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[] __counted_by(n_entries);
  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 #define DM_STAT_MAX_ENTRIES             8388608
  70 #define DM_STAT_MAX_HISTOGRAM_ENTRIES   134217728
  71
  72 /*
  73  * A typo on the command line could possibly make the kernel run out of memory
  74  * and crash. To prevent the crash we account all used memory. We fail if we
  75  * exhaust 1/4 of all memory or 1/2 of vmalloc space.
  76  */
  77 #define DM_STATS_MEMORY_FACTOR          4
  78 #define DM_STATS_VMALLOC_FACTOR         2
  79
  80 static DEFINE_SPINLOCK(shared_memory_lock);
  81
  82 static unsigned long shared_memory_amount;
  83
  84 static bool __check_shared_memory(size_t alloc_size)
  85 {
  86         size_t a;
  87
  88         a = shared_memory_amount + alloc_size;
  89         if (a < shared_memory_amount)
  90                 return false;
  91         if (a >> PAGE_SHIFT > totalram_pages() / DM_STATS_MEMORY_FACTOR)
  92                 return false;
  93 #ifdef CONFIG_MMU
  94         if (a > (VMALLOC_END - VMALLOC_START) / DM_STATS_VMALLOC_FACTOR)
  95                 return false;
  96 #endif
  97         return true;
  98 }
  99
 100 static bool check_shared_memory(size_t alloc_size)
 101 {
 102         bool ret;
 103
 104         spin_lock_irq(&shared_memory_lock);
 105
 106         ret = __check_shared_memory(alloc_size);
 107
 108         spin_unlock_irq(&shared_memory_lock);
 109
 110         return ret;
 111 }
 112
 113 static bool claim_shared_memory(size_t alloc_size)
 114 {
 115         spin_lock_irq(&shared_memory_lock);
 116
 117         if (!__check_shared_memory(alloc_size)) {
 118                 spin_unlock_irq(&shared_memory_lock);
 119                 return false;
 120         }
 121
 122         shared_memory_amount += alloc_size;
 123
 124         spin_unlock_irq(&shared_memory_lock);
 125
 126         return true;
 127 }
 128
 129 static void free_shared_memory(size_t alloc_size)
 130 {
 131         unsigned long flags;
 132
 133         spin_lock_irqsave(&shared_memory_lock, flags);
 134
 135         if (WARN_ON_ONCE(shared_memory_amount < alloc_size)) {
 136                 spin_unlock_irqrestore(&shared_memory_lock, flags);
 137                 DMCRIT("Memory usage accounting bug.");
 138                 return;
 139         }
 140
 141         shared_memory_amount -= alloc_size;
 142
 143         spin_unlock_irqrestore(&shared_memory_lock, flags);
 144 }
 145
 146 static void *dm_kvzalloc(size_t alloc_size, int node)
 147 {
 148         void *p;
 149
 150         if (!claim_shared_memory(alloc_size))
 151                 return NULL;
 152
 153         p = kvzalloc_node(alloc_size, GFP_KERNEL | __GFP_NOMEMALLOC, node);
 154         if (p)
 155                 return p;
 156
 157         free_shared_memory(alloc_size);
 158
 159         return NULL;
 160 }
 161
 162 static void dm_kvfree(void *ptr, size_t alloc_size)
 163 {
 164         if (!ptr)
 165                 return;
 166
 167         free_shared_memory(alloc_size);
 168
 169         kvfree(ptr);
 170 }
 171
 172 static void dm_stat_free(struct rcu_head *head)
 173 {
 174         int cpu;
 175         struct dm_stat *s = container_of(head, struct dm_stat, rcu_head);
 176
 177         kfree(s->histogram_boundaries);
 178         kfree(s->program_id);
 179         kfree(s->aux_data);
 180         for_each_possible_cpu(cpu) {
 181                 dm_kvfree(s->stat_percpu[cpu][0].histogram, s->histogram_alloc_size);
 182                 dm_kvfree(s->stat_percpu[cpu], s->percpu_alloc_size);
 183         }
 184         dm_kvfree(s->stat_shared[0].tmp.histogram, s->histogram_alloc_size);
 185         dm_kvfree(s, s->shared_alloc_size);
 186 }
 187
 188 static int dm_stat_in_flight(struct dm_stat_shared *shared)
 189 {
 190         return atomic_read(&shared->in_flight[READ]) +
 191                atomic_read(&shared->in_flight[WRITE]);
 192 }
 193
 194 int dm_stats_init(struct dm_stats *stats)
 195 {
 196         int cpu;
 197         struct dm_stats_last_position *last;
 198
 199         mutex_init(&stats->mutex);
 200         INIT_LIST_HEAD(&stats->list);
 201         stats->precise_timestamps = false;
 202         stats->last = alloc_percpu(struct dm_stats_last_position);
 203         if (!stats->last)
 204                 return -ENOMEM;
 205
 206         for_each_possible_cpu(cpu) {
 207                 last = per_cpu_ptr(stats->last, cpu);
 208                 last->last_sector = (sector_t)ULLONG_MAX;
 209                 last->last_rw = UINT_MAX;
 210         }
 211
 212         return 0;
 213 }
 214
 215 void dm_stats_cleanup(struct dm_stats *stats)
 216 {
 217         size_t ni;
 218         struct dm_stat *s;
 219         struct dm_stat_shared *shared;
 220
 221         while (!list_empty(&stats->list)) {
 222                 s = container_of(stats->list.next, struct dm_stat, list_entry);
 223                 list_del(&s->list_entry);
 224                 for (ni = 0; ni < s->n_entries; ni++) {
 225                         shared = &s->stat_shared[ni];
 226                         if (WARN_ON(dm_stat_in_flight(shared))) {
 227                                 DMCRIT("leaked in-flight counter at index %lu "
 228                                        "(start %llu, end %llu, step %llu): reads %d, writes %d",
 229                                        (unsigned long)ni,
 230                                        (unsigned long long)s->start,
 231                                        (unsigned long long)s->end,
 232                                        (unsigned long long)s->step,
 233                                        atomic_read(&shared->in_flight[READ]),
 234                                        atomic_read(&shared->in_flight[WRITE]));
 235                         }
 236                         cond_resched();
 237                 }
 238                 dm_stat_free(&s->rcu_head);
 239         }
 240         free_percpu(stats->last);
 241         mutex_destroy(&stats->mutex);
 242 }
 243
 244 static void dm_stats_recalc_precise_timestamps(struct dm_stats *stats)
 245 {
