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         struct bvec_iter iter;
 203         uint64_t csum = 0;
 204
 205         bio_for_each_segment(bv, bio, iter) {
 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 int bch_keylist_realloc(struct keylist *l, unsigned u64s,
 259                                struct cache_set *c)
 260 {
 261         size_t oldsize = bch_keylist_nkeys(l);
 262         size_t newsize = oldsize + u64s;
 263
 264         /*
 265          * The journalling code doesn't handle the case where the keys to insert
 266          * is bigger than an empty write: If we just return -ENOMEM here,
 267          * bio_insert() and bio_invalidate() will insert the keys created so far
 268          * and finish the rest when the keylist is empty.
 269          */
 270         if (newsize * sizeof(uint64_t) > block_bytes(c) - sizeof(struct jset))
 271                 return -ENOMEM;
 272
 273         return __bch_keylist_realloc(l, u64s);
 274 }
 275
 276 static void bch_data_invalidate(struct closure *cl)
 277 {
 278         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 279         struct bio *bio = op->bio;
 280
 281         pr_debug("invalidating %i sectors from %llu",
 282                  bio_sectors(bio), (uint64_t) bio->bi_iter.bi_sector);
 283
 284         while (bio_sectors(bio)) {
 285                 unsigned sectors = min(bio_sectors(bio),
 286                                        1U << (KEY_SIZE_BITS - 1));
 287
 288                 if (bch_keylist_realloc(&op->insert_keys, 2, op->c))
 289                         goto out;
 290
 291                 bio->bi_iter.bi_sector  += sectors;
 292                 bio->bi_iter.bi_size    -= sectors << 9;
 293
 294                 bch_keylist_add(&op->insert_keys,
 295                                 &KEY(op->inode, bio->bi_iter.bi_sector, sectors));
 296         }
 297
 298         op->insert_data_done = true;
 299         bio_put(bio);
 300 out:
 301         continue_at(cl, bch_data_insert_keys, bcache_wq);
 302 }
 303
 304 static void bch_data_insert_error(struct closure *cl)
 305 {
 306         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 307
 308         /*
 309          * Our data write just errored, which means we've got a bunch of keys to
 310          * insert that point to data that wasn't succesfully written.
 311          *
 312          * We don't have to insert those keys but we still have to invalidate
 313          * that region of the cache - so, if we just strip off all the pointers
 314          * from the keys we'll accomplish just that.
 315          */
 316
 317         struct bkey *src = op->insert_keys.keys, *dst = op->insert_keys.keys;
 318
 319         while (src != op->insert_keys.top) {
 320                 struct bkey *n = bkey_next(src);
 321
 322                 SET_KEY_PTRS(src, 0);
 323                 memmove(dst, src, bkey_bytes(src));
 324
 325                 dst = bkey_next(dst);
 326                 src = n;
 327         }
 328
 329         op->insert_keys.top = dst;
 330
 331         bch_data_insert_keys(cl);
 332 }
 333
 334 static void bch_data_insert_endio(struct bio *bio, int error)
 335 {
 336         struct closure *cl = bio->bi_private;
 337         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 338
 339         if (error) {
 340                 /* TODO: We could try to recover from this. */
 341                 if (op->writeback)
 342                         op->error = error;
 343                 else if (!op->replace)
 344                         set_closure_fn(cl, bch_data_insert_error, bcache_wq);
 345                 else
 346                         set_closure_fn(cl, NULL, NULL);
 347         }
 348
 349         bch_bbio_endio(op->c, bio, error, "writing data to cache");
 350 }
 351
 352 static void bch_data_insert_start(struct closure *cl)
 353 {
 354         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 355         struct bio *bio = op->bio, *n;
 356
 357         if (op->bypass)
 358                 return bch_data_invalidate(cl);
 359
 360         if (atomic_sub_return(bio_sectors(bio), &op->c->sectors_to_gc) < 0) {
 361                 set_gc_sectors(op->c);
 362                 wake_up_gc(op->c);
 363         }
 364
 365         /*
 366          * Journal writes are marked REQ_FLUSH; if the original write was a
 367          * flush, it'll wait on the journal write.
