            blkio_mark_blkg_empty(stats);
542            stats->start_empty_time = now;
543        }
544#endif
545        spin_unlock(&blkg->stats_lock);
546    }
547    spin_unlock_irq(&blkcg->lock);
548    return 0;
549}
550
551static void blkio_get_key_name(enum stat_sub_type type, dev_t dev, char *str,
552                int chars_left, bool diskname_only)
553{
554    snprintf(str, chars_left, "%d:%d", MAJOR(dev), MINOR(dev));
555    chars_left -= strlen(str);
556    if (chars_left <= 0) {
557        printk(KERN_WARNING
558            "Possibly incorrect cgroup stat display format");
559        return;
560    }
561    if (diskname_only)
562        return;
563    switch (type) {
564    case BLKIO_STAT_READ:
565        strlcat(str, " Read", chars_left);
566        break;
567    case BLKIO_STAT_WRITE:
568        strlcat(str, " Write", chars_left);
569        break;
570    case BLKIO_STAT_SYNC:
571        strlcat(str, " Sync", chars_left);
572        break;
573    case BLKIO_STAT_ASYNC:
574        strlcat(str, " Async", chars_left);
575        break;
576    case BLKIO_STAT_TOTAL:
577        strlcat(str, " Total", chars_left);
578        break;
579    default:
580        strlcat(str, " Invalid", chars_left);
581    }
582}
583
584static uint64_t blkio_fill_stat(char *str, int chars_left, uint64_t val,
585                struct cgroup_map_cb *cb, dev_t dev)
586{
587    blkio_get_key_name(0, dev, str, chars_left, true);
588    cb->fill(cb, str, val);
589    return val;
590}
591
592/* This should be called with blkg->stats_lock held */
593static uint64_t blkio_get_stat(struct blkio_group *blkg,
594        struct cgroup_map_cb *cb, dev_t dev, enum stat_type type)
595{
596    uint64_t disk_total;
597    char key_str[MAX_KEY_LEN];
598    enum stat_sub_type sub_type;
599
600    if (type == BLKIO_STAT_TIME)
601        return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
602                    blkg->stats.time, cb, dev);
603    if (type == BLKIO_STAT_SECTORS)
604        return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
605                    blkg->stats.sectors, cb, dev);
606#ifdef CONFIG_DEBUG_BLK_CGROUP
607    if (type == BLKIO_STAT_AVG_QUEUE_SIZE) {
608        uint64_t sum = blkg->stats.avg_queue_size_sum;
609        uint64_t samples = blkg->stats.avg_queue_size_samples;
610        if (samples)
611            do_div(sum, samples);
612        else
613            sum = 0;
614        return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, sum, cb, dev);
615    }
616    if (type == BLKIO_STAT_GROUP_WAIT_TIME)
617        return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
618                    blkg->stats.group_wait_time, cb, dev);
619    if (type == BLKIO_STAT_IDLE_TIME)
620        return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
621                    blkg->stats.idle_time, cb, dev);
622    if (type == BLKIO_STAT_EMPTY_TIME)
623        return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
624                    blkg->stats.empty_time, cb, dev);
625    if (type == BLKIO_STAT_DEQUEUE)
626        return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
627                    blkg->stats.dequeue, cb, dev);
628#endif
629
630    for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL;
631            sub_type++) {
632        blkio_get_key_name(sub_type, dev, key_str, MAX_KEY_LEN, false);
633        cb->fill(cb, key_str, blkg->stats.stat_arr[type][sub_type]);
634    }
635    disk_total = blkg->stats.stat_arr[type][BLKIO_STAT_READ] +
636            blkg->stats.stat_arr[type][BLKIO_STAT_WRITE];
637    blkio_get_key_name(BLKIO_STAT_TOTAL, dev, key_str, MAX_KEY_LEN, false);
638    cb->fill(cb, key_str, disk_total);
639    return disk_total;
640}
641
642static 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
654static int blkio_policy_parse_and_set(char *buf,
655    struct blkio_policy_node *newpn, enum blkio_policy_id plid, int fileid)
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    u64 bps, iops;
663