 246         struct list_head *l;
 247         struct dm_stat *tmp_s;
 248         bool precise_timestamps = false;
 249
 250         list_for_each(l, &stats->list) {
 251                 tmp_s = container_of(l, struct dm_stat, list_entry);
 252                 if (tmp_s->stat_flags & STAT_PRECISE_TIMESTAMPS) {
 253                         precise_timestamps = true;
 254                         break;
 255                 }
 256         }
 257         stats->precise_timestamps = precise_timestamps;
 258 }
 259
 260 static int dm_stats_create(struct dm_stats *stats, sector_t start, sector_t end,
 261                            sector_t step, unsigned int stat_flags,
 262                            unsigned int n_histogram_entries,
 263                            unsigned long long *histogram_boundaries,
 264                            const char *program_id, const char *aux_data,
 265                            void (*suspend_callback)(struct mapped_device *),
 266                            void (*resume_callback)(struct mapped_device *),
 267                            struct mapped_device *md)
 268 {
 269         struct list_head *l;
 270         struct dm_stat *s, *tmp_s;
 271         sector_t n_entries;
 272         size_t ni;
 273         size_t shared_alloc_size;
 274         size_t percpu_alloc_size;
 275         size_t histogram_alloc_size;
 276         struct dm_stat_percpu *p;
 277         int cpu;
 278         int ret_id;
 279         int r;
 280
 281         if (end < start || !step)
 282                 return -EINVAL;
 283
 284         n_entries = end - start;
 285         if (dm_sector_div64(n_entries, step))
 286                 n_entries++;
 287
 288         if (n_entries != (size_t)n_entries || !(size_t)(n_entries + 1))
 289                 return -EOVERFLOW;
 290
 291         if (n_entries > DM_STAT_MAX_ENTRIES)
 292                 return -EOVERFLOW;
 293
 294         shared_alloc_size = struct_size(s, stat_shared, n_entries);
 295         if ((shared_alloc_size - sizeof(struct dm_stat)) / sizeof(struct dm_stat_shared) != n_entries)
 296                 return -EOVERFLOW;
 297
 298         percpu_alloc_size = (size_t)n_entries * sizeof(struct dm_stat_percpu);
 299         if (percpu_alloc_size / sizeof(struct dm_stat_percpu) != n_entries)
 300                 return -EOVERFLOW;
 301
 302         histogram_alloc_size = (n_histogram_entries + 1) * (size_t)n_entries * sizeof(unsigned long long);
 303         if (histogram_alloc_size / (n_histogram_entries + 1) != (size_t)n_entries * sizeof(unsigned long long))
 304                 return -EOVERFLOW;
 305
 306         if ((n_histogram_entries + 1) * (size_t)n_entries > DM_STAT_MAX_HISTOGRAM_ENTRIES)
 307                 return -EOVERFLOW;
 308
 309         if (!check_shared_memory(shared_alloc_size + histogram_alloc_size +
 310                                  num_possible_cpus() * (percpu_alloc_size + histogram_alloc_size)))
 311                 return -ENOMEM;
 312
 313         s = dm_kvzalloc(shared_alloc_size, NUMA_NO_NODE);
 314         if (!s)
 315                 return -ENOMEM;
 316
 317         s->stat_flags = stat_flags;
 318         s->n_entries = n_entries;
 319         s->start = start;
 320         s->end = end;
 321         s->step = step;
 322         s->shared_alloc_size = shared_alloc_size;
 323         s->percpu_alloc_size = percpu_alloc_size;
 324         s->histogram_alloc_size = histogram_alloc_size;
 325
 326         s->n_histogram_entries = n_histogram_entries;
 327         s->histogram_boundaries = kmemdup(histogram_boundaries,
 328                                           s->n_histogram_entries * sizeof(unsigned long long), GFP_KERNEL);
 329         if (!s->histogram_boundaries) {
 330                 r = -ENOMEM;
 331                 goto out;
 332         }
 333
 334         s->program_id = kstrdup(program_id, GFP_KERNEL);
 335         if (!s->program_id) {
 336                 r = -ENOMEM;
 337                 goto out;
 338         }
 339         s->aux_data = kstrdup(aux_data, GFP_KERNEL);
 340         if (!s->aux_data) {
 341                 r = -ENOMEM;
 342                 goto out;
 343         }
 344
 345         for (ni = 0; ni < n_entries; ni++) {
 346                 atomic_set(&s->stat_shared[ni].in_flight[READ], 0);
 347                 atomic_set(&s->stat_shared[ni].in_flight[WRITE], 0);
 348                 cond_resched();
 349         }
 350
 351         if (s->n_histogram_entries) {
 352                 unsigned long long *hi;
 353
 354                 hi = dm_kvzalloc(s->histogram_alloc_size, NUMA_NO_NODE);
 355                 if (!hi) {
 356                         r = -ENOMEM;
 357                         goto out;
 358                 }
 359                 for (ni = 0; ni < n_entries; ni++) {
 360                         s->stat_shared[ni].tmp.histogram = hi;
 361                         hi += s->n_histogram_entries + 1;
 362                         cond_resched();
 363                 }
 364         }
 365
 366         for_each_possible_cpu(cpu) {
 367                 p = dm_kvzalloc(percpu_alloc_size, cpu_to_node(cpu));
 368                 if (!p) {
 369                         r = -ENOMEM;
 370                         goto out;
 371                 }
 372                 s->stat_percpu[cpu] = p;
 373                 if (s->n_histogram_entries) {
 374                         unsigned long long *hi;
 375
 376                         hi = dm_kvzalloc(s->histogram_alloc_size, cpu_to_node(cpu));
 377                         if (!hi) {
 378                                 r = -ENOMEM;
 379                                 goto out;
 380                         }
 381                         for (ni = 0; ni < n_entries; ni++) {
 382                                 p[ni].histogram = hi;
 383                                 hi += s->n_histogram_entries + 1;
 384                                 cond_resched();
 385                         }
 386                 }
 387         }
 388
 389         /*
 390          * Suspend/resume to make sure there is no i/o in flight,
 391          * so that newly created statistics will be exact.