 368          */
 369         bio->bi_rw &= ~(REQ_FLUSH|REQ_FUA);
 370
 371         do {
 372                 unsigned i;
 373                 struct bkey *k;
 374                 struct bio_set *split = op->c->bio_split;
 375
 376                 /* 1 for the device pointer and 1 for the chksum */
 377                 if (bch_keylist_realloc(&op->insert_keys,
 378                                         3 + (op->csum ? 1 : 0),
 379                                         op->c))
 380                         continue_at(cl, bch_data_insert_keys, bcache_wq);
 381
 382                 k = op->insert_keys.top;
 383                 bkey_init(k);
 384                 SET_KEY_INODE(k, op->inode);
 385                 SET_KEY_OFFSET(k, bio->bi_iter.bi_sector);
 386
 387                 if (!bch_alloc_sectors(op->c, k, bio_sectors(bio),
 388                                        op->write_point, op->write_prio,
 389                                        op->writeback))
 390                         goto err;
 391
 392                 n = bio_next_split(bio, KEY_SIZE(k), GFP_NOIO, split);
 393
 394                 n->bi_end_io    = bch_data_insert_endio;
 395                 n->bi_private   = cl;
 396
 397                 if (op->writeback) {
 398                         SET_KEY_DIRTY(k, true);
 399
 400                         for (i = 0; i < KEY_PTRS(k); i++)
 401                                 SET_GC_MARK(PTR_BUCKET(op->c, k, i),
 402                                             GC_MARK_DIRTY);
 403                 }
 404
 405                 SET_KEY_CSUM(k, op->csum);
 406                 if (KEY_CSUM(k))
 407                         bio_csum(n, k);
 408
 409                 trace_bcache_cache_insert(k);
 410                 bch_keylist_push(&op->insert_keys);
 411
 412                 n->bi_rw |= REQ_WRITE;
 413                 bch_submit_bbio(n, op->c, k, 0);
 414         } while (n != bio);
 415
 416         op->insert_data_done = true;
 417         continue_at(cl, bch_data_insert_keys, bcache_wq);
 418 err:
 419         /* bch_alloc_sectors() blocks if s->writeback = true */
 420         BUG_ON(op->writeback);
 421
 422         /*
 423          * But if it's not a writeback write we'd rather just bail out if
 424          * there aren't any buckets ready to write to - it might take awhile and
 425          * we might be starving btree writes for gc or something.
 426          */
 427
 428         if (!op->replace) {
 429                 /*
 430                  * Writethrough write: We can't complete the write until we've
 431                  * updated the index. But we don't want to delay the write while
 432                  * we wait for buckets to be freed up, so just invalidate the
 433                  * rest of the write.
 434                  */
 435                 op->bypass = true;
 436                 return bch_data_invalidate(cl);
 437         } else {
 438                 /*
 439                  * From a cache miss, we can just insert the keys for the data
 440                  * we have written or bail out if we didn't do anything.
 441                  */
 442                 op->insert_data_done = true;
 443                 bio_put(bio);
 444
 445                 if (!bch_keylist_empty(&op->insert_keys))
 446                         continue_at(cl, bch_data_insert_keys, bcache_wq);
 447                 else
 448                         closure_return(cl);
 449         }
 450 }
 451
 452 /**
 453  * bch_data_insert - stick some data in the cache
 454  *
 455  * This is the starting point for any data to end up in a cache device; it could
 456  * be from a normal write, or a writeback write, or a write to a flash only
 457  * volume - it's also used by the moving garbage collector to compact data in
 458  * mostly empty buckets.
 459  *
 460  * It first writes the data to the cache, creating a list of keys to be inserted
 461  * (if the data had to be fragmented there will be multiple keys); after the
 462  * data is written it calls bch_journal, and after the keys have been added to
 463  * the next journal write they're inserted into the btree.
 464  *
 465  * It inserts the data in s->cache_bio; bi_sector is used for the key offset,
 466  * and op->inode is used for the key inode.
 467  *
 468  * If s->bypass is true, instead of inserting the data it invalidates the
 469  * region of the cache represented by s->cache_bio and op->inode.
