drivers/md/bcache/request.c

   1 /*
   2  * Main bcache entry point - handle a read or a write request and decide what to
   3  * do with it; the make_request functions are called by the block layer.
   4  *
   5  * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
   6  * Copyright 2012 Google, Inc.
   7  */
   8
   9 #include "bcache.h"
  10 #include "btree.h"
  11 #include "debug.h"
  12 #include "request.h"
  13 #include "writeback.h"
  14
  15 #include <linux/module.h>
  16 #include <linux/hash.h>
  17 #include <linux/random.h>
  18 #include <linux/backing-dev.h>
  19
  20 #include <trace/events/bcache.h>
  21
  22 #define CUTOFF_CACHE_ADD        95
  23 #define CUTOFF_CACHE_READA      90
  24
  25 struct kmem_cache *bch_search_cache;
  26
  27 static void bch_data_insert_start(struct closure *);
  28
  29 static unsigned cache_mode(struct cached_dev *dc, struct bio *bio)
  30 {
  31         return BDEV_CACHE_MODE(&dc->sb);
  32 }
  33
  34 static bool verify(struct cached_dev *dc, struct bio *bio)
  35 {
  36         return dc->verify;
  37 }
  38
  39 static void bio_csum(struct bio *bio, struct bkey *k)
  40 {
  41         struct bio_vec bv;
  42         struct bvec_iter iter;
  43         uint64_t csum = 0;
  44
  45         bio_for_each_segment(bv, bio, iter) {
  46                 void *d = kmap(bv.bv_page) + bv.bv_offset;
  47                 csum = bch_crc64_update(csum, d, bv.bv_len);
  48                 kunmap(bv.bv_page);
  49         }
  50
  51         k->ptr[KEY_PTRS(k)] = csum & (~0ULL >> 1);
  52 }
  53
  54 /* Insert data into cache */
  55
  56 static void bch_data_insert_keys(struct closure *cl)
  57 {
  58         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
  59         atomic_t *journal_ref = NULL;
  60         struct bkey *replace_key = op->replace ? &op->replace_key : NULL;
  61         int ret;
  62
  63         /*
  64          * If we're looping, might already be waiting on
  65          * another journal write - can't wait on more than one journal write at
  66          * a time
  67          *
  68          * XXX: this looks wrong
  69          */
  70 #if 0
  71         while (atomic_read(&s->cl.remaining) & CLOSURE_WAITING)
  72                 closure_sync(&s->cl);
  73 #endif
  74
  75         if (!op->replace)
  76                 journal_ref = bch_journal(op->c, &op->insert_keys,
  77                                           op->flush_journal ? cl : NULL);
  78
  79         ret = bch_btree_insert(op->c, &op->insert_keys,
  80                                journal_ref, replace_key);
  81         if (ret == -ESRCH) {
  82                 op->replace_collision = true;
  83         } else if (ret) {
  84                 op->error               = -ENOMEM;
  85                 op->insert_data_done    = true;
  86         }
  87
  88         if (journal_ref)
  89                 atomic_dec_bug(journal_ref);
  90
  91         if (!op->insert_data_done) {
  92                 continue_at(cl, bch_data_insert_start, op->wq);
  93                 return;
  94         }
  95
  96         bch_keylist_free(&op->insert_keys);
  97         closure_return(cl);
  98 }
  99
 100 static int bch_keylist_realloc(struct keylist *l, unsigned u64s,
 101                                struct cache_set *c)
 102 {
 103         size_t oldsize = bch_keylist_nkeys(l);
 104         size_t newsize = oldsize + u64s;
 105
 106         /*
 107          * The journalling code doesn't handle the case where the keys to insert
 108          * is bigger than an empty write: If we just return -ENOMEM here,
 109          * bio_insert() and bio_invalidate() will insert the keys created so far
 110          * and finish the rest when the keylist is empty.
 111          */
 112         if (newsize * sizeof(uint64_t) > block_bytes(c) - sizeof(struct jset))
 113                 return -ENOMEM;
 114
 115         return __bch_keylist_realloc(l, u64s);
 116 }
 117
 118 static void bch_data_invalidate(struct closure *cl)
 119 {
 120         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 121         struct bio *bio = op->bio;
 122
 123         pr_debug("invalidating %i sectors from %llu",
 124                  bio_sectors(bio), (uint64_t) bio->bi_iter.bi_sector);
 125
 126         while (bio_sectors(bio)) {
 127                 unsigned sectors = min(bio_sectors(bio),
 128                                        1U << (KEY_SIZE_BITS - 1));
 129
 130                 if (bch_keylist_realloc(&op->insert_keys, 2, op->c))
 131                         goto out;
 132
 133                 bio->bi_iter.bi_sector  += sectors;
 134                 bio->bi_iter.bi_size    -= sectors << 9;
 135
 136                 bch_keylist_add(&op->insert_keys,
 137                                 &KEY(op->inode, bio->bi_iter.bi_sector, sectors));
 138         }
 139
 140         op->insert_data_done = true;
 141         bio_put(bio);
 142 out:
 143         continue_at(cl, bch_data_insert_keys, op->wq);
 144 }
 145
 146 static void bch_data_insert_error(struct closure *cl)
 147 {
 148         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 149
 150         /*
 151          * Our data write just errored, which means we've got a bunch of keys to
 152          * insert that point to data that wasn't succesfully written.
