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1// SPDX-License-Identifier: GPL-2.0
2#include <linux/errno.h>
3#include <linux/numa.h>
4#include <linux/slab.h>
5#include <linux/rculist.h>
6#include <linux/threads.h>
7#include <linux/preempt.h>
8#include <linux/irqflags.h>
9#include <linux/vmalloc.h>
10#include <linux/mm.h>
11#include <linux/module.h>
12#include <linux/device-mapper.h>
13
14#include "dm-core.h"
15#include "dm-stats.h"
16
17#define DM_MSG_PREFIX "stats"
18
19static int dm_stat_need_rcu_barrier;
20
21/*
22 * Using 64-bit values to avoid overflow (which is a
23 * problem that block/genhd.c's IO accounting has).
24 */
25struct dm_stat_percpu {
26 unsigned long long sectors[2];
27 unsigned long long ios[2];
28 unsigned long long merges[2];
29 unsigned long long ticks[2];
30 unsigned long long io_ticks[2];
31 unsigned long long io_ticks_total;
32 unsigned long long time_in_queue;
33 unsigned long long *histogram;
34};
35
36struct dm_stat_shared {
37 atomic_t in_flight[2];
38 unsigned long long stamp;
39 struct dm_stat_percpu tmp;
40};
41
42struct dm_stat {
43 struct list_head list_entry;
44 int id;
45 unsigned stat_flags;
46 size_t n_entries;
47 sector_t start;
48 sector_t end;
49 sector_t step;
50 unsigned n_histogram_entries;
51 unsigned long long *histogram_boundaries;
52 const char *program_id;
53 const char *aux_data;
54 struct rcu_head rcu_head;
55 size_t shared_alloc_size;
56 size_t percpu_alloc_size;
57 size_t histogram_alloc_size;
58 struct dm_stat_percpu *stat_percpu[NR_CPUS];
59 struct dm_stat_shared stat_shared[];
60};
61
62#define STAT_PRECISE_TIMESTAMPS 1
63
64struct dm_stats_last_position {
65 sector_t last_sector;
66 unsigned last_rw;
67};
68
69/*
70 * A typo on the command line could possibly make the kernel run out of memory
71 * and crash. To prevent the crash we account all used memory. We fail if we
72 * exhaust 1/4 of all memory or 1/2 of vmalloc space.
73 */
74#define DM_STATS_MEMORY_FACTOR 4
75#define DM_STATS_VMALLOC_FACTOR 2
76
77static DEFINE_SPINLOCK(shared_memory_lock);
78
79static unsigned long shared_memory_amount;
80
81static bool __check_shared_memory(size_t alloc_size)
82{
83 size_t a;
84
85 a = shared_memory_amount + alloc_size;
86 if (a < shared_memory_amount)
87 return false;
88 if (a >> PAGE_SHIFT > totalram_pages() / DM_STATS_MEMORY_FACTOR)
89 return false;
90#ifdef CONFIG_MMU
91 if (a > (VMALLOC_END - VMALLOC_START) / DM_STATS_VMALLOC_FACTOR)
92 return false;
93#endif
94 return true;
95}
96
97static bool check_shared_memory(size_t alloc_size)
98{
99 bool ret;
100
101 spin_lock_irq(&shared_memory_lock);
102
103 ret = __check_shared_memory(alloc_size);
104
105 spin_unlock_irq(&shared_memory_lock);
106
107 return ret;
108}
109
110static bool claim_shared_memory(size_t alloc_size)
111{
112 spin_lock_irq(&shared_memory_lock);
113
114 if (!__check_shared_memory(alloc_size)) {
115 spin_unlock_irq(&shared_memory_lock);
116 return false;
117 }
118
119 shared_memory_amount += alloc_size;
120
121 spin_unlock_irq(&shared_memory_lock);
122
123 return true;
124}
125
126static void free_shared_memory(size_t alloc_size)
127{
128 unsigned long flags;
129
130 spin_lock_irqsave(&shared_memory_lock, flags);
131
132 if (WARN_ON_ONCE(shared_memory_amount < alloc_size)) {
133 spin_unlock_irqrestore(&shared_memory_lock, flags);
134 DMCRIT("Memory usage accounting bug.");
135 return;
136 }
137
138 shared_memory_amount -= alloc_size;
139
140 spin_unlock_irqrestore(&shared_memory_lock, flags);
141}
142
143static void *dm_kvzalloc(size_t alloc_size, int node)
144{
145 void *p;
146
147 if (!claim_shared_memory(alloc_size))
148 return NULL;
149
150 p = kvzalloc_node(alloc_size, GFP_KERNEL | __GFP_NOMEMALLOC, node);
151 if (p)
152 return p;
153
154 free_shared_memory(alloc_size);
155
156 return NULL;
157}
158
159static void dm_kvfree(void *ptr, size_t alloc_size)
160{
161 if (!ptr)
162 return;
163
164 free_shared_memory(alloc_size);
165
166 kvfree(ptr);
167}
168
169static 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->histogram_boundaries);
175 kfree(s->program_id);
176 kfree(s->aux_data);
177 for_each_possible_cpu(cpu) {
178 dm_kvfree(s->stat_percpu[cpu][0].histogram, s->histogram_alloc_size);
179 dm_kvfree(s->stat_percpu[cpu], s->percpu_alloc_size);
180 }
181 dm_kvfree(s->stat_shared[0].tmp.histogram, s->histogram_alloc_size);
182 dm_kvfree(s, s->shared_alloc_size);
183}
184
185static int dm_stat_in_flight(struct dm_stat_shared *shared)
186{
187 return atomic_read(&shared->in_flight[READ]) +
188 atomic_read(&shared->in_flight[WRITE]);
189}
190
191void dm_stats_init(struct dm_stats *stats)
192{
193 int cpu;
194 struct dm_stats_last_position *last;
195
196 mutex_init(&stats->mutex);
197 INIT_LIST_HEAD(&stats->list);
198 stats->precise_timestamps = false;
199 stats->last = alloc_percpu(struct dm_stats_last_position);
200 for_each_possible_cpu(cpu) {
201 last = per_cpu_ptr(stats->last, cpu);
202 last->last_sector = (sector_t)ULLONG_MAX;
203 last->last_rw = UINT_MAX;
