drivers/md/dm-stats.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   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 int stat_flags;
  46         size_t n_entries;
  47         sector_t start;
  48         sector_t end;
  49         sector_t step;
  50         unsigned int 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
  64 struct dm_stats_last_position {
  65         sector_t last_sector;
  66         unsigned int 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->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
 207 void 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
 236 static 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
 252 static int dm_stats_create(struct dm_stats *stats, sector_t start, sector_t end,
 253                            sector_t step, unsigned int stat_flags,
 254                            unsigned int 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
 340                 hi = dm_kvzalloc(s->histogram_alloc_size, NUMA_NO_NODE);
 341                 if (!hi) {
 342                         r = -ENOMEM;
 343                         goto out;
 344                 }
 345                 for (ni = 0; ni < n_entries; ni++) {
 346                         s->stat_shared[ni].tmp.histogram = hi;
 347                         hi += s->n_histogram_entries + 1;
 348                         cond_resched();
 349                 }
 350         }
 351
 352         for_each_possible_cpu(cpu) {
 353                 p = dm_kvzalloc(percpu_alloc_size, cpu_to_node(cpu));
 354                 if (!p) {
 355                         r = -ENOMEM;
 356                         goto out;
 357                 }
 358                 s->stat_percpu[cpu] = p;
 359                 if (s->n_histogram_entries) {
 360                         unsigned long long *hi;
 361
 362                         hi = dm_kvzalloc(s->histogram_alloc_size, cpu_to_node(cpu));
 363                         if (!hi) {
 364                                 r = -ENOMEM;
 365                                 goto out;
 366                         }
 367                         for (ni = 0; ni < n_entries; ni++) {
 368                                 p[ni].histogram = hi;
 369                                 hi += s->n_histogram_entries + 1;
 370                                 cond_resched();
 371                         }
 372                 }
 373         }
 374
 375         /*
 376          * Suspend/resume to make sure there is no i/o in flight,
 377          * so that newly created statistics will be exact.
 378          *
 379          * (note: we couldn't suspend earlier because we must not
 380          * allocate memory while suspended)
 381          */
 382         suspend_callback(md);
 383
 384         mutex_lock(&stats->mutex);
 385         s->id = 0;
 386         list_for_each(l, &stats->list) {
 387                 tmp_s = container_of(l, struct dm_stat, list_entry);
 388                 if (WARN_ON(tmp_s->id < s->id)) {
 389                         r = -EINVAL;
 390                         goto out_unlock_resume;
 391                 }
 392                 if (tmp_s->id > s->id)
 393                         break;
 394                 if (unlikely(s->id == INT_MAX)) {
 395                         r = -ENFILE;
 396                         goto out_unlock_resume;
 397                 }
 398                 s->id++;
 399         }
 400         ret_id = s->id;
 401         list_add_tail_rcu(&s->list_entry, l);
 402
 403         dm_stats_recalc_precise_timestamps(stats);
 404
 405         if (!static_key_enabled(&stats_enabled.key))
 406                 static_branch_enable(&stats_enabled);
 407
 408         mutex_unlock(&stats->mutex);
 409
 410         resume_callback(md);
 411
 412         return ret_id;
 413
 414 out_unlock_resume:
 415         mutex_unlock(&stats->mutex);
 416         resume_callback(md);
 417 out:
 418         dm_stat_free(&s->rcu_head);
 419         return r;
 420 }
 421
 422 static struct dm_stat *__dm_stats_find(struct dm_stats *stats, int id)
 423 {
 424         struct dm_stat *s;
 425
 426         list_for_each_entry(s, &stats->list, list_entry) {
 427                 if (s->id > id)
 428                         break;
 429                 if (s->id == id)
 430                         return s;
 431         }
 432
 433         return NULL;
 434 }
 435
 436 static int dm_stats_delete(struct dm_stats *stats, int id)
 437 {
 438         struct dm_stat *s;
 439         int cpu;
 440
 441         mutex_lock(&stats->mutex);
 442
 443         s = __dm_stats_find(stats, id);
 444         if (!s) {
 445                 mutex_unlock(&stats->mutex);
 446                 return -ENOENT;
 447         }
 448
 449         list_del_rcu(&s->list_entry);
 450
 451         dm_stats_recalc_precise_timestamps(stats);
 452
 453         mutex_unlock(&stats->mutex);
 454
 455         /*