664    memset(s, 0, sizeof(s));
665
666    while ((p = strsep(&buf, " ")) != NULL) {
667        if (!*p)
668            continue;
669
670        s[i++] = p;
671
672        /* Prevent from inputing too many things */
673        if (i == 3)
674            break;
675    }
676
677    if (i != 2)
678        return -EINVAL;
679
680    p = strsep(&s[0], ":");
681    if (p != NULL)
682        major_s = p;
683    else
684        return -EINVAL;
685
686    minor_s = s[0];
687    if (!minor_s)
688        return -EINVAL;
689
690    ret = strict_strtoul(major_s, 10, &major);
691    if (ret)
692        return -EINVAL;
693
694    ret = strict_strtoul(minor_s, 10, &minor);
695    if (ret)
696        return -EINVAL;
697
698    dev = MKDEV(major, minor);
699
700    ret = blkio_check_dev_num(dev);
701    if (ret)
702        return ret;
703
704    newpn->dev = dev;
705
706    if (s[1] == NULL)
707        return -EINVAL;
708
709    switch (plid) {
710    case BLKIO_POLICY_PROP:
711        ret = strict_strtoul(s[1], 10, &temp);
712        if (ret || (temp < BLKIO_WEIGHT_MIN && temp > 0) ||
713            temp > BLKIO_WEIGHT_MAX)
714            return -EINVAL;
715
716        newpn->plid = plid;
717        newpn->fileid = fileid;
718        newpn->val.weight = temp;
719        break;
720    case BLKIO_POLICY_THROTL:
721        switch(fileid) {
722        case BLKIO_THROTL_read_bps_device:
723        case BLKIO_THROTL_write_bps_device:
724            ret = strict_strtoull(s[1], 10, &bps);
725            if (ret)
726                return -EINVAL;
727
728            newpn->plid = plid;
729            newpn->fileid = fileid;
730            newpn->val.bps = bps;
731            break;
732        case BLKIO_THROTL_read_iops_device:
733        case BLKIO_THROTL_write_iops_device:
734            ret = strict_strtoull(s[1], 10, &iops);
735            if (ret)
736                return -EINVAL;
737
738            if (iops > THROTL_IOPS_MAX)
739                return -EINVAL;
740
741            newpn->plid = plid;
742            newpn->fileid = fileid;
743            newpn->val.iops = (unsigned int)iops;
744            break;
745        }
746        break;
747    default:
748        BUG();
749    }
750
751    return 0;
752}
753
754unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
755                  dev_t dev)
756{
757    struct blkio_policy_node *pn;
758
759    pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_PROP,
760                BLKIO_PROP_weight_device);
761    if (pn)
762        return pn->val.weight;
763    else
764        return blkcg->weight;
765}
766EXPORT_SYMBOL_GPL(blkcg_get_weight);
767
768uint64_t blkcg_get_read_bps(struct blkio_cgroup *blkcg, dev_t dev)
769{
770    struct blkio_policy_node *pn;
771
772    pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
773                BLKIO_THROTL_read_bps_device);
774    if (pn)
775        return pn->val.bps;
776    else
777        return -1;
778}
779
780uint64_t blkcg_get_write_bps(struct blkio_cgroup *blkcg, dev_t dev)
781{
782    struct blkio_policy_node *pn;
783    pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
784                BLKIO_THROTL_write_bps_device);
785    if (pn)
786        return pn->val.bps;
787    else
788        return -1;
789}
790
791unsigned int blkcg_get_read_iops(struct blkio_cgroup *blkcg, dev_t dev)
792{
793    struct blkio_policy_node *pn;
794
795    pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
796                BLKIO_THROTL_read_iops_device);
797    if (pn)
798        return pn->val.iops;
799    else
800        return -1;
801}
802
803unsigned int blkcg_get_write_iops(struct blkio_cgroup *blkcg, dev_t dev)
804{
805    struct blkio_policy_node *pn;
806    pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
807                BLKIO_THROTL_write_iops_device);
808    if (pn)
809        return pn->val.iops;
810    else
811        return -1;
812}
813
814/* Checks whether user asked for deleting a policy rule */
815static bool blkio_delete_rule_command(struct blkio_policy_node *pn)
