1/* SPDX-License-Identifier: GPL-2.0 */ 2#ifndef _BCACHE_H 3#define _BCACHE_H 4 5/* 6 * SOME HIGH LEVEL CODE DOCUMENTATION: 7 * 8 * Bcache mostly works with cache sets, cache devices, and backing devices. 9 * 10 * Support for multiple cache devices hasn't quite been finished off yet, but 11 * it's about 95% plumbed through. A cache set and its cache devices is sort of 12 * like a md raid array and its component devices. Most of the code doesn't care 13 * about individual cache devices, the main abstraction is the cache set. 14 * 15 * Multiple cache devices is intended to give us the ability to mirror dirty 16 * cached data and metadata, without mirroring clean cached data. 17 * 18 * Backing devices are different, in that they have a lifetime independent of a 19 * cache set. When you register a newly formatted backing device it'll come up 20 * in passthrough mode, and then you can attach and detach a backing device from 21 * a cache set at runtime - while it's mounted and in use. Detaching implicitly 22 * invalidates any cached data for that backing device. 23 * 24 * A cache set can have multiple (many) backing devices attached to it. 25 * 26 * There's also flash only volumes - this is the reason for the distinction 27 * between struct cached_dev and struct bcache_device. A flash only volume 28 * works much like a bcache device that has a backing device, except the 29 * "cached" data is always dirty. The end result is that we get thin 30 * provisioning with very little additional code. 31 * 32 * Flash only volumes work but they're not production ready because the moving 33 * garbage collector needs more work. More on that later. 34 * 35 * BUCKETS/ALLOCATION: 36 * 37 * Bcache is primarily designed for caching, which means that in normal 38 * operation all of our available space will be allocated. Thus, we need an 39 * efficient way of deleting things from the cache so we can write new things to 40 * it. 41 * 42 * To do this, we first divide the cache device up into buckets. A bucket is the 43 * unit of allocation; they're typically around 1 mb - anywhere from 128k to 2M+ 44 * works efficiently. 45 * 46 * Each bucket has a 16 bit priority, and an 8 bit generation associated with 47 * it. The gens and priorities for all the buckets are stored contiguously and 48 * packed on disk (in a linked list of buckets - aside from the superblock, all 49 * of bcache's metadata is stored in buckets). 50 * 51 * The priority is used to implement an LRU. We reset a bucket's priority when 52 * we allocate it or on cache it, and every so often we decrement the priority 53 * of each bucket. It could be used to implement something more sophisticated, 54 * if anyone ever gets around to it. 55 * 56 * The generation is used for invalidating buckets. Each pointer also has an 8 57 * bit generation embedded in it; for a pointer to be considered valid, its gen 58 * must match the gen of the bucket it points into. Thus, to reuse a bucket all 59 * we have to do is increment its gen (and write its new gen to disk; we batch 60 * this up). 61 * 62 * Bcache is entirely COW - we never write twice to a bucket, even buckets that 63 * contain metadata (including btree nodes). 64 * 65 * THE BTREE: 66 * 67 * Bcache is in large part design around the btree. 68 * 69 * At a high level, the btree is just an index of key -> ptr tuples. 70 * 71 * Keys represent extents, and thus have a size field. Keys also have a variable 72 * number of pointers attached to them (potentially zero, which is handy for 73 * invalidating the cache). 74 * 75 * The key itself is an inode:offset pair. The inode number corresponds to a 76 * backing device or a flash only volume. The offset is the ending offset of the 77 * extent within the inode - not the starting offset; this makes lookups 78 * slightly more convenient. 79 * 80 * Pointers contain the cache device id, the offset on that device, and an 8 bit 81 * generation number. More on the gen later. 82 * 83 * Index lookups are not fully abstracted - cache lookups in particular are 84 * still somewhat mixed in with the btree code, but things are headed in that 85 * direction. 86 * 87 * Updates are fairly well abstracted, though. There are two different ways of 88 * updating the btree; insert and replace. 89 * 90 * BTREE_INSERT will just take a list of keys and insert them into the btree - 91 * overwriting (possibly only partially) any extents they overlap with. This is 92 * used to update the index after a write. 