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1/* SPDX-License-Identifier: GPL-2.0 */2#ifndef _BCACHE_H3#define _BCACHE_H4 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, but11 * it's about 95% plumbed through. A cache set and its cache devices is sort of12 * like a md raid array and its component devices. Most of the code doesn't care13 * 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 dirty16 * cached data and metadata, without mirroring clean cached data.17 *18 * Backing devices are different, in that they have a lifetime independent of a19 * cache set. When you register a newly formatted backing device it'll come up20 * in passthrough mode, and then you can attach and detach a backing device from21 * a cache set at runtime - while it's mounted and in use. Detaching implicitly22 * 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 distinction27 * between struct cached_dev and struct bcache_device. A flash only volume28 * works much like a bcache device that has a backing device, except the29 * "cached" data is always dirty. The end result is that we get thin30 * provisioning with very little additional code.31 *32 * Flash only volumes work but they're not production ready because the moving33 * 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 normal38 * operation all of our available space will be allocated. Thus, we need an39 * efficient way of deleting things from the cache so we can write new things to40 * it.41 *42 * To do this, we first divide the cache device up into buckets. A bucket is the43 * 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 with47 * it. The gens and priorities for all the buckets are stored contiguously and48 * packed on disk (in a linked list of buckets - aside from the superblock, all49 * of bcache's metadata is stored in buckets).50 *51 * The priority is used to implement an LRU. We reset a bucket's priority when52 * we allocate it or on cache it, and every so often we decrement the priority53 * 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 857 * bit generation embedded in it; for a pointer to be considered valid, its gen58 * must match the gen of the bucket it points into. Thus, to reuse a bucket all59 * we have to do is increment its gen (and write its new gen to disk; we batch60 * this up).61 *62 * Bcache is entirely COW - we never write twice to a bucket, even buckets that63 * 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 variable72 * number of pointers attached to them (potentially zero, which is handy for73 * invalidating the cache).74 *75 * The key itself is an inode:offset pair. The inode number corresponds to a76 * backing device or a flash only volume. The offset is the ending offset of the77 * extent within the inode - not the starting offset; this makes lookups78 * slightly more convenient.79 *80 * Pointers contain the cache device id, the offset on that device, and an 8 bit81 * generation number. More on the gen later.82 *83 * Index lookups are not fully abstracted - cache lookups in particular are84 * still somewhat mixed in with the btree code, but things are headed in that85 * direction.86 *87 * Updates are fairly well abstracted, though. There are two different ways of88 * 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 is92 * used to update the index after a write.93 *94 * BTREE_REPLACE is really cmpxchg(); it inserts a key into the btree iff it is95 * overwriting a key that matches another given key. This is used for inserting96 * data into the cache after a cache miss, and for background writeback, and for97 * the moving garbage collector.98 *99 * There is no "delete" operation; deleting things from the index is100 * accomplished by either by invalidating pointers (by incrementing a bucket's101 * gen) or by inserting a key with 0 pointers - which will overwrite anything102 * previously present at that location in the index.103 *104 * This means that there are always stale/invalid keys in the btree. They're105 * filtered out by the code that iterates through a btree node, and removed when106 * a btree node is rewritten.107 *108 * BTREE