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 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/bio.h> 182#include <linux/closure.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 "bcache_ondisk.h" 194#include "bset.h" 195#include "util.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, blk_mode_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 struct file *bdev_file; 304 305 struct cache_sb sb; 306 struct cache_sb_disk *sb_disk; 307 struct bio sb_bio; 308 struct bio_vec sb_bv[1]; 309 struct closure sb_write; 310 struct semaphore sb_write_mutex; 311 312 /* Refcount on the cache set. Always nonzero when we're caching. */ 313 refcount_t count; 314 struct work_struct detach; 315 316 /* 317 * Device might not be running if it's dirty and the cache set hasn't 318 * showed up yet. 319 */ 320 atomic_t running; 321 322 /* 323 * Writes take a shared lock from start to finish; scanning for dirty 324 * data to refill the rb tree requires an exclusive lock. 325 */ 326 struct rw_semaphore writeback_lock; 327 328 /* 329 * Nonzero, and writeback has a refcount (d->count), iff there is dirty 330 * data in the cache. Protected by writeback_lock; must have an 331 * shared lock to set and exclusive lock to clear. 332 */ 333 atomic_t has_dirty; 334 335#define BCH_CACHE_READA_ALL 0 336#define BCH_CACHE_READA_META_ONLY 1 337 unsigned int cache_readahead_policy; 338 struct bch_ratelimit writeback_rate; 339 struct delayed_work writeback_rate_update; 340 341 /* Limit number of writeback bios in flight */ 342 struct semaphore in_flight; 343 struct task_struct *writeback_thread; 344 struct workqueue_struct *writeback_write_wq; 345 346 struct keybuf writeback_keys; 347 348 struct task_struct *status_update_thread; 349 /* 350 * Order the write-half of writeback operations strongly in dispatch 351 * order. (Maintain LBA order; don't allow reads completing out of 352 * order to re-order the writes...) 353 */ 354 struct closure_waitlist writeback_ordering_wait; 355 atomic_t writeback_sequence_next; 356 357 /* For tracking sequential IO */ 358#define RECENT_IO_BITS 7 359#define RECENT_IO (1 << RECENT_IO_BITS) 360 struct io io[RECENT_IO]; 361 struct hlist_head io_hash[RECENT_IO + 1]; 362 struct list_head io_lru; 363 spinlock_t io_lock; 364 365 struct cache_accounting accounting; 366 367 /* The rest of this all shows up in sysfs */ 368 unsigned int sequential_cutoff; 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 int writeback_consider_fragment:1; 378 unsigned char writeback_percent; 379 unsigned int writeback_delay; 380 381 uint64_t writeback_rate_target; 382 int64_t writeback_rate_proportional; 383 int64_t writeback_rate_integral; 384 int64_t writeback_rate_integral_scaled; 385 int32_t writeback_rate_change; 386 387 unsigned int writeback_rate_update_seconds; 388 unsigned int writeback_rate_i_term_inverse; 389 unsigned int writeback_rate_p_term_inverse; 390 unsigned int writeback_rate_fp_term_low; 391 unsigned int writeback_rate_fp_term_mid; 392 unsigned int writeback_rate_fp_term_high; 393 unsigned int writeback_rate_minimum; 394 395 enum stop_on_failure stop_when_cache_set_failed; 396#define DEFAULT_CACHED_DEV_ERROR_LIMIT 64 397 atomic_t io_errors; 398 unsigned int error_limit; 399 unsigned int offline_seconds; 400 401 /* 402 * Retry to update writeback_rate if contention happens for 403 * down_read(dc->writeback_lock) in update_writeback_rate() 404 */ 405#define BCH_WBRATE_UPDATE_MAX_SKIPS 15 406 unsigned int rate_update_retry; 407}; 408 409enum alloc_reserve { 410 RESERVE_BTREE, 411 RESERVE_PRIO, 412 RESERVE_MOVINGGC, 413 RESERVE_NONE, 414 RESERVE_NR, 415}; 416 417struct cache { 418 struct cache_set *set; 419 struct cache_sb sb; 420 struct cache_sb_disk *sb_disk; 421 struct bio sb_bio; 422 struct bio_vec sb_bv[1]; 423 424 struct kobject kobj; 425 struct block_device *bdev; 426 struct file *bdev_file; 427 428 struct task_struct *alloc_thread; 429 430 struct closure prio; 431 struct prio_set *disk_buckets; 432 433 /* 434 * When allocating new buckets, prio_write() gets first dibs - since we 435 * may not be allocate at all without writing priorities and gens. 436 * prio_last_buckets[] contains the last buckets we wrote priorities to 437 * (so gc can mark them as metadata), prio_buckets[] contains the 438 * buckets allocated for the next prio write. 