 456          * vfree can't be called from RCU callback
 457          */
 458         for_each_possible_cpu(cpu)
 459                 if (is_vmalloc_addr(s->stat_percpu) ||
 460                     is_vmalloc_addr(s->stat_percpu[cpu][0].histogram))
 461                         goto do_sync_free;
 462         if (is_vmalloc_addr(s) ||
 463             is_vmalloc_addr(s->stat_shared[0].tmp.histogram)) {
 464 do_sync_free:
 465                 synchronize_rcu_expedited();
 466                 dm_stat_free(&s->rcu_head);
 467         } else {
 468                 WRITE_ONCE(dm_stat_need_rcu_barrier, 1);
 469                 call_rcu(&s->rcu_head, dm_stat_free);
 470         }
 471         return 0;
 472 }
 473
 474 static int dm_stats_list(struct dm_stats *stats, const char *program,
 475                          char *result, unsigned int maxlen)
 476 {
 477         struct dm_stat *s;
 478         sector_t len;
 479         unsigned int sz = 0;
 480
 481         /*
 482          * Output format:
 483          *   <region_id>: <start_sector>+<length> <step> <program_id> <aux_data>
 484          */
 485
 486         mutex_lock(&stats->mutex);
 487         list_for_each_entry(s, &stats->list, list_entry) {
 488                 if (!program || !strcmp(program, s->program_id)) {
 489                         len = s->end - s->start;
 490                         DMEMIT("%d: %llu+%llu %llu %s %s", s->id,
 491                                 (unsigned long long)s->start,
 492                                 (unsigned long long)len,
 493                                 (unsigned long long)s->step,
 494                                 s->program_id,
 495                                 s->aux_data);
 496                         if (s->stat_flags & STAT_PRECISE_TIMESTAMPS)
 497                                 DMEMIT(" precise_timestamps");
 498                         if (s->n_histogram_entries) {
 499                                 unsigned int i;
 500
 501                                 DMEMIT(" histogram:");
 502                                 for (i = 0; i < s->n_histogram_entries; i++) {
 503                                         if (i)
 504                                                 DMEMIT(",");
 505                                         DMEMIT("%llu", s->histogram_boundaries[i]);
 506                                 }
 507                         }
 508                         DMEMIT("\n");
 509                 }
 510                 cond_resched();
 511         }
 512         mutex_unlock(&stats->mutex);
 513
 514         return 1;
 515 }
 516
 517 static void dm_stat_round(struct dm_stat *s, struct dm_stat_shared *shared,
 518                           struct dm_stat_percpu *p)
 519 {
 520         /*
 521          * This is racy, but so is part_round_stats_single.
 522          */
 523         unsigned long long now, difference;
 524         unsigned int in_flight_read, in_flight_write;
 525
 526         if (likely(!(s->stat_flags & STAT_PRECISE_TIMESTAMPS)))
 527                 now = jiffies;
 528         else
 529                 now = ktime_to_ns(ktime_get());
 530
 531         difference = now - shared->stamp;
 532         if (!difference)
 533                 return;
 534
 535         in_flight_read = (unsigned int)atomic_read(&shared->in_flight[READ]);
 536         in_flight_write = (unsigned int)atomic_read(&shared->in_flight[WRITE]);
 537         if (in_flight_read)
 538                 p->io_ticks[READ] += difference;
 539         if (in_flight_write)
 540                 p->io_ticks[WRITE] += difference;
 541         if (in_flight_read + in_flight_write) {
 542                 p->io_ticks_total += difference;
 543                 p->time_in_queue += (in_flight_read + in_flight_write) * difference;
 544         }
 545         shared->stamp = now;
 546 }
 547
 548 static void dm_stat_for_entry(struct dm_stat *s, size_t entry,
 549                               int idx, sector_t len,
 550                               struct dm_stats_aux *stats_aux, bool end,
 551                               unsigned long duration_jiffies)
 552 {
 553         struct dm_stat_shared *shared = &s->stat_shared[entry];
 554         struct dm_stat_percpu *p;
 555
 556         /*
 557          * For strict correctness we should use local_irq_save/restore
 558          * instead of preempt_disable/enable.
 559          *
 560          * preempt_disable/enable is racy if the driver finishes bios
 561          * from non-interrupt context as well as from interrupt context
 562          * or from more different interrupts.
 563          *
 564          * On 64-bit architectures the race only results in not counting some
 565          * events, so it is acceptable.  On 32-bit architectures the race could
 566          * cause the counter going off by 2^32, so we need to do proper locking
 567          * there.
