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 "\n", __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" 196 197 struct 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 */ 209 210 BITMASK(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)) 216 BITMASK(GC_SECTORS_USED, struct bucket, gc_mark, 2, GC_SECTORS_USED_SIZE); 217 BITMASK(GC_MOVE, struct bucket, gc_mark, 15, 1); 218 219 #include "journal.h" 220 #include "stats.h" 221 struct search; 222 struct btree; 223 struct keybuf; 224 225 struct keybuf_key { 226 struct rb_node node; 227 BKEY_PADDED(key); 228 void *private; 229 }; 230 231 struct 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 }; 248 249 struct bcache_device { 250 struct closure cl; 251 252 struct kobject kobj; 253 254 struct cache_set *c; 255 unsigned 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 unsigned nr_stripes; 268 unsigned stripe_size; 269 atomic_t *stripe_sectors_dirty; 270 unsigned long *full_dirty_stripes; 271 272 struct bio_set *bio_split; 273 274 unsigned data_csum:1; 275 276 int (*cache_miss)(struct btree *, struct search *, 277 struct bio *, unsigned); 278 int (*ioctl) (struct bcache_device *, fmode_t, unsigned, unsigned long); 279 }; 280 281 struct io { 282 /* Used to track sequential IO so it can be skipped */ 283 struct hlist_node hash; 284 struct list_head lru; 285 286 unsigned long jiffies; 287 unsigned sequential; 288 sector_t last; 289 }; 290 291 enum stop_on_failure { 292 BCH_CACHED_DEV_STOP_AUTO = 0, 293 BCH_CACHED_DEV_STOP_ALWAYS, 294 BCH_CACHED_DEV_STOP_MODE_MAX, 295 }; 296 297 struct cached_dev { 298 struct list_head list; 299 struct bcache_device disk; 300 struct block_device *bdev; 301 302 struct cache_sb sb; 303 struct bio sb_bio; 304 struct bio_vec sb_bv[1]; 305 struct closure sb_write; 306 struct semaphore sb_write_mutex; 307 308 /* Refcount on the cache set. Always nonzero when we're caching. */ 309 refcount_t count; 310 struct work_struct detach; 311 312 /* 313 * Device might not be running if it's dirty and the cache set hasn't 314 * showed up yet. 315 */ 316 atomic_t running; 317 318 /* 319 * Writes take a shared lock from start to finish; scanning for dirty 320 * data to refill the rb tree requires an exclusive lock. 321 */ 322 struct rw_semaphore writeback_lock; 323 324 /* 325 * Nonzero, and writeback has a refcount (d->count), iff there is dirty 326 * data in the cache. Protected by writeback_lock; must have an 327 * shared lock to set and exclusive lock to clear. 328 */ 329 atomic_t has_dirty; 330 331 /* 332 * Set to zero by things that touch the backing volume-- except 333 * writeback. Incremented by writeback. Used to determine when to 334 * accelerate idle writeback. 335 */ 336 atomic_t backing_idle; 337 338 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 /* 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 sequential_cutoff; 368 unsigned readahead; 369 370 unsigned io_disable:1; 371 unsigned verify:1; 372 unsigned bypass_torture_test:1; 373 374 unsigned partial_stripes_expensive:1; 375 unsigned writeback_metadata:1; 376 unsigned writeback_running:1; 377 unsigned char writeback_percent; 378 unsigned 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 writeback_rate_update_seconds; 387 unsigned writeback_rate_i_term_inverse; 388 unsigned writeback_rate_p_term_inverse; 389 unsigned 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 error_limit; 395 396 char backing_dev_name[BDEVNAME_SIZE]; 397 }; 398 399 enum alloc_reserve { 400 RESERVE_BTREE, 401 RESERVE_PRIO, 402 RESERVE_MOVINGGC, 403 RESERVE_NONE, 404 RESERVE_NR, 405 }; 406 407 struct cache { 408 struct cache_set *set; 409 