drivers/md/dm-stats.c

   1 #include <linux/errno.h>
   2 #include <linux/numa.h>
   3 #include <linux/slab.h>
   4 #include <linux/rculist.h>
   5 #include <linux/threads.h>
   6 #include <linux/preempt.h>
   7 #include <linux/irqflags.h>
   8 #include <linux/vmalloc.h>
   9 #include <linux/mm.h>
  10 #include <linux/module.h>
  11 #include <linux/device-mapper.h>
  12
  13 #include "dm-core.h"
  14 #include "dm-stats.h"
  15
  16 #define DM_MSG_PREFIX "stats"
  17
  18 static int dm_stat_need_rcu_barrier;
  19
  20 /*
  21  * Using 64-bit values to avoid overflow (which is a
  22  * problem that block/genhd.c's IO accounting has).
  23  */
  24 struct dm_stat_percpu {
  25         unsigned long long sectors[2];
  26         unsigned long long ios[2];
  27         unsigned long long merges[2];
  28         unsigned long long ticks[2];
  29         unsigned long long io_ticks[2];
  30         unsigned long long io_ticks_total;
  31         unsigned long long time_in_queue;
  32         unsigned long long *histogram;
  33 };
  34
  35 struct dm_stat_shared {
  36         atomic_t in_flight[2];
  37         unsigned long long stamp;
  38         struct dm_stat_percpu tmp;
  39 };
  40
  41 struct dm_stat {
  42         struct list_head list_entry;
  43         int id;
  44         unsigned stat_flags;
  45         size_t n_entries;
  46         sector_t start;
  47         sector_t end;
  48         sector_t step;
  49         unsigned n_histogram_entries;
  50         unsigned long long *histogram_boundaries;
  51         const char *program_id;
  52         const char *aux_data;
  53         struct rcu_head rcu_head;
  54         size_t shared_alloc_size;
  55         size_t percpu_alloc_size;
  56         size_t histogram_alloc_size;
  57         struct dm_stat_percpu *stat_percpu[NR_CPUS];
  58         struct dm_stat_shared stat_shared[0];
  59 };
  60
  61 #define STAT_PRECISE_TIMESTAMPS         1
  62
  63 struct dm_stats_last_position {
  64         sector_t last_sector;
  65         unsigned last_rw;
  66 };
  67
  68 /*
  69  * A typo on the command line could possibly make the kernel run out of memory
  70  * and crash. To prevent the crash we account all used memory. We fail if we
  71  * exhaust 1/4 of all memory or 1/2 of vmalloc space.
  72  */
  73 #define DM_STATS_MEMORY_FACTOR          4
  74 #define DM_STATS_VMALLOC_FACTOR         2
  75
  76 static DEFINE_SPINLOCK(shared_memory_lock);
  77
  78 static unsigned long shared_memory_amount;
  79
  80 static bool __check_shared_memory(size_t alloc_size)
  81 {
  82         size_t a;
  83
  84         a = shared_memory_amount + alloc_size;
  85         if (a < shared_memory_amount)
  86                 return false;
  87         if (a >> PAGE_SHIFT > totalram_pages / DM_STATS_MEMORY_FACTOR)
  88                 return false;
  89 #ifdef CONFIG_MMU
  90         if (a > (VMALLOC_END - VMALLOC_START) / DM_STATS_VMALLOC_FACTOR)
  91                 return false;
  92 #endif
  93         return true;
  94 }
  95
  96 static bool check_shared_memory(size_t alloc_size)
  97 {
  98         bool ret;
  99
 100         spin_lock_irq(&shared_memory_lock);
 101
 102         ret = __check_shared_memory(alloc_size);
 103
 104         spin_unlock_irq(&shared_memory_lock);
 105
 106         return ret;
 107 }
 108
 109 static bool claim_shared_memory(size_t alloc_size)
 110 {
 111         spin_lock_irq(&shared_memory_lock);
 112
 113         if (!__check_shared_memory(alloc_size)) {
 114                 spin_unlock_irq(&shared_memory_lock);
 115                 return false;
 116         }
 117
 118         shared_memory_amount += alloc_size;
 119
 120         spin_unlock_irq(&shared_memory_lock);
 121
 122         return true;
 123 }
 124
 125 static void free_shared_memory(size_t alloc_size)
 126 {
 127         unsigned long flags;
 128
 129         spin_lock_irqsave(&shared_memory_lock, flags);
 130
 131         if (WARN_ON_ONCE(shared_memory_amount < alloc_size)) {
 132                 spin_unlock_irqrestore(&shared_memory_lock, flags);
 133                 DMCRIT("Memory usage accounting bug.");
 134                 return;
 135         }
 136
 137         shared_memory_amount -= alloc_size;
 138
 139         spin_unlock_irqrestore(&shared_memory_lock, flags);
 140 }
 141
 142 static void *dm_kvzalloc(size_t alloc_size, int node)
 143 {
 144         void *p;
 145
 146         if (!claim_shared_memory(alloc_size))
 147                 return NULL;
 148
 149         p = kvzalloc_node(alloc_size, GFP_KERNEL | __GFP_NOMEMALLOC, node);
 150         if (p)
 151                 return p;
 152
 153         free_shared_memory(alloc_size);
 154
 155         return NULL;
 156 }
 157
 158 static void dm_kvfree(void *ptr, size_t alloc_size)
 159 {
 160         if (!ptr)
 161                 return;
 162
 163         free_shared_memory(alloc_size);
 164
 165         kvfree(ptr);
 166 }
 167
 168 static void dm_stat_free(struct rcu_head *head)
 169 {
 170         int cpu;
 171         struct dm_stat *s = container_of(head, struct dm_stat, rcu_head);
 172
 173         kfree(s->histogram_boundaries);
 174         kfree(s->program_id);
 175         kfree(s->aux_data);
 176         for_each_possible_cpu(cpu) {
 177                 dm_kvfree(s->stat_percpu[cpu][0].histogram, s->histogram_alloc_size);
 178                 dm_kvfree(s->stat_percpu[cpu], s->percpu_alloc_size);
 179         }
 180         dm_kvfree(s->stat_shared[0].tmp.histogram, s->histogram_alloc_size);
 181         dm_kvfree(s, s->shared_alloc_size);
 182 }
 183
 184 static int dm_stat_in_flight(struct dm_stat_shared *shared)
 185 {
 186         return atomic_read(&shared->in_flight[READ]) +
 187                atomic_read(&shared->in_flight[WRITE]);
 188 }
 189
 190 void dm_stats_init(struct dm_stats *stats)
 191 {
 192         int cpu;
 193         struct dm_stats_last_position *last;
 194
 195         mutex_init(&stats->mutex);