439 */ 440 uint64_t *prio_buckets; 441 uint64_t *prio_last_buckets; 442 443 /* 444 * free: Buckets that are ready to be used 445 * 446 * free_inc: Incoming buckets - these are buckets that currently have 447 * cached data in them, and we can't reuse them until after we write 448 * their new gen to disk. After prio_write() finishes writing the new 449 * gens/prios, they'll be moved to the free list (and possibly discarded 450 * in the process) 451 */ 452 DECLARE_FIFO(long, free)[RESERVE_NR]; 453 DECLARE_FIFO(long, free_inc); 454 455 size_t fifo_last_bucket; 456 457 /* Allocation stuff: */ 458 struct bucket *buckets; 459 460 DECLARE_HEAP(struct bucket *, heap); 461 462 /* 463 * If nonzero, we know we aren't going to find any buckets to invalidate 464 * until a gc finishes - otherwise we could pointlessly burn a ton of 465 * cpu 466 */ 467 unsigned int invalidate_needs_gc; 468 469 bool discard; /* Get rid of? */ 470 471 struct journal_device journal; 472 473 /* The rest of this all shows up in sysfs */ 474#define IO_ERROR_SHIFT 20 475 atomic_t io_errors; 476 atomic_t io_count; 477 478 atomic_long_t meta_sectors_written; 479 atomic_long_t btree_sectors_written; 480 atomic_long_t sectors_written; 481}; 482 483struct gc_stat { 484 size_t nodes; 485 size_t nodes_pre; 486 size_t key_bytes; 487 488 size_t nkeys; 489 uint64_t data; /* sectors */ 490 unsigned int in_use; /* percent */ 491}; 492 493/* 494 * Flag bits, for how the cache set is shutting down, and what phase it's at: 495 * 496 * CACHE_SET_UNREGISTERING means we're not just shutting down, we're detaching 497 * all the backing devices first (their cached data gets invalidated, and they 498 * won't automatically reattach). 499 * 500 * CACHE_SET_STOPPING always gets set first when we're closing down a cache set; 501 * we'll continue to run normally for awhile with CACHE_SET_STOPPING set (i.e. 502 * flushing dirty data). 503 * 504 * CACHE_SET_RUNNING means all cache devices have been registered and journal 505 * replay is complete. 506 * 507 * CACHE_SET_IO_DISABLE is set when bcache is stopping the whold cache set, all 508 * external and internal I/O should be denied when this flag is set. 509 * 510 */ 511#define CACHE_SET_UNREGISTERING 0 512#define CACHE_SET_STOPPING 1 513#define CACHE_SET_RUNNING 2 514#define CACHE_SET_IO_DISABLE 3 515 516struct cache_set { 517 struct closure cl; 518 519 struct list_head list; 520 struct kobject kobj; 521 struct kobject internal; 522 struct dentry *debug; 523 struct cache_accounting accounting; 524 525 unsigned long flags; 526 atomic_t idle_counter; 527 atomic_t at_max_writeback_rate; 528 529 struct cache *cache; 530 531 struct bcache_device **devices; 532 unsigned int devices_max_used; 533 atomic_t attached_dev_nr; 534 struct list_head cached_devs; 535 uint64_t cached_dev_sectors; 536 atomic_long_t flash_dev_dirty_sectors; 537 struct closure caching; 538 539 struct closure sb_write; 540 struct semaphore sb_write_mutex; 541 542 mempool_t search; 543 mempool_t bio_meta; 544 struct bio_set bio_split; 545 546 /* For the btree cache */ 547 struct shrinker *shrink; 548 549 /* For the btree cache and anything allocation related */ 550 struct mutex bucket_lock; 551 552 /* log2(bucket_size), in sectors */ 553 unsigned short bucket_bits; 554 555 /* log2(block_size), in sectors */ 556 unsigned short block_bits; 557 558 /* 559 * Default number of pages for a new btree node - may be less than a 560 * full