Signed-off-by: Kent Overstreet <koverstreet@xxxxxxxxxx> --- drivers/md/bcache/alloc.c | 615 ++++++++++++++++++++ drivers/md/bcache/io.c | 136 +++++ drivers/md/bcache/request.c | 1347 +++++++++++++++++++++++++++++++++++++++++++ drivers/md/bcache/request.h | 60 ++ 4 files changed, 2158 insertions(+) diff --git a/drivers/md/bcache/alloc.c b/drivers/md/bcache/alloc.c new file mode 100644 index 0000000..52d9a7c --- /dev/null +++ b/drivers/md/bcache/alloc.c @@ -0,0 +1,615 @@ + +#include "bcache.h" +#include "btree.h" + +#include <linux/random.h> + +/* + * Allocation in bcache is done in terms of buckets: + * + * Each bucket has associated an 8 bit gen; this gen corresponds to the gen in + * btree pointers - they must match for the pointer to be considered valid. + * + * Thus (assuming a bucket has no dirty data or metadata in it) we can reuse a + * bucket simply by incrementing its gen. + * + * The gens (along with the priorities; it's really the gens are important but + * the code is named as if it's the priorities) are written in an arbitrary list + * of buckets on disk, with a pointer to them in the journal header. + * + * When we invalidate a bucket, we have to write its new gen to disk and wait + * for that write to complete before we use it - otherwise after a crash we + * could have pointers that appeared to be good but pointed to data that had + * been overwritten. + * + * Since the gens and priorities are all stored contiguously on disk, we can + * batch this up: We fill up the free_inc list with freshly invalidated buckets, + * call prio_write() - and when prio_write() eventually finishes it toggles + * c->prio_written and the buckets in free_inc are now ready to be used. When + * the free_inc list empties, we toggle c->prio_written and the cycle repeats. + * + * free_inc isn't the only freelist - if it was, we'd often to sleep while + * priorities and gens were being written before we could allocate. c->free is a + * smaller freelist, and buckets on that list are always ready to be used. + * + * If we've got discards enabled, that happens when a bucket moves from the + * free_inc list to the free list. + * + * There is another freelist, because sometimes we have buckets that we know + * have nothing pointing into them - these we can reuse without waiting for + * priorities to be rewritten. These come from freed btree nodes and buckets + * that garbage collection discovered no longer had valid keys pointing into + * them (because they were overwritten). That's the unused list - buckets on the + * unused list move to the free list, optionally being discarded in the process. + * + * It's also important to ensure that gens don't wrap around - with respect to + * either the oldest gen in the btree or the gen on disk. This is quite + * difficult to do in practice, but we explicitly guard against it anyways - if + * a bucket is in danger of wrapping around we simply skip invalidating it that + * time around, and we garbage collect or rewrite the priorities sooner than we + * would have otherwise. + * + * pop_bucket() allocates a single bucket from a specific cache. + * + * pop_bucket_set() allocates one or more buckets from different caches out of a + * cache set. + * + * free_some_buckets() drives all the processes described above. It's called + * from pop_bucket() and a few other places that need to make sure free buckets + * are ready. + * + * invalidate_buckets_(lru|fifo)() find buckets that are available to be + * invalidated, and then invalidate them and stick them on the free_inc list - + * in either lru or fifo order. + */ + +#define MAX_IN_FLIGHT_DISCARDS 8 + +static void do_discard(struct cache *); + +/* Bucket heap / gen */ + +uint8_t bch_inc_gen(struct cache *ca, struct bucket *b) +{ + uint8_t ret = ++b->gen; + + ca->set->need_gc = max(ca->set->need_gc, bucket_gc_gen(b)); + WARN_ON_ONCE(ca->set->need_gc > BUCKET_GC_GEN_MAX); + + if (CACHE_SYNC(&ca->set->sb)) { + ca->need_save_prio = max(ca->need_save_prio, bucket_disk_gen(b)); + WARN_ON_ONCE(ca->need_save_prio > BUCKET_DISK_GEN_MAX); + } + + return ret; +} + +void bch_rescale_priorities(struct cache_set *c, int sectors) +{ + struct cache *ca; + struct bucket *b; + unsigned next = c->nbuckets * c->sb.bucket_size / 1024; + int r; + + atomic_sub(sectors, &c->rescale); + + do { + r = atomic_read(&c->rescale); + + if (r >= 0) + return; + } while (atomic_cmpxchg(&c->rescale, r, r + next) != r); + + mutex_lock(&c->bucket_lock); + + c->min_prio = USHRT_MAX; + + for_each_cache(ca, c) + for_each_bucket(b, ca) + if (b->prio && + b->prio != BTREE_PRIO && + !atomic_read(&b->pin)) { + b->prio--; + c->min_prio = min(c->min_prio, b->prio); + } + + mutex_unlock(&c->bucket_lock); +} + +static long pop_freed(struct cache *ca) +{ + long r; + + if ((!CACHE_SYNC(&ca->set->sb) || + !atomic_read(&ca->set->prio_blocked)) && + fifo_pop(&ca->unused, r)) + return r; + + if ((!CACHE_SYNC(&ca->set->sb) || + atomic_read(&ca->prio_written) > 0) && + fifo_pop(&ca->free_inc, r)) + return r; + + return -1; +} + +/* Discard/TRIM */ + +struct discard { + struct list_head list; + struct work_struct work; + struct cache *ca; + long bucket; + + struct bio bio; + struct bio_vec bv; +}; + +static void discard_finish(struct work_struct *w) +{ + struct discard *d = container_of(w, struct discard, work); + struct cache *ca = d->ca; + char buf[BDEVNAME_SIZE]; + bool run = false; + + if (!test_bit(BIO_UPTODATE, &d->bio.bi_flags)) { + printk(KERN_NOTICE "bcache: discard error on %s, disabling\n", + bdevname(ca->bdev, buf)); + d->ca->discard = 0; + } + + mutex_lock(&ca->set->bucket_lock); + if (fifo_empty(&ca->free) || + fifo_used(&ca->free) == 8) + run = true; + + fifo_push(&ca->free, d->bucket); + + list_add(&d->list, &ca->discards); + + do_discard(ca); + mutex_unlock(&ca->set->bucket_lock); + + if (run) + closure_wake_up(&ca->set->bucket_wait); + + closure_put(&ca->set->cl); +} + +static void discard_endio(struct bio *bio, int error) +{ + struct discard *d = container_of(bio, struct discard, bio); + + PREPARE_WORK(&d->work, discard_finish); + schedule_work(&d->work); +} + +static void discard_work(struct work_struct *w) +{ + struct discard *d = container_of(w, struct discard, work); + submit_bio(0, &d->bio); +} + +static void do_discard(struct cache *ca) +{ + struct request_queue *q = bdev_get_queue(ca->bdev); + int s = q->limits.logical_block_size; + + lockdep_assert_held(&ca->set->bucket_lock); + + while (ca->discard && + !atomic_read(&ca->set->closing) && + !list_empty(&ca->discards) && + fifo_free(&ca->free) >= MAX_IN_FLIGHT_DISCARDS) { + struct discard *d = list_first_entry(&ca->discards, + struct discard, list); + + d->bucket = pop_freed(ca); + if (d->bucket == -1) + break; + + list_del(&d->list); + closure_get(&ca->set->cl); + + bio_init(&d->bio); + memset(&d->bv, 