 196         INIT_LIST_HEAD(&stats->list);
 197         stats->last = alloc_percpu(struct dm_stats_last_position);
 198         for_each_possible_cpu(cpu) {
 199                 last = per_cpu_ptr(stats->last, cpu);
 200                 last->last_sector = (sector_t)ULLONG_MAX;
 201                 last->last_rw = UINT_MAX;
 202         }
 203 }
 204
 205 void dm_stats_cleanup(struct dm_stats *stats)
 206 {
 207         size_t ni;
 208         struct dm_stat *s;
 209         struct dm_stat_shared *shared;
 210
 211         while (!list_empty(&stats->list)) {
 212                 s = container_of(stats->list.next, struct dm_stat, list_entry);
 213                 list_del(&s->list_entry);
 214                 for (ni = 0; ni < s->n_entries; ni++) {
 215                         shared = &s->stat_shared[ni];
 216                         if (WARN_ON(dm_stat_in_flight(shared))) {
 217                                 DMCRIT("leaked in-flight counter at index %lu "
 218                                        "(start %llu, end %llu, step %llu): reads %d, writes %d",
 219                                        (unsigned long)ni,
 220                                        (unsigned long long)s->start,
 221                                        (unsigned long long)s->end,
 222                                        (unsigned long long)s->step,
 223                                        atomic_read(&shared->in_flight[READ]),
 224                                        atomic_read(&shared->in_flight[WRITE]));
 225                         }
 226                 }
 227                 dm_stat_free(&s->rcu_head);
 228         }
 229         free_percpu(stats->last);
 230 }
 231
 232 static int dm_stats_create(struct dm_stats *stats, sector_t start, sector_t end,
 233                            sector_t step, unsigned stat_flags,
 234                            unsigned n_histogram_entries,
 235                            unsigned long long *histogram_boundaries,
 236                            const char *program_id, const char *aux_data,
 237                            void (*suspend_callback)(struct mapped_device *),
 238                            void (*resume_callback)(struct mapped_device *),
 239                            struct mapped_device *md)
 240 {
 241         struct list_head *l;
 242         struct dm_stat *s, *tmp_s;
 243         sector_t n_entries;
 244         size_t ni;
 245         size_t shared_alloc_size;
 246         size_t percpu_alloc_size;
 247         size_t histogram_alloc_size;
 248         struct dm_stat_percpu *p;
 249         int cpu;
 250         int ret_id;
 251         int r;
 252
 253         if (end < start || !step)
 254                 return -EINVAL;
 255
 256         n_entries = end - start;
 257         if (dm_sector_div64(n_entries, step))
 258                 n_entries++;
 259
 260         if (n_entries != (size_t)n_entries || !(size_t)(n_entries + 1))
 261                 return -EOVERFLOW;
 262
 263         shared_alloc_size = sizeof(struct dm_stat) + (size_t)n_entries * sizeof(struct dm_stat_shared);
 264         if ((shared_alloc_size - sizeof(struct dm_stat)) / sizeof(struct dm_stat_shared) != n_entries)
 265                 return -EOVERFLOW;
 266
 267         percpu_alloc_size = (size_t)n_entries * sizeof(struct dm_stat_percpu);
 268         if (percpu_alloc_size / sizeof(struct dm_stat_percpu) != n_entries)
 269                 return -EOVERFLOW;
 270
 271         histogram_alloc_size = (n_histogram_entries + 1) * (size_t)n_entries * sizeof(unsigned long long);
 272         if (histogram_alloc_size / (n_histogram_entries + 1) != (size_t)n_entries * sizeof(unsigned long long))
 273                 return -EOVERFLOW;
 274
 275         if (!check_shared_memory(shared_alloc_size + histogram_alloc_size +
 276                                  num_possible_cpus() * (percpu_alloc_size + histogram_alloc_size)))
 277                 return -ENOMEM;
 278
 279         s = dm_kvzalloc(shared_alloc_size, NUMA_NO_NODE);
 280         if (!s)
 281                 return -ENOMEM;
 282
 283         s->stat_flags = stat_flags;
 284         s->n_entries = n_entries;
 285         s->start = start;
 286         s->end = end;
 287         s->step = step;
 288         s->shared_alloc_size = shared_alloc_size;
 289         s->percpu_alloc_size = percpu_alloc_size;
 290         s->histogram_alloc_size = histogram_alloc_size;
 291
 292         s->n_histogram_entries = n_histogram_entries;
 293         s->histogram_boundaries = kmemdup(histogram_boundaries,
 294                                           s->n_histogram_entries * sizeof(unsigned long long), GFP_KERNEL);
 295         if (!s->histogram_boundaries) {
 296                 r = -ENOMEM;
 297                 goto out;
 298         }
 299
 300         s->program_id = kstrdup(program_id, GFP_KERNEL);
 301         if (!s->program_id) {
 302                 r = -ENOMEM;
 303                 goto out;
 304         }
 305         s->aux_data = kstrdup(aux_data, GFP_KERNEL);
 306         if (!s->aux_data) {
 307                 r = -ENOMEM;
 308                 goto out;
 309         }
 310
 311         for (ni = 0; ni < n_entries; ni++) {
 312                 atomic_set(&s->stat_shared[ni].in_flight[READ], 0);
 313                 atomic_set(&s->stat_shared[ni].in_flight[WRITE], 0);
 314         }
 315
 316         if (s->n_histogram_entries) {
 317                 unsigned long long *hi;
 318                 hi = dm_kvzalloc(s->histogram_alloc_size, NUMA_NO_NODE);
 319                 if (!hi) {
 320                         r = -ENOMEM;
 321                         goto out;
 322                 }
 323                 for (ni = 0; ni < n_entries; ni++) {
 324                         s->stat_shared[ni].tmp.histogram = hi;
 325                         hi += s->n_histogram_entries + 1;
 326                 }
 327         }
 328
