1#ifndef _BCACHE_H 2#define _BCACHE_H 3 4/* 5 * SOME HIGH LEVEL CODE DOCUMENTATION: 6 * 7 * Bcache mostly works with cache sets, cache devices, and backing devices. 8 * 9 * Support for multiple cache devices hasn't quite been finished off yet, but 10 * it's about 95% plumbed through. A cache set and its cache devices is sort of 11 * like a md raid array and its component devices. Most of the code doesn't care 12 * about individual cache devices, the main abstraction is the cache set. 13 * 14 * Multiple cache devices is intended to give us the ability to mirror dirty 15 * cached data and metadata, without mirroring clean cached data. 16 * 17 * Backing devices are different, in that they have a lifetime independent of a 18 * cache set. When you register a newly formatted backing device it'll come up 19 * in passthrough mode, and then you can attach and detach a backing device from 20 * a cache set at runtime - while it's mounted and in use. Detaching implicitly 21 * invalidates any cached data for that backing device. 22 * 23 * A cache set can have multiple (many) backing devices attached to it. 24 * 25 * There's also flash only volumes - this is the reason for the distinction 26 * between struct cached_dev and struct bcache_device. A flash only volume 27 * works much like a bcache device that has a backing device, except the 28 * "cached" data is always dirty. The end result is that we get thin 29 * provisioning with very little additional code. 30 * 31 * Flash only volumes work but they're not production ready because the moving 32 * garbage collector needs more work. More on that later. 33 * 34 * BUCKETS/ALLOCATION: 35 * 36 * Bcache is primarily designed for caching, which means that in normal 37 * operation all of our available space will be allocated. Thus, we need an 38 * efficient way of deleting things from the cache so we can write new things to 39 * it. 40 * 41 * To do this, we first divide the cache device up into buckets. A bucket is the 42 * unit of allocation; they're typically around 1 mb - anywhere from 128k to 2M+ 43 * works efficiently. 44 * 45 * Each bucket has a 16 bit priority, and an 8 bit generation associated with 46 * it. The gens and priorities for all the buckets are stored contiguously and 47 * packed on disk (in a linked list of buckets - aside from the superblock, all 48 * of bcache's metadata is stored in buckets). 49 * 50 * The priority is used to implement an LRU. We reset a bucket's priority when 51 * we allocate it or on cache it, and every so often we decrement the priority 52 * of each bucket. It could be used to implement something more sophisticated, 53 * if anyone ever gets around to it. 54 * 55 * The generation is used for invalidating buckets. Each pointer also has an 8 56 * bit generation embedded in it; for a pointer to be considered valid, its gen 57 * must match the gen of the bucket it points into. Thus, to reuse a bucket all 58 * we have to do is increment its gen (and write its new gen to disk; we batch 59 * this up). 60 * 61 * Bcache is entirely COW - we never write twice to a bucket, even buckets that 62 * contain metadata (including btree nodes). 63 * 64 * THE BTREE: 65 * 66 * Bcache is in large part design around the btree. 67 * 68 * At a high level, the btree is just an index of key -> ptr tuples. 69 * 70 * Keys represent extents, and thus have a size field. Keys also have a variable 71 * number of pointers attached to them (potentially zero, which is handy for 72 * invalidating the cache). 73 * 74 * The key itself is an inode:offset pair. The inode number corresponds to a 75 * backing device or a flash only volume. The offset is the ending offset of the 76 * extent within the inode - not the starting offset; this makes lookups 77 * slightly more convenient. 78 * 79 * Pointers contain the cache device id, the offset on that device, and an 8 bit 80 * generation number. More on the gen later. 