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[karo-tx-linux.git] / drivers / md / dm-stats.c
1 #include <linux/errno.h>
2 #include <linux/numa.h>
3 #include <linux/slab.h>
4 #include <linux/rculist.h>
5 #include <linux/threads.h>
6 #include <linux/preempt.h>
7 #include <linux/irqflags.h>
8 #include <linux/vmalloc.h>
9 #include <linux/mm.h>
10 #include <linux/module.h>
11 #include <linux/device-mapper.h>
12
13 #include "dm.h"
14 #include "dm-stats.h"
15
16 #define DM_MSG_PREFIX "stats"
17
18 static int dm_stat_need_rcu_barrier;
19
20 /*
21  * Using 64-bit values to avoid overflow (which is a
22  * problem that block/genhd.c's IO accounting has).
23  */
24 struct dm_stat_percpu {
25         unsigned long long sectors[2];
26         unsigned long long ios[2];
27         unsigned long long merges[2];
28         unsigned long long ticks[2];
29         unsigned long long io_ticks[2];
30         unsigned long long io_ticks_total;
31         unsigned long long time_in_queue;
32 };
33
34 struct dm_stat_shared {
35         atomic_t in_flight[2];
36         unsigned long stamp;
37         struct dm_stat_percpu tmp;
38 };
39
40 struct dm_stat {
41         struct list_head list_entry;
42         int id;
43         size_t n_entries;
44         sector_t start;
45         sector_t end;
46         sector_t step;
47         const char *program_id;
48         const char *aux_data;
49         struct rcu_head rcu_head;
50         size_t shared_alloc_size;
51         size_t percpu_alloc_size;
52         struct dm_stat_percpu *stat_percpu[NR_CPUS];
53         struct dm_stat_shared stat_shared[0];
54 };
55
56 struct dm_stats_last_position {
57         sector_t last_sector;
58         unsigned last_rw;
59 };
60
61 /*
62  * A typo on the command line could possibly make the kernel run out of memory
63  * and crash. To prevent the crash we account all used memory. We fail if we
64  * exhaust 1/4 of all memory or 1/2 of vmalloc space.
65  */
66 #define DM_STATS_MEMORY_FACTOR          4
67 #define DM_STATS_VMALLOC_FACTOR         2
68
69 static DEFINE_SPINLOCK(shared_memory_lock);
70
71 static unsigned long shared_memory_amount;
72
73 static bool __check_shared_memory(size_t alloc_size)
74 {
75         size_t a;
76
77         a = shared_memory_amount + alloc_size;
78         if (a < shared_memory_amount)
79                 return false;
80         if (a >> PAGE_SHIFT > totalram_pages / DM_STATS_MEMORY_FACTOR)
81                 return false;
82 #ifdef CONFIG_MMU
83         if (a > (VMALLOC_END - VMALLOC_START) / DM_STATS_VMALLOC_FACTOR)
84                 return false;
85 #endif
86         return true;
87 }
88
89 static bool check_shared_memory(size_t alloc_size)
90 {
91         bool ret;
92
93         spin_lock_irq(&shared_memory_lock);
94
95         ret = __check_shared_memory(alloc_size);
96
97         spin_unlock_irq(&shared_memory_lock);
98
99         return ret;
100 }
101
102 static bool claim_shared_memory(size_t alloc_size)
103 {
104         spin_lock_irq(&shared_memory_lock);
105
106         if (!__check_shared_memory(alloc_size)) {
107                 spin_unlock_irq(&shared_memory_lock);
108                 return false;
109         }
110
111         shared_memory_amount += alloc_size;
112
113         spin_unlock_irq(&shared_memory_lock);
114
115         return true;
116 }
117
118 static void free_shared_memory(size_t alloc_size)
119 {
120         unsigned long flags;
121
122         spin_lock_irqsave(&shared_memory_lock, flags);
123
124         if (WARN_ON_ONCE(shared_memory_amount < alloc_size)) {
125                 spin_unlock_irqrestore(&shared_memory_lock, flags);
126                 DMCRIT("Memory usage accounting bug.");
127                 return;
128         }
129
130         shared_memory_amount -= alloc_size;
131
132         spin_unlock_irqrestore(&shared_memory_lock, flags);
133 }
134
135 static void *dm_kvzalloc(size_t alloc_size, int node)
136 {
137         void *p;
138
139         if (!claim_shared_memory(alloc_size))
140                 return NULL;
141
142         if (alloc_size <= KMALLOC_MAX_SIZE) {
143                 p = kzalloc_node(alloc_size, GFP_KERNEL | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN, node);
144                 if (p)
145                         return p;
146         }
147         p = vzalloc_node(alloc_size, node);
148         if (p)
149                 return p;
150
151         free_shared_memory(alloc_size);
152
153         return NULL;
154 }
155
156 static void dm_kvfree(void *ptr, size_t alloc_size)
157 {
158         if (!ptr)
159                 return;
160
161         free_shared_memory(alloc_size);
162
163         if (is_vmalloc_addr(ptr))