93 * 94 * BTREE_REPLACE is really cmpxchg(); it inserts a key into the btree iff it is 95 * overwriting a key that matches another given key. This is used for inserting 96 * data into the cache after a cache miss, and for background writeback, and for 97 * the moving garbage collector. 98 * 99 * There is no "delete" operation; deleting things from the index is 100 * accomplished by either by invalidating pointers (by incrementing a bucket's 101 * gen) or by inserting a key with 0 pointers - which will overwrite anything 102 * previously present at that location in the index. 103 * 104 * This means that there are always stale/invalid keys in the btree. They're 105 * filtered out by the code that iterates through a btree node, and removed when 106 * a btree node is rewritten. 107 * 108 * BTREE NODES: 109 * 110 * Our unit of allocation is a bucket, and we we can't arbitrarily allocate and 111 * free smaller than a bucket - so, that's how big our btree nodes are. 112 * 113 * (If buckets are really big we'll only use part of the bucket for a btree node 114 * - no less than 1/4th - but a bucket still contains no more than a single 115 * btree node. I'd actually like to change this, but for now we rely on the 116 * bucket's gen for deleting btree nodes when we rewrite/split a node.) 117 * 118 * Anyways, btree nodes are big - big enough to be inefficient with a textbook 119 * btree implementation. 120 * 121 * The way this is solved is that btree nodes are internally log structured; we 122 * can append new keys to an existing btree node without rewriting it. This 123 * means each set of keys we write is sorted, but the node is not. 124 * 125 * We maintain this log structure in memory - keeping 1Mb of keys sorted would 126 * be expensive, and we have to distinguish between the keys we have written and 127 * the keys we haven't. So to do a lookup in a btree node, we have to search 128 * each sorted set. But we do merge written sets together lazily, so the cost of 129 * these extra searches is quite low (normally most of the keys in a btree node 130 * will be in one big set, and then there'll be one or two sets that are much 131 * smaller). 132 * 133 * This log structure makes bcache's btree more of a hybrid between a 134 * conventional btree and a compacting data structure, with some of the 135 * advantages of both. 136 * 137 * GARBAGE COLLECTION: 138 * 139 * We can't just invalidate any bucket - it might contain dirty data or 140 * metadata. If it once contained dirty data, other writes might overwrite it 141 * later, leaving no valid pointers into that bucket in the index. 142 * 143 * Thus, the primary purpose of garbage collection is to find buckets to reuse. 144 * It also counts how much valid data it each bucket currently contains, so that 145 * allocation can reuse buckets sooner when they've been mostly overwritten. 146 * 147 * It also does some things that are really internal to the btree 148 * implementation. If a btree node contains pointers that are stale by more than 149 * some threshold, it rewrites the btree node to avoid the bucket's generation 150 * wrapping around. It also merges adjacent btree nodes if they're empty enough. 151 * 152 * THE JOURNAL: 153 * 154 * Bcache's journal is not necessary for consistency; we always strictly 155 * order metadata writes so that the btree and everything else is consistent on 156 * disk in the event of an unclean shutdown, and in fact bcache had writeback 157 * caching (with recovery from unclean shutdown) before journalling was 158 * implemented. 159 * 160 * Rather, the journal is purely a performance optimization; we can't complete a 161 * write until we've updated the index on disk, otherwise the cache would be 162 * inconsistent in the event of an unclean shutdown. This means that without the 163 * journal, on random write workloads we constantly have to update all the leaf 164 * nodes in the btree, and those writes will be mostly empty (appending at most 165 * a few keys each) - highly inefficient in terms of amount of metadata writes, 166 * and it puts more strain on the various btree resorting/compacting code. 167 * 168 * The journal is just a log of keys we've inserted; on startup we just reinsert 169 * all the keys in the open journal entries. That means that when we're updating 170 * a node in the btree, we can wait until a 4k block of keys fills up before 171 * writing them out. 172 * 173 * For simplicity, we only journal updates to leaf nodes; updates to parent 174 * nodes are rare enough (since our leaf nodes are huge) that it wasn't worth 175 * the complexity to deal with journalling them (in particular, journal replay) 176 * - updates to non leaf nodes just happen synchronously (see btree_split()). 