 470  */
 471 void bch_data_insert(struct closure *cl)
 472 {
 473         struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 474
 475         trace_bcache_write(op->bio, op->writeback, op->bypass);
 476
 477         bch_keylist_init(&op->insert_keys);
 478         bio_get(op->bio);
 479         bch_data_insert_start(cl);
 480 }
 481
 482 /* Congested? */
 483
 484 unsigned bch_get_congested(struct cache_set *c)
 485 {
 486         int i;
 487         long rand;
 488
 489         if (!c->congested_read_threshold_us &&
 490             !c->congested_write_threshold_us)
 491                 return 0;
 492
 493         i = (local_clock_us() - c->congested_last_us) / 1024;
 494         if (i < 0)
 495                 return 0;
 496
 497         i += atomic_read(&c->congested);
 498         if (i >= 0)
 499                 return 0;
 500
 501         i += CONGESTED_MAX;
 502
 503         if (i > 0)
 504                 i = fract_exp_two(i, 6);
 505
 506         rand = get_random_int();
 507         i -= bitmap_weight(&rand, BITS_PER_LONG);
 508
 509         return i > 0 ? i : 1;
 510 }
 511
 512 static void add_sequential(struct task_struct *t)
 513 {
 514         ewma_add(t->sequential_io_avg,
 515                  t->sequential_io, 8, 0);
 516
 517         t->sequential_io = 0;
 518 }
 519
 520 static struct hlist_head *iohash(struct cached_dev *dc, uint64_t k)
 521 {
 522         return &dc->io_hash[hash_64(k, RECENT_IO_BITS)];
 523 }
 524
 525 static bool check_should_bypass(struct cached_dev *dc, struct bio *bio)
 526 {
 527         struct cache_set *c = dc->disk.c;
 528         unsigned mode = cache_mode(dc, bio);
 529         unsigned sectors, congested = bch_get_congested(c);
 530         struct task_struct *task = current;
 531         struct io *i;
 532
 533         if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
 534             c->gc_stats.in_use > CUTOFF_CACHE_ADD ||
 535             (bio->bi_rw & REQ_DISCARD))
 536                 goto skip;
 537
 538         if (mode == CACHE_MODE_NONE ||
 539             (mode == CACHE_MODE_WRITEAROUND &&
 540              (bio->bi_rw & REQ_WRITE)))
 541                 goto skip;
 542
 543         if (bio->bi_iter.bi_sector & (c->sb.block_size - 1) ||
 544             bio_sectors(bio) & (c->sb.block_size - 1)) {
 545                 pr_debug("skipping unaligned io");
 546                 goto skip;
 547         }
 548
 549         if (bypass_torture_test(dc)) {
 550                 if ((get_random_int() & 3) == 3)
 551                         goto skip;
 552                 else
 553                         goto rescale;
 554         }
 555
 556         if (!congested && !dc->sequential_cutoff)
 557                 goto rescale;
 558
 559         if (!congested &&
 560             mode == CACHE_MODE_WRITEBACK &&
 561             (bio->bi_rw & REQ_WRITE) &&
 562             (bio->bi_rw & REQ_SYNC))
 563                 goto rescale;
 564
 565         spin_lock(&dc->io_lock);
 566
 567         hlist_for_each_entry(i, iohash(dc, bio->bi_iter.bi_sector), hash)
 568                 if (i->last == bio->bi_iter.bi_sector &&
 569                     time_before(jiffies, i->jiffies))
 570                         goto found;
 571
 572         i = list_first_entry(&dc->io_lru, struct io, lru);
 573
 574         add_sequential(task);
 575         i->sequential = 0;
 576 found:
 577         if (i->sequential + bio->bi_iter.bi_size > i->sequential)
 578                 i->sequential   += bio->bi_iter.bi_size;
 579
 580         i->last                  = bio_end_sector(bio);
 581         i->jiffies               = jiffies + msecs_to_jiffies(5000);
 582         task->sequential_io      = i->sequential;
 583
 584         hlist_del(&i->hash);
 585         hlist_add_head(&i->hash, iohash(dc, i->last));
 586         list_move_tail(&i->lru, &dc->io_lru);
 587
 588         spin_unlock(&dc->io_lock);
 589
 590         sectors = max(task->sequential_io,
 591                       task->sequential_io_avg) >> 9;
 592
 593         if (dc->sequential_cutoff &&
 594             sectors >= dc->sequential_cutoff >> 9) {
 595                 trace_bcache_bypass_sequential(bio);
 596                 goto skip;
 597         }
 598
 599         if (congested && sectors >= congested) {
 600                 trace_bcache_bypass_congested(bio);