816{
817    switch(pn->plid) {
818    case BLKIO_POLICY_PROP:
819        if (pn->val.weight == 0)
820            return 1;
821        break;
822    case BLKIO_POLICY_THROTL:
823        switch(pn->fileid) {
824        case BLKIO_THROTL_read_bps_device:
825        case BLKIO_THROTL_write_bps_device:
826            if (pn->val.bps == 0)
827                return 1;
828            break;
829        case BLKIO_THROTL_read_iops_device:
830        case BLKIO_THROTL_write_iops_device:
831            if (pn->val.iops == 0)
832                return 1;
833        }
834        break;
835    default:
836        BUG();
837    }
838
839    return 0;
840}
841
842static void blkio_update_policy_rule(struct blkio_policy_node *oldpn,
843                    struct blkio_policy_node *newpn)
844{
845    switch(oldpn->plid) {
846    case BLKIO_POLICY_PROP:
847        oldpn->val.weight = newpn->val.weight;
848        break;
849    case BLKIO_POLICY_THROTL:
850        switch(newpn->fileid) {
851        case BLKIO_THROTL_read_bps_device:
852        case BLKIO_THROTL_write_bps_device:
853            oldpn->val.bps = newpn->val.bps;
854            break;
855        case BLKIO_THROTL_read_iops_device:
856        case BLKIO_THROTL_write_iops_device:
857            oldpn->val.iops = newpn->val.iops;
858        }
859        break;
860    default:
861        BUG();
862    }
863}
864
865/*
866 * Some rules/values in blkg have changed. Propogate those to respective
867 * policies.
868 */
869static void blkio_update_blkg_policy(struct blkio_cgroup *blkcg,
870        struct blkio_group *blkg, struct blkio_policy_node *pn)
871{
872    unsigned int weight, iops;
873    u64 bps;
874
875    switch(pn->plid) {
876    case BLKIO_POLICY_PROP:
877        weight = pn->val.weight ? pn->val.weight :
878                blkcg->weight;
879        blkio_update_group_weight(blkg, weight);
880        break;
881    case BLKIO_POLICY_THROTL:
882        switch(pn->fileid) {
883        case BLKIO_THROTL_read_bps_device:
884        case BLKIO_THROTL_write_bps_device:
885            bps = pn->val.bps ? pn->val.bps : (-1);
886            blkio_update_group_bps(blkg, bps, pn->fileid);
887            break;
888        case BLKIO_THROTL_read_iops_device:
889        case BLKIO_THROTL_write_iops_device:
890            iops = pn->val.iops ? pn->val.iops : (-1);
891            blkio_update_group_iops(blkg, iops, pn->fileid);
892            break;
893        }
894        break;
895    default:
896        BUG();
897    }
898}
899
900/*
901 * A policy node rule has been updated. Propogate this update to all the
902 * block groups which might be affected by this update.
903 */
904static void blkio_update_policy_node_blkg(struct blkio_cgroup *blkcg,
905                struct blkio_policy_node *pn)
906{
907    struct blkio_group *blkg;
908    struct hlist_node *n;
909
910    spin_lock(&blkio_list_lock);
911    spin_lock_irq(&blkcg->lock);
912
913    hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
914        if (pn->dev != blkg->dev || pn->plid != blkg->plid)
915            continue;
916        blkio_update_blkg_policy(blkcg, blkg, pn);
917    }
918
919    spin_unlock_irq(&blkcg->lock);
920    spin_unlock(&blkio_list_lock);
921}
922
923static int blkiocg_file_write(struct cgroup *cgrp, struct cftype *cft,
924                        const char *buffer)
925{
926    int ret = 0;
927    char *buf;
928    struct blkio_policy_node *newpn, *pn;
929    struct blkio_cgroup *blkcg;
930    int keep_newpn = 0;
931    enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
932    int fileid = BLKIOFILE_ATTR(cft->private);
933
934    buf = kstrdup(buffer, GFP_KERNEL);
935    if (!buf)
936        return -ENOMEM;
937
938    newpn = kzalloc(sizeof(*newpn), GFP_KERNEL);
939    if (!newpn) {
940        ret = -ENOMEM;
941        goto free_buf;
942    }
943
944    ret = blkio_policy_parse_and_set(buf, newpn, plid, fileid);
945    if (ret)
946        goto free_newpn;
947
948    blkcg = cgroup_to_blkio_cgroup(cgrp);
949