 153          *
 154          * We don't have to insert those keys but we still have to invalidate
 155          * that region of the cache - so, if we just strip off all the pointers
 156          * from the keys we'll accomplish just that.
 157          */
 158
 159         struct bkey *src = op->insert_keys.keys, *dst = op->insert_keys.keys;
 160
 161         while (src != op->insert_keys.top) {
 162                 struct bkey *n = bkey_next(src);
 163
 164                 SET_KEY_PTRS(src, 0);
 165                 memmove(dst, src, bkey_bytes(src));
 166
 167                 dst = bkey_next(dst);
 168                 src = n;
 169         }
 170
 171         op->insert_keys.top = dst;
 172
 173         bch_data_insert_keys(cl);
 174 }
 175
 176 static void bch_data_insert_endio(struct bio *bio)
 177 {
 178         struct closure *cl = bio->bi_private;
 179         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 180
 181         if (bio->bi_error) {
 182                 /* TODO: We could try to recover from this. */
 183                 if (op->writeback)
 184                         op->error = bio->bi_error;
 185                 else if (!op->replace)
 186                         set_closure_fn(cl, bch_data_insert_error, op->wq);
 187                 else
 188                         set_closure_fn(cl, NULL, NULL);
 189         }
 190
 191         bch_bbio_endio(op->c, bio, bio->bi_error, "writing data to cache");
 192 }
 193
 194 static void bch_data_insert_start(struct closure *cl)
 195 {
 196         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 197         struct bio *bio = op->bio, *n;
 198
 199         if (atomic_sub_return(bio_sectors(bio), &op->c->sectors_to_gc) < 0) {
 200                 set_gc_sectors(op->c);
 201                 wake_up_gc(op->c);
 202         }
 203
 204         if (op->bypass)
 205                 return bch_data_invalidate(cl);
 206
 207         /*
 208          * Journal writes are marked REQ_FLUSH; if the original write was a
 209          * flush, it'll wait on the journal write.
 210          */
 211         bio->bi_rw &= ~(REQ_FLUSH|REQ_FUA);
 212
 213         do {
 214                 unsigned i;
 215                 struct bkey *k;
 216                 struct bio_set *split = op->c->bio_split;
 217
 218                 /* 1 for the device pointer and 1 for the chksum */
 219                 if (bch_keylist_realloc(&op->insert_keys,
 220                                         3 + (op->csum ? 1 : 0),
 221                                         op->c)) {
 222                         continue_at(cl, bch_data_insert_keys, op->wq);
 223                         return;
 224                 }
 225
 226                 k = op->insert_keys.top;
 227                 bkey_init(k);
 228                 SET_KEY_INODE(k, op->inode);
 229                 SET_KEY_OFFSET(k, bio->bi_iter.bi_sector);
 230
 231                 if (!bch_alloc_sectors(op->c, k, bio_sectors(bio),
 232                                        op->write_point, op->write_prio,
 233                                        op->writeback))
 234                         goto err;
 235
 236                 n = bio_next_split(bio, KEY_SIZE(k), GFP_NOIO, split);
 237
 238                 n->bi_end_io    = bch_data_insert_endio;
 239                 n->bi_private   = cl;
 240
 241                 if (op->writeback) {
 242                         SET_KEY_DIRTY(k, true);
 243
 244                         for (i = 0; i < KEY_PTRS(k); i++)
 245                                 SET_GC_MARK(PTR_BUCKET(op->c, k, i),
 246                                             GC_MARK_DIRTY);
 247                 }
 248
 249                 SET_KEY_CSUM(k, op->csum);
 250                 if (KEY_CSUM(k))
 251                         bio_csum(n, k);
 252
 253                 trace_bcache_cache_insert(k);
 254                 bch_keylist_push(&op->insert_keys);
 255
 256                 n->bi_rw |= REQ_WRITE;
 257                 bch_submit_bbio(n, op->c, k, 0);
 258         } while (n != bio);
 259
 260         op->insert_data_done = true;
 261         continue_at(cl, bch_data_insert_keys, op->wq);
 262         return;
 263 err:
 264         /* bch_alloc_sectors() blocks if s->writeback = true */
 265         BUG_ON(op->writeback);
 266
 267         /*
 268          * But if it's not a writeback write we'd rather just bail out if
 269          * there aren't any buckets ready to write to - it might take awhile and
 270          * we might be starving btree writes for gc or something.
 271          */
 272
 273         if (!op->replace) {
 274                 /*
 275                  * Writethrough write: We can't complete the write until we've
 276                  * updated the index. But we don't want to delay the write while
 277                  * we wait for buckets to be freed up, so just invalidate the
 278                  * rest of the write.
 279                  */
 280                 op->bypass = true;
 281                 return bch_data_invalidate(cl);
 282         } else {
 283                 /*
 284                  * From a cache miss, we can just insert the keys for the data
 285                  * we have written or bail out if we didn't do anything.
 286                  */
 287                 op->insert_data_done = true;
 288                 bio_put(bio);
 289
 290                 if (!bch_keylist_empty(&op->insert_keys))
 291                         continue_at(cl, bch_data_insert_keys, op->wq);
 292                 else
 293                         closure_return(cl);
 294         }
 295 }
 296
 297 /**
 298  * bch_data_insert - stick some data in the cache
 299  *
 300  * This is the starting point for any data to end up in a cache device; it could
 301  * be from a normal write, or a writeback write, or a write to a flash only
 302  * volume - it's also used by the moving garbage collector to compact data in
 303  * mostly empty buckets.
