drivers/md/bcache/super.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * bcache setup/teardown code, and some metadata io - read a superblock and
   4  * figure out what to do with it.
   5  *
   6  * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
   7  * Copyright 2012 Google, Inc.
   8  */
   9
  10 #include "bcache.h"
  11 #include "btree.h"
  12 #include "debug.h"
  13 #include "extents.h"
  14 #include "request.h"
  15 #include "writeback.h"
  16
  17 #include <linux/blkdev.h>
  18 #include <linux/buffer_head.h>
  19 #include <linux/debugfs.h>
  20 #include <linux/genhd.h>
  21 #include <linux/idr.h>
  22 #include <linux/kthread.h>
  23 #include <linux/module.h>
  24 #include <linux/random.h>
  25 #include <linux/reboot.h>
  26 #include <linux/sysfs.h>
  27
  28 unsigned int bch_cutoff_writeback;
  29 unsigned int bch_cutoff_writeback_sync;
  30
  31 static const char bcache_magic[] = {
  32         0xc6, 0x85, 0x73, 0xf6, 0x4e, 0x1a, 0x45, 0xca,
  33         0x82, 0x65, 0xf5, 0x7f, 0x48, 0xba, 0x6d, 0x81
  34 };
  35
  36 static const char invalid_uuid[] = {
  37         0xa0, 0x3e, 0xf8, 0xed, 0x3e, 0xe1, 0xb8, 0x78,
  38         0xc8, 0x50, 0xfc, 0x5e, 0xcb, 0x16, 0xcd, 0x99
  39 };
  40
  41 static struct kobject *bcache_kobj;
  42 struct mutex bch_register_lock;
  43 bool bcache_is_reboot;
  44 LIST_HEAD(bch_cache_sets);
  45 static LIST_HEAD(uncached_devices);
  46
  47 static int bcache_major;
  48 static DEFINE_IDA(bcache_device_idx);
  49 static wait_queue_head_t unregister_wait;
  50 struct workqueue_struct *bcache_wq;
  51 struct workqueue_struct *bch_journal_wq;
  52
  53
  54 #define BTREE_MAX_PAGES         (256 * 1024 / PAGE_SIZE)
  55 /* limitation of partitions number on single bcache device */
  56 #define BCACHE_MINORS           128
  57 /* limitation of bcache devices number on single system */
  58 #define BCACHE_DEVICE_IDX_MAX   ((1U << MINORBITS)/BCACHE_MINORS)
  59
  60 /* Superblock */
  61
  62 static const char *read_super(struct cache_sb *sb, struct block_device *bdev,
  63                               struct page **res)
  64 {
  65         const char *err;
  66         struct cache_sb *s;
  67         struct buffer_head *bh = __bread(bdev, 1, SB_SIZE);
  68         unsigned int i;
  69
  70         if (!bh)
  71                 return "IO error";
  72
  73         s = (struct cache_sb *) bh->b_data;
  74
  75         sb->offset              = le64_to_cpu(s->offset);
  76         sb->version             = le64_to_cpu(s->version);
  77
  78         memcpy(sb->magic,       s->magic, 16);
  79         memcpy(sb->uuid,        s->uuid, 16);
  80         memcpy(sb->set_uuid,    s->set_uuid, 16);
  81         memcpy(sb->label,       s->label, SB_LABEL_SIZE);
  82
  83         sb->flags               = le64_to_cpu(s->flags);
  84         sb->seq                 = le64_to_cpu(s->seq);
  85         sb->last_mount          = le32_to_cpu(s->last_mount);
  86         sb->first_bucket        = le16_to_cpu(s->first_bucket);
  87         sb->keys                = le16_to_cpu(s->keys);
  88
  89         for (i = 0; i < SB_JOURNAL_BUCKETS; i++)
  90                 sb->d[i] = le64_to_cpu(s->d[i]);
  91
  92         pr_debug("read sb version %llu, flags %llu, seq %llu, journal size %u",
  93                  sb->version, sb->flags, sb->seq, sb->keys);
  94
  95         err = "Not a bcache superblock";
  96         if (sb->offset != SB_SECTOR)
  97                 goto err;
  98
  99         if (memcmp(sb->magic, bcache_magic, 16))
 100                 goto err;
 101
 102         err = "Too many journal buckets";
 103         if (sb->keys > SB_JOURNAL_BUCKETS)
 104                 goto err;
 105
 106         err = "Bad checksum";
 107         if (s->csum != csum_set(s))
 108                 goto err;
 109
 110         err = "Bad UUID";
 111         if (bch_is_zero(sb->uuid, 16))
 112                 goto err;
 113
 114         sb->block_size  = le16_to_cpu(s->block_size);
 115
 116         err = "Superblock block size smaller than device block size";
 117         if (sb->block_size << 9 < bdev_logical_block_size(bdev))
 118                 goto err;
 119
 120         switch (sb->version) {
 121         case BCACHE_SB_VERSION_BDEV:
 122                 sb->data_offset = BDEV_DATA_START_DEFAULT;
 123                 break;
 124         case BCACHE_SB_VERSION_BDEV_WITH_OFFSET:
 125                 sb->data_offset = le64_to_cpu(s->data_offset);
 126
 127                 err = "Bad data offset";
 128                 if (sb->data_offset < BDEV_DATA_START_DEFAULT)
 129                         goto err;
 130
 131                 break;
 132         case BCACHE_SB_VERSION_CDEV:
 133         case BCACHE_SB_VERSION_CDEV_WITH_UUID:
 134                 sb->nbuckets    = le64_to_cpu(s->nbuckets);
 135                 sb->bucket_size = le16_to_cpu(s->bucket_size);
 136
 137                 sb->nr_in_set   = le16_to_cpu(s->nr_in_set);
 138                 sb->nr_this_dev = le16_to_cpu(s->nr_this_dev);
 139
 140                 err = "Too many buckets";
 141                 if (sb->nbuckets > LONG_MAX)
 142                         goto err;
 143
 144                 err = "Not enough buckets";
 145                 if (sb->nbuckets < 1 << 7)
 146                         goto err;
 147
 148                 err = "Bad block/bucket size";
 149                 if (!is_power_of_2(sb->block_size) ||
 150                     sb->block_size > PAGE_SECTORS ||
 151                     !is_power_of_2(sb->bucket_size) ||
 152                     sb->bucket_size < PAGE_SECTORS)
 153                         goto err;
 154
 155                 err = "Invalid superblock: device too small";
 156                 if (get_capacity(bdev->bd_disk) <
 157                     sb->bucket_size * sb->nbuckets)
 158                         goto err;
 159
 160                 err = "Bad UUID";
 161                 if (bch_is_zero(sb->set_uuid, 16))
 162                         goto err;
 163
 164                 err = "Bad cache device number in set";
 165                 if (!sb->nr_in_set ||
 166                     sb->nr_in_set <= sb->nr_this_dev ||
 167                     sb->nr_in_set > MAX_CACHES_PER_SET)
 168                         goto err;
 169
 170                 err = "Journal buckets not sequential";
 171                 for (i = 0; i < sb->keys; i++)
 172                         if (sb->d[i] != sb->first_bucket + i)
 173                                 goto err;
 174
 175                 err = "Too many journal buckets";
 176                 if (sb->first_bucket + sb->keys > sb->nbuckets)
 177                         goto err;
 178
 179                 err = "Invalid superblock: first bucket comes before end of super";
 180                 if (sb->first_bucket * sb->bucket_size < 16)
 181                         goto err;
 182
 183                 break;
 184         default:
 185                 err = "Unsupported superblock version";
 186                 goto err;
 187         }
 188
 189         sb->last_mount = (u32)ktime_get_real_seconds();
 190         err = NULL;
 191
 192         get_page(bh->b_page);
 193         *res = bh->b_page;
 194 err:
 195         put_bh(bh);
 196         return err;
 197 }
 198
 199 static void write_bdev_super_endio(struct bio *bio)
 200 {
 201         struct cached_dev *dc = bio->bi_private;
 202
 203         if (bio->bi_status)
 204                 bch_count_backing_io_errors(dc, bio);
 205
 206         closure_put(&dc->sb_write);
 207 }
 208
 209 static void __write_super(struct cache_sb *sb, struct bio *bio)
 210 {
 211         struct cache_sb *out = page_address(bio_first_page_all(bio));
 212         unsigned int i;
 213
 214         bio->bi_iter.bi_sector  = SB_SECTOR;
 215         bio->bi_iter.bi_size    = SB_SIZE;
 216         bio_set_op_attrs(bio, REQ_OP_WRITE, REQ_SYNC|REQ_META);
 217         bch_bio_map(bio, NULL);
 218
 219         out->offset             = cpu_to_le64(sb->offset);
 220         out->version            = cpu_to_le64(sb->version);
 221
 222         memcpy(out->uuid,       sb->uuid, 16);
 223         memcpy(out->set_uuid,   sb->set_uuid, 16);
 224         memcpy(out->label,      sb->label, SB_LABEL_SIZE);
 225
 226         out->flags              = cpu_to_le64(sb->flags);
 227         out->seq                = cpu_to_le64(sb->seq);
 228
 229         out->last_mount         = cpu_to_le32(sb->last_mount);
 230         out->first_bucket       = cpu_to_le16(sb->first_bucket);
 231         out->keys               = cpu_to_le16(sb->keys);
 232
 233         for (i = 0; i < sb->keys; i++)
 234                 out->d[i] = cpu_to_le64(sb->d[i]);
 235
 236         out->csum = csum_set(out);
 237
 238         pr_debug("ver %llu, flags %llu, seq %llu",
 239                  sb->version, sb->flags, sb->seq);
 240
 241         submit_bio(bio);
 242 }
 243
 244 static void bch_write_bdev_super_unlock(struct closure *cl)
 245 {
 246         struct cached_dev *dc = container_of(cl, struct cached_dev, sb_write);
 247
 248         up(&dc->sb_write_mutex);
 249 }
 250
 251 void bch_write_bdev_super(struct cached_dev *dc, struct closure *parent)
 252 {
 253         struct closure *cl = &dc->sb_write;
 254         struct bio *bio = &dc->sb_bio;
 255
 256         down(&dc->sb_write_mutex);
 257         closure_init(cl, parent);
 258
 259         bio_reset(bio);
 260         bio_set_dev(bio, dc->bdev);
 261         bio->bi_end_io  = write_bdev_super_endio;
 262         bio->bi_private = dc;
 263
 264         closure_get(cl);
 265         /* I/O request sent to backing device */
 266         __write_super(&dc->sb, bio);
 267
 268         closure_return_with_destructor(cl, bch_write_bdev_super_unlock);
 269 }
 270
 271 static void write_super_endio(struct bio *bio)
 272 {
 273         struct cache *ca = bio->bi_private;
 274
 275         /* is_read = 0 */
 276         bch_count_io_errors(ca, bio->bi_status, 0,
 277                             "writing superblock");
 278         closure_put(&ca->set->sb_write);
 279 }
 280
 281 static void bcache_write_super_unlock(struct closure *cl)
 282 {
 283         struct cache_set *c = container_of(cl, struct cache_set, sb_write);
 284
 285         up(&c->sb_write_mutex);
 286 }
 287
 288 void bcache_write_super(struct cache_set *c)
 289 {
 290         struct closure *cl = &c->sb_write;
 291         struct cache *ca;
 292         unsigned int i;
 293
 294         down(&c->sb_write_mutex);
 295         closure_init(cl, &c->cl);
 296
 297         c->sb.seq++;
 298
 299         for_each_cache(ca, c, i) {
 300                 struct bio *bio = &ca->sb_bio;
 301
 302                 ca->sb.version          = BCACHE_SB_VERSION_CDEV_WITH_UUID;
 303                 ca->sb.seq              = c->sb.seq;
 304                 ca->sb.last_mount       = c->sb.last_mount;
 305
 306                 SET_CACHE_SYNC(&ca->sb, CACHE_SYNC(&c->sb));
 307
 308                 bio_reset(bio);
 309                 bio_set_dev(bio, ca->bdev);
 310                 bio->bi_end_io  = write_super_endio;
 311                 bio->bi_private = ca;
 312
 313                 closure_get(cl);
 314                 __write_super(&ca->sb, bio);
 315         }
 316
 317         closure_return_with_destructor(cl, bcache_write_super_unlock);
 318 }
 319
 320 /* UUID io */
 321
 322 static void uuid_endio(struct bio *bio)
 323 {
 324         struct closure *cl = bio->bi_private;
 325         struct cache_set *c = container_of(cl, struct cache_set, uuid_write);
 326
 327         cache_set_err_on(bio->bi_status, c, "accessing uuids");
 328         bch_bbio_free(bio, c);
 329         closure_put(cl);
 330 }
 331
 332 static void uuid_io_unlock(struct closure *cl)
 333 {
 334         struct cache_set *c = container_of(cl, struct cache_set, uuid_write);
 335
 336         up(&c->uuid_write_mutex);
 337 }
 338
 339 static void uuid_io(struct cache_set *c, int op, unsigned long op_flags,
 340                     struct bkey *k, struct closure *parent)