 601                 goto skip;
 602         }
 603
 604 rescale:
 605         bch_rescale_priorities(c, bio_sectors(bio));
 606         return false;
 607 skip:
 608         bch_mark_sectors_bypassed(c, dc, bio_sectors(bio));
 609         return true;
 610 }
 611
 612 /* Cache lookup */
 613
 614 struct search {
 615         /* Stack frame for bio_complete */
 616         struct closure          cl;
 617
 618         struct bbio             bio;
 619         struct bio              *orig_bio;
 620         struct bio              *cache_miss;
 621         struct bcache_device    *d;
 622
 623         unsigned                insert_bio_sectors;
 624         unsigned                recoverable:1;
 625         unsigned                write:1;
 626         unsigned                read_dirty_data:1;
 627
 628         unsigned long           start_time;
 629
 630         struct btree_op         op;
 631         struct data_insert_op   iop;
 632 };
 633
 634 static void bch_cache_read_endio(struct bio *bio, int error)
 635 {
 636         struct bbio *b = container_of(bio, struct bbio, bio);
 637         struct closure *cl = bio->bi_private;
 638         struct search *s = container_of(cl, struct search, cl);
 639
 640         /*
 641          * If the bucket was reused while our bio was in flight, we might have
 642          * read the wrong data. Set s->error but not error so it doesn't get
 643          * counted against the cache device, but we'll still reread the data
 644          * from the backing device.
 645          */
 646
 647         if (error)
 648                 s->iop.error = error;
 649         else if (!KEY_DIRTY(&b->key) &&
 650                  ptr_stale(s->iop.c, &b->key, 0)) {
 651                 atomic_long_inc(&s->iop.c->cache_read_races);
 652                 s->iop.error = -EINTR;
 653         }
 654
 655         bch_bbio_endio(s->iop.c, bio, error, "reading from cache");
 656 }
 657
 658 /*
 659  * Read from a single key, handling the initial cache miss if the key starts in
 660  * the middle of the bio
 661  */
 662 static int cache_lookup_fn(struct btree_op *op, struct btree *b, struct bkey *k)
 663 {
 664         struct search *s = container_of(op, struct search, op);
 665         struct bio *n, *bio = &s->bio.bio;
 666         struct bkey *bio_key;
 667         unsigned ptr;
 668
 669         if (bkey_cmp(k, &KEY(s->iop.inode, bio->bi_iter.bi_sector, 0)) <= 0)
 670                 return MAP_CONTINUE;
 671
 672         if (KEY_INODE(k) != s->iop.inode ||
 673             KEY_START(k) > bio->bi_iter.bi_sector) {
 674                 unsigned bio_sectors = bio_sectors(bio);
 675                 unsigned sectors = KEY_INODE(k) == s->iop.inode
 676                         ? min_t(uint64_t, INT_MAX,
 677                                 KEY_START(k) - bio->bi_iter.bi_sector)
 678                         : INT_MAX;
 679
 680                 int ret = s->d->cache_miss(b, s, bio, sectors);
 681                 if (ret != MAP_CONTINUE)
 682                         return ret;
 683
 684                 /* if this was a complete miss we shouldn't get here */
 685                 BUG_ON(bio_sectors <= sectors);
 686         }
 687
 688         if (!KEY_SIZE(k))
 689                 return MAP_CONTINUE;
 690
 691         /* XXX: figure out best pointer - for multiple cache devices */
 692         ptr = 0;
 693
 694         PTR_BUCKET(b->c, k, ptr)->prio = INITIAL_PRIO;
 695
 696         if (KEY_DIRTY(k))
 697                 s->read_dirty_data = true;
 698
 699         n = bio_next_split(bio, min_t(uint64_t, INT_MAX,
 700                                       KEY_OFFSET(k) - bio->bi_iter.bi_sector),
 701                            GFP_NOIO, s->d->bio_split);
 702
 703         bio_key = &container_of(n, struct bbio, bio)->key;
 704         bch_bkey_copy_single_ptr(bio_key, k, ptr);
 705
 706         bch_cut_front(&KEY(s->iop.inode, n->bi_iter.bi_sector, 0), bio_key);
 707         bch_cut_back(&KEY(s->iop.inode, bio_end_sector(n), 0), bio_key);
 708
 709         n->bi_end_io    = bch_cache_read_endio;
 710         n->bi_private   = &s->cl;
 711
 712         /*
 713          * The bucket we're reading from might be reused while our bio
 714          * is in flight, and we could then end up reading the wrong
 715          * data.
