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