 341 {
 342         struct closure *cl = &c->uuid_write;
 343         struct uuid_entry *u;
 344         unsigned int i;
 345         char buf[80];
 346
 347         BUG_ON(!parent);
 348         down(&c->uuid_write_mutex);
 349         closure_init(cl, parent);
 350
 351         for (i = 0; i < KEY_PTRS(k); i++) {
 352                 struct bio *bio = bch_bbio_alloc(c);
 353
 354                 bio->bi_opf = REQ_SYNC | REQ_META | op_flags;
 355                 bio->bi_iter.bi_size = KEY_SIZE(k) << 9;
 356
 357                 bio->bi_end_io  = uuid_endio;
 358                 bio->bi_private = cl;
 359                 bio_set_op_attrs(bio, op, REQ_SYNC|REQ_META|op_flags);
 360                 bch_bio_map(bio, c->uuids);
 361
 362                 bch_submit_bbio(bio, c, k, i);
 363
 364                 if (op != REQ_OP_WRITE)
 365                         break;
 366         }
 367
 368         bch_extent_to_text(buf, sizeof(buf), k);
 369         pr_debug("%s UUIDs at %s", op == REQ_OP_WRITE ? "wrote" : "read", buf);
 370
 371         for (u = c->uuids; u < c->uuids + c->nr_uuids; u++)
 372                 if (!bch_is_zero(u->uuid, 16))
 373                         pr_debug("Slot %zi: %pU: %s: 1st: %u last: %u inv: %u",
 374                                  u - c->uuids, u->uuid, u->label,
 375                                  u->first_reg, u->last_reg, u->invalidated);
 376
 377         closure_return_with_destructor(cl, uuid_io_unlock);
 378 }
 379
 380 static char *uuid_read(struct cache_set *c, struct jset *j, struct closure *cl)
 381 {
 382         struct bkey *k = &j->uuid_bucket;
 383
 384         if (__bch_btree_ptr_invalid(c, k))
 385                 return "bad uuid pointer";
 386
 387         bkey_copy(&c->uuid_bucket, k);
 388         uuid_io(c, REQ_OP_READ, 0, k, cl);
 389
 390         if (j->version < BCACHE_JSET_VERSION_UUIDv1) {
 391                 struct uuid_entry_v0    *u0 = (void *) c->uuids;
 392                 struct uuid_entry       *u1 = (void *) c->uuids;
 393                 int i;
 394
 395                 closure_sync(cl);
 396
 397                 /*
 398                  * Since the new uuid entry is bigger than the old, we have to
 399                  * convert starting at the highest memory address and work down
 400                  * in order to do it in place
 401                  */
 402
 403                 for (i = c->nr_uuids - 1;
 404                      i >= 0;
 405                      --i) {
 406                         memcpy(u1[i].uuid,      u0[i].uuid, 16);
 407                         memcpy(u1[i].label,     u0[i].label, 32);
 408
 409                         u1[i].first_reg         = u0[i].first_reg;
 410                         u1[i].last_reg          = u0[i].last_reg;
 411                         u1[i].invalidated       = u0[i].invalidated;
 412
 413                         u1[i].flags     = 0;
 414                         u1[i].sectors   = 0;
 415                 }
 416         }
 417
 418         return NULL;
 419 }
 420
 421 static int __uuid_write(struct cache_set *c)
 422 {
 423         BKEY_PADDED(key) k;
 424         struct closure cl;
 425         struct cache *ca;
 426
 427         closure_init_stack(&cl);
 428         lockdep_assert_held(&bch_register_lock);
 429
 430         if (bch_bucket_alloc_set(c, RESERVE_BTREE, &k.key, 1, true))
 431                 return 1;
 432
 433         SET_KEY_SIZE(&k.key, c->sb.bucket_size);
 434         uuid_io(c, REQ_OP_WRITE, 0, &k.key, &cl);
 435         closure_sync(&cl);
 436
 437         /* Only one bucket used for uuid write */
 438         ca = PTR_CACHE(c, &k.key, 0);
 439         atomic_long_add(ca->sb.bucket_size, &ca->meta_sectors_written);
 440
 441         bkey_copy(&c->uuid_bucket, &k.key);
 442         bkey_put(c, &k.key);
 443         return 0;
 444 }
 445
 446 int bch_uuid_write(struct cache_set *c)
 447 {
 448         int ret = __uuid_write(c);
 449
 450         if (!ret)
 451                 bch_journal_meta(c, NULL);
 452
 453         return ret;
 454 }
 455
 456 static struct uuid_entry *uuid_find(struct cache_set *c, const char *uuid)
 457 {
 458         struct uuid_entry *u;
 459
 460         for (u = c->uuids;
 461              u < c->uuids + c->nr_uuids; u++)
 462                 if (!memcmp(u->uuid, uuid, 16))
 463                         return u;
 464
 465         return NULL;
 466 }
 467
 468 static struct uuid_entry *uuid_find_empty(struct cache_set *c)
 469 {
 470         static const char zero_uuid[16] = "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";
 471
 472         return uuid_find(c, zero_uuid);
 473 }
 474
 475 /*
 476  * Bucket priorities/gens:
 477  *
 478  * For each bucket, we store on disk its
 479  *   8 bit gen
 480  *  16 bit priority
 481  *
 482  * See alloc.c for an explanation of the gen. The priority is used to implement
 483  * lru (and in the future other) cache replacement policies; for most purposes
 484  * it's just an opaque integer.
 485  *
 486  * The gens and the priorities don't have a whole lot to do with each other, and
 487  * it's actually the gens that must be written out at specific times - it's no
 488  * big deal if the priorities don't get written, if we lose them we just reuse
 489  * buckets in suboptimal order.
 490  *
 491  * On disk they're stored in a packed array, and in as many buckets are required
 492  * to fit them all. The buckets we use to store them form a list; the journal
 493  * header points to the first bucket, the first bucket points to the second
 494  * bucket, et cetera.
 495  *
 496  * This code is used by the allocation code; periodically (whenever it runs out
 497  * of buckets to allocate from) the allocation code will invalidate some
 498  * buckets, but it can't use those buckets until their new gens are safely on
 499  * disk.
 500  */
 501
 502 static void prio_endio(struct bio *bio)
 503 {
 504         struct cache *ca = bio->bi_private;
 505
 506         cache_set_err_on(bio->bi_status, ca->set, "accessing priorities");
 507         bch_bbio_free(bio, ca->set);
 508         closure_put(&ca->prio);
 509 }
 510
 511 static void prio_io(struct cache *ca, uint64_t bucket, int op,
 512                     unsigned long op_flags)
 513 {
 514         struct closure *cl = &ca->prio;
 515         struct bio *bio = bch_bbio_alloc(ca->set);
 516
 517         closure_init_stack(cl);
 518
 519         bio->bi_iter.bi_sector  = bucket * ca->sb.bucket_size;
 520         bio_set_dev(bio, ca->bdev);
 521         bio->bi_iter.bi_size    = bucket_bytes(ca);
 522
 523         bio->bi_end_io  = prio_endio;
 524         bio->bi_private = ca;
 525         bio_set_op_attrs(bio, op, REQ_SYNC|REQ_META|op_flags);
 526         bch_bio_map(bio, ca->disk_buckets);
 527
 528         closure_bio_submit(ca->set, bio, &ca->prio);
 529         closure_sync(cl);
 530 }
 531
 532 void bch_prio_write(struct cache *ca)
 533 {
 534         int i;
 535         struct bucket *b;
 536         struct closure cl;
 537
 538         closure_init_stack(&cl);
 539
 540         lockdep_assert_held(&ca->set->bucket_lock);
 541
 542         ca->disk_buckets->seq++;
 543
 544         atomic_long_add(ca->sb.bucket_size * prio_buckets(ca),
 545                         &ca->meta_sectors_written);
 546
 547         //pr_debug("free %zu, free_inc %zu, unused %zu", fifo_used(&ca->free),
 548         //       fifo_used(&ca->free_inc), fifo_used(&ca->unused));
 549
 550         for (i = prio_buckets(ca) - 1; i >= 0; --i) {
 551                 long bucket;
 552                 struct prio_set *p = ca->disk_buckets;
 553                 struct bucket_disk *d = p->data;
 554                 struct bucket_disk *end = d + prios_per_bucket(ca);
 555
 556                 for (b = ca->buckets + i * prios_per_bucket(ca);
 557                      b < ca->buckets + ca->sb.nbuckets && d < end;
 558                      b++, d++) {
 559                         d->prio = cpu_to_le16(b->prio);
 560                         d->gen = b->gen;
 561                 }
 562
 563                 p->next_bucket  = ca->prio_buckets[i + 1];
 564                 p->magic        = pset_magic(&ca->sb);
 565                 p->csum         = bch_crc64(&p->magic, bucket_bytes(ca) - 8);
 566
 567                 bucket = bch_bucket_alloc(ca, RESERVE_PRIO, true);
 568                 BUG_ON(bucket == -1);
 569
 570                 mutex_unlock(&ca->set->bucket_lock);
 571                 prio_io(ca, bucket, REQ_OP_WRITE, 0);
 572                 mutex_lock(&ca->set->bucket_lock);
 573
 574                 ca->prio_buckets[i] = bucket;
 575                 atomic_dec_bug(&ca->buckets[bucket].pin);
 576         }
 577
 578         mutex_unlock(&ca->set->bucket_lock);
 579
 580         bch_journal_meta(ca->set, &cl);
 581         closure_sync(&cl);
 582
 583         mutex_lock(&ca->set->bucket_lock);
 584
 585         /*
 586          * Don't want the old priorities to get garbage collected until after we
 587          * finish writing the new ones, and they're journalled
 588          */
 589         for (i = 0; i < prio_buckets(ca); i++) {
 590                 if (ca->prio_last_buckets[i])
 591                         __bch_bucket_free(ca,
 592                                 &ca->buckets[ca->prio_last_buckets[i]]);
 593
 594                 ca->prio_last_buckets[i] = ca->prio_buckets[i];
 595         }
 596 }
 597
 598 static void prio_read(struct cache *ca, uint64_t bucket)
 599 {
 600         struct prio_set *p = ca->disk_buckets;
 601         struct bucket_disk *d = p->data + prios_per_bucket(ca), *end = d;
 602         struct bucket *b;
 603         unsigned int bucket_nr = 0;
 604
 605         for (b = ca->buckets;
 606              b < ca->buckets + ca->sb.nbuckets;
 607              b++, d++) {
 608                 if (d == end) {
 609                         ca->prio_buckets[bucket_nr] = bucket;
 610                         ca->prio_last_buckets[bucket_nr] = bucket;
 611                         bucket_nr++;
 612
 613                         prio_io(ca, bucket, REQ_OP_READ, 0);
 614
 615                         if (p->csum !=
 616                             bch_crc64(&p->magic, bucket_bytes(ca) - 8))
 617                                 pr_warn("bad csum reading priorities");
 618
 619                         if (p->magic != pset_magic(&ca->sb))
 620                                 pr_warn("bad magic reading priorities");
 621
 622                         bucket = p->next_bucket;
 623                         d = p->data;
 624                 }
 625
 626                 b->prio = le16_to_cpu(d->prio);
 627                 b->gen = b->last_gc = d->gen;
 628         }
 629 }
 630
 631 /* Bcache device */
 632
 633 static int open_dev(struct block_device *b, fmode_t mode)
 634 {
 635         struct bcache_device *d = b->bd_disk->private_data;
 636
 637         if (test_bit(BCACHE_DEV_CLOSING, &d->flags))
 638                 return -ENXIO;
 639
 640         closure_get(&d->cl);
 641         return 0;
 642 }
 643
 644 static void release_dev(struct gendisk *b, fmode_t mode)
 645 {
 646         struct bcache_device *d = b->private_data;
 647
 648         closure_put(&d->cl);
 649 }
 650
 651 static int ioctl_dev(struct block_device *b, fmode_t mode,
 652                      unsigned int cmd, unsigned long arg)
 653 {
 654         struct bcache_device *d = b->bd_disk->private_data;
 655
 656         return d->ioctl(d, mode, cmd, arg);
 657 }
 658
 659 static const struct block_device_operations bcache_ops = {
 660         .open           = open_dev,
 661         .release        = release_dev,
 662         .ioctl          = ioctl_dev,
 663         .owner          = THIS_MODULE,
 664 };
 665
 666 void bcache_device_stop(struct bcache_device *d)
 667 {
 668         if (!test_and_set_bit(BCACHE_DEV_CLOSING, &d->flags))
 669                 /*
 670                  * closure_fn set to
 671                  * - cached device: cached_dev_flush()
