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 spinlock_t btree_cannibalize_lock; 586 587 /* 588 * When we free a btree node, we increment the gen of the bucket the 589 * node is in - but we can't rewrite the prios and gens until we 590 * finished whatever it is we were doing, otherwise after a crash the 591 * btree node would be freed but for say a split, we might not have the 592 * pointers to the new nodes inserted into the btree yet. 593 * 594 * This is a refcount that blocks prio_write() until the new keys are 595 * written. 596 */ 597 atomic_t prio_blocked; 598 wait_queue_head_t bucket_wait; 599 600 /* 601 * For any bio we don't skip we subtract the number of sectors from 602 * rescale; when it hits 0 we rescale all the bucket priorities. 603 */ 604 atomic_t rescale; 605 /* 606 * used for GC, identify if any front side I/Os is inflight 607 */ 608 atomic_t search_inflight; 609 /* 610 * When we invalidate buckets, we use both the priority and the amount 611 * of good data to determine which buckets to reuse first - to weight 612 * those together consistently we keep track of the smallest nonzero 613 * priority of any bucket. 614 */ 615 uint16_t min_prio; 616 617 /* 618 * max(gen - last_gc) for all buckets. When it gets too big we have to 619 * gc to keep gens from wrapping around. 620 */ 621 uint8_t need_gc; 622 struct gc_stat gc_stats; 623 size_t nbuckets; 624 size_t avail_nbuckets; 625 626 struct task_struct *gc_thread; 627 /* Where in the btree gc currently is */ 628 struct bkey gc_done; 629 630 /* 631 * For automatical garbage collection after writeback completed, this 632 * varialbe is used as bit fields, 633 * - 0000 0001b (BCH_ENABLE_AUTO_GC): enable gc after writeback 634 * - 0000 0010b (BCH_DO_AUTO_GC): do gc after writeback 635 * This is an optimization for following write request after writeback 636 * finished, but read hit rate dropped due to clean data on cache is 637 * discarded. Unless user explicitly sets it via sysfs, it won't be 638 * enabled. 639 */ 640 #define BCH_ENABLE_AUTO_GC 1 641 #define BCH_DO_AUTO_GC 2 642 uint8_t gc_after_writeback; 643 644 /* 645 * The allocation code needs gc_mark in struct bucket to be correct, but 646 * it's not while a gc is in progress. Protected by bucket_lock. 647 */ 648 int gc_mark_valid; 649 650 /* Counts how many sectors bio_insert has added to the cache */ 651 atomic_t sectors_to_gc; 652 wait_queue_head_t gc_wait; 653 654 struct keybuf moving_gc_keys; 655 /* Number of moving GC bios in flight */ 656 struct semaphore moving_in_flight; 657 658 struct workqueue_struct *moving_gc_wq; 659 660 struct btree *root; 661 662 #ifdef CONFIG_BCACHE_DEBUG 663 struct btree *verify_data; 664 struct bset *verify_ondisk; 665 struct mutex verify_lock; 666 #endif 667 668 unsigned int nr_uuids; 669 struct uuid_entry *uuids; 670 BKEY_PADDED(uuid_bucket); 671 struct closure uuid_write; 672 struct semaphore uuid_write_mutex; 673 674 /* 675 * A btree node on disk could have too many bsets for an iterator to fit 676 * on the stack - have to dynamically allocate them. 677 * bch_cache_set_alloc() will make sure the pool can allocate iterators 678 * equipped with enough room that can host 679 * (sb.bucket_size / sb.block_size) 680 * btree_iter_sets, which is more than static MAX_BSETS. 