Pileus Git - ~andy/linux/blob - 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/cgroup.h>
  16 #include <linux/module.h>
  17 #include <linux/hash.h>
  18 #include <linux/random.h>
  19 #include "blk-cgroup.h"
  20
  21 #include <trace/events/bcache.h>
  22
  23 #define CUTOFF_CACHE_ADD        95
  24 #define CUTOFF_CACHE_READA      90
  25
  26 struct kmem_cache *bch_search_cache;
  27
  28 static void bch_data_insert_start(struct closure *);
  29
  30 /* Cgroup interface */
  31
  32 #ifdef CONFIG_CGROUP_BCACHE
  33 static struct bch_cgroup bcache_default_cgroup = { .cache_mode = -1 };
  34
  35 static struct bch_cgroup *cgroup_to_bcache(struct cgroup *cgroup)
  36 {
  37         struct cgroup_subsys_state *css;
  38         return cgroup &&
  39                 (css = cgroup_subsys_state(cgroup, bcache_subsys_id))
  40                 ? container_of(css, struct bch_cgroup, css)
  41                 : &bcache_default_cgroup;
  42 }
  43
  44 struct bch_cgroup *bch_bio_to_cgroup(struct bio *bio)
  45 {
  46         struct cgroup_subsys_state *css = bio->bi_css
  47                 ? cgroup_subsys_state(bio->bi_css->cgroup, bcache_subsys_id)
  48                 : task_subsys_state(current, bcache_subsys_id);
  49
  50         return css
  51                 ? container_of(css, struct bch_cgroup, css)
  52                 : &bcache_default_cgroup;
  53 }
  54
  55 static ssize_t cache_mode_read(struct cgroup *cgrp, struct cftype *cft,
  56                         struct file *file,
  57                         char __user *buf, size_t nbytes, loff_t *ppos)
  58 {
  59         char tmp[1024];
  60         int len = bch_snprint_string_list(tmp, PAGE_SIZE, bch_cache_modes,
  61                                           cgroup_to_bcache(cgrp)->cache_mode + 1);
  62
  63         if (len < 0)
  64                 return len;
  65
  66         return simple_read_from_buffer(buf, nbytes, ppos, tmp, len);
  67 }
  68
  69 static int cache_mode_write(struct cgroup *cgrp, struct cftype *cft,
  70                             const char *buf)
  71 {
  72         int v = bch_read_string_list(buf, bch_cache_modes);
  73         if (v < 0)
  74                 return v;
  75
  76         cgroup_to_bcache(cgrp)->cache_mode = v - 1;
  77         return 0;
  78 }
  79
  80 static u64 bch_verify_read(struct cgroup *cgrp, struct cftype *cft)
  81 {
  82         return cgroup_to_bcache(cgrp)->verify;
  83 }
  84
  85 static int bch_verify_write(struct cgroup *cgrp, struct cftype *cft, u64 val)
  86 {
  87         cgroup_to_bcache(cgrp)->verify = val;
  88         return 0;
  89 }
  90
  91 static u64 bch_cache_hits_read(struct cgroup *cgrp, struct cftype *cft)
  92 {
  93         struct bch_cgroup *bcachecg = cgroup_to_bcache(cgrp);
  94         return atomic_read(&bcachecg->stats.cache_hits);
  95 }
  96
  97 static u64 bch_cache_misses_read(struct cgroup *cgrp, struct cftype *cft)
  98 {
  99         struct bch_cgroup *bcachecg = cgroup_to_bcache(cgrp);
 100         return atomic_read(&bcachecg->stats.cache_misses);
 101 }
 102
 103 static u64 bch_cache_bypass_hits_read(struct cgroup *cgrp,
 104                                          struct cftype *cft)
 105 {
 106         struct bch_cgroup *bcachecg = cgroup_to_bcache(cgrp);
 107         return atomic_read(&bcachecg->stats.cache_bypass_hits);
 108 }
 109
 110 static u64 bch_cache_bypass_misses_read(struct cgroup *cgrp,
 111                                            struct cftype *cft)
 112 {
 113         struct bch_cgroup *bcachecg = cgroup_to_bcache(cgrp);
 114         return atomic_read(&bcachecg->stats.cache_bypass_misses);
 115 }
 116
 117 static struct cftype bch_files[] = {
 118         {
 119                 .name           = "cache_mode",
 120                 .read           = cache_mode_read,
 121                 .write_string   = cache_mode_write,
 122         },
 123         {
 124                 .name           = "verify",
 125                 .read_u64       = bch_verify_read,
 126                 .write_u64      = bch_verify_write,
 127         },
 128         {
 129                 .name           = "cache_hits",
 130                 .read_u64       = bch_cache_hits_read,
 131         },
 132         {
 133                 .name           = "cache_misses",
 134                 .read_u64       = bch_cache_misses_read,
 135         },
 136         {
 137                 .name           = "cache_bypass_hits",
 138                 .read_u64       = bch_cache_bypass_hits_read,
 139         },
 140         {
 141                 .name           = "cache_bypass_misses",
 142                 .read_u64       = bch_cache_bypass_misses_read,
 143         },
 144         { }     /* terminate */
 145 };
 146
 147 static void init_bch_cgroup(struct bch_cgroup *cg)
 148 {
 149         cg->cache_mode = -1;
 150 }
 151
 152 static struct cgroup_subsys_state *bcachecg_create(struct cgroup *cgroup)
 153 {
 154         struct bch_cgroup *cg;
 155
 156         cg = kzalloc(sizeof(*cg), GFP_KERNEL);
 157         if (!cg)
 158                 return ERR_PTR(-ENOMEM);
 159         init_bch_cgroup(cg);
 160         return &cg->css;
 161 }
 162
 163 static void bcachecg_destroy(struct cgroup *cgroup)
 164 {
 165         struct bch_cgroup *cg = cgroup_to_bcache(cgroup);
 166         free_css_id(&bcache_subsys, &cg->css);
 167         kfree(cg);
 168 }
 169
 170 struct cgroup_subsys bcache_subsys = {
 171         .create         = bcachecg_create,
 172         .destroy        = bcachecg_destroy,
 173         .subsys_id      = bcache_subsys_id,
 174         .name           = "bcache",
 175         .module         = THIS_MODULE,
 176 };
 177 EXPORT_SYMBOL_GPL(bcache_subsys);
 178 #endif
 179
 180 static unsigned cache_mode(struct cached_dev *dc, struct bio *bio)
 181 {
 182 #ifdef CONFIG_CGROUP_BCACHE