164                 vfree(ptr);
165         else
166                 kfree(ptr);
167 }
168
169 static void dm_stat_free(struct rcu_head *head)
170 {
171         int cpu;
172         struct dm_stat *s = container_of(head, struct dm_stat, rcu_head);
173
174         kfree(s->program_id);
175         kfree(s->aux_data);
176         for_each_possible_cpu(cpu)
177                 dm_kvfree(s->stat_percpu[cpu], s->percpu_alloc_size);
178         dm_kvfree(s, s->shared_alloc_size);
179 }
180
181 static int dm_stat_in_flight(struct dm_stat_shared *shared)
182 {
183         return atomic_read(&shared->in_flight[READ]) +
184                atomic_read(&shared->in_flight[WRITE]);
185 }
186
187 void dm_stats_init(struct dm_stats *stats)
188 {
189         int cpu;
190         struct dm_stats_last_position *last;
191
192         mutex_init(&stats->mutex);
193         INIT_LIST_HEAD(&stats->list);
194         stats->last = alloc_percpu(struct dm_stats_last_position);
195         for_each_possible_cpu(cpu) {
196                 last = per_cpu_ptr(stats->last, cpu);
197                 last->last_sector = (sector_t)ULLONG_MAX;
198                 last->last_rw = UINT_MAX;
199         }
200 }
201
202 void dm_stats_cleanup(struct dm_stats *stats)
203 {
204         size_t ni;
205         struct dm_stat *s;
206         struct dm_stat_shared *shared;
207
208         while (!list_empty(&stats->list)) {
209                 s = container_of(stats->list.next, struct dm_stat, list_entry);
210                 list_del(&s->list_entry);
211                 for (ni = 0; ni < s->n_entries; ni++) {
212                         shared = &s->stat_shared[ni];
213                         if (WARN_ON(dm_stat_in_flight(shared))) {
214                                 DMCRIT("leaked in-flight counter at index %lu "
215                                        "(start %llu, end %llu, step %llu): reads %d, writes %d",
216                                        (unsigned long)ni,
217                                        (unsigned long long)s->start,
218                                        (unsigned long long)s->end,
219                                        (unsigned long long)s->step,
220                                        atomic_read(&shared->in_flight[READ]),
221                                        atomic_read(&shared->in_flight[WRITE]));
222                         }
223                 }
224                 dm_stat_free(&s->rcu_head);
225         }
226         free_percpu(stats->last);
227 }
228
229 static int dm_stats_create(struct dm_stats *stats, sector_t start, sector_t end,
230                            sector_t step, const char *program_id, const char *aux_data,
231                            void (*suspend_callback)(struct mapped_device *),
232                            void (*resume_callback)(struct mapped_device *),
233                            struct mapped_device *md)
234 {
235         struct list_head *l;
236         struct dm_stat *s, *tmp_s;
237         sector_t n_entries;
238         size_t ni;
239         size_t shared_alloc_size;
240         size_t percpu_alloc_size;
241         struct dm_stat_percpu *p;
242         int cpu;
243         int ret_id;
244         int r;
245
246         if (end < start || !step)
247                 return -EINVAL;
248
249         n_entries = end - start;
250         if (dm_sector_div64(n_entries, step))
251                 n_entries++;
252
253         if (n_entries != (size_t)n_entries || !(size_t)(n_entries + 1))
254                 return -EOVERFLOW;
255
256         shared_alloc_size = sizeof(struct dm_stat) + (size_t)n_entries * sizeof(struct dm_stat_shared);
257         if ((shared_alloc_size - sizeof(struct dm_stat)) / sizeof(struct dm_stat_shared) != n_entries)
258                 return -EOVERFLOW;
259
260         percpu_alloc_size = (size_t)n_entries * sizeof(struct dm_stat_percpu);
261         if (percpu_alloc_size / sizeof(struct dm_stat_percpu) != n_entries)
262                 return -EOVERFLOW;
263
264         if (!check_shared_memory(shared_alloc_size + num_possible_cpus() * percpu_alloc_size))
265                 return -ENOMEM;
266
267         s = dm_kvzalloc(shared_alloc_size, NUMA_NO_NODE);
268         if (!s)
269                 return -ENOMEM;
270
271         s->n_entries = n_entries;
272         s->start = start;
273         s->end = end;
274         s->step = step;
275         s->shared_alloc_size = shared_alloc_size;
276         s->percpu_alloc_size = percpu_alloc_size;
277
278         s->program_id = kstrdup(program_id, GFP_KERNEL);
279         if (!s->program_id) {
280                 r = -ENOMEM;
281                 goto out;