177 */ 178 179#define pr_fmt(fmt) "bcache: %s() " fmt, __func__ 180 181#include <linux/bcache.h> 182#include <linux/bio.h> 183#include <linux/kobject.h> 184#include <linux/list.h> 185#include <linux/mutex.h> 186#include <linux/rbtree.h> 187#include <linux/rwsem.h> 188#include <linux/refcount.h> 189#include <linux/types.h> 190#include <linux/workqueue.h> 191#include <linux/kthread.h> 192 193#include "bset.h" 194#include "util.h" 195#include "closure.h" 196 197struct bucket { 198 atomic_t pin; 199 uint16_t prio; 200 uint8_t gen; 201 uint8_t last_gc; /* Most out of date gen in the btree */ 202 uint16_t gc_mark; /* Bitfield used by GC. See below for field */ 203}; 204 205/* 206 * I'd use bitfields for these, but I don't trust the compiler not to screw me 207 * as multiple threads touch struct bucket without locking 208 */ 209 210BITMASK(GC_MARK, struct bucket, gc_mark, 0, 2); 211#define GC_MARK_RECLAIMABLE 1 212#define GC_MARK_DIRTY 2 213#define GC_MARK_METADATA 3 214#define GC_SECTORS_USED_SIZE 13 215#define MAX_GC_SECTORS_USED (~(~0ULL << GC_SECTORS_USED_SIZE)) 216BITMASK(GC_SECTORS_USED, struct bucket, gc_mark, 2, GC_SECTORS_USED_SIZE); 217BITMASK(GC_MOVE, struct bucket, gc_mark, 15, 1); 218 219#include "journal.h" 220#include "stats.h" 221struct search; 222struct btree; 223struct keybuf; 224 225struct keybuf_key { 226 struct rb_node node; 227 BKEY_PADDED(key); 228 void *private; 229}; 230 231struct keybuf { 232 struct bkey last_scanned; 233 spinlock_t lock; 234 235 /* 236 * Beginning and end of range in rb tree - so that we can skip taking 237 * lock and checking the rb tree when we need to check for overlapping 238 * keys. 239 */ 240 struct bkey start; 241 struct bkey end; 242 243 struct rb_root keys; 244 245#define KEYBUF_NR 500 246 DECLARE_ARRAY_ALLOCATOR(struct keybuf_key, freelist, KEYBUF_NR); 247}; 248 249struct bcache_device { 250 struct closure cl; 251 252 struct kobject kobj; 253 254 struct cache_set *c; 255 unsigned int id; 256#define BCACHEDEVNAME_SIZE 12 257 char name[BCACHEDEVNAME_SIZE]; 258 259 struct gendisk *disk; 260 261 unsigned long flags; 262#define BCACHE_DEV_CLOSING 0 263#define BCACHE_DEV_DETACHING 1 264#define BCACHE_DEV_UNLINK_DONE 2 265#define BCACHE_DEV_WB_RUNNING 3 266#define BCACHE_DEV_RATE_DW_RUNNING 4 267 int nr_stripes; 268#define BCH_MIN_STRIPE_SZ ((4 << 20) >> SECTOR_SHIFT) 269 unsigned int stripe_size; 270 atomic_t *stripe_sectors_dirty; 271 unsigned long *full_dirty_stripes; 272 273 struct bio_set bio_split; 274 275 unsigned int data_csum:1; 276 277 int (*cache_miss)(struct btree *b, struct search *s, 278 struct bio *bio, unsigned int sectors); 279 int (*ioctl)(struct bcache_device *d, fmode_t mode, 280 unsigned int cmd, unsigned long arg); 281}; 282 283struct io { 284 /* Used to track sequential IO so it can be skipped */ 285 struct hlist_node hash; 286 struct list_head lru; 287 288 unsigned long jiffies; 289 unsigned int sequential; 290 sector_t last; 291}; 292 293enum stop_on_failure { 294 BCH_CACHED_DEV_STOP_AUTO = 0, 295 BCH_CACHED_DEV_STOP_ALWAYS, 296 BCH_CACHED_DEV_STOP_MODE_MAX, 297}; 298 299struct cached_dev { 300 struct list_head list; 301 struct bcache_device disk; 302 struct block_device *bdev; 303 304 struct cache_sb sb; 305 struct cache_sb_disk *sb_disk; 306 struct bio sb_bio; 307 struct bio_vec sb_bv[1]; 308 struct closure sb_write; 309 struct semaphore sb_write_mutex; 310 311 /* Refcount on the cache set. Always nonzero when we're caching. */ 312 refcount_t count; 313 struct work_struct detach; 314 315 /* 316 * Device might not be running if it's dirty and the cache set hasn't 317 * showed up yet. 318 */ 319 atomic_t running; 320 321 /* 322 * Writes take a shared lock from start to finish; scanning for dirty 323 * data to refill the rb tree requires an exclusive lock. 324 */ 325 struct rw_semaphore writeback_lock; 326 327 /* 328 * Nonzero, and writeback has a refcount (d->count), iff there is dirty 329 * data in the cache. Protected by writeback_lock; must have an 330 * shared lock to set and exclusive lock to clear. 