0, sizeof(struct bio_vec)); + bio_set_prio(&d->bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0)); + + d->bio.bi_sector = bucket_to_sector(ca->set, d->bucket); + d->bio.bi_bdev = ca->bdev; + d->bio.bi_rw = REQ_WRITE|REQ_DISCARD; + d->bio.bi_max_vecs = 1; + d->bio.bi_io_vec = d->bio.bi_inline_vecs; + d->bio.bi_end_io = discard_endio; + + if (bio_add_pc_page(q, &d->bio, ca->discard_page, s, 0) < s) { + printk(KERN_DEBUG "bcache: bio_add_pc_page failed\n"); + ca->discard = 0; + fifo_push(&ca->free, d->bucket); + list_add(&d->list, &ca->discards); + break; + } + + d->bio.bi_size = bucket_bytes(ca); + + schedule_work(&d->work); + } +} + +void bch_free_discards(struct cache *ca) +{ + struct discard *d; + + while (!list_empty(&ca->discards)) { + d = list_first_entry(&ca->discards, struct discard, list); + cancel_work_sync(&d->work); + list_del(&d->list); + kfree(d); + } +} + +int bch_alloc_discards(struct cache *ca) +{ + for (int i = 0; i < MAX_IN_FLIGHT_DISCARDS; i++) { + struct discard *d = kzalloc(sizeof(*d), GFP_KERNEL); + if (!d) + return -ENOMEM; + + d->ca = ca; + INIT_WORK(&d->work, discard_work); + list_add(&d->list, &ca->discards); + } + + return 0; +} + +/* Allocation */ + +static inline bool can_inc_bucket_gen(struct bucket *b) +{ + return bucket_gc_gen(b) < BUCKET_GC_GEN_MAX && + bucket_disk_gen(b) < BUCKET_DISK_GEN_MAX; +} + +bool bch_bucket_add_unused(struct cache *ca, struct bucket *b) +{ + BUG_ON(GC_MARK(b) || GC_SECTORS_USED(b)); + + if (ca->prio_alloc == prio_buckets(ca) && + CACHE_REPLACEMENT(&ca->sb) == CACHE_REPLACEMENT_FIFO) + return false; + + b->prio = 0; + + if (can_inc_bucket_gen(b) && + fifo_push(&ca->unused, b - ca->buckets)) { + atomic_inc(&b->pin); + return true; + } + + return false; +} + +static bool can_invalidate_bucket(struct cache *ca, struct bucket *b) +{ + return GC_MARK(b) == GC_MARK_RECLAIMABLE && + !atomic_read(&b->pin) && + can_inc_bucket_gen(b); +} + +static void invalidate_one_bucket(struct cache *ca, struct bucket *b) +{ + bch_inc_gen(ca, b); + b->prio = INITIAL_PRIO; + atomic_inc(&b->pin); + fifo_push(&ca->free_inc, b - ca->buckets); +} + +static void invalidate_buckets_lru(struct cache *ca) +{ + unsigned bucket_prio(struct bucket *b) + { + return ((unsigned) (b->prio - ca->set->min_prio)) * + GC_SECTORS_USED(b); + } + + bool bucket_max_cmp(struct bucket *l, struct bucket *r) + { + return bucket_prio(l) < bucket_prio(r); + } + + bool bucket_min_cmp(struct bucket *l, struct bucket *r) + { + return bucket_prio(l) > bucket_prio(r); + } + + struct bucket *b; + + ca->heap.used = 0; + + for_each_bucket(b, ca) { + if (!can_invalidate_bucket(ca, b)) + continue; + + if (!GC_SECTORS_USED(b)) { + if (!bch_bucket_add_unused(ca, b)) + return; + } else { + if (!heap_full(&ca->heap)) + heap_add(&ca->heap, b, bucket_max_cmp); + else if (bucket_max_cmp(b, heap_peek(&ca->heap))) { + ca->heap.data[0] = b; + heap_sift(&ca->heap, 0, bucket_max_cmp); + } + } + } + + if (ca->heap.used * 2 < ca->heap.size) + bch_queue_gc(ca->set); + + for (ssize_t i = ca->heap.used / 2 - 1; i >= 0; --i) + heap_sift(&ca->heap, i, bucket_min_cmp); + + while (!fifo_full(&ca->free_inc)) { + if (!heap_pop(&ca->heap, b, bucket_min_cmp)) { + /* We don't want to be calling invalidate_buckets() + * multiple times when it can't do anything + */ + ca->invalidate_needs_gc = 1; + bch_queue_gc(ca->set); + return; + } + + invalidate_one_bucket(ca, b); + } +} + +static void invalidate_buckets_fifo(struct cache *ca) +{ + struct bucket *b; + size_t checked = 0; + + while (!fifo_full(&ca->free_inc)) { + if (ca->fifo_last_bucket < ca->sb.first_bucket || + ca->fifo_last_bucket >= ca->sb.nbuckets) + ca->fifo_last_bucket = ca->sb.first_bucket; + + b = ca->buckets + ca->fifo_last_bucket++; + + if (can_invalidate_bucket(ca, b)) + invalidate_one_bucket(ca, b); + + if (++checked >= ca->sb.nbuckets) { + ca->invalidate_needs_gc = 1; + bch_queue_gc(ca->set); + return; + } + } +} + +static void invalidate_buckets_random(struct cache *ca) +{ + struct bucket *b; + size_t checked = 0; + + while (!fifo_full(&ca->free_inc)) { + size_t n; + get_random_bytes(&n, sizeof(n)); + + n %= (size_t) (ca->sb.nbuckets - ca->sb.first_bucket); + n += ca->sb.first_bucket; + + b = ca->buckets + n; + + if (can_invalidate_bucket(ca, b)) + invalidate_one_bucket(ca, b); + + if (++checked >= ca->sb.nbuckets / 2) { + ca->invalidate_needs_gc = 1; + bch_queue_gc(ca->set); + return; + } + } +} + +static void invalidate_buckets(struct cache *ca) +{ + /* free_some_buckets() may just need to write priorities to keep gens + * from wrapping around + */ + if (!ca->set->gc_mark_valid || + ca->invalidate_needs_gc) + return; + + switch (CACHE_REPLACEMENT(&ca->sb)) { + case CACHE_REPLACEMENT_LRU: + invalidate_buckets_lru(ca); + break; + case CACHE_REPLACEMENT_FIFO: + invalidate_buckets_fifo(ca); + break; + case CACHE_REPLACEMENT_RANDOM: + invalidate_buckets_random(ca); + break; + } +} + +bool bch_can_save_prios(struct cache *ca) +{ + return ((ca->need_save_prio > 64 || + (ca->set->gc_mark_valid && + !ca->invalidate_needs_gc)) && + !atomic_read(&ca->prio_written) && + !atomic_read(&ca->set->prio_blocked)); +} + +void bch_free_some_buckets(struct cache *ca) +{ + long r; + lockdep_assert_held(&ca->set->bucket_lock); + + /* + * XXX: do_discard(), prio_write() take refcounts on the cache set. How + * do we know that refcount is nonzero? + */ + + if (ca->discard) + do_discard(ca); + else + while (!fifo_full(&ca->free) && + (r = pop_freed(ca)) != -1) + fifo_push(&ca->free, r); + + while (ca->prio_alloc != prio_buckets(ca) && + fifo_pop(&ca->free, r)) { + struct bucket *b = ca->buckets + r; + ca->prio_next[ca->prio_alloc++] = r; + + SET_GC_MARK(b, GC_MARK_BTREE); + atomic_dec_bug(&b->pin); + } + + if (!CACHE_SYNC(&ca->set->sb)) { + if (fifo_empty(&ca->free_inc)) + invalidate_buckets(ca); + return; + } + + /* XXX: tracepoint for when c->need_save_prio > 64 */ + + if (ca->need_save_prio <= 64 && + fifo_used(&ca->unused) > ca->unused.size / 2) + return; + + if (atomic_read(&ca->prio_written) > 0 && + (fifo_empty(&ca->free_inc) || + ca->need_save_prio > 64)) + atomic_set(&ca->prio_written, 0); + + if (!bch_can_save_prios(ca)) + return; + + invalidate_buckets(ca); + + if (!fifo_empty(&ca->free_inc) || + ca->need_save_prio > 64) + bch_prio_write(ca); +} + +static long pop_bucket(struct cache *ca, int mark, + uint16_t write_prio, struct closure *cl) +{ + long r = -1; + unsigned watermark; + + if (mark == GC_MARK_BTREE) + watermark = 0; + else if (write_prio) + watermark = 8; + else + watermark = ca->free.size / 2; + +again: + bch_free_some_buckets(ca); + + if (fifo_used(&ca->free) > watermark && + fifo_pop(&ca->free, r)) { + struct bucket *b = ca->buckets + r; +#ifdef CONFIG_BCACHE_EDEBUG + long i; + for (unsigned j = 0; j < prio_buckets(ca); j++) + BUG_ON(ca->prio_buckets[j] == (uint64_t) r); + for (unsigned j = 0; j < ca->prio_alloc; j++) + BUG_ON(ca->prio_next[j] == (uint64_t) r); + + fifo_for_each(i, &ca->free) + BUG_ON(i == r); + fifo_for_each(i, &ca->free_inc) + BUG_ON(i == r); + fifo_for_each(i, &ca->unused) + BUG_ON(i == r); +#endif + BUG_ON(atomic_read(&b->pin) != 1); + + SET_GC_MARK(b, mark); + SET_GC_SECTORS_USED(b, ca->sb.bucket_size); + b->prio = (mark == GC_MARK_BTREE) + ? BTREE_PRIO : INITIAL_PRIO; + + return r; + } + + pr_debug("no free buckets, prio_written %i, blocked %i, " + "free %zu, free_inc %zu, unused %zu", + atomic_read(&ca->prio_written), + atomic_read(&ca->set->prio_blocked), fifo_used(&ca->free), + fifo_used(&ca->free_inc), fifo_used(&ca->unused)); + + if (cl) { + if (closure_blocking(cl)) + mutex_unlock(&ca->set->bucket_lock); + + closure_wait_event(&ca->set->bucket_wait, cl, + atomic_read(&ca->prio_written) > 0 || + bch_can_save_prios(ca)); + + if (closure_blocking(cl)) { + mutex_lock(&ca->set->bucket_lock); + goto again; + } + } + + return -1; +} + +void bch_unpop_bucket(struct cache_set *c, struct bkey *k) +{ + for (unsigned i = 0; i < KEY_PTRS(k); i++) { + struct bucket *b = PTR_BUCKET(c, k, i); + + SET_GC_MARK(b, 0); + SET_GC_SECTORS_USED(b, 0); + bch_bucket_add_unused(PTR_CACHE(c, k, i), b); + } +} + +int __bch_pop_bucket_set(struct cache_set *c, int mark, uint16_t write_prio, + struct bkey *k, int n, struct closure *cl) +{ + lockdep_assert_held(&c->bucket_lock); + BUG_ON(!n || n > c->caches_loaded || n > 8); + + bkey_init(k); + + /* sort by free space/prio of oldest data in caches */ + + for (int i = 0; i < n; i++) { + struct cache *ca = c->cache_by_alloc[i]; + long b = pop_bucket(ca, mark, write_prio, cl); + + if (b == -1) + goto err; + + k->ptr[i] = PTR(ca->buckets[b].gen, + bucket_to_sector(c, b), + ca->sb.nr_this_dev); + + SET_KEY_PTRS(k, i + 1); + } + + return 0; +err: + bch_unpop_bucket(c, k); + __bkey_put(c, k); + return -1; +} + +int bch_pop_bucket_set(struct cache_set *c, int mark, uint16_t write_prio, + struct bkey *k, int n, struct closure *cl) +{ + int ret; + mutex_lock(&c->bucket_lock); + ret = __bch_pop_bucket_set(c, mark, write_prio, k, n, cl); + mutex_unlock(&c->bucket_lock); + return ret; +} diff --git a/drivers/md/bcache/io.c b/drivers/md/bcache/io.c new file mode 100644 index 0000000..4202304 --- /dev/null +++ b/drivers/md/bcache/io.c @@ -0,0 +1,136 @@ + +#include "bcache.h" +#include "bset.h" +#include "debug.h" + +/* Bios with headers */ + +void bch_bbio_free(struct bio *bio, struct cache_set *c) +{ + struct bbio *b = container_of(bio, struct bbio, bio); + mempool_free(b, c->bio_meta); +} + +struct bio *bch_bbio_alloc(struct cache_set *c) +{ + struct bbio *b = mempool_alloc(c->bio_meta, GFP_NOIO); + struct bio *bio = &b->bio; + + bio_init(bio); + bio->bi_flags |= BIO_POOL_NONE << BIO_POOL_OFFSET; + bio->bi_max_vecs = bucket_pages(c); + bio->bi_io_vec = bio->bi_inline_vecs; + + return bio; +} + +void __bch_submit_bbio(struct bio *bio, struct cache_set *c) +{ + struct bbio *b = container_of(bio, struct bbio, bio); + + bio->bi_sector = PTR_OFFSET(&b->key, 0); + bio->bi_bdev = PTR_CACHE(c, &b->key, 0)->bdev; + + b->submit_time_us = local_clock_us(); + closure_bio_submit(bio, bio->bi_private); +} + +void bch_submit_bbio(struct bio *bio, struct cache_set *c, + struct bkey *k, unsigned ptr) +{ + struct bbio *b = container_of(bio, struct bbio, bio); + bch_bkey_copy_single_ptr(&b->key, k, ptr); + __bch_submit_bbio(bio, c); +} + +/* IO errors */ + +void bch_count_io_errors(struct cache *ca, int error, const char *m) +{ + /* + * The halflife of an error is: + * log2(1/2)/log2(127/128) * refresh ~= 88 * refresh + */ + + if (ca->set->error_decay) { + unsigned count = atomic_inc_return(&ca->io_count); + + while (count > ca->set->error_decay) { + unsigned errors; + unsigned old = count; + unsigned new = count - ca->set->error_decay; + + /* + * First we subtract refresh from count; each time we + * succesfully do so, we rescale the errors once: + */ + + count = atomic_cmpxchg(&ca->io_count, old, new); + + if (count == old) { + count = new; + + errors = atomic_read(&ca->io_errors); + do { + old = errors; + new = ((uint64_t) errors * 127) / 128; + errors = atomic_cmpxchg(&ca->io_errors, + old, new); + } while (old != errors); + } + } + } + + if (error) { + char buf[BDEVNAME_SIZE]; + unsigned errors = atomic_add_return(1 << IO_ERROR_SHIFT, + &ca->io_errors); + errors >>= IO_ERROR_SHIFT; + + if (errors < ca->set->error_limit) + err_printk("%s: IO error on %s, recovering\n", + bdevname(ca->bdev, buf), m); + else + bch_cache_set_error(ca->set, "%s: too many IO errors %s", + bdevname(ca->bdev, buf), m); + } +} + +void bch_bbio_count_io_errors(struct cache_set *c, struct bio *bio, + int error, const char *m) +{ + struct bbio *b = container_of(bio, struct bbio, bio); + struct cache *ca = PTR_CACHE(c, &b->key, 0); + + unsigned threshold = bio->bi_rw & REQ_WRITE + ? c->congested_write_threshold_us + : c->congested_read_threshold_us; + + if (threshold) { + unsigned t = local_clock_us(); + + int us = t - b->submit_time_us; + int congested = atomic_read(&c->congested); + + if (us > (int) threshold) { + int ms = us / 1024; + c->congested_last_us = t; + + ms = min(ms, CONGESTED_MAX + congested); + atomic_sub(ms, &c->congested); + } else if (congested < 0) + atomic_inc(&c->congested); + } + + bch_count_io_errors(ca, error, m); +} + +void bch_bbio_endio(struct cache_set *c, struct bio *bio, + int error, const char *m) +{ + struct closure *cl = bio->bi_private; + + bch_bbio_count_io_errors(c, bio, error, m); + bio_put(bio); + closure_put(cl); +} diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c new file mode 100644 index 0000000..1fd105b --- /dev/null +++ b/drivers/md/bcache/request.c @@ -0,0 +1,1347 @@ + +#include "bcache.h" +#include "btree.h" +#include "debug.h" +#include "request.h" + +#include <linux/cgroup.h> +#include <linux/module.h> +#include <linux/hash.h> +#include <linux/random.h> +#include "blk-cgroup.h" + +#include <trace/events/bcache.h> + +#define CUTOFF_CACHE_ADD 95 +#define CUTOFF_CACHE_READA 90 +#define CUTOFF_WRITEBACK 50 +#define CUTOFF_WRITEBACK_SYNC 75 + +struct kmem_cache *bch_search_cache; + +static void check_should_skip(struct cached_dev *, struct search *); + +/* Cgroup interface */ + +#ifdef CONFIG_CGROUP_BCACHE +static struct bch_cgroup bcache_default_cgroup = { .cache_mode = -1 }; + +static struct bch_cgroup *cgroup_to_bcache(struct cgroup *cgroup) +{ + struct cgroup_subsys_state *css; + return cgroup && + (css = cgroup_subsys_state(cgroup, bcache_subsys_id)) + ? container_of(css, struct bch_cgroup, css) + : &bcache_default_cgroup; +} + +struct bch_cgroup *bch_bio_to_cgroup(struct