 672                  * - flash dev: flash_dev_flush()
 673                  */
 674                 closure_queue(&d->cl);
 675 }
 676
 677 static void bcache_device_unlink(struct bcache_device *d)
 678 {
 679         lockdep_assert_held(&bch_register_lock);
 680
 681         if (d->c && !test_and_set_bit(BCACHE_DEV_UNLINK_DONE, &d->flags)) {
 682                 unsigned int i;
 683                 struct cache *ca;
 684
 685                 sysfs_remove_link(&d->c->kobj, d->name);
 686                 sysfs_remove_link(&d->kobj, "cache");
 687
 688                 for_each_cache(ca, d->c, i)
 689                         bd_unlink_disk_holder(ca->bdev, d->disk);
 690         }
 691 }
 692
 693 static void bcache_device_link(struct bcache_device *d, struct cache_set *c,
 694                                const char *name)
 695 {
 696         unsigned int i;
 697         struct cache *ca;
 698         int ret;
 699
 700         for_each_cache(ca, d->c, i)
 701                 bd_link_disk_holder(ca->bdev, d->disk);
 702
 703         snprintf(d->name, BCACHEDEVNAME_SIZE,
 704                  "%s%u", name, d->id);
 705
 706         ret = sysfs_create_link(&d->kobj, &c->kobj, "cache");
 707         if (ret < 0)
 708                 pr_err("Couldn't create device -> cache set symlink");
 709
 710         ret = sysfs_create_link(&c->kobj, &d->kobj, d->name);
 711         if (ret < 0)
 712                 pr_err("Couldn't create cache set -> device symlink");
 713
 714         clear_bit(BCACHE_DEV_UNLINK_DONE, &d->flags);
 715 }
 716
 717 static void bcache_device_detach(struct bcache_device *d)
 718 {
 719         lockdep_assert_held(&bch_register_lock);
 720
 721         atomic_dec(&d->c->attached_dev_nr);
 722
 723         if (test_bit(BCACHE_DEV_DETACHING, &d->flags)) {
 724                 struct uuid_entry *u = d->c->uuids + d->id;
 725
 726                 SET_UUID_FLASH_ONLY(u, 0);
 727                 memcpy(u->uuid, invalid_uuid, 16);
 728                 u->invalidated = cpu_to_le32((u32)ktime_get_real_seconds());
 729                 bch_uuid_write(d->c);
 730         }
 731
 732         bcache_device_unlink(d);
 733
 734         d->c->devices[d->id] = NULL;
 735         closure_put(&d->c->caching);
 736         d->c = NULL;
 737 }
 738
 739 static void bcache_device_attach(struct bcache_device *d, struct cache_set *c,
 740                                  unsigned int id)
 741 {
 742         d->id = id;
 743         d->c = c;
 744         c->devices[id] = d;
 745
 746         if (id >= c->devices_max_used)
 747                 c->devices_max_used = id + 1;
 748
 749         closure_get(&c->caching);
 750 }
 751
 752 static inline int first_minor_to_idx(int first_minor)
 753 {
 754         return (first_minor/BCACHE_MINORS);
 755 }
 756
 757 static inline int idx_to_first_minor(int idx)
 758 {
 759         return (idx * BCACHE_MINORS);
 760 }
 761
 762 static void bcache_device_free(struct bcache_device *d)
 763 {
 764         lockdep_assert_held(&bch_register_lock);
 765
 766         pr_info("%s stopped", d->disk->disk_name);
 767
 768         if (d->c)
 769                 bcache_device_detach(d);
 770         if (d->disk && d->disk->flags & GENHD_FL_UP)
 771                 del_gendisk(d->disk);
 772         if (d->disk && d->disk->queue)
 773                 blk_cleanup_queue(d->disk->queue);
 774         if (d->disk) {
 775                 ida_simple_remove(&bcache_device_idx,
 776                                   first_minor_to_idx(d->disk->first_minor));
 777                 put_disk(d->disk);
 778         }
 779
 780         bioset_exit(&d->bio_split);
 781         kvfree(d->full_dirty_stripes);
 782         kvfree(d->stripe_sectors_dirty);
 783
 784         closure_debug_destroy(&d->cl);
 785 }
 786
 787 static int bcache_device_init(struct bcache_device *d, unsigned int block_size,
 788                               sector_t sectors)
 789 {
 790         struct request_queue *q;
 791         const size_t max_stripes = min_t(size_t, INT_MAX,
 792                                          SIZE_MAX / sizeof(atomic_t));
 793         size_t n;
 794         int idx;
 795
 796         if (!d->stripe_size)
 797                 d->stripe_size = 1 << 31;
 798
 799         d->nr_stripes = DIV_ROUND_UP_ULL(sectors, d->stripe_size);
 800
 801         if (!d->nr_stripes || d->nr_stripes > max_stripes) {
 802                 pr_err("nr_stripes too large or invalid: %u (start sector beyond end of disk?)",
 803                         (unsigned int)d->nr_stripes);
 804                 return -ENOMEM;
 805         }
 806
 807         n = d->nr_stripes * sizeof(atomic_t);
 808         d->stripe_sectors_dirty = kvzalloc(n, GFP_KERNEL);
 809         if (!d->stripe_sectors_dirty)
 810                 return -ENOMEM;
 811
 812         n = BITS_TO_LONGS(d->nr_stripes) * sizeof(unsigned long);
 813         d->full_dirty_stripes = kvzalloc(n, GFP_KERNEL);
 814         if (!d->full_dirty_stripes)
 815                 return -ENOMEM;
 816
 817         idx = ida_simple_get(&bcache_device_idx, 0,
 818                                 BCACHE_DEVICE_IDX_MAX, GFP_KERNEL);
 819         if (idx < 0)
 820                 return idx;
 821
 822         if (bioset_init(&d->bio_split, 4, offsetof(struct bbio, bio),
 823                         BIOSET_NEED_BVECS|BIOSET_NEED_RESCUER))
 824                 goto err;
 825
 826         d->disk = alloc_disk(BCACHE_MINORS);
 827         if (!d->disk)
 828                 goto err;
 829
 830         set_capacity(d->disk, sectors);
 831         snprintf(d->disk->disk_name, DISK_NAME_LEN, "bcache%i", idx);
 832
 833         d->disk->major          = bcache_major;
 834         d->disk->first_minor    = idx_to_first_minor(idx);
 835         d->disk->fops           = &bcache_ops;
 836         d->disk->private_data   = d;
 837
 838         q = blk_alloc_queue(GFP_KERNEL);
 839         if (!q)
 840                 return -ENOMEM;
 841
 842         blk_queue_make_request(q, NULL);
 843         d->disk->queue                  = q;
 844         q->queuedata                    = d;
 845         q->backing_dev_info->congested_data = d;
 846         q->limits.max_hw_sectors        = UINT_MAX;
 847         q->limits.max_sectors           = UINT_MAX;
 848         q->limits.max_segment_size      = UINT_MAX;
 849         q->limits.max_segments          = BIO_MAX_PAGES;
 850         blk_queue_max_discard_sectors(q, UINT_MAX);
 851         q->limits.discard_granularity   = 512;
 852         q->limits.io_min                = block_size;
 853         q->limits.logical_block_size    = block_size;
 854         q->limits.physical_block_size   = block_size;
 855         blk_queue_flag_set(QUEUE_FLAG_NONROT, d->disk->queue);
 856         blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, d->disk->queue);
 857         blk_queue_flag_set(QUEUE_FLAG_DISCARD, d->disk->queue);
 858
 859         blk_queue_write_cache(q, true, true);
 860
 861         return 0;
 862
 863 err:
 864         ida_simple_remove(&bcache_device_idx, idx);
 865         return -ENOMEM;
 866
 867 }
 868
 869 /* Cached device */
 870
 871 static void calc_cached_dev_sectors(struct cache_set *c)
 872 {
 873         uint64_t sectors = 0;
 874         struct cached_dev *dc;
 875
 876         list_for_each_entry(dc, &c->cached_devs, list)
 877                 sectors += bdev_sectors(dc->bdev);
 878
 879         c->cached_dev_sectors = sectors;
 880 }
 881
 882 #define BACKING_DEV_OFFLINE_TIMEOUT 5
 883 static int cached_dev_status_update(void *arg)
 884 {
 885         struct cached_dev *dc = arg;
 886         struct request_queue *q;
 887
 888         /*
 889          * If this delayed worker is stopping outside, directly quit here.
 890          * dc->io_disable might be set via sysfs interface, so check it
 891          * here too.
 892          */
 893         while (!kthread_should_stop() && !dc->io_disable) {
 894                 q = bdev_get_queue(dc->bdev);
 895                 if (blk_queue_dying(q))
 896                         dc->offline_seconds++;
 897                 else
 898                         dc->offline_seconds = 0;
 899
 900                 if (dc->offline_seconds >= BACKING_DEV_OFFLINE_TIMEOUT) {
 901                         pr_err("%s: device offline for %d seconds",
 902                                dc->backing_dev_name,
 903                                BACKING_DEV_OFFLINE_TIMEOUT);
 904                         pr_err("%s: disable I/O request due to backing "
 905                                "device offline", dc->disk.name);
 906                         dc->io_disable = true;
 907                         /* let others know earlier that io_disable is true */
 908                         smp_mb();
 909                         bcache_device_stop(&dc->disk);
 910                         break;
 911                 }
 912                 schedule_timeout_interruptible(HZ);
 913         }
 914
 915         wait_for_kthread_stop();
 916         return 0;
 917 }
 918
 919
 920 int bch_cached_dev_run(struct cached_dev *dc)
 921 {
 922         struct bcache_device *d = &dc->disk;
 923         char *buf = kmemdup_nul(dc->sb.label, SB_LABEL_SIZE, GFP_KERNEL);
 924         char *env[] = {
 925                 "DRIVER=bcache",
 926                 kasprintf(GFP_KERNEL, "CACHED_UUID=%pU", dc->sb.uuid),
 927                 kasprintf(GFP_KERNEL, "CACHED_LABEL=%s", buf ? : ""),
 928                 NULL,
 929         };
 930
 931         if (dc->io_disable) {
 932                 pr_err("I/O disabled on cached dev %s",
 933                        dc->backing_dev_name);
 934                 return -EIO;
 935         }
 936
 937         if (atomic_xchg(&dc->running, 1)) {
 938                 kfree(env[1]);
 939                 kfree(env[2]);
 940                 kfree(buf);
 941                 pr_info("cached dev %s is running already",
 942                        dc->backing_dev_name);
 943                 return -EBUSY;
 944         }
 945
 946         if (!d->c &&
 947             BDEV_STATE(&dc->sb) != BDEV_STATE_NONE) {
 948                 struct closure cl;
 949
 950                 closure_init_stack(&cl);
 951
 952                 SET_BDEV_STATE(&dc->sb, BDEV_STATE_STALE);
 953                 bch_write_bdev_super(dc, &cl);
 954                 closure_sync(&cl);
 955         }
 956
 957         add_disk(d->disk);
 958         bd_link_disk_holder(dc->bdev, dc->disk.disk);
 959         /*
 960          * won't show up in the uevent file, use udevadm monitor -e instead
 961          * only class / kset properties are persistent
 962          */
 963         kobject_uevent_env(&disk_to_dev(d->disk)->kobj, KOBJ_CHANGE, env);
 964         kfree(env[1]);
 965         kfree(env[2]);
 966         kfree(buf);
 967
 968         if (sysfs_create_link(&d->kobj, &disk_to_dev(d->disk)->kobj, "dev") ||
 969             sysfs_create_link(&disk_to_dev(d->disk)->kobj,
 970                               &d->kobj, "bcache")) {
 971                 pr_err("Couldn't create bcache dev <-> disk sysfs symlinks");
 972                 return -ENOMEM;
 973         }
 974
 975         dc->status_update_thread = kthread_run(cached_dev_status_update,
 976                                                dc, "bcache_status_update");
 977         if (IS_ERR(dc->status_update_thread)) {
 978                 pr_warn("failed to create bcache_status_update kthread, "
 979                         "continue to run without monitoring backing "
 980                         "device status");
 981         }
 982
 983         return 0;
 984 }
 985
 986 /*
 987  * If BCACHE_DEV_RATE_DW_RUNNING is set, it means routine of the delayed
 988  * work dc->writeback_rate_update is running. Wait until the routine
 989  * quits (BCACHE_DEV_RATE_DW_RUNNING is clear), then continue to
 990  * cancel it. If BCACHE_DEV_RATE_DW_RUNNING is not clear after time_out
 991  * seconds, give up waiting here and continue to cancel it too.