331 */ 332 atomic_t has_dirty; 333 334#define BCH_CACHE_READA_ALL 0 335#define BCH_CACHE_READA_META_ONLY 1 336 unsigned int cache_readahead_policy; 337 struct bch_ratelimit writeback_rate; 338 struct delayed_work writeback_rate_update; 339 340 /* Limit number of writeback bios in flight */ 341 struct semaphore in_flight; 342 struct task_struct *writeback_thread; 343 struct workqueue_struct *writeback_write_wq; 344 345 struct keybuf writeback_keys; 346 347 struct task_struct *status_update_thread; 348 /* 349 * Order the write-half of writeback operations strongly in dispatch 350 * order. (Maintain LBA order; don't allow reads completing out of 351 * order to re-order the writes...) 352 */ 353 struct closure_waitlist writeback_ordering_wait; 354 atomic_t writeback_sequence_next; 355 356 /* For tracking sequential IO */ 357#define RECENT_IO_BITS 7 358#define RECENT_IO (1 << RECENT_IO_BITS) 359 struct io io[RECENT_IO]; 360 struct hlist_head io_hash[RECENT_IO + 1]; 361 struct list_head io_lru; 362 spinlock_t io_lock; 363 364 struct cache_accounting accounting; 365 366 /* The rest of this all shows up in sysfs */ 367 unsigned int sequential_cutoff; 368 unsigned int readahead; 369 370 unsigned int io_disable:1; 371 unsigned int verify:1; 372 unsigned int bypass_torture_test:1; 373 374 unsigned int partial_stripes_expensive:1; 375 unsigned int writeback_metadata:1; 376 unsigned int writeback_running:1; 377 unsigned char writeback_percent; 378 unsigned int writeback_delay; 379 380 uint64_t writeback_rate_target; 381 int64_t writeback_rate_proportional; 382 int64_t writeback_rate_integral; 383 int64_t writeback_rate_integral_scaled; 384 int32_t writeback_rate_change; 385 386 unsigned int writeback_rate_update_seconds; 387 unsigned int writeback_rate_i_term_inverse; 388 unsigned int writeback_rate_p_term_inverse; 389 unsigned int writeback_rate_minimum; 390 391 enum stop_on_failure stop_when_cache_set_failed; 392#define DEFAULT_CACHED_DEV_ERROR_LIMIT 64 393 atomic_t io_errors; 394 unsigned int error_limit; 395 unsigned int offline_seconds; 396 397 char backing_dev_name[BDEVNAME_SIZE]; 398}; 399 400enum alloc_reserve { 401 RESERVE_BTREE, 402 RESERVE_PRIO, 403 RESERVE_MOVINGGC, 404 RESERVE_NONE, 405 RESERVE_NR, 406}; 407 408struct cache { 409 struct cache_set *set; 410 struct cache_sb sb; 411 struct cache_sb_disk *sb_disk; 412 struct bio sb_bio; 413 struct bio_vec sb_bv[1]; 414 415 struct kobject kobj; 416 struct block_device *bdev; 417 418 struct task_struct *alloc_thread; 419 420 struct closure prio; 421 struct prio_set *disk_buckets; 422 423 /* 424 * When allocating new buckets, prio_write() gets first dibs - since we 425 * may not be allocate at all without writing priorities and gens. 426 * prio_last_buckets[] contains the last buckets we wrote priorities to 427 * (so gc can mark them as metadata), prio_buckets[] contains the 428 * buckets allocated for the next prio write. 429 */ 430 uint64_t *prio_buckets; 431 uint64_t *prio_last_buckets; 432 433 /* 434 * free: Buckets that are ready to be used 435 * 436 * free_inc: Incoming buckets - these are buckets that currently have 437 * cached data in them, and we can't reuse them until after we write 438 * their new gen to disk. After prio_write() finishes writing the new 439 * gens/prios, they'll be moved to the free list (and possibly discarded 440 * in the process) 441 */ 442 DECLARE_FIFO(long, free)[RESERVE_NR]; 443 DECLARE_FIFO(long, free_inc); 444 445 size_t fifo_last_bucket; 446 447 /* Allocation stuff: */ 448 struct bucket *buckets; 449 450 DECLARE_HEAP(struct bucket *, heap); 451 452 /* 453 * If nonzero, we know we aren't going to find any buckets to invalidate 454 * until a gc finishes - otherwise we could pointlessly burn a ton of 455 * cpu 456 */ 457 unsigned int invalidate_needs_gc; 458 459 bool discard; /* Get rid of? */ 460 461 struct journal_device journal; 462 463 /* The rest of this all shows up in sysfs */ 464#define IO_ERROR_SHIFT 20 465 atomic_t io_errors; 466 atomic_t io_count; 467 468 atomic_long_t meta_sectors_written; 469 atomic_long_t btree_sectors_written; 470 atomic_long_t sectors_written; 471 472 char cache_dev_name[BDEVNAME_SIZE]; 473}; 474 475struct gc_stat { 476 size_t nodes; 477 size_t nodes_pre; 478 size_t key_bytes; 479 480 size_t nkeys; 481 uint64_t data; /* sectors */ 482 unsigned int in_use; /* percent */ 483}; 484 485/* 486 * Flag bits, for how the cache set is shutting down, and what phase it's at: 487 * 488 * CACHE_SET_UNREGISTERING means we're not just shutting down, we're detaching 489 * all the backing devices first (their cached data gets invalidated, and they 490 * won't automatically reattach). 