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 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 unsigned int nr_stripes; 268 unsigned int stripe_size; 269 atomic_t *stripe_sectors_dirty; 270 unsigned long *full_dirty_stripes; 271 272 struct bio_set bio_split; 273 274 unsigned int data_csum:1; 275 276 int (*cache_miss)(struct btree *b, struct search *s, 277 struct bio *bio, unsigned int sectors); 278 int (*ioctl)(struct bcache_device *d, fmode_t mode, 279 unsigned int cmd, unsigned long arg); 280 }; 281 282 struct io { 283 /* Used to track sequential IO so it can be skipped */ 284 struct hlist_node hash; 285 struct list_head lru; 286 287 unsigned long jiffies; 288 unsigned int sequential; 289 sector_t last; 290 }; 291 292 enum stop_on_failure { 293 BCH_CACHED_DEV_STOP_AUTO = 0, 294 BCH_CACHED_DEV_STOP_ALWAYS, 295 BCH_CACHED_DEV_STOP_MODE_MAX, 296 }; 297 298 struct cached_dev { 299 struct list_head list; 300 struct bcache_device disk; 301 struct block_device *bdev; 302 303 struct cache_sb sb; 304 struct bio sb_bio; 305 struct bio_vec sb_bv[1]; 306 struct closure sb_write; 307 struct semaphore sb_write_mutex; 308 309 /* Refcount on the cache set. Always nonzero when we're caching. */ 310 refcount_t count; 311 struct work_struct detach; 312 313 /* 314 * Device might not be running if it's dirty and the cache set hasn't 315 * showed up yet. 316 */ 317 atomic_t running; 318 319 /* 320 * Writes take a shared lock from start to finish; scanning for dirty 321 * data to refill the rb tree requires an exclusive lock. 322 */ 323 struct rw_semaphore writeback_lock; 324 325 /* 326 * Nonzero, and writeback has a refcount (d->count), iff there is dirty 327 * data in the cache. Protected by writeback_lock; must have an 328 * shared lock to set and exclusive lock to clear. 329 */ 330 atomic_t has_dirty; 331 332 struct bch_ratelimit writeback_rate; 333 struct delayed_work writeback_rate_update; 334 335 /* Limit number of writeback bios in flight */ 336 struct semaphore in_flight; 337 struct task_struct *writeback_thread; 338 struct workqueue_struct *writeback_write_wq; 339 340 struct keybuf writeback_keys; 341 342 struct task_struct *status_update_thread; 343 /* 344 * Order the write-half of writeback operations strongly in dispatch 345 * order. (Maintain LBA order; don't allow reads completing out of 346 * order to re-order the writes...) 347 */ 348 struct closure_waitlist writeback_ordering_wait; 349 atomic_t writeback_sequence_next; 350 351 /* For tracking sequential IO */ 352 #define RECENT_IO_BITS 7 353 #define RECENT_IO (1 << RECENT_IO_BITS) 354 struct io io[RECENT_IO]; 355 struct hlist_head io_hash[RECENT_IO + 1]; 356 struct list_head io_lru; 357 spinlock_t io_lock; 358 359 struct cache_accounting accounting; 360 361 /* The rest of this all shows up in sysfs */ 362 unsigned int sequential_cutoff; 363 unsigned int readahead; 364 365 unsigned int io_disable:1; 366 unsigned int verify:1; 367 unsigned int bypass_torture_test:1; 368 369 unsigned int partial_stripes_expensive:1; 370 unsigned int writeback_metadata:1; 371 unsigned int writeback_running:1; 372 unsigned char writeback_percent; 373 unsigned int writeback_delay; 374 375 uint64_t writeback_rate_target; 376 int64_t writeback_rate_proportional; 377 int64_t writeback_rate_integral; 378 int64_t writeback_rate_integral_scaled; 379 int32_t writeback_rate_change; 380 381 unsigned int writeback_rate_update_seconds; 382 unsigned int writeback_rate_i_term_inverse; 383 unsigned int writeback_rate_p_term_inverse; 384 unsigned int writeback_rate_minimum; 385 386 enum stop_on_failure stop_when_cache_set_failed; 387 #define DEFAULT_CACHED_DEV_ERROR_LIMIT 64 388 atomic_t io_errors; 389 unsigned int error_limit; 390 unsigned int offline_seconds; 391 392 char backing_dev_name[BDEVNAME_SIZE]; 