bucket 561 */ 562 unsigned int btree_pages; 563 564 /* 565 * Lists of struct btrees; lru is the list for structs that have memory 566 * allocated for actual btree node, freed is for structs that do not. 567 * 568 * We never free a struct btree, except on shutdown - we just put it on 569 * the btree_cache_freed list and reuse it later. This simplifies the 570 * code, and it doesn't cost us much memory as the memory usage is 571 * dominated by buffers that hold the actual btree node data and those 572 * can be freed - and the number of struct btrees allocated is 573 * effectively bounded. 574 * 575 * btree_cache_freeable effectively is a small cache - we use it because 576 * high order page allocations can be rather expensive, and it's quite 577 * common to delete and allocate btree nodes in quick succession. It 578 * should never grow past ~2-3 nodes in practice. 579 */ 580 struct list_head btree_cache; 581 struct list_head btree_cache_freeable; 582 struct list_head btree_cache_freed; 583 584 /* Number of elements in btree_cache + btree_cache_freeable lists */ 585 unsigned int btree_cache_used; 586 587 /* 588 * If we need to allocate memory for a new btree node and that 589 * allocation fails, we can cannibalize another node in the btree cache 590 * to satisfy the allocation - lock to guarantee only one thread does 591 * this at a time: 592 */ 593 wait_queue_head_t btree_cache_wait; 594 struct task_struct *btree_cache_alloc_lock; 595 spinlock_t btree_cannibalize_lock; 596 597 /* 598 * When we free a btree node, we increment the gen of the bucket the 599 * node is in - but we can't rewrite the prios and gens until we 600 * finished whatever it is we were doing, otherwise after a crash the 601 * btree node would be freed but for say a split, we might not have the 602 * pointers to the new nodes inserted into the btree yet. 603 * 604 * This is a refcount that blocks prio_write() until the new keys are 605 * written. 606 */ 607 atomic_t prio_blocked; 608 wait_queue_head_t bucket_wait; 609 610 /* 611 * For any bio we don't skip we subtract the number of sectors from 612 * rescale; when it hits 0 we rescale all the bucket priorities. 613 */ 614 atomic_t rescale; 615 /* 616 * used for GC, identify if any front side I/Os is inflight 617 */ 618 atomic_t search_inflight; 619 /* 620 * When we invalidate buckets, we use both the priority and the amount 621 * of good data to determine which buckets to reuse first - to weight 622 * those together consistently we keep track of the smallest nonzero 623 * priority of any bucket. 624 */ 625 uint16_t min_prio; 626 627 /* 628 * max(gen - last_gc) for all buckets. When it gets too big we have to 629 * gc to keep gens from wrapping around. 630 */ 631 uint8_t need_gc; 632 struct gc_stat gc_stats; 633 size_t nbuckets; 634 size_t avail_nbuckets; 635 636 struct task_struct *gc_thread; 637 /* Where in the btree gc currently is */ 638 struct bkey gc_done; 639 640 /* 641 * For automatical garbage collection after writeback completed, this 642 * varialbe is used as bit fields, 643 * - 0000 0001b (BCH_ENABLE_AUTO_GC): enable gc after writeback 644 * - 0000 0010b (BCH_DO_AUTO_GC): do gc after writeback 645 * This is an optimization for following write request after writeback 646 * finished, but read hit rate dropped due to clean data on cache is 647 * discarded. Unless user explicitly sets it via sysfs, it won't be 648 * enabled. 