282         }
283         s->aux_data = kstrdup(aux_data, GFP_KERNEL);
284         if (!s->aux_data) {
285                 r = -ENOMEM;
286                 goto out;
287         }
288
289         for (ni = 0; ni < n_entries; ni++) {
290                 atomic_set(&s->stat_shared[ni].in_flight[READ], 0);
291                 atomic_set(&s->stat_shared[ni].in_flight[WRITE], 0);
292         }
293
294         for_each_possible_cpu(cpu) {
295                 p = dm_kvzalloc(percpu_alloc_size, cpu_to_node(cpu));
296                 if (!p) {
297                         r = -ENOMEM;
298                         goto out;
299                 }
300                 s->stat_percpu[cpu] = p;
301         }
302
303         /*
304          * Suspend/resume to make sure there is no i/o in flight,
305          * so that newly created statistics will be exact.
306          *
307          * (note: we couldn't suspend earlier because we must not
308          * allocate memory while suspended)
309          */
310         suspend_callback(md);
311
312         mutex_lock(&stats->mutex);
313         s->id = 0;
314         list_for_each(l, &stats->list) {
315                 tmp_s = container_of(l, struct dm_stat, list_entry);
316                 if (WARN_ON(tmp_s->id < s->id)) {
317                         r = -EINVAL;
318                         goto out_unlock_resume;
319                 }
320                 if (tmp_s->id > s->id)
321                         break;
322                 if (unlikely(s->id == INT_MAX)) {
323                         r = -ENFILE;
324                         goto out_unlock_resume;
325                 }
326                 s->id++;
327         }
328         ret_id = s->id;
329         list_add_tail_rcu(&s->list_entry, l);
330         mutex_unlock(&stats->mutex);
331
332         resume_callback(md);
333
334         return ret_id;
335
336 out_unlock_resume:
337         mutex_unlock(&stats->mutex);
338         resume_callback(md);
339 out:
340         dm_stat_free(&s->rcu_head);
341         return r;
342 }
343
344 static struct dm_stat *__dm_stats_find(struct dm_stats *stats, int id)
345 {
346         struct dm_stat *s;
347
348         list_for_each_entry(s, &stats->list, list_entry) {
349                 if (s->id > id)
350                         break;
351                 if (s->id == id)
352                         return s;
353         }
354
355         return NULL;
356 }
357
358 static int dm_stats_delete(struct dm_stats *stats, int id)
359 {
360         struct dm_stat *s;
361         int cpu;
362
363         mutex_lock(&stats->mutex);
364
365         s = __dm_stats_find(stats, id);
366         if (!s) {
367                 mutex_unlock(&stats->mutex);
368                 return -ENOENT;
369         }
370
371         list_del_rcu(&s->list_entry);
372         mutex_unlock(&stats->mutex);
373
374         /*
375          * vfree can't be called from RCU callback
376          */
377         for_each_possible_cpu(cpu)
378                 if (is_vmalloc_addr(s->stat_percpu))
379                         goto do_sync_free;
380         if (is_vmalloc_addr(s)) {
381 do_sync_free:
382                 synchronize_rcu_expedited();
383                 dm_stat_free(&s->rcu_head);
384         } else {
385                 ACCESS_ONCE(dm_stat_need_rcu_barrier) = 1;
386                 call_rcu(&s->rcu_head, dm_stat_free);
387         }
388         return 0;
389 }
390
391 static int dm_stats_list(struct dm_stats *stats, const char *program,
392                          char *result, unsigned maxlen)
393 {
394         struct dm_stat *s;
395         sector_t len;
396         unsigned sz = 0;
397
398         /*
399          * Output format:
400          *   <region_id>: <start_sector>+<length> <step> <program_id> <aux_data>
401          */
402
403         mutex_lock(&stats->mutex);
404         list_for_each_entry(s, &stats->list, list_entry) {
405                 if (!program || !strcmp(program, s->program_id)) {
406                         len = s->end - s->start;
407                         DMEMIT("%d: %llu+%llu %llu %s %s\n", s->id,
408                                 (unsigned long long)s->start,
409                                 (unsigned long long)len,
410                                 (unsigned long long)s->step,
411                                 s->program_id,
412                                 s->aux_data);
413                 }
414         }
415         mutex_unlock(&stats->mutex);
416
417         return 1;
418 }
419
420 static void dm_stat_round(struct dm_stat_shared *shared, struct dm_stat_percpu *p)
421 {
422         /*
423          * This is racy, but so is part_round_stats_single.