 183         int r = bch_bio_to_cgroup(bio)->cache_mode;
 184         if (r >= 0)
 185                 return r;
 186 #endif
 187         return BDEV_CACHE_MODE(&dc->sb);
 188 }
 189
 190 static bool verify(struct cached_dev *dc, struct bio *bio)
 191 {
 192 #ifdef CONFIG_CGROUP_BCACHE
 193         if (bch_bio_to_cgroup(bio)->verify)
 194                 return true;
 195 #endif
 196         return dc->verify;
 197 }
 198
 199 static void bio_csum(struct bio *bio, struct bkey *k)
 200 {
 201         struct bio_vec *bv;
 202         uint64_t csum = 0;
 203         int i;
 204
 205         bio_for_each_segment(bv, bio, i) {
 206                 void *d = kmap(bv->bv_page) + bv->bv_offset;
 207                 csum = bch_crc64_update(csum, d, bv->bv_len);
 208                 kunmap(bv->bv_page);
 209         }
 210
 211         k->ptr[KEY_PTRS(k)] = csum & (~0ULL >> 1);
 212 }
 213
 214 /* Insert data into cache */
 215
 216 static void bch_data_insert_keys(struct closure *cl)
 217 {
 218         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 219         atomic_t *journal_ref = NULL;
 220         struct bkey *replace_key = op->replace ? &op->replace_key : NULL;
 221         int ret;
 222
 223         /*
 224          * If we're looping, might already be waiting on
 225          * another journal write - can't wait on more than one journal write at
 226          * a time
 227          *
 228          * XXX: this looks wrong
 229          */
 230 #if 0
 231         while (atomic_read(&s->cl.remaining) & CLOSURE_WAITING)
 232                 closure_sync(&s->cl);
 233 #endif
 234
 235         if (!op->replace)
 236                 journal_ref = bch_journal(op->c, &op->insert_keys,
 237                                           op->flush_journal ? cl : NULL);
 238
 239         ret = bch_btree_insert(op->c, &op->insert_keys,
 240                                journal_ref, replace_key);
 241         if (ret == -ESRCH) {
 242                 op->replace_collision = true;
 243         } else if (ret) {
 244                 op->error               = -ENOMEM;
 245                 op->insert_data_done    = true;
 246         }
 247
 248         if (journal_ref)
 249                 atomic_dec_bug(journal_ref);
 250
 251         if (!op->insert_data_done)
 252                 continue_at(cl, bch_data_insert_start, bcache_wq);
 253
 254         bch_keylist_free(&op->insert_keys);
 255         closure_return(cl);
 256 }
 257
 258 static void bch_data_invalidate(struct closure *cl)
 259 {
 260         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 261         struct bio *bio = op->bio;
 262
 263         pr_debug("invalidating %i sectors from %llu",
 264                  bio_sectors(bio), (uint64_t) bio->bi_sector);
 265
 266         while (bio_sectors(bio)) {
 267                 unsigned sectors = min(bio_sectors(bio),
 268                                        1U << (KEY_SIZE_BITS - 1));
 269
 270                 if (bch_keylist_realloc(&op->insert_keys, 0, op->c))
 271                         goto out;
 272
 273                 bio->bi_sector  += sectors;
 274                 bio->bi_size    -= sectors << 9;
 275
 276                 bch_keylist_add(&op->insert_keys,
 277                                 &KEY(op->inode, bio->bi_sector, sectors));
 278         }
 279
 280         op->insert_data_done = true;
 281         bio_put(bio);
 282 out:
 283         continue_at(cl, bch_data_insert_keys, bcache_wq);
 284 }
 285
 286 static void bch_data_insert_error(struct closure *cl)
 287 {
 288         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 289
 290         /*
 291          * Our data write just errored, which means we've got a bunch of keys to
 292          * insert that point to data that wasn't succesfully written.
 293          *
 294          * We don't have to insert those keys but we still have to invalidate
 295          * that region of the cache - so, if we just strip off all the pointers
 296          * from the keys we'll accomplish just that.
 297          */
 298
 299         struct bkey *src = op->insert_keys.keys, *dst = op->insert_keys.keys;
 300
 301         while (src != op->insert_keys.top) {
 302                 struct bkey *n = bkey_next(src);
 303
 304                 SET_KEY_PTRS(src, 0);
 305                 memmove(dst, src, bkey_bytes(src));
 306
 307                 dst = bkey_next(dst);
 308                 src = n;
 309         }
 310
 311         op->insert_keys.top = dst;
 312
 313         bch_data_insert_keys(cl);
 314 }
 315
 316 static void bch_data_insert_endio(struct bio *bio, int error)
 317 {
 318         struct closure *cl = bio->bi_private;
 319         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 320
 321         if (error) {
 322                 /* TODO: We could try to recover from this. */
 323                 if (op->writeback)
 324                         op->error = error;
 325                 else if (!op->replace)
 326                         set_closure_fn(cl, bch_data_insert_error, bcache_wq);
 327                 else
 328                         set_closure_fn(cl, NULL, NULL);
 329         }
 330
 331         bch_bbio_endio(op->c, bio, error, "writing data to cache");
 332 }
 333
 334 static void bch_data_insert_start(struct closure *cl)
 335 {
 336         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 337         struct bio *bio = op->bio, *n;
 338
 339         if (op->bypass)
 340                 return bch_data_invalidate(cl);
 341
 342         if (atomic_sub_return(bio_sectors(bio), &op->c->sectors_to_gc) < 0) {
 343                 set_gc_sectors(op->c);
 344                 wake_up_gc(op->c);
 345         }
 346
 347         /*
 348          * Journal writes are marked REQ_FLUSH; if the original write was a
 349          * flush, it'll wait on the journal write.