 304  *
 305  * It first writes the data to the cache, creating a list of keys to be inserted
 306  * (if the data had to be fragmented there will be multiple keys); after the
 307  * data is written it calls bch_journal, and after the keys have been added to
 308  * the next journal write they're inserted into the btree.
 309  *
 310  * It inserts the data in s->cache_bio; bi_sector is used for the key offset,
 311  * and op->inode is used for the key inode.
 312  *
 313  * If s->bypass is true, instead of inserting the data it invalidates the
 314  * region of the cache represented by s->cache_bio and op->inode.
 315  */
 316 void bch_data_insert(struct closure *cl)
 317 {
 318         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 319
 320         trace_bcache_write(op->c, op->inode, op->bio,
 321                            op->writeback, op->bypass);
 322
 323         bch_keylist_init(&op->insert_keys);
 324         bio_get(op->bio);
 325         bch_data_insert_start(cl);
 326 }
 327
 328 /* Congested? */
 329
 330 unsigned bch_get_congested(struct cache_set *c)
 331 {
 332         int i;
 333         long rand;
 334
 335         if (!c->congested_read_threshold_us &&
 336             !c->congested_write_threshold_us)
 337                 return 0;
 338
 339         i = (local_clock_us() - c->congested_last_us) / 1024;
 340         if (i < 0)
 341                 return 0;
 342
 343         i += atomic_read(&c->congested);
 344         if (i >= 0)
 345                 return 0;
 346
 347         i += CONGESTED_MAX;
 348
 349         if (i > 0)
 350                 i = fract_exp_two(i, 6);
 351
 352         rand = get_random_int();
 353         i -= bitmap_weight(&rand, BITS_PER_LONG);
 354
 355         return i > 0 ? i : 1;
 356 }
 357
 358 static void add_sequential(struct task_struct *t)
 359 {
 360         ewma_add(t->sequential_io_avg,
 361                  t->sequential_io, 8, 0);
 362
 363         t->sequential_io = 0;
 364 }
 365
 366 static struct hlist_head *iohash(struct cached_dev *dc, uint64_t k)
 367 {
 368         return &dc->io_hash[hash_64(k, RECENT_IO_BITS)];
 369 }
 370
 371 static bool check_should_bypass(struct cached_dev *dc, struct bio *bio)
 372 {
 373         struct cache_set *c = dc->disk.c;
 374         unsigned mode = cache_mode(dc, bio);
 375         unsigned sectors, congested = bch_get_congested(c);
 376         struct task_struct *task = current;
 377         struct io *i;
 378
 379         if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
 380             c->gc_stats.in_use > CUTOFF_CACHE_ADD ||
 381             (bio->bi_rw & REQ_DISCARD))
 382                 goto skip;
 383
 384         if (mode == CACHE_MODE_NONE ||
 385             (mode == CACHE_MODE_WRITEAROUND &&
 386              (bio->bi_rw & REQ_WRITE)))
 387                 goto skip;
 388
 389         if (bio->bi_iter.bi_sector & (c->sb.block_size - 1) ||
 390             bio_sectors(bio) & (c->sb.block_size - 1)) {
 391                 pr_debug("skipping unaligned io");
 392                 goto skip;
 393         }
 394
 395         if (bypass_torture_test(dc)) {
 396                 if ((get_random_int() & 3) == 3)
 397                         goto skip;
 398                 else
 399                         goto rescale;
 400         }
 401
 402         if (!congested && !dc->sequential_cutoff)
 403                 goto rescale;
 404
 405         if (!congested &&
 406             mode == CACHE_MODE_WRITEBACK &&
 407             (bio->bi_rw & REQ_WRITE) &&
 408             (bio->bi_rw & REQ_SYNC))
 409                 goto rescale;
 410
 411         spin_lock(&dc->io_lock);
 412
 413         hlist_for_each_entry(i, iohash(dc, bio->bi_iter.bi_sector), hash)
 414                 if (i->last == bio->bi_iter.bi_sector &&
 415                     time_before(jiffies, i->jiffies))
 416                         goto found;
 417
 418         i = list_first_entry(&dc->io_lru, struct io, lru);
 419
 420         add_sequential(task);
 421         i->sequential = 0;
 422 found:
 423         if (i->sequential + bio->bi_iter.bi_size > i->sequential)
 424                 i->sequential   += bio->bi_iter.bi_size;
 425
 426         i->last                  = bio_end_sector(bio);
 427         i->jiffies               = jiffies + msecs_to_jiffies(5000);
 428         task->sequential_io      = i->sequential;
 429
 430         hlist_del(&i->hash);
 431         hlist_add_head(&i->hash, iohash(dc, i->last));
 432         list_move_tail(&i->lru, &dc->io_lru);
 433
 434         spin_unlock(&dc->io_lock);
 435
 436         sectors = max(task->sequential_io,
 437                       task->sequential_io_avg) >> 9;
 438
 439         if (dc->sequential_cutoff &&
 440             sectors >= dc->sequential_cutoff >> 9) {
 441                 trace_bcache_bypass_sequential(bio);
 442                 goto skip;
 443         }
 444
 445         if (congested && sectors >= congested) {
 446                 trace_bcache_bypass_congested(bio);
 447                 goto skip;
 448         }
 449
 450 rescale:
 451         bch_rescale_priorities(c, bio_sectors(bio));
 452         return false;
 453 skip:
 454         bch_mark_sectors_bypassed(c, dc, bio_sectors(bio));
 455         return true;
 456 }
 457
 458 /* Cache lookup */
 459
 460 struct search {
 461         /* Stack frame for bio_complete */
 462         struct closure          cl;
 463
 464         struct bbio             bio;
 465         struct bio              *orig_bio;
 466         struct bio              *cache_miss;
 467         struct bcache_device    *d;
 468
 469         unsigned                insert_bio_sectors;
 470         unsigned                recoverable:1;
 471         unsigned                write:1;
 472         unsigned                read_dirty_data:1;
 473
 474         unsigned long           start_time;
 475
 476         struct btree_op         op;
 477         struct data_insert_op   iop;
 478 };
 479
 480 static void bch_cache_read_endio(struct bio *bio)
 481 {
 482         struct bbio *b = container_of(bio, struct bbio, bio);
 483         struct closure *cl = bio->bi_private;
 484         struct search *s = container_of(cl, struct search, cl);
 485
 486         /*
 487          * If the bucket was reused while our bio was in flight, we might have
 488          * read the wrong data. Set s->error but not error so it doesn't get
 489          * counted against the cache device, but we'll still reread the data
 490          * from the backing device.