bio *bio) +{ + struct cgroup_subsys_state *css = bio->bi_css + ? cgroup_subsys_state(bio->bi_css->cgroup, bcache_subsys_id) + : task_subsys_state(current, bcache_subsys_id); + + return css + ? container_of(css, struct bch_cgroup, css) + : &bcache_default_cgroup; +} + +static ssize_t cache_mode_read(struct cgroup *cgrp, struct cftype *cft, + struct file *file, + char __user *buf, size_t nbytes, loff_t *ppos) +{ + char tmp[1024]; + int len = snprint_string_list(tmp, PAGE_SIZE, bch_cache_modes, + cgroup_to_bcache(cgrp)->cache_mode + 1); + + if (len < 0) + return len; + + return simple_read_from_buffer(buf, nbytes, ppos, tmp, len); +} + +static int cache_mode_write(struct cgroup *cgrp, struct cftype *cft, + const char *buf) +{ + int v = read_string_list(buf, bch_cache_modes); + if (v < 0) + return v; + + cgroup_to_bcache(cgrp)->cache_mode = v - 1; + return 0; +} + +static u64 bch_verify_read(struct cgroup *cgrp, struct cftype *cft) +{ + return cgroup_to_bcache(cgrp)->verify; +} + +static int bch_verify_write(struct cgroup *cgrp, struct cftype *cft, u64 val) +{ + cgroup_to_bcache(cgrp)->verify = val; + return 0; +} + +static u64 bch_cache_hits_read(struct cgroup *cgrp, struct cftype *cft) +{ + struct bch_cgroup *bcachecg = cgroup_to_bcache(cgrp); + return atomic_read(&bcachecg->stats.cache_hits); +} + +static u64 bch_cache_misses_read(struct cgroup *cgrp, struct cftype *cft) +{ + struct bch_cgroup *bcachecg = cgroup_to_bcache(cgrp); + return atomic_read(&bcachecg->stats.cache_misses); +} + +static u64 bch_cache_bypass_hits_read(struct cgroup *cgrp, + struct cftype *cft) +{ + struct bch_cgroup *bcachecg = cgroup_to_bcache(cgrp); + return atomic_read(&bcachecg->stats.cache_bypass_hits); +} + +static u64 bch_cache_bypass_misses_read(struct cgroup *cgrp, + struct cftype *cft) +{ + struct bch_cgroup *bcachecg = cgroup_to_bcache(cgrp); + return atomic_read(&bcachecg->stats.cache_bypass_misses); +} + +static struct cftype bch_files[] = { + { + .name = "cache_mode", + .read = cache_mode_read, + .write_string = cache_mode_write, + }, + { + .name = "verify", + .read_u64 = bch_verify_read, + .write_u64 = bch_verify_write, + }, + { + .name = "cache_hits", + .read_u64 = bch_cache_hits_read, + }, + { + .name = "cache_misses", + .read_u64 = bch_cache_misses_read, + }, + { + .name = "cache_bypass_hits", + .read_u64 = bch_cache_bypass_hits_read, + }, + { + .name = "cache_bypass_misses", + .read_u64 = bch_cache_bypass_misses_read, + }, + { } /* terminate */ +}; + +static void init_bch_cgroup(struct bch_cgroup *cg) +{ + cg->cache_mode = -1; +} + +static struct cgroup_subsys_state *bcachecg_create(struct cgroup *cgroup) +{ + struct bch_cgroup *cg; + + cg = kzalloc(sizeof(*cg), GFP_KERNEL); + if (!cg) + return ERR_PTR(-ENOMEM); + init_bch_cgroup(cg); + return &cg->css; +} + +static void bcachecg_destroy(struct cgroup *cgroup) +{ + struct bch_cgroup *cg = cgroup_to_bcache(cgroup); + free_css_id(&bcache_subsys, &cg->css); + kfree(cg); +} + +struct cgroup_subsys bcache_subsys = { + .create = bcachecg_create, + .destroy = bcachecg_destroy, + .subsys_id = bcache_subsys_id, + .name = "bcache", + .module = THIS_MODULE, +}; +EXPORT_SYMBOL_GPL(bcache_subsys); +#endif + +static unsigned cache_mode(struct cached_dev *dc, struct bio *bio) +{ +#ifdef CONFIG_CGROUP_BCACHE + int r = bch_bio_to_cgroup(bio)->cache_mode; + if (r >= 0) + return r; +#endif + return BDEV_CACHE_MODE(&dc->sb); +} + +static bool verify(struct cached_dev *dc, struct bio *bio) +{ +#ifdef CONFIG_CGROUP_BCACHE + if (bch_bio_to_cgroup(bio)->verify) + return true; +#endif + return dc->verify; +} + +static void bio_csum(struct bio *bio, struct bkey *k) +{ + struct bio_vec *bv; + uint64_t csum = 0; + int i; + + bio_for_each_segment(bv, bio, i) { + void *d = kmap(bv->bv_page) + bv->bv_offset; + csum = crc64_update(csum, d, bv->bv_len); + kunmap(bv->bv_page); + } + + k->ptr[KEY_PTRS(k)] = csum & (~0ULL >> 1); +} + +/* Insert data into cache */ + +static void bio_invalidate(struct closure *cl) +{ + struct btree_op *op = container_of(cl, struct btree_op, cl); + struct bio *bio = op->cache_bio; + + pr_debug("invalidating %i sectors from %llu", + bio_sectors(bio), (uint64_t) bio->bi_sector); + + while (bio_sectors(bio)) { + unsigned len = min(bio_sectors(bio), 1U << 14); + + if (bch_keylist_realloc(&op->keys, 0, op->c)) + goto out; + + bio->bi_sector += len; + bio->bi_size -= len << 9; + + bch_keylist_add(&op->keys, &KEY(op->inode, bio->bi_sector, len)); + } + + op->bio_insert_done = true; + bio_put(bio); +out: + continue_at(cl, bch_journal, bcache_wq); +} + +struct open_bucket { + struct list_head list; + struct task_struct *last; + unsigned sectors_free; + BKEY_PADDED(key); +}; + +void bch_open_buckets_free(struct cache_set *c) +{ + struct open_bucket *b; + + while (!list_empty(&c->data_buckets)) { + b = list_first_entry(&c->data_buckets, + struct open_bucket, list); + list_del(&b->list); + kfree(b); + } +} + +int bch_open_buckets_alloc(struct cache_set *c) +{ + spin_lock_init(&c->data_bucket_lock); + + for (int i = 0; i < 6; i++) { + struct open_bucket *b = kzalloc(sizeof(*b), GFP_KERNEL); + if (!b) + return -ENOMEM; + + list_add(&b->list, &c->data_buckets); + } + + return 0; +} + +/* + * We keep multiple buckets open for writes, and try to segregate different + * write streams for better cache utilization: first we look for a bucket where + * the last write to it was sequential with the current write, and failing that + * we look for a bucket that was last used by the same task. + * + * The ideas is if you've got multiple tasks pulling data into the cache at the + * same time, you'll get better cache utilization if you try to segregate their + * data and preserve locality. + * + * For example, say you've starting Firefox at the same time you're copying a + * bunch of files. Firefox will likely end up being fairly hot and stay in the + * cache awhile, but the data you copied might not be; if you wrote all that + * data to the same buckets it'd get invalidated at the same time. + * + * Both of those tasks will be doing fairly random IO so we can't rely on + * detecting sequential IO to segregate their data, but going off of the task + * should be a sane heuristic. + */ +static struct open_bucket *pick_data_bucket(struct cache_set *c, + const struct bkey *search, + struct task_struct *task, + struct bkey *alloc) +{ + struct open_bucket *ret, *ret_task = NULL; + + list_for_each_entry_reverse(ret, &c->data_buckets, list) + if (!bkey_cmp(&ret->key, search)) + goto found; + else if (ret->last == task) + ret_task = ret; + + ret = ret_task ?: list_first_entry(&c->data_buckets, + struct open_bucket, list); +found: + if (!ret->sectors_free && KEY_PTRS(alloc)) { + ret->sectors_free = c->sb.bucket_size; + bkey_copy(&ret->key, alloc); + bkey_init(alloc); + } + + if (!ret->sectors_free) + ret = NULL; + + return ret; +} + +/* + * Allocates some space in the cache to write to, and k to point to the newly + * allocated space, and updates KEY_SIZE(k) and KEY_OFFSET(k) (to point to the + * end of the newly allocated space). + * + * May allocate fewer sectors than @sectors, KEY_SIZE(k) indicates how many + * sectors were actually allocated. + * + * If s->writeback is true, will not fail. + */ +static bool bch_alloc_sectors(struct bkey *k, unsigned sectors, + struct search *s) +{ + struct cache_set *c = s->op.c; + struct open_bucket *b; + BKEY_PADDED(key) alloc; + struct closure cl, *w = NULL; + + if (s->writeback) { + closure_init_stack(&cl); + w = &cl; + } + + /* + * We might have to allocate a new bucket, which we can't do with a + * spinlock held. So if we have to allocate, we drop the lock, allocate + * and then retry. KEY_PTRS() indicates whether alloc points to + * allocated bucket(s). + */ + + bkey_init(&alloc.key); + spin_lock(&c->data_bucket_lock); + + while (!(b = pick_data_bucket(c, k, s->task, &alloc.key))) { + spin_unlock(&c->data_bucket_lock); + + if (bch_pop_bucket_set(c, GC_MARK_RECLAIMABLE, s->op.write_prio, + &alloc.key, 1, w)) + return false; + + spin_lock(&c->data_bucket_lock); + } + + /* + * If we had to allocate, we might race and not need to allocate the + * second time we call find_data_bucket(). If we allocated a bucket but + * didn't use it, drop the refcount pop_bucket_set() took: + */ + if (KEY_PTRS(&alloc.key)) + __bkey_put(c, &alloc.key); + + for (unsigned i = 0; i < KEY_PTRS(&b->key); i++) + EBUG_ON(ptr_stale(c, &b->key, i)); + + /* Set up the pointer to the space we're allocating: */ + + for (unsigned i = 0; i < KEY_PTRS(&b->key); i++) + k->ptr[i] = b->key.ptr[i]; + + sectors = min(sectors, b->sectors_free); + + SET_KEY_OFFSET(k, KEY_OFFSET(k) + sectors); + SET_KEY_SIZE(k, sectors); + SET_KEY_PTRS(k, KEY_PTRS(&b->key)); + + /* + * Move b to the end of the lru, and keep track of what this bucket was + * last used for: + */ + list_move_tail(&b->list, &c->data_buckets); + bkey_copy_key(&b->key, k); + b->last = s->task; + + b->sectors_free -= sectors; + + for (unsigned i = 0; i < KEY_PTRS(&b->key); i++) { + SET_PTR_OFFSET(&b->key, i, PTR_OFFSET(&b->key, i) + sectors); + + atomic_long_add(sectors, + &PTR_CACHE(c, &b->key, i)->sectors_written); + } + + if (b->sectors_free < c->sb.block_size) + b->sectors_free = 0; + + /* + * k takes refcounts on the buckets it points to until it's inserted + * into the btree, but if we're done with this bucket we just transfer + * get_data_bucket()'s refcount. + */ + if (b->sectors_free) + for (unsigned i = 0; i < KEY_PTRS(&b->key); i++) + atomic_inc(&PTR_BUCKET(c, &b->key, i)->pin); + + spin_unlock(&c->data_bucket_lock); + return true; +} + +static void bio_insert_error(struct closure *cl) +{ + struct btree_op *op = container_of(cl, struct btree_op, cl); + + /* + * Our data write just errored, which means we've got a bunch of keys to + * insert that point to data that wasn't succesfully written. + * + * We don't have to insert those keys but we still have to invalidate + * that region of the cache - so, if we just strip off all the pointers + * from the keys we'll accomplish just that. + */ + + struct bkey *src = op->keys.bottom, *dst = op->keys.bottom; + + while (src != op->keys.top) { + struct bkey *n = bkey_next(src); + + SET_KEY_PTRS(src, 0); + bkey_copy(dst, src); + + dst = bkey_next(dst); + src = n; + } + + op->keys.top = dst; + + bch_journal(cl); +} + +static void bio_insert_endio(struct bio *bio, int error) +{ + struct closure *cl = bio->bi_private; + struct btree_op *op = container_of(cl, struct btree_op, cl); + struct search *s = container_of(op, struct search, op); + + if (error) { + /* TODO: We could try to recover from this. */ + if (s->writeback) + s->error = error; + else if (s->write) + set_closure_fn(cl, bio_insert_error, bcache_wq); + else + set_closure_fn(cl, NULL, NULL); + } + + bch_bbio_endio(op->c, bio, error, "writing data to cache"); +} + +static void bio_insert_loop(struct closure *cl) +{ + struct btree_op *op = container_of(cl, struct btree_op, cl); + struct search *s = container_of(op, struct search, op); + struct bio *bio = op->cache_bio, *n; + + if (op->skip) + return bio_invalidate(cl); + + if (atomic_sub_return(bio_sectors(bio), &op->c->sectors_to_gc) < 0) { + set_gc_sectors(op->c); + bch_queue_gc(op->c); + } + + bio->bi_end_io = bio_insert_endio; + bio->bi_private = cl; + + do { + struct bkey *k; + struct bio_set *split = s->d + ? s->d->bio_split : op->c->bio_split; + + /* 1 for the device pointer and 1 for the chksum */ + if (bch_keylist_realloc(&op->keys, + 1 + (op->csum ? 1 : 0), + op->c)) + continue_at(cl, bch_journal, bcache_wq); + + k = op->keys.top; + bkey_init(k); + SET_KEY_INODE(k, op->inode); + SET_KEY_OFFSET(k, bio->bi_sector); + + if (!bch_alloc_sectors(k, bio_sectors(bio), s)) + goto err; + + n = bio_split(bio, KEY_SIZE(k), GFP_NOIO, split); + if (!n) { + __bkey_put(op->c, k); + continue_at(cl, bio_insert_loop, bcache_wq); + } + + if (s->writeback) { + SET_KEY_DIRTY(k, true); + + for (unsigned i = 0; i < KEY_PTRS(k); i++) + SET_GC_MARK(PTR_BUCKET(op->c, k, i), + GC_MARK_DIRTY); + } + + SET_KEY_CSUM(k, op->csum); + if (KEY_CSUM(k)) + bio_csum(n, k); + + pr_debug("%s", pkey(k)); + bch_keylist_push(&op->keys); + + trace_bcache_cache_insert(n, n->bi_sector, n->bi_bdev); + n->bi_rw |= REQ_WRITE; + bch_submit_bbio(n, op->c, k, 0); + } while (n != bio); + + op->bio_insert_done = true; + continue_at(cl, bch_journal, bcache_wq); +err: + /* bch_alloc_sectors() blocks if s->writeback = true */ + BUG_ON(s->writeback); + + /* + * But if it's not a writeback write we'd rather just bail out if + * there aren't any buckets ready to write to - it might take awhile and + * we might be starving btree writes for gc or something. + */ + + if (s->write) { + /* + * Writethrough write: We can't complete the write until we've + * updated the index. But we don't want to delay the write while + * we wait for buckets to be freed up, so just invalidate the + * rest of the write. + */ + op->skip = true; + return bio_invalidate(cl); + } else { + /* + * From a cache miss, we can just insert the keys for the data + * we have written or bail out if we didn't do anything. + */ + op->bio_insert_done = true; + + if (!bch_keylist_empty(&op->keys)) + continue_at(cl, bch_journal, bcache_wq); + else + closure_return(cl); + } +} + +void bch_bio_insert(struct closure *cl) +{ + struct btree_op *op = container_of(cl, struct btree_op, cl); + + bch_keylist_init(&op->keys); + bio_get(op->cache_bio); + bio_insert_loop(cl); +} + +void bch_btree_insert_async(struct closure *cl) +{ + struct btree_op *op = container_of(cl, struct