NODES:109 *110 * Our unit of allocation is a bucket, and we can't arbitrarily allocate and111 * 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 node114 * - no less than 1/4th - but a bucket still contains no more than a single115 * btree node. I'd actually like to change this, but for now we rely on the116 * 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 textbook119 * btree implementation.120 *121 * The way this is solved is that btree nodes are internally log structured; we122 * can append new keys to an existing btree node without rewriting it. This123 * 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 would126 * be expensive, and we have to distinguish between the keys we have written and127 * the keys we haven't. So to do a lookup in a btree node, we have to search128 * each sorted set. But we do merge written sets together lazily, so the cost of129 * these extra searches is quite low (normally most of the keys in a btree node130 * will be in one big set, and then there'll be one or two sets that are much131 * smaller).132 *133 * This log structure makes bcache's btree more of a hybrid between a134 * conventional btree and a compacting data structure, with some of the135 * advantages of both.136 *137 * GARBAGE COLLECTION:138 *139 * We can't just invalidate any bucket - it might contain dirty data or140 * metadata. If it once contained dirty data, other writes might overwrite it141 * 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 that145 * allocation can reuse buckets sooner when they've been mostly overwritten.146 *147 * It also does some things that are really internal to the btree148 * implementation. If a btree node contains pointers that are stale by more than149 * some threshold, it rewrites the btree node to avoid the bucket's generation150 * 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 strictly155 * order metadata writes so that the btree and everything else is consistent on156 * disk in the event of an unclean shutdown, and in fact bcache had writeback157 * caching (with recovery from unclean shutdown) before journalling was158 * implemented.159 *160 * Rather, the journal is purely a performance optimization; we can't complete a161 * write until we've updated the index on disk, otherwise the cache would be162 * inconsistent in the event of an unclean shutdown. This means that without the163 * journal, on random write workloads we constantly have to update all the leaf164 * nodes in the btree, and those writes will be mostly empty (appending at most165 * 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 reinsert169 * all the keys in the open journal entries. That means that when we're updating170 * a node in the btree, we can wait until a 4k block of keys fills up before171 * writing them out.172 *173 * For simplicity, we only journal updates to leaf nodes; updates to parent174 * nodes are rare enough (since our leaf nodes are huge) that it wasn't worth175 * the complexity to deal with journalling them (in particular, journal replay)176 * - updates to non leaf nodes just happen synchronously (see btree_split()).177 */178 179#define pr_fmt(fmt) "bcache: %s() " fmt, __func__180 181#include <linux/bio.h>182#include <linux/closure.h>183#include <linux/kobject.h>184#include <linux/list.h>185#include <linux/mutex.h>186#include <linux/rbtree.h>187#include <linux/rwsem.h>188#include <linux/refcount.h>189#include <linux/types.h>190#include <linux/workqueue.h>191#include <linux/kthread.h>192 193#include "bcache_ondisk.h"194#include "bset.h"195#include "util.h"196 197struct bucket {198 atomic_t pin;199 uint16_t prio;200 uint8_t gen;201 uint8_t last_gc; /* Most out of date gen in the btree */202 uint16_t gc_mark; /* Bitfield used by GC. See below for field */203 uint16_t reclaimable_in_gc:1;204};205 206/*207 * I'd use bitfields for these, but I don't trust the compiler not to screw me208 * as multiple threads touch struct bucket without locking209 */210 211BITMASK(GC_MARK, struct bucket, gc_mark, 0, 2);212#define GC_MARK_RECLAIMABLE 1213#define GC_MARK_DIRTY 2214#define GC_MARK_METADATA 3215#define