204 }
205}
206
207void dm_stats_cleanup(struct dm_stats *stats)
208{
209 size_t ni;
210 struct dm_stat *s;
211 struct dm_stat_shared *shared;
212
213 while (!list_empty(&stats->list)) {
214 s = container_of(stats->list.next, struct dm_stat, list_entry);
215 list_del(&s->list_entry);
216 for (ni = 0; ni < s->n_entries; ni++) {
217 shared = &s->stat_shared[ni];
218 if (WARN_ON(dm_stat_in_flight(shared))) {
219 DMCRIT("leaked in-flight counter at index %lu "
220 "(start %llu, end %llu, step %llu): reads %d, writes %d",
221 (unsigned long)ni,
222 (unsigned long long)s->start,
223 (unsigned long long)s->end,
224 (unsigned long long)s->step,
225 atomic_read(&shared->in_flight[READ]),
226 atomic_read(&shared->in_flight[WRITE]));
227 }
228 cond_resched();
229 }
230 dm_stat_free(&s->rcu_head);
231 }
232 free_percpu(stats->last);
233 mutex_destroy(&stats->mutex);
234}
235
236static void dm_stats_recalc_precise_timestamps(struct dm_stats *stats)
237{
238 struct list_head *l;
239 struct dm_stat *tmp_s;
240 bool precise_timestamps = false;
241
242 list_for_each(l, &stats->list) {
243 tmp_s = container_of(l, struct dm_stat, list_entry);
244 if (tmp_s->stat_flags & STAT_PRECISE_TIMESTAMPS) {
245 precise_timestamps = true;
246 break;
247 }
248 }
249 stats->precise_timestamps = precise_timestamps;
250}
251
252static int dm_stats_create(struct dm_stats *stats, sector_t start, sector_t end,
253 sector_t step, unsigned stat_flags,
254 unsigned n_histogram_entries,
255 unsigned long long *histogram_boundaries,
256 const char *program_id, const char *aux_data,
257 void (*suspend_callback)(struct mapped_device *),
258 void (*resume_callback)(struct mapped_device *),
259 struct mapped_device *md)
260{
261 struct list_head *l;
262 struct dm_stat *s, *tmp_s;
263 sector_t n_entries;
264 size_t ni;
265 size_t shared_alloc_size;
266 size_t percpu_alloc_size;
267 size_t histogram_alloc_size;
268 struct dm_stat_percpu *p;
269 int cpu;
270 int ret_id;
271 int r;
272
273 if (end < start || !step)
274 return -EINVAL;
275
276 n_entries = end - start;
277 if (dm_sector_div64(n_entries, step))
278 n_entries++;
279
280 if (n_entries != (size_t)n_entries || !(size_t)(n_entries + 1))
281 return -EOVERFLOW;
282
283 shared_alloc_size = struct_size(s, stat_shared, n_entries);
284 if ((shared_alloc_size - sizeof(struct dm_stat)) / sizeof(struct dm_stat_shared) != n_entries)
285 return -EOVERFLOW;
286
287 percpu_alloc_size = (size_t)n_entries * sizeof(struct dm_stat_percpu);
288 if (percpu_alloc_size / sizeof(struct dm_stat_percpu) != n_entries)
289 return -EOVERFLOW;
290
291 histogram_alloc_size = (n_histogram_entries + 1) * (size_t)n_entries * sizeof(unsigned long long);
292 if (histogram_alloc_size / (n_histogram_entries + 1) != (size_t)n_entries * sizeof(unsigned long long))
293 return -EOVERFLOW;
294
295 if (!check_shared_memory(shared_alloc_size + histogram_alloc_size +
296 num_possible_cpus() * (percpu_alloc_size + histogram_alloc_size)))
297 return -ENOMEM;
298
299 s = dm_kvzalloc(shared_alloc_size, NUMA_NO_NODE);
300 if (!s)
301 return -ENOMEM;
302
303 s->stat_flags = stat_flags;
304 s->n_entries = n_entries;
305 s->start = start;
306 s->end = end;
307 s->step = step;
308 s->shared_alloc_size = shared_alloc_size;
309 s->percpu_alloc_size = percpu_alloc_size;
310 s->histogram_alloc_size = histogram_alloc_size;
311
312 s->n_histogram_entries = n_histogram_entries;
313 s->histogram_boundaries = kmemdup(histogram_boundaries,
314 s->n_histogram_entries * sizeof(unsigned long long), GFP_KERNEL);
315 if (!s->histogram_boundaries) {
316 r = -ENOMEM;
317 goto out;
318 }
319
320 s->program_id = kstrdup(program_id, GFP_KERNEL);
321 if (!s->program_id) {
322 r = -ENOMEM;
323 goto out;
324 }
325 s->aux_data = kstrdup(aux_data, GFP_KERNEL);
326 if (!s->aux_data) {
327 r = -ENOMEM;
328 goto out;
329 }
330
331 for (ni = 0; ni < n_entries; ni++) {
332 atomic_set(&s->stat_shared[ni].in_flight[READ], 0);
333 atomic_set(&s->stat_shared[ni].in_flight[WRITE], 0);
334 cond_resched();
335 }
336
337 if (s->n_histogram_entries) {
338 unsigned long long *hi;
339 hi = dm_kvzalloc(s->histogram_alloc_size, NUMA_NO_NODE);
340 if (!hi) {
341 r = -ENOMEM;
342 goto out;
343 }
344 for (ni = 0; ni < n_entries; ni++) {
345 s->stat_shared[ni].tmp.histogram = hi;
346 hi += s->n_histogram_entries + 1;
347 cond_resched();
348 }
349 }
350
351 for_each_possible_cpu(cpu) {
352 p = dm_kvzalloc(percpu_alloc_size, cpu_to_node(cpu));
353 if (!p) {
354 r = -ENOMEM;
355 goto out;
356 }
357 s->stat_percpu[cpu] = p;
358 if (s->n_histogram_entries) {
359 unsigned long long *hi;
360 hi = dm_kvzalloc(s->histogram_alloc_size, cpu_to_node(cpu));
361 if (!hi) {
362 r = -ENOMEM;
363 goto out;
364 }
365 for (ni = 0; ni < n_entries; ni++) {
366 p[ni].histogram = hi;
367 hi += s->n_histogram_entries + 1;
368 cond_resched();
369 }
370 }
371 }
372
373 /*
374 * Suspend/resume to make sure there is no i/o in flight,
375 * so that newly created statistics will be exact.