 329         for_each_possible_cpu(cpu) {
 330                 p = dm_kvzalloc(percpu_alloc_size, cpu_to_node(cpu));
 331                 if (!p) {
 332                         r = -ENOMEM;
 333                         goto out;
 334                 }
 335                 s->stat_percpu[cpu] = p;
 336                 if (s->n_histogram_entries) {
 337                         unsigned long long *hi;
 338                         hi = dm_kvzalloc(s->histogram_alloc_size, cpu_to_node(cpu));
 339                         if (!hi) {
 340                                 r = -ENOMEM;
 341                                 goto out;
 342                         }
 343                         for (ni = 0; ni < n_entries; ni++) {
 344                                 p[ni].histogram = hi;
 345                                 hi += s->n_histogram_entries + 1;
 346                         }
 347                 }
 348         }
 349
 350         /*
 351          * Suspend/resume to make sure there is no i/o in flight,
 352          * so that newly created statistics will be exact.
 353          *
 354          * (note: we couldn't suspend earlier because we must not
 355          * allocate memory while suspended)
 356          */
 357         suspend_callback(md);
 358
 359         mutex_lock(&stats->mutex);
 360         s->id = 0;
 361         list_for_each(l, &stats->list) {
 362                 tmp_s = container_of(l, struct dm_stat, list_entry);
 363                 if (WARN_ON(tmp_s->id < s->id)) {
 364                         r = -EINVAL;
 365                         goto out_unlock_resume;
 366                 }
 367                 if (tmp_s->id > s->id)
 368                         break;
 369                 if (unlikely(s->id == INT_MAX)) {
 370                         r = -ENFILE;
 371                         goto out_unlock_resume;
 372                 }
 373                 s->id++;
 374         }
 375         ret_id = s->id;
 376         list_add_tail_rcu(&s->list_entry, l);
 377         mutex_unlock(&stats->mutex);
 378
 379         resume_callback(md);
 380
 381         return ret_id;
 382
 383 out_unlock_resume:
 384         mutex_unlock(&stats->mutex);
 385         resume_callback(md);
 386 out:
 387         dm_stat_free(&s->rcu_head);
 388         return r;
 389 }
 390
 391 static struct dm_stat *__dm_stats_find(struct dm_stats *stats, int id)
 392 {
 393         struct dm_stat *s;
 394
 395         list_for_each_entry(s, &stats->list, list_entry) {
 396                 if (s->id > id)
 397                         break;
 398                 if (s->id == id)
 399                         return s;
 400         }
 401
 402         return NULL;
 403 }
 404
 405 static int dm_stats_delete(struct dm_stats *stats, int id)
 406 {
 407         struct dm_stat *s;
 408         int cpu;
 409
 410         mutex_lock(&stats->mutex);
 411
 412         s = __dm_stats_find(stats, id);
 413         if (!s) {
 414                 mutex_unlock(&stats->mutex);
 415                 return -ENOENT;
 416         }
 417
 418         list_del_rcu(&s->list_entry);
 419         mutex_unlock(&stats->mutex);
 420
 421         /*
 422          * vfree can't be called from RCU callback
 423          */
 424         for_each_possible_cpu(cpu)
 425                 if (is_vmalloc_addr(s->stat_percpu) ||
 426                     is_vmalloc_addr(s->stat_percpu[cpu][0].histogram))
 427                         goto do_sync_free;
 428         if (is_vmalloc_addr(s) ||
 429             is_vmalloc_addr(s->stat_shared[0].tmp.histogram)) {
 430 do_sync_free:
 431                 synchronize_rcu_expedited();
 432                 dm_stat_free(&s->rcu_head);
 433         } else {
 434                 ACCESS_ONCE(dm_stat_need_rcu_barrier) = 1;
 435                 call_rcu(&s->rcu_head, dm_stat_free);
 436         }
 437         return 0;
 438 }
 439
 440 static int dm_stats_list(struct dm_stats *stats, const char *program,
 441                          char *result, unsigned maxlen)
 442 {
 443         struct dm_stat *s;
 444         sector_t len;
 445         unsigned sz = 0;
 446
 447         /*
 448          * Output format:
 449          *   <region_id>: <start_sector>+<length> <step> <program_id> <aux_data>
 450          */
 451
 452         mutex_lock(&stats->mutex);
 453         list_for_each_entry(s, &stats->list, list_entry) {
 454                 if (!program || !strcmp(program, s->program_id)) {
 455                         len = s->end - s->start;
 456                         DMEMIT("%d: %llu+%llu %llu %s %s", s->id,
 457                                 (unsigned long long)s->start,
 458                                 (unsigned long long)len,
 459                                 (unsigned long long)s->step,
 460                                 s->program_id,
 461                                 s->aux_data);
 462                         if (s->stat_flags & STAT_PRECISE_TIMESTAMPS)
 463                                 DMEMIT(" precise_timestamps");
 464                         if (s->n_histogram_entries) {
 465                                 unsigned i;
 466                                 DMEMIT(" histogram:");
 467                                 for (i = 0; i < s->n_histogram_entries; i++) {
 468                                         if (i)
 469                                                 DMEMIT(",");
 470                                         DMEMIT("%llu", s->histogram_boundaries[i]);
 471                                 }
 472                         }
 473                         DMEMIT("\n");
 474                 }
 475         }
 476         mutex_unlock(&stats->mutex);
 477
 478         return 1;
 479 }
 480
 481 static void dm_stat_round(struct dm_stat *s, struct dm_stat_shared *shared,
 482                           struct dm_stat_percpu *p)
 483 {
 484         /*
 485          * This is racy, but so is part_round_stats_single.