 568          *
 569          * part_stat_lock()/part_stat_unlock() have this race too.
 570          */
 571 #if BITS_PER_LONG == 32
 572         unsigned long flags;
 573
 574         local_irq_save(flags);
 575 #else
 576         preempt_disable();
 577 #endif
 578         p = &s->stat_percpu[smp_processor_id()][entry];
 579
 580         if (!end) {
 581                 dm_stat_round(s, shared, p);
 582                 atomic_inc(&shared->in_flight[idx]);
 583         } else {
 584                 unsigned long long duration;
 585
 586                 dm_stat_round(s, shared, p);
 587                 atomic_dec(&shared->in_flight[idx]);
 588                 p->sectors[idx] += len;
 589                 p->ios[idx] += 1;
 590                 p->merges[idx] += stats_aux->merged;
 591                 if (!(s->stat_flags & STAT_PRECISE_TIMESTAMPS)) {
 592                         p->ticks[idx] += duration_jiffies;
 593                         duration = jiffies_to_msecs(duration_jiffies);
 594                 } else {
 595                         p->ticks[idx] += stats_aux->duration_ns;
 596                         duration = stats_aux->duration_ns;
 597                 }
 598                 if (s->n_histogram_entries) {
 599                         unsigned int lo = 0, hi = s->n_histogram_entries + 1;
 600
 601                         while (lo + 1 < hi) {
 602                                 unsigned int mid = (lo + hi) / 2;
 603
 604                                 if (s->histogram_boundaries[mid - 1] > duration)
 605                                         hi = mid;
 606                                 else
 607                                         lo = mid;
 608                         }
 609                         p->histogram[lo]++;
 610                 }
 611         }
 612
 613 #if BITS_PER_LONG == 32
 614         local_irq_restore(flags);
 615 #else
 616         preempt_enable();
 617 #endif
 618 }
 619
 620 static void __dm_stat_bio(struct dm_stat *s, int bi_rw,
 621                           sector_t bi_sector, sector_t end_sector,
 622                           bool end, unsigned long duration_jiffies,
 623                           struct dm_stats_aux *stats_aux)
 624 {
 625         sector_t rel_sector, offset, todo, fragment_len;
 626         size_t entry;
 627
 628         if (end_sector <= s->start || bi_sector >= s->end)
 629                 return;
 630         if (unlikely(bi_sector < s->start)) {
 631                 rel_sector = 0;
 632                 todo = end_sector - s->start;
 633         } else {
 634                 rel_sector = bi_sector - s->start;
 635                 todo = end_sector - bi_sector;
 636         }
 637         if (unlikely(end_sector > s->end))
 638                 todo -= (end_sector - s->end);
 639
 640         offset = dm_sector_div64(rel_sector, s->step);
 641         entry = rel_sector;
 642         do {
 643                 if (WARN_ON_ONCE(entry >= s->n_entries)) {
 644                         DMCRIT("Invalid area access in region id %d", s->id);
 645                         return;
 646                 }
 647                 fragment_len = todo;
 648                 if (fragment_len > s->step - offset)
 649                         fragment_len = s->step - offset;
 650                 dm_stat_for_entry(s, entry, bi_rw, fragment_len,
 651                                   stats_aux, end, duration_jiffies);
 652                 todo -= fragment_len;
 653                 entry++;
 654                 offset = 0;
 655         } while (unlikely(todo != 0));
 656 }
 657
 658 void dm_stats_account_io(struct dm_stats *stats, unsigned long bi_rw,
 659                          sector_t bi_sector, unsigned int bi_sectors, bool end,
 660                          unsigned long start_time,
 661                          struct dm_stats_aux *stats_aux)
 662 {
 663         struct dm_stat *s;
 664         sector_t end_sector;
 665         struct dm_stats_last_position *last;
 666         bool got_precise_time;
 667         unsigned long duration_jiffies = 0;
 668
 669         if (unlikely(!bi_sectors))
 670                 return;
 671
 672         end_sector = bi_sector + bi_sectors;
 673
 674         if (!end) {
 675                 /*
 676                  * A race condition can at worst result in the merged flag being
 677                  * misrepresented, so we don't have to disable preemption here.