376 *
377 * (note: we couldn't suspend earlier because we must not
378 * allocate memory while suspended)
379 */
380 suspend_callback(md);
381
382 mutex_lock(&stats->mutex);
383 s->id = 0;
384 list_for_each(l, &stats->list) {
385 tmp_s = container_of(l, struct dm_stat, list_entry);
386 if (WARN_ON(tmp_s->id < s->id)) {
387 r = -EINVAL;
388 goto out_unlock_resume;
389 }
390 if (tmp_s->id > s->id)
391 break;
392 if (unlikely(s->id == INT_MAX)) {
393 r = -ENFILE;
394 goto out_unlock_resume;
395 }
396 s->id++;
397 }
398 ret_id = s->id;
399 list_add_tail_rcu(&s->list_entry, l);
400
401 dm_stats_recalc_precise_timestamps(stats);
402
403 if (!static_key_enabled(&stats_enabled.key))
404 static_branch_enable(&stats_enabled);
405
406 mutex_unlock(&stats->mutex);
407
408 resume_callback(md);
409
410 return ret_id;
411
412out_unlock_resume:
413 mutex_unlock(&stats->mutex);
414 resume_callback(md);
415out:
416 dm_stat_free(&s->rcu_head);
417 return r;
418}
419
420static struct dm_stat *__dm_stats_find(struct dm_stats *stats, int id)
421{
422 struct dm_stat *s;
423
424 list_for_each_entry(s, &stats->list, list_entry) {
425 if (s->id > id)
426 break;
427 if (s->id == id)
428 return s;
429 }
430
431 return NULL;
432}
433
434static int dm_stats_delete(struct dm_stats *stats, int id)
435{
436 struct dm_stat *s;
437 int cpu;
438
439 mutex_lock(&stats->mutex);
440
441 s = __dm_stats_find(stats, id);
442 if (!s) {
443 mutex_unlock(&stats->mutex);
444 return -ENOENT;
445 }
446
447 list_del_rcu(&s->list_entry);
448
449 dm_stats_recalc_precise_timestamps(stats);
450
451 mutex_unlock(&stats->mutex);
452
453 /*
454 * vfree can't be called from RCU callback
455 */
456 for_each_possible_cpu(cpu)
457 if (is_vmalloc_addr(s->stat_percpu) ||
458 is_vmalloc_addr(s->stat_percpu[cpu][0].histogram))
459 goto do_sync_free;
460 if (is_vmalloc_addr(s) ||
461 is_vmalloc_addr(s->stat_shared[0].tmp.histogram)) {
462do_sync_free:
463 synchronize_rcu_expedited();
464 dm_stat_free(&s->rcu_head);
465 } else {
466 WRITE_ONCE(dm_stat_need_rcu_barrier, 1);
467 call_rcu(&s->rcu_head, dm_stat_free);
468 }
469 return 0;
470}
471
472static int dm_stats_list(struct dm_stats *stats, const char *program,
473 char *result, unsigned maxlen)
474{
475 struct dm_stat *s;
476 sector_t len;
477 unsigned sz = 0;
478
479 /*
480 * Output format:
481 * <region_id>: <start_sector>+<length> <step> <program_id> <aux_data>
482 */
483
484 mutex_lock(&stats->mutex);
485 list_for_each_entry(s, &stats->list, list_entry) {
486 if (!program || !strcmp(program, s->program_id)) {
487 len = s->end - s->start;
488 DMEMIT("%d: %llu+%llu %llu %s %s", s->id,
489 (unsigned long long)s->start,
490 (unsigned long long)len,
491 (unsigned long long)s->step,
492 s->program_id,
493 s->aux_data);
494 if (s->stat_flags & STAT_PRECISE_TIMESTAMPS)
495 DMEMIT(" precise_timestamps");
496 if (s->n_histogram_entries) {
497 unsigned i;
498 DMEMIT(" histogram:");
499 for (i = 0; i < s->n_histogram_entries; i++) {
500 if (i)
501 DMEMIT(",");
502 DMEMIT("%llu", s->histogram_boundaries[i]);
503 }
504 }
505 DMEMIT("\n");
506 }
507 cond_resched();
508 }
509 mutex_unlock(&stats->mutex);
510
511 return 1;
512}
513
514static void dm_stat_round(struct dm_stat *s, struct dm_stat_shared *shared,
515 struct dm_stat_percpu *p)
516{
517 /*
518 * This is racy, but so is part_round_stats_single.