681 */ 682 mempool_t fill_iter; 683 684 struct bset_sort_state sort; 685 686 /* List of buckets we're currently writing data to */ 687 struct list_head data_buckets; 688 spinlock_t data_bucket_lock; 689 690 struct journal journal; 691 692 #define CONGESTED_MAX 1024 693 unsigned int congested_last_us; 694 atomic_t congested; 695 696 /* The rest of this all shows up in sysfs */ 697 unsigned int congested_read_threshold_us; 698 unsigned int congested_write_threshold_us; 699 700 struct time_stats btree_gc_time; 701 struct time_stats btree_split_time; 702 struct time_stats btree_read_time; 703 704 atomic_long_t cache_read_races; 705 atomic_long_t writeback_keys_done; 706 atomic_long_t writeback_keys_failed; 707 708 atomic_long_t reclaim; 709 atomic_long_t reclaimed_journal_buckets; 710 atomic_long_t flush_write; 711 712 enum { 713 ON_ERROR_UNREGISTER, 714 ON_ERROR_PANIC, 715 } on_error; 716 #define DEFAULT_IO_ERROR_LIMIT 8 717 unsigned int error_limit; 718 unsigned int error_decay; 719 720 unsigned short journal_delay_ms; 721 bool expensive_debug_checks; 722 unsigned int verify:1; 723 unsigned int key_merging_disabled:1; 724 unsigned int gc_always_rewrite:1; 725 unsigned int shrinker_disabled:1; 726 unsigned int copy_gc_enabled:1; 727 unsigned int idle_max_writeback_rate_enabled:1; 728 729 #define BUCKET_HASH_BITS 12 730 struct hlist_head bucket_hash[1 << BUCKET_HASH_BITS]; 731 }; 732 733 struct bbio { 734 unsigned int submit_time_us; 735 union { 736 struct bkey key; 737 uint64_t _pad[3]; 738 /* 739 * We only need pad = 3 here because we only ever carry around a 740 * single pointer - i.e. the pointer we're doing io to/from. 741 */ 742 }; 743 struct bio bio; 744 }; 745 746 #define BTREE_PRIO USHRT_MAX 747 #define INITIAL_PRIO 32768U 748 749 #define btree_bytes(c) ((c)->btree_pages * PAGE_SIZE) 750 #define btree_blocks(b) \ 751 ((unsigned int) (KEY_SIZE(&b->key) >> (b)->c->block_bits)) 752 753 #define btree_default_blocks(c) \ 754 ((unsigned int) ((PAGE_SECTORS * (c)->btree_pages) >> (c)->block_bits)) 755 756 #define bucket_pages(c) ((c)->sb.bucket_size / PAGE_SECTORS) 757 #define bucket_bytes(c) ((c)->sb.bucket_size << 9) 758 #define block_bytes(c) ((c)->sb.block_size << 9) 759 760 #define prios_per_bucket(c) \ 761 ((bucket_bytes(c) - sizeof(struct prio_set)) / \ 762 sizeof(struct bucket_disk)) 763 #define prio_buckets(c) \ 764 DIV_ROUND_UP((size_t) (c)->sb.nbuckets, prios_per_bucket(c)) 765 766 static inline size_t sector_to_bucket(struct cache_set *c, sector_t s) 767 { 768 return s >> c->bucket_bits; 769 } 770 771 static inline sector_t bucket_to_sector(struct cache_set *c, size_t b) 772 { 773 return ((sector_t) b) << c->bucket_bits; 774 } 775 776 static inline sector_t bucket_remainder(struct cache_set *c, sector_t s) 777 { 778 return s & (c->sb.bucket_size - 1); 779 } 780 781 static inline struct cache *PTR_CACHE(struct cache_set *c, 782 const struct bkey *k, 783 unsigned int ptr) 784 { 785 return c->cache[PTR_DEV(k, ptr)]; 786 } 787 788 static inline size_t PTR_BUCKET_NR(struct cache_set *c, 789 const struct bkey *k, 790 unsigned int ptr) 791 { 792 return sector_to_bucket(c, PTR_OFFSET(k, ptr)); 793 } 794 795 static inline struct bucket *PTR_BUCKET(struct cache_set *c, 796 const struct bkey *k, 797 unsigned int ptr) 798 { 799 return PTR_CACHE(c, k, ptr)->buckets + PTR_BUCKET_NR(c, k, ptr); 800 } 801 802 static inline uint8_t gen_after(uint8_t a, uint8_t b) 803 { 804 uint8_t r = a - b; 805 806 return r > 128U ? 