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 kfree(env[1]); 935 kfree(env[2]); 936 kfree(buf); 937 return -EIO; 938 } 939 940 if (atomic_xchg(&dc->running, 1)) { 941 kfree(env[1]); 942 kfree(env[2]); 943 kfree(buf); 944 pr_info("cached dev %s is running already", 945 dc->backing_dev_name); 946 return -EBUSY; 947 } 948 949 if (!d->c && 950 BDEV_STATE(&dc->sb) != BDEV_STATE_NONE) { 951 struct closure cl; 952 953 closure_init_stack(&cl); 954 955 SET_BDEV_STATE(&dc->sb, BDEV_STATE_STALE); 956 bch_write_bdev_super(dc, &cl); 957 closure_sync(&cl); 958 } 959 960 add_disk(d->disk); 961 bd_link_disk_holder(dc->bdev, dc->disk.disk); 962 /* 963 * won't show up in the uevent file, use udevadm monitor -e instead 964 * only class / kset properties are persistent 965 */ 966 kobject_uevent_env(&disk_to_dev(d->disk)->kobj, KOBJ_CHANGE, env); 967 kfree(env[1]); 968 kfree(env[2]); 969 kfree(buf); 970 971 if (sysfs_create_link(&d->kobj, &disk_to_dev(d->disk)->kobj, "dev") || 972 sysfs_create_link(&disk_to_dev(d->disk)->kobj, 973 &d->kobj, "bcache")) { 974 pr_err("Couldn't create bcache dev <-> disk sysfs symlinks"); 975 return -ENOMEM; 976 } 977 978 dc->status_update_thread = kthread_run(cached_dev_status_update, 979 dc, "bcache_status_update"); 980 if (IS_ERR(dc->status_update_thread)) { 981 pr_warn("failed to create bcache_status_update kthread, " 982 "continue to run without monitoring backing " 983 "device status"); 984 } 985 986 return 0; 987 } 988 989 /* 990 * If BCACHE_DEV_RATE_DW_RUNNING is set, it means routine of the delayed 991 * work dc->writeback_rate_update is running. Wait until the routine 992 * quits (BCACHE_DEV_RATE_DW_RUNNING is clear), then continue to 993 * cancel it. If BCACHE_DEV_RATE_DW_RUNNING is not clear after time_out 994 * seconds, give up waiting here and continue to cancel it too. 995 */ 996 static void cancel_writeback_rate_update_dwork(struct cached_dev *dc) 997 { 998 int time_out = WRITEBACK_RATE_UPDATE_SECS_MAX * HZ; 999 1000 do { 1001 if (!test_bit(BCACHE_DEV_RATE_DW_RUNNING, 1002 &dc->disk.flags)) 1003 break; 1004 time_out--; 1005 schedule_timeout_interruptible(1); 1006 } while (time_out > 0); 1007 1008 if (time_out == 0) 1009 pr_warn("give up waiting for dc->writeback_write_update to quit"); 1010 1011 cancel_delayed_work_sync(&dc->writeback_rate_update); 1012 } 1013 1014 static void cached_dev_detach_finish(struct work_struct *w) 1015 { 1016 struct cached_dev *dc = container_of(w, struct cached_dev, detach); 1017 struct closure cl; 1018 1019 closure_init_stack(&cl); 1020 1021 BUG_ON(!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags)); 1022 BUG_ON(refcount_read(&dc->count)); 1023 1024 1025 if (test_and_clear_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags)) 1026 cancel_writeback_rate_update_dwork(dc); 1027 1028 if (!IS_ERR_OR_NULL(dc->writeback_thread)) { 1029 kthread_stop(dc->writeback_thread); 1030 dc->writeback_thread = NULL; 1031 } 1032 1033 memset(&dc->sb.set_uuid, 0, 16); 1034 SET_BDEV_STATE(&dc->sb, BDEV_STATE_NONE); 1035 1036 bch_write_bdev_super(dc, &cl); 1037 closure_sync(&cl); 1038 1039 mutex_lock(&bch_register_lock); 1040 1041 calc_cached_dev_sectors(dc->disk.c); 1042 bcache_device_detach(&dc->disk); 1043 list_move(&dc->list, &uncached_devices); 1044 1045 clear_bit(BCACHE_DEV_DETACHING, &dc->disk.flags); 1046 clear_bit(BCACHE_DEV_UNLINK_DONE, &dc->disk.flags); 1047 1048 mutex_unlock(&bch_register_lock); 1049 1050 pr_info("Caching disabled for %s", dc->backing_dev_name); 1051 1052 /* Drop ref we took in cached_dev_detach() */ 1053 closure_put(&dc->disk.cl); 1054 } 1055 1056 void bch_cached_dev_detach(struct cached_dev *dc) 1057 { 1058 lockdep_assert_held(&bch_register_lock); 1059 1060 if (test_bit(BCACHE_DEV_CLOSING, &dc->disk.flags)) 1061 return; 1062 1063 if (test_and_set_bit(BCACHE_DEV_DETACHING, &dc->disk.flags)) 1064 return; 1065 1066 /* 1067 * Block the device from being closed and freed until we're finished 1068 * detaching 1069 */ 1070 closure_get(&dc->disk.cl); 1071 1072 bch_writeback_queue(dc); 1073 1074 cached_dev_put(dc); 1075 } 1076 1077 int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c, 1078 uint8_t *set_uuid) 1079 { 1080 uint32_t rtime = cpu_to_le32((u32)ktime_get_real_seconds()); 1081 struct uuid_entry *u; 1082 struct cached_dev *exist_dc, *t; 1083 int ret = 0; 1084 1085 if ((set_uuid && memcmp(set_uuid, c->sb.set_uuid, 16)) || 1086 (!set_uuid && memcmp(dc->sb.set_uuid, c->sb.set_uuid, 16))) 1087 return -ENOENT; 1088 1089 if (dc->disk.c) { 1090 pr_err("Can't attach %s: already attached", 1091 dc->backing_dev_name); 1092 return -EINVAL; 1093 } 1094 1095 if (test_bit(CACHE_SET_STOPPING, &c->flags)) { 1096 pr_err("Can't attach %s: shutting down", 1097 dc->backing_dev_name); 1098 return -EINVAL; 1099 } 1100 1101 if (dc->sb.block_size < c->sb.block_size) { 1102 /* Will die */ 1103 pr_err("Couldn't attach %s: block size less than set's block size", 1104 dc->backing_dev_name); 1105 return -EINVAL; 1106 } 1107 1108 /* Check whether already attached */ 1109 list_for_each_entry_safe(exist_dc, t, &c->cached_devs, list) { 1110 if (!memcmp(dc->sb.uuid, exist_dc->sb.uuid, 16)) { 1111 pr_err("Tried to attach %s but duplicate UUID already attached", 1112 dc->backing_dev_name); 1113 1114 return -EINVAL; 1115 } 1116 } 1117 1118 u = uuid_find(c, dc->sb.uuid); 1119 1120 if (u && 1121 (BDEV_STATE(&dc->sb) == BDEV_STATE_STALE || 1122 BDEV_STATE(&dc->sb) == BDEV_STATE_NONE)) { 1123 memcpy(u->uuid, invalid_uuid, 16); 1124 u->invalidated = cpu_to_le32((u32)ktime_get_real_seconds()); 1125 u = NULL; 1126 } 1127 1128 if (!u) { 1129 if (BDEV_STATE(&dc->sb) == BDEV_STATE_DIRTY) { 1130 pr_err("Couldn't find uuid for %s in set", 1131 dc->backing_dev_name); 1132 return -ENOENT; 1133 } 1134 1135 u = uuid_find_empty(c); 1136 if (!u) { 1137 pr_err("Not caching %s, no room for UUID", 1138 dc->backing_dev_name); 1139 return -EINVAL; 1140 } 1141 } 1142 1143 /* 1144 * Deadlocks since we're called via sysfs... 