 350          */
 351         bio->bi_rw &= ~(REQ_FLUSH|REQ_FUA);
 352
 353         do {
 354                 unsigned i;
 355                 struct bkey *k;
 356                 struct bio_set *split = op->c->bio_split;
 357
 358                 /* 1 for the device pointer and 1 for the chksum */
 359                 if (bch_keylist_realloc(&op->insert_keys,
 360                                         1 + (op->csum ? 1 : 0),
 361                                         op->c))
 362                         continue_at(cl, bch_data_insert_keys, bcache_wq);
 363
 364                 k = op->insert_keys.top;
 365                 bkey_init(k);
 366                 SET_KEY_INODE(k, op->inode);
 367                 SET_KEY_OFFSET(k, bio->bi_sector);
 368
 369                 if (!bch_alloc_sectors(op->c, k, bio_sectors(bio),
 370                                        op->write_point, op->write_prio,
 371                                        op->writeback))
 372                         goto err;
 373
 374                 n = bch_bio_split(bio, KEY_SIZE(k), GFP_NOIO, split);
 375
 376                 n->bi_end_io    = bch_data_insert_endio;
 377                 n->bi_private   = cl;
 378
 379                 if (op->writeback) {
 380                         SET_KEY_DIRTY(k, true);
 381
 382                         for (i = 0; i < KEY_PTRS(k); i++)
 383                                 SET_GC_MARK(PTR_BUCKET(op->c, k, i),
 384                                             GC_MARK_DIRTY);
 385                 }
 386
 387                 SET_KEY_CSUM(k, op->csum);
 388                 if (KEY_CSUM(k))
 389                         bio_csum(n, k);
 390
 391                 trace_bcache_cache_insert(k);
 392                 bch_keylist_push(&op->insert_keys);
 393
 394                 n->bi_rw |= REQ_WRITE;
 395                 bch_submit_bbio(n, op->c, k, 0);
 396         } while (n != bio);
 397
 398         op->insert_data_done = true;
 399         continue_at(cl, bch_data_insert_keys, bcache_wq);
 400 err:
 401         /* bch_alloc_sectors() blocks if s->writeback = true */
 402         BUG_ON(op->writeback);
 403
 404         /*
 405          * But if it's not a writeback write we'd rather just bail out if
 406          * there aren't any buckets ready to write to - it might take awhile and
 407          * we might be starving btree writes for gc or something.
 408          */
 409
 410         if (!op->replace) {
 411                 /*
 412                  * Writethrough write: We can't complete the write until we've
 413                  * updated the index. But we don't want to delay the write while
 414                  * we wait for buckets to be freed up, so just invalidate the
 415                  * rest of the write.
 416                  */
 417                 op->bypass = true;
 418                 return bch_data_invalidate(cl);
 419         } else {
 420                 /*
 421                  * From a cache miss, we can just insert the keys for the data
 422                  * we have written or bail out if we didn't do anything.
 423                  */
 424                 op->insert_data_done = true;
 425                 bio_put(bio);
 426
 427                 if (!bch_keylist_empty(&op->insert_keys))
 428                         continue_at(cl, bch_data_insert_keys, bcache_wq);
 429                 else
 430                         closure_return(cl);
 431         }
 432 }
 433
 434 /**
 435  * bch_data_insert - stick some data in the cache
 436  *
 437  * This is the starting point for any data to end up in a cache device; it could
 438  * be from a normal write, or a writeback write, or a write to a flash only
 439  * volume - it's also used by the moving garbage collector to compact data in
 440  * mostly empty buckets.
 441  *
 442  * It first writes the data to the cache, creating a list of keys to be inserted
 443  * (if the data had to be fragmented there will be multiple keys); after the
 444  * data is written it calls bch_journal, and after the keys have been added to
 445  * the next journal write they're inserted into the btree.
 446  *
 447  * It inserts the data in s->cache_bio; bi_sector is used for the key offset,
 448  * and op->inode is used for the key inode.
 449  *
 450  * If s->bypass is true, instead of inserting the data it invalidates the
 451  * region of the cache represented by s->cache_bio and op->inode.
 452  */
 453 void bch_data_insert(struct closure *cl)
 454 {
 455         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 456
 457         trace_bcache_write(op->bio, op->writeback, op->bypass);
 458
 459         bch_keylist_init(&op->insert_keys);
 460         bio_get(op->bio);
 461         bch_data_insert_start(cl);
 462 }
 463
 464 /* Congested? */
 465
 466 unsigned bch_get_congested(struct cache_set *c)
 467 {
 468         int i;
 469         long rand;
 470
 471         if (!c->congested_read_threshold_us &&
 472             !c->congested_write_threshold_us)
 473                 return 0;
 474
 475         i = (local_clock_us() - c->congested_last_us) / 1024;
 476         if (i < 0)
 477                 return 0;
 478
 479         i += atomic_read(&c->congested);
 480         if (i >= 0)
 481                 return 0;
 482
 483         i += CONGESTED_MAX;
 484
 485         if (i > 0)
 486                 i = fract_exp_two(i, 6);
 487
 488         rand = get_random_int();
 489         i -= bitmap_weight(&rand, BITS_PER_LONG);
 490
 491         return i > 0 ? i : 1;
 492 }
 493
 494 static void add_sequential(struct task_struct *t)
 495 {
 496         ewma_add(t->sequential_io_avg,
 497                  t->sequential_io, 8, 0);
 498
 499         t->sequential_io = 0;
 500 }
 501
 502 static struct hlist_head *iohash(struct cached_dev *dc, uint64_t k)
 503 {
 504         return &dc->io_hash[hash_64(k, RECENT_IO_BITS)];
 505 }
 506
 507 static bool check_should_bypass(struct cached_dev *dc, struct bio *bio)
 508 {
 509         struct cache_set *c = dc->disk.c;
 510         unsigned mode = cache_mode(dc, bio);
 511         unsigned sectors, congested = bch_get_congested(c);
 512         struct task_struct *task = current;
 513         struct io *i;
 514
 515         if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
 516             c->gc_stats.in_use > CUTOFF_CACHE_ADD ||
 517             (bio->bi_rw & REQ_DISCARD))
 518                 goto skip;
 519
 520         if (mode == CACHE_MODE_NONE ||
 521             (mode == CACHE_MODE_WRITEAROUND &&