649 */ 650#define BCH_ENABLE_AUTO_GC 1 651#define BCH_DO_AUTO_GC 2 652 uint8_t gc_after_writeback; 653 654 /* 655 * The allocation code needs gc_mark in struct bucket to be correct, but 656 * it's not while a gc is in progress. Protected by bucket_lock. 657 */ 658 int gc_mark_valid; 659 660 /* Counts how many sectors bio_insert has added to the cache */ 661 atomic_t sectors_to_gc; 662 wait_queue_head_t gc_wait; 663 664 struct keybuf moving_gc_keys; 665 /* Number of moving GC bios in flight */ 666 struct semaphore moving_in_flight; 667 668 struct workqueue_struct *moving_gc_wq; 669 670 struct btree *root; 671 672#ifdef CONFIG_BCACHE_DEBUG 673 struct btree *verify_data; 674 struct bset *verify_ondisk; 675 struct mutex verify_lock; 676#endif 677 678 uint8_t set_uuid[16]; 679 unsigned int nr_uuids; 680 struct uuid_entry *uuids; 681 BKEY_PADDED(uuid_bucket); 682 struct closure uuid_write; 683 struct semaphore uuid_write_mutex; 684 685 /* 686 * A btree node on disk could have too many bsets for an iterator to fit 687 * on the stack - have to dynamically allocate them. 688 * bch_cache_set_alloc() will make sure the pool can allocate iterators 689 * equipped with enough room that can host 690 * (sb.bucket_size / sb.block_size) 691 * btree_iter_sets, which is more than static MAX_BSETS. 692 */ 693 mempool_t fill_iter; 694 695 struct bset_sort_state sort; 696 697 /* List of buckets we're currently writing data to */ 698 struct list_head data_buckets; 699 spinlock_t data_bucket_lock; 700 701 struct journal journal; 702 703#define CONGESTED_MAX 1024 704 unsigned int congested_last_us; 705 atomic_t congested; 706 707 /* The rest of this all shows up in sysfs */ 708 unsigned int congested_read_threshold_us; 709 unsigned int congested_write_threshold_us; 710 711 struct time_stats btree_gc_time; 712 struct time_stats btree_split_time; 713 struct time_stats btree_read_time; 714 715 atomic_long_t cache_read_races; 716 atomic_long_t writeback_keys_done; 717 atomic_long_t writeback_keys_failed; 718 719 atomic_long_t reclaim; 720 atomic_long_t reclaimed_journal_buckets; 721 atomic_long_t flush_write; 722 723 enum { 724 ON_ERROR_UNREGISTER, 725 ON_ERROR_PANIC, 726 } on_error; 727#define DEFAULT_IO_ERROR_LIMIT 8 728 unsigned int error_limit; 729 unsigned int error_decay; 730 731 unsigned short journal_delay_ms; 732 bool expensive_debug_checks; 733 unsigned int verify:1; 734 unsigned int key_merging_disabled:1; 735 unsigned int gc_always_rewrite:1; 736 unsigned int shrinker_disabled:1; 737 unsigned int copy_gc_enabled:1; 738 unsigned int idle_max_writeback_rate_enabled:1; 739 740#define BUCKET_HASH_BITS 12 741 struct hlist_head bucket_hash[1 << BUCKET_HASH_BITS]; 742}; 743 744struct bbio { 745 unsigned int submit_time_us; 746 union { 747 struct bkey key; 748 uint64_t _pad[3]; 749 /* 750 * We only need pad = 3 here because we only ever carry around a 751 * single pointer - i.e. the pointer we're doing io to/from. 752 */ 753 }; 754 struct bio bio; 755}; 756 757#define BTREE_PRIO USHRT_MAX 758#define INITIAL_PRIO 32768U 759 760#define btree_bytes(c) ((c)->btree_pages * PAGE_SIZE) 761#define btree_blocks(b) \ 762 ((unsigned int) (KEY_SIZE(&b->key) >> (b)->c->block_bits)) 763 764#define btree_default_blocks(c) \ 765 ((unsigned int) ((PAGE_SECTORS * (c)->btree_pages) >> (c)->block_bits)) 766 767#define bucket_bytes(ca) ((ca)->sb.bucket_size << 9) 768#define block_bytes(ca) ((ca)->sb.block_size << 9) 769 770static inline unsigned int meta_bucket_pages(struct cache_sb *sb) 771{ 772 unsigned int n, max_pages; 773 774 max_pages = min_t(unsigned int, 775 __rounddown_pow_of_two(USHRT_MAX) / PAGE_SECTORS, 776 MAX_ORDER_NR_PAGES); 777 778 n = sb->bucket_size / PAGE_SECTORS; 779 if (n > max_pages) 780 n = max_pages; 781 782 return n; 783} 784 785static inline unsigned int meta_bucket_bytes(struct cache_sb *sb) 786{ 787 return meta_bucket_pages(sb) << PAGE_SHIFT; 788} 789 790#define prios_per_bucket(ca) \ 791 ((meta_bucket_bytes(&(ca)->sb) - sizeof(struct prio_set)) / \ 792 sizeof(struct bucket_disk)) 793 794#define prio_buckets(ca) \ 795 DIV_ROUND_UP((size_t) (ca)->sb.nbuckets, prios_per_bucket(ca)) 796 797static inline size_t sector_to_bucket(struct cache_set *c, sector_t s) 798{ 799 return s >> c->bucket_bits; 800} 801 802static inline sector_t bucket_to_sector(struct cache_set *c, size_t b) 803{ 804 return ((sector_t) b) << c->bucket_bits; 805} 806 807static inline sector_t bucket_remainder(struct cache_set *c, sector_t s) 808{ 809 return s & (c->cache->sb.bucket_size - 1); 810} 811 812static inline size_t PTR_BUCKET_NR(struct cache_set *c, 813 const struct bkey *k, 814 unsigned int ptr) 815{ 816 return sector_to_bucket(c, PTR_OFFSET(k, ptr)); 817} 818 819static inline struct bucket *PTR_BUCKET(struct cache_set *c, 820 const struct bkey *k, 821 unsigned int ptr) 822{ 823 return c->cache->buckets + PTR_BUCKET_NR(c, k, ptr); 824} 825 826static inline uint8_t gen_after(uint8_t a, uint8_t b) 827{ 828 uint8_t r = a - b; 829 830 return r > 128U ? 0 : r; 831} 832 833static inline uint8_t ptr_stale(struct cache_set *c, const struct bkey *k, 834 unsigned int i) 835{ 836 return gen_after(PTR_BUCKET(c, k, i)->gen, PTR_GEN(k, i)); 837} 838 839static inline bool ptr_available(struct cache_set *c, const struct bkey *k, 840 unsigned int i) 841{ 842 return (PTR_DEV(k, i) < MAX_CACHES_PER_SET) && c->cache; 843} 844 845/* Btree key macros */ 846 847/* 848 * This is used for various on disk data structures - cache_sb, prio_set, bset, 849 * jset: The checksum is _always_ the first 8 bytes of these structs 850 */ 851#define csum_set(i) \ 852 bch_crc64(((void *) (i)) + sizeof(uint64_t), \ 853 ((void *) bset_bkey_last(i)) - \ 854 (((void *) (i)) + sizeof(uint64_t))) 855 856/* Error handling macros */ 857 858#define btree_bug(b, ...) \ 859do { \ 860 if (bch_cache_set_error((b)->c, __VA_ARGS__)) \ 861 dump_stack(); \ 862} while (0) 863 864#define cache_bug(c, ...) \ 865do { \ 866 if (bch_cache_set_error(c, __VA_ARGS__)) \ 867 dump_stack(); \ 868} while (0) 869 870#define btree_bug_on(cond, b, ...) \ 871do { \ 872 if (cond) \ 873 btree_bug(b, __VA_ARGS__); \ 874} while (0) 875 876#define cache_bug_on(cond, c, ...) \ 877do { \ 878 if (cond) \ 879 cache_bug(c, __VA_ARGS__); \ 880} while (0) 881 882#define cache_set_err_on(cond, c, ...) \ 883do { \ 884 if (cond) \ 885 bch_cache_set_error(c, __VA_ARGS__); \ 886} while (0) 887 888/* Looping macros */ 889 890#define for_each_bucket(b, ca) \ 891 for (b = (ca)->buckets + (ca)->sb.first_bucket; \ 892 b < (ca)->buckets + (ca)->sb.nbuckets; b++) 893 894static inline void cached_dev_put(struct cached_dev *dc) 895{ 896 if (refcount_dec_and_test(&dc->count)) 897 schedule_work(&dc->detach); 898} 899 900static inline bool cached_dev_get(struct cached_dev *dc) 901{ 902 if (!refcount_inc_not_zero(&dc->count)) 903 return false; 904 905 /* Paired with the mb in cached_dev_attach */ 906 smp_mb__after_atomic(); 907 return true; 908} 909 910/* 911 * bucket_gc_gen() returns the difference between the bucket's current gen and 912 * the oldest gen of any pointer into that bucket in the btree (last_gc). 913 */ 914 915static inline uint8_t bucket_gc_gen(struct bucket *b) 916{ 917 return b->gen - b->last_gc; 918} 919 920#define BUCKET_GC_GEN_MAX 96U 921 922#define kobj_attribute_write(n, fn) \ 923 static struct kobj_attribute ksysfs_##n = __ATTR(n, 0200, NULL, fn) 924 925#define kobj_attribute_rw(n, show, store) \ 926 static struct kobj_attribute ksysfs_##n = \ 927 __ATTR(n, 0600, show, store) 928 929static inline void wake_up_allocators(struct cache_set *c) 930{ 931 struct cache *ca = c->cache; 932 933 wake_up_process(ca->alloc_thread); 934} 935 936static inline void closure_bio_submit(struct cache_set *c, 937 struct bio *bio, 938 struct closure *cl) 939{ 940 closure_get(cl); 941 if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &c->flags))) { 942 bio->bi_status = BLK_STS_IOERR; 943 bio_endio(bio); 944 return; 945 } 946 submit_bio_noacct(bio); 947} 948 949/* 950 * Prevent the kthread exits directly, and make sure when kthread_stop() 951 * is called to stop a kthread, it is still alive. If a kthread might be 952 * stopped by CACHE_SET_IO_DISABLE bit set, wait_for_kthread_stop() is 953 * necessary before the kthread returns. 