81 * 82 * Index lookups are not fully abstracted - cache lookups in particular are 83 * still somewhat mixed in with the btree code, but things are headed in that 84 * direction. 85 * 86 * Updates are fairly well abstracted, though. There are two different ways of 87 * updating the btree; insert and replace. 88 * 89 * BTREE_INSERT will just take a list of keys and insert them into the btree - 90 * overwriting (possibly only partially) any extents they overlap with. This is 91 * used to update the index after a write. 92 * 93 * BTREE_REPLACE is really cmpxchg(); it inserts a key into the btree iff it is 94 * overwriting a key that matches another given key. This is used for inserting 95 * data into the cache after a cache miss, and for background writeback, and for 96 * the moving garbage collector. 97 * 98 * There is no "delete" operation; deleting things from the index is 99 * accomplished by either by invalidating pointers (by incrementing a bucket's 100 * gen) or by inserting a key with 0 pointers - which will overwrite anything 101 * previously present at that location in the index. 102 * 103 * This means that there are always stale/invalid keys in the btree. They're 104 * filtered out by the code that iterates through a btree node, and removed when 105 * a btree node is rewritten. 106 * 107 * BTREE NODES: 108 * 109 * Our unit of allocation is a bucket, and we we can't arbitrarily allocate and 110 * free smaller than a bucket - so, that's how big our btree nodes are. 111 * 112 * (If buckets are really big we'll only use part of the bucket for a btree node 113 * - no less than 1/4th - but a bucket still contains no more than a single 114 * btree node. I'd actually like to change this, but for now we rely on the 115 * bucket's gen for deleting btree nodes when we rewrite/split a node.) 116 * 117 * Anyways, btree nodes are big - big enough to be inefficient with a textbook 118 * btree implementation. 119 * 120 * The way this is solved is that btree nodes are internally log structured; we 121 * can append new keys to an existing btree node without rewriting it. This 122 * means each set of keys we write is sorted, but the node is not. 123 * 124 * We maintain this log structure in memory - keeping 1Mb of keys sorted would 125 * be expensive, and we have to distinguish between the keys we have written and 126 * the keys we haven't. So to do a lookup in a btree node, we have to search 127 * each sorted set. But we do merge written sets together lazily, so the cost of 128 * these extra searches is quite low (normally most of the keys in a btree node 129 * will be in one big set, and then there'll be one or two sets that are much 130 * smaller). 131 * 132 * This log structure makes bcache's btree more of a hybrid between a 133 * conventional btree and a compacting data structure, with some of the 134 * advantages of both. 135 * 136 * GARBAGE COLLECTION: 137 * 138 * We can't just invalidate any bucket - it might contain dirty data or 139 * metadata. If it once contained dirty data, other writes might overwrite it 140 * later, leaving no valid pointers into that bucket in the index. 141 * 142 * Thus, the primary purpose of garbage collection is to find buckets to reuse. 143 * It also counts how much valid data it each bucket currently contains, so that 144 * allocation can reuse buckets sooner when they've been mostly overwritten. 145 * 146 * It also does some things that are really internal to the btree 147 * implementation. If a btree node contains pointers that are stale by more than 148 * some threshold, it rewrites the btree node to avoid the bucket's generation 149 * wrapping around. It also merges adjacent btree nodes if they're empty enough. 150 * 151 * THE JOURNAL: 152 * 153 * Bcache's journal is not necessary for consistency; we always strictly 154 * order metadata writes so that the btree and everything else is consistent on 155 * disk in the event of an unclean shutdown, and in fact bcache had writeback 156 * caching (with recovery from unclean shutdown) before journalling was 157 * implemented. 