519 */
520 unsigned long long now, difference;
521 unsigned in_flight_read, in_flight_write;
522
523 if (likely(!(s->stat_flags & STAT_PRECISE_TIMESTAMPS)))
524 now = jiffies;
525 else
526 now = ktime_to_ns(ktime_get());
527
528 difference = now - shared->stamp;
529 if (!difference)
530 return;
531
532 in_flight_read = (unsigned)atomic_read(&shared->in_flight[READ]);
533 in_flight_write = (unsigned)atomic_read(&shared->in_flight[WRITE]);
534 if (in_flight_read)
535 p->io_ticks[READ] += difference;
536 if (in_flight_write)
537 p->io_ticks[WRITE] += difference;
538 if (in_flight_read + in_flight_write) {
539 p->io_ticks_total += difference;
540 p->time_in_queue += (in_flight_read + in_flight_write) * difference;
541 }
542 shared->stamp = now;
543}
544
545static void dm_stat_for_entry(struct dm_stat *s, size_t entry,
546 int idx, sector_t len,
547 struct dm_stats_aux *stats_aux, bool end,
548 unsigned long duration_jiffies)
549{
550 struct dm_stat_shared *shared = &s->stat_shared[entry];
551 struct dm_stat_percpu *p;
552
553 /*
554 * For strict correctness we should use local_irq_save/restore
555 * instead of preempt_disable/enable.
556 *
557 * preempt_disable/enable is racy if the driver finishes bios
558 * from non-interrupt context as well as from interrupt context
559 * or from more different interrupts.
560 *
561 * On 64-bit architectures the race only results in not counting some
562 * events, so it is acceptable. On 32-bit architectures the race could
563 * cause the counter going off by 2^32, so we need to do proper locking
564 * there.
565 *
566 * part_stat_lock()/part_stat_unlock() have this race too.
567 */
568#if BITS_PER_LONG == 32
569 unsigned long flags;
570 local_irq_save(flags);
571#else
572 preempt_disable();
573#endif
574 p = &s->stat_percpu[smp_processor_id()][entry];
575
576 if (!end) {
577 dm_stat_round(s, shared, p);
578 atomic_inc(&shared->in_flight[idx]);
579 } else {
580 unsigned long long duration;
581 dm_stat_round(s, shared, p);
582 atomic_dec(&shared->in_flight[idx]);
583 p->sectors[idx] += len;
584 p->ios[idx] += 1;
585 p->merges[idx] += stats_aux->merged;
586 if (!(s->stat_flags & STAT_PRECISE_TIMESTAMPS)) {
587 p->ticks[idx] += duration_jiffies;
588 duration = jiffies_to_msecs(duration_jiffies);
589 } else {
590 p->ticks[idx] += stats_aux->duration_ns;
591 duration = stats_aux->duration_ns;
592 }
593 if (s->n_histogram_entries) {
594 unsigned lo = 0, hi = s->n_histogram_entries + 1;
595 while (lo + 1 < hi) {
596 unsigned mid = (lo + hi) / 2;
597 if (s->histogram_boundaries[mid - 1] > duration) {
598 hi = mid;
599 } else {
600 lo = mid;
601 }
602
603 }
604 p->histogram[lo]++;
605 }
606 }
607
608#if BITS_PER_LONG == 32
609 local_irq_restore(flags);
610#else
611 preempt_enable();
612#endif
613}
614
615static void __dm_stat_bio(struct dm_stat *s, int bi_rw,
616 sector_t bi_sector, sector_t end_sector,
617 bool end, unsigned long duration_jiffies,
618 struct dm_stats_aux *stats_aux)
619{
620 sector_t rel_sector, offset, todo, fragment_len;
621 size_t entry;
622
623 if (end_sector <= s->start || bi_sector >= s->end)
624 return;
625 if (unlikely(bi_sector < s->start)) {
626 rel_sector = 0;
627 todo = end_sector - s->start;
628 } else {
629 rel_sector = bi_sector - s->start;
630 todo = end_sector - bi_sector;
631 }
632 if (unlikely(end_sector > s->end))
633 todo -= (end_sector - s->end);
634
635 offset = dm_sector_div64(rel_sector, s->step);
636 entry = rel_sector;
637 do {
638 if (WARN_ON_ONCE(entry >= s->n_entries)) {
639 DMCRIT("Invalid area access in region id %d", s->id);
640 return;
641 }
642 fragment_len = todo;
643 if (fragment_len > s->step - offset)
644 fragment_len = s->step - offset;
645 dm_stat_for_entry(s, entry, bi_rw, fragment_len,
646 stats_aux, end, duration_jiffies);
647 todo -= fragment_len;
648 entry++;
649 offset = 0;
650 } while (unlikely(todo != 0));
651}
652
653void dm_stats_account_io(struct dm_stats *stats, unsigned long bi_rw,
654 sector_t bi_sector, unsigned bi_sectors, bool end,
655 unsigned long start_time,
656 struct dm_stats_aux *stats_aux)
657{
658 struct dm_stat *s;
659 sector_t end_sector;
660 struct dm_stats_last_position *last;
661 bool got_precise_time;
662 unsigned long duration_jiffies = 0;
663
664 if (unlikely(!bi_sectors))
665 return;
666
667 end_sector = bi_sector + bi_sectors;
668
669 if (!end) {
670 /*
671 * A race condition can at worst result in the merged flag being
672 * misrepresented, so we don't have to disable preemption here.