950    spin_lock_irq(&blkcg->lock);
951
952    pn = blkio_policy_search_node(blkcg, newpn->dev, plid, fileid);
953    if (!pn) {
954        if (!blkio_delete_rule_command(newpn)) {
955            blkio_policy_insert_node(blkcg, newpn);
956            keep_newpn = 1;
957        }
958        spin_unlock_irq(&blkcg->lock);
959        goto update_io_group;
960    }
961
962    if (blkio_delete_rule_command(newpn)) {
963        blkio_policy_delete_node(pn);
964        spin_unlock_irq(&blkcg->lock);
965        goto update_io_group;
966    }
967    spin_unlock_irq(&blkcg->lock);
968
969    blkio_update_policy_rule(pn, newpn);
970
971update_io_group:
972    blkio_update_policy_node_blkg(blkcg, newpn);
973
974free_newpn:
975    if (!keep_newpn)
976        kfree(newpn);
977free_buf:
978    kfree(buf);
979    return ret;
980}
981
982static void
983blkio_print_policy_node(struct seq_file *m, struct blkio_policy_node *pn)
984{
985    switch(pn->plid) {
986        case BLKIO_POLICY_PROP:
987            if (pn->fileid == BLKIO_PROP_weight_device)
988                seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
989                    MINOR(pn->dev), pn->val.weight);
990            break;
991        case BLKIO_POLICY_THROTL:
992            switch(pn->fileid) {
993            case BLKIO_THROTL_read_bps_device:
994            case BLKIO_THROTL_write_bps_device:
995                seq_printf(m, "%u:%u\t%llu\n", MAJOR(pn->dev),
996                    MINOR(pn->dev), pn->val.bps);
997                break;
998            case BLKIO_THROTL_read_iops_device:
999            case BLKIO_THROTL_write_iops_device:
1000                seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
1001                    MINOR(pn->dev), pn->val.iops);
1002                break;
1003            }
1004            break;
1005        default:
1006            BUG();
1007    }
1008}
1009
1010/* cgroup files which read their data from policy nodes end up here */
1011static void blkio_read_policy_node_files(struct cftype *cft,
1012            struct blkio_cgroup *blkcg, struct seq_file *m)
1013{
1014    struct blkio_policy_node *pn;
1015
1016    if (!list_empty(&blkcg->policy_list)) {
1017        spin_lock_irq(&blkcg->lock);
1018        list_for_each_entry(pn, &blkcg->policy_list, node) {
1019            if (!pn_matches_cftype(cft, pn))
1020                continue;
1021            blkio_print_policy_node(m, pn);
1022        }
1023        spin_unlock_irq(&blkcg->lock);
1024    }
1025}
1026
1027static int blkiocg_file_read(struct cgroup *cgrp, struct cftype *cft,
1028                struct seq_file *m)
1029{
1030    struct blkio_cgroup *blkcg;
1031    enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1032    int name = BLKIOFILE_ATTR(cft->private);
1033
1034    blkcg = cgroup_to_blkio_cgroup(cgrp);
1035
1036    switch(plid) {
1037    case BLKIO_POLICY_PROP:
1038        switch(name) {
1039        case BLKIO_PROP_weight_device:
1040            blkio_read_policy_node_files(cft, blkcg, m);
1041            return 0;
1042        default:
1043            BUG();
1044        }
1045        break;
1046    case BLKIO_POLICY_THROTL:
1047        switch(name){
1048        case BLKIO_THROTL_read_bps_device:
1049        case BLKIO_THROTL_write_bps_device:
1050        case BLKIO_THROTL_read_iops_device:
1051        case BLKIO_THROTL_write_iops_device:
1052            blkio_read_policy_node_files(cft, blkcg, m);
1053            return 0;
1054        default:
1055            BUG();
1056        }
1057        break;
1058    default:
1059        BUG();
1060    }
1061
1062    return 0;
1063}
1064
1065static int blkio_read_blkg_stats(struct blkio_cgroup *blkcg,
1066        struct cftype *cft, struct cgroup_map_cb *cb, enum stat_type type,
1067        bool show_total)
1068{
1069    struct blkio_group *blkg;
1070    struct hlist_node *n;
1071    uint64_t cgroup_total = 0;
1072
1073    rcu_read_lock();
1074    hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
1075        if (blkg->dev) {
1076            if (!cftype_blkg_same_policy(cft, blkg))