158 * 159 * Rather, the journal is purely a performance optimization; we can't complete a 160 * write until we've updated the index on disk, otherwise the cache would be 161 * inconsistent in the event of an unclean shutdown. This means that without the 162 * journal, on random write workloads we constantly have to update all the leaf 163 * nodes in the btree, and those writes will be mostly empty (appending at most 164 * a few keys each) - highly inefficient in terms of amount of metadata writes, 165 * and it puts more strain on the various btree resorting/compacting code. 166 * 167 * The journal is just a log of keys we've inserted; on startup we just reinsert 168 * all the keys in the open journal entries. That means that when we're updating 169 * a node in the btree, we can wait until a 4k block of keys fills up before 170 * writing them out. 171 * 172 * For simplicity, we only journal updates to leaf nodes; updates to parent 173 * nodes are rare enough (since our leaf nodes are huge) that it wasn't worth 174 * the complexity to deal with journalling them (in particular, journal replay) 175 * - updates to non leaf nodes just happen synchronously (see btree_split()). 176 */ 177 178#define pr_fmt(fmt) "bcache: %s() " fmt "\n", __func__ 179 180#include <linux/bcache.h> 181#include <linux/bio.h> 182#include <linux/kobject.h> 183#include <linux/list.h> 184#include <linux/mutex.h> 185#include <linux/rbtree.h> 186#include <linux/rwsem.h> 187#include <linux/types.h> 188#include <linux/workqueue.h> 189 190#include "bset.h" 191#include "util.h" 192#include "closure.h" 193 194struct bucket { 195 atomic_t pin; 196 uint16_t prio; 197 uint8_t gen; 198 uint8_t last_gc; /* Most out of date gen in the btree */ 199 uint16_t gc_mark; /* Bitfield used by GC. See below for field */ 200}; 201 202/* 203 * I'd use bitfields for these, but I don't trust the compiler not to screw me 204 * as multiple threads touch struct bucket without locking 205 */ 206 207BITMASK(GC_MARK, struct bucket, gc_mark, 0, 2); 208#define GC_MARK_RECLAIMABLE 1 209#define GC_MARK_DIRTY 2 210#define GC_MARK_METADATA 3 211#define GC_SECTORS_USED_SIZE 13 212#define MAX_GC_SECTORS_USED (~(~0ULL << GC_SECTORS_USED_SIZE)) 213BITMASK(GC_SECTORS_USED, struct bucket, gc_mark, 2, GC_SECTORS_USED_SIZE); 214BITMASK(GC_MOVE, struct bucket, gc_mark, 15, 1); 215 216#include "journal.h" 217#include "stats.h" 218struct search; 219struct btree; 220struct keybuf; 221 222struct keybuf_key { 223 struct rb_node node; 224 BKEY_PADDED(key); 225 void *private; 226}; 227 228struct keybuf { 229 struct bkey last_scanned; 230 spinlock_t lock; 231 232 /* 233 * Beginning and end of range in rb tree - so that we can skip taking 234 * lock and checking the rb tree when we need to check for overlapping 235 * keys. 236 */ 237 struct bkey start; 238 struct bkey end; 239 240 struct rb_root keys; 241 242#define KEYBUF_NR 500 243 DECLARE_ARRAY_ALLOCATOR(struct keybuf_key, freelist, KEYBUF_NR); 244}; 245 246struct bio_split_pool { 247 struct bio_set *bio_split; 248 mempool_t *bio_split_hook; 249}; 250 251struct bio_split_hook { 252 struct closure cl; 253 struct bio_split_pool *p; 254 struct bio *bio; 255 bio_end_io_t *bi_end_io; 256 void *bi_private; 257}; 258 259struct bcache_device { 260 struct closure cl; 261 262 struct kobject kobj; 263 264 struct cache_set *c; 265 unsigned id; 266#define BCACHEDEVNAME_SIZE 12 267 char name[BCACHEDEVNAME_SIZE]; 268 269 struct gendisk *disk; 270 271 unsigned long flags; 272#define BCACHE_DEV_CLOSING 0 273#define BCACHE_DEV_DETACHING 1 274#define BCACHE_DEV_UNLINK_DONE 2 275 276 unsigned nr_stripes; 277 unsigned stripe_size; 278 atomic_t *stripe_sectors_dirty; 279 unsigned long *full_dirty_stripes; 280 281 unsigned long sectors_dirty_last; 282 long sectors_dirty_derivative; 283 