673 */
674 last = raw_cpu_ptr(stats->last);
675 stats_aux->merged =
676 (bi_sector == (READ_ONCE(last->last_sector) &&
677 ((bi_rw == WRITE) ==
678 (READ_ONCE(last->last_rw) == WRITE))
679 ));
680 WRITE_ONCE(last->last_sector, end_sector);
681 WRITE_ONCE(last->last_rw, bi_rw);
682 } else
683 duration_jiffies = jiffies - start_time;
684
685 rcu_read_lock();
686
687 got_precise_time = false;
688 list_for_each_entry_rcu(s, &stats->list, list_entry) {
689 if (s->stat_flags & STAT_PRECISE_TIMESTAMPS && !got_precise_time) {
690 /* start (!end) duration_ns is set by DM core's alloc_io() */
691 if (end)
692 stats_aux->duration_ns = ktime_to_ns(ktime_get()) - stats_aux->duration_ns;
693 got_precise_time = true;
694 }
695 __dm_stat_bio(s, bi_rw, bi_sector, end_sector, end, duration_jiffies, stats_aux);
696 }
697
698 rcu_read_unlock();
699}
700
701static void __dm_stat_init_temporary_percpu_totals(struct dm_stat_shared *shared,
702 struct dm_stat *s, size_t x)
703{
704 int cpu;
705 struct dm_stat_percpu *p;
706
707 local_irq_disable();
708 p = &s->stat_percpu[smp_processor_id()][x];
709 dm_stat_round(s, shared, p);
710 local_irq_enable();
711
712 shared->tmp.sectors[READ] = 0;
713 shared->tmp.sectors[WRITE] = 0;
714 shared->tmp.ios[READ] = 0;
715 shared->tmp.ios[WRITE] = 0;
716 shared->tmp.merges[READ] = 0;
717 shared->tmp.merges[WRITE] = 0;
718 shared->tmp.ticks[READ] = 0;
719 shared->tmp.ticks[WRITE] = 0;
720 shared->tmp.io_ticks[READ] = 0;
721 shared->tmp.io_ticks[WRITE] = 0;
722 shared->tmp.io_ticks_total = 0;
723 shared->tmp.time_in_queue = 0;
724
725 if (s->n_histogram_entries)
726 memset(shared->tmp.histogram, 0, (s->n_histogram_entries + 1) * sizeof(unsigned long long));
727
728 for_each_possible_cpu(cpu) {
729 p = &s->stat_percpu[cpu][x];
730 shared->tmp.sectors[READ] += READ_ONCE(p->sectors[READ]);
731 shared->tmp.sectors[WRITE] += READ_ONCE(p->sectors[WRITE]);
732 shared->tmp.ios[READ] += READ_ONCE(p->ios[READ]);
733 shared->tmp.ios[WRITE] += READ_ONCE(p->ios[WRITE]);
734 shared->tmp.merges[READ] += READ_ONCE(p->merges[READ]);
735 shared->tmp.merges[WRITE] += READ_ONCE(p->merges[WRITE]);
736 shared->tmp.ticks[READ] += READ_ONCE(p->ticks[READ]);
737 shared->tmp.ticks[WRITE] += READ_ONCE(p->ticks[WRITE]);
738 shared->tmp.io_ticks[READ] += READ_ONCE(p->io_ticks[READ]);
739 shared->tmp.io_ticks[WRITE] += READ_ONCE(p->io_ticks[WRITE]);
740 shared->tmp.io_ticks_total += READ_ONCE(p->io_ticks_total);
741 shared->tmp.time_in_queue += READ_ONCE(p->time_in_queue);
742 if (s->n_histogram_entries) {
743 unsigned i;
744 for (i = 0; i < s->n_histogram_entries + 1; i++)
745 shared->tmp.histogram[i] += READ_ONCE(p->histogram[i]);
746 }
747 }
748}
749
750static void __dm_stat_clear(struct dm_stat *s, size_t idx_start, size_t idx_end,
751 bool init_tmp_percpu_totals)
752{
753 size_t x;
754 struct dm_stat_shared *shared;
755 struct dm_stat_percpu *p;
756
757 for (x = idx_start; x < idx_end; x++) {
758 shared = &s->stat_shared[x];
759 if (init_tmp_percpu_totals)
760 __dm_stat_init_temporary_percpu_totals(shared, s, x);
761 local_irq_disable();
762 p = &s->stat_percpu[smp_processor_id()][x];
763 p->sectors[READ] -= shared->tmp.sectors[READ];
764 p->sectors[WRITE] -= shared->tmp.sectors[WRITE];
765 p->ios[READ] -= shared->tmp.ios[READ];
766 p->ios[WRITE] -= shared->tmp.ios[WRITE];
767 p->merges[READ] -= shared->tmp.merges[READ];
768 p->merges[WRITE] -= shared->tmp.merges[WRITE];
769 p->ticks[READ] -= shared->tmp.ticks[READ];
770 p->ticks[WRITE] -= shared->tmp.ticks[WRITE];
771 p->io_ticks[READ] -= shared->tmp.io_ticks[READ];
772 p->io_ticks[WRITE] -= shared->tmp.io_ticks[WRITE];
773 p->io_ticks_total -= shared->tmp.io_ticks_total;
774 p->time_in_queue -= shared->tmp.time_in_queue;
775 local_irq_enable();
776 if (s->n_histogram_entries) {
777 unsigned i;
778 for (i = 0; i < s->n_histogram_entries + 1; i++) {
779 local_irq_disable();
780 p = &s->stat_percpu[smp_processor_id()][x];
781 p->histogram[i] -= shared->tmp.histogram[i];
782 local_irq_enable();
783 }
784 }
785 cond_resched();
786 }
787}
788
789static int dm_stats_clear(struct dm_stats *stats, int id)
790{
791 struct dm_stat *s;
792
793 mutex_lock(&stats->mutex);
794
795 s = __dm_stats_find(stats, id);
796 if (!s) {
797 mutex_unlock(&stats->mutex);
798 return -ENOENT;
799 }
800
801 __dm_stat_clear(s, 0, s->n_entries, true);
802
803 mutex_unlock(&stats->mutex);
804
805 return 1;
806}
807
808/*
809 * This is like jiffies_to_msec, but works for 64-bit values.
