drivers/md/dm-stats.c

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