0 : r; 807 } 808 809 static inline uint8_t ptr_stale(struct cache_set *c, const struct bkey *k, 810 unsigned int i) 811 { 812 return gen_after(PTR_BUCKET(c, k, i)->gen, PTR_GEN(k, i)); 813 } 814 815 static inline bool ptr_available(struct cache_set *c, const struct bkey *k, 816 unsigned int i) 817 { 818 return (PTR_DEV(k, i) < MAX_CACHES_PER_SET) && PTR_CACHE(c, k, i); 819 } 820 821 /* Btree key macros */ 822 823 /* 824 * This is used for various on disk data structures - cache_sb, prio_set, bset, 825 * jset: The checksum is _always_ the first 8 bytes of these structs 826 */ 827 #define csum_set(i) \ 828 bch_crc64(((void *) (i)) + sizeof(uint64_t), \ 829 ((void *) bset_bkey_last(i)) - \ 830 (((void *) (i)) + sizeof(uint64_t))) 831 832 /* Error handling macros */ 833 834 #define btree_bug(b, ...) \ 835 do { \ 836 if (bch_cache_set_error((b)->c, __VA_ARGS__)) \ 837 dump_stack(); \ 838 } while (0) 839 840 #define cache_bug(c, ...) \ 841 do { \ 842 if (bch_cache_set_error(c, __VA_ARGS__)) \ 843 dump_stack(); \ 844 } while (0) 845 846 #define btree_bug_on(cond, b, ...) \ 847 do { \ 848 if (cond) \ 849 btree_bug(b, __VA_ARGS__); \ 850 } while (0) 851 852 #define cache_bug_on(cond, c, ...) \ 853 do { \ 854 if (cond) \ 855 cache_bug(c, __VA_ARGS__); \ 856 } while (0) 857 858 #define cache_set_err_on(cond, c, ...) \ 859 do { \ 860 if (cond) \ 861 bch_cache_set_error(c, __VA_ARGS__); \ 862 } while (0) 863 864 /* Looping macros */ 865 866 #define for_each_cache(ca, cs, iter) \ 867 for (iter = 0; ca = cs->cache[iter], iter < (cs)->sb.nr_in_set; iter++) 868 869 #define for_each_bucket(b, ca) \ 870 for (b = (ca)->buckets + (ca)->sb.first_bucket; \ 871 b < (ca)->buckets + (ca)->sb.nbuckets; b++) 872 873 static inline void cached_dev_put(struct cached_dev *dc) 874 { 875 if (refcount_dec_and_test(&dc->count)) 876 schedule_work(&dc->detach); 877 } 878 879 static inline bool cached_dev_get(struct cached_dev *dc) 880 { 881 if (!refcount_inc_not_zero(&dc->count)) 882 return false; 883 884 /* Paired with the mb in cached_dev_attach */ 885 smp_mb__after_atomic(); 886 return true; 887 } 888 889 /* 890 * bucket_gc_gen() returns the difference between the bucket's current gen and 891 * the oldest gen of any pointer into that bucket in the btree (last_gc). 892 */ 893 894 static inline uint8_t bucket_gc_gen(struct bucket *b) 895 { 896 return b->gen - b->last_gc; 897 } 898 899 #define BUCKET_GC_GEN_MAX 96U 900 901 #define kobj_attribute_write(n, fn) \ 902 static struct kobj_attribute ksysfs_##n = __ATTR(n, 0200, NULL, fn) 903 904 #define kobj_attribute_rw(n, show, store) \ 905 static struct kobj_attribute ksysfs_##n = \ 906 __ATTR(n, 0600, show, store) 907 908 static inline void wake_up_allocators(struct cache_set *c) 909 { 910 struct cache *ca; 911 unsigned int i; 912 913 for_each_cache(ca, c, i) 914 wake_up_process(ca->alloc_thread); 915 } 916 917 static inline void closure_bio_submit(struct cache_set *c, 918 struct bio *bio, 919 struct closure *cl) 920 { 921 closure_get(cl); 922 if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &c->flags))) { 923 bio->bi_status = BLK_STS_IOERR; 924 bio_endio(bio); 925 return; 926 } 927 generic_make_request(bio); 928 } 929 930 /* 931 * Prevent the kthread exits directly, and make sure when kthread_stop() 932 * is called to stop a kthread, it is still alive. If a kthread might be 933 * stopped by CACHE_SET_IO_DISABLE bit set, wait_for_kthread_stop() is 934 * necessary before the kthread returns. 