 678                  */
 679                 last = raw_cpu_ptr(stats->last);
 680                 stats_aux->merged =
 681                         (bi_sector == (READ_ONCE(last->last_sector) &&
 682                                        ((bi_rw == WRITE) ==
 683                                         (READ_ONCE(last->last_rw) == WRITE))
 684                                        ));
 685                 WRITE_ONCE(last->last_sector, end_sector);
 686                 WRITE_ONCE(last->last_rw, bi_rw);
 687         } else
 688                 duration_jiffies = jiffies - start_time;
 689
 690         rcu_read_lock();
 691
 692         got_precise_time = false;
 693         list_for_each_entry_rcu(s, &stats->list, list_entry) {
 694                 if (s->stat_flags & STAT_PRECISE_TIMESTAMPS && !got_precise_time) {
 695                         /* start (!end) duration_ns is set by DM core's alloc_io() */
 696                         if (end)
 697                                 stats_aux->duration_ns = ktime_to_ns(ktime_get()) - stats_aux->duration_ns;
 698                         got_precise_time = true;
 699                 }
 700                 __dm_stat_bio(s, bi_rw, bi_sector, end_sector, end, duration_jiffies, stats_aux);
 701         }
 702
 703         rcu_read_unlock();
 704 }
 705
 706 static void __dm_stat_init_temporary_percpu_totals(struct dm_stat_shared *shared,
 707                                                    struct dm_stat *s, size_t x)
 708 {
 709         int cpu;
 710         struct dm_stat_percpu *p;
 711
 712         local_irq_disable();
 713         p = &s->stat_percpu[smp_processor_id()][x];
 714         dm_stat_round(s, shared, p);
 715         local_irq_enable();
 716
 717         shared->tmp.sectors[READ] = 0;
 718         shared->tmp.sectors[WRITE] = 0;
 719         shared->tmp.ios[READ] = 0;
 720         shared->tmp.ios[WRITE] = 0;
 721         shared->tmp.merges[READ] = 0;
 722         shared->tmp.merges[WRITE] = 0;
 723         shared->tmp.ticks[READ] = 0;
 724         shared->tmp.ticks[WRITE] = 0;
 725         shared->tmp.io_ticks[READ] = 0;
 726         shared->tmp.io_ticks[WRITE] = 0;
 727         shared->tmp.io_ticks_total = 0;
 728         shared->tmp.time_in_queue = 0;
 729
 730         if (s->n_histogram_entries)
 731                 memset(shared->tmp.histogram, 0, (s->n_histogram_entries + 1) * sizeof(unsigned long long));
 732
 733         for_each_possible_cpu(cpu) {
 734                 p = &s->stat_percpu[cpu][x];
 735                 shared->tmp.sectors[READ] += READ_ONCE(p->sectors[READ]);
 736                 shared->tmp.sectors[WRITE] += READ_ONCE(p->sectors[WRITE]);
 737                 shared->tmp.ios[READ] += READ_ONCE(p->ios[READ]);
 738                 shared->tmp.ios[WRITE] += READ_ONCE(p->ios[WRITE]);
 739                 shared->tmp.merges[READ] += READ_ONCE(p->merges[READ]);
 740                 shared->tmp.merges[WRITE] += READ_ONCE(p->merges[WRITE]);
 741                 shared->tmp.ticks[READ] += READ_ONCE(p->ticks[READ]);
 742                 shared->tmp.ticks[WRITE] += READ_ONCE(p->ticks[WRITE]);
 743                 shared->tmp.io_ticks[READ] += READ_ONCE(p->io_ticks[READ]);
 744                 shared->tmp.io_ticks[WRITE] += READ_ONCE(p->io_ticks[WRITE]);
 745                 shared->tmp.io_ticks_total += READ_ONCE(p->io_ticks_total);
 746                 shared->tmp.time_in_queue += READ_ONCE(p->time_in_queue);
 747                 if (s->n_histogram_entries) {
 748                         unsigned int i;
 749
 750                         for (i = 0; i < s->n_histogram_entries + 1; i++)
 751                                 shared->tmp.histogram[i] += READ_ONCE(p->histogram[i]);
 752                 }
 753         }
 754 }
 755
 756 static void __dm_stat_clear(struct dm_stat *s, size_t idx_start, size_t idx_end,
 757                             bool init_tmp_percpu_totals)
 758 {
 759         size_t x;
 760         struct dm_stat_shared *shared;
 761         struct dm_stat_percpu *p;
 762
 763         for (x = idx_start; x < idx_end; x++) {
 764                 shared = &s->stat_shared[x];
 765                 if (init_tmp_percpu_totals)
 766                         __dm_stat_init_temporary_percpu_totals(shared, s, x);
 767                 local_irq_disable();
 768                 p = &s->stat_percpu[smp_processor_id()][x];
 769                 p->sectors[READ] -= shared->tmp.sectors[READ];