 522              (bio->bi_rw & REQ_WRITE)))
 523                 goto skip;
 524
 525         if (bio->bi_sector & (c->sb.block_size - 1) ||
 526             bio_sectors(bio) & (c->sb.block_size - 1)) {
 527                 pr_debug("skipping unaligned io");
 528                 goto skip;
 529         }
 530
 531         if (bypass_torture_test(dc)) {
 532                 if ((get_random_int() & 3) == 3)
 533                         goto skip;
 534                 else
 535                         goto rescale;
 536         }
 537
 538         if (!congested && !dc->sequential_cutoff)
 539                 goto rescale;
 540
 541         if (!congested &&
 542             mode == CACHE_MODE_WRITEBACK &&
 543             (bio->bi_rw & REQ_WRITE) &&
 544             (bio->bi_rw & REQ_SYNC))
 545                 goto rescale;
 546
 547         spin_lock(&dc->io_lock);
 548
 549         hlist_for_each_entry(i, iohash(dc, bio->bi_sector), hash)
 550                 if (i->last == bio->bi_sector &&
 551                     time_before(jiffies, i->jiffies))
 552                         goto found;
 553
 554         i = list_first_entry(&dc->io_lru, struct io, lru);
 555
 556         add_sequential(task);
 557         i->sequential = 0;
 558 found:
 559         if (i->sequential + bio->bi_size > i->sequential)
 560                 i->sequential   += bio->bi_size;
 561
 562         i->last                  = bio_end_sector(bio);
 563         i->jiffies               = jiffies + msecs_to_jiffies(5000);
 564         task->sequential_io      = i->sequential;
 565
 566         hlist_del(&i->hash);
 567         hlist_add_head(&i->hash, iohash(dc, i->last));
 568         list_move_tail(&i->lru, &dc->io_lru);
 569
 570         spin_unlock(&dc->io_lock);
 571
 572         sectors = max(task->sequential_io,
 573                       task->sequential_io_avg) >> 9;
 574
 575         if (dc->sequential_cutoff &&
 576             sectors >= dc->sequential_cutoff >> 9) {
 577                 trace_bcache_bypass_sequential(bio);
 578                 goto skip;
 579         }
 580
 581         if (congested && sectors >= congested) {
 582                 trace_bcache_bypass_congested(bio);
 583                 goto skip;
 584         }
 585
 586 rescale:
 587         bch_rescale_priorities(c, bio_sectors(bio));
 588         return false;
 589 skip:
 590         bch_mark_sectors_bypassed(c, dc, bio_sectors(bio));
 591         return true;
 592 }
 593
 594 /* Cache lookup */
 595
 596 struct search {
 597         /* Stack frame for bio_complete */
 598         struct closure          cl;
 599
 600         struct bcache_device    *d;
 601
 602         struct bbio             bio;
 603         struct bio              *orig_bio;
 604         struct bio              *cache_miss;
 605
 606         unsigned                insert_bio_sectors;
 607
 608         unsigned                recoverable:1;
 609         unsigned                unaligned_bvec:1;
 610         unsigned                write:1;
 611         unsigned                read_dirty_data:1;
 612
 613         unsigned long           start_time;
 614
 615         struct btree_op         op;
 616         struct data_insert_op   iop;
 617 };
 618
 619 static void bch_cache_read_endio(struct bio *bio, int error)
 620 {
 621         struct bbio *b = container_of(bio, struct bbio, bio);
 622         struct closure *cl = bio->bi_private;
 623         struct search *s = container_of(cl, struct search, cl);
 624
 625         /*
 626          * If the bucket was reused while our bio was in flight, we might have
 627          * read the wrong data. Set s->error but not error so it doesn't get
 628          * counted against the cache device, but we'll still reread the data
 629          * from the backing device.
 630          */
 631
 632         if (error)
 633                 s->iop.error = error;
 634         else if (ptr_stale(s->iop.c, &b->key, 0)) {
 635                 atomic_long_inc(&s->iop.c->cache_read_races);
 636                 s->iop.error = -EINTR;
 637         }
 638
 639         bch_bbio_endio(s->iop.c, bio, error, "reading from cache");
 640 }
 641
 642 /*
 643  * Read from a single key, handling the initial cache miss if the key starts in
 644  * the middle of the bio
 645  */
 646 static int cache_lookup_fn(struct btree_op *op, struct btree *b, struct bkey *k)
 647 {
 648         struct search *s = container_of(op, struct search, op);
 649         struct bio *n, *bio = &s->bio.bio;
 650         struct bkey *bio_key;
 651         unsigned ptr;
 652
 653         if (bkey_cmp(k, &KEY(s->iop.inode, bio->bi_sector, 0)) <= 0)
 654                 return MAP_CONTINUE;
 655
 656         if (KEY_INODE(k) != s->iop.inode ||
 657             KEY_START(k) > bio->bi_sector) {
 658                 unsigned bio_sectors = bio_sectors(bio);
 659                 unsigned sectors = KEY_INODE(k) == s->iop.inode
 660                         ? min_t(uint64_t, INT_MAX,
 661                                 KEY_START(k) - bio->bi_sector)
 662                         : INT_MAX;
 663
 664                 int ret = s->d->cache_miss(b, s, bio, sectors);
 665                 if (ret != MAP_CONTINUE)
 666                         return ret;
 667
 668                 /* if this was a complete miss we shouldn't get here */
 669                 BUG_ON(bio_sectors <= sectors);
 670         }
 671
 672         if (!KEY_SIZE(k))
 673                 return MAP_CONTINUE;
 674
 675         /* XXX: figure out best pointer - for multiple cache devices */
 676         ptr = 0;
 677
 678         PTR_BUCKET(b->c, k, ptr)->prio = INITIAL_PRIO;
 679
 680         if (KEY_DIRTY(k))
 681                 s->read_dirty_data = true;
 682
 683         n = bch_bio_split(bio, min_t(uint64_t, INT_MAX,
 684                                      KEY_OFFSET(k) - bio->bi_sector),
 685                           GFP_NOIO, s->d->bio_split);
 686
 687         bio_key = &container_of(n, struct bbio, bio)->key;
 688         bch_bkey_copy_single_ptr(bio_key, k, ptr);
 689
 690         bch_cut_front(&KEY(s->iop.inode, n->bi_sector, 0), bio_key);
 691         bch_cut_back(&KEY(s->iop.inode, bio_end_sector(n), 0), bio_key);
 692
 693         n->bi_end_io    = bch_cache_read_endio;
 694         n->bi_private   = &s->cl;
 695
 696         /*
 697          * The bucket we're reading from might be reused while our bio
 698          * is in flight, and we could then end up reading the wrong
 699          * data.