1145 * sysfs_remove_file(&dc->kobj, &sysfs_attach); 1146 */ 1147 1148 if (bch_is_zero(u->uuid, 16)) { 1149 struct closure cl; 1150 1151 closure_init_stack(&cl); 1152 1153 memcpy(u->uuid, dc->sb.uuid, 16); 1154 memcpy(u->label, dc->sb.label, SB_LABEL_SIZE); 1155 u->first_reg = u->last_reg = rtime; 1156 bch_uuid_write(c); 1157 1158 memcpy(dc->sb.set_uuid, c->sb.set_uuid, 16); 1159 SET_BDEV_STATE(&dc->sb, BDEV_STATE_CLEAN); 1160 1161 bch_write_bdev_super(dc, &cl); 1162 closure_sync(&cl); 1163 } else { 1164 u->last_reg = rtime; 1165 bch_uuid_write(c); 1166 } 1167 1168 bcache_device_attach(&dc->disk, c, u - c->uuids); 1169 list_move(&dc->list, &c->cached_devs); 1170 calc_cached_dev_sectors(c); 1171 1172 /* 1173 * dc->c must be set before dc->count != 0 - paired with the mb in 1174 * cached_dev_get() 1175 */ 1176 smp_wmb(); 1177 refcount_set(&dc->count, 1); 1178 1179 /* Block writeback thread, but spawn it */ 1180 down_write(&dc->writeback_lock); 1181 if (bch_cached_dev_writeback_start(dc)) { 1182 up_write(&dc->writeback_lock); 1183 pr_err("Couldn't start writeback facilities for %s", 1184 dc->disk.disk->disk_name); 1185 return -ENOMEM; 1186 } 1187 1188 if (BDEV_STATE(&dc->sb) == BDEV_STATE_DIRTY) { 1189 atomic_set(&dc->has_dirty, 1); 1190 bch_writeback_queue(dc); 1191 } 1192 1193 bch_sectors_dirty_init(&dc->disk); 1194 1195 ret = bch_cached_dev_run(dc); 1196 if (ret && (ret != -EBUSY)) { 1197 up_write(&dc->writeback_lock); 1198 /* 1199 * bch_register_lock is held, bcache_device_stop() is not 1200 * able to be directly called. The kthread and kworker 1201 * created previously in bch_cached_dev_writeback_start() 1202 * have to be stopped manually here. 1203 */ 1204 kthread_stop(dc->writeback_thread); 1205 cancel_writeback_rate_update_dwork(dc); 1206 pr_err("Couldn't run cached device %s", 1207 dc->backing_dev_name); 1208 return ret; 1209 } 1210 1211 bcache_device_link(&dc->disk, c, "bdev"); 1212 atomic_inc(&c->attached_dev_nr); 1213 1214 /* Allow the writeback thread to proceed */ 1215 up_write(&dc->writeback_lock); 1216 1217 pr_info("Caching %s as %s on set %pU", 1218 dc->backing_dev_name, 1219 dc->disk.disk->disk_name, 1220 dc->disk.c->sb.set_uuid); 1221 return 0; 1222 } 1223 1224 /* when dc->disk.kobj released */ 1225 void bch_cached_dev_release(struct kobject *kobj) 1226 { 1227 struct cached_dev *dc = container_of(kobj, struct cached_dev, 1228 disk.kobj); 1229 kfree(dc); 1230 module_put(THIS_MODULE); 1231 } 1232 1233 static void cached_dev_free(struct closure *cl) 1234 { 1235 struct cached_dev *dc = container_of(cl, struct cached_dev, disk.cl); 1236 1237 if (test_and_clear_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags)) 1238 cancel_writeback_rate_update_dwork(dc); 1239 1240 if (!IS_ERR_OR_NULL(dc->writeback_thread)) 1241 kthread_stop(dc->writeback_thread); 1242 if (!IS_ERR_OR_NULL(dc->status_update_thread)) 1243 kthread_stop(dc->status_update_thread); 1244 1245 mutex_lock(&bch_register_lock); 1246 1247 if (atomic_read(&dc->running)) 1248 bd_unlink_disk_holder(dc->bdev, dc->disk.disk); 1249 bcache_device_free(&dc->disk); 1250 list_del(&dc->list); 1251 1252 mutex_unlock(&bch_register_lock); 1253 1254 if (!IS_ERR_OR_NULL(dc->bdev)) 1255 blkdev_put(dc->bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL); 1256 1257 wake_up(&unregister_wait); 1258 1259 kobject_put(&dc->disk.kobj); 1260 } 1261 1262 static void cached_dev_flush(struct closure *cl) 1263 { 1264 struct cached_dev *dc = container_of(cl, struct cached_dev, disk.cl); 1265 struct bcache_device *d = &dc->disk; 1266 1267 mutex_lock(&bch_register_lock); 1268 bcache_device_unlink(d); 1269 mutex_unlock(&bch_register_lock); 1270 1271 bch_cache_accounting_destroy(&dc->accounting); 1272 kobject_del(&d->kobj); 1273 1274 continue_at(cl, cached_dev_free, system_wq); 1275 } 1276 1277 static int cached_dev_init(struct cached_dev *dc, unsigned int block_size) 1278 { 1279 int ret; 1280 struct io *io; 1281 struct request_queue *q = bdev_get_queue(dc->bdev); 1282 1283 __module_get(THIS_MODULE); 1284 INIT_LIST_HEAD(&dc->list); 1285 closure_init(&dc->disk.cl, NULL); 1286 set_closure_fn(&dc->disk.cl, cached_dev_flush, system_wq); 1287 kobject_init(&dc->disk.kobj, &bch_cached_dev_ktype); 1288 INIT_WORK(&dc->detach, cached_dev_detach_finish); 1289 sema_init(&dc->sb_write_mutex, 1); 1290 INIT_LIST_HEAD(&dc->io_lru); 1291 spin_lock_init(&dc->io_lock); 1292 bch_cache_accounting_init(&dc->accounting, &dc->disk.cl); 1293 1294 dc->sequential_cutoff = 4 << 20; 1295 1296 for (io = dc->io; io < dc->io + RECENT_IO; io++) { 1297 list_add(&io->lru, &dc->io_lru); 1298 hlist_add_head(&io->hash, dc->io_hash + RECENT_IO); 1299 } 1300 1301 dc->disk.stripe_size = q->limits.io_opt >> 9; 1302 1303 if (dc->disk.stripe_size) 1304 dc->partial_stripes_expensive = 1305 q->limits.raid_partial_stripes_expensive; 1306 1307 ret = bcache_device_init(&dc->disk, block_size, 1308 dc->bdev->bd_part->nr_sects - dc->sb.data_offset); 1309 if (ret) 1310 return ret; 1311 1312 dc->disk.disk->queue->backing_dev_info->ra_pages = 1313 max(dc->disk.disk->queue->backing_dev_info->ra_pages, 1314 q->backing_dev_info->ra_pages); 1315 1316 atomic_set(&dc->io_errors, 0); 1317 dc->io_disable = false; 1318 dc->error_limit = DEFAULT_CACHED_DEV_ERROR_LIMIT; 1319 /* default to auto */ 1320 dc->stop_when_cache_set_failed = BCH_CACHED_DEV_STOP_AUTO; 1321 1322 bch_cached_dev_request_init(dc); 1323 bch_cached_dev_writeback_init(dc); 1324 return 0; 1325 } 1326 1327 /* Cached device - bcache superblock */ 1328 1329 static int register_bdev(struct cache_sb *sb, struct page *sb_page, 1330 struct block_device *bdev, 1331 struct cached_dev *dc) 1332 { 1333 const char *err = "cannot allocate memory"; 1334 struct cache_set *c; 1335 int ret = -ENOMEM; 1336 1337 bdevname(bdev, dc->backing_dev_name); 1338 memcpy(&dc->sb, sb, sizeof(struct cache_sb)); 1339 dc->bdev = bdev; 1340 dc->bdev->bd_holder = dc; 1341 1342 bio_init(&dc->sb_bio, dc->sb_bio.bi_inline_vecs, 1); 1343 bio_first_bvec_all(&dc->sb_bio)->bv_page = sb_page; 1344 get_page(sb_page); 1345 1346 1347 if (cached_dev_init(dc, sb->block_size << 9)) 1348 goto err; 1349 1350 err = "error creating kobject"; 1351 if (kobject_add(&dc->disk.kobj, &part_to_dev(bdev->bd_part)->kobj, 1352 "bcache")) 1353 goto err; 1354 if (bch_cache_accounting_add_kobjs(&dc->accounting, &dc->disk.kobj)) 1355 goto err; 1356 1357 pr_info("registered backing device %s", dc->backing_dev_name); 1358 1359 list_add(&dc->list, &uncached_devices); 1360 /* attach to a matched cache set if it exists */ 1361 list_for_each_entry(c, &bch_cache_sets, list) 1362 bch_cached_dev_attach(dc, c, NULL); 1363 1364 if (BDEV_STATE(&dc->sb) == BDEV_STATE_NONE || 1365 