 770                 p->sectors[WRITE] -= shared->tmp.sectors[WRITE];
 771                 p->ios[READ] -= shared->tmp.ios[READ];
 772                 p->ios[WRITE] -= shared->tmp.ios[WRITE];
 773                 p->merges[READ] -= shared->tmp.merges[READ];
 774                 p->merges[WRITE] -= shared->tmp.merges[WRITE];
 775                 p->ticks[READ] -= shared->tmp.ticks[READ];
 776                 p->ticks[WRITE] -= shared->tmp.ticks[WRITE];
 777                 p->io_ticks[READ] -= shared->tmp.io_ticks[READ];
 778                 p->io_ticks[WRITE] -= shared->tmp.io_ticks[WRITE];
 779                 p->io_ticks_total -= shared->tmp.io_ticks_total;
 780                 p->time_in_queue -= shared->tmp.time_in_queue;
 781                 local_irq_enable();
 782                 if (s->n_histogram_entries) {
 783                         unsigned int i;
 784
 785                         for (i = 0; i < s->n_histogram_entries + 1; i++) {
 786                                 local_irq_disable();
 787                                 p = &s->stat_percpu[smp_processor_id()][x];
 788                                 p->histogram[i] -= shared->tmp.histogram[i];
 789                                 local_irq_enable();
 790                         }
 791                 }
 792                 cond_resched();
 793         }
 794 }
 795
 796 static int dm_stats_clear(struct dm_stats *stats, int id)
 797 {
 798         struct dm_stat *s;
 799
 800         mutex_lock(&stats->mutex);
 801
 802         s = __dm_stats_find(stats, id);
 803         if (!s) {
 804                 mutex_unlock(&stats->mutex);
 805                 return -ENOENT;
 806         }
 807
 808         __dm_stat_clear(s, 0, s->n_entries, true);
 809
 810         mutex_unlock(&stats->mutex);
 811
 812         return 1;
 813 }
 814
 815 /*
 816  * This is like jiffies_to_msec, but works for 64-bit values.
 817  */
 818 static unsigned long long dm_jiffies_to_msec64(struct dm_stat *s, unsigned long long j)
 819 {
 820         unsigned long long result;
 821         unsigned int mult;
 822
 823         if (s->stat_flags & STAT_PRECISE_TIMESTAMPS)
 824                 return j;
 825
 826         result = 0;
 827         if (j)
 828                 result = jiffies_to_msecs(j & 0x3fffff);
 829         if (j >= 1 << 22) {
 830                 mult = jiffies_to_msecs(1 << 22);
 831                 result += (unsigned long long)mult * (unsigned long long)jiffies_to_msecs((j >> 22) & 0x3fffff);
 832         }
 833         if (j >= 1ULL << 44)
 834                 result += (unsigned long long)mult * (unsigned long long)mult * (unsigned long long)jiffies_to_msecs(j >> 44);
 835
 836         return result;
 837 }
 838
 839 static int dm_stats_print(struct dm_stats *stats, int id,
 840                           size_t idx_start, size_t idx_len,
 841                           bool clear, char *result, unsigned int maxlen)
 842 {
 843         unsigned int sz = 0;
 844         struct dm_stat *s;
 845         size_t x;
 846         sector_t start, end, step;
 847         size_t idx_end;
 848         struct dm_stat_shared *shared;
 849
 850         /*
 851          * Output format:
 852          *   <start_sector>+<length> counters
 853          */
 854
 855         mutex_lock(&stats->mutex);
 856
 857         s = __dm_stats_find(stats, id);
 858         if (!s) {
 859                 mutex_unlock(&stats->mutex);
 860                 return -ENOENT;
 861         }
 862
 863         idx_end = idx_start + idx_len;
 864         if (idx_end < idx_start ||
 865             idx_end > s->n_entries)
 866                 idx_end = s->n_entries;
 867
 868         if (idx_start > idx_end)
 869                 idx_start = idx_end;
 870
 871         step = s->step;
 872         start = s->start + (step * idx_start);
 873
 874         for (x = idx_start; x < idx_end; x++, start = end) {
 875                 shared = &s->stat_shared[x];
 876                 end = start + step;
 877                 if (unlikely(end > s->end))
 878                         end = s->end;
 879
 880                 __dm_stat_init_temporary_percpu_totals(shared, s, x);
 881
 882                 DMEMIT("%llu+%llu %llu %llu %llu %llu %llu %llu %llu %llu %d %llu %llu %llu %llu",
 883                        (unsigned long long)start,
 884                        (unsigned long long)step,
 885                        shared->tmp.ios[READ],
 886                        shared->tmp.merges[READ],