 392          *
 393          * (note: we couldn't suspend earlier because we must not
 394          * allocate memory while suspended)
 395          */
 396         suspend_callback(md);
 397
 398         mutex_lock(&stats->mutex);
 399         s->id = 0;
 400         list_for_each(l, &stats->list) {
 401                 tmp_s = container_of(l, struct dm_stat, list_entry);
 402                 if (WARN_ON(tmp_s->id < s->id)) {
 403                         r = -EINVAL;
 404                         goto out_unlock_resume;
 405                 }
 406                 if (tmp_s->id > s->id)
 407                         break;
 408                 if (unlikely(s->id == INT_MAX)) {
 409                         r = -ENFILE;
 410                         goto out_unlock_resume;
 411                 }
 412                 s->id++;
 413         }
 414         ret_id = s->id;
 415         list_add_tail_rcu(&s->list_entry, l);
 416
 417         dm_stats_recalc_precise_timestamps(stats);
 418
 419         if (!static_key_enabled(&stats_enabled.key))
 420                 static_branch_enable(&stats_enabled);
 421
 422         mutex_unlock(&stats->mutex);
 423
 424         resume_callback(md);
 425
 426         return ret_id;
 427
 428 out_unlock_resume:
 429         mutex_unlock(&stats->mutex);
 430         resume_callback(md);
 431 out:
 432         dm_stat_free(&s->rcu_head);
 433         return r;
 434 }
 435
 436 static struct dm_stat *__dm_stats_find(struct dm_stats *stats, int id)
 437 {
 438         struct dm_stat *s;
 439
 440         list_for_each_entry(s, &stats->list, list_entry) {
 441                 if (s->id > id)
 442                         break;
 443                 if (s->id == id)
 444                         return s;
 445         }
 446
 447         return NULL;
 448 }
 449
 450 static int dm_stats_delete(struct dm_stats *stats, int id)
 451 {
 452         struct dm_stat *s;
 453         int cpu;
 454
 455         mutex_lock(&stats->mutex);
 456
 457         s = __dm_stats_find(stats, id);
 458         if (!s) {
 459                 mutex_unlock(&stats->mutex);
 460                 return -ENOENT;
 461         }
 462
 463         list_del_rcu(&s->list_entry);
 464
 465         dm_stats_recalc_precise_timestamps(stats);
 466
 467         mutex_unlock(&stats->mutex);
 468
 469         /*
 470          * vfree can't be called from RCU callback
 471          */
 472         for_each_possible_cpu(cpu)
 473                 if (is_vmalloc_addr(s->stat_percpu) ||
 474                     is_vmalloc_addr(s->stat_percpu[cpu][0].histogram))
 475                         goto do_sync_free;
 476         if (is_vmalloc_addr(s) ||
 477             is_vmalloc_addr(s->stat_shared[0].tmp.histogram)) {
 478 do_sync_free:
 479                 synchronize_rcu_expedited();
 480                 dm_stat_free(&s->rcu_head);
 481         } else {
 482                 WRITE_ONCE(dm_stat_need_rcu_barrier, 1);
 483                 call_rcu(&s->rcu_head, dm_stat_free);
 484         }
 485         return 0;
 486 }
 487
 488 static int dm_stats_list(struct dm_stats *stats, const char *program,
 489                          char *result, unsigned int maxlen)
 490 {
 491         struct dm_stat *s;
 492         sector_t len;
 493         unsigned int sz = 0;
 494
 495         /*
 496          * Output format:
 497          *   <region_id>: <start_sector>+<length> <step> <program_id> <aux_data>
 498          */
 499
 500         mutex_lock(&stats->mutex);
 501         list_for_each_entry(s, &stats->list, list_entry) {
 502                 if (!program || !strcmp(program, s->program_id)) {
 503                         len = s->end - s->start;
 504                         DMEMIT("%d: %llu+%llu %llu %s %s", s->id,
 505                                 (unsigned long long)s->start,
 506                                 (unsigned long long)len,
 507                                 (unsigned long long)s->step,
 508                                 s->program_id,
 509                                 s->aux_data);
 510                         if (s->stat_flags & STAT_PRECISE_TIMESTAMPS)
 511                                 DMEMIT(" precise_timestamps");
 512                         if (s->n_histogram_entries) {
 513                                 unsigned int i;
 514
 515                                 DMEMIT(" histogram:");
 516                                 for (i = 0; i < s->n_histogram_entries; i++) {
 517                                         if (i)
 518                                                 DMEMIT(",");
 519                                         DMEMIT("%llu", s->histogram_boundaries[i]);
 520                                 }
 521                         }
 522                         DMEMIT("\n");
 523                 }
 524                 cond_resched();
 525         }
 526         mutex_unlock(&stats->mutex);
 527
 528         return 1;
 529 }
 530
 531 static void dm_stat_round(struct dm_stat *s, struct dm_stat_shared *shared,
 532                           struct dm_stat_percpu *p)
 533 {
 534         /*
 535          * This is racy, but so is part_round_stats_single.