424          */
425         unsigned long now = jiffies;
426         unsigned in_flight_read;
427         unsigned in_flight_write;
428         unsigned long difference = now - shared->stamp;
429
430         if (!difference)
431                 return;
432         in_flight_read = (unsigned)atomic_read(&shared->in_flight[READ]);
433         in_flight_write = (unsigned)atomic_read(&shared->in_flight[WRITE]);
434         if (in_flight_read)
435                 p->io_ticks[READ] += difference;
436         if (in_flight_write)
437                 p->io_ticks[WRITE] += difference;
438         if (in_flight_read + in_flight_write) {
439                 p->io_ticks_total += difference;
440                 p->time_in_queue += (in_flight_read + in_flight_write) * difference;
441         }
442         shared->stamp = now;
443 }
444
445 static void dm_stat_for_entry(struct dm_stat *s, size_t entry,
446                               unsigned long bi_rw, sector_t len, bool merged,
447                               bool end, unsigned long duration)
448 {
449         unsigned long idx = bi_rw & REQ_WRITE;
450         struct dm_stat_shared *shared = &s->stat_shared[entry];
451         struct dm_stat_percpu *p;
452
453         /*
454          * For strict correctness we should use local_irq_save/restore
455          * instead of preempt_disable/enable.
456          *
457          * preempt_disable/enable is racy if the driver finishes bios
458          * from non-interrupt context as well as from interrupt context
459          * or from more different interrupts.
460          *
461          * On 64-bit architectures the race only results in not counting some
462          * events, so it is acceptable.  On 32-bit architectures the race could
463          * cause the counter going off by 2^32, so we need to do proper locking
464          * there.
465          *
466          * part_stat_lock()/part_stat_unlock() have this race too.
467          */
468 #if BITS_PER_LONG == 32
469         unsigned long flags;
470         local_irq_save(flags);
471 #else
472         preempt_disable();
473 #endif
474         p = &s->stat_percpu[smp_processor_id()][entry];
475
476         if (!end) {
477                 dm_stat_round(shared, p);
478                 atomic_inc(&shared->in_flight[idx]);
479         } else {
480                 dm_stat_round(shared, p);
481                 atomic_dec(&shared->in_flight[idx]);
482                 p->sectors[idx] += len;
483                 p->ios[idx] += 1;
484                 p->merges[idx] += merged;
485                 p->ticks[idx] += duration;
486         }
487
488 #if BITS_PER_LONG == 32
489         local_irq_restore(flags);
490 #else
491         preempt_enable();
492 #endif
493 }
494
495 static void __dm_stat_bio(struct dm_stat *s, unsigned long bi_rw,
496                           sector_t bi_sector, sector_t end_sector,
497                           bool end, unsigned long duration,
498                           struct dm_stats_aux *stats_aux)
499 {
500         sector_t rel_sector, offset, todo, fragment_len;
501         size_t entry;
502
503         if (end_sector <= s->start || bi_sector >= s->end)
504                 return;
505         if (unlikely(bi_sector < s->start)) {
506                 rel_sector = 0;
507                 todo = end_sector - s->start;
508         } else {
509                 rel_sector = bi_sector - s->start;
510                 todo = end_sector - bi_sector;
511         }
512         if (unlikely(end_sector > s->end))
513                 todo -= (end_sector - s->end);
514
515         offset = dm_sector_div64(rel_sector, s->step);
516         entry = rel_sector;
517         do {
518                 if (WARN_ON_ONCE(entry >= s->n_entries)) {
519                         DMCRIT("Invalid area access in region id %d", s->id);
520                         return;