 491          */
 492
 493         if (bio->bi_error)
 494                 s->iop.error = bio->bi_error;
 495         else if (!KEY_DIRTY(&b->key) &&
 496                  ptr_stale(s->iop.c, &b->key, 0)) {
 497                 atomic_long_inc(&s->iop.c->cache_read_races);
 498                 s->iop.error = -EINTR;
 499         }
 500
 501         bch_bbio_endio(s->iop.c, bio, bio->bi_error, "reading from cache");
 502 }
 503
 504 /*
 505  * Read from a single key, handling the initial cache miss if the key starts in
 506  * the middle of the bio
 507  */
 508 static int cache_lookup_fn(struct btree_op *op, struct btree *b, struct bkey *k)
 509 {
 510         struct search *s = container_of(op, struct search, op);
 511         struct bio *n, *bio = &s->bio.bio;
 512         struct bkey *bio_key;
 513         unsigned ptr;
 514
 515         if (bkey_cmp(k, &KEY(s->iop.inode, bio->bi_iter.bi_sector, 0)) <= 0)
 516                 return MAP_CONTINUE;
 517
 518         if (KEY_INODE(k) != s->iop.inode ||
 519             KEY_START(k) > bio->bi_iter.bi_sector) {
 520                 unsigned bio_sectors = bio_sectors(bio);
 521                 unsigned sectors = KEY_INODE(k) == s->iop.inode
 522                         ? min_t(uint64_t, INT_MAX,
 523                                 KEY_START(k) - bio->bi_iter.bi_sector)
 524                         : INT_MAX;
 525
 526                 int ret = s->d->cache_miss(b, s, bio, sectors);
 527                 if (ret != MAP_CONTINUE)
 528                         return ret;
 529
 530                 /* if this was a complete miss we shouldn't get here */
 531                 BUG_ON(bio_sectors <= sectors);
 532         }
 533
 534         if (!KEY_SIZE(k))
 535                 return MAP_CONTINUE;
 536
 537         /* XXX: figure out best pointer - for multiple cache devices */
 538         ptr = 0;
 539
 540         PTR_BUCKET(b->c, k, ptr)->prio = INITIAL_PRIO;
 541
 542         if (KEY_DIRTY(k))
 543                 s->read_dirty_data = true;
 544
 545         n = bio_next_split(bio, min_t(uint64_t, INT_MAX,
 546                                       KEY_OFFSET(k) - bio->bi_iter.bi_sector),
 547                            GFP_NOIO, s->d->bio_split);
 548
 549         bio_key = &container_of(n, struct bbio, bio)->key;
 550         bch_bkey_copy_single_ptr(bio_key, k, ptr);
 551
 552         bch_cut_front(&KEY(s->iop.inode, n->bi_iter.bi_sector, 0), bio_key);
 553         bch_cut_back(&KEY(s->iop.inode, bio_end_sector(n), 0), bio_key);
 554
 555         n->bi_end_io    = bch_cache_read_endio;
 556         n->bi_private   = &s->cl;
 557
 558         /*
 559          * The bucket we're reading from might be reused while our bio
 560          * is in flight, and we could then end up reading the wrong
 561          * data.
 562          *
 563          * We guard against this by checking (in cache_read_endio()) if
 564          * the pointer is stale again; if so, we treat it as an error
 565          * and reread from the backing device (but we don't pass that
 566          * error up anywhere).