810 */
811static unsigned long long dm_jiffies_to_msec64(struct dm_stat *s, unsigned long long j)
812{
813 unsigned long long result;
814 unsigned mult;
815
816 if (s->stat_flags & STAT_PRECISE_TIMESTAMPS)
817 return j;
818
819 result = 0;
820 if (j)
821 result = jiffies_to_msecs(j & 0x3fffff);
822 if (j >= 1 << 22) {
823 mult = jiffies_to_msecs(1 << 22);
824 result += (unsigned long long)mult * (unsigned long long)jiffies_to_msecs((j >> 22) & 0x3fffff);
825 }
826 if (j >= 1ULL << 44)
827 result += (unsigned long long)mult * (unsigned long long)mult * (unsigned long long)jiffies_to_msecs(j >> 44);
828
829 return result;
830}
831
832static int dm_stats_print(struct dm_stats *stats, int id,
833 size_t idx_start, size_t idx_len,
834 bool clear, char *result, unsigned maxlen)
835{
836 unsigned sz = 0;
837 struct dm_stat *s;
838 size_t x;
839 sector_t start, end, step;
840 size_t idx_end;
841 struct dm_stat_shared *shared;
842
843 /*
844 * Output format:
845 * <start_sector>+<length> counters
846 */
847
848 mutex_lock(&stats->mutex);
849
850 s = __dm_stats_find(stats, id);
851 if (!s) {
852 mutex_unlock(&stats->mutex);
853 return -ENOENT;
854 }
855
856 idx_end = idx_start + idx_len;
857 if (idx_end < idx_start ||
858 idx_end > s->n_entries)
859 idx_end = s->n_entries;
860
861 if (idx_start > idx_end)
862 idx_start = idx_end;
863
864 step = s->step;
865 start = s->start + (step * idx_start);
866
867 for (x = idx_start; x < idx_end; x++, start = end) {
868 shared = &s->stat_shared[x];
869 end = start + step;
870 if (unlikely(end > s->end))
871 end = s->end;
872
873 __dm_stat_init_temporary_percpu_totals(shared, s, x);
874
875 DMEMIT("%llu+%llu %llu %llu %llu %llu %llu %llu %llu %llu %d %llu %llu %llu %llu",
876 (unsigned long long)start,
877 (unsigned long long)step,
878 shared->tmp.ios[READ],
879 shared->tmp.merges[READ],
880 shared->tmp.sectors[READ],
881 dm_jiffies_to_msec64(s, shared->tmp.ticks[READ]),
882 shared->tmp.ios[WRITE],
883 shared->tmp.merges[WRITE],
884 shared->tmp.sectors[WRITE],
885 dm_jiffies_to_msec64(s, shared->tmp.ticks[WRITE]),
886 dm_stat_in_flight(shared),
887 dm_jiffies_to_msec64(s, shared->tmp.io_ticks_total),
888 dm_jiffies_to_msec64(s, shared->tmp.time_in_queue),
889 dm_jiffies_to_msec64(s, shared->tmp.io_ticks[READ]),
890 dm_jiffies_to_msec64(s, shared->tmp.io_ticks[WRITE]));
891 if (s->n_histogram_entries) {
892 unsigned i;
893 for (i = 0; i < s->n_histogram_entries + 1; i++) {
894 DMEMIT("%s%llu", !i ? " " : ":", shared->tmp.histogram[i]);
895 }
896 }
897 DMEMIT("\n");
898
899 if (unlikely(sz + 1 >= maxlen))
900 goto buffer_overflow;
901
902 cond_resched();
903 }
904
905 if (clear)
906 __dm_stat_clear(s, idx_start, idx_end, false);
907
908buffer_overflow:
909 mutex_unlock(&stats->mutex);
910
911 return 1;
912}
913
914static int dm_stats_set_aux(struct dm_stats *stats, int id, const char *aux_data)
915{
916 struct dm_stat *s;
917 const char *new_aux_data;
918
919 mutex_lock(&stats->mutex);
920
921 s = __dm_stats_find(stats, id);
922 if (!s) {
923 mutex_unlock(&stats->mutex);
924 return -ENOENT;
925 }
926
927 new_aux_data = kstrdup(aux_data, GFP_KERNEL);
928 if (!new_aux_data) {
929 mutex_unlock(&stats->mutex);
930 return -ENOMEM;
931 }
932
933 kfree(s->aux_data);
934 s->aux_data = new_aux_data;
935
936 mutex_unlock(&stats->mutex);
937
938 return 0;
939}
940