521                 }
522                 fragment_len = todo;
523                 if (fragment_len > s->step - offset)
524                         fragment_len = s->step - offset;
525                 dm_stat_for_entry(s, entry, bi_rw, fragment_len,
526                                   stats_aux->merged, end, duration);
527                 todo -= fragment_len;
528                 entry++;
529                 offset = 0;
530         } while (unlikely(todo != 0));
531 }
532
533 void dm_stats_account_io(struct dm_stats *stats, unsigned long bi_rw,
534                          sector_t bi_sector, unsigned bi_sectors, bool end,
535                          unsigned long duration, struct dm_stats_aux *stats_aux)
536 {
537         struct dm_stat *s;
538         sector_t end_sector;
539         struct dm_stats_last_position *last;
540
541         if (unlikely(!bi_sectors))
542                 return;
543
544         end_sector = bi_sector + bi_sectors;
545
546         if (!end) {
547                 /*
548                  * A race condition can at worst result in the merged flag being
549                  * misrepresented, so we don't have to disable preemption here.
550                  */
551                 last = raw_cpu_ptr(stats->last);
552                 stats_aux->merged =
553                         (bi_sector == (ACCESS_ONCE(last->last_sector) &&
554                                        ((bi_rw & (REQ_WRITE | REQ_DISCARD)) ==
555                                         (ACCESS_ONCE(last->last_rw) & (REQ_WRITE | REQ_DISCARD)))
556                                        ));
557                 ACCESS_ONCE(last->last_sector) = end_sector;
558                 ACCESS_ONCE(last->last_rw) = bi_rw;
559         }
560
561         rcu_read_lock();
562
563         list_for_each_entry_rcu(s, &stats->list, list_entry)
564                 __dm_stat_bio(s, bi_rw, bi_sector, end_sector, end, duration, stats_aux);
565
566         rcu_read_unlock();
567 }
568
569 static void __dm_stat_init_temporary_percpu_totals(struct dm_stat_shared *shared,
570                                                    struct dm_stat *s, size_t x)
571 {
572         int cpu;
573         struct dm_stat_percpu *p;
574
575         local_irq_disable();
576         p = &s->stat_percpu[smp_processor_id()][x];
577         dm_stat_round(shared, p);
578         local_irq_enable();
579
580         memset(&shared->tmp, 0, sizeof(shared->tmp));
581         for_each_possible_cpu(cpu) {
582                 p = &s->stat_percpu[cpu][x];
583                 shared->tmp.sectors[READ] += ACCESS_ONCE(p->sectors[READ]);
584                 shared->tmp.sectors[WRITE] += ACCESS_ONCE(p->sectors[WRITE]);
585                 shared->tmp.ios[READ] += ACCESS_ONCE(p->ios[READ]);
586                 shared->tmp.ios[WRITE] += ACCESS_ONCE(p->ios[WRITE]);
587                 shared->tmp.merges[READ] += ACCESS_ONCE(p->merges[READ]);
588                 shared->tmp.merges[WRITE] += ACCESS_ONCE(p->merges[WRITE]);
589                 shared->tmp.ticks[READ] += ACCESS_ONCE(p->ticks[READ]);
590                 shared->tmp.ticks[WRITE] += ACCESS_ONCE(p->ticks[WRITE]);
591                 shared->tmp.io_ticks[READ] += ACCESS_ONCE(p->io_ticks[READ]);
592                 shared->tmp.io_ticks[WRITE] += ACCESS_ONCE(p->io_ticks[WRITE]);
593                 shared->tmp.io_ticks_total += ACCESS_ONCE(p->io_ticks_total);
594                 shared->tmp.time_in_queue += ACCESS_ONCE(p->time_in_queue);
595         }
596 }
597
598 static void __dm_stat_clear(struct dm_stat *s, size_t idx_start, size_t idx_end,
599                             bool init_tmp_percpu_totals)
600 {
601         size_t x;
602         struct dm_stat_shared *shared;
603         struct dm_stat_percpu *p;
604
605         for (x = idx_start; x < idx_end; x++) {
606                 shared = &s->stat_shared[x];