 536          */
 537         unsigned long long now, difference;
 538         unsigned int in_flight_read, in_flight_write;
 539
 540         if (likely(!(s->stat_flags & STAT_PRECISE_TIMESTAMPS)))
 541                 now = jiffies;
 542         else
 543                 now = ktime_to_ns(ktime_get());
 544
 545         difference = now - shared->stamp;
 546         if (!difference)
 547                 return;
 548
 549         in_flight_read = (unsigned int)atomic_read(&shared->in_flight[READ]);
 550         in_flight_write = (unsigned int)atomic_read(&shared->in_flight[WRITE]);
 551         if (in_flight_read)
 552                 p->io_ticks[READ] += difference;
 553         if (in_flight_write)
 554                 p->io_ticks[WRITE] += difference;
 555         if (in_flight_read + in_flight_write) {
 556                 p->io_ticks_total += difference;
 557                 p->time_in_queue += (in_flight_read + in_flight_write) * difference;
 558         }
 559         shared->stamp = now;
 560 }
 561
 562 static void dm_stat_for_entry(struct dm_stat *s, size_t entry,
 563                               int idx, sector_t len,
 564                               struct dm_stats_aux *stats_aux, bool end,
 565                               unsigned long duration_jiffies)
 566 {
 567         struct dm_stat_shared *shared = &s->stat_shared[entry];
 568         struct dm_stat_percpu *p;
 569
 570         /*
 571          * For strict correctness we should use local_irq_save/restore
 572          * instead of preempt_disable/enable.
 573          *
 574          * preempt_disable/enable is racy if the driver finishes bios
 575          * from non-interrupt context as well as from interrupt context
 576          * or from more different interrupts.
 577          *
 578          * On 64-bit architectures the race only results in not counting some
 579          * events, so it is acceptable.  On 32-bit architectures the race could
 580          * cause the counter going off by 2^32, so we need to do proper locking
 581          * there.
 582          *
 583          * part_stat_lock()/part_stat_unlock() have this race too.
 584          */
 585 #if BITS_PER_LONG == 32
 586         unsigned long flags;
 587
 588         local_irq_save(flags);
 589 #else
 590         preempt_disable();
 591 #endif
 592         p = &s->stat_percpu[smp_processor_id()][entry];
 593
 594         if (!end) {
 595                 dm_stat_round(s, shared, p);
 596                 atomic_inc(&shared->in_flight[idx]);
 597         } else {
 598                 unsigned long long duration;
 599
 600                 dm_stat_round(s, shared, p);
 601                 atomic_dec(&shared->in_flight[idx]);
 602                 p->sectors[idx] += len;
 603                 p->ios[idx] += 1;
 604                 p->merges[idx] += stats_aux->merged;
 605                 if (!(s->stat_flags & STAT_PRECISE_TIMESTAMPS)) {
 606                         p->ticks[idx] += duration_jiffies;
 607                         duration = jiffies_to_msecs(duration_jiffies);
 608                 } else {
 609                         p->ticks[idx] += stats_aux->duration_ns;
 610                         duration = stats_aux->duration_ns;
 611                 }
 612                 if (s->n_histogram_entries) {
 613                         unsigned int lo = 0, hi = s->n_histogram_entries + 1;
 614
 615                         while (lo + 1 < hi) {
 616                                 unsigned int mid = (lo + hi) / 2;
 617
 618                                 if (s->histogram_boundaries[mid - 1] > duration)
 619                                         hi = mid;
 620                                 else
 621                                         lo = mid;
 622                         }
 623                         p->histogram[lo]++;
 624                 }
 625         }
 626
 627 #if BITS_PER_LONG == 32
 628         local_irq_restore(flags);
 629 #else
 630         preempt_enable();
 631 #endif
 632 }
 633
 634 static void __dm_stat_bio(struct dm_stat *s, int bi_rw,
 635                           sector_t bi_sector, sector_t end_sector,
 636                           bool end, unsigned long duration_jiffies,
 637                           struct dm_stats_aux *stats_aux)
 638 {
 639         sector_t rel_sector, offset, todo, fragment_len;
 640         size_t entry;
 641
 642         if (end_sector <= s->start || bi_sector >= s->end)
 643                 return;
 644         if (unlikely(bi_sector < s->start)) {
 645                 rel_sector = 0;
 646                 todo = end_sector - s->start;
 647         } else {
 648                 rel_sector = bi_sector - s->start;
 649                 todo = end_sector - bi_sector;
 650         }
 651         if (unlikely(end_sector > s->end))
 652                 todo -= (end_sector - s->end);
 653
 654         offset = dm_sector_div64(rel_sector, s->step);
 655         entry = rel_sector;
 656         do {
 657                 if (WARN_ON_ONCE(entry >= s->n_entries)) {
 658                         DMCRIT("Invalid area access in region id %d", s->id);
 659                         return;
 660                 }
 661                 fragment_len = todo;
 662                 if (fragment_len > s->step - offset)
 663                         fragment_len = s->step - offset;
 664                 dm_stat_for_entry(s, entry, bi_rw, fragment_len,
 665                                   stats_aux, end, duration_jiffies);
 666                 todo -= fragment_len;
 667                 entry++;
 668                 offset = 0;
 669         } while (unlikely(todo != 0));
 670 }
 671
 672 void dm_stats_account_io(struct dm_stats *stats, unsigned long bi_rw,
 673                          sector_t bi_sector, unsigned int bi_sectors, bool end,
 674                          unsigned long start_time,
 675                          struct dm_stats_aux *stats_aux)
 676 {
 677         struct dm_stat *s;
 678         sector_t end_sector;
 679         struct dm_stats_last_position *last;
 680         bool got_precise_time;
 681         unsigned long duration_jiffies = 0;
 682
 683         if (unlikely(!bi_sectors))
 684                 return;
 685
 686         end_sector = bi_sector + bi_sectors;
 687
 688         if (!end) {
 689                 /*
 690                  * A race condition can at worst result in the merged flag being
 691                  * misrepresented, so we don't have to disable preemption here.