BDEV_STATE(&dc->sb) == BDEV_STATE_STALE) { 1366 err = "failed to run cached device"; 1367 ret = bch_cached_dev_run(dc); 1368 if (ret) 1369 goto err; 1370 } 1371 1372 return 0; 1373 err: 1374 pr_notice("error %s: %s", dc->backing_dev_name, err); 1375 bcache_device_stop(&dc->disk); 1376 return ret; 1377 } 1378 1379 /* Flash only volumes */ 1380 1381 /* When d->kobj released */ 1382 void bch_flash_dev_release(struct kobject *kobj) 1383 { 1384 struct bcache_device *d = container_of(kobj, struct bcache_device, 1385 kobj); 1386 kfree(d); 1387 } 1388 1389 static void flash_dev_free(struct closure *cl) 1390 { 1391 struct bcache_device *d = container_of(cl, struct bcache_device, cl); 1392 1393 mutex_lock(&bch_register_lock); 1394 atomic_long_sub(bcache_dev_sectors_dirty(d), 1395 &d->c->flash_dev_dirty_sectors); 1396 bcache_device_free(d); 1397 mutex_unlock(&bch_register_lock); 1398 kobject_put(&d->kobj); 1399 } 1400 1401 static void flash_dev_flush(struct closure *cl) 1402 { 1403 struct bcache_device *d = container_of(cl, struct bcache_device, cl); 1404 1405 mutex_lock(&bch_register_lock); 1406 bcache_device_unlink(d); 1407 mutex_unlock(&bch_register_lock); 1408 kobject_del(&d->kobj); 1409 continue_at(cl, flash_dev_free, system_wq); 1410 } 1411 1412 static int flash_dev_run(struct cache_set *c, struct uuid_entry *u) 1413 { 1414 struct bcache_device *d = kzalloc(sizeof(struct bcache_device), 1415 GFP_KERNEL); 1416 if (!d) 1417 return -ENOMEM; 1418 1419 closure_init(&d->cl, NULL); 1420 set_closure_fn(&d->cl, flash_dev_flush, system_wq); 1421 1422 kobject_init(&d->kobj, &bch_flash_dev_ktype); 1423 1424 if (bcache_device_init(d, block_bytes(c), u->sectors)) 1425 goto err; 1426 1427 bcache_device_attach(d, c, u - c->uuids); 1428 bch_sectors_dirty_init(d); 1429 bch_flash_dev_request_init(d); 1430 add_disk(d->disk); 1431 1432 if (kobject_add(&d->kobj, &disk_to_dev(d->disk)->kobj, "bcache")) 1433 goto err; 1434 1435 bcache_device_link(d, c, "volume"); 1436 1437 return 0; 1438 err: 1439 kobject_put(&d->kobj); 1440 return -ENOMEM; 1441 } 1442 1443 static int flash_devs_run(struct cache_set *c) 1444 { 1445 int ret = 0; 1446 struct uuid_entry *u; 1447 1448 for (u = c->uuids; 1449 u < c->uuids + c->nr_uuids && !ret; 1450 u++) 1451 if (UUID_FLASH_ONLY(u)) 1452 ret = flash_dev_run(c, u); 1453 1454 return ret; 1455 } 1456 1457 int bch_flash_dev_create(struct cache_set *c, uint64_t size) 1458 { 1459 struct uuid_entry *u; 1460 1461 if (test_bit(CACHE_SET_STOPPING, &c->flags)) 1462 return -EINTR; 1463 1464 if (!test_bit(CACHE_SET_RUNNING, &c->flags)) 1465 return -EPERM; 1466 1467 u = uuid_find_empty(c); 1468 if (!u) { 1469 pr_err("Can't create volume, no room for UUID"); 1470 return -EINVAL; 1471 } 1472 1473 get_random_bytes(u->uuid, 16); 1474 memset(u->label, 0, 32); 1475 u->first_reg = u->last_reg = cpu_to_le32((u32)ktime_get_real_seconds()); 1476 1477 SET_UUID_FLASH_ONLY(u, 1); 1478 u->sectors = size >> 9; 1479 1480 bch_uuid_write(c); 1481 1482 return flash_dev_run(c, u); 1483 } 1484 1485 bool bch_cached_dev_error(struct cached_dev *dc) 1486 { 1487 if (!dc || test_bit(BCACHE_DEV_CLOSING, &dc->disk.flags)) 1488 return false; 1489 1490 dc->io_disable = true; 1491 /* make others know io_disable is true earlier */ 1492 smp_mb(); 1493 1494 pr_err("stop %s: too many IO errors on backing device %s\n", 1495 dc->disk.disk->disk_name, dc->backing_dev_name); 1496 1497 bcache_device_stop(&dc->disk); 1498 return true; 1499 } 1500 1501 /* Cache set */ 1502 1503 __printf(2, 3) 1504 bool bch_cache_set_error(struct cache_set *c, const char *fmt, ...) 1505 { 1506 va_list args; 1507 1508 if (c->on_error != ON_ERROR_PANIC && 1509 test_bit(CACHE_SET_STOPPING, &c->flags)) 1510 return false; 1511 1512 if (test_and_set_bit(CACHE_SET_IO_DISABLE, &c->flags)) 1513 pr_info("CACHE_SET_IO_DISABLE already set"); 1514 1515 /* 1516 * XXX: we can be called from atomic context 1517 * acquire_console_sem(); 1518 */ 1519 1520 pr_err("bcache: error on %pU: ", c->sb.set_uuid); 1521 1522 va_start(args, fmt); 1523 vprintk(fmt, args); 1524 va_end(args); 1525 1526 pr_err(", disabling caching\n"); 1527 1528 if (c->on_error == ON_ERROR_PANIC) 1529 panic("panic forced after error\n"); 1530 1531 bch_cache_set_unregister(c); 1532 return true; 1533 } 1534 1535 /* When c->kobj released */ 1536 void bch_cache_set_release(struct kobject *kobj) 1537 { 1538 struct cache_set *c = container_of(kobj, struct cache_set, kobj); 1539 1540 kfree(c); 1541 module_put(THIS_MODULE); 1542 } 1543 1544 static void cache_set_free(struct closure *cl) 1545 { 1546 struct cache_set *c = container_of(cl, struct cache_set, cl); 1547 struct cache *ca; 1548 unsigned int i; 1549 1550 debugfs_remove(c->debug); 1551 1552 bch_open_buckets_free(c); 1553 bch_btree_cache_free(c); 1554 bch_journal_free(c); 1555 1556 mutex_lock(&bch_register_lock); 1557 for_each_cache(ca, c, i) 1558 if (ca) { 1559 ca->set = NULL; 1560 c->cache[ca->sb.nr_this_dev] = NULL; 1561 kobject_put(&ca->kobj); 1562 } 1563 1564 bch_bset_sort_state_free(&c->sort); 1565 free_pages((unsigned long) c->uuids, ilog2(bucket_pages(c))); 1566 1567 if (c->moving_gc_wq) 1568 destroy_workqueue(c->moving_gc_wq); 1569 bioset_exit(&c->bio_split); 1570 mempool_exit(&c->fill_iter); 1571 mempool_exit(&c->bio_meta); 1572 mempool_exit(&c->search); 1573 kfree(c->devices); 1574 1575 list_del(&c->list); 1576 mutex_unlock(&bch_register_lock); 1577 1578 pr_info("Cache set %pU unregistered", c->sb.set_uuid); 1579 wake_up(&unregister_wait); 1580 1581 closure_debug_destroy(&c->cl); 1582 kobject_put(&c->kobj); 1583 } 1584 1585 static void cache_set_flush(struct closure *cl) 1586 { 1587 struct cache_set *c = container_of(cl, struct cache_set, caching); 1588 struct cache *ca; 1589 struct btree *b; 1590 unsigned int i; 1591 1592 bch_cache_accounting_destroy(&c->accounting); 1593 1594 kobject_put(&c->internal); 1595 kobject_del(&c->kobj); 1596 1597 if (!IS_ERR_OR_NULL(c->gc_thread)) 1598 kthread_stop(c->gc_thread); 1599 1600 if (!IS_ERR_OR_NULL(c->root)) 1601 list_add(&c->root->list, &c->btree_cache); 1602 1603 /* 1604 * Avoid flushing cached nodes if cache set is retiring 1605 * due to too many I/O errors detected. 