btree_op, cl); + struct search *s = container_of(op, struct search, op); + + if (bch_btree_insert(op, op->c)) { + s->error = -ENOMEM; + op->bio_insert_done = true; + } + + if (op->bio_insert_done) { + bch_keylist_free(&op->keys); + closure_return(cl); + } else + continue_at(cl, bio_insert_loop, bcache_wq); +} + +/* Common code for the make_request functions */ + +static void request_endio(struct bio *bio, int error) +{ + struct closure *cl = bio->bi_private; + + if (error) { + struct search *s = container_of(cl, struct search, cl); + s->error = error; + /* Only cache read errors are recoverable */ + s->recoverable = false; + } + + bio_put(bio); + closure_put(cl); +} + +void bch_cache_read_endio(struct bio *bio, int error) +{ + struct bbio *b = container_of(bio, struct bbio, bio); + struct closure *cl = bio->bi_private; + struct search *s = container_of(cl, struct search, cl); + + /* + * If the bucket was reused while our bio was in flight, we might have + * read the wrong data. Set s->error but not error so it doesn't get + * counted against the cache device, but we'll still reread the data + * from the backing device. + */ + + if (error) + s->error = error; + else if (ptr_stale(s->op.c, &b->key, 0)) { + atomic_long_inc(&s->op.c->cache_read_races); + s->error = -EINTR; + } + + bch_bbio_endio(s->op.c, bio, error, "reading from cache"); +} + +static void bio_complete(struct search *s) +{ + if (s->orig_bio) { + if (s->error) + clear_bit(BIO_UPTODATE, &s->orig_bio->bi_flags); + + trace_bcache_request_end(s, s->orig_bio); + bio_endio(s->orig_bio, s->error); + s->orig_bio = NULL; + } +} + +static void do_bio_hook(struct search *s) +{ + struct bio *bio = &s->bio.bio; + memcpy(bio, s->orig_bio, sizeof(struct bio)); + + bio->bi_end_io = request_endio; + bio->bi_private = &s->cl; + atomic_set(&bio->bi_cnt, 3); +} + +static void search_free(struct closure *cl) +{ + struct search *s = container_of(cl, struct search, cl); + bio_complete(s); + + if (s->op.cache_bio) + bio_put(s->op.cache_bio); + + if (s->unaligned_bvec) + mempool_free(s->bio.bio.bi_io_vec, s->d->unaligned_bvec); + + closure_debug_destroy(cl); + mempool_free(s, s->d->c->search); +} + +static struct search *search_alloc(struct bio *bio, struct bcache_device *d) +{ + struct bio_vec *bv; + struct search *s = mempool_alloc(d->c->search, GFP_NOIO); + memset(s, 0, offsetof(struct search, op.keys)); + + __closure_init(&s->cl, NULL); + + s->op.inode = d->id; + s->op.c = d->c; + s->d = d; + s->op.lock = -1; + s->task = current; + s->orig_bio = bio; + s->write = (bio->bi_rw & REQ_WRITE) != 0; + s->op.flush_journal = (bio->bi_rw & REQ_FLUSH) != 0; + s->op.skip = (bio->bi_rw & REQ_DISCARD) != 0; + s->recoverable = 1; + do_bio_hook(s); + + if (bio->bi_size != bio_segments(bio) * PAGE_SIZE) { + bv = mempool_alloc(d->unaligned_bvec, GFP_NOIO); + memcpy(bv, bio_iovec(bio), + sizeof(struct bio_vec) * bio_segments(bio)); + + s->bio.bio.bi_io_vec = bv; + s->unaligned_bvec = 1; + } + + return s; +} + +static void btree_read_async(struct closure *cl) +{ + struct btree_op *op = container_of(cl, struct btree_op, cl); + + int ret = btree_root(search_recurse, op->c, op); + + if (ret == -EAGAIN) + continue_at(cl, btree_read_async, bcache_wq); + + closure_return(cl); +} + +/* Cached devices */ + +static void cached_dev_bio_complete(struct closure *cl) +{ + struct search *s = container_of(cl, struct search, cl); + struct cached_dev *dc = container_of(s->d, struct cached_dev, disk); + + search_free(cl); + cached_dev_put(dc); +} + +/* Process reads */ + +static void cached_dev_read_complete(struct closure *cl) +{ + struct search *s = container_of(cl, struct search, cl); + + if (s->cache_miss) + bio_put(s->cache_miss); + + if (s->op.cache_bio) { + int i; + struct bio_vec *bv; + + __bio_for_each_segment(bv, s->op.cache_bio, i, 0) + __free_page(bv->bv_page); + } + + cached_dev_bio_complete(cl); +} + +static void request_read_error(struct closure *cl) +{ + struct search *s = container_of(cl, struct search, cl); + struct bio_vec *bv; + int i; + + if (s->recoverable) { + /* The cache read failed, but we can retry from the backing + * device. + */ + pr_debug("recovering at sector %llu", + (uint64_t) s->orig_bio->bi_sector); + + s->error = 0; + bv = s->bio.bio.bi_io_vec; + do_bio_hook(s); + s->bio.bio.bi_io_vec = bv; + + if (!s->unaligned_bvec) + bio_for_each_segment(bv, s->orig_bio, i) + bv->bv_offset = 0, bv->bv_len = PAGE_SIZE; + else + memcpy(s->bio.bio.bi_io_vec, + bio_iovec(s->orig_bio), + sizeof(struct bio_vec) * + bio_segments(s->orig_bio)); + + /* XXX: invalidate cache */ + + trace_bcache_read_retry(&s->bio.bio); + closure_bio_submit(&s->bio.bio, &s->cl); + } + + continue_at(cl, cached_dev_read_complete, NULL); +} + +static void request_read_done(struct closure *cl) +{ + struct search *s = container_of(cl, struct search, cl); + struct cached_dev *dc = container_of(s->d, struct cached_dev, disk); + + /* + * s->cache_bio != NULL implies that we had a cache miss; cache_bio now + * contains data ready to be inserted into the cache. + * + * First, we copy the data we just read from cache_bio's bounce buffers + * to the buffers the original bio pointed to: + */ + + if (s->op.cache_bio) { + struct bio_vec *src, *dst; + unsigned src_offset, dst_offset, bytes; + void *dst_ptr; + + bio_reset(s->op.cache_bio); + s->op.cache_bio->bi_sector = s->cache_miss->bi_sector; + s->op.cache_bio->bi_bdev = s->cache_miss->bi_bdev; + s->op.cache_bio->bi_size = s->cache_bio_sectors << 9; + bio_map(s->op.cache_bio, NULL); + + src = bio_iovec(s->op.cache_bio); + dst = bio_iovec(s->cache_miss); + src_offset = src->bv_offset; + dst_offset = dst->bv_offset; + dst_ptr = kmap(dst->bv_page); + + while (1) { + if (dst_offset == dst->bv_offset + dst->bv_len) { + kunmap(dst->bv_page); + dst++; + if (dst == bio_iovec_idx(s->cache_miss, + s->cache_miss->bi_vcnt)) + break; + + dst_offset = dst->bv_offset; + dst_ptr = kmap(dst->bv_page); + } + + if (src_offset == src->bv_offset + src->bv_len) { + src++; + if (src == bio_iovec_idx(s->op.cache_bio, + s->op.cache_bio->bi_vcnt)) + BUG(); + + src_offset = src->bv_offset; + } + + bytes = min(dst->bv_offset + dst->bv_len - dst_offset, + src->bv_offset + src->bv_len - src_offset); + + memcpy(dst_ptr + dst_offset, + page_address(src->bv_page) + src_offset, + bytes); + + src_offset += bytes; + dst_offset += bytes; + } + } + + if (verify(dc, &s->bio.bio) && s->recoverable) + bch_data_verify(s); + + bio_complete(s); + + if (s->op.cache_bio && !atomic_read(&s->op.c->closing)) { + s->op.type = BTREE_REPLACE; + closure_call(bch_bio_insert, &s->op.cl, cl); + } + + continue_at(cl, cached_dev_read_complete, NULL); +} + +static void request_read_done_bh(struct closure *cl) +{ + struct search *s = container_of(cl, struct