 716          *
 717          * We guard against this by checking (in cache_read_endio()) if
 718          * the pointer is stale again; if so, we treat it as an error
 719          * and reread from the backing device (but we don't pass that
 720          * error up anywhere).
 721          */
 722
 723         __bch_submit_bbio(n, b->c);
 724         return n == bio ? MAP_DONE : MAP_CONTINUE;
 725 }
 726
 727 static void cache_lookup(struct closure *cl)
 728 {
 729         struct search *s = container_of(cl, struct search, iop.cl);
 730         struct bio *bio = &s->bio.bio;
 731         int ret;
 732
 733         bch_btree_op_init(&s->op, -1);
 734
 735         ret = bch_btree_map_keys(&s->op, s->iop.c,
 736                                  &KEY(s->iop.inode, bio->bi_iter.bi_sector, 0),
 737                                  cache_lookup_fn, MAP_END_KEY);
 738         if (ret == -EAGAIN)
 739                 continue_at(cl, cache_lookup, bcache_wq);
 740
 741         closure_return(cl);
 742 }
 743
 744 /* Common code for the make_request functions */
 745
 746 static void request_endio(struct bio *bio, int error)
 747 {
 748         struct closure *cl = bio->bi_private;
 749
 750         if (error) {
 751                 struct search *s = container_of(cl, struct search, cl);
 752                 s->iop.error = error;
 753                 /* Only cache read errors are recoverable */
 754                 s->recoverable = false;
 755         }
 756
 757         bio_put(bio);
 758         closure_put(cl);
 759 }
 760
 761 static void bio_complete(struct search *s)
 762 {
 763         if (s->orig_bio) {
 764                 int cpu, rw = bio_data_dir(s->orig_bio);
 765                 unsigned long duration = jiffies - s->start_time;
 766
 767                 cpu = part_stat_lock();
 768                 part_round_stats(cpu, &s->d->disk->part0);
 769                 part_stat_add(cpu, &s->d->disk->part0, ticks[rw], duration);
 770                 part_stat_unlock();
 771
 772                 trace_bcache_request_end(s->d, s->orig_bio);
 773                 bio_endio(s->orig_bio, s->iop.error);
 774                 s->orig_bio = NULL;
 775         }
 776 }
 777
 778 static void do_bio_hook(struct search *s, struct bio *orig_bio)
 779 {
 780         struct bio *bio = &s->bio.bio;
 781
 782         bio_init(bio);
 783         __bio_clone_fast(bio, orig_bio);
 784         bio->bi_end_io          = request_endio;
 785         bio->bi_private         = &s->cl;
 786
 787         atomic_set(&bio->bi_cnt, 3);
 788 }
 789
 790 static void search_free(struct closure *cl)
 791 {
 792         struct search *s = container_of(cl, struct search, cl);
 793         bio_complete(s);
 794
 795         if (s->iop.bio)
 796                 bio_put(s->iop.bio);
 797
 798         closure_debug_destroy(cl);
 799         mempool_free(s, s->d->c->search);
 800 }
 801
 802 static inline struct search *search_alloc(struct bio *bio,
 803                                           struct bcache_device *d)
 804 {
 805         struct search *s;
 806
 807         s = mempool_alloc(d->c->search, GFP_NOIO);
 808
 809         closure_init(&s->cl, NULL);
 810         do_bio_hook(s, bio);
 811
 812         s->orig_bio             = bio;
 813         s->cache_miss           = NULL;
 814         s->d                    = d;
 815         s->recoverable          = 1;
 816         s->write                = (bio->bi_rw & REQ_WRITE) != 0;
 817         s->read_dirty_data      = 0;
 818         s->start_time           = jiffies;
 819
 820         s->iop.c                = d->c;
 821         s->iop.bio              = NULL;
 822         s->iop.inode            = d->id;
 823         s->iop.write_point      = hash_long((unsigned long) current, 16);
 824         s->iop.write_prio       = 0;
 825         s->iop.error            = 0;
 826         s->iop.flags            = 0;
 827         s->iop.flush_journal    = (bio->bi_rw & (REQ_FLUSH|REQ_FUA)) != 0;
 828
 829         return s;
 830 }
 831