 992  */
 993 static void cancel_writeback_rate_update_dwork(struct cached_dev *dc)
 994 {
 995         int time_out = WRITEBACK_RATE_UPDATE_SECS_MAX * HZ;
 996
 997         do {
 998                 if (!test_bit(BCACHE_DEV_RATE_DW_RUNNING,
 999                               &dc->disk.flags))
1000                         break;
1001                 time_out--;
1002                 schedule_timeout_interruptible(1);
1003         } while (time_out > 0);
1004
1005         if (time_out == 0)
1006                 pr_warn("give up waiting for dc->writeback_write_update to quit");
1007
1008         cancel_delayed_work_sync(&dc->writeback_rate_update);
1009 }
1010
1011 static void cached_dev_detach_finish(struct work_struct *w)
1012 {
1013         struct cached_dev *dc = container_of(w, struct cached_dev, detach);
1014         struct closure cl;
1015
1016         closure_init_stack(&cl);
1017
1018         BUG_ON(!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags));
1019         BUG_ON(refcount_read(&dc->count));
1020
1021
1022         if (test_and_clear_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags))
1023                 cancel_writeback_rate_update_dwork(dc);
1024
1025         if (!IS_ERR_OR_NULL(dc->writeback_thread)) {
1026                 kthread_stop(dc->writeback_thread);
1027                 dc->writeback_thread = NULL;
1028         }
1029
1030         memset(&dc->sb.set_uuid, 0, 16);
1031         SET_BDEV_STATE(&dc->sb, BDEV_STATE_NONE);
1032
1033         bch_write_bdev_super(dc, &cl);
1034         closure_sync(&cl);
1035
1036         mutex_lock(&bch_register_lock);
1037
1038         calc_cached_dev_sectors(dc->disk.c);
1039         bcache_device_detach(&dc->disk);
1040         list_move(&dc->list, &uncached_devices);
1041
1042         clear_bit(BCACHE_DEV_DETACHING, &dc->disk.flags);
1043         clear_bit(BCACHE_DEV_UNLINK_DONE, &dc->disk.flags);
1044
1045         mutex_unlock(&bch_register_lock);
1046
1047         pr_info("Caching disabled for %s", dc->backing_dev_name);
1048
1049         /* Drop ref we took in cached_dev_detach() */
1050         closure_put(&dc->disk.cl);
1051 }
1052
1053 void bch_cached_dev_detach(struct cached_dev *dc)
1054 {
1055         lockdep_assert_held(&bch_register_lock);
1056
1057         if (test_bit(BCACHE_DEV_CLOSING, &dc->disk.flags))
1058                 return;
1059
1060         if (test_and_set_bit(BCACHE_DEV_DETACHING, &dc->disk.flags))
1061                 return;
1062
1063         /*
1064          * Block the device from being closed and freed until we're finished
1065          * detaching
1066          */
1067         closure_get(&dc->disk.cl);
1068
1069         bch_writeback_queue(dc);
1070
1071         cached_dev_put(dc);
1072 }
1073
1074 int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c,
1075                           uint8_t *set_uuid)
1076 {
1077         uint32_t rtime = cpu_to_le32((u32)ktime_get_real_seconds());
1078         struct uuid_entry *u;
1079         struct cached_dev *exist_dc, *t;
1080         int ret = 0;
1081
1082         if ((set_uuid && memcmp(set_uuid, c->sb.set_uuid, 16)) ||
1083             (!set_uuid && memcmp(dc->sb.set_uuid, c->sb.set_uuid, 16)))
1084                 return -ENOENT;
1085
1086         if (dc->disk.c) {
1087                 pr_err("Can't attach %s: already attached",
1088                        dc->backing_dev_name);
1089                 return -EINVAL;
1090         }
1091
1092         if (test_bit(CACHE_SET_STOPPING, &c->flags)) {
1093                 pr_err("Can't attach %s: shutting down",
1094                        dc->backing_dev_name);
1095                 return -EINVAL;
1096         }
1097
1098         if (dc->sb.block_size < c->sb.block_size) {
1099                 /* Will die */
1100                 pr_err("Couldn't attach %s: block size less than set's block size",
1101                        dc->backing_dev_name);
1102                 return -EINVAL;
1103         }
1104
1105         /* Check whether already attached */
1106         list_for_each_entry_safe(exist_dc, t, &c->cached_devs, list) {
1107                 if (!memcmp(dc->sb.uuid, exist_dc->sb.uuid, 16)) {
1108                         pr_err("Tried to attach %s but duplicate UUID already attached",
1109                                 dc->backing_dev_name);
1110
1111                         return -EINVAL;
1112                 }
1113         }
1114
1115         u = uuid_find(c, dc->sb.uuid);
1116
1117         if (u &&
1118             (BDEV_STATE(&dc->sb) == BDEV_STATE_STALE ||
1119              BDEV_STATE(&dc->sb) == BDEV_STATE_NONE)) {
1120                 memcpy(u->uuid, invalid_uuid, 16);
1121                 u->invalidated = cpu_to_le32((u32)ktime_get_real_seconds());
1122                 u = NULL;
1123         }
1124
1125         if (!u) {
1126                 if (BDEV_STATE(&dc->sb) == BDEV_STATE_DIRTY) {
1127                         pr_err("Couldn't find uuid for %s in set",
1128                                dc->backing_dev_name);
1129                         return -ENOENT;
1130                 }
1131
1132                 u = uuid_find_empty(c);
1133                 if (!u) {
1134                         pr_err("Not caching %s, no room for UUID",
1135                                dc->backing_dev_name);
1136                         return -EINVAL;
1137                 }
1138         }
1139
1140         /*
1141          * Deadlocks since we're called via sysfs...
1142          * sysfs_remove_file(&dc->kobj, &sysfs_attach);
1143          */
1144
1145         if (bch_is_zero(u->uuid, 16)) {
1146                 struct closure cl;
1147
1148                 closure_init_stack(&cl);
1149
1150                 memcpy(u->uuid, dc->sb.uuid, 16);
1151                 memcpy(u->label, dc->sb.label, SB_LABEL_SIZE);
1152                 u->first_reg = u->last_reg = rtime;
1153                 bch_uuid_write(c);
1154
1155                 memcpy(dc->sb.set_uuid, c->sb.set_uuid, 16);
1156                 SET_BDEV_STATE(&dc->sb, BDEV_STATE_CLEAN);
1157
1158                 bch_write_bdev_super(dc, &cl);
1159                 closure_sync(&cl);
1160         } else {
1161                 u->last_reg = rtime;
1162                 bch_uuid_write(c);
1163         }
1164
1165         bcache_device_attach(&dc->disk, c, u - c->uuids);
1166         list_move(&dc->list, &c->cached_devs);
1167         calc_cached_dev_sectors(c);
1168
1169         /*
1170          * dc->c must be set before dc->count != 0 - paired with the mb in
1171          * cached_dev_get()
1172          */
1173         smp_wmb();
1174         refcount_set(&dc->count, 1);
1175
1176         /* Block writeback thread, but spawn it */
1177         down_write(&dc->writeback_lock);
1178         if (bch_cached_dev_writeback_start(dc)) {
1179                 up_write(&dc->writeback_lock);
1180                 pr_err("Couldn't start writeback facilities for %s",
1181                        dc->disk.disk->disk_name);
1182                 return -ENOMEM;
1183         }
1184
1185         if (BDEV_STATE(&dc->sb) == BDEV_STATE_DIRTY) {
1186                 atomic_set(&dc->has_dirty, 1);
1187                 bch_writeback_queue(dc);
1188         }
1189
1190         bch_sectors_dirty_init(&dc->disk);
1191
1192         ret = bch_cached_dev_run(dc);
1193         if (ret && (ret != -EBUSY)) {
1194                 up_write(&dc->writeback_lock);
1195                 /*
1196                  * bch_register_lock is held, bcache_device_stop() is not
1197                  * able to be directly called. The kthread and kworker
1198                  * created previously in bch_cached_dev_writeback_start()
1199                  * have to be stopped manually here.
1200                  */
1201                 kthread_stop(dc->writeback_thread);
1202                 cancel_writeback_rate_update_dwork(dc);
1203                 pr_err("Couldn't run cached device %s",
1204                        dc->backing_dev_name);
1205                 return ret;
1206         }
1207
1208         bcache_device_link(&dc->disk, c, "bdev");
1209         atomic_inc(&c->attached_dev_nr);
1210
1211         /* Allow the writeback thread to proceed */
1212         up_write(&dc->writeback_lock);
1213
1214         pr_info("Caching %s as %s on set %pU",
1215                 dc->backing_dev_name,
1216                 dc->disk.disk->disk_name,
1217                 dc->disk.c->sb.set_uuid);
1218         return 0;
1219 }
1220
1221 /* when dc->disk.kobj released */
1222 void bch_cached_dev_release(struct kobject *kobj)
1223 {
1224         struct cached_dev *dc = container_of(kobj, struct cached_dev,
1225                                              disk.kobj);
1226         kfree(dc);
1227         module_put(THIS_MODULE);
1228 }
1229
1230 static void cached_dev_free(struct closure *cl)
1231 {
1232         struct cached_dev *dc = container_of(cl, struct cached_dev, disk.cl);
1233
1234         if (test_and_clear_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags))
1235                 cancel_writeback_rate_update_dwork(dc);
1236
1237         if (!IS_ERR_OR_NULL(dc->writeback_thread))
1238                 kthread_stop(dc->writeback_thread);
1239         if (!IS_ERR_OR_NULL(dc->status_update_thread))
1240                 kthread_stop(dc->status_update_thread);
1241
1242         mutex_lock(&bch_register_lock);
1243
1244         if (atomic_read(&dc->running))
1245                 bd_unlink_disk_holder(dc->bdev, dc->disk.disk);
1246         bcache_device_free(&dc->disk);
1247         list_del(&dc->list);
1248
1249         mutex_unlock(&bch_register_lock);
1250
1251         if (!IS_ERR_OR_NULL(dc->bdev))
1252                 blkdev_put(dc->bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
1253
1254         wake_up(&unregister_wait);
1255
1256         kobject_put(&dc->disk.kobj);
1257 }
1258
1259 static void cached_dev_flush(struct closure *cl)
1260 {
1261         struct cached_dev *dc = container_of(cl, struct cached_dev, disk.cl);
1262         struct bcache_device *d = &dc->disk;
1263
1264         mutex_lock(&bch_register_lock);
1265         bcache_device_unlink(d);
1266         mutex_unlock(&bch_register_lock);
1267
1268         bch_cache_accounting_destroy(&dc->accounting);
1269         kobject_del(&d->kobj);
1270
1271         continue_at(cl, cached_dev_free, system_wq);
1272 }
1273
1274 static int cached_dev_init(struct cached_dev *dc, unsigned int block_size)
1275 {
1276         int ret;
1277         struct io *io;
1278         struct request_queue *q = bdev_get_queue(dc->bdev);
1279
1280         __module_get(THIS_MODULE);
1281         INIT_LIST_HEAD(&dc->list);
1282         closure_init(&dc->disk.cl, NULL);
1283         set_closure_fn(&dc->disk.cl, cached_dev_flush, system_wq);
1284         kobject_init(&dc->disk.kobj, &bch_cached_dev_ktype);
1285         INIT_WORK(&dc->detach, cached_dev_detach_finish);
1286         sema_init(&dc->sb_write_mutex, 1);
1287         INIT_LIST_HEAD(&dc->io_lru);
1288         spin_lock_init(&dc->io_lock);
1289         bch_cache_accounting_init(&dc->accounting, &dc->disk.cl);
1290
1291         dc->sequential_cutoff           = 4 << 20;
1292
1293         for (io = dc->io; io < dc->io + RECENT_IO; io++) {
1294                 list_add(&io->lru, &dc->io_lru);
1295                 hlist_add_head(&io->hash, dc->io_hash + RECENT_IO);
1296         }
1297
1298         dc->disk.stripe_size = q->limits.io_opt >> 9;
1299
1300         if (dc->disk.stripe_size)
1301                 dc->partial_stripes_expensive =
1302                         q->limits.raid_partial_stripes_expensive;
1303
1304         ret = bcache_device_init(&dc->disk, block_size,
1305                          dc->bdev->bd_part->nr_sects - dc->sb.data_offset);
1306         if (ret)
1307                 return ret;
1308
1309         dc->disk.disk->queue->backing_dev_info->ra_pages =
1310                 max(dc->disk.disk->queue->backing_dev_info->ra_pages,
1311                     q->backing_dev_info->ra_pages);
1312
1313         atomic_set(&dc->io_errors, 0);
1314         dc->io_disable = false;
1315         dc->error_limit = DEFAULT_CACHED_DEV_ERROR_LIMIT;
1316         /* default to auto */
1317         dc->stop_when_cache_set_failed = BCH_CACHED_DEV_STOP_AUTO;
1318
1319         bch_cached_dev_request_init(dc);
1320         bch_cached_dev_writeback_init(dc);
1321         return 0;
1322 }
1323
1324 /* Cached device - bcache superblock */
1325
1326 static int register_bdev(struct cache_sb *sb, struct page *sb_page,