284 struct bio_set *bio_split; 285 286 unsigned data_csum:1; 287 288 int (*cache_miss)(struct btree *, struct search *, 289 struct bio *, unsigned); 290 int (*ioctl) (struct bcache_device *, fmode_t, unsigned, unsigned long); 291 292 struct bio_split_pool bio_split_hook; 293}; 294 295struct io { 296 /* Used to track sequential IO so it can be skipped */ 297 struct hlist_node hash; 298 struct list_head lru; 299 300 unsigned long jiffies; 301 unsigned sequential; 302 sector_t last; 303}; 304 305struct cached_dev { 306 struct list_head list; 307 struct bcache_device disk; 308 struct block_device *bdev; 309 310 struct cache_sb sb; 311 struct bio sb_bio; 312 struct bio_vec sb_bv[1]; 313 struct closure sb_write; 314 struct semaphore sb_write_mutex; 315 316 /* Refcount on the cache set. Always nonzero when we're caching. */ 317 atomic_t count; 318 struct work_struct detach; 319 320 /* 321 * Device might not be running if it's dirty and the cache set hasn't 322 * showed up yet. 323 */ 324 atomic_t running; 325 326 /* 327 * Writes take a shared lock from start to finish; scanning for dirty 328 * data to refill the rb tree requires an exclusive lock. 329 */ 330 struct rw_semaphore writeback_lock; 331 332 /* 333 * Nonzero, and writeback has a refcount (d->count), iff there is dirty 334 * data in the cache. Protected by writeback_lock; must have an 335 * shared lock to set and exclusive lock to clear. 336 */ 337 atomic_t has_dirty; 338 339 struct bch_ratelimit writeback_rate; 340 struct delayed_work writeback_rate_update; 341 342 /* 343 * Internal to the writeback code, so read_dirty() can keep track of 344 * where it's at. 345 */ 346 sector_t last_read; 347 348 /* Limit number of writeback bios in flight */ 349 struct semaphore in_flight; 350 struct task_struct *writeback_thread; 351 352 struct keybuf writeback_keys; 353 354 /* For tracking sequential IO */ 355#define RECENT_IO_BITS 7 356#define RECENT_IO (1 << RECENT_IO_BITS) 357 struct io io[RECENT_IO]; 358 struct hlist_head io_hash[RECENT_IO + 1]; 359 struct list_head io_lru; 360 spinlock_t io_lock; 361 362 struct cache_accounting accounting; 363 364 /* The rest of this all shows up in sysfs */ 365 unsigned sequential_cutoff; 366 unsigned readahead; 367 368 unsigned verify:1; 369 unsigned bypass_torture_test:1; 370 371 unsigned partial_stripes_expensive:1; 372 unsigned writeback_metadata:1; 373 unsigned writeback_running:1; 374 unsigned char writeback_percent; 375 unsigned writeback_delay; 376 377 uint64_t writeback_rate_target; 378 int64_t writeback_rate_proportional; 379 int64_t writeback_rate_derivative; 380 int64_t writeback_rate_change; 381 382 unsigned writeback_rate_update_seconds; 383 unsigned writeback_rate_d_term; 384 unsigned writeback_rate_p_term_inverse; 385}; 386 387enum alloc_reserve { 388 RESERVE_BTREE, 389 RESERVE_PRIO, 390 RESERVE_MOVINGGC, 391 RESERVE_NONE, 392 RESERVE_NR, 393}; 394 395struct cache { 396 struct cache_set *set; 397 struct cache_sb sb; 398 struct bio sb_bio; 399 struct bio_vec sb_bv[1]; 400 401 struct kobject kobj; 402 struct block_device *bdev; 403 404 struct task_struct *alloc_thread; 405 406 struct closure prio; 407 struct prio_set *disk_buckets; 408 409 /* 410 * When allocating new buckets, prio_write() gets first dibs - since we 411 * may not be allocate at all without writing priorities and gens. 412 * prio_buckets[] contains the last buckets we wrote priorities to (so 413 * gc can mark them as metadata), prio_next[] contains the buckets 414 * allocated for the next prio write. 