 692                  */
 693                 last = raw_cpu_ptr(stats->last);
 694                 stats_aux->merged =
 695                         (bi_sector == (READ_ONCE(last->last_sector) &&
 696                                        ((bi_rw == WRITE) ==
 697                                         (READ_ONCE(last->last_rw) == WRITE))
 698                                        ));
 699                 WRITE_ONCE(last->last_sector, end_sector);
 700                 WRITE_ONCE(last->last_rw, bi_rw);
 701         } else
 702                 duration_jiffies = jiffies - start_time;
 703
 704         rcu_read_lock();
 705
 706         got_precise_time = false;
 707         list_for_each_entry_rcu(s, &stats->list, list_entry) {
 708                 if (s->stat_flags & STAT_PRECISE_TIMESTAMPS && !got_precise_time) {
 709                         /* start (!end) duration_ns is set by DM core's alloc_io() */
 710                         if (end)
 711                                 stats_aux->duration_ns = ktime_to_ns(ktime_get()) - stats_aux->duration_ns;
 712                         got_precise_time = true;
 713                 }
 714                 __dm_stat_bio(s, bi_rw, bi_sector, end_sector, end, duration_jiffies, stats_aux);
 715         }
 716
 717         rcu_read_unlock();
 718 }
 719
 720 static void __dm_stat_init_temporary_percpu_totals(struct dm_stat_shared *shared,
 721                                                    struct dm_stat *s, size_t x)
 722 {
 723         int cpu;
 724         struct dm_stat_percpu *p;
 725
 726         local_irq_disable();
 727         p = &s->stat_percpu[smp_processor_id()][x];
 728         dm_stat_round(s, shared, p);
 729         local_irq_enable();
 730
 731         shared->tmp.sectors[READ] = 0;
 732         shared->tmp.sectors[WRITE] = 0;
 733         shared->tmp.ios[READ] = 0;
 734         shared->tmp.ios[WRITE] = 0;
 735         shared->tmp.merges[READ] = 0;
 736         shared->tmp.merges[WRITE] = 0;
 737         shared->tmp.ticks[READ] = 0;
 738         shared->tmp.ticks[WRITE] = 0;
 739         shared->tmp.io_ticks[READ] = 0;
 740         shared->tmp.io_ticks[WRITE] = 0;
 741         shared->tmp.io_ticks_total = 0;
 742         shared->tmp.time_in_queue = 0;
 743
 744         if (s->n_histogram_entries)
 745                 memset(shared->tmp.histogram, 0, (s->n_histogram_entries + 1) * sizeof(unsigned long long));
 746
 747         for_each_possible_cpu(cpu) {
 748                 p = &s->stat_percpu[cpu][x];
 749                 shared->tmp.sectors[READ] += READ_ONCE(p->sectors[READ]);
 750                 shared->tmp.sectors[WRITE] += READ_ONCE(p->sectors[WRITE]);
 751                 shared->tmp.ios[READ] += READ_ONCE(p->ios[READ]);
 752                 shared->tmp.ios[WRITE] += READ_ONCE(p->ios[WRITE]);
 753                 shared->tmp.merges[READ] += READ_ONCE(p->merges[READ]);
 754                 shared->tmp.merges[WRITE] += READ_ONCE(p->merges[WRITE]);
 755                 shared->tmp.ticks[READ] += READ_ONCE(p->ticks[READ]);
 756                 shared->tmp.ticks[WRITE] += READ_ONCE(p->ticks[WRITE]);
 757                 shared->tmp.io_ticks[READ] += READ_ONCE(p->io_ticks[READ]);
 758                 shared->tmp.io_ticks[WRITE] += READ_ONCE(p->io_ticks[WRITE]);
 759                 shared->tmp.io_ticks_total += READ_ONCE(p->io_ticks_total);
 760                 shared->tmp.time_in_queue += READ_ONCE(p->time_in_queue);
 761                 if (s->n_histogram_entries) {
 762                         unsigned int i;
 763
 764                         for (i = 0; i < s->n_histogram_entries + 1; i++)
 765                                 shared->tmp.histogram[i] += READ_ONCE(p->histogram[i]);
 766                 }
 767         }
 768 }
 769
 770 static void __dm_stat_clear(struct dm_stat *s, size_t idx_start, size_t idx_end,
 771                             bool init_tmp_percpu_totals)
 772 {
 773         size_t x;
 774         struct dm_stat_shared *shared;
 775         struct dm_stat_percpu *p;
 776
 777         for (x = idx_start; x < idx_end; x++) {
 778                 shared = &s->stat_shared[x];
 779                 if (init_tmp_percpu_totals)
 780                         __dm_stat_init_temporary_percpu_totals(shared, s, x);
 781                 local_irq_disable();
 782                 p = &s->stat_percpu[smp_processor_id()][x];
 783                 p->sectors[READ] -= shared->tmp.sectors[READ];
 784                 p->sectors[WRITE] -= shared->tmp.sectors[WRITE];
 785                 p->ios[READ] -= shared->tmp.ios[READ];
 786                 p->ios[WRITE] -= shared->tmp.ios[WRITE];
 787                 p->merges[READ] -= shared->tmp.merges[READ];
 788                 p->merges[WRITE] -= shared->tmp.merges[WRITE];
 789                 p->ticks[READ] -= shared->tmp.ticks[READ];
 790                 p->ticks[WRITE] -= shared->tmp.ticks[WRITE];
 791                 p->io_ticks[READ] -= shared->tmp.io_ticks[READ];
 792                 p->io_ticks[WRITE] -= shared->tmp.io_ticks[WRITE];
 793                 p->io_ticks_total -= shared->tmp.io_ticks_total;
 794                 p->time_in_queue -= shared->tmp.time_in_queue;
 795                 local_irq_enable();
 796                 if (s->n_histogram_entries) {
 797                         unsigned int i;
 798
 799                         for (i = 0; i < s->n_histogram_entries + 1; i++) {
 800                                 local_irq_disable();