1327                                  struct block_device *bdev,
1328                                  struct cached_dev *dc)
1329 {
1330         const char *err = "cannot allocate memory";
1331         struct cache_set *c;
1332         int ret = -ENOMEM;
1333
1334         bdevname(bdev, dc->backing_dev_name);
1335         memcpy(&dc->sb, sb, sizeof(struct cache_sb));
1336         dc->bdev = bdev;
1337         dc->bdev->bd_holder = dc;
1338
1339         bio_init(&dc->sb_bio, dc->sb_bio.bi_inline_vecs, 1);
1340         bio_first_bvec_all(&dc->sb_bio)->bv_page = sb_page;
1341         get_page(sb_page);
1342
1343
1344         if (cached_dev_init(dc, sb->block_size << 9))
1345                 goto err;
1346
1347         err = "error creating kobject";
1348         if (kobject_add(&dc->disk.kobj, &part_to_dev(bdev->bd_part)->kobj,
1349                         "bcache"))
1350                 goto err;
1351         if (bch_cache_accounting_add_kobjs(&dc->accounting, &dc->disk.kobj))
1352                 goto err;
1353
1354         pr_info("registered backing device %s", dc->backing_dev_name);
1355
1356         list_add(&dc->list, &uncached_devices);
1357         /* attach to a matched cache set if it exists */
1358         list_for_each_entry(c, &bch_cache_sets, list)
1359                 bch_cached_dev_attach(dc, c, NULL);
1360
1361         if (BDEV_STATE(&dc->sb) == BDEV_STATE_NONE ||
1362             BDEV_STATE(&dc->sb) == BDEV_STATE_STALE) {
1363                 err = "failed to run cached device";
1364                 ret = bch_cached_dev_run(dc);
1365                 if (ret)
1366                         goto err;
1367         }
1368
1369         return 0;
1370 err:
1371         pr_notice("error %s: %s", dc->backing_dev_name, err);
1372         bcache_device_stop(&dc->disk);
1373         return ret;
1374 }
1375
1376 /* Flash only volumes */
1377
1378 /* When d->kobj released */
1379 void bch_flash_dev_release(struct kobject *kobj)
1380 {
1381         struct bcache_device *d = container_of(kobj, struct bcache_device,
1382                                                kobj);
1383         kfree(d);
1384 }
1385
1386 static void flash_dev_free(struct closure *cl)
1387 {
1388         struct bcache_device *d = container_of(cl, struct bcache_device, cl);
1389
1390         mutex_lock(&bch_register_lock);
1391         atomic_long_sub(bcache_dev_sectors_dirty(d),
1392                         &d->c->flash_dev_dirty_sectors);
1393         bcache_device_free(d);
1394         mutex_unlock(&bch_register_lock);
1395         kobject_put(&d->kobj);
1396 }
1397
1398 static void flash_dev_flush(struct closure *cl)
1399 {
1400         struct bcache_device *d = container_of(cl, struct bcache_device, cl);
1401
1402         mutex_lock(&bch_register_lock);
1403         bcache_device_unlink(d);
1404         mutex_unlock(&bch_register_lock);
1405         kobject_del(&d->kobj);
1406         continue_at(cl, flash_dev_free, system_wq);
1407 }
1408
1409 static int flash_dev_run(struct cache_set *c, struct uuid_entry *u)
1410 {
1411         struct bcache_device *d = kzalloc(sizeof(struct bcache_device),
1412                                           GFP_KERNEL);
1413         if (!d)
1414                 return -ENOMEM;
1415
1416         closure_init(&d->cl, NULL);
1417         set_closure_fn(&d->cl, flash_dev_flush, system_wq);
1418
1419         kobject_init(&d->kobj, &bch_flash_dev_ktype);
1420
1421         if (bcache_device_init(d, block_bytes(c), u->sectors))
1422                 goto err;
1423
1424         bcache_device_attach(d, c, u - c->uuids);
1425         bch_sectors_dirty_init(d);
1426         bch_flash_dev_request_init(d);
1427         add_disk(d->disk);
1428
1429         if (kobject_add(&d->kobj, &disk_to_dev(d->disk)->kobj, "bcache"))
1430                 goto err;
1431
1432         bcache_device_link(d, c, "volume");
1433
1434         return 0;
1435 err:
1436         kobject_put(&d->kobj);
1437         return -ENOMEM;
1438 }
1439
1440 static int flash_devs_run(struct cache_set *c)
1441 {
1442         int ret = 0;
1443         struct uuid_entry *u;
1444
1445         for (u = c->uuids;
1446              u < c->uuids + c->nr_uuids && !ret;
1447              u++)
1448                 if (UUID_FLASH_ONLY(u))
1449                         ret = flash_dev_run(c, u);
1450
1451         return ret;
1452 }
1453
1454 int bch_flash_dev_create(struct cache_set *c, uint64_t size)
1455 {
1456         struct uuid_entry *u;
1457
1458         if (test_bit(CACHE_SET_STOPPING, &c->flags))
1459                 return -EINTR;
1460
1461         if (!test_bit(CACHE_SET_RUNNING, &c->flags))
1462                 return -EPERM;
1463
1464         u = uuid_find_empty(c);
1465         if (!u) {
1466                 pr_err("Can't create volume, no room for UUID");
1467                 return -EINVAL;
1468         }
1469
1470         get_random_bytes(u->uuid, 16);
1471         memset(u->label, 0, 32);
1472         u->first_reg = u->last_reg = cpu_to_le32((u32)ktime_get_real_seconds());
1473
1474         SET_UUID_FLASH_ONLY(u, 1);
1475         u->sectors = size >> 9;
1476
1477         bch_uuid_write(c);
1478
1479         return flash_dev_run(c, u);
1480 }
1481
1482 bool bch_cached_dev_error(struct cached_dev *dc)
1483 {
1484         if (!dc || test_bit(BCACHE_DEV_CLOSING, &dc->disk.flags))
1485                 return false;
1486
1487         dc->io_disable = true;
1488         /* make others know io_disable is true earlier */
1489         smp_mb();
1490
1491         pr_err("stop %s: too many IO errors on backing device %s\n",
1492                 dc->disk.disk->disk_name, dc->backing_dev_name);
1493
1494         bcache_device_stop(&dc->disk);
1495         return true;
1496 }
1497
1498 /* Cache set */
1499
1500 __printf(2, 3)
1501 bool bch_cache_set_error(struct cache_set *c, const char *fmt, ...)
1502 {
1503         va_list args;
1504
1505         if (c->on_error != ON_ERROR_PANIC &&
1506             test_bit(CACHE_SET_STOPPING, &c->flags))
1507                 return false;
1508
1509         if (test_and_set_bit(CACHE_SET_IO_DISABLE, &c->flags))
1510                 pr_info("CACHE_SET_IO_DISABLE already set");
1511
1512         /*
1513          * XXX: we can be called from atomic context
1514          * acquire_console_sem();
1515          */
1516
1517         pr_err("bcache: error on %pU: ", c->sb.set_uuid);
1518
1519         va_start(args, fmt);
1520         vprintk(fmt, args);
1521         va_end(args);
1522
1523         pr_err(", disabling caching\n");
1524
1525         if (c->on_error == ON_ERROR_PANIC)
1526                 panic("panic forced after error\n");
1527
1528         bch_cache_set_unregister(c);
1529         return true;
1530 }
1531
1532 /* When c->kobj released */
1533 void bch_cache_set_release(struct kobject *kobj)
1534 {
1535         struct cache_set *c = container_of(kobj, struct cache_set, kobj);
1536
1537         kfree(c);
1538         module_put(THIS_MODULE);
1539 }
1540
1541 static void cache_set_free(struct closure *cl)
1542 {
1543         struct cache_set *c = container_of(cl, struct cache_set, cl);
1544         struct cache *ca;
1545         unsigned int i;
1546
1547         debugfs_remove(c->debug);
1548
1549         bch_open_buckets_free(c);
1550         bch_btree_cache_free(c);
1551         bch_journal_free(c);
1552
1553         mutex_lock(&bch_register_lock);
1554         for_each_cache(ca, c, i)
1555                 if (ca) {
1556                         ca->set = NULL;
1557                         c->cache[ca->sb.nr_this_dev] = NULL;
1558                         kobject_put(&ca->kobj);
1559                 }
1560
1561         bch_bset_sort_state_free(&c->sort);
1562         free_pages((unsigned long) c->uuids, ilog2(bucket_pages(c)));
1563
1564         if (c->moving_gc_wq)
1565                 destroy_workqueue(c->moving_gc_wq);
1566         bioset_exit(&c->bio_split);
1567         mempool_exit(&c->fill_iter);
1568         mempool_exit(&c->bio_meta);
1569         mempool_exit(&c->search);
1570         kfree(c->devices);
1571
1572         list_del(&c->list);
1573         mutex_unlock(&bch_register_lock);
1574
1575         pr_info("Cache set %pU unregistered", c->sb.set_uuid);
1576         wake_up(&unregister_wait);
1577
1578         closure_debug_destroy(&c->cl);
1579         kobject_put(&c->kobj);
1580 }
1581
1582 static void cache_set_flush(struct closure *cl)
1583 {
1584         struct cache_set *c = container_of(cl, struct cache_set, caching);
1585         struct cache *ca;
1586         struct btree *b;
1587         unsigned int i;
1588
1589         bch_cache_accounting_destroy(&c->accounting);
1590
1591         kobject_put(&c->internal);
1592         kobject_del(&c->kobj);
1593
1594         if (!IS_ERR_OR_NULL(c->gc_thread))
1595                 kthread_stop(c->gc_thread);
1596
1597         if (!IS_ERR_OR_NULL(c->root))
1598                 list_add(&c->root->list, &c->btree_cache);
1599
1600         /*
1601          * Avoid flushing cached nodes if cache set is retiring
1602          * due to too many I/O errors detected.
1603          */
1604         if (!test_bit(CACHE_SET_IO_DISABLE, &c->flags))
1605                 list_for_each_entry(b, &c->btree_cache, list) {
1606                         mutex_lock(&b->write_lock);
1607                         if (btree_node_dirty(b))
1608                                 __bch_btree_node_write(b, NULL);
1609                         mutex_unlock(&b->write_lock);
1610                 }
1611
1612         for_each_cache(ca, c, i)
1613                 if (ca->alloc_thread)
1614                         kthread_stop(ca->alloc_thread);
1615
1616         if (c->journal.cur) {
1617                 cancel_delayed_work_sync(&c->journal.work);
1618                 /* flush last journal entry if needed */
1619                 c->journal.work.work.func(&c->journal.work.work);
1620         }
1621
1622         closure_return(cl);
1623 }
1624
1625 /*
1626  * This function is only called when CACHE_SET_IO_DISABLE is set, which means
1627  * cache set is unregistering due to too many I/O errors. In this condition,
1628  * the bcache device might be stopped, it depends on stop_when_cache_set_failed
1629  * value and whether the broken cache has dirty data:
1630  *
1631  * dc->stop_when_cache_set_failed    dc->has_dirty   stop bcache device
1632  *  BCH_CACHED_STOP_AUTO               0               NO
1633  *  BCH_CACHED_STOP_AUTO               1               YES
1634  *  BCH_CACHED_DEV_STOP_ALWAYS         0               YES
1635  *  BCH_CACHED_DEV_STOP_ALWAYS         1               YES
1636  *
1637  * The expected behavior is, if stop_when_cache_set_failed is configured to
1638  * "auto" via sysfs interface, the bcache device will not be stopped if the
1639  * backing device is clean on the broken cache device.
1640  */
1641 static void conditional_stop_bcache_device(struct cache_set *c,
1642                                            struct bcache_device *d,
1643                                            struct cached_dev *dc)
1644 {
1645         if (dc->stop_when_cache_set_failed == BCH_CACHED_DEV_STOP_ALWAYS) {
1646                 pr_warn("stop_when_cache_set_failed of %s is \"always\", stop it for failed cache set %pU.",
1647                         d->disk->disk_name, c->sb.set_uuid);
1648                 bcache_device_stop(d);
1649         } else if (atomic_read(&dc->has_dirty)) {
1650                 /*
1651                  * dc->stop_when_cache_set_failed == BCH_CACHED_STOP_AUTO
1652                  * and dc->has_dirty == 1
1653                  */
1654                 pr_warn("stop_when_cache_set_failed of %s is \"auto\" and cache is dirty, stop it to avoid potential data corruption.",
1655                         d->disk->disk_name);
1656                 /*
1657                  * There might be a small time gap that cache set is
1658                  * released but bcache device is not. Inside this time
1659                  * gap, regular I/O requests will directly go into
1660                  * backing device as no cache set attached to. This
1661                  * behavior may also introduce potential inconsistence
1662                  * data in writeback mode while cache is dirty.
1663                  * Therefore before calling bcache_device_stop() due
1664                  * to a broken cache device, dc->io_disable should be
1665                  * explicitly set to true.