 486          */
 487         unsigned long long now, difference;
 488         unsigned in_flight_read, in_flight_write;
 489
 490         if (likely(!(s->stat_flags & STAT_PRECISE_TIMESTAMPS)))
 491                 now = jiffies;
 492         else
 493                 now = ktime_to_ns(ktime_get());
 494
 495         difference = now - shared->stamp;
 496         if (!difference)
 497                 return;
 498
 499         in_flight_read = (unsigned)atomic_read(&shared->in_flight[READ]);
 500         in_flight_write = (unsigned)atomic_read(&shared->in_flight[WRITE]);
 501         if (in_flight_read)
 502                 p->io_ticks[READ] += difference;
 503         if (in_flight_write)
 504                 p->io_ticks[WRITE] += difference;
 505         if (in_flight_read + in_flight_write) {
 506                 p->io_ticks_total += difference;
 507                 p->time_in_queue += (in_flight_read + in_flight_write) * difference;
 508         }
 509         shared->stamp = now;
 510 }
 511
 512 static void dm_stat_for_entry(struct dm_stat *s, size_t entry,
 513                               int idx, sector_t len,
 514                               struct dm_stats_aux *stats_aux, bool end,
 515                               unsigned long duration_jiffies)
 516 {
 517         struct dm_stat_shared *shared = &s->stat_shared[entry];
 518         struct dm_stat_percpu *p;
 519
 520         /*
 521          * For strict correctness we should use local_irq_save/restore
 522          * instead of preempt_disable/enable.
 523          *
 524          * preempt_disable/enable is racy if the driver finishes bios
 525          * from non-interrupt context as well as from interrupt context
 526          * or from more different interrupts.
 527          *
 528          * On 64-bit architectures the race only results in not counting some
 529          * events, so it is acceptable.  On 32-bit architectures the race could
 530          * cause the counter going off by 2^32, so we need to do proper locking
 531          * there.
 532          *
 533          * part_stat_lock()/part_stat_unlock() have this race too.
 534          */
 535 #if BITS_PER_LONG == 32
 536         unsigned long flags;
 537         local_irq_save(flags);
 538 #else
 539         preempt_disable();
 540 #endif
 541         p = &s->stat_percpu[smp_processor_id()][entry];
 542
 543         if (!end) {
 544                 dm_stat_round(s, shared, p);
 545                 atomic_inc(&shared->in_flight[idx]);
 546         } else {
 547                 unsigned long long duration;
 548                 dm_stat_round(s, shared, p);
 549                 atomic_dec(&shared->in_flight[idx]);
 550                 p->sectors[idx] += len;
 551                 p->ios[idx] += 1;
 552                 p->merges[idx] += stats_aux->merged;
 553                 if (!(s->stat_flags & STAT_PRECISE_TIMESTAMPS)) {
 554                         p->ticks[idx] += duration_jiffies;
 555                         duration = jiffies_to_msecs(duration_jiffies);
 556                 } else {
 557                         p->ticks[idx] += stats_aux->duration_ns;
 558                         duration = stats_aux->duration_ns;
 559                 }
 560                 if (s->n_histogram_entries) {
 561                         unsigned lo = 0, hi = s->n_histogram_entries + 1;
 562                         while (lo + 1 < hi) {
 563                                 unsigned mid = (lo + hi) / 2;
 564                                 if (s->histogram_boundaries[mid - 1] > duration) {
 565                                         hi = mid;
 566                                 } else {
 567                                         lo = mid;
 568                                 }
 569
 570                         }
 571                         p->histogram[lo]++;
 572                 }
 573         }
 574
 575 #if BITS_PER_LONG == 32
 576         local_irq_restore(flags);
 577 #else
 578         preempt_enable();
 579 #endif
 580 }
 581
 582 static void __dm_stat_bio(struct dm_stat *s, int bi_rw,
 583                           sector_t bi_sector, sector_t end_sector,
 584                           bool end, unsigned long duration_jiffies,
 585                           struct dm_stats_aux *stats_aux)
 586 {
 587         sector_t rel_sector, offset, todo, fragment_len;
 588         size_t entry;
 589
 590         if (end_sector <= s->start || bi_sector >= s->end)
 591                 return;
 592         if (unlikely(bi_sector < s->start)) {
 593                 rel_sector = 0;
 594                 todo = end_sector - s->start;
 595         } else {
 596                 rel_sector = bi_sector - s->start;
 597                 todo = end_sector - bi_sector;
 598         }
 599         if (unlikely(end_sector > s->end))
 600                 todo -= (end_sector - s->end);
 601
 602         offset = dm_sector_div64(rel_sector, s->step);
 603         entry = rel_sector;
 604         do {
 605                 if (WARN_ON_ONCE(entry >= s->n_entries)) {
 606                         DMCRIT("Invalid area access in region id %d", s->id);
 607                         return;
 608                 }
 609                 fragment_len = todo;
 610                 if (fragment_len > s->step - offset)
 611                         fragment_len = s->step - offset;
 612                 dm_stat_for_entry(s, entry, bi_rw, fragment_len,
 613                                   stats_aux, end, duration_jiffies);
 614                 todo -= fragment_len;
 615                 entry++;
 616                 offset = 0;
 617         } while (unlikely(todo != 0));
 618 }
 619
 620 void dm_stats_account_io(struct dm_stats *stats, unsigned long bi_rw,
 621                          sector_t bi_sector, unsigned bi_sectors, bool end,
 622                          unsigned long duration_jiffies,
 623                          struct dm_stats_aux *stats_aux)
 624 {
 625         struct dm_stat *s;
 626         sector_t end_sector;
 627         struct dm_stats_last_position *last;
 628         bool got_precise_time;
 629
 630         if (unlikely(!bi_sectors))
 631                 return;
 632
 633         end_sector = bi_sector + bi_sectors;
 634
 635         if (!end) {
 636                 /*
 637                  * A race condition can at worst result in the merged flag being
 638                  * misrepresented, so we don't have to disable preemption here.