 832 /* Cached devices */
 833
 834 static void cached_dev_bio_complete(struct closure *cl)
 835 {
 836         struct search *s = container_of(cl, struct search, cl);
 837         struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 838
 839         search_free(cl);
 840         cached_dev_put(dc);
 841 }
 842
 843 /* Process reads */
 844
 845 static void cached_dev_cache_miss_done(struct closure *cl)
 846 {
 847         struct search *s = container_of(cl, struct search, cl);
 848
 849         if (s->iop.replace_collision)
 850                 bch_mark_cache_miss_collision(s->iop.c, s->d);
 851
 852         if (s->iop.bio) {
 853                 int i;
 854                 struct bio_vec *bv;
 855
 856                 bio_for_each_segment_all(bv, s->iop.bio, i)
 857                         __free_page(bv->bv_page);
 858         }
 859
 860         cached_dev_bio_complete(cl);
 861 }
 862
 863 static void cached_dev_read_error(struct closure *cl)
 864 {
 865         struct search *s = container_of(cl, struct search, cl);
 866         struct bio *bio = &s->bio.bio;
 867
 868         if (s->recoverable) {
 869                 /* Retry from the backing device: */
 870                 trace_bcache_read_retry(s->orig_bio);
 871
 872                 s->iop.error = 0;
 873                 do_bio_hook(s, s->orig_bio);
 874
 875                 /* XXX: invalidate cache */
 876
 877                 closure_bio_submit(bio, cl, s->d);
 878         }
 879
 880         continue_at(cl, cached_dev_cache_miss_done, NULL);
 881 }
 882
 883 static void cached_dev_read_done(struct closure *cl)
 884 {
 885         struct search *s = container_of(cl, struct search, cl);
 886         struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
 887
 888         /*
 889          * We had a cache miss; cache_bio now contains data ready to be inserted
 890          * into the cache.
 891          *
 892          * First, we copy the data we just read from cache_bio's bounce buffers
 893          * to the buffers the original bio pointed to:
 894          */
 895
 896         if (s->iop.bio) {
 897                 bio_reset(s->iop.bio);
 898                 s->iop.bio->bi_iter.bi_sector = s->cache_miss->bi_iter.bi_sector;
 899                 s->iop.bio->bi_bdev = s->cache_miss->bi_bdev;
 900                 s->iop.bio->bi_iter.bi_size = s->insert_bio_sectors << 9;
 901                 bch_bio_map(s->iop.bio, NULL);
 902
 903                 bio_copy_data(s->cache_miss, s->iop.bio);
 904
 905                 bio_put(s->cache_miss);
 906                 s->cache_miss = NULL;
 907         }
 908
 909         if (verify(dc, &s->bio.bio) && s->recoverable && !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 = bio_next_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_iter.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 = bio_next_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_iter.bi_sector    = miss->bi_iter.bi_sector;
 984         cache_bio->bi_bdev              = miss->bi_bdev;
 985         cache_bio->bi_iter.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_iter.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_fast(bio, GFP_NOIO, dc->disk.bio_split);
1092
1093                 closure_bio_submit(bio, cl, s->d);
1094         }
1095
1096         closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
1097         continue_at(cl, cached_dev_write_complete, NULL);
1098 }
1099
1100 static void cached_dev_nodata(struct closure *cl)
1101 {
1102         struct search *s = container_of(cl, struct search, cl);
1103         struct bio *bio = &s->bio.bio;
1104
1105         if (s->iop.flush_journal)
1106                 bch_journal_meta(s->iop.c, cl);
1107
1108         /* If it's a flush, we send the flush to the backing device too */
1109         closure_bio_submit(bio, cl, s->d);
1110
1111         continue_at(cl, cached_dev_bio_complete, NULL);
1112 }
1113
1114 /* Cached devices - read & write stuff */
1115