1077                continue;
1078            spin_lock_irq(&blkg->stats_lock);
1079            cgroup_total += blkio_get_stat(blkg, cb, blkg->dev,
1080                        type);
1081            spin_unlock_irq(&blkg->stats_lock);
1082        }
1083    }
1084    if (show_total)
1085        cb->fill(cb, "Total", cgroup_total);
1086    rcu_read_unlock();
1087    return 0;
1088}
1089
1090/* All map kind of cgroup file get serviced by this function */
1091static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft,
1092                struct cgroup_map_cb *cb)
1093{
1094    struct blkio_cgroup *blkcg;
1095    enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1096    int name = BLKIOFILE_ATTR(cft->private);
1097
1098    blkcg = cgroup_to_blkio_cgroup(cgrp);
1099
1100    switch(plid) {
1101    case BLKIO_POLICY_PROP:
1102        switch(name) {
1103        case BLKIO_PROP_time:
1104            return blkio_read_blkg_stats(blkcg, cft, cb,
1105                        BLKIO_STAT_TIME, 0);
1106        case BLKIO_PROP_sectors:
1107            return blkio_read_blkg_stats(blkcg, cft, cb,
1108                        BLKIO_STAT_SECTORS, 0);
1109        case BLKIO_PROP_io_service_bytes:
1110            return blkio_read_blkg_stats(blkcg, cft, cb,
1111                        BLKIO_STAT_SERVICE_BYTES, 1);
1112        case BLKIO_PROP_io_serviced:
1113            return blkio_read_blkg_stats(blkcg, cft, cb,
1114                        BLKIO_STAT_SERVICED, 1);
1115        case BLKIO_PROP_io_service_time:
1116            return blkio_read_blkg_stats(blkcg, cft, cb,
1117                        BLKIO_STAT_SERVICE_TIME, 1);
1118        case BLKIO_PROP_io_wait_time:
1119            return blkio_read_blkg_stats(blkcg, cft, cb,
1120                        BLKIO_STAT_WAIT_TIME, 1);
1121        case BLKIO_PROP_io_merged:
1122            return blkio_read_blkg_stats(blkcg, cft, cb,
1123                        BLKIO_STAT_MERGED, 1);
1124        case BLKIO_PROP_io_queued:
1125            return blkio_read_blkg_stats(blkcg, cft, cb,
1126                        BLKIO_STAT_QUEUED, 1);
1127#ifdef CONFIG_DEBUG_BLK_CGROUP
1128        case BLKIO_PROP_dequeue:
1129            return blkio_read_blkg_stats(blkcg, cft, cb,
1130                        BLKIO_STAT_DEQUEUE, 0);
1131        case BLKIO_PROP_avg_queue_size:
1132            return blkio_read_blkg_stats(blkcg, cft, cb,
1133                        BLKIO_STAT_AVG_QUEUE_SIZE, 0);
1134        case BLKIO_PROP_group_wait_time:
1135            return blkio_read_blkg_stats(blkcg, cft, cb,
1136                        BLKIO_STAT_GROUP_WAIT_TIME, 0);
1137        case BLKIO_PROP_idle_time:
1138            return blkio_read_blkg_stats(blkcg, cft, cb,
1139                        BLKIO_STAT_IDLE_TIME, 0);
1140        case BLKIO_PROP_empty_time:
1141            return blkio_read_blkg_stats(blkcg, cft, cb,
1142                        BLKIO_STAT_EMPTY_TIME, 0);
1143#endif
1144        default:
1145            BUG();
1146        }
1147        break;
1148    case BLKIO_POLICY_THROTL:
1149        switch(name){
1150        case BLKIO_THROTL_io_service_bytes:
1151            return blkio_read_blkg_stats(blkcg, cft, cb,
1152                        BLKIO_STAT_SERVICE_BYTES, 1);
1153        case BLKIO_THROTL_io_serviced:
1154            return blkio_read_blkg_stats(blkcg, cft, cb,
1155                        BLKIO_STAT_SERVICED, 1);
1156        default:
1157            BUG();
1158        }
1159        break;
1160    default:
1161        BUG();
1162    }
1163
1164    return 0;
1165}
1166
1167static int blkio_weight_write(struct blkio_cgroup *blkcg, u64 val)
1168{
1169    struct blkio_group *blkg;
1170    struct hlist_node *n;
1171    struct blkio_policy_node *pn;
1172
1173    if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
1174        return -EINVAL;
1175
1176    spin_lock(&blkio_list_lock);
1177    spin_lock_irq(&blkcg->lock);
1178    blkcg->weight = (unsigned int)val;
1179
1180    hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