1666                  */
1667                 dc->io_disable = true;
1668                 /* make others know io_disable is true earlier */
1669                 smp_mb();
1670                 bcache_device_stop(d);
1671         } else {
1672                 /*
1673                  * dc->stop_when_cache_set_failed == BCH_CACHED_STOP_AUTO
1674                  * and dc->has_dirty == 0
1675                  */
1676                 pr_warn("stop_when_cache_set_failed of %s is \"auto\" and cache is clean, keep it alive.",
1677                         d->disk->disk_name);
1678         }
1679 }
1680
1681 static void __cache_set_unregister(struct closure *cl)
1682 {
1683         struct cache_set *c = container_of(cl, struct cache_set, caching);
1684         struct cached_dev *dc;
1685         struct bcache_device *d;
1686         size_t i;
1687
1688         mutex_lock(&bch_register_lock);
1689
1690         for (i = 0; i < c->devices_max_used; i++) {
1691                 d = c->devices[i];
1692                 if (!d)
1693                         continue;
1694
1695                 if (!UUID_FLASH_ONLY(&c->uuids[i]) &&
1696                     test_bit(CACHE_SET_UNREGISTERING, &c->flags)) {
1697                         dc = container_of(d, struct cached_dev, disk);
1698                         bch_cached_dev_detach(dc);
1699                         if (test_bit(CACHE_SET_IO_DISABLE, &c->flags))
1700                                 conditional_stop_bcache_device(c, d, dc);
1701                 } else {
1702                         bcache_device_stop(d);
1703                 }
1704         }
1705
1706         mutex_unlock(&bch_register_lock);
1707
1708         continue_at(cl, cache_set_flush, system_wq);
1709 }
1710
1711 void bch_cache_set_stop(struct cache_set *c)
1712 {
1713         if (!test_and_set_bit(CACHE_SET_STOPPING, &c->flags))
1714                 /* closure_fn set to __cache_set_unregister() */
1715                 closure_queue(&c->caching);
1716 }
1717
1718 void bch_cache_set_unregister(struct cache_set *c)
1719 {
1720         set_bit(CACHE_SET_UNREGISTERING, &c->flags);
1721         bch_cache_set_stop(c);
1722 }
1723
1724 #define alloc_bucket_pages(gfp, c)                      \
1725         ((void *) __get_free_pages(__GFP_ZERO|gfp, ilog2(bucket_pages(c))))
1726
1727 struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
1728 {
1729         int iter_size;
1730         struct cache_set *c = kzalloc(sizeof(struct cache_set), GFP_KERNEL);
1731
1732         if (!c)
1733                 return NULL;
1734
1735         __module_get(THIS_MODULE);
1736         closure_init(&c->cl, NULL);
1737         set_closure_fn(&c->cl, cache_set_free, system_wq);
1738
1739         closure_init(&c->caching, &c->cl);
1740         set_closure_fn(&c->caching, __cache_set_unregister, system_wq);
1741
1742         /* Maybe create continue_at_noreturn() and use it here? */
1743         closure_set_stopped(&c->cl);
1744         closure_put(&c->cl);
1745
1746         kobject_init(&c->kobj, &bch_cache_set_ktype);
1747         kobject_init(&c->internal, &bch_cache_set_internal_ktype);
1748
1749         bch_cache_accounting_init(&c->accounting, &c->cl);
1750
1751         memcpy(c->sb.set_uuid, sb->set_uuid, 16);
1752         c->sb.block_size        = sb->block_size;
1753         c->sb.bucket_size       = sb->bucket_size;
1754         c->sb.nr_in_set         = sb->nr_in_set;
1755         c->sb.last_mount        = sb->last_mount;
1756         c->bucket_bits          = ilog2(sb->bucket_size);
1757         c->block_bits           = ilog2(sb->block_size);
1758         c->nr_uuids             = bucket_bytes(c) / sizeof(struct uuid_entry);
1759         c->devices_max_used     = 0;
1760         atomic_set(&c->attached_dev_nr, 0);
1761         c->btree_pages          = bucket_pages(c);
1762         if (c->btree_pages > BTREE_MAX_PAGES)
1763                 c->btree_pages = max_t(int, c->btree_pages / 4,
1764                                        BTREE_MAX_PAGES);
1765
1766         sema_init(&c->sb_write_mutex, 1);
1767         mutex_init(&c->bucket_lock);
1768         init_waitqueue_head(&c->btree_cache_wait);
1769         init_waitqueue_head(&c->bucket_wait);
1770         init_waitqueue_head(&c->gc_wait);
1771         sema_init(&c->uuid_write_mutex, 1);
1772
1773         spin_lock_init(&c->btree_gc_time.lock);
1774         spin_lock_init(&c->btree_split_time.lock);
1775         spin_lock_init(&c->btree_read_time.lock);
1776
1777         bch_moving_init_cache_set(c);
1778
1779         INIT_LIST_HEAD(&c->list);
1780         INIT_LIST_HEAD(&c->cached_devs);
1781         INIT_LIST_HEAD(&c->btree_cache);
1782         INIT_LIST_HEAD(&c->btree_cache_freeable);
1783         INIT_LIST_HEAD(&c->btree_cache_freed);
1784         INIT_LIST_HEAD(&c->data_buckets);
1785
1786         iter_size = (sb->bucket_size / sb->block_size + 1) *
1787                 sizeof(struct btree_iter_set);
1788
1789         if (!(c->devices = kcalloc(c->nr_uuids, sizeof(void *), GFP_KERNEL)) ||
1790             mempool_init_slab_pool(&c->search, 32, bch_search_cache) ||
1791             mempool_init_kmalloc_pool(&c->bio_meta, 2,
1792                                 sizeof(struct bbio) + sizeof(struct bio_vec) *
1793                                 bucket_pages(c)) ||
1794             mempool_init_kmalloc_pool(&c->fill_iter, 1, iter_size) ||
1795             bioset_init(&c->bio_split, 4, offsetof(struct bbio, bio),
1796                         BIOSET_NEED_BVECS|BIOSET_NEED_RESCUER) ||
1797             !(c->uuids = alloc_bucket_pages(GFP_KERNEL, c)) ||
1798             !(c->moving_gc_wq = alloc_workqueue("bcache_gc",
1799                                                 WQ_MEM_RECLAIM, 0)) ||
1800             bch_journal_alloc(c) ||
1801             bch_btree_cache_alloc(c) ||
1802             bch_open_buckets_alloc(c) ||
1803             bch_bset_sort_state_init(&c->sort, ilog2(c->btree_pages)))
1804                 goto err;
1805
1806         c->congested_read_threshold_us  = 2000;
1807         c->congested_write_threshold_us = 20000;
1808         c->error_limit  = DEFAULT_IO_ERROR_LIMIT;
1809         WARN_ON(test_and_clear_bit(CACHE_SET_IO_DISABLE, &c->flags));
1810
1811         return c;
1812 err:
1813         bch_cache_set_unregister(c);
1814         return NULL;
1815 }
1816
1817 static int run_cache_set(struct cache_set *c)
1818 {
1819         const char *err = "cannot allocate memory";
1820         struct cached_dev *dc, *t;
1821         struct cache *ca;
1822         struct closure cl;
1823         unsigned int i;
1824         LIST_HEAD(journal);
1825         struct journal_replay *l;
1826
1827         closure_init_stack(&cl);
1828
1829         for_each_cache(ca, c, i)
1830                 c->nbuckets += ca->sb.nbuckets;
1831         set_gc_sectors(c);
1832
1833         if (CACHE_SYNC(&c->sb)) {
1834                 struct bkey *k;
1835                 struct jset *j;
1836
1837                 err = "cannot allocate memory for journal";
1838                 if (bch_journal_read(c, &journal))
1839                         goto err;
1840
1841                 pr_debug("btree_journal_read() done");
1842
1843                 err = "no journal entries found";
1844                 if (list_empty(&journal))
1845                         goto err;
1846
1847                 j = &list_entry(journal.prev, struct journal_replay, list)->j;
1848
1849                 err = "IO error reading priorities";
1850                 for_each_cache(ca, c, i)
1851                         prio_read(ca, j->prio_bucket[ca->sb.nr_this_dev]);
1852
1853                 /*
1854                  * If prio_read() fails it'll call cache_set_error and we'll
1855                  * tear everything down right away, but if we perhaps checked
1856                  * sooner we could avoid journal replay.
1857                  */
1858
1859                 k = &j->btree_root;
1860
1861                 err = "bad btree root";
1862                 if (__bch_btree_ptr_invalid(c, k))
1863                         goto err;
1864
1865                 err = "error reading btree root";
1866                 c->root = bch_btree_node_get(c, NULL, k,
1867                                              j->btree_level,
1868                                              true, NULL);
1869                 if (IS_ERR_OR_NULL(c->root))
1870                         goto err;
1871
1872                 list_del_init(&c->root->list);
1873                 rw_unlock(true, c->root);
1874
1875                 err = uuid_read(c, j, &cl);
1876                 if (err)
1877                         goto err;
1878
1879                 err = "error in recovery";
1880                 if (bch_btree_check(c))
1881                         goto err;
1882
1883                 bch_journal_mark(c, &journal);
1884                 bch_initial_gc_finish(c);
1885                 pr_debug("btree_check() done");
1886
1887                 /*
1888                  * bcache_journal_next() can't happen sooner, or
1889                  * btree_gc_finish() will give spurious errors about last_gc >
1890                  * gc_gen - this is a hack but oh well.
1891                  */
1892                 bch_journal_next(&c->journal);
1893
1894                 err = "error starting allocator thread";
1895                 for_each_cache(ca, c, i)
1896                         if (bch_cache_allocator_start(ca))
1897                                 goto err;
1898
1899                 /*
1900                  * First place it's safe to allocate: btree_check() and
1901                  * btree_gc_finish() have to run before we have buckets to
1902                  * allocate, and bch_bucket_alloc_set() might cause a journal
1903                  * entry to be written so bcache_journal_next() has to be called
1904                  * first.