607                 if (init_tmp_percpu_totals)
608                         __dm_stat_init_temporary_percpu_totals(shared, s, x);
609                 local_irq_disable();
610                 p = &s->stat_percpu[smp_processor_id()][x];
611                 p->sectors[READ] -= shared->tmp.sectors[READ];
612                 p->sectors[WRITE] -= shared->tmp.sectors[WRITE];
613                 p->ios[READ] -= shared->tmp.ios[READ];
614                 p->ios[WRITE] -= shared->tmp.ios[WRITE];
615                 p->merges[READ] -= shared->tmp.merges[READ];
616                 p->merges[WRITE] -= shared->tmp.merges[WRITE];
617                 p->ticks[READ] -= shared->tmp.ticks[READ];
618                 p->ticks[WRITE] -= shared->tmp.ticks[WRITE];
619                 p->io_ticks[READ] -= shared->tmp.io_ticks[READ];
620                 p->io_ticks[WRITE] -= shared->tmp.io_ticks[WRITE];
621                 p->io_ticks_total -= shared->tmp.io_ticks_total;
622                 p->time_in_queue -= shared->tmp.time_in_queue;
623                 local_irq_enable();
624         }
625 }
626
627 static int dm_stats_clear(struct dm_stats *stats, int id)
628 {
629         struct dm_stat *s;
630
631         mutex_lock(&stats->mutex);
632
633         s = __dm_stats_find(stats, id);
634         if (!s) {
635                 mutex_unlock(&stats->mutex);
636                 return -ENOENT;
637         }
638
639         __dm_stat_clear(s, 0, s->n_entries, true);
640
641         mutex_unlock(&stats->mutex);
642
643         return 1;
644 }
645
646 /*
647  * This is like jiffies_to_msec, but works for 64-bit values.
648  */
649 static unsigned long long dm_jiffies_to_msec64(unsigned long long j)
650 {
651         unsigned long long result = 0;
652         unsigned mult;
653
654         if (j)
655                 result = jiffies_to_msecs(j & 0x3fffff);
656         if (j >= 1 << 22) {
657                 mult = jiffies_to_msecs(1 << 22);
658                 result += (unsigned long long)mult * (unsigned long long)jiffies_to_msecs((j >> 22) & 0x3fffff);
659         }
660         if (j >= 1ULL << 44)
661                 result += (unsigned long long)mult * (unsigned long long)mult * (unsigned long long)jiffies_to_msecs(j >> 44);
662
663         return result;
664 }
665
666 static int dm_stats_print(struct dm_stats *stats, int id,
667                           size_t idx_start, size_t idx_len,
668                           bool clear, char *result, unsigned maxlen)
669 {
670         unsigned sz = 0;
671         struct dm_stat *s;
672         size_t x;
673         sector_t start, end, step;
674         size_t idx_end;
675         struct dm_stat_shared *shared;
676
677         /*
678          * Output format:
679          *   <start_sector>+<length> counters
680          */
681
682         mutex_lock(&stats->mutex);
683
684         s = __dm_stats_find(stats, id);
685         if (!s) {
686                 mutex_unlock(&stats->mutex);
687                 return -ENOENT;
688         }
689
690         idx_end = idx_start + idx_len;
691         if (idx_end < idx_start ||
692             idx_end > s->n_entries)
693                 idx_end = s->n_entries;
694
695         if (idx_start > idx_end)
696                 idx_start = idx_end;
697
698         step = s->step;
699         start = s->start + (step * idx_start);
700
701         for (x = idx_start; x < idx_end; x++, start = end) {
702                 shared = &s->stat_shared[x];
703                 end = start + step;
704                 if (unlikely(end > s->end))
705                         end = s->end;
706
707                 __dm_stat_init_temporary_percpu_totals(shared, s, x);
708
709                 DMEMIT("%llu+%llu %llu %llu %llu %llu %llu %llu %llu %llu %d %llu %llu %llu %llu\n",
710                        (unsigned long long)start,
711                        (unsigned long long)step,