491 * 492 * CACHE_SET_STOPPING always gets set first when we're closing down a cache set; 493 * we'll continue to run normally for awhile with CACHE_SET_STOPPING set (i.e. 494 * flushing dirty data). 495 * 496 * CACHE_SET_RUNNING means all cache devices have been registered and journal 497 * replay is complete. 498 * 499 * CACHE_SET_IO_DISABLE is set when bcache is stopping the whold cache set, all 500 * external and internal I/O should be denied when this flag is set. 501 * 502 */ 503#define CACHE_SET_UNREGISTERING 0 504#define CACHE_SET_STOPPING 1 505#define CACHE_SET_RUNNING 2 506#define CACHE_SET_IO_DISABLE 3 507 508struct cache_set { 509 struct closure cl; 510 511 struct list_head list; 512 struct kobject kobj; 513 struct kobject internal; 514 struct dentry *debug; 515 struct cache_accounting accounting; 516 517 unsigned long flags; 518 atomic_t idle_counter; 519 atomic_t at_max_writeback_rate; 520 521 struct cache *cache; 522 523 struct bcache_device **devices; 524 unsigned int devices_max_used; 525 atomic_t attached_dev_nr; 526 struct list_head cached_devs; 527 uint64_t cached_dev_sectors; 528 atomic_long_t flash_dev_dirty_sectors; 529 struct closure caching; 530 531 struct closure sb_write; 532 struct semaphore sb_write_mutex; 533 534 mempool_t search; 535 mempool_t bio_meta; 536 struct bio_set bio_split; 537 538 /* For the btree cache */ 539 struct shrinker shrink; 540 541 /* For the btree cache and anything allocation related */ 542 struct mutex bucket_lock; 543 544 /* log2(bucket_size), in sectors */ 545 unsigned short bucket_bits; 546 547 /* log2(block_size), in sectors */ 548 unsigned short block_bits; 549 550 /* 551 * Default number of pages for a new btree node - may be less than a 552 * full bucket 553 */ 554 unsigned int btree_pages; 555 556 /* 557 * Lists of struct btrees; lru is the list for structs that have memory 558 * allocated for actual btree node, freed is for structs that do not. 559 * 560 * We never free a struct btree, except on shutdown - we just put it on 561 * the btree_cache_freed list and reuse it later. This simplifies the 562 * code, and it doesn't cost us much memory as the memory usage is 563 * dominated by buffers that hold the actual btree node data and those 564 * can be freed - and the number of struct btrees allocated is 565 * effectively bounded. 566 * 567 * btree_cache_freeable effectively is a small cache - we use it because 568 * high order page allocations can be rather expensive, and it's quite 569 * common to delete and allocate btree nodes in quick succession. It 570 * should never grow past ~2-3 nodes in practice. 571 */ 572 struct list_head btree_cache; 573 struct list_head btree_cache_freeable; 574 struct list_head btree_cache_freed; 575 576 /* Number of elements in btree_cache + btree_cache_freeable lists */ 577 unsigned int btree_cache_used; 578 579 /* 580 * If we need to allocate memory for a new btree node and that 581 * allocation fails, we can cannibalize another node in the btree cache 582 * to satisfy the allocation - lock to guarantee only one thread does 583 * this at a time: 584 */ 585 wait_queue_head_t btree_cache_wait; 586 struct task_struct *btree_cache_alloc_lock; 587 spinlock_t btree_cannibalize_lock; 588 589 /* 590 * When we free a btree node, we increment the gen of the bucket the 591 * node is in - but we can't rewrite the prios and gens until we 592 * finished whatever it is we were doing, otherwise after a crash the 593 * btree node would be freed but for say a split, we might not have the 594 * pointers to the new nodes inserted into the btree yet. 595 * 596 * This is a refcount that blocks prio_write() until the new keys are 597 * written. 598 */ 599 atomic_t prio_blocked; 600 wait_queue_head_t bucket_wait; 601 602 /* 603 * For any bio we don't skip we subtract the number of sectors from 604 * rescale; when it hits 0 we rescale all the bucket priorities. 605 */ 606 atomic_t rescale; 607 /* 608 * used for GC, identify if any front side I/Os is inflight 609 */ 610 atomic_t search_inflight; 611 /* 612 * When we invalidate buckets, we use both the priority and the amount 613 * of good data to determine which buckets to reuse first - to weight 614 * those together consistently we keep track of the smallest nonzero 615 * priority of any bucket. 