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