 801                                 p = &s->stat_percpu[smp_processor_id()][x];
 802                                 p->histogram[i] -= shared->tmp.histogram[i];
 803                                 local_irq_enable();
 804                         }
 805                 }
 806                 cond_resched();
 807         }
 808 }
 809
 810 static int dm_stats_clear(struct dm_stats *stats, int id)
 811 {
 812         struct dm_stat *s;
 813
 814         mutex_lock(&stats->mutex);
 815
 816         s = __dm_stats_find(stats, id);
 817         if (!s) {
 818                 mutex_unlock(&stats->mutex);
 819                 return -ENOENT;
 820         }
 821
 822         __dm_stat_clear(s, 0, s->n_entries, true);
 823
 824         mutex_unlock(&stats->mutex);
 825
 826         return 1;
 827 }
 828
 829 /*
 830  * This is like jiffies_to_msec, but works for 64-bit values.
 831  */
 832 static unsigned long long dm_jiffies_to_msec64(struct dm_stat *s, unsigned long long j)
 833 {
 834         unsigned long long result;
 835         unsigned int mult;
 836
 837         if (s->stat_flags & STAT_PRECISE_TIMESTAMPS)
 838                 return j;
 839
 840         result = 0;
 841         if (j)
 842                 result = jiffies_to_msecs(j & 0x3fffff);
 843         if (j >= 1 << 22) {
 844                 mult = jiffies_to_msecs(1 << 22);
 845                 result += (unsigned long long)mult * (unsigned long long)jiffies_to_msecs((j >> 22) & 0x3fffff);
 846         }
 847         if (j >= 1ULL << 44)
 848                 result += (unsigned long long)mult * (unsigned long long)mult * (unsigned long long)jiffies_to_msecs(j >> 44);
 849
 850         return result;
 851 }
 852
 853 static int dm_stats_print(struct dm_stats *stats, int id,
 854                           size_t idx_start, size_t idx_len,
 855                           bool clear, char *result, unsigned int maxlen)
 856 {
 857         unsigned int sz = 0;
 858         struct dm_stat *s;
 859         size_t x;
 860         sector_t start, end, step;
 861         size_t idx_end;
 862         struct dm_stat_shared *shared;
 863
 864         /*
 865          * Output format:
 866          *   <start_sector>+<length> counters
 867          */
 868
 869         mutex_lock(&stats->mutex);
 870
 871         s = __dm_stats_find(stats, id);
 872         if (!s) {
 873                 mutex_unlock(&stats->mutex);
 874                 return -ENOENT;
 875         }
 876
 877         idx_end = idx_start + idx_len;
 878         if (idx_end < idx_start ||
 879             idx_end > s->n_entries)
 880                 idx_end = s->n_entries;
 881
 882         if (idx_start > idx_end)
 883                 idx_start = idx_end;
 884
 885         step = s->step;
 886         start = s->start + (step * idx_start);
 887
 888         for (x = idx_start; x < idx_end; x++, start = end) {
 889                 shared = &s->stat_shared[x];
 890                 end = start + step;
 891                 if (unlikely(end > s->end))
 892                         end = s->end;
 893
 894                 __dm_stat_init_temporary_percpu_totals(shared, s, x);
 895
 896                 DMEMIT("%llu+%llu %llu %llu %llu %llu %llu %llu %llu %llu %d %llu %llu %llu %llu",
 897                        (unsigned long long)start,
 898                        (unsigned long long)step,
 899                        shared->tmp.ios[READ],
 900                        shared->tmp.merges[READ],
 901                        shared->tmp.sectors[READ],
 902                        dm_jiffies_to_msec64(s, shared->tmp.ticks[READ]),
 903                        shared->tmp.ios[WRITE],
 904                        shared->tmp.merges[WRITE],
 905                        shared->tmp.sectors[WRITE],
 906                        dm_jiffies_to_msec64(s, shared->tmp.ticks[WRITE]),
 907                        dm_stat_in_flight(shared),
 908                        dm_jiffies_to_msec64(s, shared->tmp.io_ticks_total),
 909                        dm_jiffies_to_msec64(s, shared->tmp.time_in_queue),
 910                        dm_jiffies_to_msec64(s, shared->tmp.io_ticks[READ]),
 911                        dm_jiffies_to_msec64(s, shared->tmp.io_ticks[WRITE]));
 912                 if (s->n_histogram_entries) {
 913                         unsigned int i;
 914
 915                         for (i = 0; i < s->n_histogram_entries + 1; i++)
 916                                 DMEMIT("%s%llu", !i ? " " : ":", shared->tmp.histogram[i]);
 917                 }
 918                 DMEMIT("\n");
 919
 920                 if (unlikely(sz + 1 >= maxlen))
 921                         goto buffer_overflow;
 922
 923                 cond_resched();
 924         }
 925
 926         if (clear)
 927                 __dm_stat_clear(s, idx_start, idx_end, false);
 928
 929 buffer_overflow:
 930         mutex_unlock(&stats->mutex);
 931
 932         return 1;
 933 }
 934
 935 static int dm_stats_set_aux(struct dm_stats *stats, int id, const char *aux_data)
 936 {
 937         struct dm_stat *s;
 938         const char *new_aux_data;
 939
 940         mutex_lock(&stats->mutex);
 941
 942         s = __dm_stats_find(stats, id);
 943         if (!s) {
 944                 mutex_unlock(&stats->mutex);
 945                 return -ENOENT;
 946         }
 947
 948         new_aux_data = kstrdup(aux_data, GFP_KERNEL);
 949         if (!new_aux_data) {