 887                        shared->tmp.sectors[READ],
 888                        dm_jiffies_to_msec64(s, shared->tmp.ticks[READ]),
 889                        shared->tmp.ios[WRITE],
 890                        shared->tmp.merges[WRITE],
 891                        shared->tmp.sectors[WRITE],
 892                        dm_jiffies_to_msec64(s, shared->tmp.ticks[WRITE]),
 893                        dm_stat_in_flight(shared),
 894                        dm_jiffies_to_msec64(s, shared->tmp.io_ticks_total),
 895                        dm_jiffies_to_msec64(s, shared->tmp.time_in_queue),
 896                        dm_jiffies_to_msec64(s, shared->tmp.io_ticks[READ]),
 897                        dm_jiffies_to_msec64(s, shared->tmp.io_ticks[WRITE]));
 898                 if (s->n_histogram_entries) {
 899                         unsigned int i;
 900
 901                         for (i = 0; i < s->n_histogram_entries + 1; i++)
 902                                 DMEMIT("%s%llu", !i ? " " : ":", shared->tmp.histogram[i]);
 903                 }
 904                 DMEMIT("\n");
 905
 906                 if (unlikely(sz + 1 >= maxlen))
 907                         goto buffer_overflow;
 908
 909                 cond_resched();
 910         }
 911
 912         if (clear)
 913                 __dm_stat_clear(s, idx_start, idx_end, false);
 914
 915 buffer_overflow:
 916         mutex_unlock(&stats->mutex);
 917
 918         return 1;
 919 }
 920
 921 static int dm_stats_set_aux(struct dm_stats *stats, int id, const char *aux_data)
 922 {
 923         struct dm_stat *s;
 924         const char *new_aux_data;
 925
 926         mutex_lock(&stats->mutex);
 927
 928         s = __dm_stats_find(stats, id);
 929         if (!s) {
 930                 mutex_unlock(&stats->mutex);
 931                 return -ENOENT;
 932         }
 933
 934         new_aux_data = kstrdup(aux_data, GFP_KERNEL);
 935         if (!new_aux_data) {
 936                 mutex_unlock(&stats->mutex);
 937                 return -ENOMEM;
 938         }
 939
 940         kfree(s->aux_data);
 941         s->aux_data = new_aux_data;
 942
 943         mutex_unlock(&stats->mutex);
 944
 945         return 0;
 946 }
 947
 948 static int parse_histogram(const char *h, unsigned int *n_histogram_entries,
 949                            unsigned long long **histogram_boundaries)
 950 {
 951         const char *q;
 952         unsigned int n;
 953         unsigned long long last;
 954
 955         *n_histogram_entries = 1;
 956         for (q = h; *q; q++)
 957                 if (*q == ',')
 958                         (*n_histogram_entries)++;
 959
 960         *histogram_boundaries = kmalloc_array(*n_histogram_entries,
 961                                               sizeof(unsigned long long),
 962                                               GFP_KERNEL);
 963         if (!*histogram_boundaries)
 964                 return -ENOMEM;
 965
 966         n = 0;
 967         last = 0;
 968         while (1) {
 969                 unsigned long long hi;
 970                 int s;
 971                 char ch;
 972
 973                 s = sscanf(h, "%llu%c", &hi, &ch);
 974                 if (!s || (s == 2 && ch != ','))
 975                         return -EINVAL;
 976                 if (hi <= last)
 977                         return -EINVAL;
 978                 last = hi;
 979                 (*histogram_boundaries)[n] = hi;
 980                 if (s == 1)
 981                         return 0;
 982                 h = strchr(h, ',') + 1;
 983                 n++;
 984         }
 985 }
 986
 987 static int message_stats_create(struct mapped_device *md,
 988                                 unsigned int argc, char **argv,
 989                                 char *result, unsigned int maxlen)
 990 {
 991         int r;
 992         int id;
 993         char dummy;
 994         unsigned long long start, end, len, step;
 995         unsigned int divisor;
 996         const char *program_id, *aux_data;
 997         unsigned int stat_flags = 0;
 998         unsigned int n_histogram_entries = 0;
 999         unsigned long long *histogram_boundaries = NULL;
1000         struct dm_arg_set as, as_backup;
1001         const char *a;
1002         unsigned int feature_args;
1003
1004         /*
1005          * Input format:
1006          *   <range> <step> [<extra_parameters> <parameters>] [<program_id> [<aux_data>]]