1905                  *
1906                  * If the uuids were in the old format we have to rewrite them
1907                  * before the next journal entry is written:
1908                  */
1909                 if (j->version < BCACHE_JSET_VERSION_UUID)
1910                         __uuid_write(c);
1911
1912                 err = "bcache: replay journal failed";
1913                 if (bch_journal_replay(c, &journal))
1914                         goto err;
1915         } else {
1916                 pr_notice("invalidating existing data");
1917
1918                 for_each_cache(ca, c, i) {
1919                         unsigned int j;
1920
1921                         ca->sb.keys = clamp_t(int, ca->sb.nbuckets >> 7,
1922                                               2, SB_JOURNAL_BUCKETS);
1923
1924                         for (j = 0; j < ca->sb.keys; j++)
1925                                 ca->sb.d[j] = ca->sb.first_bucket + j;
1926                 }
1927
1928                 bch_initial_gc_finish(c);
1929
1930                 err = "error starting allocator thread";
1931                 for_each_cache(ca, c, i)
1932                         if (bch_cache_allocator_start(ca))
1933                                 goto err;
1934
1935                 mutex_lock(&c->bucket_lock);
1936                 for_each_cache(ca, c, i)
1937                         bch_prio_write(ca);
1938                 mutex_unlock(&c->bucket_lock);
1939
1940                 err = "cannot allocate new UUID bucket";
1941                 if (__uuid_write(c))
1942                         goto err;
1943
1944                 err = "cannot allocate new btree root";
1945                 c->root = __bch_btree_node_alloc(c, NULL, 0, true, NULL);
1946                 if (IS_ERR_OR_NULL(c->root))
1947                         goto err;
1948
1949                 mutex_lock(&c->root->write_lock);
1950                 bkey_copy_key(&c->root->key, &MAX_KEY);
1951                 bch_btree_node_write(c->root, &cl);
1952                 mutex_unlock(&c->root->write_lock);
1953
1954                 bch_btree_set_root(c->root);
1955                 rw_unlock(true, c->root);
1956
1957                 /*
1958                  * We don't want to write the first journal entry until
1959                  * everything is set up - fortunately journal entries won't be
1960                  * written until the SET_CACHE_SYNC() here:
1961                  */
1962                 SET_CACHE_SYNC(&c->sb, true);
1963
1964                 bch_journal_next(&c->journal);
1965                 bch_journal_meta(c, &cl);
1966         }
1967
1968         err = "error starting gc thread";
1969         if (bch_gc_thread_start(c))
1970                 goto err;
1971
1972         closure_sync(&cl);
1973         c->sb.last_mount = (u32)ktime_get_real_seconds();
1974         bcache_write_super(c);
1975
1976         list_for_each_entry_safe(dc, t, &uncached_devices, list)
1977                 bch_cached_dev_attach(dc, c, NULL);
1978
1979         flash_devs_run(c);
1980
1981         set_bit(CACHE_SET_RUNNING, &c->flags);
1982         return 0;
1983 err:
1984         while (!list_empty(&journal)) {
1985                 l = list_first_entry(&journal, struct journal_replay, list);
1986                 list_del(&l->list);
1987                 kfree(l);
1988         }
1989
1990         closure_sync(&cl);
1991
1992         bch_cache_set_error(c, "%s", err);
1993
1994         return -EIO;
1995 }
1996
1997 static bool can_attach_cache(struct cache *ca, struct cache_set *c)
1998 {
1999         return ca->sb.block_size        == c->sb.block_size &&
2000                 ca->sb.bucket_size      == c->sb.bucket_size &&
2001                 ca->sb.nr_in_set        == c->sb.nr_in_set;
2002 }
2003
2004 static const char *register_cache_set(struct cache *ca)
2005 {
2006         char buf[12];
2007         const char *err = "cannot allocate memory";
2008         struct cache_set *c;
2009
2010         list_for_each_entry(c, &bch_cache_sets, list)
2011                 if (!memcmp(c->sb.set_uuid, ca->sb.set_uuid, 16)) {
2012                         if (c->cache[ca->sb.nr_this_dev])
2013                                 return "duplicate cache set member";
2014
2015                         if (!can_attach_cache(ca, c))
2016                                 return "cache sb does not match set";
2017
2018                         if (!CACHE_SYNC(&ca->sb))
2019                                 SET_CACHE_SYNC(&c->sb, false);
2020
2021                         goto found;
2022                 }
2023
2024         c = bch_cache_set_alloc(&ca->sb);
2025         if (!c)
2026                 return err;
2027
2028         err = "error creating kobject";
2029         if (kobject_add(&c->kobj, bcache_kobj, "%pU", c->sb.set_uuid) ||
2030             kobject_add(&c->internal, &c->kobj, "internal"))
2031                 goto err;
2032
2033         if (bch_cache_accounting_add_kobjs(&c->accounting, &c->kobj))
2034                 goto err;
2035
2036         bch_debug_init_cache_set(c);
2037
2038         list_add(&c->list, &bch_cache_sets);
2039 found:
2040         sprintf(buf, "cache%i", ca->sb.nr_this_dev);
2041         if (sysfs_create_link(&ca->kobj, &c->kobj, "set") ||
2042             sysfs_create_link(&c->kobj, &ca->kobj, buf))
2043                 goto err;
2044
2045         if (ca->sb.seq > c->sb.seq) {
2046                 c->sb.version           = ca->sb.version;
2047                 memcpy(c->sb.set_uuid, ca->sb.set_uuid, 16);
2048                 c->sb.flags             = ca->sb.flags;
2049                 c->sb.seq               = ca->sb.seq;
2050                 pr_debug("set version = %llu", c->sb.version);
2051         }
2052
2053         kobject_get(&ca->kobj);
2054         ca->set = c;
2055         ca->set->cache[ca->sb.nr_this_dev] = ca;
2056         c->cache_by_alloc[c->caches_loaded++] = ca;
2057
2058         if (c->caches_loaded == c->sb.nr_in_set) {
2059                 err = "failed to run cache set";
2060                 if (run_cache_set(c) < 0)
2061                         goto err;
2062         }
2063
2064         return NULL;
2065 err:
2066         bch_cache_set_unregister(c);
2067         return err;
2068 }
2069
2070 /* Cache device */
2071
2072 /* When ca->kobj released */
2073 void bch_cache_release(struct kobject *kobj)
2074 {
2075         struct cache *ca = container_of(kobj, struct cache, kobj);
2076         unsigned int i;
2077
2078         if (ca->set) {
2079                 BUG_ON(ca->set->cache[ca->sb.nr_this_dev] != ca);
2080                 ca->set->cache[ca->sb.nr_this_dev] = NULL;
2081         }
2082
2083         free_pages((unsigned long) ca->disk_buckets, ilog2(bucket_pages(ca)));
2084         kfree(ca->prio_buckets);
2085         vfree(ca->buckets);
2086
2087         free_heap(&ca->heap);
2088         free_fifo(&ca->free_inc);
2089
2090         for (i = 0; i < RESERVE_NR; i++)
2091                 free_fifo(&ca->free[i]);
2092
2093         if (ca->sb_bio.bi_inline_vecs[0].bv_page)
2094                 put_page(bio_first_page_all(&ca->sb_bio));
2095
2096         if (!IS_ERR_OR_NULL(ca->bdev))
2097                 blkdev_put(ca->bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
2098
2099         kfree(ca);
2100         module_put(THIS_MODULE);
2101 }
2102
2103 static int cache_alloc(struct cache *ca)
2104 {
2105         size_t free;
2106         size_t btree_buckets;
2107         struct bucket *b;
2108         int ret = -ENOMEM;
2109         const char *err = NULL;
2110
2111         __module_get(THIS_MODULE);
2112         kobject_init(&ca->kobj, &bch_cache_ktype);
2113
2114         bio_init(&ca->journal.bio, ca->journal.bio.bi_inline_vecs, 8);
2115
2116         /*
2117          * when ca->sb.njournal_buckets is not zero, journal exists,
2118          * and in bch_journal_replay(), tree node may split,
2119          * so bucket of RESERVE_BTREE type is needed,
2120          * the worst situation is all journal buckets are valid journal,
2121          * and all the keys need to replay,
2122          * so the number of  RESERVE_BTREE type buckets should be as much
2123          * as journal buckets
2124          */
2125         btree_buckets = ca->sb.njournal_buckets ?: 8;
2126         free = roundup_pow_of_two(ca->sb.nbuckets) >> 10;
2127         if (!free) {
2128                 ret = -EPERM;
2129                 err = "ca->sb.nbuckets is too small";
2130                 goto err_free;
2131         }
2132
2133         if (!init_fifo(&ca->free[RESERVE_BTREE], btree_buckets,
2134                                                 GFP_KERNEL)) {
2135                 err = "ca->free[RESERVE_BTREE] alloc failed";
2136                 goto err_btree_alloc;
2137         }
2138
2139         if (!init_fifo_exact(&ca->free[RESERVE_PRIO], prio_buckets(ca),
2140                                                         GFP_KERNEL)) {
2141                 err = "ca->free[RESERVE_PRIO] alloc failed";
2142                 goto err_prio_alloc;
2143         }
2144
2145         if (!init_fifo(&ca->free[RESERVE_MOVINGGC], free, GFP_KERNEL)) {
2146                 err = "ca->free[RESERVE_MOVINGGC] alloc failed";
2147                 goto err_movinggc_alloc;
2148         }
2149
2150         if (!init_fifo(&ca->free[RESERVE_NONE], free, GFP_KERNEL)) {
2151                 err = "ca->free[RESERVE_NONE] alloc failed";
2152                 goto err_none_alloc;
2153         }
2154
2155         if (!init_fifo(&ca->free_inc, free << 2, GFP_KERNEL)) {
2156                 err = "ca->free_inc alloc failed";
2157                 goto err_free_inc_alloc;
2158         }
2159
2160         if (!init_heap(&ca->heap, free << 3, GFP_KERNEL)) {
2161                 err = "ca->heap alloc failed";
2162                 goto err_heap_alloc;
2163         }
2164
2165         ca->buckets = vzalloc(array_size(sizeof(struct bucket),
2166                               ca->sb.nbuckets));
2167         if (!ca->buckets) {
2168                 err = "ca->buckets alloc failed";
2169                 goto err_buckets_alloc;
2170         }
2171
2172         ca->prio_buckets = kzalloc(array3_size(sizeof(uint64_t),
2173                                    prio_buckets(ca), 2),
2174                                    GFP_KERNEL);
2175         if (!ca->prio_buckets) {
2176                 err = "ca->prio_buckets alloc failed";
2177                 goto err_prio_buckets_alloc;
2178         }
2179
2180         ca->disk_buckets = alloc_bucket_pages(GFP_KERNEL, ca);
2181         if (!ca->disk_buckets) {
2182                 err = "ca->disk_buckets alloc failed";
2183                 goto err_disk_buckets_alloc;
2184         }
2185
2186         ca->prio_last_buckets = ca->prio_buckets + prio_buckets(ca);
2187
2188         for_each_bucket(b, ca)
2189                 atomic_set(&b->pin, 0);
2190         return 0;
2191
2192 err_disk_buckets_alloc:
2193         kfree(ca->prio_buckets);
2194 err_prio_buckets_alloc:
2195         vfree(ca->buckets);
2196 err_buckets_alloc:
2197         free_heap(&ca->heap);
2198 err_heap_alloc:
2199         free_fifo(&ca->free_inc);
2200 err_free_inc_alloc:
2201         free_fifo(&ca->free[RESERVE_NONE]);
2202 err_none_alloc:
2203         free_fifo(&ca->free[RESERVE_MOVINGGC]);
2204 err_movinggc_alloc:
2205         free_fifo(&ca->free[RESERVE_PRIO]);
2206 err_prio_alloc:
2207         free_fifo(&ca->free[RESERVE_BTREE]);
2208 err_btree_alloc:
2209 err_free:
2210         module_put(THIS_MODULE);
2211         if (err)
2212                 pr_notice("error %s: %s", ca->cache_dev_name, err);
2213         return ret;
2214 }
2215
2216 static int register_cache(struct cache_sb *sb, struct page *sb_page,
2217                                 struct block_device *bdev, struct cache *ca)
2218 {
2219         const char *err = NULL; /* must be set for any error case */
2220         int ret = 0;
2221
2222         bdevname(bdev, ca->cache_dev_name);
2223         memcpy(&ca->sb, sb, sizeof(struct cache_sb));
2224         ca->bdev = bdev;
2225         ca->bdev->bd_holder = ca;
2226
2227         bio_init(&ca->sb_bio, ca->sb_bio.bi_inline_vecs, 1);
2228         bio_first_bvec_all(&ca->sb_bio)->bv_page = sb_page;
2229         get_page(sb_page);
2230
2231         if (blk_queue_discard(bdev_get_queue(bdev)))
2232                 ca->discard = CACHE_DISCARD(&ca->sb);
2233
2234         ret = cache_alloc(ca);
2235         if (ret != 0) {
2236                 /*
2237                  * If we failed here, it means ca->kobj is not initialized yet,
2238                  * kobject_put() won't be called and there is no chance to
2239                  * call blkdev_put() to bdev in bch_cache_release(). So we
2240                  * explicitly call blkdev_put() here.
2241                  */
2242                 blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
2243                 if (ret == -ENOMEM)
2244                         err = "cache_alloc(): -ENOMEM";
2245                 else if (ret == -EPERM)
2246                         err = "cache_alloc(): cache device is too small";
2247                 else
2248                         err = "cache_alloc(): unknown error";
2249                 goto err;
2250         }
2251
2252         if (kobject_add(&ca->kobj,
2253                         &part_to_dev(bdev->bd_part)->kobj,
2254                         "bcache")) {
2255                 err = "error calling kobject_add";
2256                 ret = -ENOMEM;
2257                 goto out;
2258         }
2259
2260         mutex_lock(&bch_register_lock);
2261         err = register_cache_set(ca);
2262         mutex_unlock(&bch_register_lock);
2263
2264         if (err) {
2265                 ret = -ENODEV;
2266                 goto out;
2267         }
2268
2269         pr_info("registered cache device %s", ca->cache_dev_name);
2270
2271 out:
2272         kobject_put(&ca->kobj);
2273
2274 err:
2275         if (err)
2276                 pr_notice("error %s: %s", ca->cache_dev_name, err);
2277
2278         return ret;
2279 }
2280
2281 /* Global interfaces/init */
2282
2283 static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
2284                                const char *buffer, size_t size);
2285 static ssize_t bch_pending_bdevs_cleanup(struct kobject *k,
2286                                          struct kobj_attribute *attr,
2287                                          const char *buffer, size_t size);
2288
2289 kobj_attribute_write(register,          register_bcache);
2290 kobj_attribute_write(register_quiet,    register_bcache);
2291 kobj_attribute_write(pendings_cleanup,  bch_pending_bdevs_cleanup);
2292
2293 static bool bch_is_open_backing(struct block_device *bdev)
2294 {
2295         struct cache_set *c, *tc;
2296         struct cached_dev *dc, *t;
2297
2298         list_for_each_entry_safe(c, tc, &bch_cache_sets, list)
2299                 list_for_each_entry_safe(dc, t, &c->cached_devs, list)
2300                         if (dc->bdev == bdev)
2301                                 return true;
2302         list_for_each_entry_safe(dc, t, &uncached_devices, list)
2303                 if (dc->bdev == bdev)
2304                         return true;
2305         return false;
2306 }
2307
2308 static bool bch_is_open_cache(struct block_device *bdev)
2309 {
2310         struct cache_set *c, *tc;
2311         struct cache *ca;
2312         unsigned int i;
2313
2314         list_for_each_entry_safe(c, tc, &bch_cache_sets, list)
2315                 for_each_cache(ca, c, i)
2316                         if (ca->bdev == bdev)
2317                                 return true;
2318         return false;
2319 }
2320
2321 static bool bch_is_open(struct block_device *bdev)
2322 {
2323         return bch_is_open_cache(bdev) || bch_is_open_backing(bdev);
2324 }
2325
2326 static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
2327                                const char *buffer, size_t size)
2328 {
2329         ssize_t ret = -EINVAL;
2330         const char *err = "cannot allocate memory";
2331         char *path = NULL;
2332         struct cache_sb *sb = NULL;
2333         struct block_device *bdev = NULL;
2334         struct page *sb_page = NULL;
2335
2336         if (!try_module_get(THIS_MODULE))
2337                 return -EBUSY;
2338
2339         /* For latest state of bcache_is_reboot */
2340         smp_mb();
2341         if (bcache_is_reboot)
2342                 return -EBUSY;
2343
2344         path = kstrndup(buffer, size, GFP_KERNEL);
2345         if (!path)
2346                 goto err;
2347
2348         sb = kmalloc(sizeof(struct cache_sb), GFP_KERNEL);
2349         if (!sb)
2350                 goto err;
2351
2352         err = "failed to open device";
2353         bdev = blkdev_get_by_path(strim(path),
2354                                   FMODE_READ|FMODE_WRITE|FMODE_EXCL,
2355                                   sb);
2356         if (IS_ERR(bdev)) {
2357                 if (bdev == ERR_PTR(-EBUSY)) {
2358                         bdev = lookup_bdev(strim(path));
2359                         mutex_lock(&bch_register_lock);
2360                         if (!IS_ERR(bdev) && bch_is_open(bdev))
2361                                 err = "device already registered";
2362                         else
2363                                 err = "device busy";
2364                         mutex_unlock(&bch_register_lock);
2365                         if (!IS_ERR(bdev))
2366                                 bdput(bdev);
2367                         if (attr == &ksysfs_register_quiet)
2368                                 goto quiet_out;
2369                 }
2370                 goto err;
2371         }
2372
2373         err = "failed to set blocksize";
2374         if (set_blocksize(bdev, 4096))
2375                 goto err_close;
2376
2377         err = read_super(sb, bdev, &sb_page);
2378         if (err)
2379                 goto err_close;
2380
2381         err = "failed to register device";
2382         if (SB_IS_BDEV(sb)) {
2383                 struct cached_dev *dc = kzalloc(sizeof(*dc), GFP_KERNEL);
2384
2385                 if (!dc)
2386                         goto err_close;
2387
2388                 mutex_lock(&bch_register_lock);
2389                 ret = register_bdev(sb, sb_page, bdev, dc);
2390                 mutex_unlock(&bch_register_lock);
2391                 /* blkdev_put() will be called in cached_dev_free() */
2392                 if (ret < 0)
2393                         goto err;
2394         } else {
2395                 struct cache *ca = kzalloc(sizeof(*ca), GFP_KERNEL);
2396
2397                 if (!ca)
2398                         goto err_close;
2399
2400                 /* blkdev_put() will be called in bch_cache_release() */
2401                 if (register_cache(sb, sb_page, bdev, ca) != 0)
2402                         goto err;
2403         }
2404 quiet_out:
2405         ret = size;
2406 out:
2407         if (sb_page)
2408                 put_page(sb_page);
2409         kfree(sb);
2410         kfree(path);
2411         module_put(THIS_MODULE);
2412         return ret;
2413
2414 err_close:
2415         blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
2416 err:
2417         pr_info("error %s: %s", path, err);
2418         goto out;
2419 }
2420
2421
2422 struct pdev {
2423         struct list_head list;
2424         struct cached_dev *dc;
2425 };
2426
2427 static ssize_t bch_pending_bdevs_cleanup(struct kobject *k,
2428                                          struct kobj_attribute *attr,
2429                                          const char *buffer,
2430                                          size_t size)
2431 {
2432         LIST_HEAD(pending_devs);
2433         ssize_t ret = size;
2434         struct cached_dev *dc, *tdc;
2435         struct pdev *pdev, *tpdev;
2436         struct cache_set *c, *tc;
2437
2438         mutex_lock(&bch_register_lock);
2439         list_for_each_entry_safe(dc, tdc, &uncached_devices, list) {
2440                 pdev = kmalloc(sizeof(struct pdev), GFP_KERNEL);
2441                 if (!pdev)
2442                         break;
2443                 pdev->dc = dc;
2444                 list_add(&pdev->list, &pending_devs);
2445         }
2446
2447         list_for_each_entry_safe(pdev, tpdev, &pending_devs, list) {
2448                 list_for_each_entry_safe(c, tc, &bch_cache_sets, list) {
2449                         char *pdev_set_uuid = pdev->dc->sb.set_uuid;
2450                         char *set_uuid = c->sb.uuid;
2451
2452                         if (!memcmp(pdev_set_uuid, set_uuid, 16)) {
2453                                 list_del(&pdev->list);
2454                                 kfree(pdev);
2455                                 break;
2456                         }
2457                 }
2458         }
2459         mutex_unlock(&bch_register_lock);
2460
2461         list_for_each_entry_safe(pdev, tpdev, &pending_devs, list) {
2462                 pr_info("delete pdev %p", pdev);
2463                 list_del(&pdev->list);
2464                 bcache_device_stop(&pdev->dc->disk);
2465                 kfree(pdev);
2466         }
2467
2468         return ret;
2469 }
2470
2471 static int bcache_reboot(struct notifier_block *n, unsigned long code, void *x)
2472 {
2473         if (bcache_is_reboot)
2474                 return NOTIFY_DONE;
2475
2476         if (code == SYS_DOWN ||
2477             code == SYS_HALT ||
2478             code == SYS_POWER_OFF) {
2479                 DEFINE_WAIT(wait);
2480                 unsigned long start = jiffies;
2481                 bool stopped = false;
2482
2483                 struct cache_set *c, *tc;
2484                 struct cached_dev *dc, *tdc;
2485
2486                 mutex_lock(&bch_register_lock);
2487
2488                 if (bcache_is_reboot)
2489                         goto out;
2490
2491                 /* New registration is rejected since now */
2492                 bcache_is_reboot = true;
2493                 /*
2494                  * Make registering caller (if there is) on other CPU
2495                  * core know bcache_is_reboot set to true earlier
2496                  */
2497                 smp_mb();
2498
2499                 if (list_empty(&bch_cache_sets) &&
2500                     list_empty(&uncached_devices))
2501                         goto out;
2502
2503                 mutex_unlock(&bch_register_lock);
2504
2505                 pr_info("Stopping all devices:");
2506
2507                 /*
2508                  * The reason bch_register_lock is not held to call
2509                  * bch_cache_set_stop() and bcache_device_stop() is to
2510                  * avoid potential deadlock during reboot, because cache
2511                  * set or bcache device stopping process will acqurie
2512                  * bch_register_lock too.
2513                  *
2514                  * We are safe here because bcache_is_reboot sets to
2515                  * true already, register_bcache() will reject new
2516                  * registration now. bcache_is_reboot also makes sure
2517                  * bcache_reboot() won't be re-entered on by other thread,
2518                  * so there is no race in following list iteration by
2519                  * list_for_each_entry_safe().
2520                  */
2521                 list_for_each_entry_safe(c, tc, &bch_cache_sets, list)
2522                         bch_cache_set_stop(c);
2523
2524                 list_for_each_entry_safe(dc, tdc, &uncached_devices, list)
2525                         bcache_device_stop(&dc->disk);
2526
2527
2528                 /*
2529                  * Give an early chance for other kthreads and
2530                  * kworkers to stop themselves
2531                  */
2532                 schedule();
2533
2534                 /* What's a condition variable? */
2535                 while (1) {
2536                         long timeout = start + 10 * HZ - jiffies;
2537
2538                         mutex_lock(&bch_register_lock);
2539                         stopped = list_empty(&bch_cache_sets) &&
2540                                 list_empty(&uncached_devices);
2541
2542                         if (timeout < 0 || stopped)
2543                                 break;
2544
2545                         prepare_to_wait(&unregister_wait, &wait,
2546                                         TASK_UNINTERRUPTIBLE);
2547
2548                         mutex_unlock(&bch_register_lock);
2549                         schedule_timeout(timeout);
2550                 }
2551
2552                 finish_wait(&unregister_wait, &wait);
2553
2554                 if (stopped)
2555                         pr_info("All devices stopped");
2556                 else
2557                         pr_notice("Timeout waiting for devices to be closed");
2558 out:
2559                 mutex_unlock(&bch_register_lock);
2560         }
2561
2562         return NOTIFY_DONE;
2563 }
2564
2565 static struct notifier_block reboot = {
2566         .notifier_call  = bcache_reboot,
2567         .priority       = INT_MAX, /* before any real devices */
2568 };
2569
2570 static void bcache_exit(void)
2571 {
2572         bch_debug_exit();
2573         bch_request_exit();
2574         if (bcache_kobj)
2575                 kobject_put(bcache_kobj);
2576         if (bcache_wq)
2577                 destroy_workqueue(bcache_wq);
2578         if (bch_journal_wq)
2579                 destroy_workqueue(bch_journal_wq);
2580
2581         if (bcache_major)
2582                 unregister_blkdev(bcache_major, "bcache");
2583         unregister_reboot_notifier(&reboot);
2584         mutex_destroy(&bch_register_lock);
2585 }
2586
2587 /* Check and fixup module parameters */
2588 static void check_module_parameters(void)
2589 {
2590         if (bch_cutoff_writeback_sync == 0)
2591                 bch_cutoff_writeback_sync = CUTOFF_WRITEBACK_SYNC;
2592         else if (bch_cutoff_writeback_sync > CUTOFF_WRITEBACK_SYNC_MAX) {
2593                 pr_warn("set bch_cutoff_writeback_sync (%u) to max value %u",
2594                         bch_cutoff_writeback_sync, CUTOFF_WRITEBACK_SYNC_MAX);
2595                 bch_cutoff_writeback_sync = CUTOFF_WRITEBACK_SYNC_MAX;
2596         }
2597
2598         if (bch_cutoff_writeback == 0)
2599                 bch_cutoff_writeback = CUTOFF_WRITEBACK;
2600         else if (bch_cutoff_writeback > CUTOFF_WRITEBACK_MAX) {
2601                 pr_warn("set bch_cutoff_writeback (%u) to max value %u",
2602                         bch_cutoff_writeback, CUTOFF_WRITEBACK_MAX);
2603                 bch_cutoff_writeback = CUTOFF_WRITEBACK_MAX;
2604         }
2605
2606         if (bch_cutoff_writeback > bch_cutoff_writeback_sync) {
2607                 pr_warn("set bch_cutoff_writeback (%u) to %u",
2608                         bch_cutoff_writeback, bch_cutoff_writeback_sync);
2609                 bch_cutoff_writeback = bch_cutoff_writeback_sync;
2610         }
2611 }
2612
2613 static int __init bcache_init(void)
2614 {
2615         static const struct attribute *files[] = {
2616                 &ksysfs_register.attr,
2617                 &ksysfs_register_quiet.attr,
2618                 &ksysfs_pendings_cleanup.attr,
2619                 NULL
2620         };
2621
2622         check_module_parameters();
2623
2624         mutex_init(&bch_register_lock);
2625         init_waitqueue_head(&unregister_wait);
2626         register_reboot_notifier(&reboot);
2627
2628         bcache_major = register_blkdev(0, "bcache");
2629         if (bcache_major < 0) {
2630                 unregister_reboot_notifier(&reboot);
2631                 mutex_destroy(&bch_register_lock);
2632                 return bcache_major;
2633         }
2634
2635         bcache_wq = alloc_workqueue("bcache", WQ_MEM_RECLAIM, 0);
2636         if (!bcache_wq)
2637                 goto err;
2638
2639         bch_journal_wq = alloc_workqueue("bch_journal", WQ_MEM_RECLAIM, 0);
2640         if (!bch_journal_wq)
2641                 goto err;
2642
2643         bcache_kobj = kobject_create_and_add("bcache", fs_kobj);
2644         if (!bcache_kobj)
2645                 goto err;
2646
2647         if (bch_request_init() ||
2648             sysfs_create_files(bcache_kobj, files))
2649                 goto err;
2650
2651         bch_debug_init();
2652         closure_debug_init();
2653
2654         bcache_is_reboot = false;
2655
2656         return 0;
2657 err:
2658         bcache_exit();
2659         return -ENOMEM;
2660 }
2661
2662 /*
2663  * Module hooks
2664  */
2665 module_exit(bcache_exit);
2666 module_init(bcache_init);
2667
2668 module_param(bch_cutoff_writeback, uint, 0);
2669 MODULE_PARM_DESC(bch_cutoff_writeback, "threshold to cutoff writeback");
2670
2671 module_param(bch_cutoff_writeback_sync, uint, 0);
2672 MODULE_PARM_DESC(bch_cutoff_writeback_sync, "hard threshold to cutoff writeback");
2673
2674 MODULE_DESCRIPTION("Bcache: a Linux block layer cache");
2675 MODULE_AUTHOR("Kent Overstreet <kent.overstreet@gmail.com>");
2676 MODULE_LICENSE("GPL");