struct cache_sb sb; 410 struct bio sb_bio; 411 struct bio_vec sb_bv[1]; 412 413 struct kobject kobj; 414 struct block_device *bdev; 415 416 struct task_struct *alloc_thread; 417 418 struct closure prio; 419 struct prio_set *disk_buckets; 420 421 /* 422 * When allocating new buckets, prio_write() gets first dibs - since we 423 * may not be allocate at all without writing priorities and gens. 424 * prio_buckets[] contains the last buckets we wrote priorities to (so 425 * gc can mark them as metadata), prio_next[] contains the buckets 426 * allocated for the next prio write. 427 */ 428 uint64_t *prio_buckets; 429 uint64_t *prio_last_buckets; 430 431 /* 432 * free: Buckets that are ready to be used 433 * 434 * free_inc: Incoming buckets - these are buckets that currently have 435 * cached data in them, and we can't reuse them until after we write 436 * their new gen to disk. After prio_write() finishes writing the new 437 * gens/prios, they'll be moved to the free list (and possibly discarded 438 * in the process) 439 */ 440 DECLARE_FIFO(long, free)[RESERVE_NR]; 441 DECLARE_FIFO(long, free_inc); 442 443 size_t fifo_last_bucket; 444 445 /* Allocation stuff: */ 446 struct bucket *buckets; 447 448 DECLARE_HEAP(struct bucket *, heap); 449 450 /* 451 * If nonzero, we know we aren't going to find any buckets to invalidate 452 * until a gc finishes - otherwise we could pointlessly burn a ton of 453 * cpu 454 */ 455 unsigned invalidate_needs_gc; 456 457 bool discard; /* Get rid of? */ 458 459 struct journal_device journal; 460 461 /* The rest of this all shows up in sysfs */ 462 #define IO_ERROR_SHIFT 20 463 atomic_t io_errors; 464 atomic_t io_count; 465 466 atomic_long_t meta_sectors_written; 467 atomic_long_t btree_sectors_written; 468 atomic_long_t sectors_written; 469 470 char cache_dev_name[BDEVNAME_SIZE]; 471 }; 472 473 struct gc_stat { 474 size_t nodes; 475 size_t key_bytes; 476 477 size_t nkeys; 478 uint64_t data; /* sectors */ 479 unsigned in_use; /* percent */ 480 }; 481 482 /* 483 * Flag bits, for how the cache set is shutting down, and what phase it's at: 484 * 485 * CACHE_SET_UNREGISTERING means we're not just shutting down, we're detaching 486 * all the backing devices first (their cached data gets invalidated, and they 487 * won't automatically reattach). 488 * 489 * CACHE_SET_STOPPING always gets set first when we're closing down a cache set; 490 * we'll continue to run normally for awhile with CACHE_SET_STOPPING set (i.e. 491 * flushing dirty data). 492 * 493 * CACHE_SET_RUNNING means all cache devices have been registered and journal 494 * replay is complete. 495 * 496 * CACHE_SET_IO_DISABLE is set when bcache is stopping the whold cache set, all 497 * external and internal I/O should be denied when this flag is set. 498 * 499 */ 500 #define CACHE_SET_UNREGISTERING 0 501 #define CACHE_SET_STOPPING 1 502 #define CACHE_SET_RUNNING 2 503 #define CACHE_SET_IO_DISABLE 3 504 505 struct cache_set { 506 struct closure cl; 507 508 struct list_head list; 509 struct kobject kobj; 510 struct kobject internal; 511 struct dentry *debug; 512 struct cache_accounting accounting; 513 514 unsigned long flags; 515 516 struct cache_sb sb; 517 518 struct cache *cache[MAX_CACHES_PER_SET]; 519 struct cache *cache_by_alloc[MAX_CACHES_PER_SET]; 520 int caches_loaded; 521 522 struct bcache_device **devices; 523 unsigned devices_max_used; 524 struct list_head cached_devs; 525 uint64_t cached_dev_sectors; 526 struct closure caching; 527 528 struct closure sb_write; 529 struct semaphore sb_write_mutex; 530 531 mempool_t *search; 532 mempool_t *bio_meta; 533 struct bio_set *bio_split; 534 535 /* For the