 639                  */
 640                 last = raw_cpu_ptr(stats->last);
 641                 stats_aux->merged =
 642                         (bi_sector == (ACCESS_ONCE(last->last_sector) &&
 643                                        ((bi_rw == WRITE) ==
 644                                         (ACCESS_ONCE(last->last_rw) == WRITE))
 645                                        ));
 646                 ACCESS_ONCE(last->last_sector) = end_sector;
 647                 ACCESS_ONCE(last->last_rw) = bi_rw;
 648         }
 649
 650         rcu_read_lock();
 651
 652         got_precise_time = false;
 653         list_for_each_entry_rcu(s, &stats->list, list_entry) {
 654                 if (s->stat_flags & STAT_PRECISE_TIMESTAMPS && !got_precise_time) {
 655                         if (!end)
 656                                 stats_aux->duration_ns = ktime_to_ns(ktime_get());
 657                         else
 658                                 stats_aux->duration_ns = ktime_to_ns(ktime_get()) - stats_aux->duration_ns;
 659                         got_precise_time = true;
 660                 }
 661                 __dm_stat_bio(s, bi_rw, bi_sector, end_sector, end, duration_jiffies, stats_aux);
 662         }
 663
 664         rcu_read_unlock();
 665 }
 666
 667 static void __dm_stat_init_temporary_percpu_totals(struct dm_stat_shared *shared,
 668                                                    struct dm_stat *s, size_t x)
 669 {
 670         int cpu;
 671         struct dm_stat_percpu *p;
 672
 673         local_irq_disable();
 674         p = &s->stat_percpu[smp_processor_id()][x];
 675         dm_stat_round(s, shared, p);
 676         local_irq_enable();
 677
 678         shared->tmp.sectors[READ] = 0;
 679         shared->tmp.sectors[WRITE] = 0;
 680         shared->tmp.ios[READ] = 0;
 681         shared->tmp.ios[WRITE] = 0;
 682         shared->tmp.merges[READ] = 0;
 683         shared->tmp.merges[WRITE] = 0;
 684         shared->tmp.ticks[READ] = 0;
 685         shared->tmp.ticks[WRITE] = 0;
 686         shared->tmp.io_ticks[READ] = 0;
 687         shared->tmp.io_ticks[WRITE] = 0;
 688         shared->tmp.io_ticks_total = 0;
 689         shared->tmp.time_in_queue = 0;
 690
 691         if (s->n_histogram_entries)
 692                 memset(shared->tmp.histogram, 0, (s->n_histogram_entries + 1) * sizeof(unsigned long long));
 693
 694         for_each_possible_cpu(cpu) {
 695                 p = &s->stat_percpu[cpu][x];
 696                 shared->tmp.sectors[READ] += ACCESS_ONCE(p->sectors[READ]);
 697                 shared->tmp.sectors[WRITE] += ACCESS_ONCE(p->sectors[WRITE]);
 698                 shared->tmp.ios[READ] += ACCESS_ONCE(p->ios[READ]);
 699                 shared->tmp.ios[WRITE] += ACCESS_ONCE(p->ios[WRITE]);
 700                 shared->tmp.merges[READ] += ACCESS_ONCE(p->merges[READ]);
 701                 shared->tmp.merges[WRITE] += ACCESS_ONCE(p->merges[WRITE]);
 702                 shared->tmp.ticks[READ] += ACCESS_ONCE(p->ticks[READ]);
 703                 shared->tmp.ticks[WRITE] += ACCESS_ONCE(p->ticks[WRITE]);
 704                 shared->tmp.io_ticks[READ] += ACCESS_ONCE(p->io_ticks[READ]);
 705                 shared->tmp.io_ticks[WRITE] += ACCESS_ONCE(p->io_ticks[WRITE]);
 706                 shared->tmp.io_ticks_total += ACCESS_ONCE(p->io_ticks_total);
 707                 shared->tmp.time_in_queue += ACCESS_ONCE(p->time_in_queue);
 708                 if (s->n_histogram_entries) {
 709                         unsigned i;
 710                         for (i = 0; i < s->n_histogram_entries + 1; i++)
 711                                 shared->tmp.histogram[i] += ACCESS_ONCE(p->histogram[i]);
 712                 }
 713         }
 714 }
 715
 716 static void __dm_stat_clear(struct dm_stat *s, size_t idx_start, size_t idx_end,
 717                             bool init_tmp_percpu_totals)
 718 {
 719         size_t x;
 720         struct dm_stat_shared *shared;
 721         struct dm_stat_percpu *p;
 722
 723         for (x = idx_start; x < idx_end; x++) {
 724                 shared = &s->stat_shared[x];
 725                 if (init_tmp_percpu_totals)
 726                         __dm_stat_init_temporary_percpu_totals(shared, s, x);
 727                 local_irq_disable();
 728                 p = &s->stat_percpu[smp_processor_id()][x];
 729                 p->sectors[READ] -= shared->tmp.sectors[READ];
 730                 p->sectors[WRITE] -= shared->tmp.sectors[WRITE];
 731                 p->ios[READ] -= shared->tmp.ios[READ];
 732                 p->ios[WRITE] -= shared->tmp.ios[WRITE];
 733                 p->merges[READ] -= shared->tmp.merges[READ];
 734                 p->merges[WRITE] -= shared->tmp.merges[WRITE];
 735                 p->ticks[READ] -= shared->tmp.ticks[READ];
 736                 p->ticks[WRITE] -= shared->tmp.ticks[WRITE];
 737                 p->io_ticks[READ] -= shared->tmp.io_ticks[READ];
 738                 p->io_ticks[WRITE] -= shared->tmp.io_ticks[WRITE];
 739                 p->io_ticks_total -= shared->tmp.io_ticks_total;
 740                 p->time_in_queue -= shared->tmp.time_in_queue;
 741                 local_irq_enable();
 742                 if (s->n_histogram_entries) {
 743                         unsigned i;
 744                         for (i = 0; i < s->n_histogram_entries + 1; i++) {