415 */ 416 uint64_t *prio_buckets; 417 uint64_t *prio_last_buckets; 418 419 /* 420 * free: Buckets that are ready to be used 421 * 422 * free_inc: Incoming buckets - these are buckets that currently have 423 * cached data in them, and we can't reuse them until after we write 424 * their new gen to disk. After prio_write() finishes writing the new 425 * gens/prios, they'll be moved to the free list (and possibly discarded 426 * in the process) 427 */ 428 DECLARE_FIFO(long, free)[RESERVE_NR]; 429 DECLARE_FIFO(long, free_inc); 430 431 size_t fifo_last_bucket; 432 433 /* Allocation stuff: */ 434 struct bucket *buckets; 435 436 DECLARE_HEAP(struct bucket *, heap); 437 438 /* 439 * If nonzero, we know we aren't going to find any buckets to invalidate 440 * until a gc finishes - otherwise we could pointlessly burn a ton of 441 * cpu 442 */ 443 unsigned invalidate_needs_gc:1; 444 445 bool discard; /* Get rid of? */ 446 447 struct journal_device journal; 448 449 /* The rest of this all shows up in sysfs */ 450#define IO_ERROR_SHIFT 20 451 atomic_t io_errors; 452 atomic_t io_count; 453 454 atomic_long_t meta_sectors_written; 455 atomic_long_t btree_sectors_written; 456 atomic_long_t sectors_written; 457 458 struct bio_split_pool bio_split_hook; 459}; 460 461struct gc_stat { 462 size_t nodes; 463 size_t key_bytes; 464 465 size_t nkeys; 466 uint64_t data; /* sectors */ 467 unsigned in_use; /* percent */ 468}; 469 470/* 471 * Flag bits, for how the cache set is shutting down, and what phase it's at: 472 * 473 * CACHE_SET_UNREGISTERING means we're not just shutting down, we're detaching 474 * all the backing devices first (their cached data gets invalidated, and they 475 * won't automatically reattach). 476 * 477 * CACHE_SET_STOPPING always gets set first when we're closing down a cache set; 478 * we'll continue to run normally for awhile with CACHE_SET_STOPPING set (i.e. 479 * flushing dirty data). 480 * 481 * CACHE_SET_RUNNING means all cache devices have been registered and journal 482 * replay is complete. 483 */ 484#define CACHE_SET_UNREGISTERING 0 485#define CACHE_SET_STOPPING 1 486#define CACHE_SET_RUNNING 2 487 488struct cache_set { 489 struct closure cl; 490 491 struct list_head list; 492 struct kobject kobj; 493 struct kobject internal; 494 struct dentry *debug; 495 struct cache_accounting accounting; 496 497 unsigned long flags; 498 499 struct cache_sb sb; 500 501 struct cache *cache[MAX_CACHES_PER_SET]; 502 struct cache *cache_by_alloc[MAX_CACHES_PER_SET]; 503 int caches_loaded; 504 505 struct bcache_device **devices; 506 struct list_head cached_devs; 507 uint64_t cached_dev_sectors; 508 struct closure caching; 509 510 struct closure sb_write; 511 struct semaphore sb_write_mutex; 512 513 mempool_t *search; 514 mempool_t *bio_meta; 515 struct bio_set *bio_split; 516 517 /* For the btree cache */ 518 struct shrinker shrink; 519 520 /* For the btree cache and anything allocation related */ 521 struct mutex bucket_lock; 522 523 /* log2(bucket_size), in sectors */ 524 unsigned short bucket_bits; 525 526 /* log2(block_size), in sectors */ 527 unsigned short block_bits; 528 529 /* 530 * Default number of pages for a new btree node - may be less than a 531 * full bucket 532 */ 533 unsigned btree_pages; 534 535 /* 536 * Lists of struct btrees; lru is the list for structs that have memory 537 * allocated for actual btree node, freed is for structs that do not. 538 * 539 * We never free a struct btree, except on shutdown - we just put it on 540 * the btree_cache_freed list and reuse it later. This simplifies the 541 * code, and it doesn't cost us much memory as the memory usage is 542 * dominated by buffers that hold the actual btree node data and those 543 * can be freed - and the number of struct btrees allocated is 544 * effectively bounded. 545 * 546 * btree_cache_freeable effectively is a small cache - we use it because 547 * high order page allocations can be rather expensive, and it's quite 548 * common to delete and allocate btree nodes in quick succession. It 549 * should never grow past ~2-3 nodes in practice. 