1606 */ 1607 if (!test_bit(CACHE_SET_IO_DISABLE, &c->flags)) 1608 list_for_each_entry(b, &c->btree_cache, list) { 1609 mutex_lock(&b->write_lock); 1610 if (btree_node_dirty(b)) 1611 __bch_btree_node_write(b, NULL); 1612 mutex_unlock(&b->write_lock); 1613 } 1614 1615 for_each_cache(ca, c, i) 1616 if (ca->alloc_thread) 1617 kthread_stop(ca->alloc_thread); 1618 1619 if (c->journal.cur) { 1620 cancel_delayed_work_sync(&c->journal.work); 1621 /* flush last journal entry if needed */ 1622 c->journal.work.work.func(&c->journal.work.work); 1623 } 1624 1625 closure_return(cl); 1626 } 1627 1628 /* 1629 * This function is only called when CACHE_SET_IO_DISABLE is set, which means 1630 * cache set is unregistering due to too many I/O errors. In this condition, 1631 * the bcache device might be stopped, it depends on stop_when_cache_set_failed 1632 * value and whether the broken cache has dirty data: 1633 * 1634 * dc->stop_when_cache_set_failed dc->has_dirty stop bcache device 1635 * BCH_CACHED_STOP_AUTO 0 NO 1636 * BCH_CACHED_STOP_AUTO 1 YES 1637 * BCH_CACHED_DEV_STOP_ALWAYS 0 YES 1638 * BCH_CACHED_DEV_STOP_ALWAYS 1 YES 1639 * 1640 * The expected behavior is, if stop_when_cache_set_failed is configured to 1641 * "auto" via sysfs interface, the bcache device will not be stopped if the 1642 * backing device is clean on the broken cache device. 1643 */ 1644 static void conditional_stop_bcache_device(struct cache_set *c, 1645 struct bcache_device *d, 1646 struct cached_dev *dc) 1647 { 1648 if (dc->stop_when_cache_set_failed == BCH_CACHED_DEV_STOP_ALWAYS) { 1649 pr_warn("stop_when_cache_set_failed of %s is \"always\", stop it for failed cache set %pU.", 1650 d->disk->disk_name, c->sb.set_uuid); 1651 bcache_device_stop(d); 1652 } else if (atomic_read(&dc->has_dirty)) { 1653 /* 1654 * dc->stop_when_cache_set_failed == BCH_CACHED_STOP_AUTO 1655 * and dc->has_dirty == 1 1656 */ 1657 pr_warn("stop_when_cache_set_failed of %s is \"auto\" and cache is dirty, stop it to avoid potential data corruption.", 1658 d->disk->disk_name); 1659 /* 1660 * There might be a small time gap that cache set is 1661 * released but bcache device is not. Inside this time 1662 * gap, regular I/O requests will directly go into 1663 * backing device as no cache set attached to. This 1664 * behavior may also introduce potential inconsistence 1665 * data in writeback mode while cache is dirty. 1666 * Therefore before calling bcache_device_stop() due 1667 * to a broken cache device, dc->io_disable should be 1668 * explicitly set to true. 1669 */ 1670 dc->io_disable = true; 1671 /* make others know io_disable is true earlier */ 1672 smp_mb(); 1673 bcache_device_stop(d); 1674 } else { 1675 /* 1676 * dc->stop_when_cache_set_failed == BCH_CACHED_STOP_AUTO 1677 * and dc->has_dirty == 0 1678 */ 1679 pr_warn("stop_when_cache_set_failed of %s is \"auto\" and cache is clean, keep it alive.", 1680 d->disk->disk_name); 1681 } 1682 } 1683 1684 static void __cache_set_unregister(struct closure *cl) 1685 { 1686 struct cache_set *c = container_of(cl, struct cache_set, caching); 1687 struct cached_dev *dc; 1688 struct bcache_device *d; 1689 size_t i; 1690 1691 mutex_lock(&bch_register_lock); 1692 1693 for (i = 0; i < c->devices_max_used; i++) { 1694 d = c->devices[i]; 1695 if (!d) 1696 continue; 1697 1698 if (!UUID_FLASH_ONLY(&c->uuids[i]) && 1699 test_bit(CACHE_SET_UNREGISTERING, &c->flags)) { 1700 dc = container_of(d, struct cached_dev, disk); 1701 bch_cached_dev_detach(dc); 1702 if (test_bit(CACHE_SET_IO_DISABLE, &c->flags)) 1703 conditional_stop_bcache_device(c, d, dc); 1704 } else { 1705 bcache_device_stop(d); 1706 } 1707 } 1708 1709 mutex_unlock(&bch_register_lock); 1710 1711 continue_at(cl, cache_set_flush, system_wq); 1712 } 1713 1714 void bch_cache_set_stop(struct cache_set *c) 1715 { 1716 if (!test_and_set_bit(CACHE_SET_STOPPING, &c->flags)) 1717 /* closure_fn set to __cache_set_unregister() */ 1718 closure_queue(&c->caching); 1719 } 1720 1721 void bch_cache_set_unregister(struct cache_set *c) 1722 { 1723 set_bit(CACHE_SET_UNREGISTERING, &c->flags); 1724 bch_cache_set_stop(c); 1725 } 1726 1727 #define alloc_bucket_pages(gfp, c) \ 1728 ((void *) __get_free_pages(__GFP_ZERO|gfp, ilog2(bucket_pages(c)))) 1729 1730 struct cache_set *bch_cache_set_alloc(struct cache_sb *sb) 1731 { 1732 int iter_size; 1733 struct cache_set *c = kzalloc(sizeof(struct cache_set), GFP_KERNEL); 1734 1735 if (!c) 1736 return NULL; 1737 1738 __module_get(THIS_MODULE); 1739 closure_init(&c->cl, NULL); 1740 set_closure_fn(&c->cl, cache_set_free, system_wq); 1741 1742 closure_init(&c->caching, &c->cl); 1743 set_closure_fn(&c->caching, __cache_set_unregister, system_wq); 1744 1745 /* Maybe create continue_at_noreturn() and use it here? */ 1746 closure_set_stopped(&c->cl); 1747 closure_put(&c->cl); 1748 1749 kobject_init(&c->kobj, &bch_cache_set_ktype); 1750 kobject_init(&c->internal, &bch_cache_set_internal_ktype); 1751 1752 bch_cache_accounting_init(&c->accounting, &c->cl); 1753 1754 memcpy(c->sb.set_uuid, sb->set_uuid, 16); 1755 c->sb.block_size = sb->block_size; 1756 c->sb.bucket_size = sb->bucket_size; 1757 c->sb.nr_in_set = sb->nr_in_set; 1758 c->sb.last_mount = sb->last_mount; 1759 c->bucket_bits = ilog2(sb->bucket_size); 1760 c->block_bits = ilog2(sb->block_size); 1761 c->nr_uuids = bucket_bytes(c) / sizeof(struct uuid_entry); 1762 c->devices_max_used = 0; 1763 atomic_set(&c->attached_dev_nr, 0); 1764 c->btree_pages = bucket_pages(c); 1765 if (c->btree_pages > BTREE_MAX_PAGES) 1766 c->btree_pages = max_t(int, c->btree_pages / 4, 1767 BTREE_MAX_PAGES); 1768 1769 sema_init(&c->sb_write_mutex, 1); 1770 mutex_init(&c->bucket_lock); 1771 init_waitqueue_head(&c->btree_cache_wait); 1772 init_waitqueue_head(&c->bucket_wait); 1773 init_waitqueue_head(&c->gc_wait); 1774 sema_init(&c->uuid_write_mutex, 1); 1775 1776 spin_lock_init(&c->btree_gc_time.lock); 1777 spin_lock_init(&c->btree_split_time.lock); 1778 spin_lock_init(&c->btree_read_time.lock); 1779 1780 bch_moving_init_cache_set(c); 1781 1782 INIT_LIST_HEAD(&c->list); 1783 INIT_LIST_HEAD(&c->cached_devs); 1784 INIT_LIST_HEAD(&c->btree_cache); 1785 INIT_LIST_HEAD(&c->btree_cache_freeable); 1786 INIT_LIST_HEAD(&c->btree_cache_freed); 1787 INIT_LIST_HEAD(&c->data_buckets); 1788 1789 iter_size = (sb->bucket_size / sb->block_size + 1) * 1790 sizeof(struct btree_iter_set); 1791 1792 if (!