 700          *
 701          * We guard against this by checking (in cache_read_endio()) if
 702          * the pointer is stale again; if so, we treat it as an error
 703          * and reread from the backing device (but we don't pass that
 704          * error up anywhere).
 705          */
 706
 707         __bch_submit_bbio(n, b->c);
 708         return n == bio ? MAP_DONE : MAP_CONTINUE;
 709 }
 710
 711 static void cache_lookup(struct closure *cl)
 712 {
 713         struct search *s = container_of(cl, struct search, iop.cl);
 714         struct bio *bio = &s->bio.bio;
 715
 716         int ret = bch_btree_map_keys(&s->op, s->iop.c,
 717                                      &KEY(s->iop.inode, bio->bi_sector, 0),
 718                                      cache_lookup_fn, MAP_END_KEY);
 719         if (ret == -EAGAIN)
 720                 continue_at(cl, cache_lookup, bcache_wq);
 721
 722         closure_return(cl);
 723 }
 724
 725 /* Common code for the make_request functions */
 726
 727 static void request_endio(struct bio *bio, int error)
 728 {
 729         struct closure *cl = bio->bi_private;
 730
 731         if (error) {
 732                 struct search *s = container_of(cl, struct search, cl);
 733                 s->iop.error = error;
 734                 /* Only cache read errors are recoverable */
 735                 s->recoverable = false;
 736         }
 737
 738         bio_put(bio);
 739         closure_put(cl);
 740 }
 741
 742 static void bio_complete(struct search *s)
 743 {
 744         if (s->orig_bio) {
 745                 int cpu, rw = bio_data_dir(s->orig_bio);
 746                 unsigned long duration = jiffies - s->start_time;
 747
 748                 cpu = part_stat_lock();
 749                 part_round_stats(cpu, &s->d->disk->part0);
 750                 part_stat_add(cpu, &s->d->disk->part0, ticks[rw], duration);
 751                 part_stat_unlock();
 752
 753                 trace_bcache_request_end(s->d, s->orig_bio);
 754                 bio_endio(s->orig_bio, s->iop.error);
 755                 s->orig_bio = NULL;
 756         }
 757 }
 758
 759 static void do_bio_hook(struct search *s)
 760 {
 761         struct bio *bio = &s->bio.bio;
 762         memcpy(bio, s->orig_bio, sizeof(struct bio));
 763
 764         bio->bi_end_io          = request_endio;
 765         bio->bi_private         = &s->cl;
 766         atomic_set(&bio->bi_cnt, 3);
 767 }
 768
 769 static void search_free(struct closure *cl)
 770 {
 771         struct search *s = container_of(cl, struct search, cl);
 772         bio_complete(s);
 773
 774         if (s->iop.bio)
 775                 bio_put(s->iop.bio);
 776
 777         if (s->unaligned_bvec)
 778                 mempool_free(s->bio.bio.bi_io_vec, s->d->unaligned_bvec);
 779
 780         closure_debug_destroy(cl);
 781         mempool_free(s, s->d->c->search);
 782 }
 783
 784 static struct search *search_alloc(struct bio *bio, struct bcache_device *d)
 785 {
 786         struct search *s;
 787         struct bio_vec *bv;
 788
 789         s = mempool_alloc(d->c->search, GFP_NOIO);
 790         memset(s, 0, offsetof(struct search, iop.insert_keys));
 791
 792         __closure_init(&s->cl, NULL);
 793
 794         s->iop.inode            = d->id;
 795         s->iop.c                = d->c;
 796         s->d                    = d;
 797         s->op.lock              = -1;
 798         s->iop.write_point      = hash_long((unsigned long) current, 16);
 799         s->orig_bio             = bio;
 800         s->write                = (bio->bi_rw & REQ_WRITE) != 0;
 801         s->iop.flush_journal    = (bio->bi_rw & (REQ_FLUSH|REQ_FUA)) != 0;
 802         s->recoverable          = 1;
 803         s->start_time           = jiffies;
 804         do_bio_hook(s);
 805
 806         if (bio->bi_size != bio_segments(bio) * PAGE_SIZE) {
 807                 bv = mempool_alloc(d->unaligned_bvec, GFP_NOIO);
 808                 memcpy(bv, bio_iovec(bio),
 809                        sizeof(struct bio_vec) * bio_segments(bio));
 810
 811                 s->bio.bio.bi_io_vec    = bv;
 812                 s->unaligned_bvec       = 1;
 813         }
 814
 815         return s;
 816 }
 817
 818 /* Cached devices */
 819
 820 static void cached_dev_bio_complete(struct closure *cl)
 821 {
 822         struct search *s = container_of(cl, struct search, cl);
 823         struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 824
 825         search_free(cl);
 826         cached_dev_put(dc);
 827 }
 828
 829 /* Process reads */
 830
 831 static void cached_dev_cache_miss_done(struct closure *cl)
 832 {
 833         struct search *s = container_of(cl, struct search, cl);
 834
 835         if (s->iop.replace_collision)
 836                 bch_mark_cache_miss_collision(s->iop.c, s->d);
 837
 838         if (s->iop.bio) {
 839                 int i;
 840                 struct bio_vec *bv;
 841
 842                 bio_for_each_segment_all(bv, s->iop.bio, i)
 843                         __free_page(bv->bv_page);
 844         }
 845
 846         cached_dev_bio_complete(cl);
 847 }
 848
 849 static void cached_dev_read_error(struct closure *cl)
 850 {
 851         struct search *s = container_of(cl, struct search, cl);
 852         struct bio *bio = &s->bio.bio;
 853         struct bio_vec *bv;
 854         int i;
 855
 856         if (s->recoverable) {
 857                 /* Retry from the backing device: */
 858                 trace_bcache_read_retry(s->orig_bio);
 859
 860                 s->iop.error = 0;
 861                 bv = s->bio.bio.bi_io_vec;
 862                 do_bio_hook(s);
 863                 s->bio.bio.bi_io_vec = bv;
 864
 865                 if (!s->unaligned_bvec)
 866                         bio_for_each_segment(bv, s->orig_bio, i)
 867                                 bv->bv_offset = 0, bv->bv_len = PAGE_SIZE;
 868                 else
 869                         memcpy(s->bio.bio.bi_io_vec,
 870                                bio_iovec(s->orig_bio),
 871                                sizeof(struct bio_vec) *
 872                                bio_segments(s->orig_bio));
 873
 874                 /* XXX: invalidate cache */
 875
 876                 closure_bio_submit(bio, cl, s->d);
 877         }
 878
 879         continue_at(cl, cached_dev_cache_miss_done, NULL);
 880 }
 881
 882 static void cached_dev_read_done(struct closure *cl)
 883 {
 884         struct search *s = container_of(cl, struct search, cl);
 885         struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 886
 887         /*
 888          * We had a cache miss; cache_bio now contains data ready to be inserted
 889          * into the cache.