550 */ 551 struct list_head btree_cache; 552 struct list_head btree_cache_freeable; 553 struct list_head btree_cache_freed; 554 555 /* Number of elements in btree_cache + btree_cache_freeable lists */ 556 unsigned btree_cache_used; 557 558 /* 559 * If we need to allocate memory for a new btree node and that 560 * allocation fails, we can cannibalize another node in the btree cache 561 * to satisfy the allocation - lock to guarantee only one thread does 562 * this at a time: 563 */ 564 wait_queue_head_t btree_cache_wait; 565 struct task_struct *btree_cache_alloc_lock; 566 567 /* 568 * When we free a btree node, we increment the gen of the bucket the 569 * node is in - but we can't rewrite the prios and gens until we 570 * finished whatever it is we were doing, otherwise after a crash the 571 * btree node would be freed but for say a split, we might not have the 572 * pointers to the new nodes inserted into the btree yet. 573 * 574 * This is a refcount that blocks prio_write() until the new keys are 575 * written. 576 */ 577 atomic_t prio_blocked; 578 wait_queue_head_t bucket_wait; 579 580 /* 581 * For any bio we don't skip we subtract the number of sectors from 582 * rescale; when it hits 0 we rescale all the bucket priorities. 583 */ 584 atomic_t rescale; 585 /* 586 * When we invalidate buckets, we use both the priority and the amount 587 * of good data to determine which buckets to reuse first - to weight 588 * those together consistently we keep track of the smallest nonzero 589 * priority of any bucket. 590 */ 591 uint16_t min_prio; 592 593 /* 594 * max(gen - last_gc) for all buckets. When it gets too big we have to gc 595 * to keep gens from wrapping around. 596 */ 597 uint8_t need_gc; 598 struct gc_stat gc_stats; 599 size_t nbuckets; 600 601 struct task_struct *gc_thread; 602 /* Where in the btree gc currently is */ 603 struct bkey gc_done; 604 605 /* 606 * The allocation code needs gc_mark in struct bucket to be correct, but 607 * it's not while a gc is in progress. Protected by bucket_lock. 608 */ 609 int gc_mark_valid; 610 611 /* Counts how many sectors bio_insert has added to the cache */ 612 atomic_t sectors_to_gc; 613 614 wait_queue_head_t moving_gc_wait; 615 struct keybuf moving_gc_keys; 616 /* Number of moving GC bios in flight */ 617 struct semaphore moving_in_flight; 618 619 struct workqueue_struct *moving_gc_wq; 620 621 struct btree *root; 622 623#ifdef CONFIG_BCACHE_DEBUG 624 struct btree *verify_data; 625 struct bset *verify_ondisk; 626 struct mutex verify_lock; 627#endif 628 629 unsigned nr_uuids; 630 struct uuid_entry *uuids; 631 BKEY_PADDED(uuid_bucket); 632 struct closure uuid_write; 633 struct semaphore uuid_write_mutex; 634 635 /* 636 * A btree node on disk could have too many bsets for an iterator to fit 637 * on the stack - have to dynamically allocate them 638 */ 639 mempool_t *fill_iter; 640 641 struct bset_sort_state sort; 642 643 /* List of buckets we're currently writing data to */ 644 struct list_head data_buckets; 645 spinlock_t data_bucket_lock; 646 647 struct journal journal; 648 649#define CONGESTED_MAX 1024 650 unsigned congested_last_us; 651 atomic_t congested; 652 653 /* The rest of this all shows up in sysfs */ 654 unsigned congested_read_threshold_us; 655 unsigned congested_write_threshold_us; 656 657 struct time_stats btree_gc_time; 658 struct time_stats btree_split_time; 659 struct time_stats btree_read_time; 660 661 atomic_long_t cache_read_races; 662 atomic_long_t writeback_keys_done; 663 atomic_long_t writeback_keys_failed; 664 665 enum { 666 ON_ERROR_UNREGISTER, 667 ON_ERROR_PANIC, 668 } on_error; 669 unsigned error_limit; 670 unsigned error_decay; 671 672 unsigned short journal_delay_ms; 673 bool expensive_debug_checks; 674 unsigned verify:1; 675 unsigned key_merging_disabled:1; 676 unsigned gc_always_rewrite:1; 677 unsigned shrinker_disabled:1; 678 unsigned copy_gc_enabled:1; 679 680#define BUCKET_HASH_BITS 12 681 struct hlist_head bucket_hash[1 << BUCKET_HASH_BITS]; 682}; 683 684struct bbio { 685 unsigned submit_time_us; 686 union { 687 struct bkey key; 688 uint64_t _pad[3]; 689 /* 690 * We only need pad = 3 here because we only ever carry around a 691 * single pointer - i.e. the pointer we're doing io to/from. 692 */ 693 }; 694 struct bio bio; 695}; 696 697#define BTREE_PRIO USHRT_MAX 698#define INITIAL_PRIO 32768U 699 700#define btree_bytes(c) ((c)->btree_pages * PAGE_SIZE) 701#define btree_blocks(b) \ 702 ((unsigned) (KEY_SIZE(&b->key) >> (b)->c->block_bits)) 703 704#define btree_default_blocks(c) \ 705 ((unsigned) ((PAGE_SECTORS * (c)->btree_pages) >> (c)->block_bits)) 706 707#define bucket_pages(c) ((c)->sb.bucket_size / PAGE_SECTORS) 708#define bucket_bytes(c) ((c)->sb.bucket_size << 9) 709#define block_bytes(c) ((c)->sb.block_size << 9) 710 711#define prios_per_bucket(c) \ 712 ((bucket_bytes(c) - sizeof(struct prio_set)) / \ 713 sizeof(struct bucket_disk)) 714#define prio_buckets(c) \ 715 DIV_ROUND_UP((size_t) (c)->sb.nbuckets, prios_per_bucket(c)) 716 717static inline size_t sector_to_bucket(struct cache_set *c, sector_t s) 718{ 719 return s >> c->bucket_bits; 720} 721 722static inline sector_t bucket_to_sector(struct cache_set *c, size_t b) 723{ 724 return ((sector_t) b) << c->bucket_bits; 725} 726 727static inline sector_t bucket_remainder(struct cache_set *c, sector_t s) 728{ 729 return s & (c->sb.bucket_size - 1); 730} 731 732static inline struct cache *PTR_CACHE(struct cache_set *c, 733 const struct bkey *k, 734 unsigned ptr) 735{ 736 return c->cache[PTR_DEV(k, ptr)]; 737} 738 739static inline size_t PTR_BUCKET_NR(struct cache_set *c, 740 const struct bkey *k, 741 unsigned ptr) 742{ 743 return sector_to_bucket(c, PTR_OFFSET(k, ptr)); 744} 745 746static inline struct bucket *PTR_BUCKET(struct cache_set *c, 747 const struct bkey *k, 748 unsigned ptr) 749{ 750 return PTR_CACHE(c, k, ptr)->buckets + PTR_BUCKET_NR(c, k, ptr); 751} 752 753static inline uint8_t gen_after(uint8_t a, uint8_t b) 754{ 755 uint8_t r = a - b; 756 return r > 128U ? 0 : r; 757} 758 759static inline uint8_t ptr_stale(struct cache_set *c, const struct bkey *k, 760 unsigned i) 761{ 762 return gen_after(PTR_BUCKET(c, k, i)->gen, PTR_GEN(k, i)); 763} 764 765static inline bool ptr_available(struct cache_set *c, const struct bkey *k, 766 unsigned i) 767{ 768 return (PTR_DEV(k, i) < MAX_CACHES_PER_SET) && PTR_CACHE(c, k, i); 769} 770 771/* Btree key macros */ 772 773/* 774 * This is used for various on disk data structures - cache_sb, prio_set, bset, 775 * jset: The checksum is _always_ the first 8 bytes of these structs 776 */ 777#define csum_set(i) \ 778 bch_crc64(((void *) (i)) + sizeof(uint64_t), \ 779 ((void *) bset_bkey_last(i)) - \ 780 (((void *) (i)) + sizeof(uint64_t))) 781 782/* Error handling macros */ 783 784#define btree_bug(b, ...) \ 785do { \ 786 if (bch_cache_set_error((b)->c, __VA_ARGS__)) \ 787 dump_stack(); \ 788} while (0) 789 790#define cache_bug(c, ...) \ 791do { \ 792 if (bch_cache_set_error(c, __VA_ARGS__)) \ 793 dump_stack(); \ 794} while (0) 795 796#define btree_bug_on(cond, b, ...) \ 797do { \ 798 if (cond) \ 799 btree_bug(b, __VA_ARGS__); \ 800} while (0) 801 802#define cache_bug_on(cond, c, ...) \ 803do { \ 804 if (cond) \ 805 cache_bug(c, __VA_ARGS__); \ 806} while (0) 807 808#define cache_set_err_on(cond, c, ...) \ 809do { \ 810 if (cond) \ 811 bch_cache_set_error(c, __VA_ARGS__); \ 812} while (0) 813 814/* Looping macros */ 815 816#define for_each_cache(ca, cs, iter) \ 817 for (iter = 0; ca = cs->cache[iter], iter < (cs)->sb.nr_in_set; iter++) 818 819#define for_each_bucket(b, ca) \ 820 for (b = (ca)->buckets + (ca)->sb.first_bucket; \ 821 b < (ca)->buckets + (ca)->sb.nbuckets; b++) 822 823static inline void cached_dev_put(struct cached_dev *dc) 824{ 825 if (atomic_dec_and_test(&dc->count)) 826 schedule_work(&dc->detach); 827} 828 829static inline bool cached_dev_get(struct cached_dev *dc) 830{ 831 if (!atomic_inc_not_zero(&dc->count)) 832 return false; 833 834 /* Paired with the mb in cached_dev_attach */ 835 smp_mb__after_atomic(); 836 return true; 837} 838 839/* 840 * bucket_gc_gen() returns the difference between the bucket's current gen and 841 * the oldest gen of any pointer into that bucket in the btree (last_gc). 