 567          */
 568
 569         __bch_submit_bbio(n, b->c);
 570         return n == bio ? MAP_DONE : MAP_CONTINUE;
 571 }
 572
 573 static void cache_lookup(struct closure *cl)
 574 {
 575         struct search *s = container_of(cl, struct search, iop.cl);
 576         struct bio *bio = &s->bio.bio;
 577         int ret;
 578
 579         bch_btree_op_init(&s->op, -1);
 580
 581         ret = bch_btree_map_keys(&s->op, s->iop.c,
 582                                  &KEY(s->iop.inode, bio->bi_iter.bi_sector, 0),
 583                                  cache_lookup_fn, MAP_END_KEY);
 584         if (ret == -EAGAIN) {
 585                 continue_at(cl, cache_lookup, bcache_wq);
 586                 return;
 587         }
 588
 589         closure_return(cl);
 590 }
 591
 592 /* Common code for the make_request functions */
 593
 594 static void request_endio(struct bio *bio)
 595 {
 596         struct closure *cl = bio->bi_private;
 597
 598         if (bio->bi_error) {
 599                 struct search *s = container_of(cl, struct search, cl);
 600                 s->iop.error = bio->bi_error;
 601                 /* Only cache read errors are recoverable */
 602                 s->recoverable = false;
 603         }
 604
 605         bio_put(bio);
 606         closure_put(cl);
 607 }
 608
 609 static void bio_complete(struct search *s)
 610 {
 611         if (s->orig_bio) {
 612                 generic_end_io_acct(bio_data_dir(s->orig_bio),
 613                                     &s->d->disk->part0, s->start_time);
 614
 615                 trace_bcache_request_end(s->d, s->orig_bio);
 616                 s->orig_bio->bi_error = s->iop.error;
 617                 bio_endio(s->orig_bio);
 618                 s->orig_bio = NULL;
 619         }
 620 }
 621
 622 static void do_bio_hook(struct search *s, struct bio *orig_bio)
 623 {
 624         struct bio *bio = &s->bio.bio;
 625
 626         bio_init(bio);
 627         __bio_clone_fast(bio, orig_bio);
 628         bio->bi_end_io          = request_endio;
 629         bio->bi_private         = &s->cl;
 630
 631         bio_cnt_set(bio, 3);
 632 }
 633
 634 static void search_free(struct closure *cl)
 635 {
 636         struct search *s = container_of(cl, struct search, cl);
 637         bio_complete(s);
 638
 639         if (s->iop.bio)
 640                 bio_put(s->iop.bio);
 641
 642         closure_debug_destroy(cl);
 643         mempool_free(s, s->d->c->search);
 644 }
 645
 646 static inline struct search *search_alloc(struct bio *bio,
 647                                           struct bcache_device *d)
 648 {
 649         struct search *s;
 650
 651         s = mempool_alloc(d->c->search, GFP_NOIO);
 652
 653         closure_init(&s->cl, NULL);
 654         do_bio_hook(s, bio);
 655
 656         s->orig_bio             = bio;
 657         s->cache_miss           = NULL;
 658         s->d                    = d;
 659         s->recoverable          = 1;
 660         s->write                = (bio->bi_rw & REQ_WRITE) != 0;
 661         s->read_dirty_data      = 0;
 662         s->start_time           = jiffies;
 663
 664         s->iop.c                = d->c;
 665         s->iop.bio              = NULL;
 666         s->iop.inode            = d->id;
 667         s->iop.write_point      = hash_long((unsigned long) current, 16);
 668         s->iop.write_prio       = 0;
 669         s->iop.error            = 0;
 670         s->iop.flags            = 0;
 671         s->iop.flush_journal    = (bio->bi_rw & (REQ_FLUSH|REQ_FUA)) != 0;
 672         s->iop.wq               = bcache_wq;
 673
 674         return s;
 675 }
 676
 677 /* Cached devices */
 678
 679 static void cached_dev_bio_complete(struct closure *cl)
 680 {
 681         struct search *s = container_of(cl, struct search, cl);
 682         struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 683
 684         search_free(cl);
 685         cached_dev_put(dc);
 686 }
 687
 688 /* Process reads */
 689
 690 static void cached_dev_cache_miss_done(struct closure *cl)
 691 {
 692         struct search *s = container_of(cl, struct search, cl);
 693
 694         if (s->iop.replace_collision)
 695                 bch_mark_cache_miss_collision(s->iop.c, s->d);
 696
 697         if (s->iop.bio) {
 698                 int i;
 699                 struct bio_vec *bv;
 700
 701                 bio_for_each_segment_all(bv, s->iop.bio, i)
 702                         __free_page(bv->bv_page);
 703         }
 704
 705         cached_dev_bio_complete(cl);
 706 }
 707
 708 static void cached_dev_read_error(struct closure *cl)
 709 {
 710         struct search *s = container_of(cl, struct search, cl);
 711         struct bio *bio = &s->bio.bio;
 712
 713         if (s->recoverable) {
 714                 /* Retry from the backing device: */
 715                 trace_bcache_read_retry(s->orig_bio);
 716
 717                 s->iop.error = 0;
 718                 do_bio_hook(s, s->orig_bio);
 719
 720                 /* XXX: invalidate cache */
 721
 722                 closure_bio_submit(bio, cl);
 723         }
 724
 725         continue_at(cl, cached_dev_cache_miss_done, NULL);
 726 }
 727
 728 static void cached_dev_read_done(struct closure *cl)
 729 {
 730         struct search *s = container_of(cl, struct search, cl);
 731         struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 732
 733         /*
 734          * We had a cache miss; cache_bio now contains data ready to be inserted
 735          * into the cache.
