diff options
Diffstat (limited to 'drivers/md/bcache/request.c')
-rw-r--r-- | drivers/md/bcache/request.c | 1411 |
1 files changed, 1411 insertions, 0 deletions
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c new file mode 100644 index 000000000000..e5ff12e52d5b --- /dev/null +++ b/drivers/md/bcache/request.c @@ -0,0 +1,1411 @@ +/* + * Main bcache entry point - handle a read or a write request and decide what to + * do with it; the make_request functions are called by the block layer. + * + * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com> + * Copyright 2012 Google, Inc. + */ + +#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 = bch_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 = bch_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 = bch_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->insert_data_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) +{ + int i; + + spin_lock_init(&c->data_bucket_lock); + + for (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; + unsigned i; + + 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))) { + unsigned watermark = s->op.write_prio + ? WATERMARK_MOVINGGC + : WATERMARK_NONE; + + spin_unlock(&c->data_bucket_lock); + + if (bch_bucket_alloc_set(c, watermark, &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 bch_bucket_alloc_set() took: + */ + if (KEY_PTRS(&alloc.key)) + __bkey_put(c, &alloc.key); + + for (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 (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 (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 (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 bch_insert_data_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 bch_insert_data_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, bch_insert_data_error, bcache_wq); + else + set_closure_fn(cl, NULL, NULL); + } + + bch_bbio_endio(op->c, bio, error, "writing data to cache"); +} + +static void bch_insert_data_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); + } + + do { + unsigned i; + 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 = bch_bio_split(bio, KEY_SIZE(k), GFP_NOIO, split); + if (!n) { + __bkey_put(op->c, k); + continue_at(cl, bch_insert_data_loop, bcache_wq); + } + + n->bi_end_io = bch_insert_data_endio; + n->bi_private = cl; + + if (s->writeback) { + SET_KEY_DIRTY(k, true); + + for (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->insert_data_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->insert_data_done = true; + bio_put(bio); + + if (!bch_keylist_empty(&op->keys)) + continue_at(cl, bch_journal, bcache_wq); + else + closure_return(cl); + } +} + +/** + * bch_insert_data - stick some data in the cache + * + * This is the starting point for any data to end up in a cache device; it could + * be from a normal write, or a writeback write, or a write to a flash only + * volume - it's also used by the moving garbage collector to compact data in + * mostly empty buckets. + * + * It first writes the data to the cache, creating a list of keys to be inserted + * (if the data had to be fragmented there will be multiple keys); after the + * data is written it calls bch_journal, and after the keys have been added to + * the next journal write they're inserted into the btree. + * + * It inserts the data in op->cache_bio; bi_sector is used for the key offset, + * and op->inode is used for the key inode. + * + * If op->skip is true, instead of inserting the data it invalidates the region + * of the cache represented by op->cache_bio and op->inode. + */ +void bch_insert_data(struct closure *cl) +{ + struct btree_op *op = container_of(cl, struct btree_op, cl); + + bch_keylist_init(&op->keys); + bio_get(op->cache_bio); + bch_insert_data_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->insert_data_done = true; + } + + if (op->insert_data_done) { + bch_keylist_free(&op->keys); + closure_return(cl); + } else + continue_at(cl, bch_insert_data_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) { + int cpu, rw = bio_data_dir(s->orig_bio); + unsigned long duration = jiffies - s->start_time; + + cpu = part_stat_lock(); + part_round_stats(cpu, &s->d->disk->part0); + part_stat_add(cpu, &s->d->disk->part0, ticks[rw], duration); + part_stat_unlock(); + + 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; + s->start_time = jiffies; + 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->op.insert_collision) + bch_mark_cache_miss_collision(s); + + 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, s->d); + } + + 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; + bch_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; + } + + bio_put(s->cache_miss); + s->cache_miss = NULL; + } + + if (verify(dc, &s->bio.bio) && s->recoverable) + bch_data_verify(s); + + bio_complete(s); + + if (s->op.cache_bio && + !test_bit(CACHE_SET_STOPPING, &s->op.c->flags)) { + s->op.type = BTREE_REPLACE; + closure_call(&s->op.cl, bch_insert_data, NULL, 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); + + 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 = bch_bio_split(bio, sectors, GFP_NOIO, s->d->bio_split); + if (!miss) + return -EAGAIN; + + if (miss == bio) + s->op.lookup_done = true; + + miss->bi_end_io = request_endio; + miss->bi_private = &s->cl; + + 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 = min(dc->readahead >> 9, + sectors - bio_sectors(miss)); + + 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; + + bch_bio_map(s->op.cache_bio, NULL); + if (bch_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, s->d); + + return ret; +out_put: + bio_put(s->op.cache_bio); + s->op.cache_bio = NULL; +out_submit: + closure_bio_submit(miss, &s->cl, s->d); + 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(&s->op.cl, btree_read_async, NULL, 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) + 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); + + trace_bcache_writethrough(s->orig_bio); + closure_bio_submit(bio, cl, s->d); + } else { + s->op.cache_bio = bio; + trace_bcache_writeback(s->orig_bio); + bch_writeback_add(dc, bio_sectors(bio)); + } +out: + closure_call(&s->op.cl, bch_insert_data, NULL, 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); + + if ((bio->bi_rw & REQ_DISCARD) && + !blk_queue_discard(bdev_get_queue(dc->bdev))) + goto out; + + closure_bio_submit(bio, cl, s->d); + 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, s->d); + + 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 struct hlist_head *iohash(struct cached_dev *dc, uint64_t k) +{ + return &dc->io_hash[hash_64(k, RECENT_IO_BITS)]; +} + +static void check_should_skip(struct cached_dev *dc, struct search *s) +{ + 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 io *i; + + spin_lock(&dc->io_lock); + + hlist_for_each_entry(i, iohash(dc, 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(dc, 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 < |