712                        shared->tmp.ios[READ],
713                        shared->tmp.merges[READ],
714                        shared->tmp.sectors[READ],
715                        dm_jiffies_to_msec64(shared->tmp.ticks[READ]),
716                        shared->tmp.ios[WRITE],
717                        shared->tmp.merges[WRITE],
718                        shared->tmp.sectors[WRITE],
719                        dm_jiffies_to_msec64(shared->tmp.ticks[WRITE]),
720                        dm_stat_in_flight(shared),
721                        dm_jiffies_to_msec64(shared->tmp.io_ticks_total),
722                        dm_jiffies_to_msec64(shared->tmp.time_in_queue),
723                        dm_jiffies_to_msec64(shared->tmp.io_ticks[READ]),
724                        dm_jiffies_to_msec64(shared->tmp.io_ticks[WRITE]));
725
726                 if (unlikely(sz + 1 >= maxlen))
727                         goto buffer_overflow;
728         }
729
730         if (clear)
731                 __dm_stat_clear(s, idx_start, idx_end, false);
732
733 buffer_overflow:
734         mutex_unlock(&stats->mutex);
735
736         return 1;
737 }
738
739 static int dm_stats_set_aux(struct dm_stats *stats, int id, const char *aux_data)
740 {
741         struct dm_stat *s;
742         const char *new_aux_data;
743
744         mutex_lock(&stats->mutex);
745
746         s = __dm_stats_find(stats, id);
747         if (!s) {
748                 mutex_unlock(&stats->mutex);
749                 return -ENOENT;
750         }
751
752         new_aux_data = kstrdup(aux_data, GFP_KERNEL);
753         if (!new_aux_data) {
754                 mutex_unlock(&stats->mutex);
755                 return -ENOMEM;
756         }
757
758         kfree(s->aux_data);
759         s->aux_data = new_aux_data;
760
761         mutex_unlock(&stats->mutex);
762
763         return 0;
764 }
765
766 static int message_stats_create(struct mapped_device *md,
767                                 unsigned argc, char **argv,
768                                 char *result, unsigned maxlen)
769 {
770         int id;
771         char dummy;
772         unsigned long long start, end, len, step;
773         unsigned divisor;
774         const char *program_id, *aux_data;
775
776         /*
777          * Input format:
778          *   <range> <step> [<program_id> [<aux_data>]]
779          */
780
781         if (argc < 3 || argc > 5)
782                 return -EINVAL;
783
784         if (!strcmp(argv[1], "-")) {
785                 start = 0;
786                 len = dm_get_size(md);
787                 if (!len)
788                         len = 1;
789         } else if (sscanf(argv[1], "%llu+%llu%c", &start, &len, &dummy) != 2 ||
790                    start != (sector_t)start || len != (sector_t)len)
791                 return -EINVAL;
792
793         end = start + len;
794         if (start >= end)
795                 return -EINVAL;
796
797         if (sscanf(argv[2], "/%u%c", &divisor, &dummy) == 1) {
798                 step = end - start;
799                 if (do_div(step, divisor))
800                         step++;
801                 if (!step)
802                         step = 1;
803         } else if (sscanf(argv[2], "%llu%c", &step, &dummy) != 1 ||
804                    step != (sector_t)step || !step)
805                 return -EINVAL;
806
807         program_id = "-";
808         aux_data = "-";
809
810         if (argc > 3)
811                 program_id = argv[3];
812
813         if (argc > 4)
814                 aux_data = argv[4];
815
816         /*
817          * If a buffer overflow happens after we created the region,
818          * it's too late (the userspace would retry with a larger
819          * buffer, but the region id that caused the overflow is already
820          * leaked).  So we must detect buffer overflow in advance.