1181        pn = blkio_policy_search_node(blkcg, blkg->dev,
1182                BLKIO_POLICY_PROP, BLKIO_PROP_weight_device);
1183        if (pn)
1184            continue;
1185
1186        blkio_update_group_weight(blkg, blkcg->weight);
1187    }
1188    spin_unlock_irq(&blkcg->lock);
1189    spin_unlock(&blkio_list_lock);
1190    return 0;
1191}
1192
1193static u64 blkiocg_file_read_u64 (struct cgroup *cgrp, struct cftype *cft) {
1194    struct blkio_cgroup *blkcg;
1195    enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1196    int name = BLKIOFILE_ATTR(cft->private);
1197
1198    blkcg = cgroup_to_blkio_cgroup(cgrp);
1199
1200    switch(plid) {
1201    case BLKIO_POLICY_PROP:
1202        switch(name) {
1203        case BLKIO_PROP_weight:
1204            return (u64)blkcg->weight;
1205        }
1206        break;
1207    default:
1208        BUG();
1209    }
1210    return 0;
1211}
1212
1213static int
1214blkiocg_file_write_u64(struct cgroup *cgrp, struct cftype *cft, u64 val)
1215{
1216    struct blkio_cgroup *blkcg;
1217    enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1218    int name = BLKIOFILE_ATTR(cft->private);
1219
1220    blkcg = cgroup_to_blkio_cgroup(cgrp);
1221
1222    switch(plid) {
1223    case BLKIO_POLICY_PROP:
1224        switch(name) {
1225        case BLKIO_PROP_weight:
1226            return blkio_weight_write(blkcg, val);
1227        }
1228        break;
1229    default:
1230        BUG();
1231    }
1232
1233    return 0;
1234}
1235
1236struct cftype blkio_files[] = {
1237    {
1238        .name = "weight_device",
1239        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1240                BLKIO_PROP_weight_device),
1241        .read_seq_string = blkiocg_file_read,
1242        .write_string = blkiocg_file_write,
1243        .max_write_len = 256,
1244    },
1245    {
1246        .name = "weight",
1247        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1248                BLKIO_PROP_weight),
1249        .read_u64 = blkiocg_file_read_u64,
1250        .write_u64 = blkiocg_file_write_u64,
1251    },
1252    {
1253        .name = "time",
1254        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1255                BLKIO_PROP_time),
1256        .read_map = blkiocg_file_read_map,
1257    },
1258    {
1259        .name = "sectors",
1260        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1261                BLKIO_PROP_sectors),
1262        .read_map = blkiocg_file_read_map,
1263    },
1264    {
1265        .name = "io_service_bytes",
1266        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1267                BLKIO_PROP_io_service_bytes),
1268        .read_map = blkiocg_file_read_map,
1269    },
1270    {
1271        .name = "io_serviced",
1272        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1273                BLKIO_PROP_io_serviced),
1274        .read_map = blkiocg_file_read_map,
1275    },
1276    {
1277        .name = "io_service_time",
1278        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1279                BLKIO_PROP_io_service_time),
1280        .read_map = blkiocg_file_read_map,
1281    },
1282    {
1283        .name = "io_wait_time",
1284        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1285                BLKIO_PROP_io_wait_time),
1286        .read_map = blkiocg_file_read_map,
1287    },
1288    {
1289        .name = "io_merged",
1290        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1291                BLKIO_PROP_io_merged),
1292        .read_map = blkiocg_file_read_map,
1293    },
1294    {
1295        .name = "io_queued",
1296        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1297                BLKIO_PROP_io_queued),
1298        .read_map = blkiocg_file_read_map,
1299    },
1300    {
1301        .name = "reset_stats",
1302        .write_u64 = blkiocg_reset_stats,
1303    },
1304#ifdef CONFIG_BLK_DEV_THROTTLING
1305    {
1306        .name = "throttle.read_bps_device",
1307        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1308                BLKIO_THROTL_read_bps_device),
1309        .read_seq_string = blkiocg_file_read,
1310        .write_string = blkiocg_file_write,
1311        .max_write_len = 256,
1312    },
1313
1314    {
1315        .name = "throttle.write_bps_device",
1316        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1317                BLKIO_THROTL_write_bps_device),
1318        .read_seq_string = blkiocg_file_read,
1319        .write_string = blkiocg_file_write,
1320        .max_write_len = 256,
1321    },
1322
1323    {
1324        .name = "throttle.read_iops_device",
1325        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1326                BLKIO_THROTL_read_iops_device),
1327        .read_seq_string = blkiocg_file_read,
1328        .write_string = blkiocg_file_write,
1329        .max_write_len = 256,
1330    },
1331
1332    {
1333        .name = "throttle.write_iops_device",
1334        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1335                BLKIO_THROTL_write_iops_device),
1336        .read_seq_string = blkiocg_file_read,
1337        .write_string = blkiocg_file_write,
1338        .max_write_len = 256,
1339    },
1340    {
1341        .name = "throttle.io_service_bytes",
1342        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1343                BLKIO_THROTL_io_service_bytes),
1344        .read_map = blkiocg_file_read_map,
1345    },
1346    {
1347        .name = "throttle.io_serviced",
1348        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1349                BLKIO_THROTL_io_serviced),
1350        .read_map = blkiocg_file_read_map,
1351    },
1352#endif /* CONFIG_BLK_DEV_THROTTLING */
1353
1354#ifdef CONFIG_DEBUG_BLK_CGROUP
1355    {
1356        .name = "avg_queue_size",
1357        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1358                BLKIO_PROP_avg_queue_size),
1359        .read_map = blkiocg_file_read_map,
1360    },
1361    {
1362        .name = "group_wait_time",
1363        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1364                BLKIO_PROP_group_wait_time),
1365        .read_map = blkiocg_file_read_map,
1366    },
1367    {
1368        .name = "idle_time",
1369        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1370                BLKIO_PROP_idle_time),
1371        .read_map = blkiocg_file_read_map,
1372    },
1373    {
1374        .name = "empty_time",
1375        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1376                BLKIO_PROP_empty_time),
1377        .read_map = blkiocg_file_read_map,
1378    },
1379    {
1380        .name = "dequeue",
1381        .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1382                BLKIO_PROP_dequeue),
1383        .read_map = blkiocg_file_read_map,
1384    },
1385#endif
1386};
1387
1388static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1389{
1390    return cgroup_add_files(cgroup, subsys, blkio_files,
1391                ARRAY_SIZE(blkio_files));
1392}
1393
1394static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1395{
1396    struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
1397    unsigned long flags;
1398    struct blkio_group *blkg;
1399    void *key;
1400    struct blkio_policy_type *blkiop;
1401    struct blkio_policy_node *pn, *pntmp;
1402
1403    rcu_read_lock();
1404    do {
1405        spin_lock_irqsave(&blkcg->lock, flags);
1406
1407        if (hlist_empty(&blkcg->blkg_list)) {
1408            spin_unlock_irqrestore(&blkcg->lock, flags);
1409            break;
1410        }
1411
1412        blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group,
1413                    blkcg_node);
1414        key = rcu_dereference(blkg->key);
1415        __blkiocg_del_blkio_group(blkg);
1416
1417        spin_unlock_irqrestore(&blkcg->lock, flags);
1418
1419        /*
1420         * This blkio_group is being unlinked as associated cgroup is
1421         * going away. Let all the IO controlling policies know about
1422         * this event.