 736          *
 737          * First, we copy the data we just read from cache_bio's bounce buffers
 738          * to the buffers the original bio pointed to:
 739          */
 740
 741         if (s->iop.bio) {
 742                 bio_reset(s->iop.bio);
 743                 s->iop.bio->bi_iter.bi_sector = s->cache_miss->bi_iter.bi_sector;
 744                 s->iop.bio->bi_bdev = s->cache_miss->bi_bdev;
 745                 s->iop.bio->bi_iter.bi_size = s->insert_bio_sectors << 9;
 746                 bch_bio_map(s->iop.bio, NULL);
 747
 748                 bio_copy_data(s->cache_miss, s->iop.bio);
 749
 750                 bio_put(s->cache_miss);
 751                 s->cache_miss = NULL;
 752         }
 753
 754         if (verify(dc, &s->bio.bio) && s->recoverable && !s->read_dirty_data)
 755                 bch_data_verify(dc, s->orig_bio);
 756
 757         bio_complete(s);
 758
 759         if (s->iop.bio &&
 760             !test_bit(CACHE_SET_STOPPING, &s->iop.c->flags)) {
 761                 BUG_ON(!s->iop.replace);
 762                 closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
 763         }
 764
 765         continue_at(cl, cached_dev_cache_miss_done, NULL);
 766 }
 767
 768 static void cached_dev_read_done_bh(struct closure *cl)
 769 {
 770         struct search *s = container_of(cl, struct search, cl);
 771         struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 772
 773         bch_mark_cache_accounting(s->iop.c, s->d,
 774                                   !s->cache_miss, s->iop.bypass);
 775         trace_bcache_read(s->orig_bio, !s->cache_miss, s->iop.bypass);
 776
 777         if (s->iop.error)
 778                 continue_at_nobarrier(cl, cached_dev_read_error, bcache_wq);
 779         else if (s->iop.bio || verify(dc, &s->bio.bio))
 780                 continue_at_nobarrier(cl, cached_dev_read_done, bcache_wq);
 781         else
 782                 continue_at_nobarrier(cl, cached_dev_bio_complete, NULL);
 783 }
 784
 785 static int cached_dev_cache_miss(struct btree *b, struct search *s,
 786                                  struct bio *bio, unsigned sectors)
 787 {
 788         int ret = MAP_CONTINUE;
 789         unsigned reada = 0;
 790         struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 791         struct bio *miss, *cache_bio;
 792
 793         if (s->cache_miss || s->iop.bypass) {
 794                 miss = bio_next_split(bio, sectors, GFP_NOIO, s->d->bio_split);
 795                 ret = miss == bio ? MAP_DONE : MAP_CONTINUE;
 796                 goto out_submit;
 797         }
 798
 799         if (!(bio->bi_rw & REQ_RAHEAD) &&
 800             !(bio->bi_rw & REQ_META) &&
 801             s->iop.c->gc_stats.in_use < CUTOFF_CACHE_READA)
 802                 reada = min_t(sector_t, dc->readahead >> 9,
 803                               bdev_sectors(bio->bi_bdev) - bio_end_sector(bio));
 804
 805         s->insert_bio_sectors = min(sectors, bio_sectors(bio) + reada);
 806
 807         s->iop.replace_key = KEY(s->iop.inode,
 808                                  bio->bi_iter.bi_sector + s->insert_bio_sectors,
 809                                  s->insert_bio_sectors);
 810
 811         ret = bch_btree_insert_check_key(b, &s->op, &s->iop.replace_key);
 812         if (ret)
 813                 return ret;
 814
 815         s->iop.replace = true;
 816
 817         miss = bio_next_split(bio, sectors, GFP_NOIO, s->d->bio_split);
 818
 819         /* btree_search_recurse()'s btree iterator is no good anymore */
 820         ret = miss == bio ? MAP_DONE : -EINTR;
 821
 822         cache_bio = bio_alloc_bioset(GFP_NOWAIT,
 823                         DIV_ROUND_UP(s->insert_bio_sectors, PAGE_SECTORS),
 824                         dc->disk.bio_split);
 825         if (!cache_bio)
 826                 goto out_submit;
 827
 828         cache_bio->bi_iter.bi_sector    = miss->bi_iter.bi_sector;
 829         cache_bio->bi_bdev              = miss->bi_bdev;
 830         cache_bio->bi_iter.bi_size      = s->insert_bio_sectors << 9;
 831
 832         cache_bio->bi_end_io    = request_endio;
 833         cache_bio->bi_private   = &s->cl;
 834
 835         bch_bio_map(cache_bio, NULL);
 836         if (bio_alloc_pages(cache_bio, __GFP_NOWARN|GFP_NOIO))
 837                 goto out_put;
 838
 839         if (reada)
 840                 bch_mark_cache_readahead(s->iop.c, s->d);
 841
 842         s->cache_miss   = miss;
 843         s->iop.bio      = cache_bio;
 844         bio_get(cache_bio);
 845         closure_bio_submit(cache_bio, &s->cl);
 846
 847         return ret;
 848 out_put:
 849         bio_put(cache_bio);
 850 out_submit:
 851         miss->bi_end_io         = request_endio;
 852         miss->bi_private        = &s->cl;
 853         closure_bio_submit(miss, &s->cl);
 854         return ret;
 855 }
 856
 857 static void cached_dev_read(struct cached_dev *dc, struct search *s)
 858 {
 859         struct closure *cl = &s->cl;
 860
 861         closure_call(&s->iop.cl, cache_lookup, NULL, cl);
 862         continue_at(cl, cached_dev_read_done_bh, NULL);
 863 }
 864
 865 /* Process writes */
 866
 867 static void cached_dev_write_complete(struct closure *cl)
 868 {
 869         struct search *s = container_of(cl, struct search, cl);
 870         struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 871
 872         up_read_non_owner(&dc->writeback_lock);
 873         cached_dev_bio_complete(cl);
 874 }
 875
 876 static void cached_dev_write(struct cached_dev *dc, struct search *s)
 877 {
 878         struct closure *cl = &s->cl;
 879         struct bio *bio = &s->bio.bio;
 880         struct bkey start = KEY(dc->disk.id, bio->bi_iter.bi_sector, 0);
 881         struct bkey end = KEY(dc->disk.id, bio_end_sector(bio), 0);
 882
 883         bch_keybuf_check_overlapping(&s->iop.c->moving_gc_keys, &start, &end);
 884
 885         down_read_non_owner(&dc->writeback_lock);
 886         if (bch_keybuf_check_overlapping(&dc->writeback_keys, &start, &end)) {
 887                 /*
 888                  * We overlap with some dirty data undergoing background
 889                  * writeback, force this write to writeback
 890                  */
 891                 s->iop.bypass = false;
 892                 s->iop.writeback = true;
 893         }
 894
 895         /*
 896          * Discards aren't _required_ to do anything, so skipping if
 897          * check_overlapping returned true is ok
 898          *
 899          * But check_overlapping drops dirty keys for which io hasn't started,
 900          * so we still want to call it.