393 }; 394 395 enum alloc_reserve { 396 RESERVE_BTREE, 397 RESERVE_PRIO, 398 RESERVE_MOVINGGC, 399 RESERVE_NONE, 400 RESERVE_NR, 401 }; 402 403 struct cache { 404 struct cache_set *set; 405 struct cache_sb sb; 406 struct bio sb_bio; 407 struct bio_vec sb_bv[1]; 408 409 struct kobject kobj; 410 struct block_device *bdev; 411 412 struct task_struct *alloc_thread; 413 414 struct closure prio; 415 struct prio_set *disk_buckets; 416 417 /* 418 * When allocating new buckets, prio_write() gets first dibs - since we 419 * may not be allocate at all without writing priorities and gens. 420 * prio_last_buckets[] contains the last buckets we wrote priorities to 421 * (so gc can mark them as metadata), prio_buckets[] contains the 422 * buckets allocated for the next prio write. 423 */ 424 uint64_t *prio_buckets; 425 uint64_t *prio_last_buckets; 426 427 /* 428 * free: Buckets that are ready to be used 429 * 430 * free_inc: Incoming buckets - these are buckets that currently have 431 * cached data in them, and we can't reuse them until after we write 432 * their new gen to disk. After prio_write() finishes writing the new 433 * gens/prios, they'll be moved to the free list (and possibly discarded 434 * in the process) 435 */ 436 DECLARE_FIFO(long, free)[RESERVE_NR]; 437 DECLARE_FIFO(long, free_inc); 438 439 size_t fifo_last_bucket; 440 441 /* Allocation stuff: */ 442 struct bucket *buckets; 443 444 DECLARE_HEAP(struct bucket *, heap); 445 446 /* 447 * If nonzero, we know we aren't going to find any buckets to invalidate 448 * until a gc finishes - otherwise we could pointlessly burn a ton of 449 * cpu 450 */ 451 unsigned int invalidate_needs_gc; 452 453 bool discard; /* Get rid of? */ 454 455 struct journal_device journal; 456 457 /* The rest of this all shows up in sysfs */ 458 #define IO_ERROR_SHIFT 20 459 atomic_t io_errors; 460 atomic_t io_count; 461 462 atomic_long_t meta_sectors_written; 463 atomic_long_t btree_sectors_written; 464 atomic_long_t sectors_written; 465 466 char cache_dev_name[BDEVNAME_SIZE]; 467 }; 468 469 struct gc_stat { 470 size_t nodes; 471 size_t nodes_pre; 472 size_t key_bytes; 473 474 size_t nkeys; 475 uint64_t data; /* sectors */ 476 unsigned int in_use; /* percent */ 477 }; 478 479 /* 480 * Flag bits, for how the cache set is shutting down, and what phase it's at: 481 * 482 * CACHE_SET_UNREGISTERING means we're not just shutting down, we're detaching 483 * all the backing devices first (their cached data gets invalidated, and they 484 * won't automatically reattach). 485 * 486 * CACHE_SET_STOPPING always gets set first when we're closing down a cache set; 487 * we'll continue to run normally for awhile with CACHE_SET_STOPPING set (i.e. 488 * flushing dirty data). 489 * 490 * CACHE_SET_RUNNING means all cache devices have been registered and journal 491 * replay is complete. 492 * 493 * CACHE_SET_IO_DISABLE is set when bcache is stopping the whold cache set, all 494 * external and internal I/O should be denied when this flag is set. 495 * 496 */ 497 #define CACHE_SET_UNREGISTERING 0 498 #define CACHE_SET_STOPPING 1 499 #define CACHE_SET_RUNNING 2 500 #define CACHE_SET_IO_DISABLE 3 501 502 struct cache_set { 503 struct closure cl; 504 505 struct list_head list; 506 struct kobject kobj; 507 struct kobject internal; 508 struct dentry *debug; 509 struct cache_accounting accounting; 510 511 unsigned long flags; 512 atomic_t idle_counter; 513 atomic_t at_max_writeback_rate; 514 515 struct cache_sb sb; 516 517 struct cache *cache[MAX_CACHES_PER_SET]; 518 struct cache *cache_by_alloc[MAX_CACHES_PER_SET]; 519 int caches_loaded; 520 521 struct bcache_device **devices; 522 unsigned int devices_max_used; 523 atomic_t attached_dev_nr; 524 struct list_head cached_devs; 525 uint64_t cached_dev_sectors; 526 atomic_long_t