 745                                 local_irq_disable();
 746                                 p = &s->stat_percpu[smp_processor_id()][x];
 747                                 p->histogram[i] -= shared->tmp.histogram[i];
 748                                 local_irq_enable();
 749                         }
 750                 }
 751         }
 752 }
 753
 754 static int dm_stats_clear(struct dm_stats *stats, int id)
 755 {
 756         struct dm_stat *s;
 757
 758         mutex_lock(&stats->mutex);
 759
 760         s = __dm_stats_find(stats, id);
 761         if (!s) {
 762                 mutex_unlock(&stats->mutex);
 763                 return -ENOENT;
 764         }
 765
 766         __dm_stat_clear(s, 0, s->n_entries, true);
 767
 768         mutex_unlock(&stats->mutex);
 769
 770         return 1;
 771 }
 772
 773 /*
 774  * This is like jiffies_to_msec, but works for 64-bit values.
 775  */
 776 static unsigned long long dm_jiffies_to_msec64(struct dm_stat *s, unsigned long long j)
 777 {
 778         unsigned long long result;
 779         unsigned mult;
 780
 781         if (s->stat_flags & STAT_PRECISE_TIMESTAMPS)
 782                 return j;
 783
 784         result = 0;
 785         if (j)
 786                 result = jiffies_to_msecs(j & 0x3fffff);
 787         if (j >= 1 << 22) {
 788                 mult = jiffies_to_msecs(1 << 22);
 789                 result += (unsigned long long)mult * (unsigned long long)jiffies_to_msecs((j >> 22) & 0x3fffff);
 790         }
 791         if (j >= 1ULL << 44)
 792                 result += (unsigned long long)mult * (unsigned long long)mult * (unsigned long long)jiffies_to_msecs(j >> 44);
 793
 794         return result;
 795 }
 796
 797 static int dm_stats_print(struct dm_stats *stats, int id,
 798                           size_t idx_start, size_t idx_len,
 799                           bool clear, char *result, unsigned maxlen)
 800 {
 801         unsigned sz = 0;
 802         struct dm_stat *s;
 803         size_t x;
 804         sector_t start, end, step;
 805         size_t idx_end;
 806         struct dm_stat_shared *shared;
 807
 808         /*
 809          * Output format:
 810          *   <start_sector>+<length> counters
 811          */
 812
 813         mutex_lock(&stats->mutex);
 814
 815         s = __dm_stats_find(stats, id);
 816         if (!s) {
 817                 mutex_unlock(&stats->mutex);
 818                 return -ENOENT;
 819         }
 820
 821         idx_end = idx_start + idx_len;
 822         if (idx_end < idx_start ||
 823             idx_end > s->n_entries)
 824                 idx_end = s->n_entries;
 825
 826         if (idx_start > idx_end)
 827                 idx_start = idx_end;
 828
 829         step = s->step;
 830         start = s->start + (step * idx_start);
 831
 832         for (x = idx_start; x < idx_end; x++, start = end) {
 833                 shared = &s->stat_shared[x];
 834                 end = start + step;
 835                 if (unlikely(end > s->end))
 836                         end = s->end;
 837
 838                 __dm_stat_init_temporary_percpu_totals(shared, s, x);
 839
 840                 DMEMIT("%llu+%llu %llu %llu %llu %llu %llu %llu %llu %llu %d %llu %llu %llu %llu",
 841                        (unsigned long long)start,
 842                        (unsigned long long)step,
 843                        shared->tmp.ios[READ],
 844                        shared->tmp.merges[READ],
 845                        shared->tmp.sectors[READ],
 846                        dm_jiffies_to_msec64(s, shared->tmp.ticks[READ]),
 847                        shared->tmp.ios[WRITE],
 848                        shared->tmp.merges[WRITE],
 849                        shared->tmp.sectors[WRITE],
 850                        dm_jiffies_to_msec64(s, shared->tmp.ticks[WRITE]),
 851                        dm_stat_in_flight(shared),
 852                        dm_jiffies_to_msec64(s, shared->tmp.io_ticks_total),
 853                        dm_jiffies_to_msec64(s, shared->tmp.time_in_queue),
 854                        dm_jiffies_to_msec64(s, shared->tmp.io_ticks[READ]),
 855                        dm_jiffies_to_msec64(s, shared->tmp.io_ticks[WRITE]));
 856                 if (s->n_histogram_entries) {
 857                         unsigned i;
 858                         for (i = 0; i < s->n_histogram_entries + 1; i++) {
 859                                 DMEMIT("%s%llu", !i ? " " : ":", shared->tmp.histogram[i]);
 860                         }
 861                 }
 862                 DMEMIT("\n");
 863
 864                 if (unlikely(sz + 1 >= maxlen))
 865                         goto buffer_overflow;
 866         }
 867
 868         if (clear)
 869                 __dm_stat_clear(s, idx_start, idx_end, false);
 870
 871 buffer_overflow:
 872         mutex_unlock(&stats->mutex);
 873
 874         return 1;
 875 }
 876
 877 static int dm_stats_set_aux(struct dm_stats *stats, int id, const char *aux_data)
 878 {
 879         struct dm_stat *s;
 880         const char *new_aux_data;
 881
 882         mutex_lock(&stats->mutex);
 883
 884         s = __dm_stats_find(stats, id);
 885         if (!s) {
 886                 mutex_unlock(&stats->mutex);
 887                 return -ENOENT;
 888         }
 889