1007          */
1008
1009         if (argc < 3)
1010                 goto ret_einval;
1011
1012         as.argc = argc;
1013         as.argv = argv;
1014         dm_consume_args(&as, 1);
1015
1016         a = dm_shift_arg(&as);
1017         if (!strcmp(a, "-")) {
1018                 start = 0;
1019                 len = dm_get_size(md);
1020                 if (!len)
1021                         len = 1;
1022         } else if (sscanf(a, "%llu+%llu%c", &start, &len, &dummy) != 2 ||
1023                    start != (sector_t)start || len != (sector_t)len)
1024                 goto ret_einval;
1025
1026         end = start + len;
1027         if (start >= end)
1028                 goto ret_einval;
1029
1030         a = dm_shift_arg(&as);
1031         if (sscanf(a, "/%u%c", &divisor, &dummy) == 1) {
1032                 if (!divisor)
1033                         return -EINVAL;
1034                 step = end - start;
1035                 if (do_div(step, divisor))
1036                         step++;
1037                 if (!step)
1038                         step = 1;
1039         } else if (sscanf(a, "%llu%c", &step, &dummy) != 1 ||
1040                    step != (sector_t)step || !step)
1041                 goto ret_einval;
1042
1043         as_backup = as;
1044         a = dm_shift_arg(&as);
1045         if (a && sscanf(a, "%u%c", &feature_args, &dummy) == 1) {
1046                 while (feature_args--) {
1047                         a = dm_shift_arg(&as);
1048                         if (!a)
1049                                 goto ret_einval;
1050                         if (!strcasecmp(a, "precise_timestamps"))
1051                                 stat_flags |= STAT_PRECISE_TIMESTAMPS;
1052                         else if (!strncasecmp(a, "histogram:", 10)) {
1053                                 if (n_histogram_entries)
1054                                         goto ret_einval;
1055                                 r = parse_histogram(a + 10, &n_histogram_entries, &histogram_boundaries);
1056                                 if (r)
1057                                         goto ret;
1058                         } else
1059                                 goto ret_einval;
1060                 }
1061         } else {
1062                 as = as_backup;
1063         }
1064
1065         program_id = "-";
1066         aux_data = "-";
1067
1068         a = dm_shift_arg(&as);
1069         if (a)
1070                 program_id = a;
1071
1072         a = dm_shift_arg(&as);
1073         if (a)
1074                 aux_data = a;
1075
1076         if (as.argc)
1077                 goto ret_einval;
1078
1079         /*
1080          * If a buffer overflow happens after we created the region,
1081          * it's too late (the userspace would retry with a larger
1082          * buffer, but the region id that caused the overflow is already
1083          * leaked).  So we must detect buffer overflow in advance.
1084          */
1085         snprintf(result, maxlen, "%d", INT_MAX);
1086         if (dm_message_test_buffer_overflow(result, maxlen)) {
1087                 r = 1;
1088                 goto ret;
1089         }
1090
1091         id = dm_stats_create(dm_get_stats(md), start, end, step, stat_flags,
1092                              n_histogram_entries, histogram_boundaries, program_id, aux_data,
1093                              dm_internal_suspend_fast, dm_internal_resume_fast, md);
1094         if (id < 0) {
1095                 r = id;
1096                 goto ret;
1097         }
1098
1099         snprintf(result, maxlen, "%d", id);
1100
1101         r = 1;
1102         goto ret;
1103
1104 ret_einval:
1105         r = -EINVAL;
1106 ret:
1107         kfree(histogram_boundaries);
1108         return r;
1109 }
1110
1111 static int message_stats_delete(struct mapped_device *md,
1112                                 unsigned int argc, char **argv)
1113 {
1114         int id;
1115         char dummy;
1116
1117         if (argc != 2)
1118                 return -EINVAL;
1119
1120         if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
1121                 return -EINVAL;
1122
1123         return dm_stats_delete(dm_get_stats(md), id);
1124 }
1125
1126 static int message_stats_clear(struct mapped_device *md,
1127                                unsigned int argc, char **argv)
1128 {
1129         int id;
1130         char dummy;
1131
1132         if (argc != 2)