flash_dev_dirty_sectors; 527 struct closure caching; 528 529 struct closure sb_write; 530 struct semaphore sb_write_mutex; 531 532 mempool_t search; 533 mempool_t bio_meta; 534 struct bio_set bio_split; 535 536 /* For the btree cache */ 537 struct shrinker shrink; 538 539 /* For the btree cache and anything allocation related */ 540 struct mutex bucket_lock; 541 542 /* log2(bucket_size), in sectors */ 543 unsigned short bucket_bits; 544 545 /* log2(block_size), in sectors */ 546 unsigned short block_bits; 547 548 /* 549 * Default number of pages for a new btree node - may be less than a 550 * full bucket 551 */ 552 unsigned int btree_pages; 553 554 /* 555 * Lists of struct btrees; lru is the list for structs that have memory 556 * allocated for actual btree node, freed is for structs that do not. 557 * 558 * We never free a struct btree, except on shutdown - we just put it on 559 * the btree_cache_freed list and reuse it later. This simplifies the 560 * code, and it doesn't cost us much memory as the memory usage is 561 * dominated by buffers that hold the actual btree node data and those 562 * can be freed - and the number of struct btrees allocated is 563 * effectively bounded. 564 * 565 * btree_cache_freeable effectively is a small cache - we use it because 566 * high order page allocations can be rather expensive, and it's quite 567 * common to delete and allocate btree nodes in quick succession. It 568 * should never grow past ~2-3 nodes in practice. 569 */ 570 struct list_head btree_cache; 571 struct list_head btree_cache_freeable; 572 struct list_head btree_cache_freed; 573 574 /* Number of elements in btree_cache + btree_cache_freeable lists */ 575 unsigned int btree_cache_used; 576 577 /* 578 * If we need to allocate memory for a new btree node and that 579 * allocation fails, we can cannibalize another node in the btree cache 580 * to satisfy the allocation - lock to guarantee only one thread does 581 * this at a time: 582 */ 583 wait_queue_head_t btree_cache_wait; 584 struct task_struct *btree_cache_alloc_lock; 585 586 /* 587 * When we free a btree node, we increment the gen of the bucket the 588 * node is in - but we can't rewrite the prios and gens until we 589 * finished whatever it is we were doing, otherwise after a crash the 590 * btree node would be freed but for say a split, we might not have the 591 * pointers to the new nodes inserted into the btree yet. 592 * 593 * This is a refcount that blocks prio_write() until the new keys are 594 * written. 595 */ 596 atomic_t prio_blocked; 597 wait_queue_head_t bucket_wait; 598 599 /* 600 * For any bio we don't skip we subtract the number of sectors from 601 * rescale; when it hits 0 we rescale all the bucket priorities. 602 */ 603 atomic_t rescale; 604 /* 605 * used for GC, identify if any front side I/Os is inflight 606 */ 607 atomic_t search_inflight; 608 /* 609 * When we invalidate buckets, we use both the priority and the amount 610 * of good data to determine which buckets to reuse first - to weight 611 * those together consistently we keep track of the smallest nonzero 612 * priority of any bucket. 613 */ 614 uint16_t min_prio; 615 616 /* 617 * max(gen - last_gc) for all buckets. When it gets too big we have to 618 * gc to keep gens from wrapping around. 