search, cl); + struct cached_dev *dc = container_of(s->d, struct cached_dev, disk); + + if (s->cache_miss && s->op.insert_collision) + bch_mark_cache_miss_collision(s); + + bch_mark_cache_accounting(s, !s->cache_miss, s->op.skip); + + if (s->error) + continue_at_nobarrier(cl, request_read_error, bcache_wq); + else if (s->op.cache_bio || verify(dc, &s->bio.bio)) + continue_at_nobarrier(cl, request_read_done, bcache_wq); + else + continue_at_nobarrier(cl, cached_dev_read_complete, NULL); +} + +static int cached_dev_cache_miss(struct btree *b, struct search *s, + struct bio *bio, unsigned sectors) +{ + int ret = 0; + unsigned reada; + struct cached_dev *dc = container_of(s->d, struct cached_dev, disk); + struct bio *miss; + + miss = bio_split(bio, sectors, GFP_NOIO, s->d->bio_split); + if (!miss) + return -EAGAIN; + + if (miss == bio) + s->op.lookup_done = true; + + if (s->cache_miss || s->op.skip) + goto out_submit; + + if (miss != bio || + (bio->bi_rw & REQ_RAHEAD) || + (bio->bi_rw & REQ_META) || + s->op.c->gc_stats.in_use >= CUTOFF_CACHE_READA) + reada = 0; + else { + reada = dc->readahead >> 9; + + if (bio_end(miss) + reada > bdev_sectors(miss->bi_bdev)) + reada = bdev_sectors(miss->bi_bdev) - bio_end(miss); + } + + s->cache_bio_sectors = bio_sectors(miss) + reada; + s->op.cache_bio = bio_alloc_bioset(GFP_NOWAIT, + DIV_ROUND_UP(s->cache_bio_sectors, PAGE_SECTORS), + dc->disk.bio_split); + + if (!s->op.cache_bio) + goto out_submit; + + s->op.cache_bio->bi_sector = miss->bi_sector; + s->op.cache_bio->bi_bdev = miss->bi_bdev; + s->op.cache_bio->bi_size = s->cache_bio_sectors << 9; + + s->op.cache_bio->bi_end_io = request_endio; + s->op.cache_bio->bi_private = &s->cl; + + /* btree_search_recurse()'s btree iterator is no good anymore */ + ret = -EINTR; + if (!bch_btree_insert_check_key(b, &s->op, s->op.cache_bio)) + goto out_put; + + bio_map(s->op.cache_bio, NULL); + if (bio_alloc_pages(s->op.cache_bio, __GFP_NOWARN|GFP_NOIO)) + goto out_put; + + s->cache_miss = miss; + bio_get(s->op.cache_bio); + + trace_bcache_cache_miss(s->orig_bio); + closure_bio_submit(s->op.cache_bio, &s->cl); + + return ret; +out_put: + bio_put(s->op.cache_bio); + s->op.cache_bio = NULL; +out_submit: + closure_bio_submit(miss, &s->cl); + return ret; +} + +static void request_read(struct cached_dev *dc, struct search *s) +{ + struct closure *cl = &s->cl; + + check_should_skip(dc, s); + closure_call(btree_read_async, &s->op.cl, cl); + + continue_at(cl, request_read_done_bh, NULL); +} + +/* Process writes */ + +static void cached_dev_write_complete(struct closure *cl) +{ + struct search *s = container_of(cl, struct search, cl); + struct cached_dev *dc = container_of(s->d, struct cached_dev, disk); + + up_read_non_owner(&dc->writeback_lock); + cached_dev_bio_complete(cl); +} + +static bool should_writeback(struct cached_dev *dc, struct bio *bio) +{ + unsigned threshold = (bio->bi_rw & REQ_SYNC) + ? CUTOFF_WRITEBACK_SYNC + : CUTOFF_WRITEBACK; + + return !atomic_read(&dc->disk.detaching) && + cache_mode(dc, bio) == CACHE_MODE_WRITEBACK && + dc->disk.c->gc_stats.in_use < threshold; +} + +static void request_write(struct cached_dev *dc, struct search *s) +{ + struct closure *cl = &s->cl; + struct bio *bio = &s->bio.bio; + struct bkey start, end; + start = KEY(dc->disk.id, bio->bi_sector, 0); + end = KEY(dc->disk.id, bio_end(bio), 0); + + bch_keybuf_check_overlapping(&s->op.c->moving_gc_keys, &start, &end); + + check_should_skip(dc, s); + down_read_non_owner(&dc->writeback_lock); + + if (bch_keybuf_check_overlapping(&dc->writeback_keys, &start, &end)) { + s->op.skip = false; + s->writeback = true; + } + + if (bio->bi_rw & REQ_DISCARD) { + if (blk_queue_discard(bdev_get_queue(dc->bdev))) + closure_bio_submit(bio, cl); + + goto skip; + } + + if (s->op.skip) + goto skip; + + if (should_writeback(dc, s->orig_bio)) + s->writeback = true; + + if (!s->writeback) { + s->op.cache_bio = bio_clone_bioset(bio, GFP_NOIO, + dc->disk.bio_split); + if (!s->op.cache_bio) + goto skip; + + trace_bcache_writethrough(s->orig_bio); + closure_bio_submit(bio, cl); + } else { + s->op.cache_bio = bio; + trace_bcache_writeback(s->orig_bio); + bch_writeback_add(dc, bio_sectors(bio)); + } +out: + closure_call(bch_bio_insert, &s->op.cl, cl); + continue_at(cl, cached_dev_write_complete, NULL); +skip: + s->op.skip = true; + s->op.cache_bio = s->orig_bio; + bio_get(s->op.cache_bio); + trace_bcache_write_skip(s->orig_bio); + + closure_bio_submit(bio, cl); + goto out; +} + +static void request_nodata(struct cached_dev *dc, struct search *s) +{ + struct closure *cl = &s->cl; + struct bio *bio = &s->bio.bio; + + if (bio->bi_rw & REQ_DISCARD) { + request_write(dc, s); + return; + } + + if (s->op.flush_journal) + bch_journal_meta(s->op.c, cl); + + closure_bio_submit(bio, cl); + + continue_at(cl, cached_dev_bio_complete, NULL); +} + +/* Cached devices - read & write stuff */ + +int bch_get_congested(struct cache_set *c) +{ + int i; + + if (!c->congested_read_threshold_us && + !c->congested_write_threshold_us) + return 0; + + i = (local_clock_us() - c->congested_last_us) / 1024; + if (i < 0) + return 0; + + i += atomic_read(&c->congested); + if (i >= 0) + return 0; + + i += CONGESTED_MAX; + + return i <= 0 ? 1 : fract_exp_two(i, 6); +} + +static void add_sequential(struct task_struct *t) +{ + ewma_add(t->sequential_io_avg, + t->sequential_io, 8, 0); + + t->sequential_io = 0; +} + +static void check_should_skip(struct cached_dev *dc, struct search *s) +{ + struct hlist_head *iohash(uint64_t k) + { return &dc->io_hash[hash_64(k, RECENT_IO_BITS)]; } + + struct cache_set *c = s->op.c; + struct bio *bio = &s->bio.bio; + + long rand; + int cutoff = bch_get_congested(c); + unsigned mode = cache_mode(dc, bio); + + if (atomic_read(&dc->disk.detaching) || + c->gc_stats.in_use > CUTOFF_CACHE_ADD || + (bio->bi_rw & REQ_DISCARD)) + goto skip; + + if (mode == CACHE_MODE_NONE || + (mode == CACHE_MODE_WRITEAROUND && + (bio->bi_rw & REQ_WRITE))) + goto skip; + + if (bio->bi_sector & (c->sb.block_size - 1) || + bio_sectors(bio) & (c->sb.block_size - 1)) { + pr_debug("skipping unaligned io"); + goto skip; + } + + if (!cutoff) { + cutoff = dc->sequential_cutoff >> 9; + + if (!cutoff) + goto rescale; + + if (mode == CACHE_MODE_WRITEBACK && + (bio->bi_rw & REQ_WRITE) && + (bio->bi_rw & REQ_SYNC)) + goto rescale; + } + + if (dc->sequential_merge) { + struct hlist_node *cursor; + struct io *i; + + spin_lock(&dc->io_lock); + + hlist_for_each_entry(i, cursor, iohash(bio->bi_sector), hash) + if (i->last == bio->bi_sector && + time_before(jiffies, i->jiffies)) + goto found; + + i = list_first_entry(&dc->io_lru, struct io, lru); + + add_sequential(s->task); + i->sequential = 0; +found: + if (i->sequential + bio->bi_size > i->sequential) + i->sequential += bio->bi_size; + + i->last = bio_end(bio); + i->jiffies = jiffies + msecs_to_jiffies(5000); + s->task->sequential_io = i->sequential; + + hlist_del(&i->hash); + hlist_add_head(&i->hash, iohash(i->last)); + list_move_tail(&i->lru, &dc->io_lru); + + spin_unlock(&dc->io_lock); + } else { + s->task->sequential_io = bio->bi_size; + + add_sequential(s->task); + } + + rand = get_random_int(); + cutoff -= bitmap_weight(&rand, BITS_PER_LONG); + + if (cutoff <= (int) (max(s->task->sequential_io, + s->task->sequential_io_avg) >> 9)) + goto skip; + +rescale: + bch_rescale_priorities(c, bio_sectors(bio)); + return; +skip: + bch_mark_sectors_bypassed(s, bio_sectors(bio)); + s->op.skip = true; +} + +static void cached_dev_make_request(struct request_queue *q, struct bio *bio) +{ + struct search *s; + struct bcache_device *d = bio->bi_bdev->bd_disk->private_data; + struct cached_dev *dc = container_of(d, struct cached_dev, disk); + + bio->bi_bdev = dc->bdev; + bio->bi_sector += BDEV_DATA_START; + + if (cached_dev_get(dc)) { + s = search_alloc(bio, d); + trace_bcache_request_start(s, bio); + + if (!bio_has_data(bio)) + request_nodata(dc, s); + else if (bio->bi_rw & REQ_WRITE) + request_write(dc, s); + else + request_read(dc, s); + } else + generic_make_request(bio); +} + +static int cached_dev_ioctl(struct bcache_device *d, fmode_t mode, + unsigned int cmd, unsigned long arg) +{ + struct cached_dev *dc = container_of(d, struct cached_dev, disk); + return __blkdev_driver_ioctl(dc->bdev, mode, cmd, arg); +} + +static int cached_dev_congested(void *data, int bits) +{ + struct bcache_device *d = data; + struct cached_dev *dc = container_of(d, struct cached_dev, disk); + struct request_queue *q = bdev_get_queue(dc->bdev); + int ret = 0; + + if (bdi_congested(&q->backing_dev_info, bits)) + return 1; + + if (cached_dev_get(dc)) { + struct cache *ca; + + for_each_cache(ca, d->c) { + q = bdev_get_queue(ca->bdev); + ret |= bdi_congested(&q->backing_dev_info, bits); + } + + cached_dev_put(dc); + } + + return ret; +} + +void bch_cached_dev_request_init(struct cached_dev *dc) +{ + struct gendisk *g = dc->disk.disk; + + g->queue->make_request_fn = cached_dev_make_request; + g->queue->backing_dev_info.congested_fn = cached_dev_congested; + dc->disk.cache_miss = cached_dev_cache_miss; + dc->disk.ioctl = cached_dev_ioctl; +} + +/* Flash backed devices */ + +static int flash_dev_cache_miss(struct btree *b, struct search *s, + struct bio *bio, unsigned sectors) +{ + /* Zero fill bio */ + + while (bio->bi_idx != bio->bi_vcnt) { + struct bio_vec *bv = bio_iovec(bio); + unsigned j = min(bv->bv_len >> 9, sectors); + + void *p = kmap(bv->bv_page); + memset(p + bv->bv_offset, 0, j << 9); + kunmap(bv->bv_page); + + bv->bv_len -= j << 9; + bv->bv_offset += j << 9; + + if (bv->bv_len) + return 0; + + bio->bi_sector += j; + bio->bi_size -= j << 9; + + bio->bi_idx++; + sectors -= j; + } + + s->op.lookup_done = true; + + return 0; +} + +static void flash_dev_make_request(struct request_queue *q, struct bio *bio) +{ + struct search *s; + struct closure *cl; + struct bcache_device *d = bio->bi_bdev->bd_disk->private_data; + + s = search_alloc(bio, d); + cl = &s->cl; + bio = &s->bio.bio; + + trace_bcache_request_start(s, bio); + + if (bio_has_data(bio) && !(bio->bi_rw & REQ_WRITE)) { + closure_call(btree_read_async, &s->op.cl, cl); + } else if (bio_has_data(bio) || s->op.skip) { + bch_keybuf_check_overlapping(&s->op.c->moving_gc_keys, + &KEY(d->id, bio->bi_sector, 0), + &KEY(d->id, bio_end(bio), 0)); + + s->writeback = true; + s->op.cache_bio = bio; + + closure_call(bch_bio_insert, &s->op.cl, cl); + } else { + /* No data - probably a cache flush */ + if (s->op.flush_journal) + bch_journal_meta(s->op.c, cl); + } + + continue_at(cl, search_free, NULL); +} + +static int flash_dev_ioctl(struct bcache_device *d, fmode_t mode, + unsigned int cmd, unsigned long arg) +{ + return -ENOTTY; +} + +static int flash_dev_congested(void *data, int bits) +{ + struct bcache_device *d = data; + struct request_queue *q; + struct cache *ca; + int ret = 0; + + for_each_cache(ca, d->c) { + q = bdev_get_queue(ca->bdev); + ret |= bdi_congested(&q->backing_dev_info, bits); + } + + return ret; +} + +void bch_flash_dev_request_init(struct bcache_device *d) +{ + struct gendisk *g = d->disk; + + g->queue->make_request_fn = flash_dev_make_request; + g->queue->backing_dev_info.congested_fn = flash_dev_congested; + d->cache_miss = flash_dev_cache_miss; + d->ioctl = flash_dev_ioctl; +} + +void bch_request_exit(void) +{ +#ifdef CONFIG_CGROUP_BCACHE + cgroup_unload_subsys(&bcache_subsys); +#endif + if (bch_search_cache) + kmem_cache_destroy(bch_search_cache); +} + +int __init bch_request_init(void) +{ + bch_search_cache = KMEM_CACHE(search, 0); + if (!bch_search_cache) + return -ENOMEM; + +#ifdef CONFIG_CGROUP_BCACHE + cgroup_load_subsys(&bcache_subsys); + init_bch_cgroup(&bcache_default_cgroup); + + cgroup_add_cftypes(&bcache_subsys, bch_files); +#endif + return 0; +} diff --git a/drivers/md/bcache/request.h b/drivers/md/bcache/request.h new file mode 100644 index 0000000..52b0148 --- /dev/null +++ b/drivers/md/bcache/request.h @@ -0,0 +1,60 @@ +#ifndef _BCACHE_REQUEST_H_ +#define _BCACHE_REQUEST_H_ +#include <linux/cgroup.h> + +struct search { + /* Stack frame for bio_complete */ + struct closure cl; + + struct bcache_device *d; + struct task_struct *task; + + struct bbio bio; + struct bio *orig_bio; + struct bio *cache_miss; + unsigned cache_bio_sectors; + + unsigned recoverable:1; + unsigned unaligned_bvec:1; + + unsigned write:1; + unsigned writeback:1; + + /* IO error returned to s->bio */ + short error; + + /* Anything past op->keys won't get zeroed in do_bio_hook */ + struct btree_op op; +}; + +void bch_cache_read_endio(struct bio *, int); +int bch_get_congested(struct cache_set *); +void bch_bio_insert(struct closure *cl); +void bch_btree_insert_async(struct closure *); +void bch_cache_read_endio(struct bio *, int); + +void bch_open_buckets_free(struct cache_set *); +int bch_open_buckets_alloc(struct cache_set *); + +void bch_cached_dev_request_init(struct cached_dev *dc); +void bch_flash_dev_request_init(struct bcache_device *d); + +extern struct kmem_cache *bch_search_cache, *bch_passthrough_cache; + +struct bch_cgroup { +#ifdef CONFIG_CGROUP_BCACHE + struct cgroup_subsys_state css; +#endif + /* + * We subtract one from the index into bch_cache_modes[], so that + * default == -1; this makes it so the rest match up with d->cache_mode, + * and we use d->cache_mode if cgrp->cache_mode < 0 + */ + short cache_mode; + bool verify; + struct cache_stat_collector stats; +}; + +struct bch_cgroup *bch_bio_to_cgroup(struct bio *bio); + +#endif /* _BCACHE_REQUEST_H_ */ -- 1.7.9.3.327.g2980b -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel