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