(c->devices = kcalloc(c->nr_uuids, sizeof(void *), GFP_KERNEL)) || 1793 mempool_init_slab_pool(&c->search, 32, bch_search_cache) || 1794 mempool_init_kmalloc_pool(&c->bio_meta, 2, 1795 sizeof(struct bbio) + sizeof(struct bio_vec) * 1796 bucket_pages(c)) || 1797 mempool_init_kmalloc_pool(&c->fill_iter, 1, iter_size) || 1798 bioset_init(&c->bio_split, 4, offsetof(struct bbio, bio), 1799 BIOSET_NEED_BVECS|BIOSET_NEED_RESCUER) || 1800 !(c->uuids = alloc_bucket_pages(GFP_KERNEL, c)) || 1801 !(c->moving_gc_wq = alloc_workqueue("bcache_gc", 1802 WQ_MEM_RECLAIM, 0)) || 1803 bch_journal_alloc(c) || 1804 bch_btree_cache_alloc(c) || 1805 bch_open_buckets_alloc(c) || 1806 bch_bset_sort_state_init(&c->sort, ilog2(c->btree_pages))) 1807 goto err; 1808 1809 c->congested_read_threshold_us = 2000; 1810 c->congested_write_threshold_us = 20000; 1811 c->error_limit = DEFAULT_IO_ERROR_LIMIT; 1812 WARN_ON(test_and_clear_bit(CACHE_SET_IO_DISABLE, &c->flags)); 1813 1814 return c; 1815 err: 1816 bch_cache_set_unregister(c); 1817 return NULL; 1818 } 1819 1820 static int run_cache_set(struct cache_set *c) 1821 { 1822 const char *err = "cannot allocate memory"; 1823 struct cached_dev *dc, *t; 1824 struct cache *ca; 1825 struct closure cl; 1826 unsigned int i; 1827 LIST_HEAD(journal); 1828 struct journal_replay *l; 1829 1830 closure_init_stack(&cl); 1831 1832 for_each_cache(ca, c, i) 1833 c->nbuckets += ca->sb.nbuckets; 1834 set_gc_sectors(c); 1835 1836 if (CACHE_SYNC(&c->sb)) { 1837 struct bkey *k; 1838 struct jset *j; 1839 1840 err = "cannot allocate memory for journal"; 1841 if (bch_journal_read(c, &journal)) 1842 goto err; 1843 1844 pr_debug("btree_journal_read() done"); 1845 1846 err = "no journal entries found"; 1847 if (list_empty(&journal)) 1848 goto err; 1849 1850 j = &list_entry(journal.prev, struct journal_replay, list)->j; 1851 1852 err = "IO error reading priorities"; 1853 for_each_cache(ca, c, i) 1854 prio_read(ca, j->prio_bucket[ca->sb.nr_this_dev]); 1855 1856 /* 1857 * If prio_read() fails it'll call cache_set_error and we'll 1858 * tear everything down right away, but if we perhaps checked 1859 * sooner we could avoid journal replay. 1860 */ 1861 1862 k = &j->btree_root; 1863 1864 err = "bad btree root"; 1865 if (__bch_btree_ptr_invalid(c, k)) 1866 goto err; 1867 1868 err = "error reading btree root"; 1869 c->root = bch_btree_node_get(c, NULL, k, 1870 j->btree_level, 1871 true, NULL); 1872 if (IS_ERR_OR_NULL(c->root)) 1873 goto err; 1874 1875 list_del_init(&c->root->list); 1876 rw_unlock(true, c->root); 1877 1878 err = uuid_read(c, j, &cl); 1879 if (err) 1880 goto err; 1881 1882 err = "error in recovery"; 1883 if (bch_btree_check(c)) 1884 goto err; 1885 1886 /* 1887 * bch_btree_check() may occupy too much system memory which 1888 * has negative effects to user space application (e.g. data 1889 * base) performance. Shrink the mca cache memory proactively 1890 * here to avoid competing memory with user space workloads.. 1891 */ 1892 if (!c->shrinker_disabled) { 1893 struct shrink_control sc; 1894 1895 sc.gfp_mask = GFP_KERNEL; 1896 sc.nr_to_scan = c->btree_cache_used * c->btree_pages; 1897 /* first run to clear b->accessed tag */ 1898 c->shrink.scan_objects(&c->shrink, &sc); 1899 /* second run to reap non-accessed nodes */ 1900 c->shrink.scan_objects(&c->shrink, &sc); 1901 } 1902 1903 bch_journal_mark(c, &journal); 1904 bch_initial_gc_finish(c); 1905 pr_debug("btree_check() done"); 1906 1907 /* 1908 * bcache_journal_next() can't happen sooner, or 1909 * btree_gc_finish() will give spurious errors about last_gc > 1910 * gc_gen - this is a hack but oh well. 1911 */ 1912 bch_journal_next(&c->journal); 1913 1914 err = "error starting allocator thread"; 1915 for_each_cache(ca, c, i) 1916 if (bch_cache_allocator_start(ca)) 1917 goto err; 1918 1919 /* 1920 * First place it's safe to allocate: btree_check() and 1921 * btree_gc_finish() have to run before we have buckets to 1922 * allocate, and bch_bucket_alloc_set() might cause a journal 1923 * entry to be written so bcache_journal_next() has to be called 1924 * first. 1925 * 1926 * If the uuids were in the old format we have to rewrite them 1927 * before the next journal entry is written: 1928 */ 1929 if (j->version < BCACHE_JSET_VERSION_UUID) 1930 __uuid_write(c); 1931 1932 err = "bcache: replay journal failed"; 1933 if (bch_journal_replay(c, &journal)) 1934 goto err; 1935 } else { 1936 pr_notice("invalidating existing data"); 1937 1938 for_each_cache(ca, c, i) { 1939 unsigned int j; 1940 1941 ca->sb.keys = clamp_t(int, ca->sb.nbuckets >> 7, 1942 2, SB_JOURNAL_BUCKETS); 1943 1944 for (j = 0; j < ca->sb.keys; j++) 1945 ca->sb.d[j] = ca->sb.first_bucket + j; 1946 } 1947 1948 bch_initial_gc_finish(c); 1949 1950 err = "error starting allocator thread"; 1951 for_each_cache(ca, c, i) 1952 if (bch_cache_allocator_start(ca)) 1953 goto err; 1954 1955 mutex_lock(&c->bucket_lock); 1956 for_each_cache(ca, c, i) 1957 bch_prio_write(ca); 1958 mutex_unlock(&c->bucket_lock); 1959 1960 err = "cannot allocate new UUID bucket"; 1961 if (__uuid_write(c)) 1962 goto err; 1963 1964 err = "cannot allocate new btree root"; 1965 c->root = __bch_btree_node_alloc(c, NULL, 0, true, NULL); 1966 if (IS_ERR_OR_NULL(c->root)) 1967 goto err; 1968 1969 mutex_lock(&c->root->write_lock); 1970 bkey_copy_key(&c->root->key, &MAX_KEY); 1971 bch_btree_node_write(c->root, &cl); 1972 mutex_unlock(&c->root->write_lock); 1973 1974 bch_btree_set_root(c->root); 1975 rw_unlock(true, c->root); 1976 1977 /* 1978 * We don't want to write the first journal entry until 1979 * everything is set up - fortunately journal entries won't be 1980 * written until the SET_CACHE_SYNC() here: 1981 */ 1982 SET_CACHE_SYNC(&c->sb, true); 1983 1984 bch_journal_next(&c->journal); 1985 bch_journal_meta(c, &cl); 1986 } 1987 1988 err = "error starting gc thread"; 1989 if (bch_gc_thread_start(c)) 1990 goto err; 1991 1992 closure_sync(&cl); 1993 c->sb.last_mount = (u32)ktime_get_real_seconds(); 1994 bcache_write_super(c); 1995 1996 list_for_each_entry_safe(dc, t, &uncached_devices, list) 1997 bch_cached_dev_attach(dc, c, NULL); 1998 1999 flash_devs_run(c); 2000 2001 set_bit(CACHE_SET_RUNNING, &c->flags); 2002 return 0; 2003 err: 2004 while (!list_empty(&journal)) { 2005 l = list_first_entry(&journal, struct journal_replay, list); 2006 list_del(&l->list); 2007 kfree(l); 2008 } 2009 2010 closure_sync(&cl); 2011 2012 bch_cache_set_error(c, "%s", err); 