616 */ 617 uint16_t min_prio; 618 619 /* 620 * max(gen - last_gc) for all buckets. When it gets too big we have to 621 * gc to keep gens from wrapping around. 622 */ 623 uint8_t need_gc; 624 struct gc_stat gc_stats; 625 size_t nbuckets; 626 size_t avail_nbuckets; 627 628 struct task_struct *gc_thread; 629 /* Where in the btree gc currently is */ 630 struct bkey gc_done; 631 632 /* 633 * For automatical garbage collection after writeback completed, this 634 * varialbe is used as bit fields, 635 * - 0000 0001b (BCH_ENABLE_AUTO_GC): enable gc after writeback 636 * - 0000 0010b (BCH_DO_AUTO_GC): do gc after writeback 637 * This is an optimization for following write request after writeback 638 * finished, but read hit rate dropped due to clean data on cache is 639 * discarded. Unless user explicitly sets it via sysfs, it won't be 640 * enabled. 641 */ 642#define BCH_ENABLE_AUTO_GC 1 643#define BCH_DO_AUTO_GC 2 644 uint8_t gc_after_writeback; 645 646 /* 647 * The allocation code needs gc_mark in struct bucket to be correct, but 648 * it's not while a gc is in progress. Protected by bucket_lock. 649 */ 650 int gc_mark_valid; 651 652 /* Counts how many sectors bio_insert has added to the cache */ 653 atomic_t sectors_to_gc; 654 wait_queue_head_t gc_wait; 655 656 struct keybuf moving_gc_keys; 657 /* Number of moving GC bios in flight */ 658 struct semaphore moving_in_flight; 659 660 struct workqueue_struct *moving_gc_wq; 661 662 struct btree *root; 663 664#ifdef CONFIG_BCACHE_DEBUG 665 struct btree *verify_data; 666 struct bset *verify_ondisk; 667 struct mutex verify_lock; 668#endif 669 670 uint8_t set_uuid[16]; 671 unsigned int nr_uuids; 672 struct uuid_entry *uuids; 673 BKEY_PADDED(uuid_bucket); 674 struct closure uuid_write; 675 struct semaphore uuid_write_mutex; 676 677 /* 678 * A btree node on disk could have too many bsets for an iterator to fit 679 * on the stack - have to dynamically allocate them. 680 * bch_cache_set_alloc() will make sure the pool can allocate iterators 681 * equipped with enough room that can host 682 * (sb.bucket_size / sb.block_size) 683 * btree_iter_sets, which is more than static MAX_BSETS. 684 */ 685 mempool_t fill_iter; 686 687 struct bset_sort_state sort; 688 689 /* List of buckets we're currently writing data to */ 690 struct list_head data_buckets; 691 spinlock_t data_bucket_lock; 692 693 struct journal journal; 694 695#define CONGESTED_MAX 1024 696 unsigned int congested_last_us; 697 atomic_t congested; 698 699 /* The rest of this all shows up in sysfs */ 700 unsigned int congested_read_threshold_us; 701 unsigned int congested_write_threshold_us; 702 703 struct time_stats btree_gc_time; 704 struct time_stats btree_split_time; 705 struct time_stats btree_read_time; 706 707 atomic_long_t cache_read_races; 708 atomic_long_t writeback_keys_done; 709 atomic_long_t writeback_keys_failed; 710 711 atomic_long_t reclaim; 712 atomic_long_t reclaimed_journal_buckets; 713 atomic_long_t flush_write; 714 715 enum { 716 ON_ERROR_UNREGISTER, 717 ON_ERROR_PANIC, 718 } on_error; 719#define DEFAULT_IO_ERROR_LIMIT 8 720 unsigned int error_limit; 721 unsigned int error_decay; 722 723 unsigned short journal_delay_ms; 724 bool expensive_debug_checks; 725 unsigned int verify:1; 726 unsigned int key_merging_disabled:1; 727 unsigned int gc_always_rewrite:1; 728 unsigned int shrinker_disabled:1; 729 unsigned int copy_gc_enabled:1; 730 unsigned int idle_max_writeback_rate_enabled:1; 731 732#define BUCKET_HASH_BITS 12 733 struct hlist_head bucket_hash[1 << BUCKET_HASH_BITS]; 734}; 735 736struct bbio { 737 unsigned int submit_time_us; 738 union { 739 struct bkey key; 740 uint64_t _pad[3]; 741 /* 742 * We only need pad = 3 here because we only ever carry around a 743 * single pointer - i.e. the pointer we're doing io to/from. 744 */ 745 }; 746 struct bio bio; 747}; 748 749#define BTREE_PRIO USHRT_MAX 750#define INITIAL_PRIO 32768U 751 752#define btree_bytes(c) ((c)->btree_pages * PAGE_SIZE) 753#define btree_blocks(b) \ 754 ((unsigned int) (KEY_SIZE(&b->key) >> (b)->c->block_bits)) 755 756#define btree_default_blocks(c) \ 757 ((unsigned int) ((PAGE_SECTORS * (c)->btree_pages) >> (c)->block_bits)) 758 759#define bucket_bytes(ca) ((ca)->sb.bucket_size << 9) 760#define block_bytes(ca) ((ca)->sb.block_size << 9) 