619 */ 620 uint8_t need_gc; 621 struct gc_stat gc_stats; 622 size_t nbuckets; 623 size_t avail_nbuckets; 624 625 struct task_struct *gc_thread; 626 /* Where in the btree gc currently is */ 627 struct bkey gc_done; 628 629 /* 630 * The allocation code needs gc_mark in struct bucket to be correct, but 631 * it's not while a gc is in progress. Protected by bucket_lock. 632 */ 633 int gc_mark_valid; 634 635 /* Counts how many sectors bio_insert has added to the cache */ 636 atomic_t sectors_to_gc; 637 wait_queue_head_t gc_wait; 638 639 struct keybuf moving_gc_keys; 640 /* Number of moving GC bios in flight */ 641 struct semaphore moving_in_flight; 642 643 struct workqueue_struct *moving_gc_wq; 644 645 struct btree *root; 646 647 #ifdef CONFIG_BCACHE_DEBUG 648 struct btree *verify_data; 649 struct bset *verify_ondisk; 650 struct mutex verify_lock; 651 #endif 652 653 unsigned int nr_uuids; 654 struct uuid_entry *uuids; 655 BKEY_PADDED(uuid_bucket); 656 struct closure uuid_write; 657 struct semaphore uuid_write_mutex; 658 659 /* 660 * A btree node on disk could have too many bsets for an iterator to fit 661 * on the stack - have to dynamically allocate them 662 */ 663 mempool_t fill_iter; 664 665 struct bset_sort_state sort; 666 667 /* List of buckets we're currently writing data to */ 668 struct list_head data_buckets; 669 spinlock_t data_bucket_lock; 670 671 struct journal journal; 672 673 #define CONGESTED_MAX 1024 674 unsigned int congested_last_us; 675 atomic_t congested; 676 677 /* The rest of this all shows up in sysfs */ 678 unsigned int congested_read_threshold_us; 679 unsigned int congested_write_threshold_us; 680 681 struct time_stats btree_gc_time; 682 struct time_stats btree_split_time; 683 struct time_stats btree_read_time; 684 685 atomic_long_t cache_read_races; 686 atomic_long_t writeback_keys_done; 687 atomic_long_t writeback_keys_failed; 688 689 atomic_long_t reclaim; 690 atomic_long_t flush_write; 691 atomic_long_t retry_flush_write; 692 693 enum { 694 ON_ERROR_UNREGISTER, 695 ON_ERROR_PANIC, 696 } on_error; 697 #define DEFAULT_IO_ERROR_LIMIT 8 698 unsigned int error_limit; 699 unsigned int error_decay; 700 701 unsigned short journal_delay_ms; 702 bool expensive_debug_checks; 703 unsigned int verify:1; 704 unsigned int key_merging_disabled:1; 705 unsigned int gc_always_rewrite:1; 706 unsigned int shrinker_disabled:1; 707 unsigned int copy_gc_enabled:1; 708 709 #define BUCKET_HASH_BITS 12 710 struct hlist_head bucket_hash[1 << BUCKET_HASH_BITS]; 711 712 DECLARE_HEAP(struct btree *, flush_btree); 713 }; 714 715 struct bbio { 716 unsigned int submit_time_us; 717 union { 718 struct bkey key; 719 uint64_t _pad[3]; 720 /* 721 * We only need pad = 3 here because we only ever carry around a 722 * single pointer - i.e. the pointer we're doing io to/from. 723 */ 724 }; 725 struct bio bio; 726 }; 727 728 #define BTREE_PRIO USHRT_MAX 729 #define INITIAL_PRIO 32768U 730 731 #define btree_bytes(c) ((c)->btree_pages * PAGE_SIZE) 732 #define btree_blocks(b) \ 733 ((unsigned int) (KEY_SIZE(&b->key) >> (b)->c->block_bits)) 734 735 #define btree_default_blocks(c) \ 736 ((unsigned int) ((PAGE_SECTORS * (c)->btree_pages) >> (c)->block_bits)) 737 738 #define bucket_pages(c) ((c)->sb.bucket_size / PAGE_SECTORS) 739 #define bucket_bytes(c) ((c)->sb.bucket_size << 9) 740 #define block_bytes(c) ((c)->sb.block_size << 9) 741 742 #define prios_per_bucket(c) \ 743 ((bucket_bytes(c) - sizeof(struct prio_set)) / \ 744 sizeof(struct bucket_disk)) 745 #define prio_buckets(c) \ 746 DIV_ROUND_UP((size_t) (c)->sb.nbuckets, prios_per_bucket(c)) 747 748 static inline size_t sector_to_bucket(struct cache_set *c, sector_t s) 749 { 750 return s >> c->bucket_bits; 751 } 752 753 static inline sector_t bucket_to_sector(struct cache_set *c, size_t b) 754 { 755 return ((sector_t) b) << c->bucket_bits; 756 } 757 758 static inline sector_t bucket_remainder(struct cache_set *c, sector_t s) 759 { 760 return s & (c->sb.bucket_size - 1); 761 } 762 763 static inline struct cache *PTR_CACHE(struct cache_set *c, 764 const struct bkey *k, 765 unsigned int ptr) 766 { 767 return c->cache[PTR_DEV(k, ptr)]; 768 } 769 770 static inline size_t PTR_BUCKET_NR(struct cache_set *c, 771 const struct bkey *k, 772 unsigned int ptr) 773 { 774 return sector_to_bucket(c, PTR_OFFSET(k, ptr)); 775 } 776 777 static inline struct bucket *PTR_BUCKET(struct cache_set *c, 778 const struct bkey *k, 779 unsigned int ptr) 780 { 781 return PTR_CACHE(c, k, ptr)->buckets + PTR_BUCKET_NR(c, k, ptr); 782 } 783 784 static inline uint8_t gen_after(uint8_t a, uint8_t b) 785 { 786 uint8_t r = a - b; 787 788 return r > 128U ? 0 : r; 789 } 790 791 static inline uint8_t ptr_stale(struct cache_set *c, const struct bkey *k, 792 unsigned int i) 793 { 794 return gen_after(PTR_BUCKET(c, k, i)->gen, PTR_GEN(k, i)); 795 } 796 797 static inline bool ptr_available(struct cache_set *c, const struct bkey *k, 798 unsigned int i) 799 { 800 return (PTR_DEV(k, i) < MAX_CACHES_PER_SET) && PTR_CACHE(c, k, i); 801 } 802 803 /* Btree key macros */ 804 805 /* 806 * This is used for various on disk data structures - cache_sb, prio_set, bset, 807 * jset: The checksum is _always_ the first 8 bytes of these structs 808 */ 809 #define csum_set(i) \ 810 bch_crc64(((void *) (i)) + sizeof(uint64_t), \ 811 ((void *) bset_bkey_last(i)) - \ 812 (((void *) (i)) + sizeof(uint64_t))) 813 814 /* Error handling macros */ 815 816 #define btree_bug(b, ...) \ 817 do { \ 818 if (bch_cache_set_error((b)->c, __VA_ARGS__)) \ 819 dump_stack(); \ 820 } while (0) 821 822 #define cache_bug(c, ...) \ 823 do { \ 824 if (bch_cache_set_error(c, __VA_ARGS__)) \ 825 dump_stack(); \ 826 } while (0) 827 828 #define btree_bug_on(cond, b, ...) \ 829 do { \ 830 if (cond) \ 831 btree_bug(b, __VA_ARGS__); \ 832 } while (0) 833 834 #define cache_bug_on(cond, c, ...) \ 835 do { \ 836 if (cond) \ 837 cache_bug(c, __VA_ARGS__); \ 838 } while (0) 839 840 #define cache_set_err_on(cond, c, ...) \ 841 do { \ 842 if (cond) \ 843 bch_cache_set_error(c, __VA_ARGS__); \ 844 } while (0) 845 846 /* Looping macros */ 847 848 #define for_each_cache(ca, cs, iter) \ 849 for (iter = 0; ca = cs->cache[iter], iter < (cs)->sb.nr_in_set; iter++) 850 851 #define for_each_bucket(b, ca) \ 852 for (b = (ca)->buckets + (ca)->sb.first_bucket; \ 853 b < (ca)->buckets + (ca)->sb.nbuckets; b++) 854 855 static inline void cached_dev_put(struct cached_dev *dc) 856 { 857 if (refcount_dec_and_test(&dc->count)) 858 schedule_work(&dc->detach); 859 } 860 861 static inline bool cached_dev_get(struct cached_dev *dc) 862 { 863 if (!refcount_inc_not_zero(&dc->count)) 864 return false; 865 866 /* Paired with the mb in cached_dev_attach */ 867 smp_mb__after_atomic(); 868 return true; 869 } 870 871 /* 872 * bucket_gc_gen() returns the difference between the bucket's current gen and 873 * the oldest gen of any pointer into that bucket in the btree (last_gc). 874 */ 875 876 static inline uint8_t bucket_gc_gen(struct bucket *b) 877 { 878 return b->gen - b->last_gc; 879 } 880 881 #define BUCKET_GC_GEN_MAX 96U 882 883 #define kobj_attribute_write(n, fn) \ 884 static struct kobj_attribute ksysfs_##n = __ATTR(n, 0200, NULL, fn) 885 886 #define kobj_attribute_rw(n, show, store) \ 887 static struct kobj_attribute ksysfs_##n = \ 888 __ATTR(n, 0600, show, store) 889 890 static inline void wake_up_allocators(struct cache_set *c) 891 { 892 struct cache *ca; 893 unsigned int i; 894 895 for_each_cache(ca, c, i) 896 wake_up_process(ca->alloc_thread); 897 } 898 899 static inline void closure_bio_submit(struct cache_set *c, 900 struct bio *bio, 901 struct closure *cl) 902 { 903 closure_get(cl); 904 if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &c->flags))) { 905 bio->bi_status = BLK_STS_IOERR; 906 bio_endio(bio); 907 return; 908 } 909 generic_make_request(bio); 910 } 911 912 /* 913 * Prevent the kthread exits directly, and make sure when kthread_stop() 914 * is called to stop a kthread, it is still alive. If a kthread might be 915 * stopped by CACHE_SET_IO_DISABLE bit set, wait_for_kthread_stop() is 916 * necessary before the kthread returns. 