2013 2014 return -EIO; 2015 } 2016 2017 static bool can_attach_cache(struct cache *ca, struct cache_set *c) 2018 { 2019 return ca->sb.block_size == c->sb.block_size && 2020 ca->sb.bucket_size == c->sb.bucket_size && 2021 ca->sb.nr_in_set == c->sb.nr_in_set; 2022 } 2023 2024 static const char *register_cache_set(struct cache *ca) 2025 { 2026 char buf[12]; 2027 const char *err = "cannot allocate memory"; 2028 struct cache_set *c; 2029 2030 list_for_each_entry(c, &bch_cache_sets, list) 2031 if (!memcmp(c->sb.set_uuid, ca->sb.set_uuid, 16)) { 2032 if (c->cache[ca->sb.nr_this_dev]) 2033 return "duplicate cache set member"; 2034 2035 if (!can_attach_cache(ca, c)) 2036 return "cache sb does not match set"; 2037 2038 if (!CACHE_SYNC(&ca->sb)) 2039 SET_CACHE_SYNC(&c->sb, false); 2040 2041 goto found; 2042 } 2043 2044 c = bch_cache_set_alloc(&ca->sb); 2045 if (!c) 2046 return err; 2047 2048 err = "error creating kobject"; 2049 if (kobject_add(&c->kobj, bcache_kobj, "%pU", c->sb.set_uuid) || 2050 kobject_add(&c->internal, &c->kobj, "internal")) 2051 goto err; 2052 2053 if (bch_cache_accounting_add_kobjs(&c->accounting, &c->kobj)) 2054 goto err; 2055 2056 bch_debug_init_cache_set(c); 2057 2058 list_add(&c->list, &bch_cache_sets); 2059 found: 2060 sprintf(buf, "cache%i", ca->sb.nr_this_dev); 2061 if (sysfs_create_link(&ca->kobj, &c->kobj, "set") || 2062 sysfs_create_link(&c->kobj, &ca->kobj, buf)) 2063 goto err; 2064 2065 if (ca->sb.seq > c->sb.seq) { 2066 c->sb.version = ca->sb.version; 2067 memcpy(c->sb.set_uuid, ca->sb.set_uuid, 16); 2068 c->sb.flags = ca->sb.flags; 2069 c->sb.seq = ca->sb.seq; 2070 pr_debug("set version = %llu", c->sb.version); 2071 } 2072 2073 kobject_get(&ca->kobj); 2074 ca->set = c; 2075 ca->set->cache[ca->sb.nr_this_dev] = ca; 2076 c->cache_by_alloc[c->caches_loaded++] = ca; 2077 2078 if (c->caches_loaded == c->sb.nr_in_set) { 2079 err = "failed to run cache set"; 2080 if (run_cache_set(c) < 0) 2081 goto err; 2082 } 2083 2084 return NULL; 2085 err: 2086 bch_cache_set_unregister(c); 2087 return err; 2088 } 2089 2090 /* Cache device */ 2091 2092 /* When ca->kobj released */ 2093 void bch_cache_release(struct kobject *kobj) 2094 { 2095 struct cache *ca = container_of(kobj, struct cache, kobj); 2096 unsigned int i; 2097 2098 if (ca->set) { 2099 BUG_ON(ca->set->cache[ca->sb.nr_this_dev] != ca); 2100 ca->set->cache[ca->sb.nr_this_dev] = NULL; 2101 } 2102 2103 free_pages((unsigned long) ca->disk_buckets, ilog2(bucket_pages(ca))); 2104 kfree(ca->prio_buckets); 2105 vfree(ca->buckets); 2106 2107 free_heap(&ca->heap); 2108 free_fifo(&ca->free_inc); 2109 2110 for (i = 0; i < RESERVE_NR; i++) 2111 free_fifo(&ca->free[i]); 2112 2113 if (ca->sb_bio.bi_inline_vecs[0].bv_page) 2114 put_page(bio_first_page_all(&ca->sb_bio)); 2115 2116 if (!IS_ERR_OR_NULL(ca->bdev)) 2117 blkdev_put(ca->bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL); 2118 2119 kfree(ca); 2120 module_put(THIS_MODULE); 2121 } 2122 2123 static int cache_alloc(struct cache *ca) 2124 { 2125 size_t free; 2126 size_t btree_buckets; 2127 struct bucket *b; 2128 int ret = -ENOMEM; 2129 const char *err = NULL; 2130 2131 __module_get(THIS_MODULE); 2132 kobject_init(&ca->kobj, &bch_cache_ktype); 2133 2134 bio_init(&ca->journal.bio, ca->journal.bio.bi_inline_vecs, 8); 2135 2136 /* 2137 * when ca->sb.njournal_buckets is not zero, journal exists, 2138 * and in bch_journal_replay(), tree node may split, 2139 * so bucket of RESERVE_BTREE type is needed, 2140 * the worst situation is all journal buckets are valid journal, 2141 * and all the keys need to replay, 2142 * so the number of RESERVE_BTREE type buckets should be as much 2143 * as journal buckets 2144 */ 2145 btree_buckets = ca->sb.njournal_buckets ?: 8; 2146 free = roundup_pow_of_two(ca->sb.nbuckets) >> 10; 2147 if (!free) { 2148 ret = -EPERM; 2149 err = "ca->sb.nbuckets is too small"; 2150 goto err_free; 2151 } 2152 2153 if (!init_fifo(&ca->free[RESERVE_BTREE], btree_buckets, 2154 GFP_KERNEL)) { 2155 err = "ca->free[RESERVE_BTREE] alloc failed"; 2156 goto err_btree_alloc; 2157 } 2158 2159 if (!init_fifo_exact(&ca->free[RESERVE_PRIO], prio_buckets(ca), 2160 GFP_KERNEL)) { 2161 err = "ca->free[RESERVE_PRIO] alloc failed"; 2162 goto err_prio_alloc; 2163 } 2164 2165 if (!init_fifo(&ca->free[RESERVE_MOVINGGC], free, GFP_KERNEL)) { 2166 err = "ca->free[RESERVE_MOVINGGC] alloc failed"; 2167 goto err_movinggc_alloc; 2168 } 2169 2170 if (!init_fifo(&ca->free[RESERVE_NONE], free, GFP_KERNEL)) { 2171 err = "ca->free[RESERVE_NONE] alloc failed"; 2172 goto err_none_alloc; 2173 } 2174 2175 if (!init_fifo(&ca->free_inc, free << 2, GFP_KERNEL)) { 2176 err = "ca->free_inc alloc failed"; 2177 goto err_free_inc_alloc; 2178 } 2179 2180 if (!init_heap(&ca->heap, free << 3, GFP_KERNEL)) { 2181 err = "ca->heap alloc failed"; 2182 goto err_heap_alloc; 2183 } 2184 2185 ca->buckets = vzalloc(array_size(sizeof(struct bucket), 2186 ca->sb.nbuckets)); 2187 if (!ca->buckets) { 2188 err = "ca->buckets alloc failed"; 2189 goto err_buckets_alloc; 2190 } 2191 2192 ca->prio_buckets = kzalloc(array3_size(sizeof(uint64_t), 2193 prio_buckets(ca), 2), 2194 GFP_KERNEL); 2195 if (!ca->prio_buckets) { 2196 err = "ca->prio_buckets alloc failed"; 2197 goto err_prio_buckets_alloc; 2198 } 2199 2200 ca->disk_buckets = alloc_bucket_pages(GFP_KERNEL, ca); 2201 if (!ca->disk_buckets) { 2202 err = "ca->disk_buckets alloc failed"; 2203 goto err_disk_buckets_alloc; 2204 } 2205 2206 ca->prio_last_buckets = ca->prio_buckets + prio_buckets(ca); 2207 2208 for_each_bucket(b, ca) 2209 atomic_set(&b->pin, 0); 2210 return 0; 2211 2212 err_disk_buckets_alloc: 2213 kfree(ca->prio_buckets); 2214 err_prio_buckets_alloc: 2215 vfree(ca->buckets); 2216 err_buckets_alloc: 2217 free_heap(&ca->heap); 2218 err_heap_alloc: 2219 free_fifo(&ca->free_inc); 2220 err_free_inc_alloc: 2221 free_fifo(&ca->free[RESERVE_NONE]); 2222 err_none_alloc: 2223 free_fifo(&ca->free[RESERVE_MOVINGGC]); 2224 err_movinggc_alloc: 2225 free_fifo(&ca->free[RESERVE_PRIO]); 2226 err_prio_alloc: 2227 free_fifo(&ca->free[RESERVE_BTREE]); 2228 err_btree_alloc: 2229 err_free: 2230 module_put(THIS_MODULE); 2231 if (err) 2232 pr_notice("error %s: %s", ca->cache_dev_name, err); 2233 return ret; 2234 } 2235 2236 static int register_cache(struct cache_sb *sb, struct page *sb_page, 2237 struct block_device *bdev, struct cache *ca) 2238 { 2239 const char *err = NULL; /* must be set for any error case */ 2240 int ret = 0; 2241 2242 bdevname(bdev, ca->cache_dev_name); 2243 memcpy(&ca->sb, sb, sizeof(struct cache_sb)); 2244 ca->bdev = bdev; 2245 ca->bdev->bd_holder = ca; 2246 2247 bio_init(&ca->sb_bio, ca->sb_bio.bi_inline_vecs, 1); 2248 bio_first_bvec_all(&ca->sb_bio)->bv_page = sb_page; 2249 get_page(sb_page); 2250 2251 if (blk_queue_discard(bdev_get_queue(bdev))) 2252 ca->discard = CACHE_DISCARD(&ca->sb); 2253 2254 ret = cache_alloc(ca); 2255 if (ret != 0) { 2256 /* 2257 * If we failed here, it means ca->kobj is not initialized yet, 2258 * kobject_put() won't be called and there is no chance to 2259 * call blkdev_put() to bdev in bch_cache_release(). So we 2260 * explicitly call blkdev_put() here. 2261 */ 2262 blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL); 2263 if (ret == -ENOMEM) 2264 err = "cache_alloc(): -ENOMEM"; 2265 else if (ret == -EPERM) 2266 err = "cache_alloc(): cache device is too small"; 2267 else 2268 err = "cache_alloc(): unknown error"; 2269 goto err; 2270 } 2271 2272 if (kobject_add(&ca->kobj, 2273 &part_to_dev(bdev->bd_part)->kobj, 2274 "bcache")) { 2275 err = "error calling kobject_add"; 2276 ret = -ENOMEM; 2277 goto out; 2278 } 2279 2280 mutex_lock(&bch_register_lock); 2281 err = register_cache_set(ca); 2282 mutex_unlock(&bch_register_lock); 2283 2284 if (err) { 2285 ret = -ENODEV; 2286 goto out; 2287 } 2288 2289 pr_info("registered cache device %s", ca->cache_dev_name); 2290 2291 out: 2292 kobject_put(&ca->kobj); 2293 2294 err: 2295 if (err) 2296 pr_notice("error %s: %s", ca->cache_dev_name, err); 2297 2298 return ret; 2299 } 2300 2301 /* Global interfaces/init */ 2302 2303 static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr, 2304 const char *buffer, size_t size); 2305 static ssize_t bch_pending_bdevs_cleanup(struct kobject *k, 2306 struct kobj_attribute *attr, 2307 const char *buffer, size_t size); 2308 2309 kobj_attribute_write(register, register_bcache); 2310 kobj_attribute_write(register_quiet, register_bcache); 2311 kobj_attribute_write(pendings_cleanup, bch_pending_bdevs_cleanup); 2312 2313 static bool bch_is_open_backing(struct block_device *bdev) 2314 { 2315 struct cache_set *c, *tc; 2316 struct cached_dev *dc, *t; 2317 2318 list_for_each_entry_safe(c, tc, &bch_cache_sets, list) 2319 list_for_each_entry_safe(dc, t, &c->cached_devs, list) 2320 if (dc->bdev == bdev) 2321 return true; 2322 list_for_each_entry_safe(dc, t, &uncached_devices, list) 2323 if (dc->bdev == bdev) 2324 return true; 2325 return false; 2326 } 2327 2328 static bool bch_is_open_cache(struct block_device *bdev) 2329 { 2330 struct cache_set *c, *tc; 2331 struct cache *ca; 2332 unsigned int i; 2333 2334 list_for_each_entry_safe(c, tc, &bch_cache_sets, list) 2335 for_each_cache(ca, c, i) 2336 if (ca->bdev == bdev) 2337 return true; 2338 return false; 2339 } 2340 2341 static bool bch_is_open(struct block_device *bdev) 2342 { 2343 return bch_is_open_cache(bdev) || bch_is_open_backing(bdev); 2344 } 2345 2346 static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr, 2347 const char *buffer, size_t size) 2348 { 2349 ssize_t ret = -EINVAL; 2350 const char *err = "cannot allocate memory"; 2351 char *path = NULL; 2352 struct cache_sb *sb = NULL; 2353 struct block_device *bdev = NULL; 2354 struct page *sb_page = NULL; 2355 2356 if (!try_module_get(THIS_MODULE)) 2357 return -EBUSY; 2358 2359 /* For latest state of bcache_is_reboot */ 2360 smp_mb(); 2361 if (bcache_is_reboot) 2362 return -EBUSY; 2363 2364 path = kstrndup(buffer, size, GFP_KERNEL); 2365 if (!path) 2366 goto err; 2367 2368 sb = kmalloc(sizeof(struct cache_sb), GFP_KERNEL); 2369 if (!sb) 2370 goto err; 2371 2372 err = "failed to open device"; 2373 bdev = blkdev_get_by_path(strim(path), 2374 FMODE_READ|FMODE_WRITE|FMODE_EXCL, 2375 sb); 2376 if (IS_ERR(bdev)) { 2377 if (bdev == ERR_PTR(-EBUSY)) { 2378 bdev = lookup_bdev(strim(path)); 2379 mutex_lock(&bch_register_lock); 2380 if (!IS_ERR(bdev) && bch_is_open(bdev)) 2381 err = "device already registered"; 2382 else 2383 err = "device busy"; 2384 mutex_unlock(&bch_register_lock); 2385 if (!IS_ERR(bdev)) 2386 bdput(bdev); 2387 if (attr == &ksysfs_register_quiet) 2388 goto quiet_out; 2389 } 2390 goto err; 2391 } 2392 2393 err = "failed to set blocksize"; 2394 if (set_blocksize(bdev, 4096)) 2395 goto err_close; 2396 2397 err = read_super(sb, bdev, &sb_page); 2398 if (err) 2399 goto err_close; 2400 2401 err = "failed to register device"; 2402 if (SB_IS_BDEV(sb)) { 2403 struct cached_dev *dc = kzalloc(sizeof(*dc), GFP_KERNEL); 2404 2405 if (!dc) 2406 goto err_close; 2407 2408 mutex_lock(&bch_register_lock); 2409 ret = register_bdev(sb, sb_page, bdev, dc); 2410 mutex_unlock(&bch_register_lock); 2411 /* blkdev_put() will be called in cached_dev_free() */ 2412 if (ret < 0) 2413 goto err; 2414 } else { 2415 struct cache *ca = kzalloc(sizeof(*ca), GFP_KERNEL); 2416 2417 if (!ca) 2418 goto err_close; 2419 2420 /* blkdev_put() will be called in bch_cache_release() */ 2421 if (register_cache(sb, sb_page, bdev, ca) != 0) 2422 goto err; 2423 } 2424 quiet_out: 2425 ret = size; 2426 out: 2427 if (sb_page) 2428 put_page(sb_page); 2429 kfree(sb); 2430 kfree(path); 2431 module_put(THIS_MODULE); 2432 return ret; 2433 2434 err_close: 2435 blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL); 2436 err: 2437 pr_info("error %s: %s", path, err); 2438 goto out; 2439 } 2440 2441 2442 struct pdev { 2443 struct list_head list; 2444 struct cached_dev *dc; 2445 }; 2446 2447 static ssize_t bch_pending_bdevs_cleanup(struct kobject *k, 2448 struct kobj_attribute *attr, 2449 const char *buffer, 2450 size_t size) 2451 { 2452 LIST_HEAD(pending_devs); 2453 ssize_t ret = size; 2454 struct cached_dev *dc, *tdc; 2455 struct pdev *pdev, *tpdev; 2456 struct cache_set *c, *tc; 2457 2458 mutex_lock(&bch_register_lock); 2459 list_for_each_entry_safe(dc, tdc, &uncached_devices, list) { 2460 pdev = kmalloc(sizeof(struct pdev), GFP_KERNEL); 2461 if (!pdev) 2462 break; 2463 pdev->dc = dc; 2464 list_add(&pdev->list, &pending_devs); 2465 } 2466 2467 list_for_each_entry_safe(pdev, tpdev, &pending_devs, list) { 2468 list_for_each_entry_safe(c, tc, &bch_cache_sets, list) { 2469 char *pdev_set_uuid = pdev->dc->sb.set_uuid; 2470 char *set_uuid = c->sb.uuid; 2471 2472 if (!memcmp(pdev_set_uuid, set_uuid, 16)) { 2473 list_del(&pdev->list); 2474 kfree(pdev); 2475 break; 2476 } 2477 } 2478 } 2479 mutex_unlock(&bch_register_lock); 2480 2481 list_for_each_entry_safe(pdev, tpdev, &pending_devs, list) { 2482 pr_info("delete pdev %p", pdev); 2483 list_del(&pdev->list); 2484 bcache_device_stop(&pdev->dc->disk); 2485 kfree(pdev); 2486 } 2487 2488 return ret; 2489 } 2490 2491 static int bcache_reboot(struct notifier_block *n, unsigned long code, void *x) 2492 { 2493 if (bcache_is_reboot) 2494 return NOTIFY_DONE; 2495 2496 if (code == SYS_DOWN || 2497 code == SYS_HALT || 2498 code == SYS_POWER_OFF) { 2499 DEFINE_WAIT(wait); 2500 unsigned long start = jiffies; 2501 bool stopped = false; 2502 2503 struct cache_set *c, *tc; 2504 struct cached_dev *dc, *tdc; 2505 2506 mutex_lock(&bch_register_lock); 2507 2508 if (bcache_is_reboot) 2509 goto out; 2510 2511 /* New registration is rejected since now */ 2512 bcache_is_reboot = true; 2513 /* 2514 * Make registering caller (if there is) on other CPU 2515 * core know bcache_is_reboot set to true earlier 2516 */ 2517 smp_mb(); 2518 2519 if (list_empty(&bch_cache_sets) && 2520 list_empty(&uncached_devices)) 2521 goto out; 2522 2523 mutex_unlock(&bch_register_lock); 2524 2525 pr_info("Stopping all devices:"); 2526 2527 /* 2528 * The reason bch_register_lock is not held to call 2529 * bch_cache_set_stop() and bcache_device_stop() is to 2530 * avoid potential deadlock during reboot, because cache 2531 * set or bcache device stopping process will acqurie 2532 * bch_register_lock too. 2533 * 2534 * We are safe here because bcache_is_reboot sets to 2535 * true already, register_bcache() will reject new 2536 * registration now. bcache_is_reboot also makes sure 2537 * bcache_reboot() won't be re-entered on by other thread, 2538 * so there is no race in following list iteration by 2539 * list_for_each_entry_safe(). 2540 */ 2541 list_for_each_entry_safe(c, tc, &bch_cache_sets, list) 2542 bch_cache_set_stop(c); 2543 2544 list_for_each_entry_safe(dc, tdc, &uncached_devices, list) 2545 bcache_device_stop(&dc->disk); 2546 2547 2548 /* 2549 * Give an early chance for other kthreads and 2550 * kworkers to stop themselves 2551 */ 2552 schedule(); 2553 2554 /* What's a condition variable? */ 2555 while (1) { 2556 long timeout = start + 10 * HZ - jiffies; 2557 2558 mutex_lock(&bch_register_lock); 2559 stopped = list_empty(&bch_cache_sets) && 2560 list_empty(&uncached_devices); 2561 2562 if (timeout < 0 || stopped) 2563 break; 2564 2565 prepare_to_wait(&unregister_wait, &wait, 2566 TASK_UNINTERRUPTIBLE); 2567 2568 mutex_unlock(&bch_register_lock); 2569 schedule_timeout(timeout); 2570 } 2571 2572 finish_wait(&unregister_wait, &wait); 2573 2574 if (stopped) 2575 pr_info("All devices stopped"); 2576 else 2577 pr_notice("Timeout waiting for devices to be closed"); 2578 out: 2579 mutex_unlock(&bch_register_lock); 2580 } 2581 2582 return NOTIFY_DONE; 2583 } 2584 2585 static struct notifier_block reboot = { 2586 .notifier_call = bcache_reboot, 2587 .priority = INT_MAX, /* before any real devices */ 2588 }; 2589 2590 static void bcache_exit(void) 2591 { 2592 bch_debug_exit(); 2593 bch_request_exit(); 2594 if (bcache_kobj) 2595 kobject_put(bcache_kobj); 2596 if (bcache_wq) 2597 destroy_workqueue(bcache_wq); 2598 if (bch_journal_wq) 2599 destroy_workqueue(bch_journal_wq); 2600 2601 if (bcache_major) 2602 unregister_blkdev(bcache_major, "bcache"); 2603 unregister_reboot_notifier(&reboot); 2604 mutex_destroy(&bch_register_lock); 2605 } 2606 2607 /* Check and fixup module parameters */ 2608 static void check_module_parameters(void) 2609 { 2610 if (bch_cutoff_writeback_sync == 0) 2611 bch_cutoff_writeback_sync = CUTOFF_WRITEBACK_SYNC; 2612 else if (bch_cutoff_writeback_sync > CUTOFF_WRITEBACK_SYNC_MAX) { 2613 pr_warn("set bch_cutoff_writeback_sync (%u) to max value %u", 2614 bch_cutoff_writeback_sync, CUTOFF_WRITEBACK_SYNC_MAX); 2615 bch_cutoff_writeback_sync = CUTOFF_WRITEBACK_SYNC_MAX; 2616 } 2617 2618 if (bch_cutoff_writeback == 0) 2619 bch_cutoff_writeback = CUTOFF_WRITEBACK; 2620 else if (bch_cutoff_writeback > CUTOFF_WRITEBACK_MAX) { 2621 pr_warn("set bch_cutoff_writeback (%u) to max value %u", 2622 bch_cutoff_writeback, CUTOFF_WRITEBACK_MAX); 2623 bch_cutoff_writeback = CUTOFF_WRITEBACK_MAX; 2624 } 2625 2626 if (bch_cutoff_writeback > bch_cutoff_writeback_sync) { 2627 pr_warn("set bch_cutoff_writeback (%u) to %u", 2628 bch_cutoff_writeback, bch_cutoff_writeback_sync); 2629 bch_cutoff_writeback = bch_cutoff_writeback_sync; 2630 } 2631 } 2632 2633 static int __init bcache_init(void) 2634 { 2635 static const struct attribute *files[] = { 2636 &ksysfs_register.attr, 2637 &ksysfs_register_quiet.attr, 2638 &ksysfs_pendings_cleanup.attr, 2639 NULL 2640 }; 2641 2642 check_module_parameters(); 2643 2644 mutex_init(&bch_register_lock); 2645 init_waitqueue_head(&unregister_wait); 2646 register_reboot_notifier(&reboot); 2647 2648 bcache_major = register_blkdev(0, "bcache"); 2649 if (bcache_major < 0) { 2650 unregister_reboot_notifier(&reboot); 2651 mutex_destroy(&bch_register_lock); 2652 return bcache_major; 2653 } 2654 2655 bcache_wq = alloc_workqueue("bcache", WQ_MEM_RECLAIM, 0); 2656 if (!bcache_wq) 2657 goto err; 2658 2659 bch_journal_wq = alloc_workqueue("bch_journal", WQ_MEM_RECLAIM, 0); 2660 if (!bch_journal_wq) 2661 goto err; 2662 2663 bcache_kobj = kobject_create_and_add("bcache", fs_kobj); 2664 if (!bcache_kobj) 2665 goto err; 2666 2667 if (bch_request_init() || 2668 sysfs_create_files(bcache_kobj, files)) 2669 goto err; 2670 2671 bch_debug_init(); 2672 closure_debug_init(); 2673 2674 bcache_is_reboot = false; 2675 2676 return 0; 2677 err: 2678 bcache_exit(); 2679 return -ENOMEM; 2680 } 2681 2682 /* 2683 * Module hooks 2684 */ 2685 module_exit(bcache_exit); 2686 module_init(bcache_init); 2687 2688 module_param(bch_cutoff_writeback, uint, 0); 2689 MODULE_PARM_DESC(bch_cutoff_writeback, "threshold to cutoff writeback"); 2690 2691 module_param(bch_cutoff_writeback_sync, uint, 0); 2692 MODULE_PARM_DESC(bch_cutoff_writeback_sync, "hard threshold to cutoff writeback"); 2693 2694 MODULE_DESCRIPTION("Bcache: a Linux block layer cache"); 2695 MODULE_AUTHOR("Kent Overstreet <kent.overstreet@gmail.com>"); 2696 MODULE_LICENSE("GPL"); 2697