761 762static inline unsigned int meta_bucket_pages(struct cache_sb *sb) 763{ 764 unsigned int n, max_pages; 765 766 max_pages = min_t(unsigned int, 767 __rounddown_pow_of_two(USHRT_MAX) / PAGE_SECTORS, 768 MAX_ORDER_NR_PAGES); 769 770 n = sb->bucket_size / PAGE_SECTORS; 771 if (n > max_pages) 772 n = max_pages; 773 774 return n; 775} 776 777static inline unsigned int meta_bucket_bytes(struct cache_sb *sb) 778{ 779 return meta_bucket_pages(sb) << PAGE_SHIFT; 780} 781 782#define prios_per_bucket(ca) \ 783 ((meta_bucket_bytes(&(ca)->sb) - sizeof(struct prio_set)) / \ 784 sizeof(struct bucket_disk)) 785 786#define prio_buckets(ca) \ 787 DIV_ROUND_UP((size_t) (ca)->sb.nbuckets, prios_per_bucket(ca)) 788 789static inline size_t sector_to_bucket(struct cache_set *c, sector_t s) 790{ 791 return s >> c->bucket_bits; 792} 793 794static inline sector_t bucket_to_sector(struct cache_set *c, size_t b) 795{ 796 return ((sector_t) b) << c->bucket_bits; 797} 798 799static inline sector_t bucket_remainder(struct cache_set *c, sector_t s) 800{ 801 return s & (c->cache->sb.bucket_size - 1); 802} 803 804static inline struct cache *PTR_CACHE(struct cache_set *c, 805 const struct bkey *k, 806 unsigned int ptr) 807{ 808 return c->cache; 809} 810 811static inline size_t PTR_BUCKET_NR(struct cache_set *c, 812 const struct bkey *k, 813 unsigned int ptr) 814{ 815 return sector_to_bucket(c, PTR_OFFSET(k, ptr)); 816} 817 818static inline struct bucket *PTR_BUCKET(struct cache_set *c, 819 const struct bkey *k, 820 unsigned int ptr) 821{ 822 return PTR_CACHE(c, k, ptr)->buckets + PTR_BUCKET_NR(c, k, ptr); 823} 824 825static inline uint8_t gen_after(uint8_t a, uint8_t b) 826{ 827 uint8_t r = a - b; 828 829 return r > 128U ? 0 : r; 830} 831 832static inline uint8_t ptr_stale(struct cache_set *c, const struct bkey *k, 833 unsigned int i) 834{ 835 return gen_after(PTR_BUCKET(c, k, i)->gen, PTR_GEN(k, i)); 836} 837 838static inline bool ptr_available(struct cache_set *c, const struct bkey *k, 839 unsigned int i) 840{ 841 return (PTR_DEV(k, i) < MAX_CACHES_PER_SET) && PTR_CACHE(c, k, i); 842} 843 844/* Btree key macros */ 845 846/* 847 * This is used for various on disk data structures - cache_sb, prio_set, bset, 848 * jset: The checksum is _always_ the first 8 bytes of these structs 849 */ 850#define csum_set(i) \ 851 bch_crc64(((void *) (i)) + sizeof(uint64_t), \ 852 ((void *) bset_bkey_last(i)) - \ 853 (((void *) (i)) + sizeof(uint64_t))) 854 855/* Error handling macros */ 856 857#define btree_bug(b, ...) \ 858do { \ 859 if (bch_cache_set_error((b)->c, __VA_ARGS__)) \ 860 dump_stack(); \ 861} while (0) 862 863#define cache_bug(c, ...) \ 864do { \ 865 if (bch_cache_set_error(c, __VA_ARGS__)) \ 866 dump_stack(); \ 867} while (0) 868 869#define btree_bug_on(cond, b, ...) \ 870do { \ 871 if (cond) \ 872 btree_bug(b, __VA_ARGS__); \ 873} while (0) 874 875#define cache_bug_on(cond, c, ...) \ 876do { \ 877 if (cond) \ 878 cache_bug(c, __VA_ARGS__); \ 879} while (0) 880 881#define cache_set_err_on(cond, c, ...) \ 882do { \ 883 if (cond) \ 884 bch_cache_set_error(c, __VA_ARGS__); \ 885} while (0) 886 887/* Looping macros */ 888 889#define for_each_bucket(b, ca) \ 890 for (b = (ca)->buckets + (ca)->sb.first_bucket; \ 891 b < (ca)->buckets + (ca)->sb.nbuckets; b++) 892 893static inline void cached_dev_put(struct cached_dev *dc) 894{ 895 if (refcount_dec_and_test(&dc->count)) 896 schedule_work(&dc->detach); 897} 898 899static inline bool cached_dev_get(struct cached_dev *dc) 900{ 901 if (!refcount_inc_not_zero(&dc->count)) 902 return false; 903 904 /* Paired with the mb in cached_dev_attach */ 905 smp_mb__after_atomic(); 906 return true; 907} 908 909/* 910 * bucket_gc_gen() returns the difference between the bucket's current gen and 911 * the oldest gen of any pointer into that bucket in the btree (last_gc). 912 */ 913 914static inline uint8_t bucket_gc_gen(struct bucket *b) 915{ 916 return b->gen - b->last_gc; 917} 918 919#define BUCKET_GC_GEN_MAX 96U 920 921#define kobj_attribute_write(n, fn) \ 922 static struct kobj_attribute ksysfs_##n = __ATTR(n, 0200, NULL, fn) 923 924#define kobj_attribute_rw(n, show, store) \ 925 static struct kobj_attribute ksysfs_##n = \ 926 __ATTR(n, 0600, show, store) 927 928static inline void wake_up_allocators(struct cache_set *c) 929{ 930 struct cache *ca = c->cache; 931 932 wake_up_process(ca->alloc_thread); 933} 934 935static inline void closure_bio_submit(struct cache_set *c, 936 struct bio *bio, 937 struct closure *cl) 938{ 939 closure_get(cl); 940 if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &c->flags))) { 941 bio->bi_status = BLK_STS_IOERR; 942 bio_endio(bio); 943 return; 944 } 945 submit_bio_noacct(bio); 946} 947 948/* 949 * Prevent the kthread exits directly, and make sure when kthread_stop() 950 * is called to stop a kthread, it is still alive. If a kthread might be 951 * stopped by CACHE_SET_IO_DISABLE bit set, wait_for_kthread_stop() is 952 * necessary before the kthread returns. 