 890          *
 891          * First, we copy the data we just read from cache_bio's bounce buffers
 892          * to the buffers the original bio pointed to:
 893          */
 894
 895         if (s->iop.bio) {
 896                 bio_reset(s->iop.bio);
 897                 s->iop.bio->bi_sector = s->cache_miss->bi_sector;
 898                 s->iop.bio->bi_bdev = s->cache_miss->bi_bdev;
 899                 s->iop.bio->bi_size = s->insert_bio_sectors << 9;
 900                 bch_bio_map(s->iop.bio, NULL);
 901
 902                 bio_copy_data(s->cache_miss, s->iop.bio);
 903
 904                 bio_put(s->cache_miss);
 905                 s->cache_miss = NULL;
 906         }
 907
 908         if (verify(dc, &s->bio.bio) && s->recoverable &&
 909             !s->unaligned_bvec && !s->read_dirty_data)
 910                 bch_data_verify(dc, s->orig_bio);
 911
 912         bio_complete(s);
 913
 914         if (s->iop.bio &&
 915             !test_bit(CACHE_SET_STOPPING, &s->iop.c->flags)) {
 916                 BUG_ON(!s->iop.replace);
 917                 closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
 918         }
 919
 920         continue_at(cl, cached_dev_cache_miss_done, NULL);
 921 }
 922
 923 static void cached_dev_read_done_bh(struct closure *cl)
 924 {
 925         struct search *s = container_of(cl, struct search, cl);
 926         struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 927
 928         bch_mark_cache_accounting(s->iop.c, s->d,
 929                                   !s->cache_miss, s->iop.bypass);
 930         trace_bcache_read(s->orig_bio, !s->cache_miss, s->iop.bypass);
 931
 932         if (s->iop.error)
 933                 continue_at_nobarrier(cl, cached_dev_read_error, bcache_wq);
 934         else if (s->iop.bio || verify(dc, &s->bio.bio))
 935                 continue_at_nobarrier(cl, cached_dev_read_done, bcache_wq);
 936         else
 937                 continue_at_nobarrier(cl, cached_dev_bio_complete, NULL);
 938 }
 939
 940 static int cached_dev_cache_miss(struct btree *b, struct search *s,
 941                                  struct bio *bio, unsigned sectors)
 942 {
 943         int ret = MAP_CONTINUE;
 944         unsigned reada = 0;
 945         struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 946         struct bio *miss, *cache_bio;
 947
 948         if (s->cache_miss || s->iop.bypass) {
 949                 miss = bch_bio_split(bio, sectors, GFP_NOIO, s->d->bio_split);
 950                 ret = miss == bio ? MAP_DONE : MAP_CONTINUE;
 951                 goto out_submit;
 952         }
 953
 954         if (!(bio->bi_rw & REQ_RAHEAD) &&
 955             !(bio->bi_rw & REQ_META) &&
 956             s->iop.c->gc_stats.in_use < CUTOFF_CACHE_READA)
 957                 reada = min_t(sector_t, dc->readahead >> 9,
 958                               bdev_sectors(bio->bi_bdev) - bio_end_sector(bio));
 959
 960         s->insert_bio_sectors = min(sectors, bio_sectors(bio) + reada);
 961
 962         s->iop.replace_key = KEY(s->iop.inode,
 963                                  bio->bi_sector + s->insert_bio_sectors,
 964                                  s->insert_bio_sectors);
 965
 966         ret = bch_btree_insert_check_key(b, &s->op, &s->iop.replace_key);
 967         if (ret)
 968                 return ret;
 969
 970         s->iop.replace = true;
 971
 972         miss = bch_bio_split(bio, sectors, GFP_NOIO, s->d->bio_split);
 973
 974         /* btree_search_recurse()'s btree iterator is no good anymore */
 975         ret = miss == bio ? MAP_DONE : -EINTR;
 976
 977         cache_bio = bio_alloc_bioset(GFP_NOWAIT,
 978                         DIV_ROUND_UP(s->insert_bio_sectors, PAGE_SECTORS),
 979                         dc->disk.bio_split);
 980         if (!cache_bio)
 981                 goto out_submit;
 982
 983         cache_bio->bi_sector    = miss->bi_sector;
 984         cache_bio->bi_bdev      = miss->bi_bdev;
 985         cache_bio->bi_size      = s->insert_bio_sectors << 9;
 986
 987         cache_bio->bi_end_io    = request_endio;
 988         cache_bio->bi_private   = &s->cl;
 989
 990         bch_bio_map(cache_bio, NULL);
 991         if (bio_alloc_pages(cache_bio, __GFP_NOWARN|GFP_NOIO))
 992                 goto out_put;
 993
 994         if (reada)
 995                 bch_mark_cache_readahead(s->iop.c, s->d);
 996
 997         s->cache_miss   = miss;
 998         s->iop.bio      = cache_bio;
 999         bio_get(cache_bio);
1000         closure_bio_submit(cache_bio, &s->cl, s->d);
1001
1002         return ret;
1003 out_put:
1004         bio_put(cache_bio);
1005 out_submit:
1006         miss->bi_end_io         = request_endio;
1007         miss->bi_private        = &s->cl;
1008         closure_bio_submit(miss, &s->cl, s->d);
1009         return ret;
1010 }
1011
1012 static void cached_dev_read(struct cached_dev *dc, struct search *s)
1013 {
1014         struct closure *cl = &s->cl;
1015
1016         closure_call(&s->iop.cl, cache_lookup, NULL, cl);
1017         continue_at(cl, cached_dev_read_done_bh, NULL);
1018 }
1019
1020 /* Process writes */
1021
1022 static void cached_dev_write_complete(struct closure *cl)
1023 {
1024         struct search *s = container_of(cl, struct search, cl);
1025         struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
1026
1027         up_read_non_owner(&dc->writeback_lock);
1028         cached_dev_bio_complete(cl);
1029 }
1030
1031 static void cached_dev_write(struct cached_dev *dc, struct search *s)
1032 {
1033         struct closure *cl = &s->cl;
1034         struct bio *bio = &s->bio.bio;