842 */ 843 844static inline uint8_t bucket_gc_gen(struct bucket *b) 845{ 846 return b->gen - b->last_gc; 847} 848 849#define BUCKET_GC_GEN_MAX 96U 850 851#define kobj_attribute_write(n, fn) \ 852 static struct kobj_attribute ksysfs_##n = __ATTR(n, S_IWUSR, NULL, fn) 853 854#define kobj_attribute_rw(n, show, store) \ 855 static struct kobj_attribute ksysfs_##n = \ 856 __ATTR(n, S_IWUSR|S_IRUSR, show, store) 857 858static inline void wake_up_allocators(struct cache_set *c) 859{ 860 struct cache *ca; 861 unsigned i; 862 863 for_each_cache(ca, c, i) 864 wake_up_process(ca->alloc_thread); 865} 866 867/* Forward declarations */ 868 869void bch_count_io_errors(struct cache *, int, const char *); 870void bch_bbio_count_io_errors(struct cache_set *, struct bio *, 871 int, const char *); 872void bch_bbio_endio(struct cache_set *, struct bio *, int, const char *); 873void bch_bbio_free(struct bio *, struct cache_set *); 874struct bio *bch_bbio_alloc(struct cache_set *); 875 876void bch_generic_make_request(struct bio *, struct bio_split_pool *); 877void __bch_submit_bbio(struct bio *, struct cache_set *); 878void bch_submit_bbio(struct bio *, struct cache_set *, struct bkey *, unsigned); 879 880uint8_t bch_inc_gen(struct cache *, struct bucket *); 881void bch_rescale_priorities(struct cache_set *, int); 882 883bool bch_can_invalidate_bucket(struct cache *, struct bucket *); 884void __bch_invalidate_one_bucket(struct cache *, struct bucket *); 885 886void __bch_bucket_free(struct cache *, struct bucket *); 887void bch_bucket_free(struct cache_set *, struct bkey *); 888 889long bch_bucket_alloc(struct cache *, unsigned, bool); 890int __bch_bucket_alloc_set(struct cache_set *, unsigned, 891 struct bkey *, int, bool); 892int bch_bucket_alloc_set(struct cache_set *, unsigned, 893 struct bkey *, int, bool); 894bool bch_alloc_sectors(struct cache_set *, struct bkey *, unsigned, 895 unsigned, unsigned, bool); 896 897__printf(2, 3) 898bool bch_cache_set_error(struct cache_set *, const char *, ...); 899 900void bch_prio_write(struct cache *); 901void bch_write_bdev_super(struct cached_dev *, struct closure *); 902 903extern struct workqueue_struct *bcache_wq; 904extern const char * const bch_cache_modes[]; 905extern struct mutex bch_register_lock; 906extern struct list_head bch_cache_sets; 907 908extern struct kobj_type bch_cached_dev_ktype; 909extern struct kobj_type bch_flash_dev_ktype; 910extern struct kobj_type bch_cache_set_ktype; 911extern struct kobj_type bch_cache_set_internal_ktype; 912extern struct kobj_type bch_cache_ktype; 913 914void bch_cached_dev_release(struct kobject *); 915void bch_flash_dev_release(struct kobject *); 916void bch_cache_set_release(struct kobject *); 917void bch_cache_release(struct kobject *); 918 919int bch_uuid_write(struct cache_set *); 920void bcache_write_super(struct cache_set *); 921 922int bch_flash_dev_create(struct cache_set *c, uint64_t size); 923 924int bch_cached_dev_attach(struct cached_dev *, struct cache_set *); 925void bch_cached_dev_detach(struct cached_dev *); 926void bch_cached_dev_run(struct cached_dev *); 927void bcache_device_stop(struct bcache_device *); 928 929void bch_cache_set_unregister(struct cache_set *); 930void bch_cache_set_stop(struct cache_set *); 931 932struct cache_set *bch_cache_set_alloc(struct cache_sb *); 933void bch_btree_cache_free(struct cache_set *); 934int bch_btree_cache_alloc(struct cache_set *); 935void bch_moving_init_cache_set(struct cache_set *); 936int bch_open_buckets_alloc(struct cache_set *); 937void bch_open_buckets_free(struct cache_set *); 938 939int bch_cache_allocator_start(struct cache *ca); 940 941void bch_debug_exit(void); 942int bch_debug_init(struct kobject *); 943void bch_request_exit(void); 944int bch_request_init(void); 945 946#endif /* _BCACHE_H */ 947