953 */ 954static inline void wait_for_kthread_stop(void) 955{ 956 while (!kthread_should_stop()) { 957 set_current_state(TASK_INTERRUPTIBLE); 958 schedule(); 959 } 960} 961 962/* Forward declarations */ 963 964void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio); 965void bch_count_io_errors(struct cache *ca, blk_status_t error, 966 int is_read, const char *m); 967void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio, 968 blk_status_t error, const char *m); 969void bch_bbio_endio(struct cache_set *c, struct bio *bio, 970 blk_status_t error, const char *m); 971void bch_bbio_free(struct bio *bio, struct cache_set *c); 972struct bio *bch_bbio_alloc(struct cache_set *c); 973 974void __bch_submit_bbio(struct bio *bio, struct cache_set *c); 975void bch_submit_bbio(struct bio *bio, struct cache_set *c, 976 struct bkey *k, unsigned int ptr); 977 978uint8_t bch_inc_gen(struct cache *ca, struct bucket *b); 979void bch_rescale_priorities(struct cache_set *c, int sectors); 980 981bool bch_can_invalidate_bucket(struct cache *ca, struct bucket *b); 982void __bch_invalidate_one_bucket(struct cache *ca, struct bucket *b); 983 984void __bch_bucket_free(struct cache *ca, struct bucket *b); 985void bch_bucket_free(struct cache_set *c, struct bkey *k); 986 987long bch_bucket_alloc(struct cache *ca, unsigned int reserve, bool wait); 988int __bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve, 989 struct bkey *k, bool wait); 990int bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve, 991 struct bkey *k, bool wait); 992bool bch_alloc_sectors(struct cache_set *c, struct bkey *k, 993 unsigned int sectors, unsigned int write_point, 994 unsigned int write_prio, bool wait); 995bool bch_cached_dev_error(struct cached_dev *dc); 996 997__printf(2, 3) 998bool bch_cache_set_error(struct cache_set *c, const char *fmt, ...); 999 1000int bch_prio_write(struct cache *ca, bool wait); 1001void bch_write_bdev_super(struct cached_dev *dc, struct closure *parent); 1002 1003extern struct workqueue_struct *bcache_wq; 1004extern struct workqueue_struct *bch_journal_wq; 1005extern struct workqueue_struct *bch_flush_wq; 1006extern struct mutex bch_register_lock; 1007extern struct list_head bch_cache_sets; 1008 1009extern struct kobj_type bch_cached_dev_ktype; 1010extern struct kobj_type bch_flash_dev_ktype; 1011extern struct kobj_type bch_cache_set_ktype; 1012extern struct kobj_type bch_cache_set_internal_ktype; 1013extern struct kobj_type bch_cache_ktype; 1014 1015void bch_cached_dev_release(struct kobject *kobj); 1016void bch_flash_dev_release(struct kobject *kobj); 1017void bch_cache_set_release(struct kobject *kobj); 1018void bch_cache_release(struct kobject *kobj); 1019 1020int bch_uuid_write(struct cache_set *c); 1021void bcache_write_super(struct cache_set *c); 1022 1023int bch_flash_dev_create(struct cache_set *c, uint64_t size); 1024 1025int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c, 1026 uint8_t *set_uuid); 1027void bch_cached_dev_detach(struct cached_dev *dc); 1028int bch_cached_dev_run(struct cached_dev *dc); 1029void bcache_device_stop(struct bcache_device *d); 1030 1031void bch_cache_set_unregister(struct cache_set *c); 1032void bch_cache_set_stop(struct cache_set *c); 1033 1034struct cache_set *bch_cache_set_alloc(struct cache_sb *sb); 1035void bch_btree_cache_free(struct cache_set *c); 1036int bch_btree_cache_alloc(struct cache_set *c); 1037void bch_moving_init_cache_set(struct cache_set *c); 1038int bch_open_buckets_alloc(struct cache_set *c); 1039void bch_open_buckets_free(struct cache_set *c); 1040 1041int bch_cache_allocator_start(struct cache *ca); 1042 1043void bch_debug_exit(void); 1044void bch_debug_init(void); 1045void bch_request_exit(void); 1046int bch_request_init(void); 1047void bch_btree_exit(void); 1048int bch_btree_init(void); 1049 1050#endif /* _BCACHE_H */ 1051