 950                 mutex_unlock(&stats->mutex);
 951                 return -ENOMEM;
 952         }
 953
 954         kfree(s->aux_data);
 955         s->aux_data = new_aux_data;
 956
 957         mutex_unlock(&stats->mutex);
 958
 959         return 0;
 960 }
 961
 962 static int parse_histogram(const char *h, unsigned int *n_histogram_entries,
 963                            unsigned long long **histogram_boundaries)
 964 {
 965         const char *q;
 966         unsigned int n;
 967         unsigned long long last;
 968
 969         *n_histogram_entries = 1;
 970         for (q = h; *q; q++)
 971                 if (*q == ',')
 972                         (*n_histogram_entries)++;
 973
 974         *histogram_boundaries = kmalloc_array(*n_histogram_entries,
 975                                               sizeof(unsigned long long),
 976                                               GFP_KERNEL);
 977         if (!*histogram_boundaries)
 978                 return -ENOMEM;
 979
 980         n = 0;
 981         last = 0;
 982         while (1) {
 983                 unsigned long long hi;
 984                 int s;
 985                 char ch;
 986
 987                 s = sscanf(h, "%llu%c", &hi, &ch);
 988                 if (!s || (s == 2 && ch != ','))
 989                         return -EINVAL;
 990                 if (hi <= last)
 991                         return -EINVAL;
 992                 last = hi;
 993                 (*histogram_boundaries)[n] = hi;
 994                 if (s == 1)
 995                         return 0;
 996                 h = strchr(h, ',') + 1;
 997                 n++;
 998         }
 999 }
1000
1001 static int message_stats_create(struct mapped_device *md,
1002                                 unsigned int argc, char **argv,
1003                                 char *result, unsigned int maxlen)
1004 {
1005         int r;
1006         int id;
1007         char dummy;
1008         unsigned long long start, end, len, step;
1009         unsigned int divisor;
1010         const char *program_id, *aux_data;
1011         unsigned int stat_flags = 0;
1012         unsigned int n_histogram_entries = 0;
1013         unsigned long long *histogram_boundaries = NULL;
1014         struct dm_arg_set as, as_backup;
1015         const char *a;
1016         unsigned int feature_args;
1017
1018         /*
1019          * Input format:
1020          *   <range> <step> [<extra_parameters> <parameters>] [<program_id> [<aux_data>]]
1021          */
1022
1023         if (argc < 3)
1024                 goto ret_einval;
1025
1026         as.argc = argc;
1027         as.argv = argv;
1028         dm_consume_args(&as, 1);
1029
1030         a = dm_shift_arg(&as);
1031         if (!strcmp(a, "-")) {
1032                 start = 0;
1033                 len = dm_get_size(md);
1034                 if (!len)
1035                         len = 1;
1036         } else if (sscanf(a, "%llu+%llu%c", &start, &len, &dummy) != 2 ||
1037                    start != (sector_t)start || len != (sector_t)len)
1038                 goto ret_einval;
1039
1040         end = start + len;
1041         if (start >= end)
1042                 goto ret_einval;
1043
1044         a = dm_shift_arg(&as);
1045         if (sscanf(a, "/%u%c", &divisor, &dummy) == 1) {
1046                 if (!divisor)
1047                         return -EINVAL;
1048                 step = end - start;
1049                 if (do_div(step, divisor))
1050                         step++;
1051                 if (!step)
1052                         step = 1;
1053         } else if (sscanf(a, "%llu%c", &step, &dummy) != 1 ||
1054                    step != (sector_t)step || !step)
1055                 goto ret_einval;
1056
1057         as_backup = as;
1058         a = dm_shift_arg(&as);
1059         if (a && sscanf(a, "%u%c", &feature_args, &dummy) == 1) {
1060                 while (feature_args--) {
1061                         a = dm_shift_arg(&as);
1062                         if (!a)
1063                                 goto ret_einval;
1064                         if (!strcasecmp(a, "precise_timestamps"))
1065                                 stat_flags |= STAT_PRECISE_TIMESTAMPS;
1066                         else if (!strncasecmp(a, "histogram:", 10)) {
1067                                 if (n_histogram_entries)
1068                                         goto ret_einval;
1069                                 r = parse_histogram(a + 10, &n_histogram_entries, &histogram_boundaries);
1070                                 if (r)
1071                                         goto ret;
1072                         } else
1073                                 goto ret_einval;
1074                 }
1075         } else {
1076                 as = as_backup;
1077         }
1078
1079         program_id = "-";
1080         aux_data = "-";
1081
1082         a = dm_shift_arg(&as);
1083         if (a)
1084                 program_id = a;
1085
1086         a = dm_shift_arg(&as);
1087         if (a)
1088                 aux_data = a;
1089
1090         if (as.argc)
1091                 goto ret_einval;
1092
1093         /*
1094          * If a buffer overflow happens after we created the region,
1095          * it's too late (the userspace would retry with a larger
1096          * buffer, but the region id that caused the overflow is already
1097          * leaked).  So we must detect buffer overflow in advance.