954 */ 955static inline void wait_for_kthread_stop(void) 956{ 957 while (!kthread_should_stop()) { 958 set_current_state(TASK_INTERRUPTIBLE); 959 schedule(); 960 } 961} 962 963/* Forward declarations */ 964 965void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio); 966void bch_count_io_errors(struct cache *ca, blk_status_t error, 967 int is_read, const char *m); 968void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio, 969 blk_status_t error, const char *m); 970void bch_bbio_endio(struct cache_set *c, struct bio *bio, 971 blk_status_t error, const char *m); 972void bch_bbio_free(struct bio *bio, struct cache_set *c); 973struct bio *bch_bbio_alloc(struct cache_set *c); 974 975void __bch_submit_bbio(struct bio *bio, struct cache_set *c); 976void bch_submit_bbio(struct bio *bio, struct cache_set *c, 977 struct bkey *k, unsigned int ptr); 978 979uint8_t bch_inc_gen(struct cache *ca, struct bucket *b); 980void bch_rescale_priorities(struct cache_set *c, int sectors); 981 982bool bch_can_invalidate_bucket(struct cache *ca, struct bucket *b); 983void __bch_invalidate_one_bucket(struct cache *ca, struct bucket *b); 984 985void __bch_bucket_free(struct cache *ca, struct bucket *b); 986void bch_bucket_free(struct cache_set *c, struct bkey *k); 987 988long bch_bucket_alloc(struct cache *ca, unsigned int reserve, bool wait); 989int __bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve, 990 struct bkey *k, bool wait); 991int bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve, 992 struct bkey *k, bool wait); 993bool bch_alloc_sectors(struct cache_set *c, struct bkey *k, 994 unsigned int sectors, unsigned int write_point, 995 unsigned int write_prio, bool wait); 996bool bch_cached_dev_error(struct cached_dev *dc); 997 998__printf(2, 3) 999bool bch_cache_set_error(struct cache_set *c, const char *fmt, ...); 1000 1001int bch_prio_write(struct cache *ca, bool wait); 1002void bch_write_bdev_super(struct cached_dev *dc, struct closure *parent); 1003 1004extern struct workqueue_struct *bcache_wq; 1005extern struct workqueue_struct *bch_journal_wq; 1006extern struct workqueue_struct *bch_flush_wq; 1007extern struct mutex bch_register_lock; 1008extern struct list_head bch_cache_sets; 1009 1010extern const struct kobj_type bch_cached_dev_ktype; 1011extern const struct kobj_type bch_flash_dev_ktype; 1012extern const struct kobj_type bch_cache_set_ktype; 1013extern const struct kobj_type bch_cache_set_internal_ktype; 1014extern const struct kobj_type bch_cache_ktype; 1015 1016void bch_cached_dev_release(struct kobject *kobj); 1017void bch_flash_dev_release(struct kobject *kobj); 1018void bch_cache_set_release(struct kobject *kobj); 1019void bch_cache_release(struct kobject *kobj); 1020 1021int bch_uuid_write(struct cache_set *c); 1022void bcache_write_super(struct cache_set *c); 1023 1024int bch_flash_dev_create(struct cache_set *c, uint64_t size); 1025 1026int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c, 1027 uint8_t *set_uuid); 1028void bch_cached_dev_detach(struct cached_dev *dc); 1029int bch_cached_dev_run(struct cached_dev *dc); 1030void bcache_device_stop(struct bcache_device *d); 1031 1032void bch_cache_set_unregister(struct cache_set *c); 1033void bch_cache_set_stop(struct cache_set *c); 1034 1035struct cache_set *bch_cache_set_alloc(struct cache_sb *sb); 1036void bch_btree_cache_free(struct cache_set *c); 1037int bch_btree_cache_alloc(struct cache_set *c); 1038void bch_moving_init_cache_set(struct cache_set *c); 1039int bch_open_buckets_alloc(struct cache_set *c); 1040void bch_open_buckets_free(struct cache_set *c); 1041 1042int bch_cache_allocator_start(struct cache *ca); 1043 1044void bch_debug_exit(void); 1045void bch_debug_init(void); 1046void bch_request_exit(void); 1047int bch_request_init(void); 1048void bch_btree_exit(void); 1049int bch_btree_init(void); 1050 1051#endif /* _BCACHE_H */ 1052