 901          */
 902         if (bio->bi_rw & REQ_DISCARD)
 903                 s->iop.bypass = true;
 904
 905         if (should_writeback(dc, s->orig_bio,
 906                              cache_mode(dc, bio),
 907                              s->iop.bypass)) {
 908                 s->iop.bypass = false;
 909                 s->iop.writeback = true;
 910         }
 911
 912         if (s->iop.bypass) {
 913                 s->iop.bio = s->orig_bio;
 914                 bio_get(s->iop.bio);
 915
 916                 if (!(bio->bi_rw & REQ_DISCARD) ||
 917                     blk_queue_discard(bdev_get_queue(dc->bdev)))
 918                         closure_bio_submit(bio, cl);
 919         } else if (s->iop.writeback) {
 920                 bch_writeback_add(dc);
 921                 s->iop.bio = bio;
 922
 923                 if (bio->bi_rw & REQ_FLUSH) {
 924                         /* Also need to send a flush to the backing device */
 925                         struct bio *flush = bio_alloc_bioset(GFP_NOIO, 0,
 926                                                              dc->disk.bio_split);
 927
 928                         flush->bi_rw    = WRITE_FLUSH;
 929                         flush->bi_bdev  = bio->bi_bdev;
 930                         flush->bi_end_io = request_endio;
 931                         flush->bi_private = cl;
 932
 933                         closure_bio_submit(flush, cl);
 934                 }
 935         } else {
 936                 s->iop.bio = bio_clone_fast(bio, GFP_NOIO, dc->disk.bio_split);
 937
 938                 closure_bio_submit(bio, cl);
 939         }
 940
 941         closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
 942         continue_at(cl, cached_dev_write_complete, NULL);
 943 }
 944
 945 static void cached_dev_nodata(struct closure *cl)
 946 {
 947         struct search *s = container_of(cl, struct search, cl);
 948         struct bio *bio = &s->bio.bio;
 949
 950         if (s->iop.flush_journal)
 951                 bch_journal_meta(s->iop.c, cl);
 952
 953         /* If it's a flush, we send the flush to the backing device too */
 954         closure_bio_submit(bio, cl);
 955
 956         continue_at(cl, cached_dev_bio_complete, NULL);
 957 }
 958
 959 /* Cached devices - read & write stuff */
 960
 961 static void cached_dev_make_request(struct request_queue *q, struct bio *bio)
 962 {
 963         struct search *s;
 964         struct bcache_device *d = bio->bi_bdev->bd_disk->private_data;
 965         struct cached_dev *dc = container_of(d, struct cached_dev, disk);
 966         int rw = bio_data_dir(bio);
 967
 968         generic_start_io_acct(rw, bio_sectors(bio), &d->disk->part0);
 969
 970         bio->bi_bdev = dc->bdev;
 971         bio->bi_iter.bi_sector += dc->sb.data_offset;
 972
 973         if (cached_dev_get(dc)) {
 974                 s = search_alloc(bio, d);
 975                 trace_bcache_request_start(s->d, bio);
 976
 977                 if (!bio->bi_iter.bi_size) {
 978                         /*
 979                          * can't call bch_journal_meta from under
 980                          * generic_make_request
 981                          */
 982                         continue_at_nobarrier(&s->cl,
 983                                               cached_dev_nodata,
 984                                               bcache_wq);
 985                 } else {
 986                         s->iop.bypass = check_should_bypass(dc, bio);
 987
 988                         if (rw)
 989                                 cached_dev_write(dc, s);
 990                         else
 991                                 cached_dev_read(dc, s);
 992                 }
 993         } else {
 994                 if ((bio->bi_rw & REQ_DISCARD) &&
 995                     !blk_queue_discard(bdev_get_queue(dc->bdev)))
 996                         bio_endio(bio);
 997                 else
 998                         generic_make_request(bio);
 999         }
1000 }
1001
1002 static int cached_dev_ioctl(struct bcache_device *d, fmode_t mode,
1003                             unsigned int cmd, unsigned long arg)
1004 {
1005         struct cached_dev *dc = container_of(d, struct cached_dev, disk);
1006         return __blkdev_driver_ioctl(dc->bdev, mode, cmd, arg);
1007 }
1008
1009 static int cached_dev_congested(void *data, int bits)
1010 {
1011         struct bcache_device *d = data;
1012         struct cached_dev *dc = container_of(d, struct cached_dev, disk);
1013         struct request_queue *q = bdev_get_queue(dc->bdev);
1014         int ret = 0;
1015
1016         if (bdi_congested(&q->backing_dev_info, bits))
1017                 return 1;
1018
1019         if (cached_dev_get(dc)) {