1098          */
1099         snprintf(result, maxlen, "%d", INT_MAX);
1100         if (dm_message_test_buffer_overflow(result, maxlen)) {
1101                 r = 1;
1102                 goto ret;
1103         }
1104
1105         id = dm_stats_create(dm_get_stats(md), start, end, step, stat_flags,
1106                              n_histogram_entries, histogram_boundaries, program_id, aux_data,
1107                              dm_internal_suspend_fast, dm_internal_resume_fast, md);
1108         if (id < 0) {
1109                 r = id;
1110                 goto ret;
1111         }
1112
1113         snprintf(result, maxlen, "%d", id);
1114
1115         r = 1;
1116         goto ret;
1117
1118 ret_einval:
1119         r = -EINVAL;
1120 ret:
1121         kfree(histogram_boundaries);
1122         return r;
1123 }
1124
1125 static int message_stats_delete(struct mapped_device *md,
1126                                 unsigned int argc, char **argv)
1127 {
1128         int id;
1129         char dummy;
1130
1131         if (argc != 2)
1132                 return -EINVAL;
1133
1134         if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
1135                 return -EINVAL;
1136
1137         return dm_stats_delete(dm_get_stats(md), id);
1138 }
1139
1140 static int message_stats_clear(struct mapped_device *md,
1141                                unsigned int argc, char **argv)
1142 {
1143         int id;
1144         char dummy;
1145
1146         if (argc != 2)
1147                 return -EINVAL;
1148
1149         if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
1150                 return -EINVAL;
1151
1152         return dm_stats_clear(dm_get_stats(md), id);
1153 }
1154
1155 static int message_stats_list(struct mapped_device *md,
1156                               unsigned int argc, char **argv,
1157                               char *result, unsigned int maxlen)
1158 {
1159         int r;
1160         const char *program = NULL;
1161
1162         if (argc < 1 || argc > 2)
1163                 return -EINVAL;
1164
1165         if (argc > 1) {
1166                 program = kstrdup(argv[1], GFP_KERNEL);
1167                 if (!program)
1168                         return -ENOMEM;
1169         }
1170
1171         r = dm_stats_list(dm_get_stats(md), program, result, maxlen);
1172
1173         kfree(program);
1174
1175         return r;
1176 }
1177
1178 static int message_stats_print(struct mapped_device *md,
1179                                unsigned int argc, char **argv, bool clear,
1180                                char *result, unsigned int maxlen)
1181 {
1182         int id;
1183         char dummy;
1184         unsigned long idx_start = 0, idx_len = ULONG_MAX;
1185
1186         if (argc != 2 && argc != 4)
1187                 return -EINVAL;
1188
1189         if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
1190                 return -EINVAL;
1191
1192         if (argc > 3) {
1193                 if (strcmp(argv[2], "-") &&
1194                     sscanf(argv[2], "%lu%c", &idx_start, &dummy) != 1)
1195                         return -EINVAL;
1196                 if (strcmp(argv[3], "-") &&
1197                     sscanf(argv[3], "%lu%c", &idx_len, &dummy) != 1)
1198                         return -EINVAL;
1199         }
1200
1201         return dm_stats_print(dm_get_stats(md), id, idx_start, idx_len, clear,
1202                               result, maxlen);
1203 }
1204
1205 static int message_stats_set_aux(struct mapped_device *md,
1206                                  unsigned int argc, char **argv)
1207 {
1208         int id;
1209         char dummy;
1210
1211         if (argc != 3)
1212                 return -EINVAL;
1213
1214         if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
1215                 return -EINVAL;
1216
1217         return dm_stats_set_aux(dm_get_stats(md), id, argv[2]);
1218 }
1219
1220 int dm_stats_message(struct mapped_device *md, unsigned int argc, char **argv,
1221                      char *result, unsigned int maxlen)
1222 {
1223         int r;
1224
1225         /* All messages here must start with '@' */
1226         if (!strcasecmp(argv[0], "@stats_create"))
1227                 r = message_stats_create(md, argc, argv, result, maxlen);
1228         else if (!strcasecmp(argv[0], "@stats_delete"))
1229                 r = message_stats_delete(md, argc, argv);
1230         else if (!strcasecmp(argv[0], "@stats_clear"))
1231                 r = message_stats_clear(md, argc, argv);
1232         else if (!strcasecmp(argv[0], "@stats_list"))
1233                 r = message_stats_list(md, argc, argv, result, maxlen);
1234         else if (!strcasecmp(argv[0], "@stats_print"))
1235                 r = message_stats_print(md, argc, argv, false, result, maxlen);
1236         else if (!strcasecmp(argv[0], "@stats_print_clear"))
1237                 r = message_stats_print(md, argc, argv, true, result, maxlen);
1238         else if (!strcasecmp(argv[0], "@stats_set_aux"))
1239                 r = message_stats_set_aux(md, argc, argv);
1240         else
1241                 return 2; /* this wasn't a stats message */
1242
1243         if (r == -EINVAL)
1244                 DMCRIT("Invalid parameters for message %s", argv[0]);
1245
1246         return r;
1247 }
1248
1249 int __init dm_statistics_init(void)
1250 {
1251         shared_memory_amount = 0;
1252         dm_stat_need_rcu_barrier = 0;
1253         return 0;
1254 }
1255
1256 void dm_statistics_exit(void)
1257 {
1258         if (dm_stat_need_rcu_barrier)
1259                 rcu_barrier();
1260         if (WARN_ON(shared_memory_amount))
1261                 DMCRIT("shared_memory_amount leaked: %lu", shared_memory_amount);
1262 }
1263
1264 module_param_named(stats_current_allocated_bytes, shared_memory_amount, ulong, 0444);
1265 MODULE_PARM_DESC(stats_current_allocated_bytes, "Memory currently used by statistics");