941static int parse_histogram(const char *h, unsigned *n_histogram_entries,
942 unsigned long long **histogram_boundaries)
943{
944 const char *q;
945 unsigned n;
946 unsigned long long last;
947
948 *n_histogram_entries = 1;
949 for (q = h; *q; q++)
950 if (*q == ',')
951 (*n_histogram_entries)++;
952
953 *histogram_boundaries = kmalloc_array(*n_histogram_entries,
954 sizeof(unsigned long long),
955 GFP_KERNEL);
956 if (!*histogram_boundaries)
957 return -ENOMEM;
958
959 n = 0;
960 last = 0;
961 while (1) {
962 unsigned long long hi;
963 int s;
964 char ch;
965 s = sscanf(h, "%llu%c", &hi, &ch);
966 if (!s || (s == 2 && ch != ','))
967 return -EINVAL;
968 if (hi <= last)
969 return -EINVAL;
970 last = hi;
971 (*histogram_boundaries)[n] = hi;
972 if (s == 1)
973 return 0;
974 h = strchr(h, ',') + 1;
975 n++;
976 }
977}
978
979static int message_stats_create(struct mapped_device *md,
980 unsigned argc, char **argv,
981 char *result, unsigned maxlen)
982{
983 int r;
984 int id;
985 char dummy;
986 unsigned long long start, end, len, step;
987 unsigned divisor;
988 const char *program_id, *aux_data;
989 unsigned stat_flags = 0;
990
991 unsigned n_histogram_entries = 0;
992 unsigned long long *histogram_boundaries = NULL;
993
994 struct dm_arg_set as, as_backup;
995 const char *a;
996 unsigned feature_args;
997
998 /*
999 * Input format:
1000 * <range> <step> [<extra_parameters> <parameters>] [<program_id> [<aux_data>]]
1001 */
1002
1003 if (argc < 3)
1004 goto ret_einval;
1005
1006 as.argc = argc;
1007 as.argv = argv;
1008 dm_consume_args(&as, 1);
1009
1010 a = dm_shift_arg(&as);
1011 if (!strcmp(a, "-")) {
1012 start = 0;
1013 len = dm_get_size(md);
1014 if (!len)
1015 len = 1;
1016 } else if (sscanf(a, "%llu+%llu%c", &start, &len, &dummy) != 2 ||
1017 start != (sector_t)start || len != (sector_t)len)
1018 goto ret_einval;
1019
1020 end = start + len;
1021 if (start >= end)
1022 goto ret_einval;
1023
1024 a = dm_shift_arg(&as);
1025 if (sscanf(a, "/%u%c", &divisor, &dummy) == 1) {
1026 if (!divisor)
1027 return -EINVAL;
1028 step = end - start;
1029 if (do_div(step, divisor))
1030 step++;
1031 if (!step)
1032 step = 1;
1033 } else if (sscanf(a, "%llu%c", &step, &dummy) != 1 ||
1034 step != (sector_t)step || !step)
1035 goto ret_einval;
1036
1037 as_backup = as;
1038 a = dm_shift_arg(&as);
1039 if (a && sscanf(a, "%u%c", &feature_args, &dummy) == 1) {
1040 while (feature_args--) {
1041 a = dm_shift_arg(&as);
1042 if (!a)
1043 goto ret_einval;
1044 if (!strcasecmp(a, "precise_timestamps"))
1045 stat_flags |= STAT_PRECISE_TIMESTAMPS;
1046 else if (!strncasecmp(a, "histogram:", 10)) {
1047 if (n_histogram_entries)
1048 goto ret_einval;
1049 if ((r = parse_histogram(a + 10, &n_histogram_entries, &histogram_boundaries)))
1050 goto ret;
1051 } else
1052 goto ret_einval;
1053 }
1054 } else {
1055 as = as_backup;
1056 }
1057
1058 program_id = "-";
1059 aux_data = "-";
1060
1061 a = dm_shift_arg(&as);
1062 if (a)
1063 program_id = a;
1064
1065 a = dm_shift_arg(&as);
1066 if (a)
1067 aux_data = a;
1068
1069 if (as.argc)
1070 goto ret_einval;
1071
1072 /*
1073 * If a buffer overflow happens after we created the region,
1074 * it's too late (the userspace would retry with a larger
1075 * buffer, but the region id that caused the overflow is already
1076 * leaked). So we must detect buffer overflow in advance.