btree cache */ 536 struct shrinker shrink; 537 538 /* For the btree cache and anything allocation related */ 539 struct mutex bucket_lock; 540 541 /* log2(bucket_size), in sectors */ 542 unsigned short bucket_bits; 543 544 /* log2(block_size), in sectors */ 545 unsigned short block_bits; 546 547 /* 548 * Default number of pages for a new btree node - may be less than a 549 * full bucket 550 */ 551 unsigned btree_pages; 552 553 /* 554 * Lists of struct btrees; lru is the list for structs that have memory 555 * allocated for actual btree node, freed is for structs that do not. 556 * 557 * We never free a struct btree, except on shutdown - we just put it on 558 * the btree_cache_freed list and reuse it later. This simplifies the 559 * code, and it doesn't cost us much memory as the memory usage is 560 * dominated by buffers that hold the actual btree node data and those 561 * can be freed - and the number of struct btrees allocated is 562 * effectively bounded. 563 * 564 * btree_cache_freeable effectively is a small cache - we use it because 565 * high order page allocations can be rather expensive, and it's quite 566 * common to delete and allocate btree nodes in quick succession. It 567 * should never grow past ~2-3 nodes in practice. 568 */ 569 struct list_head btree_cache; 570 struct list_head btree_cache_freeable; 571 struct list_head btree_cache_freed; 572 573 /* Number of elements in btree_cache + btree_cache_freeable lists */ 574 unsigned btree_cache_used; 575 576 /* 577 * If we need to allocate memory for a new btree node and that 578 * allocation fails, we can cannibalize another node in the btree cache 579 * to satisfy the allocation - lock to guarantee only one thread does 580 * this at a time: 581 */ 582 wait_queue_head_t btree_cache_wait; 583 struct task_struct *btree_cache_alloc_lock; 584 585 /* 586 * When we free a btree node, we increment the gen of the bucket the 587 * node is in - but we can't rewrite the prios and gens until we 588 * finished whatever it is we were doing, otherwise after a crash the 589 * btree node would be freed but for say a split, we might not have the 590 * pointers to the new nodes inserted into the btree yet. 591 * 592 * This is a refcount that blocks prio_write() until the new keys are 593 * written. 594 */ 595 atomic_t prio_blocked; 596 wait_queue_head_t bucket_wait; 597 598 /* 599 * For any bio we don't skip we subtract the number of sectors from 600 * rescale; when it hits 0 we rescale all the bucket priorities. 601 */ 602 atomic_t rescale; 603 /* 604 * When we invalidate buckets, we use both the priority and the amount 605 * of good data to determine which buckets to reuse first - to weight 606 * those together consistently we keep track of the smallest nonzero 607 * priority of any bucket. 608 */ 609 uint16_t min_prio; 610 611 /* 612 * max(gen - last_gc) for all buckets. When it gets too big we have to gc 613 * to keep gens from wrapping around. 614 */ 615 uint8_t need_gc; 616 struct gc_stat gc_stats; 617 size_t nbuckets; 618 size_t avail_nbuckets; 619 620 struct task_struct *gc_thread; 621 /* Where in the btree gc currently is */ 622 struct bkey gc_done; 623 624 /* 625 * The allocation code needs gc_mark in struct bucket to be correct, but 626 * it's not while a gc is in progress. Protected by bucket_lock. 627 */ 628 int gc_mark_valid; 629 630 /* Counts how many sectors bio_insert has added to the cache */ 631 atomic_t sectors_to_gc; 632 wait_queue_head_t gc_wait; 633 634 struct keybuf moving_gc_keys; 635 /* Number of moving GC bios in flight */ 636 struct semaphore moving_in_flight; 637 638 struct workqueue_struct *moving_gc_wq; 