1116 static void cached_dev_make_request(struct request_queue *q, struct bio *bio)
1117 {
1118         struct search *s;
1119         struct bcache_device *d = bio->bi_bdev->bd_disk->private_data;
1120         struct cached_dev *dc = container_of(d, struct cached_dev, disk);
1121         int cpu, rw = bio_data_dir(bio);
1122
1123         cpu = part_stat_lock();
1124         part_stat_inc(cpu, &d->disk->part0, ios[rw]);
1125         part_stat_add(cpu, &d->disk->part0, sectors[rw], bio_sectors(bio));
1126         part_stat_unlock();
1127
1128         bio->bi_bdev = dc->bdev;
1129         bio->bi_iter.bi_sector += dc->sb.data_offset;
1130
1131         if (cached_dev_get(dc)) {
1132                 s = search_alloc(bio, d);
1133                 trace_bcache_request_start(s->d, bio);
1134
1135                 if (!bio->bi_iter.bi_size) {
1136                         /*
1137                          * can't call bch_journal_meta from under
1138                          * generic_make_request
1139                          */
1140                         continue_at_nobarrier(&s->cl,
1141                                               cached_dev_nodata,
1142                                               bcache_wq);
1143                 } else {
1144                         s->iop.bypass = check_should_bypass(dc, bio);
1145
1146                         if (rw)
1147                                 cached_dev_write(dc, s);
1148                         else
1149                                 cached_dev_read(dc, s);
1150                 }
1151         } else {
1152                 if ((bio->bi_rw & REQ_DISCARD) &&
1153                     !blk_queue_discard(bdev_get_queue(dc->bdev)))
1154                         bio_endio(bio, 0);
1155                 else
1156                         bch_generic_make_request(bio, &d->bio_split_hook);
1157         }
1158 }
1159
1160 static int cached_dev_ioctl(struct bcache_device *d, fmode_t mode,
1161                             unsigned int cmd, unsigned long arg)
1162 {
1163         struct cached_dev *dc = container_of(d, struct cached_dev, disk);
1164         return __blkdev_driver_ioctl(dc->bdev, mode, cmd, arg);
1165 }
1166
1167 static int cached_dev_congested(void *data, int bits)
1168 {
1169         struct bcache_device *d = data;
1170         struct cached_dev *dc = container_of(d, struct cached_dev, disk);
1171         struct request_queue *q = bdev_get_queue(dc->bdev);
1172         int ret = 0;
1173
1174         if (bdi_congested(&q->backing_dev_info, bits))
1175                 return 1;
1176
1177         if (cached_dev_get(dc)) {
1178                 unsigned i;
1179                 struct cache *ca;
1180
1181                 for_each_cache(ca, d->c, i) {
1182                         q = bdev_get_queue(ca->bdev);
1183                         ret |= bdi_congested(&q->backing_dev_info, bits);
1184                 }
1185
1186                 cached_dev_put(dc);
1187         }
1188
1189         return ret;
1190 }
1191
1192 void bch_cached_dev_request_init(struct cached_dev *dc)
1193 {
1194         struct gendisk *g = dc->disk.disk;
1195
1196         g->queue->make_request_fn               = cached_dev_make_request;
1197         g->queue->backing_dev_info.congested_fn = cached_dev_congested;
1198         dc->disk.cache_miss                     = cached_dev_cache_miss;
1199         dc->disk.ioctl                          = cached_dev_ioctl;
1200 }
1201
1202 /* Flash backed devices */
1203
1204 static int flash_dev_cache_miss(struct btree *b, struct search *s,
1205                                 struct bio *bio, unsigned sectors)
1206 {
1207         struct bio_vec bv;
1208         struct bvec_iter iter;
1209
1210         /* Zero fill bio */
1211
1212         bio_for_each_segment(bv, bio, iter) {
1213                 unsigned j = min(bv.bv_len >> 9, sectors);
1214
1215                 void *p = kmap(bv.bv_page);
1216                 memset(p + bv.bv_offset, 0, j << 9);
1217                 kunmap(bv.bv_page);
1218
1219                 sectors -= j;