1077 */
1078 snprintf(result, maxlen, "%d", INT_MAX);
1079 if (dm_message_test_buffer_overflow(result, maxlen)) {
1080 r = 1;
1081 goto ret;
1082 }
1083
1084 id = dm_stats_create(dm_get_stats(md), start, end, step, stat_flags,
1085 n_histogram_entries, histogram_boundaries, program_id, aux_data,
1086 dm_internal_suspend_fast, dm_internal_resume_fast, md);
1087 if (id < 0) {
1088 r = id;
1089 goto ret;
1090 }
1091
1092 snprintf(result, maxlen, "%d", id);
1093
1094 r = 1;
1095 goto ret;
1096
1097ret_einval:
1098 r = -EINVAL;
1099ret:
1100 kfree(histogram_boundaries);
1101 return r;
1102}
1103
1104static int message_stats_delete(struct mapped_device *md,
1105 unsigned argc, char **argv)
1106{
1107 int id;
1108 char dummy;
1109
1110 if (argc != 2)
1111 return -EINVAL;
1112
1113 if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
1114 return -EINVAL;
1115
1116 return dm_stats_delete(dm_get_stats(md), id);
1117}
1118
1119static int message_stats_clear(struct mapped_device *md,
1120 unsigned argc, char **argv)
1121{
1122 int id;
1123 char dummy;
1124
1125 if (argc != 2)
1126 return -EINVAL;
1127
1128 if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
1129 return -EINVAL;
1130
1131 return dm_stats_clear(dm_get_stats(md), id);
1132}
1133
1134static int message_stats_list(struct mapped_device *md,
1135 unsigned argc, char **argv,
1136 char *result, unsigned maxlen)
1137{
1138 int r;
1139 const char *program = NULL;
1140
1141 if (argc < 1 || argc > 2)
1142 return -EINVAL;
1143
1144 if (argc > 1) {
1145 program = kstrdup(argv[1], GFP_KERNEL);
1146 if (!program)
1147 return -ENOMEM;
1148 }
1149
1150 r = dm_stats_list(dm_get_stats(md), program, result, maxlen);
1151
1152 kfree(program);
1153
1154 return r;
1155}
1156
1157static int message_stats_print(struct mapped_device *md,
1158 unsigned argc, char **argv, bool clear,
1159 char *result, unsigned maxlen)
1160{
1161 int id;
1162 char dummy;
1163 unsigned long idx_start = 0, idx_len = ULONG_MAX;
1164
1165 if (argc != 2 && argc != 4)
1166 return -EINVAL;
1167
1168 if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
1169 return -EINVAL;
1170
1171 if (argc > 3) {
1172 if (strcmp(argv[2], "-") &&
1173 sscanf(argv[2], "%lu%c", &idx_start, &dummy) != 1)
1174 return -EINVAL;
1175 if (strcmp(argv[3], "-") &&
1176 sscanf(argv[3], "%lu%c", &idx_len, &dummy) != 1)
1177 return -EINVAL;
1178 }
1179
1180 return dm_stats_print(dm_get_stats(md), id, idx_start, idx_len, clear,
1181 result, maxlen);
1182}
1183
1184static int message_stats_set_aux(struct mapped_device *md,
1185 unsigned argc, char **argv)
1186{
1187 int id;
1188 char dummy;
1189
1190 if (argc != 3)
1191 return -EINVAL;
1192
1193 if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
1194 return -EINVAL;
1195
1196 return dm_stats_set_aux(dm_get_stats(md), id, argv[2]);
1197}
1198
1199int dm_stats_message(struct mapped_device *md, unsigned argc, char **argv,
1200 char *result, unsigned maxlen)
1201{
1202 int r;
1203
1204 /* All messages here must start with '@' */
1205 if (!strcasecmp(argv[0], "@stats_create"))
1206 r = message_stats_create(md, argc, argv, result, maxlen);
1207 else if (!strcasecmp(argv[0], "@stats_delete"))
1208 r = message_stats_delete(md, argc, argv);
1209 else if (!strcasecmp(argv[0], "@stats_clear"))
1210 r = message_stats_clear(md, argc, argv);
1211 else if (!strcasecmp(argv[0], "@stats_list"))
1212 r = message_stats_list(md, argc, argv, result, maxlen);
1213 else if (!strcasecmp(argv[0], "@stats_print"))
1214 r = message_stats_print(md, argc, argv, false, result, maxlen);
1215 else if (!strcasecmp(argv[0], "@stats_print_clear"))
1216 r = message_stats_print(md, argc, argv, true, result, maxlen);
1217 else if (!strcasecmp(argv[0], "@stats_set_aux"))
1218 r = message_stats_set_aux(md, argc, argv);
1219 else
1220 return 2; /* this wasn't a stats message */
1221
1222 if (r == -EINVAL)
1223 DMCRIT("Invalid parameters for message %s", argv[0]);
1224
1225 return r;
1226}
1227
1228int __init dm_statistics_init(void)
1229{
1230 shared_memory_amount = 0;
1231 dm_stat_need_rcu_barrier = 0;
1232 return 0;
1233}
1234
1235void dm_statistics_exit(void)
1236{
1237 if (dm_stat_need_rcu_barrier)
1238 rcu_barrier();
1239 if (WARN_ON(shared_memory_amount))
1240 DMCRIT("shared_memory_amount leaked: %lu", shared_memory_amount);
1241}
1242
1243module_param_named(stats_current_allocated_bytes, shared_memory_amount, ulong, S_IRUGO);
1244MODULE_PARM_DESC(stats_current_allocated_bytes, "Memory currently used by statistics");
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
18static 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 */
24struct 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
34struct dm_stat_shared {
35 atomic_t in_flight[2];
36 unsigned long stamp;
37 struct dm_stat_percpu tmp;
38};
39
40struct 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
56struct 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
69static DEFINE_SPINLOCK(shared_memory_lock);
70
71static unsigned long shared_memory_amount;
72
73static 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
89static 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
102static 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
118static 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
135static 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
156static 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
169static 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
181static 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
187void 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
202void 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
229static 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
336out_unlock_resume:
337 mutex_unlock(&stats->mutex);
338 resume_callback(md);
339out:
340 dm_stat_free(&s->rcu_head);
341 return r;
342}
343
344static 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
358static 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)) {
381do_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
391static 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
420static 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
445static 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
495static 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
533void 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 = __this_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
569static 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
598static 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
627static 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 */
649static 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
666static 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
733buffer_overflow:
734 mutex_unlock(&stats->mutex);
735
736 return 1;
737}
738
739static 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
766static 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, dm_internal_resume, md);
828 if (id < 0)
829 return id;
830
831 snprintf(result, maxlen, "%d", id);
832
833 return 1;
834}
835
836static 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
851static 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
866static 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
889static 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
916static 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
931int 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
965int __init dm_statistics_init(void)
966{
967 shared_memory_amount = 0;
968 dm_stat_need_rcu_barrier = 0;
969 return 0;
970}
971
972void 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
980module_param_named(stats_current_allocated_bytes, shared_memory_amount, ulong, S_IRUGO);
981MODULE_PARM_DESC(stats_current_allocated_bytes, "Memory currently used by statistics");