1133                 return -EINVAL;
1134
1135         if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
1136                 return -EINVAL;
1137
1138         return dm_stats_clear(dm_get_stats(md), id);
1139 }
1140
1141 static int message_stats_list(struct mapped_device *md,
1142                               unsigned int argc, char **argv,
1143                               char *result, unsigned int maxlen)
1144 {
1145         int r;
1146         const char *program = NULL;
1147
1148         if (argc < 1 || argc > 2)
1149                 return -EINVAL;
1150
1151         if (argc > 1) {
1152                 program = kstrdup(argv[1], GFP_KERNEL);
1153                 if (!program)
1154                         return -ENOMEM;
1155         }
1156
1157         r = dm_stats_list(dm_get_stats(md), program, result, maxlen);
1158
1159         kfree(program);
1160
1161         return r;
1162 }
1163
1164 static int message_stats_print(struct mapped_device *md,
1165                                unsigned int argc, char **argv, bool clear,
1166                                char *result, unsigned int maxlen)
1167 {
1168         int id;
1169         char dummy;
1170         unsigned long idx_start = 0, idx_len = ULONG_MAX;
1171
1172         if (argc != 2 && argc != 4)
1173                 return -EINVAL;
1174
1175         if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
1176                 return -EINVAL;
1177
1178         if (argc > 3) {
1179                 if (strcmp(argv[2], "-") &&
1180                     sscanf(argv[2], "%lu%c", &idx_start, &dummy) != 1)
1181                         return -EINVAL;
1182                 if (strcmp(argv[3], "-") &&
1183                     sscanf(argv[3], "%lu%c", &idx_len, &dummy) != 1)
1184                         return -EINVAL;
1185         }
1186
1187         return dm_stats_print(dm_get_stats(md), id, idx_start, idx_len, clear,
1188                               result, maxlen);
1189 }
1190
1191 static int message_stats_set_aux(struct mapped_device *md,
1192                                  unsigned int argc, char **argv)
1193 {
1194         int id;
1195         char dummy;
1196
1197         if (argc != 3)
1198                 return -EINVAL;
1199
1200         if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
1201                 return -EINVAL;
1202
1203         return dm_stats_set_aux(dm_get_stats(md), id, argv[2]);
1204 }
1205
1206 int dm_stats_message(struct mapped_device *md, unsigned int argc, char **argv,
1207                      char *result, unsigned int maxlen)
1208 {
1209         int r;
1210
1211         /* All messages here must start with '@' */
1212         if (!strcasecmp(argv[0], "@stats_create"))
1213                 r = message_stats_create(md, argc, argv, result, maxlen);
1214         else if (!strcasecmp(argv[0], "@stats_delete"))
1215                 r = message_stats_delete(md, argc, argv);
1216         else if (!strcasecmp(argv[0], "@stats_clear"))
1217                 r = message_stats_clear(md, argc, argv);
1218         else if (!strcasecmp(argv[0], "@stats_list"))
1219                 r = message_stats_list(md, argc, argv, result, maxlen);
1220         else if (!strcasecmp(argv[0], "@stats_print"))
1221                 r = message_stats_print(md, argc, argv, false, result, maxlen);
1222         else if (!strcasecmp(argv[0], "@stats_print_clear"))
1223                 r = message_stats_print(md, argc, argv, true, result, maxlen);
1224         else if (!strcasecmp(argv[0], "@stats_set_aux"))
1225                 r = message_stats_set_aux(md, argc, argv);
1226         else
1227                 return 2; /* this wasn't a stats message */
1228
1229         if (r == -EINVAL)
1230                 DMCRIT("Invalid parameters for message %s", argv[0]);
1231
1232         return r;
1233 }
1234
1235 int __init dm_statistics_init(void)
1236 {
1237         shared_memory_amount = 0;
1238         dm_stat_need_rcu_barrier = 0;
1239         return 0;
1240 }
1241
1242 void dm_statistics_exit(void)
1243 {
1244         if (dm_stat_need_rcu_barrier)
1245                 rcu_barrier();
1246         if (WARN_ON(shared_memory_amount))
1247                 DMCRIT("shared_memory_amount leaked: %lu", shared_memory_amount);
1248 }
1249
1250 module_param_named(stats_current_allocated_bytes, shared_memory_amount, ulong, 0444);
1251 MODULE_PARM_DESC(stats_current_allocated_bytes, "Memory currently used by statistics");