935 */ 936 static inline void wait_for_kthread_stop(void) 937 { 938 while (!kthread_should_stop()) { 939 set_current_state(TASK_INTERRUPTIBLE); 940 schedule(); 941 } 942 } 943 944 /* Forward declarations */ 945 946 void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio); 947 void bch_count_io_errors(struct cache *ca, blk_status_t error, 948 int is_read, const char *m); 949 void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio, 950 blk_status_t error, const char *m); 951 void bch_bbio_endio(struct cache_set *c, struct bio *bio, 952 blk_status_t error, const char *m); 953 void bch_bbio_free(struct bio *bio, struct cache_set *c); 954 struct bio *bch_bbio_alloc(struct cache_set *c); 955 956 void __bch_submit_bbio(struct bio *bio, struct cache_set *c); 957 void bch_submit_bbio(struct bio *bio, struct cache_set *c, 958 struct bkey *k, unsigned int ptr); 959 960 uint8_t bch_inc_gen(struct cache *ca, struct bucket *b); 961 void bch_rescale_priorities(struct cache_set *c, int sectors); 962 963 bool bch_can_invalidate_bucket(struct cache *ca, struct bucket *b); 964 void __bch_invalidate_one_bucket(struct cache *ca, struct bucket *b); 965 966 void __bch_bucket_free(struct cache *ca, struct bucket *b); 967 void bch_bucket_free(struct cache_set *c, struct bkey *k); 968 969 long bch_bucket_alloc(struct cache *ca, unsigned int reserve, bool wait); 970 int __bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve, 971 struct bkey *k, int n, bool wait); 972 int bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve, 973 struct bkey *k, int n, bool wait); 974 bool bch_alloc_sectors(struct cache_set *c, struct bkey *k, 975 unsigned int sectors, unsigned int write_point, 976 unsigned int write_prio, bool wait); 977 bool bch_cached_dev_error(struct cached_dev *dc); 978 979 __printf(2, 3) 980 bool bch_cache_set_error(struct cache_set *c, const char *fmt, ...); 981 982 int bch_prio_write(struct cache *ca, bool wait); 983 void bch_write_bdev_super(struct cached_dev *dc, struct closure *parent); 984 985 extern struct workqueue_struct *bcache_wq; 986 extern struct workqueue_struct *bch_journal_wq; 987 extern struct mutex bch_register_lock; 988 extern struct list_head bch_cache_sets; 989 990 extern struct kobj_type bch_cached_dev_ktype; 991 extern struct kobj_type bch_flash_dev_ktype; 992 extern struct kobj_type bch_cache_set_ktype; 993 extern struct kobj_type bch_cache_set_internal_ktype; 994 extern struct kobj_type bch_cache_ktype; 995 996 void bch_cached_dev_release(struct kobject *kobj); 997 void bch_flash_dev_release(struct kobject *kobj); 998 void bch_cache_set_release(struct kobject *kobj); 999 void bch_cache_release(struct kobject *kobj); 1000 1001 int bch_uuid_write(struct cache_set *c); 1002 void bcache_write_super(struct cache_set *c); 1003 1004 int bch_flash_dev_create(struct cache_set *c, uint64_t size); 1005 1006 int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c, 1007 uint8_t *set_uuid); 1008 void bch_cached_dev_detach(struct cached_dev *dc); 1009 int bch_cached_dev_run(struct cached_dev *dc); 1010 void bcache_device_stop(struct bcache_device *d); 1011 1012 void bch_cache_set_unregister(struct cache_set *c); 1013 void bch_cache_set_stop(struct cache_set *c); 1014 1015 struct cache_set *bch_cache_set_alloc(struct cache_sb *sb); 1016 void bch_btree_cache_free(struct cache_set *c); 1017 int bch_btree_cache_alloc(struct cache_set *c); 1018 void bch_moving_init_cache_set(struct cache_set *c); 1019 int bch_open_buckets_alloc(struct cache_set *c); 1020 void bch_open_buckets_free(struct cache_set *c); 1021 1022 int bch_cache_allocator_start(struct cache *ca); 1023 1024 void bch_debug_exit(void); 1025 void bch_debug_init(void); 1026 void bch_request_exit(void); 1027 int bch_request_init(void); 1028 1029 #endif /* _BCACHE_H */ 1030