 890         new_aux_data = kstrdup(aux_data, GFP_KERNEL);
 891         if (!new_aux_data) {
 892                 mutex_unlock(&stats->mutex);
 893                 return -ENOMEM;
 894         }
 895
 896         kfree(s->aux_data);
 897         s->aux_data = new_aux_data;
 898
 899         mutex_unlock(&stats->mutex);
 900
 901         return 0;
 902 }
 903
 904 static int parse_histogram(const char *h, unsigned *n_histogram_entries,
 905                            unsigned long long **histogram_boundaries)
 906 {
 907         const char *q;
 908         unsigned n;
 909         unsigned long long last;
 910
 911         *n_histogram_entries = 1;
 912         for (q = h; *q; q++)
 913                 if (*q == ',')
 914                         (*n_histogram_entries)++;
 915
 916         *histogram_boundaries = kmalloc(*n_histogram_entries * sizeof(unsigned long long), GFP_KERNEL);
 917         if (!*histogram_boundaries)
 918                 return -ENOMEM;
 919
 920         n = 0;
 921         last = 0;
 922         while (1) {
 923                 unsigned long long hi;
 924                 int s;
 925                 char ch;
 926                 s = sscanf(h, "%llu%c", &hi, &ch);
 927                 if (!s || (s == 2 && ch != ','))
 928                         return -EINVAL;
 929                 if (hi <= last)
 930                         return -EINVAL;
 931                 last = hi;
 932                 (*histogram_boundaries)[n] = hi;
 933                 if (s == 1)
 934                         return 0;
 935                 h = strchr(h, ',') + 1;
 936                 n++;
 937         }
 938 }
 939
 940 static int message_stats_create(struct mapped_device *md,
 941                                 unsigned argc, char **argv,
 942                                 char *result, unsigned maxlen)
 943 {
 944         int r;
 945         int id;
 946         char dummy;
 947         unsigned long long start, end, len, step;
 948         unsigned divisor;
 949         const char *program_id, *aux_data;
 950         unsigned stat_flags = 0;
 951
 952         unsigned n_histogram_entries = 0;
 953         unsigned long long *histogram_boundaries = NULL;
 954
 955         struct dm_arg_set as, as_backup;
 956         const char *a;
 957         unsigned feature_args;
 958
 959         /*
 960          * Input format:
 961          *   <range> <step> [<extra_parameters> <parameters>] [<program_id> [<aux_data>]]
 962          */
 963
 964         if (argc < 3)
 965                 goto ret_einval;
 966
 967         as.argc = argc;
 968         as.argv = argv;
 969         dm_consume_args(&as, 1);
 970
 971         a = dm_shift_arg(&as);
 972         if (!strcmp(a, "-")) {
 973                 start = 0;
 974                 len = dm_get_size(md);
 975                 if (!len)
 976                         len = 1;
 977         } else if (sscanf(a, "%llu+%llu%c", &start, &len, &dummy) != 2 ||
 978                    start != (sector_t)start || len != (sector_t)len)
 979                 goto ret_einval;
 980
 981         end = start + len;
 982         if (start >= end)
 983                 goto ret_einval;
 984
 985         a = dm_shift_arg(&as);
 986         if (sscanf(a, "/%u%c", &divisor, &dummy) == 1) {
 987                 if (!divisor)
 988                         return -EINVAL;
 989                 step = end - start;
 990                 if (do_div(step, divisor))
 991                         step++;
 992                 if (!step)
 993                         step = 1;
 994         } else if (sscanf(a, "%llu%c", &step, &dummy) != 1 ||
 995                    step != (sector_t)step || !step)
 996                 goto ret_einval;
 997
 998         as_backup = as;
 999         a = dm_shift_arg(&as);
1000         if (a && sscanf(a, "%u%c", &feature_args, &dummy) == 1) {
1001                 while (feature_args--) {
1002                         a = dm_shift_arg(&as);
1003                         if (!a)
1004                                 goto ret_einval;
1005                         if (!strcasecmp(a, "precise_timestamps"))
1006                                 stat_flags |= STAT_PRECISE_TIMESTAMPS;
1007                         else if (!strncasecmp(a, "histogram:", 10)) {
1008                                 if (n_histogram_entries)
1009                                         goto ret_einval;
1010                                 if ((r = parse_histogram(a + 10, &n_histogram_entries, &histogram_boundaries)))
1011                                         goto ret;
1012                         } else
1013                                 goto ret_einval;
1014                 }
1015         } else {
1016                 as = as_backup;
1017         }
1018
1019         program_id = "-";
1020         aux_data = "-";
1021
1022         a = dm_shift_arg(&as);
1023         if (a)
1024                 program_id = a;
1025
1026         a = dm_shift_arg(&as);
1027         if (a)
1028                 aux_data = a;
1029
1030         if (as.argc)
1031                 goto ret_einval;
1032
1033         /*
1034          * If a buffer overflow happens after we created the region,
1035          * it's too late (the userspace would retry with a larger
1036          * buffer, but the region id that caused the overflow is already
1037          * leaked).  So we must detect buffer overflow in advance.