GC_SECTORS_USED_SIZE 13216#define MAX_GC_SECTORS_USED (~(~0ULL << GC_SECTORS_USED_SIZE))217BITMASK(GC_SECTORS_USED, struct bucket, gc_mark, 2, GC_SECTORS_USED_SIZE);218BITMASK(GC_MOVE, struct bucket, gc_mark, 15, 1);219 220#include "journal.h"221#include "stats.h"222struct search;223struct btree;224struct keybuf;225 226struct keybuf_key {227 struct rb_node node;228 BKEY_PADDED(key);229 void *private;230};231 232struct keybuf {233 struct bkey last_scanned;234 spinlock_t lock;235 236 /*237 * Beginning and end of range in rb tree - so that we can skip taking238 * lock and checking the rb tree when we need to check for overlapping239 * keys.240 */241 struct bkey start;242 struct bkey end;243 244 struct rb_root keys;245 246#define KEYBUF_NR 500247 DECLARE_ARRAY_ALLOCATOR(struct keybuf_key, freelist, KEYBUF_NR);248};249 250struct bcache_device {251 struct closure cl;252 253 struct kobject kobj;254 255 struct cache_set *c;256 unsigned int id;257#define BCACHEDEVNAME_SIZE 12258 char name[BCACHEDEVNAME_SIZE];259 260 struct gendisk *disk;261 262 unsigned long flags;263#define BCACHE_DEV_CLOSING 0264#define BCACHE_DEV_DETACHING 1265#define BCACHE_DEV_UNLINK_DONE 2266#define BCACHE_DEV_WB_RUNNING 3267#define BCACHE_DEV_RATE_DW_RUNNING 4268 int nr_stripes;269#define BCH_MIN_STRIPE_SZ ((4 << 20) >> SECTOR_SHIFT)270 unsigned int stripe_size;271 atomic_t *stripe_sectors_dirty;272 unsigned long *full_dirty_stripes;273 274 struct bio_set bio_split;275 276 unsigned int data_csum:1;277 278 int (*cache_miss)(struct btree *b, struct search *s,279 struct bio *bio, unsigned int sectors);280 int (*ioctl)(struct bcache_device *d, blk_mode_t mode,281 unsigned int cmd, unsigned long arg);282};283 284struct io {285 /* Used to track sequential IO so it can be skipped */286 struct hlist_node hash;287 struct list_head lru;288 289 unsigned long jiffies;290 unsigned int sequential;291 sector_t last;292};293 294enum stop_on_failure {295 BCH_CACHED_DEV_STOP_AUTO = 0,296 BCH_CACHED_DEV_STOP_ALWAYS,297 BCH_CACHED_DEV_STOP_MODE_MAX,298};299 300struct cached_dev {301 struct list_head list;302 struct bcache_device disk;303 struct block_device *bdev;304 struct file *bdev_file;305 306 struct cache_sb sb;307 struct cache_sb_disk *sb_disk;308 struct bio sb_bio;309 struct bio_vec sb_bv[1];310 struct closure sb_write;311 struct semaphore sb_write_mutex;312 313 /* Refcount on the cache set. Always nonzero when we're caching. */314 refcount_t count;315 struct work_struct detach;316 317 /*318 * Device might not be running if it's dirty and the cache set hasn't319 * showed up yet.320 */321 atomic_t running;322 323 /*324 * Writes take a shared lock from start to finish; scanning for dirty325 * data to refill the rb tree requires an exclusive lock.326 */327 struct rw_semaphore writeback_lock;328 329 /*330 * Nonzero, and writeback has a refcount (d->count), iff there is dirty331 * data in the cache. Protected by writeback_lock; must have an332 * shared lock to set and exclusive lock to clear.333 */334 atomic_t has_dirty;335 336#define BCH_CACHE_READA_ALL 0337#define BCH_CACHE_READA_META_ONLY 1338 unsigned int cache_readahead_policy;339 struct bch_ratelimit writeback_rate;340 struct delayed_work writeback_rate_update;341 342 /* Limit number of writeback bios in flight */343 struct semaphore in_flight;344 struct task_struct *writeback_thread;345 struct workqueue_struct *writeback_write_wq;346 347 struct keybuf writeback_keys;348 349 struct task_struct *status_update_thread;350 /*351 * Order the write-half of writeback operations strongly in dispatch352 * order. (Maintain LBA order; don't allow reads completing out of353 * order to re-order the writes...)354 */355 struct closure_waitlist writeback_ordering_wait;356 atomic_t writeback_sequence_next;357 358 /* For tracking sequential IO */359#define RECENT_IO_BITS 7360#define RECENT_IO (1 << RECENT_IO_BITS)361 struct io io[RECENT_IO];362 struct hlist_head io_hash[RECENT_IO + 1];363 struct list_head io_lru;364 spinlock_t io_lock;365 366 struct cache_accounting accounting;367 368 /* The rest of this all shows up in sysfs */369 unsigned int