821          */
822         snprintf(result, maxlen, "%d", INT_MAX);
823         if (dm_message_test_buffer_overflow(result, maxlen))
824                 return 1;
825
826         id = dm_stats_create(dm_get_stats(md), start, end, step, program_id, aux_data,
827                              dm_internal_suspend_fast, dm_internal_resume_fast, md);
828         if (id < 0)
829                 return id;
830
831         snprintf(result, maxlen, "%d", id);
832
833         return 1;
834 }
835
836 static int message_stats_delete(struct mapped_device *md,
837                                 unsigned argc, char **argv)
838 {
839         int id;
840         char dummy;
841
842         if (argc != 2)
843                 return -EINVAL;
844
845         if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
846                 return -EINVAL;
847
848         return dm_stats_delete(dm_get_stats(md), id);
849 }
850
851 static int message_stats_clear(struct mapped_device *md,
852                                unsigned argc, char **argv)
853 {
854         int id;
855         char dummy;
856
857         if (argc != 2)
858                 return -EINVAL;
859
860         if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
861                 return -EINVAL;
862
863         return dm_stats_clear(dm_get_stats(md), id);
864 }
865
866 static int message_stats_list(struct mapped_device *md,
867                               unsigned argc, char **argv,
868                               char *result, unsigned maxlen)
869 {
870         int r;
871         const char *program = NULL;
872
873         if (argc < 1 || argc > 2)
874                 return -EINVAL;
875
876         if (argc > 1) {
877                 program = kstrdup(argv[1], GFP_KERNEL);
878                 if (!program)
879                         return -ENOMEM;
880         }
881
882         r = dm_stats_list(dm_get_stats(md), program, result, maxlen);
883
884         kfree(program);
885
886         return r;
887 }
888
889 static int message_stats_print(struct mapped_device *md,
890                                unsigned argc, char **argv, bool clear,
891                                char *result, unsigned maxlen)
892 {
893         int id;
894         char dummy;
895         unsigned long idx_start = 0, idx_len = ULONG_MAX;
896
897         if (argc != 2 && argc != 4)
898                 return -EINVAL;
899
900         if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
901                 return -EINVAL;
902
903         if (argc > 3) {
904                 if (strcmp(argv[2], "-") &&
905                     sscanf(argv[2], "%lu%c", &idx_start, &dummy) != 1)
906                         return -EINVAL;
907                 if (strcmp(argv[3], "-") &&
908                     sscanf(argv[3], "%lu%c", &idx_len, &dummy) != 1)
909                         return -EINVAL;
910         }
911
912         return dm_stats_print(dm_get_stats(md), id, idx_start, idx_len, clear,
913                               result, maxlen);
914 }
915
916 static int message_stats_set_aux(struct mapped_device *md,
917                                  unsigned argc, char **argv)
918 {
919         int id;
920         char dummy;
921
922         if (argc != 3)
923                 return -EINVAL;
924
925         if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
926                 return -EINVAL;
927
928         return dm_stats_set_aux(dm_get_stats(md), id, argv[2]);
929 }
930
931 int dm_stats_message(struct mapped_device *md, unsigned argc, char **argv,
932                      char *result, unsigned maxlen)
933 {
934         int r;
935
936         if (dm_request_based(md)) {
937                 DMWARN("Statistics are only supported for bio-based devices");
938                 return -EOPNOTSUPP;
939         }
940
941         /* All messages here must start with '@' */
942         if (!strcasecmp(argv[0], "@stats_create"))
943                 r = message_stats_create(md, argc, argv, result, maxlen);
944         else if (!strcasecmp(argv[0], "@stats_delete"))
945                 r = message_stats_delete(md, argc, argv);
946         else if (!strcasecmp(argv[0], "@stats_clear"))
947                 r = message_stats_clear(md, argc, argv);
948         else if (!strcasecmp(argv[0], "@stats_list"))
949                 r = message_stats_list(md, argc, argv, result, maxlen);
950         else if (!strcasecmp(argv[0], "@stats_print"))
951                 r = message_stats_print(md, argc, argv, false, result, maxlen);
952         else if (!strcasecmp(argv[0], "@stats_print_clear"))
953                 r = message_stats_print(md, argc, argv, true, result, maxlen);
954         else if (!strcasecmp(argv[0], "@stats_set_aux"))
955                 r = message_stats_set_aux(md, argc, argv);
956         else
957                 return 2; /* this wasn't a stats message */
958
959         if (r == -EINVAL)
960                 DMWARN("Invalid parameters for message %s", argv[0]);
961
962         return r;
963 }
964
965 int __init dm_statistics_init(void)
966 {
967         shared_memory_amount = 0;
968         dm_stat_need_rcu_barrier = 0;
969         return 0;
970 }
971
972 void dm_statistics_exit(void)
973 {
974         if (dm_stat_need_rcu_barrier)
975                 rcu_barrier();
976         if (WARN_ON(shared_memory_amount))
977                 DMCRIT("shared_memory_amount leaked: %lu", shared_memory_amount);
978 }
979
980 module_param_named(stats_current_allocated_bytes, shared_memory_amount, ulong, S_IRUGO);
981 MODULE_PARM_DESC(stats_current_allocated_bytes, "Memory currently used by statistics");