1220         }
1221
1222         bio_advance(bio, min(sectors << 9, bio->bi_iter.bi_size));
1223
1224         if (!bio->bi_iter.bi_size)
1225                 return MAP_DONE;
1226
1227         return MAP_CONTINUE;
1228 }
1229
1230 static void flash_dev_nodata(struct closure *cl)
1231 {
1232         struct search *s = container_of(cl, struct search, cl);
1233
1234         if (s->iop.flush_journal)
1235                 bch_journal_meta(s->iop.c, cl);
1236
1237         continue_at(cl, search_free, NULL);
1238 }
1239
1240 static void flash_dev_make_request(struct request_queue *q, struct bio *bio)
1241 {
1242         struct search *s;
1243         struct closure *cl;
1244         struct bcache_device *d = bio->bi_bdev->bd_disk->private_data;
1245         int cpu, rw = bio_data_dir(bio);
1246
1247         cpu = part_stat_lock();
1248         part_stat_inc(cpu, &d->disk->part0, ios[rw]);
1249         part_stat_add(cpu, &d->disk->part0, sectors[rw], bio_sectors(bio));
1250         part_stat_unlock();
1251
1252         s = search_alloc(bio, d);
1253         cl = &s->cl;
1254         bio = &s->bio.bio;
1255
1256         trace_bcache_request_start(s->d, bio);
1257
1258         if (!bio->bi_iter.bi_size) {
1259                 /*
1260                  * can't call bch_journal_meta from under
1261                  * generic_make_request
1262                  */
1263                 continue_at_nobarrier(&s->cl,
1264                                       flash_dev_nodata,
1265                                       bcache_wq);
1266         } else if (rw) {
1267                 bch_keybuf_check_overlapping(&s->iop.c->moving_gc_keys,
1268                                         &KEY(d->id, bio->bi_iter.bi_sector, 0),
1269                                         &KEY(d->id, bio_end_sector(bio), 0));
1270
1271                 s->iop.bypass           = (bio->bi_rw & REQ_DISCARD) != 0;
1272                 s->iop.writeback        = true;
1273                 s->iop.bio              = bio;
1274
1275                 closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
1276         } else {
1277                 closure_call(&s->iop.cl, cache_lookup, NULL, cl);
1278         }
1279
1280         continue_at(cl, search_free, NULL);
1281 }
1282
1283 static int flash_dev_ioctl(struct bcache_device *d, fmode_t mode,
1284                            unsigned int cmd, unsigned long arg)
1285 {
1286         return -ENOTTY;
1287 }
1288
1289 static int flash_dev_congested(void *data, int bits)
1290 {
1291         struct bcache_device *d = data;
1292         struct request_queue *q;
1293         struct cache *ca;
1294         unsigned i;
1295         int ret = 0;
1296
1297         for_each_cache(ca, d->c, i) {
1298                 q = bdev_get_queue(ca->bdev);
1299                 ret |= bdi_congested(&q->backing_dev_info, bits);
1300         }
1301
1302         return ret;
1303 }
1304
1305 void bch_flash_dev_request_init(struct bcache_device *d)
1306 {
1307         struct gendisk *g = d->disk;
1308
1309         g->queue->make_request_fn               = flash_dev_make_request;
1310         g->queue->backing_dev_info.congested_fn = flash_dev_congested;
1311         d->cache_miss                           = flash_dev_cache_miss;
1312         d->ioctl                                = flash_dev_ioctl;
1313 }
1314
1315 void bch_request_exit(void)
1316 {
1317 #ifdef CONFIG_CGROUP_BCACHE
1318         cgroup_unload_subsys(&bcache_subsys);
1319 #endif
1320         if (bch_search_cache)
1321                 kmem_cache_destroy(bch_search_cache);
1322 }
1323
1324 int __init bch_request_init(void)
1325 {
1326         bch_search_cache = KMEM_CACHE(search, 0);
1327         if (!bch_search_cache)
1328                 return -ENOMEM;
1329
1330 #ifdef CONFIG_CGROUP_BCACHE
1331         cgroup_load_subsys(&bcache_subsys);
1332         init_bch_cgroup(&bcache_default_cgroup);
1333
1334         cgroup_add_cftypes(&bcache_subsys, bch_files);
1335 #endif
1336         return 0;
1337 }