sequential_cutoff;370 371 unsigned int io_disable:1;372 unsigned int verify:1;373 unsigned int bypass_torture_test:1;374 375 unsigned int partial_stripes_expensive:1;376 unsigned int writeback_metadata:1;377 unsigned int writeback_running:1;378 unsigned int writeback_consider_fragment:1;379 unsigned char writeback_percent;380 unsigned int writeback_delay;381 382 uint64_t writeback_rate_target;383 int64_t writeback_rate_proportional;384 int64_t writeback_rate_integral;385 int64_t writeback_rate_integral_scaled;386 int32_t writeback_rate_change;387 388 unsigned int writeback_rate_update_seconds;389 unsigned int writeback_rate_i_term_inverse;390 unsigned int writeback_rate_p_term_inverse;391 unsigned int writeback_rate_fp_term_low;392 unsigned int writeback_rate_fp_term_mid;393 unsigned int writeback_rate_fp_term_high;394 unsigned int writeback_rate_minimum;395 396 enum stop_on_failure stop_when_cache_set_failed;397#define DEFAULT_CACHED_DEV_ERROR_LIMIT 64398 atomic_t io_errors;399 unsigned int error_limit;400 unsigned int offline_seconds;401 402 /*403 * Retry to update writeback_rate if contention happens for404 * down_read(dc->writeback_lock) in update_writeback_rate()405 */406#define BCH_WBRATE_UPDATE_MAX_SKIPS 15407 unsigned int rate_update_retry;408};409 410enum alloc_reserve {411 RESERVE_BTREE,412 RESERVE_PRIO,413 RESERVE_MOVINGGC,414 RESERVE_NONE,415 RESERVE_NR,416};417 418struct cache {419 struct cache_set *set;420 struct cache_sb sb;421 struct cache_sb_disk *sb_disk;422 struct bio sb_bio;423 struct bio_vec sb_bv[1];424 425 struct kobject kobj;426 struct block_device *bdev;427 struct file *bdev_file;428 429 struct task_struct *alloc_thread;430 431 struct closure prio;432 struct prio_set *disk_buckets;433 434 /*435 * When allocating new buckets, prio_write() gets first dibs - since we436 * may not be allocate at all without writing priorities and gens.437 * prio_last_buckets[] contains the last buckets we wrote priorities to438 * (so gc can mark them as metadata), prio_buckets[] contains the439 * buckets allocated for the next prio write.440 */441 uint64_t *prio_buckets;442 uint64_t *prio_last_buckets;443 444 /*445 * free: Buckets that are ready to be used446 *447 * free_inc: Incoming buckets - these are buckets that currently have448 * cached data in them, and we can't reuse them until after we write449 * their new gen to disk. After prio_write() finishes writing the new450 * gens/prios, they'll be moved to the free list (and possibly discarded451 * in the process)452 */453 DECLARE_FIFO(long, free)[RESERVE_NR];454 DECLARE_FIFO(long, free_inc);455 456 size_t fifo_last_bucket;457 458 /* Allocation stuff: */459 struct bucket *buckets;460 461 DEFINE_MIN_HEAP(struct bucket *, cache_heap) heap;462 463 /*464 * If nonzero, we know we aren't going to find any buckets to invalidate465 * until a gc finishes - otherwise we could pointlessly burn a ton of466 * cpu467 */468 unsigned int invalidate_needs_gc;469 470 bool discard; /* Get rid of? */471 472 struct journal_device journal;473 474 /* The rest of this all shows up in sysfs */475#define IO_ERROR_SHIFT 20476 atomic_t io_errors;477 atomic_t io_count;478 479 atomic_long_t meta_sectors_written;480 atomic_long_t btree_sectors_written;481 atomic_long_t sectors_written;482};483 484struct gc_stat {485 size_t nodes;486 size_t nodes_pre;487 size_t key_bytes;488 489 size_t nkeys;490 uint64_t data; /* sectors */491 unsigned int in_use; /* percent */492};493 494/*495 * Flag bits, for how the cache set is shutting down, and what phase it's at:496 *497 * CACHE_SET_UNREGISTERING means we're not just shutting down, we're detaching498 * all the backing devices first (their cached data gets invalidated, and they499 * won't automatically reattach).500 *501 * CACHE_SET_STOPPING always gets set first when we're closing down a cache set;502 * we'll continue to run normally for awhile with CACHE_SET_STOPPING set (i.e.503 * flushing dirty data).504 *505 * CACHE_SET_RUNNING means all cache devices have been registered and journal506 * replay is complete.507 *508 * CACHE_SET_IO_DISABLE is set when bcache is stopping