1035         struct bkey start = KEY(dc->disk.id, bio->bi_sector, 0);
1036         struct bkey end = KEY(dc->disk.id, bio_end_sector(bio), 0);
1037
1038         bch_keybuf_check_overlapping(&s->iop.c->moving_gc_keys, &start, &end);
1039
1040         down_read_non_owner(&dc->writeback_lock);
1041         if (bch_keybuf_check_overlapping(&dc->writeback_keys, &start, &end)) {
1042                 /*
1043                  * We overlap with some dirty data undergoing background
1044                  * writeback, force this write to writeback
1045                  */
1046                 s->iop.bypass = false;
1047                 s->iop.writeback = true;
1048         }
1049
1050         /*
1051          * Discards aren't _required_ to do anything, so skipping if
1052          * check_overlapping returned true is ok
1053          *
1054          * But check_overlapping drops dirty keys for which io hasn't started,
1055          * so we still want to call it.
1056          */
1057         if (bio->bi_rw & REQ_DISCARD)
1058                 s->iop.bypass = true;
1059
1060         if (should_writeback(dc, s->orig_bio,
1061                              cache_mode(dc, bio),
1062                              s->iop.bypass)) {
1063                 s->iop.bypass = false;
1064                 s->iop.writeback = true;
1065         }
1066
1067         if (s->iop.bypass) {
1068                 s->iop.bio = s->orig_bio;
1069                 bio_get(s->iop.bio);
1070
1071                 if (!(bio->bi_rw & REQ_DISCARD) ||
1072                     blk_queue_discard(bdev_get_queue(dc->bdev)))
1073                         closure_bio_submit(bio, cl, s->d);
1074         } else if (s->iop.writeback) {
1075                 bch_writeback_add(dc);
1076                 s->iop.bio = bio;
1077
1078                 if (bio->bi_rw & REQ_FLUSH) {
1079                         /* Also need to send a flush to the backing device */
1080                         struct bio *flush = bio_alloc_bioset(GFP_NOIO, 0,
1081                                                              dc->disk.bio_split);
1082
1083                         flush->bi_rw    = WRITE_FLUSH;
1084                         flush->bi_bdev  = bio->bi_bdev;
1085                         flush->bi_end_io = request_endio;
1086                         flush->bi_private = cl;
1087
1088                         closure_bio_submit(flush, cl, s->d);
1089                 }
1090         } else {
1091                 s->iop.bio = bio_clone_bioset(bio, GFP_NOIO,
1092                                               dc->disk.bio_split);
1093
1094                 closure_bio_submit(bio, cl, s->d);
1095         }
1096
1097         closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
1098         continue_at(cl, cached_dev_write_complete, NULL);
1099 }
1100
1101 static void cached_dev_nodata(struct closure *cl)
1102 {
1103         struct search *s = container_of(cl, struct search, cl);
1104         struct bio *bio = &s->bio.bio;
1105
1106         if (s->iop.flush_journal)
1107                 bch_journal_meta(s->iop.c, cl);
1108
1109         /* If it's a flush, we send the flush to the backing device too */
1110         closure_bio_submit(bio, cl, s->d);
1111
1112         continue_at(cl, cached_dev_bio_complete, NULL);
1113 }
1114
1115 /* Cached devices - read & write stuff */
1116
1117 static void cached_dev_make_request(struct request_queue *q, struct bio *bio)
1118 {
1119         struct search *s;
1120         struct bcache_device *d = bio->bi_bdev->bd_disk->private_data;
1121         struct cached_dev *dc = container_of(d, struct cached_dev, disk);
1122         int cpu, rw = bio_data_dir(bio);
1123
1124         cpu = part_stat_lock();
1125         part_stat_inc(cpu, &d->disk->part0, ios[rw]);
1126         part_stat_add(cpu, &d->disk->part0, sectors[rw], bio_sectors(bio));
1127         part_stat_unlock();
1128
1129         bio->bi_bdev = dc->bdev;
1130         bio->bi_sector += dc->sb.data_offset;
1131
1132         if (cached_dev_get(dc)) {
1133                 s = search_alloc(bio, d);
1134                 trace_bcache_request_start(s->d, bio);
1135
1136                 if (!bio->bi_size) {
1137                         /*
1138                          * can't call bch_journal_meta from under
1139                          * generic_make_request
1140                          */
1141                         continue_at_nobarrier(&s->cl,
1142                                               cached_dev_nodata,
1143                                               bcache_wq);
1144                 } else {
1145                         s->iop.bypass = check_should_bypass(dc, bio);
1146
1147                         if (rw)
1148                                 cached_dev_write(dc, s);
1149                         else
1150                                 cached_dev_read(dc, s);
1151                 }
1152         } else {
1153                 if ((bio->bi_rw & REQ_DISCARD) &&
1154                     !blk_queue_discard(bdev_get_queue(dc->bdev)))
1155                         bio_endio(bio, 0);
1156                 else
1157                         bch_generic_make_request(bio, &d->bio_split_hook);
1158         }
1159 }
1160
1161 static int cached_dev_ioctl(struct bcache_device *d, fmode_t mode,
1162                             unsigned int cmd, unsigned long arg)
1163 {
1164         struct cached_dev *dc = container_of(d, struct cached_dev, disk);
1165         return __blkdev_driver_ioctl(dc->bdev, mode, cmd, arg);
1166 }
1167
1168 static int cached_dev_congested(void *data, int bits)
1169 {
1170         struct bcache_device *d = data;
1171         struct cached_dev *dc = container_of(d, struct cached_dev, disk);