917 */ 918 static inline void wait_for_kthread_stop(void) 919 { 920 while (!kthread_should_stop()) { 921 set_current_state(TASK_INTERRUPTIBLE); 922 schedule(); 923 } 924 } 925 926 /* Forward declarations */ 927 928 void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio); 929 void bch_count_io_errors(struct cache *ca, blk_status_t error, 930 int is_read, const char *m); 931 void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio, 932 blk_status_t error, const char *m); 933 void bch_bbio_endio(struct cache_set *c, struct bio *bio, 934 blk_status_t error, const char *m); 935 void bch_bbio_free(struct bio *bio, struct cache_set *c); 936 struct bio *bch_bbio_alloc(struct cache_set *c); 937 938 void __bch_submit_bbio(struct bio *bio, struct cache_set *c); 939 void bch_submit_bbio(struct bio *bio, struct cache_set *c, 940 struct bkey *k, unsigned int ptr); 941 942 uint8_t bch_inc_gen(struct cache *ca, struct bucket *b); 943 void bch_rescale_priorities(struct cache_set *c, int sectors); 944 945 bool bch_can_invalidate_bucket(struct cache *ca, struct bucket *b); 946 void __bch_invalidate_one_bucket(struct cache *ca, struct bucket *b); 947 948 void __bch_bucket_free(struct cache *ca, struct bucket *b); 949 void bch_bucket_free(struct cache_set *c, struct bkey *k); 950 951 long bch_bucket_alloc(struct cache *ca, unsigned int reserve, bool wait); 952 int __bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve, 953 struct bkey *k, int n, bool wait); 954 int bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve, 955 struct bkey *k, int n, bool wait); 956 bool bch_alloc_sectors(struct cache_set *c, struct bkey *k, 957 unsigned int sectors, unsigned int write_point, 958 unsigned int write_prio, bool wait); 959 bool bch_cached_dev_error(struct cached_dev *dc); 960 961 __printf(2, 3) 962 bool bch_cache_set_error(struct cache_set *c, const char *fmt, ...); 963 964 void bch_prio_write(struct cache *ca); 965 void bch_write_bdev_super(struct cached_dev *dc, struct closure *parent); 966 967 extern struct workqueue_struct *bcache_wq; 968 extern struct workqueue_struct *bch_journal_wq; 969 extern struct mutex bch_register_lock; 970 extern struct list_head bch_cache_sets; 971 972 extern struct kobj_type bch_cached_dev_ktype; 973 extern struct kobj_type bch_flash_dev_ktype; 974 extern struct kobj_type bch_cache_set_ktype; 975 extern struct kobj_type bch_cache_set_internal_ktype; 976 extern struct kobj_type bch_cache_ktype; 977 978 void bch_cached_dev_release(struct kobject *kobj); 979 void bch_flash_dev_release(struct kobject *kobj); 980 void bch_cache_set_release(struct kobject *kobj); 981 void bch_cache_release(struct kobject *kobj); 982 983 int bch_uuid_write(struct cache_set *c); 984 void bcache_write_super(struct cache_set *c); 985 986 int bch_flash_dev_create(struct cache_set *c, uint64_t size); 987 988 int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c, 989 uint8_t *set_uuid); 990 void bch_cached_dev_detach(struct cached_dev *dc); 991 void bch_cached_dev_run(struct cached_dev *dc); 992 void bcache_device_stop(struct bcache_device *d); 993 994 void bch_cache_set_unregister(struct cache_set *c); 995 void bch_cache_set_stop(struct cache_set *c); 996 997 struct cache_set *bch_cache_set_alloc(struct cache_sb *sb); 998 void bch_btree_cache_free(struct cache_set *c); 999 int bch_btree_cache_alloc(struct cache_set *c); 1000 void bch_moving_init_cache_set(struct cache_set *c); 1001 int bch_open_buckets_alloc(struct cache_set *c); 1002 void bch_open_buckets_free(struct cache_set *c); 1003 1004 int bch_cache_allocator_start(struct cache *ca); 1005 1006 void bch_debug_exit(void); 1007 void bch_debug_init(void); 1008 void bch_request_exit(void); 1009 int bch_request_init(void); 1010 1011 #endif /* _BCACHE_H */ 1012