1038          */
1039         snprintf(result, maxlen, "%d", INT_MAX);
1040         if (dm_message_test_buffer_overflow(result, maxlen)) {
1041                 r = 1;
1042                 goto ret;
1043         }
1044
1045         id = dm_stats_create(dm_get_stats(md), start, end, step, stat_flags,
1046                              n_histogram_entries, histogram_boundaries, program_id, aux_data,
1047                              dm_internal_suspend_fast, dm_internal_resume_fast, md);
1048         if (id < 0) {
1049                 r = id;
1050                 goto ret;
1051         }
1052
1053         snprintf(result, maxlen, "%d", id);
1054
1055         r = 1;
1056         goto ret;
1057
1058 ret_einval:
1059         r = -EINVAL;
1060 ret:
1061         kfree(histogram_boundaries);
1062         return r;
1063 }
1064
1065 static int message_stats_delete(struct mapped_device *md,
1066                                 unsigned argc, char **argv)
1067 {
1068         int id;
1069         char dummy;
1070
1071         if (argc != 2)
1072                 return -EINVAL;
1073
1074         if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
1075                 return -EINVAL;
1076
1077         return dm_stats_delete(dm_get_stats(md), id);
1078 }
1079
1080 static int message_stats_clear(struct mapped_device *md,
1081                                unsigned argc, char **argv)
1082 {
1083         int id;
1084         char dummy;
1085
1086         if (argc != 2)
1087                 return -EINVAL;
1088
1089         if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
1090                 return -EINVAL;
1091
1092         return dm_stats_clear(dm_get_stats(md), id);
1093 }
1094
1095 static int message_stats_list(struct mapped_device *md,
1096                               unsigned argc, char **argv,
1097                               char *result, unsigned maxlen)
1098 {
1099         int r;
1100         const char *program = NULL;
1101
1102         if (argc < 1 || argc > 2)
1103                 return -EINVAL;
1104
1105         if (argc > 1) {
1106                 program = kstrdup(argv[1], GFP_KERNEL);
1107                 if (!program)
1108                         return -ENOMEM;
1109         }
1110
1111         r = dm_stats_list(dm_get_stats(md), program, result, maxlen);
1112
1113         kfree(program);
1114
1115         return r;
1116 }
1117
1118 static int message_stats_print(struct mapped_device *md,
1119                                unsigned argc, char **argv, bool clear,
1120                                char *result, unsigned maxlen)
1121 {
1122         int id;
1123         char dummy;
1124         unsigned long idx_start = 0, idx_len = ULONG_MAX;
1125
1126         if (argc != 2 && argc != 4)
1127                 return -EINVAL;
1128
1129         if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
1130                 return -EINVAL;
1131
1132         if (argc > 3) {
1133                 if (strcmp(argv[2], "-") &&
1134                     sscanf(argv[2], "%lu%c", &idx_start, &dummy) != 1)
1135                         return -EINVAL;
1136                 if (strcmp(argv[3], "-") &&
1137                     sscanf(argv[3], "%lu%c", &idx_len, &dummy) != 1)
1138                         return -EINVAL;
1139         }
1140
1141         return dm_stats_print(dm_get_stats(md), id, idx_start, idx_len, clear,
1142                               result, maxlen);
1143 }
1144
1145 static int message_stats_set_aux(struct mapped_device *md,
1146                                  unsigned argc, char **argv)
1147 {
1148         int id;
1149         char dummy;
1150
1151         if (argc != 3)
1152                 return -EINVAL;
1153
1154         if (sscanf(argv[1], "%d%c", &id, &dummy) != 1 || id < 0)
1155                 return -EINVAL;
1156
1157         return dm_stats_set_aux(dm_get_stats(md), id, argv[2]);
1158 }
1159
1160 int dm_stats_message(struct mapped_device *md, unsigned argc, char **argv,
1161                      char *result, unsigned maxlen)
1162 {
1163         int r;
1164
1165         /* All messages here must start with '@' */
1166         if (!strcasecmp(argv[0], "@stats_create"))
1167                 r = message_stats_create(md, argc, argv, result, maxlen);
1168         else if (!strcasecmp(argv[0], "@stats_delete"))
1169                 r = message_stats_delete(md, argc, argv);
1170         else if (!strcasecmp(argv[0], "@stats_clear"))
1171                 r = message_stats_clear(md, argc, argv);
1172         else if (!strcasecmp(argv[0], "@stats_list"))
1173                 r = message_stats_list(md, argc, argv, result, maxlen);
1174         else if (!strcasecmp(argv[0], "@stats_print"))
1175                 r = message_stats_print(md, argc, argv, false, result, maxlen);
1176         else if (!strcasecmp(argv[0], "@stats_print_clear"))
1177                 r = message_stats_print(md, argc, argv, true, result, maxlen);
1178         else if (!strcasecmp(argv[0], "@stats_set_aux"))
1179                 r = message_stats_set_aux(md, argc, argv);
1180         else
1181                 return 2; /* this wasn't a stats message */
1182
1183         if (r == -EINVAL)
1184                 DMWARN("Invalid parameters for message %s", argv[0]);
1185
1186         return r;
1187 }
1188
1189 int __init dm_statistics_init(void)
1190 {
1191         shared_memory_amount = 0;
1192         dm_stat_need_rcu_barrier = 0;
1193         return 0;
1194 }
1195
1196 void dm_statistics_exit(void)
1197 {
1198         if (dm_stat_need_rcu_barrier)
1199                 rcu_barrier();
1200         if (WARN_ON(shared_memory_amount))
1201                 DMCRIT("shared_memory_amount leaked: %lu", shared_memory_amount);
1202 }
1203
1204 module_param_named(stats_current_allocated_bytes, shared_memory_amount, ulong, S_IRUGO);
1205 MODULE_PARM_DESC(stats_current_allocated_bytes, "Memory currently used by statistics");