1172         struct request_queue *q = bdev_get_queue(dc->bdev);
1173         int ret = 0;
1174
1175         if (bdi_congested(&q->backing_dev_info, bits))
1176                 return 1;
1177
1178         if (cached_dev_get(dc)) {
1179                 unsigned i;
1180                 struct cache *ca;
1181
1182                 for_each_cache(ca, d->c, i) {
1183                         q = bdev_get_queue(ca->bdev);
1184                         ret |= bdi_congested(&q->backing_dev_info, bits);
1185                 }
1186
1187                 cached_dev_put(dc);
1188         }
1189
1190         return ret;
1191 }
1192
1193 void bch_cached_dev_request_init(struct cached_dev *dc)
1194 {
1195         struct gendisk *g = dc->disk.disk;
1196
1197         g->queue->make_request_fn               = cached_dev_make_request;
1198         g->queue->backing_dev_info.congested_fn = cached_dev_congested;
1199         dc->disk.cache_miss                     = cached_dev_cache_miss;
1200         dc->disk.ioctl                          = cached_dev_ioctl;
1201 }
1202
1203 /* Flash backed devices */
1204
1205 static int flash_dev_cache_miss(struct btree *b, struct search *s,
1206                                 struct bio *bio, unsigned sectors)
1207 {
1208         struct bio_vec *bv;
1209         int i;
1210
1211         /* Zero fill bio */
1212
1213         bio_for_each_segment(bv, bio, i) {
1214                 unsigned j = min(bv->bv_len >> 9, sectors);
1215
1216                 void *p = kmap(bv->bv_page);
1217                 memset(p + bv->bv_offset, 0, j << 9);
1218                 kunmap(bv->bv_page);
1219
1220                 sectors -= j;
1221         }
1222
1223         bio_advance(bio, min(sectors << 9, bio->bi_size));
1224
1225         if (!bio->bi_size)
1226                 return MAP_DONE;
1227
1228         return MAP_CONTINUE;
1229 }
1230
1231 static void flash_dev_nodata(struct closure *cl)
1232 {
1233         struct search *s = container_of(cl, struct search, cl);
1234
1235         if (s->iop.flush_journal)
1236                 bch_journal_meta(s->iop.c, cl);
1237
1238         continue_at(cl, search_free, NULL);
1239 }
1240
1241 static void flash_dev_make_request(struct request_queue *q, struct bio *bio)
1242 {
1243         struct search *s;
1244         struct closure *cl;
1245         struct bcache_device *d = bio->bi_bdev->bd_disk->private_data;
1246         int cpu, rw = bio_data_dir(bio);
1247
1248         cpu = part_stat_lock();
1249         part_stat_inc(cpu, &d->disk->part0, ios[rw]);
1250         part_stat_add(cpu, &d->disk->part0, sectors[rw], bio_sectors(bio));
1251         part_stat_unlock();
1252
1253         s = search_alloc(bio, d);
1254         cl = &s->cl;
1255         bio = &s->bio.bio;
1256
1257         trace_bcache_request_start(s->d, bio);
1258
1259         if (!bio->bi_size) {
1260                 /*
1261                  * can't call bch_journal_meta from under
1262                  * generic_make_request
1263                  */
1264                 continue_at_nobarrier(&s->cl,
1265                                       flash_dev_nodata,
1266                                       bcache_wq);
1267         } else if (rw) {
1268                 bch_keybuf_check_overlapping(&s->iop.c->moving_gc_keys,
1269                                         &KEY(d->id, bio->bi_sector, 0),
1270                                         &KEY(d->id, bio_end_sector(bio), 0));
1271
1272                 s->iop.bypass           = (bio->bi_rw & REQ_DISCARD) != 0;
1273                 s->iop.writeback        = true;
1274                 s->iop.bio              = bio;
1275
1276                 closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
1277         } else {
1278                 closure_call(&s->iop.cl, cache_lookup, NULL, cl);
1279         }
1280
1281         continue_at(cl, search_free, NULL);
1282 }
1283
1284 static int flash_dev_ioctl(struct bcache_device *d, fmode_t mode,
1285                            unsigned int cmd, unsigned long arg)
1286 {
1287         return -ENOTTY;
1288 }
1289
1290 static int flash_dev_congested(void *data, int bits)
1291 {
1292         struct bcache_device *d = data;
1293         struct request_queue *q;
1294         struct cache *ca;
1295         unsigned i;
1296         int ret = 0;
1297
1298         for_each_cache(ca, d->c, i) {
1299                 q = bdev_get_queue(ca->bdev);
1300                 ret |= bdi_congested(&q->backing_dev_info, bits);
1301         }
1302
1303         return ret;
1304 }
1305
1306 void bch_flash_dev_request_init(struct bcache_device *d)
1307 {
1308         struct gendisk *g = d->disk;
1309
1310         g->queue->make_request_fn               = flash_dev_make_request;
1311         g->queue->backing_dev_info.congested_fn = flash_dev_congested;
1312         d->cache_miss                           = flash_dev_cache_miss;
1313         d->ioctl                                = flash_dev_ioctl;
1314 }
1315
1316 void bch_request_exit(void)
1317 {
1318 #ifdef CONFIG_CGROUP_BCACHE
1319         cgroup_unload_subsys(&bcache_subsys);
1320 #endif
1321         if (bch_search_cache)
1322                 kmem_cache_destroy(bch_search_cache);
1323 }
1324
1325 int __init bch_request_init(void)
1326 {
1327         bch_search_cache = KMEM_CACHE(search, 0);
1328         if (!bch_search_cache)
1329                 return -ENOMEM;
1330
1331 #ifdef CONFIG_CGROUP_BCACHE
1332         cgroup_load_subsys(&bcache_subsys);
1333         init_bch_cgroup(&bcache_default_cgroup);
1334
1335         cgroup_add_cftypes(&bcache_subsys, bch_files);
1336 #endif
1337         return 0;
1338 }