639 640 struct btree *root; 641 642 #ifdef CONFIG_BCACHE_DEBUG 643 struct btree *verify_data; 644 struct bset *verify_ondisk; 645 struct mutex verify_lock; 646 #endif 647 648 unsigned nr_uuids; 649 struct uuid_entry *uuids; 650 BKEY_PADDED(uuid_bucket); 651 struct closure uuid_write; 652 struct semaphore uuid_write_mutex; 653 654 /* 655 * A btree node on disk could have too many bsets for an iterator to fit 656 * on the stack - have to dynamically allocate them 657 */ 658 mempool_t *fill_iter; 659 660 struct bset_sort_state sort; 661 662 /* List of buckets we're currently writing data to */ 663 struct list_head data_buckets; 664 spinlock_t data_bucket_lock; 665 666 struct journal journal; 667 668 #define CONGESTED_MAX 1024 669 unsigned congested_last_us; 670 atomic_t congested; 671 672 /* The rest of this all shows up in sysfs */ 673 unsigned congested_read_threshold_us; 674 unsigned congested_write_threshold_us; 675 676 struct time_stats btree_gc_time; 677 struct time_stats btree_split_time; 678 struct time_stats btree_read_time; 679 680 atomic_long_t cache_read_races; 681 atomic_long_t writeback_keys_done; 682 atomic_long_t writeback_keys_failed; 683 684 atomic_long_t reclaim; 685 atomic_long_t flush_write; 686 atomic_long_t retry_flush_write; 687 688 enum { 689 ON_ERROR_UNREGISTER, 690 ON_ERROR_PANIC, 691 } on_error; 692 #define DEFAULT_IO_ERROR_LIMIT 8 693 unsigned error_limit; 694 unsigned error_decay; 695 696 unsigned short journal_delay_ms; 697 bool expensive_debug_checks; 698 unsigned verify:1; 699 unsigned key_merging_disabled:1; 700 unsigned gc_always_rewrite:1; 701 unsigned shrinker_disabled:1; 702 unsigned copy_gc_enabled:1; 703 704 #define BUCKET_HASH_BITS 12 705 struct hlist_head bucket_hash[1 << BUCKET_HASH_BITS]; 706 707 DECLARE_HEAP(struct btree *, flush_btree); 708 }; 709 710 struct bbio { 711 unsigned submit_time_us; 712 union { 713 struct bkey key; 714 uint64_t _pad[3]; 715 /* 716 * We only need pad = 3 here because we only ever carry around a 717 * single pointer - i.e. the pointer we're doing io to/from. 718 */ 719 }; 720 struct bio bio; 721 }; 722 723 #define BTREE_PRIO USHRT_MAX 724 #define INITIAL_PRIO 32768U 725 726 #define btree_bytes(c) ((c)->btree_pages * PAGE_SIZE) 727 #define btree_blocks(b) \ 728 ((unsigned) (KEY_SIZE(&b->key) >> (b)->c->block_bits)) 729 730 #define btree_default_blocks(c) \ 731 ((unsigned) ((PAGE_SECTORS * (c)->btree_pages) >> (c)->block_bits)) 732 733 #define bucket_pages(c) ((c)->sb.bucket_size / PAGE_SECTORS) 734 #define bucket_bytes(c) ((c)->sb.bucket_size << 9) 735 #define block_bytes(c) ((c)->sb.block_size << 9) 736 737 #define prios_per_bucket(c) \ 738 ((bucket_bytes(c) - sizeof(struct prio_set)) / \ 739 sizeof(struct bucket_disk)) 740 #define prio_buckets(c) \ 741 DIV_ROUND_UP((size_t) (c)->sb.nbuckets, prios_per_bucket(c)) 742 743 static inline size_t sector_to_bucket(struct cache_set *c, sector_t s) 744 { 745 return s >> c->bucket_bits; 746 } 747 748 static inline sector_t bucket_to_sector(struct cache_set *c, size_t b) 749 { 750 return ((sector_t) b) << c->bucket_bits; 751 } 752 753 static inline sector_t bucket_remainder(struct cache_set *c, sector_t s) 754 { 755 return s & (c->sb.bucket_size - 1); 756 } 757 758 static inline struct cache *PTR_CACHE(struct cache_set *c, 759 const struct bkey *k, 760 unsigned ptr) 761 { 762 return c->cache[PTR_DEV(k, ptr)]; 763 } 764 765 static inline size_t PTR_BUCKET_NR(struct cache_set *c, 766 const struct bkey *k, 767 unsigned ptr) 768 { 769 return sector_to_bucket(c, PTR_OFFSET(k, ptr)); 770 } 771 772 static inline struct bucket *PTR_BUCKET(struct cache_set *c, 773 const struct bkey *k, 774 unsigned ptr) 775 { 776 return PTR_CACHE(c, k, ptr)->buckets + PTR_BUCKET_NR(c, k, ptr); 777 } 778 779 static inline uint8_t gen_after(uint8_t a, uint8_t b) 780 { 781 uint8_t r = a - b; 782 return r > 128U ? 0 : r; 783 } 784 785 static inline uint8_t ptr_stale(struct cache_set *c, const struct bkey *k, 786 unsigned i) 787 { 788 return gen_after(PTR_BUCKET(c, k, i)->gen, PTR_GEN(k, i)); 789 } 790 791 static inline bool ptr_available(struct cache_set *c, const struct bkey *k, 792 unsigned i) 793 { 794 return (PTR_DEV(k, i) < MAX_CACHES_PER_SET) && PTR_CACHE(c, k, i); 795 } 796 797 /* Btree key macros */ 798 799 /* 800 * This is used for various on disk data structures - cache_sb, prio_set, bset, 801 * jset: The checksum is _always_ the first 8 bytes of these structs 802 */ 803 #define csum_set(i) \ 804 bch_crc64(((void *) (i)) + sizeof(uint64_t), \ 805 ((void *) bset_bkey_last(i)) - \ 806 (((void *) (i)) + sizeof(uint64_t))) 807 808 /* Error handling macros */ 809 810 #define btree_bug(b, ...) \ 811 do { \ 812 if (bch_cache_set_error((b)->c, __VA_ARGS__)) \ 813 dump_stack(); \ 814 } while (0) 815 816 #define cache_bug(c, ...) \ 817 do { \ 818 if (bch_cache_set_error(c, __VA_ARGS__)) \ 819 dump_stack(); \ 820 } while (0) 821 822 #define btree_bug_on(cond, b, ...) \ 823 do { \ 824 if (cond) \ 825 btree_bug(b, __VA_ARGS__); \ 826 } while (0) 827 828 #define cache_bug_on(cond, c, ...) \ 829 do { \ 830 if (cond) \ 831 cache_bug(c, __VA_ARGS__); \ 832 } while (0) 833 834 #define cache_set_err_on(cond, c, ...) \ 835 do { \ 836 if (cond) \ 837 bch_cache_set_error(c, __VA_ARGS__); \ 838 } while (0) 839 840 /* Looping macros */ 841 842 #define for_each_cache(ca, cs, iter) \ 843 for (iter = 0; ca = cs->cache[iter], iter < (cs)->sb.nr_in_set; iter++) 844 845 #define for_each_bucket(b, ca) \ 846 for (b = (ca)->buckets + (ca)->sb.first_bucket; \ 847 b < (ca)->buckets + (ca)->sb.nbuckets; b++) 848 849 static inline void cached_dev_put(struct cached_dev *dc) 850 { 851 if (refcount_dec_and_test(&dc->count)) 852 schedule_work(&dc->detach); 853 } 854 855 static inline bool cached_dev_get(struct cached_dev *dc) 856 { 857 if (!refcount_inc_not_zero(&dc->count)) 858 return false; 859 860 /* Paired with the mb in cached_dev_attach */ 861 smp_mb__after_atomic(); 862 return true; 863 } 864 865 /* 866 * bucket_gc_gen() returns the difference between the bucket's current gen and 867 * the oldest gen of any pointer into that bucket in the btree (last_gc). 868 */ 869 870 static inline uint8_t bucket_gc_gen(struct bucket *b) 871 { 872 return b->gen - b->last_gc; 873 } 874 875 #define BUCKET_GC_GEN_MAX 96U 876 877 #define kobj_attribute_write(n, fn) \ 878 static struct kobj_attribute ksysfs_##n = __ATTR(n, S_IWUSR, NULL, fn) 879 880 #define kobj_attribute_rw(n, show, store) \ 881 static struct kobj_attribute ksysfs_##n = \ 882 __ATTR(n, S_IWUSR|S_IRUSR, show, store) 883 884 static inline void wake_up_allocators(struct cache_set *c) 885 { 886 struct cache *ca; 887 unsigned i; 888 889 for_each_cache(ca, c, i) 890 wake_up_process(ca->alloc_thread); 891 } 892 893 static inline void closure_bio_submit(struct cache_set *c, 894 struct bio *bio, 895 struct closure *cl) 896 { 897 closure_get(cl); 898 if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &c->flags))) { 899 bio->bi_status = BLK_STS_IOERR; 900 bio_endio(bio); 901 return; 902 } 903 generic_make_request(bio); 904 } 905 906 /* 907 * Prevent the kthread exits directly, and make sure when kthread_stop() 908 * is called to stop a kthread, it is still alive. If a kthread might be 909 * stopped by CACHE_SET_IO_DISABLE bit set, wait_for_kthread_stop() is 910 * necessary before the kthread returns. 911 */ 912 static inline void wait_for_kthread_stop(void) 913 { 914 while (!kthread_should_stop()) { 915 set_current_state(TASK_INTERRUPTIBLE); 916 schedule(); 917 } 918 } 919 920 /* Forward declarations */ 921 922 void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio); 923 void bch_count_io_errors(struct cache *, blk_status_t, int, const char *); 924 void bch_bbio_count_io_errors(struct cache_set *, struct bio *, 925 blk_status_t, const char *); 926 void bch_bbio_endio(struct cache_set *, struct bio *, blk_status_t, 927 const char *); 928 void bch_bbio_free(struct bio *, struct cache_set *); 929 struct bio *bch_bbio_alloc(struct cache_set *); 930 931 void __bch_submit_bbio(struct bio *, struct cache_set *); 932 void bch_submit_bbio(struct bio *, struct cache_set *, struct bkey *, unsigned); 933 934 uint8_t bch_inc_gen(struct cache *, struct bucket *); 935 void bch_rescale_priorities(struct cache_set *, int); 936 937 bool bch_can_invalidate_bucket(struct cache *, struct bucket *); 938 void __bch_invalidate_one_bucket(struct cache *, struct bucket *); 939 940 void __bch_bucket_free(struct cache *, struct bucket *); 941 void bch_bucket_free(struct cache_set *, struct bkey *); 942 943 long bch_bucket_alloc(struct cache *, unsigned, bool); 944 int __bch_bucket_alloc_set(struct cache_set *, unsigned, 945 struct bkey *, int, bool); 946 int bch_bucket_alloc_set(struct cache_set *, unsigned, 947 struct bkey *, int, bool); 948 bool bch_alloc_sectors(struct cache_set *, struct bkey *, unsigned, 949 unsigned, unsigned, bool); 950 bool bch_cached_dev_error(struct cached_dev *dc); 951 952 __printf(2, 3) 953 bool bch_cache_set_error(struct cache_set *, const char *, ...); 954 955 void bch_prio_write(struct cache *); 956 void bch_write_bdev_super(struct cached_dev *, struct closure *); 957 958 extern struct workqueue_struct *bcache_wq; 959 extern const char * const bch_cache_modes[]; 960 extern const char * const bch_stop_on_failure_modes[]; 961 extern struct mutex bch_register_lock; 962 extern struct list_head bch_cache_sets; 963 964 extern struct kobj_type bch_cached_dev_ktype; 965 extern struct kobj_type bch_flash_dev_ktype; 966 extern struct kobj_type bch_cache_set_ktype; 967 extern struct kobj_type bch_cache_set_internal_ktype; 968 extern struct kobj_type bch_cache_ktype; 969 970 void bch_cached_dev_release(struct kobject *); 971 void bch_flash_dev_release(struct kobject *); 972 void bch_cache_set_release(struct kobject *); 973 void bch_cache_release(struct kobject *); 974 975 int bch_uuid_write(struct cache_set *); 976 void bcache_write_super(struct cache_set *); 977 978 int bch_flash_dev_create(struct cache_set *c, uint64_t size); 979 980 int bch_cached_dev_attach(struct cached_dev *, struct cache_set *, uint8_t *); 981 void bch_cached_dev_detach(struct cached_dev *); 982 void bch_cached_dev_run(struct cached_dev *); 983 void bcache_device_stop(struct bcache_device *); 984 985 void bch_cache_set_unregister(struct cache_set *); 986 void bch_cache_set_stop(struct cache_set *); 987 988 struct cache_set *bch_cache_set_alloc(struct cache_sb *); 989 void bch_btree_cache_free(struct cache_set *); 990 int bch_btree_cache_alloc(struct cache_set *); 991 void bch_moving_init_cache_set(struct cache_set *); 992 int bch_open_buckets_alloc(struct cache_set *); 993 void bch_open_buckets_free(struct cache_set *); 994 995 int bch_cache_allocator_start(struct cache *ca); 996 997 void bch_debug_exit(void); 998 int bch_debug_init(struct kobject *); 999 void bch_request_exit(void); 1000 int bch_request_init(void); 1001 1002 #endif /* _BCACHE_H */ 1003