the whold cache set, all509 * external and internal I/O should be denied when this flag is set.510 *511 */512#define CACHE_SET_UNREGISTERING 0513#define CACHE_SET_STOPPING 1514#define CACHE_SET_RUNNING 2515#define CACHE_SET_IO_DISABLE 3516 517struct cache_set {518 struct closure cl;519 520 struct list_head list;521 struct kobject kobj;522 struct kobject internal;523 struct dentry *debug;524 struct cache_accounting accounting;525 526 unsigned long flags;527 atomic_t idle_counter;528 atomic_t at_max_writeback_rate;529 530 struct cache *cache;531 532 struct bcache_device **devices;533 unsigned int devices_max_used;534 atomic_t attached_dev_nr;535 struct list_head cached_devs;536 uint64_t cached_dev_sectors;537 atomic_long_t flash_dev_dirty_sectors;538 struct closure caching;539 540 struct closure sb_write;541 struct semaphore sb_write_mutex;542 543 mempool_t search;544 mempool_t bio_meta;545 struct bio_set bio_split;546 547 /* For the btree cache */548 struct shrinker *shrink;549 550 /* For the btree cache and anything allocation related */551 struct mutex bucket_lock;552 553 /* log2(bucket_size), in sectors */554 unsigned short bucket_bits;555 556 /* log2(block_size), in sectors */557 unsigned short block_bits;558 559 /*560 * Default number of pages for a new btree node - may be less than a561 * full bucket562 */563 unsigned int btree_pages;564 565 /*566 * Lists of struct btrees; lru is the list for structs that have memory567 * allocated for actual btree node, freed is for structs that do not.568 *569 * We never free a struct btree, except on shutdown - we just put it on570 * the btree_cache_freed list and reuse it later. This simplifies the571 * code, and it doesn't cost us much memory as the memory usage is572 * dominated by buffers that hold the actual btree node data and those573 * can be freed - and the number of struct btrees allocated is574 * effectively bounded.575 *576 * btree_cache_freeable effectively is a small cache - we use it because577 * high order page allocations can be rather expensive, and it's quite578 * common to delete and allocate btree nodes in quick succession. It579 * should never grow past ~2-3 nodes in practice.580 */581 struct list_head btree_cache;582 struct list_head btree_cache_freeable;583 struct list_head btree_cache_freed;584 585 /* Number of elements in btree_cache + btree_cache_freeable lists */586 unsigned int btree_cache_used;587 588 /*589 * If we need to allocate memory for a new btree node and that590 * allocation fails, we can cannibalize another node in the btree cache591 * to satisfy the allocation - lock to guarantee only one thread does592 * this at a time:593 */594 wait_queue_head_t btree_cache_wait;595 struct task_struct *btree_cache_alloc_lock;596 spinlock_t btree_cannibalize_lock;597 598 /*599 * When we free a btree node, we increment the gen of the bucket the600 * node is in - but we can't rewrite the prios and gens until we601 * finished whatever it is we were doing, otherwise after a crash the602 * btree node would be freed but for say a split, we might not have the603 * pointers to the new nodes inserted into the btree yet.604 *605 * This is a refcount that blocks prio_write() until the new keys are606 * written.607 */608 atomic_t prio_blocked;609 wait_queue_head_t bucket_wait;610 611 /*612 * For any bio we don't skip we subtract the number of sectors from613 * rescale; when it hits 0 we rescale all the bucket priorities.614 */615 atomic_t rescale;616 /*617 * used for GC, identify if any front side I/Os is inflight618 */619 atomic_t search_inflight;620 /*621 * When we invalidate buckets, we use both the priority and the amount622 * of good data to determine which buckets to reuse first - to weight623 * those together consistently we keep track of the smallest nonzero624 * priority of any bucket.625 */626 uint16_t min_prio;627 628 /*629 * max(gen - last_gc) for all buckets. When it gets too big we have to630 * gc to keep gens from wrapping around.631 */632 uint8_t need_gc;633 struct gc_stat gc_stats;634 size_t nbuckets;635 size_t avail_nbuckets;636 637 struct task_struct *gc_thread;638 /* Where in the btree gc currently is */639 struct bkey gc_done;640 641 /*642 * For automatical garbage collection after writeback completed, this643 * varialbe is used as bit fields,644 * - 0000 0001b (BCH_ENABLE_AUTO_GC): enable gc after writeback645 * - 0000 0010b (BCH_DO_AUTO_GC): do gc after writeback646 * This is an optimization for following write request after writeback647 * finished, but read hit rate dropped due to clean data on cache is648 * discarded. Unless user explicitly sets it via sysfs, it won't be649 * enabled.650 */651#define BCH_ENABLE_AUTO_GC 1652#define BCH_DO_AUTO_GC 2653 uint8_t gc_after_writeback;654 655 /*656 * The allocation code needs gc_mark in struct bucket to be correct, but657 * it's not while a gc is in progress. Protected by bucket_lock.658 */659 int gc_mark_valid;660 661 /* Counts how many sectors bio_insert has added to the cache */662 atomic_t sectors_to_gc;663 wait_queue_head_t gc_wait;664 665 struct keybuf moving_gc_keys;666 /* Number of moving GC bios in flight */667 struct semaphore moving_in_flight;668 669 struct workqueue_struct *moving_gc_wq;670 671 struct btree *root;672 673#ifdef CONFIG_BCACHE_DEBUG674 struct btree *verify_data;675 struct bset *verify_ondisk;676 struct mutex verify_lock;677#endif678 679 uint8_t set_uuid[16];680 unsigned int nr_uuids;681 struct uuid_entry *uuids;682 BKEY_PADDED(uuid_bucket);683 struct closure uuid_write;684 struct semaphore uuid_write_mutex;685 686 /*687 * A btree node on disk could have too many bsets for an iterator to fit688 * on the stack - have to dynamically allocate them.689 * bch_cache_set_alloc() will make sure the pool can allocate iterators690 * equipped with enough room that can host691 * (sb.bucket_size / sb.block_size)692 * btree_iter_sets, which is more than static MAX_BSETS.693 */694 mempool_t fill_iter;695 696 struct bset_sort_state sort;697 698 /* List of buckets we're currently writing data to */699 struct list_head data_buckets;700 spinlock_t data_bucket_lock;701 702 struct journal journal;703 704#define CONGESTED_MAX 1024705 unsigned int congested_last_us;706 atomic_t congested;707 708 /* The rest of this all shows up in sysfs */709 unsigned int congested_read_threshold_us;710 unsigned int congested_write_threshold_us;711 712 struct time_stats btree_gc_time;713 struct time_stats btree_split_time;714 struct time_stats btree_read_time;715 716 atomic_long_t cache_read_races;717 atomic_long_t writeback_keys_done;718 atomic_long_t writeback_keys_failed;719 720 atomic_long_t reclaim;721 atomic_long_t reclaimed_journal_buckets;722 atomic_long_t flush_write;723 724 enum {725 ON_ERROR_UNREGISTER,726 ON_ERROR_PANIC,727 } on_error;728#define DEFAULT_IO_ERROR_LIMIT 8729 unsigned int error_limit;730 unsigned int error_decay;731 732 unsigned short journal_delay_ms;733 bool expensive_debug_checks;734 unsigned int verify:1;735 unsigned int key_merging_disabled:1;736 unsigned int gc_always_rewrite:1;737 unsigned int shrinker_disabled:1;738 unsigned int copy_gc_enabled:1;739 unsigned int idle_max_writeback_rate_enabled:1;740 741#define BUCKET_HASH_BITS 12742 struct hlist_head bucket_hash[1 << BUCKET_HASH_BITS];743};744 745struct bbio {746 unsigned int submit_time_us;747 union {748 struct bkey key;749 uint64_t _pad[3];750 /*751 * We only need pad = 3 here because we only ever carry around a752 * single pointer - i.e. the pointer we're doing io to/from.753 */754 };755 struct bio bio;756};757 758#define BTREE_PRIO USHRT_MAX759#define INITIAL_PRIO 32768U760 761#define btree_bytes(c) ((c)->btree_pages * PAGE_SIZE)762#define btree_blocks(b) \763 ((unsigned int) (KEY_SIZE(&b->key) >> (b)->c->block_bits))764 765#define btree_default_blocks(c) \766 ((unsigned int) ((PAGE_SECTORS * (c)->btree_pages) >> (c)->block_bits))767 768#define bucket_bytes(ca) ((ca)->sb.bucket_size << 9)769#define block_bytes(ca) ((ca)->sb.block_size << 9)770 771static inline unsigned int meta_bucket_pages(struct cache_sb *sb)772{773 unsigned int n, max_pages;774 775 max_pages = min_t(unsigned int,776 __rounddown_pow_of_two(USHRT_MAX) / PAGE_SECTORS,777 MAX_ORDER_NR_PAGES);778 779 n = sb->bucket_size / PAGE_SECTORS;780 if (n > max_pages)781 n = max_pages;782 783 return n;784}785 786static inline unsigned int meta_bucket_bytes(struct cache_sb *sb)787{788 return meta_bucket_pages(sb) << PAGE_SHIFT;789}790 791#define prios_per_bucket(ca) \792 ((meta_bucket_bytes(&(ca)->sb) - sizeof(struct prio_set)) / \793 sizeof(struct bucket_disk))794 795#define prio_buckets(ca) \796 DIV_ROUND_UP((size_t) (ca)->sb.nbuckets, prios_per_bucket(ca))797 798static inline size_t sector_to_bucket(struct cache_set *c, sector_t s)799{800 return s >> c->bucket_bits;801}802 803static inline sector_t bucket_to_sector(struct cache_set *c, size_t b)804{805 return ((sector_t) b) << c->bucket_bits;806}807 808static inline sector_t bucket_remainder(struct cache_set *c, sector_t s)809{810 return s & (c->cache->sb.bucket_size - 1);811}812 813static inline size_t PTR_BUCKET_NR(struct cache_set *c,814 const struct bkey *k,815 unsigned int ptr)816{817 return sector_to_bucket(c, PTR_OFFSET(k, ptr));818}819 820static inline struct bucket *PTR_BUCKET(struct cache_set *c,821 const struct bkey *k,822 unsigned int ptr)823{824 return c->cache->buckets + PTR_BUCKET_NR(c, k, ptr);825}826 827static inline uint8_t gen_after(uint8_t a, uint8_t b)828{829 uint8_t r = a - b;830 831 return r > 128U ? 0 : r;832}833 834static inline uint8_t ptr_stale(struct cache_set *c, const struct bkey *k,835 unsigned int i)836{837 return gen_after(PTR_BUCKET(c, k, i)->gen, PTR_GEN(k, i));838}839 840static inline bool ptr_available(struct cache_set *c, const struct bkey *k,841 unsigned int i)842{843 return (PTR_DEV(k, i) < MAX_CACHES_PER_SET) && c->cache;844}845 846/* Btree key macros */847 848/*849 * This is used for various on disk data structures - cache_sb, prio_set, bset,850 * jset: The checksum is _always_ the first 8 bytes of these structs851 */852#define csum_set(i) \853 bch_crc64(((void *) (i)) + sizeof(uint64_t), \854 ((void *) bset_bkey_last(i)) - \855 (((void *) (i)) + sizeof(uint64_t)))856 857/* Error handling macros */858 859#define btree_bug(b, ...) \860do { \861 if (bch_cache_set_error((b)->c, __VA_ARGS__)) \862 dump_stack(); \863} while (0)864 865#define cache_bug(c, ...) \866do { \867 if (bch_cache_set_error(c, __VA_ARGS__)) \868 dump_stack(); \869} while (0)870 871#define btree_bug_on(cond, b, ...) \872do { \873 if (cond) \874 btree_bug(b, __VA_ARGS__); \875} while (0)876 877#define cache_bug_on(cond, c, ...) \878do { \879 if (cond) \880 cache_bug(c, __VA_ARGS__); \881} while (0)882 883#define cache_set_err_on(cond, c, ...) \884do { \885 if (cond) \886 bch_cache_set_error(c, __VA_ARGS__); \887} while (0)888 889/* Looping macros */890 891#define for_each_bucket(b, ca) \892 for (b = (ca)->buckets + (ca)->sb.first_bucket; \893 b < (ca)->buckets + (ca)->sb.nbuckets; b++)894 895static inline void cached_dev_put(struct cached_dev *dc)896{897 if (refcount_dec_and_test(&dc->count))898 schedule_work(&dc->detach);899}900 901static inline bool cached_dev_get(struct cached_dev *dc)902{903 if (!refcount_inc_not_zero(&dc->count))904 return false;905 906 /* Paired with the mb in cached_dev_attach */907 smp_mb__after_atomic();908 return true;909}910 911/*912 * bucket_gc_gen() returns the difference between the bucket's current gen and913 * the oldest gen of any pointer into that bucket in the btree (last_gc).914 */915 916static inline uint8_t bucket_gc_gen(struct bucket *b)917{918 return b->gen - b->last_gc;919}920 921#define BUCKET_GC_GEN_MAX 96U922 923#define kobj_attribute_write(n, fn) \924 static struct kobj_attribute ksysfs_##n = __ATTR(n, 0200, NULL, fn)925 926#define kobj_attribute_rw(n, show, store) \927 static struct kobj_attribute ksysfs_##n = \928 __ATTR(n, 0600, show, store)929 930static inline void wake_up_allocators(struct cache_set *c)931{932 struct cache *ca = c->cache;933 934 wake_up_process(ca->alloc_thread);935}936 937static inline void closure_bio_submit(struct cache_set *c,938 struct bio *bio,939 struct closure *cl)940{941 closure_get(cl);942 if (unlikely(test_bit(CACHE_SET_IO_DISABLE, &c->flags))) {943 bio->bi_status = BLK_STS_IOERR;944 bio_endio(bio);945 return;946 }947 