1423         */
1424        spin_lock(&blkio_list_lock);
1425        list_for_each_entry(blkiop, &blkio_list, list) {
1426            if (blkiop->plid != blkg->plid)
1427                continue;
1428            blkiop->ops.blkio_unlink_group_fn(key, blkg);
1429        }
1430        spin_unlock(&blkio_list_lock);
1431    } while (1);
1432
1433    list_for_each_entry_safe(pn, pntmp, &blkcg->policy_list, node) {
1434        blkio_policy_delete_node(pn);
1435        kfree(pn);
1436    }
1437
1438    free_css_id(&blkio_subsys, &blkcg->css);
1439    rcu_read_unlock();
1440    if (blkcg != &blkio_root_cgroup)
1441        kfree(blkcg);
1442}
1443
1444static struct cgroup_subsys_state *
1445blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1446{
1447    struct blkio_cgroup *blkcg;
1448    struct cgroup *parent = cgroup->parent;
1449
1450    if (!parent) {
1451        blkcg = &blkio_root_cgroup;
1452        goto done;
1453    }
1454
1455    /* Currently we do not support hierarchy deeper than two level (0,1) */
1456    if (parent != cgroup->top_cgroup)
1457        return ERR_PTR(-EPERM);
1458
1459    blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
1460    if (!blkcg)
1461        return ERR_PTR(-ENOMEM);
1462
1463    blkcg->weight = BLKIO_WEIGHT_DEFAULT;
1464done:
1465    spin_lock_init(&blkcg->lock);
1466    INIT_HLIST_HEAD(&blkcg->blkg_list);
1467
1468    INIT_LIST_HEAD(&blkcg->policy_list);
1469    return &blkcg->css;
1470}
1471
1472/*
1473 * We cannot support shared io contexts, as we have no mean to support
1474 * two tasks with the same ioc in two different groups without major rework
1475 * of the main cic data structures. For now we allow a task to change
1476 * its cgroup only if it's the only owner of its ioc.
1477 */
1478static int blkiocg_can_attach(struct cgroup_subsys *subsys,
1479                struct cgroup *cgroup, struct task_struct *tsk,
1480                bool threadgroup)
1481{
1482    struct io_context *ioc;
1483    int ret = 0;
1484
1485    /* task_lock() is needed to avoid races with exit_io_context() */
1486    task_lock(tsk);
1487    ioc = tsk->io_context;
1488    if (ioc && atomic_read(&ioc->nr_tasks) > 1)
1489        ret = -EINVAL;
1490    task_unlock(tsk);
1491
1492    return ret;
1493}
1494
1495static void blkiocg_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup,
1496                struct cgroup *prev, struct task_struct *tsk,
1497                bool threadgroup)
1498{
1499    struct io_context *ioc;
1500
1501    task_lock(tsk);
1502    ioc = tsk->io_context;
1503    if (ioc)
1504        ioc->cgroup_changed = 1;
1505    task_unlock(tsk);
1506}
1507
1508void blkio_policy_register(struct blkio_policy_type *blkiop)
1509{
1510    spin_lock(&blkio_list_lock);
1511    list_add_tail(&blkiop->list, &blkio_list);
1512    spin_unlock(&blkio_list_lock);
1513}
1514EXPORT_SYMBOL_GPL(blkio_policy_register);
1515
1516void blkio_policy_unregister(struct blkio_policy_type *blkiop)
1517{
1518    spin_lock(&blkio_list_lock);
1519    list_del_init(&blkiop->list);
1520    spin_unlock(&blkio_list_lock);
1521}
1522EXPORT_SYMBOL_GPL(blkio_policy_unregister);
1523
1524static int __init init_cgroup_blkio(void)
1525{
1526    return cgroup_load_subsys(&blkio_subsys);
1527}
1528
1529static void __exit exit_cgroup_blkio(void)
1530{
1531    cgroup_unload_subsys(&blkio_subsys);
1532}
1533
1534module_init(init_cgroup_blkio);
1535module_exit(exit_cgroup_blkio);
1536MODULE_LICENSE("GPL");
1537

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