1020                 unsigned i;
1021                 struct cache *ca;
1022
1023                 for_each_cache(ca, d->c, i) {
1024                         q = bdev_get_queue(ca->bdev);
1025                         ret |= bdi_congested(&q->backing_dev_info, bits);
1026                 }
1027
1028                 cached_dev_put(dc);
1029         }
1030
1031         return ret;
1032 }
1033
1034 void bch_cached_dev_request_init(struct cached_dev *dc)
1035 {
1036         struct gendisk *g = dc->disk.disk;
1037
1038         g->queue->make_request_fn               = cached_dev_make_request;
1039         g->queue->backing_dev_info.congested_fn = cached_dev_congested;
1040         dc->disk.cache_miss                     = cached_dev_cache_miss;
1041         dc->disk.ioctl                          = cached_dev_ioctl;
1042 }
1043
1044 /* Flash backed devices */
1045
1046 static int flash_dev_cache_miss(struct btree *b, struct search *s,
1047                                 struct bio *bio, unsigned sectors)
1048 {
1049         unsigned bytes = min(sectors, bio_sectors(bio)) << 9;
1050
1051         swap(bio->bi_iter.bi_size, bytes);
1052         zero_fill_bio(bio);
1053         swap(bio->bi_iter.bi_size, bytes);
1054
1055         bio_advance(bio, bytes);
1056
1057         if (!bio->bi_iter.bi_size)
1058                 return MAP_DONE;
1059
1060         return MAP_CONTINUE;
1061 }
1062
1063 static void flash_dev_nodata(struct closure *cl)
1064 {
1065         struct search *s = container_of(cl, struct search, cl);
1066
1067         if (s->iop.flush_journal)
1068                 bch_journal_meta(s->iop.c, cl);
1069
1070         continue_at(cl, search_free, NULL);
1071 }
1072
1073 static void flash_dev_make_request(struct request_queue *q, struct bio *bio)
1074 {
1075         struct search *s;
1076         struct closure *cl;
1077         struct bcache_device *d = bio->bi_bdev->bd_disk->private_data;
1078         int rw = bio_data_dir(bio);
1079
1080         generic_start_io_acct(rw, bio_sectors(bio), &d->disk->part0);
1081
1082         s = search_alloc(bio, d);
1083         cl = &s->cl;
1084         bio = &s->bio.bio;
1085
1086         trace_bcache_request_start(s->d, bio);
1087
1088         if (!bio->bi_iter.bi_size) {
1089                 /*
1090                  * can't call bch_journal_meta from under
1091                  * generic_make_request
1092                  */
1093                 continue_at_nobarrier(&s->cl,
1094                                       flash_dev_nodata,
1095                                       bcache_wq);
1096                 return;
1097         } else if (rw) {
1098                 bch_keybuf_check_overlapping(&s->iop.c->moving_gc_keys,
1099                                         &KEY(d->id, bio->bi_iter.bi_sector, 0),
1100                                         &KEY(d->id, bio_end_sector(bio), 0));
1101
1102                 s->iop.bypass           = (bio->bi_rw & REQ_DISCARD) != 0;
1103                 s->iop.writeback        = true;
1104                 s->iop.bio              = bio;
1105
1106                 closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
1107         } else {
1108                 closure_call(&s->iop.cl, cache_lookup, NULL, cl);
1109         }
1110
1111         continue_at(cl, search_free, NULL);
1112 }
1113
1114 static int flash_dev_ioctl(struct bcache_device *d, fmode_t mode,
1115                            unsigned int cmd, unsigned long arg)
1116 {
1117         return -ENOTTY;
1118 }
1119
1120 static int flash_dev_congested(void *data, int bits)
1121 {
1122         struct bcache_device *d = data;
1123         struct request_queue *q;
1124         struct cache *ca;
1125         unsigned i;
1126         int ret = 0;
1127
1128         for_each_cache(ca, d->c, i) {
1129                 q = bdev_get_queue(ca->bdev);
1130                 ret |= bdi_congested(&q->backing_dev_info, bits);
1131         }
1132
1133         return ret;
1134 }
1135
1136 void bch_flash_dev_request_init(struct bcache_device *d)
1137 {
1138         struct gendisk *g = d->disk;
1139
1140         g->queue->make_request_fn               = flash_dev_make_request;
1141         g->queue->backing_dev_info.congested_fn = flash_dev_congested;
1142         d->cache_miss                           = flash_dev_cache_miss;
1143         d->ioctl                                = flash_dev_ioctl;
1144 }
1145
1146 void bch_request_exit(void)
1147 {
1148         if (bch_search_cache)
1149                 kmem_cache_destroy(bch_search_cache);
1150 }
1151
1152 int __init bch_request_init(void)
1153 {
1154         bch_search_cache = KMEM_CACHE(search, 0);
1155         if (!bch_search_cache)
1156                 return -ENOMEM;
1157
1158         return 0;
1159 }