submit_bio_noacct(bio);948}949 950/*951 * Prevent the kthread exits directly, and make sure when kthread_stop()952 * is called to stop a kthread, it is still alive. If a kthread might be953 * stopped by CACHE_SET_IO_DISABLE bit set, wait_for_kthread_stop() is954 * necessary before the kthread returns.955 */956static inline void wait_for_kthread_stop(void)957{958 while (!kthread_should_stop()) {959 set_current_state(TASK_INTERRUPTIBLE);960 schedule();961 }962}963 964/* Forward declarations */965 966void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio);967void bch_count_io_errors(struct cache *ca, blk_status_t error,968 int is_read, const char *m);969void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio,970 blk_status_t error, const char *m);971void bch_bbio_endio(struct cache_set *c, struct bio *bio,972 blk_status_t error, const char *m);973void bch_bbio_free(struct bio *bio, struct cache_set *c);974struct bio *bch_bbio_alloc(struct cache_set *c);975 976void __bch_submit_bbio(struct bio *bio, struct cache_set *c);977void bch_submit_bbio(struct bio *bio, struct cache_set *c,978 struct bkey *k, unsigned int ptr);979 980uint8_t bch_inc_gen(struct cache *ca, struct bucket *b);981void bch_rescale_priorities(struct cache_set *c, int sectors);982 983bool bch_can_invalidate_bucket(struct cache *ca, struct bucket *b);984void __bch_invalidate_one_bucket(struct cache *ca, struct bucket *b);985 986void __bch_bucket_free(struct cache *ca, struct bucket *b);987void bch_bucket_free(struct cache_set *c, struct bkey *k);988 989long bch_bucket_alloc(struct cache *ca, unsigned int reserve, bool wait);990int __bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve,991 struct bkey *k, bool wait);992int bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve,993 struct bkey *k, bool wait);994bool bch_alloc_sectors(struct cache_set *c, struct bkey *k,995 unsigned int sectors, unsigned int write_point,996 unsigned int write_prio, bool wait);997bool bch_cached_dev_error(struct cached_dev *dc);998 999__printf(2, 3)1000bool bch_cache_set_error(struct cache_set *c, const char *fmt, ...);1001 1002int bch_prio_write(struct cache *ca, bool wait);1003void bch_write_bdev_super(struct cached_dev *dc, struct closure *parent);1004 1005extern struct workqueue_struct *bcache_wq;1006extern struct workqueue_struct *bch_journal_wq;1007extern struct workqueue_struct *bch_flush_wq;1008extern struct mutex bch_register_lock;1009extern struct list_head bch_cache_sets;1010 1011extern const struct kobj_type bch_cached_dev_ktype;1012extern const struct kobj_type bch_flash_dev_ktype;1013extern const struct kobj_type bch_cache_set_ktype;1014extern const struct kobj_type bch_cache_set_internal_ktype;1015extern const struct kobj_type bch_cache_ktype;1016 1017void bch_cached_dev_release(struct kobject *kobj);1018void bch_flash_dev_release(struct kobject *kobj);1019void bch_cache_set_release(struct kobject *kobj);1020void bch_cache_release(struct kobject *kobj);1021 1022int bch_uuid_write(struct cache_set *c);1023void bcache_write_super(struct cache_set *c);1024 1025int bch_flash_dev_create(struct cache_set *c, uint64_t size);1026 1027int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c,1028 uint8_t *set_uuid);1029void bch_cached_dev_detach(struct cached_dev *dc);1030int bch_cached_dev_run(struct cached_dev *dc);1031void bcache_device_stop(struct bcache_device *d);1032 1033void bch_cache_set_unregister(struct cache_set *c);1034void bch_cache_set_stop(struct cache_set *c);1035 1036struct cache_set *bch_cache_set_alloc(struct cache_sb *sb);1037void bch_btree_cache_free(struct cache_set *c);1038int bch_btree_cache_alloc(struct cache_set *c);1039void bch_moving_init_cache_set(struct cache_set *c);1040int bch_open_buckets_alloc(struct cache_set *c);1041void bch_open_buckets_free(struct cache_set *c);1042 1043int bch_cache_allocator_start(struct cache *ca);1044 1045void bch_debug_exit(void);1046void bch_debug_init(void);1047void bch_request_exit(void);1048int bch_request_init(void);1049void bch_btree_exit(void);1050int bch_btree_init(void);1051 1052#endif /* _BCACHE_H */1053