diff options
Diffstat (limited to 'drivers/md/bcache/request.c')
| -rw-r--r-- | drivers/md/bcache/request.c | 1345 |
1 files changed, 1345 insertions, 0 deletions
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c new file mode 100644 index 000000000..3427555b0 --- /dev/null +++ b/drivers/md/bcache/request.c @@ -0,0 +1,1345 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * 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 "writeback.h" + +#include <linux/module.h> +#include <linux/hash.h> +#include <linux/random.h> +#include <linux/backing-dev.h> + +#include <trace/events/bcache.h> + +#define CUTOFF_CACHE_ADD 95 +#define CUTOFF_CACHE_READA 90 + +struct kmem_cache *bch_search_cache; + +static void bch_data_insert_start(struct closure *cl); + +static unsigned int cache_mode(struct cached_dev *dc) +{ + return BDEV_CACHE_MODE(&dc->sb); +} + +static bool verify(struct cached_dev *dc) +{ + return dc->verify; +} + +static void bio_csum(struct bio *bio, struct bkey *k) +{ + struct bio_vec bv; + struct bvec_iter iter; + uint64_t csum = 0; + + bio_for_each_segment(bv, bio, iter) { + void *d = bvec_kmap_local(&bv); + + csum = crc64_be(csum, d, bv.bv_len); + kunmap_local(d); + } + + k->ptr[KEY_PTRS(k)] = csum & (~0ULL >> 1); +} + +/* Insert data into cache */ + +static void bch_data_insert_keys(struct closure *cl) +{ + struct data_insert_op *op = container_of(cl, struct data_insert_op, cl); + atomic_t *journal_ref = NULL; + struct bkey *replace_key = op->replace ? &op->replace_key : NULL; + int ret; + + if (!op->replace) + journal_ref = bch_journal(op->c, &op->insert_keys, + op->flush_journal ? cl : NULL); + + ret = bch_btree_insert(op->c, &op->insert_keys, + journal_ref, replace_key); + if (ret == -ESRCH) { + op->replace_collision = true; + } else if (ret) { + op->status = BLK_STS_RESOURCE; + op->insert_data_done = true; + } + + if (journal_ref) + atomic_dec_bug(journal_ref); + + if (!op->insert_data_done) { + continue_at(cl, bch_data_insert_start, op->wq); + return; + } + + bch_keylist_free(&op->insert_keys); + closure_return(cl); +} + +static int bch_keylist_realloc(struct keylist *l, unsigned int u64s, + struct cache_set *c) +{ + size_t oldsize = bch_keylist_nkeys(l); + size_t newsize = oldsize + u64s; + + /* + * The journalling code doesn't handle the case where the keys to insert + * is bigger than an empty write: If we just return -ENOMEM here, + * bch_data_insert_keys() will insert the keys created so far + * and finish the rest when the keylist is empty. + */ + if (newsize * sizeof(uint64_t) > block_bytes(c->cache) - sizeof(struct jset)) + return -ENOMEM; + + return __bch_keylist_realloc(l, u64s); +} + +static void bch_data_invalidate(struct closure *cl) +{ + struct data_insert_op *op = container_of(cl, struct data_insert_op, cl); + struct bio *bio = op->bio; + + pr_debug("invalidating %i sectors from %llu\n", + bio_sectors(bio), (uint64_t) bio->bi_iter.bi_sector); + + while (bio_sectors(bio)) { + unsigned int sectors = min(bio_sectors(bio), + 1U << (KEY_SIZE_BITS - 1)); + + if (bch_keylist_realloc(&op->insert_keys, 2, op->c)) + goto out; + + bio->bi_iter.bi_sector += sectors; + bio->bi_iter.bi_size -= sectors << 9; + + bch_keylist_add(&op->insert_keys, + &KEY(op->inode, + bio->bi_iter.bi_sector, + sectors)); + } + + op->insert_data_done = true; + /* get in bch_data_insert() */ + bio_put(bio); +out: + continue_at(cl, bch_data_insert_keys, op->wq); +} + +static void bch_data_insert_error(struct closure *cl) +{ + struct data_insert_op *op = container_of(cl, struct data_insert_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 successfully 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->insert_keys.keys, *dst = op->insert_keys.keys; + + while (src != op->insert_keys.top) { + struct bkey *n = bkey_next(src); + + SET_KEY_PTRS(src, 0); + memmove(dst, src, bkey_bytes(src)); + + dst = bkey_next(dst); + src = n; + } + + op->insert_keys.top = dst; + + bch_data_insert_keys(cl); +} + +static void bch_data_insert_endio(struct bio *bio) +{ + struct closure *cl = bio->bi_private; + struct data_insert_op *op = container_of(cl, struct data_insert_op, cl); + + if (bio->bi_status) { + /* TODO: We could try to recover from this. */ + if (op->writeback) + op->status = bio->bi_status; + else if (!op->replace) + set_closure_fn(cl, bch_data_insert_error, op->wq); + else + set_closure_fn(cl, NULL, NULL); + } + + bch_bbio_endio(op->c, bio, bio->bi_status, "writing data to cache"); +} + +static void bch_data_insert_start(struct closure *cl) +{ + struct data_insert_op *op = container_of(cl, struct data_insert_op, cl); + struct bio *bio = op->bio, *n; + + if (op->bypass) + return bch_data_invalidate(cl); + + if (atomic_sub_return(bio_sectors(bio), &op->c->sectors_to_gc) < 0) + wake_up_gc(op->c); + + /* + * Journal writes are marked REQ_PREFLUSH; if the original write was a + * flush, it'll wait on the journal write. + */ + bio->bi_opf &= ~(REQ_PREFLUSH|REQ_FUA); + + do { + unsigned int i; + struct bkey *k; + struct bio_set *split = &op->c->bio_split; + + /* 1 for the device pointer and 1 for the chksum */ + if (bch_keylist_realloc(&op->insert_keys, + 3 + (op->csum ? 1 : 0), + op->c)) { + continue_at(cl, bch_data_insert_keys, op->wq); + return; + } + + k = op->insert_keys.top; + bkey_init(k); + SET_KEY_INODE(k, op->inode); + SET_KEY_OFFSET(k, bio->bi_iter.bi_sector); + + if (!bch_alloc_sectors(op->c, k, bio_sectors(bio), + op->write_point, op->write_prio, + op->writeback)) + goto err; + + n = bio_next_split(bio, KEY_SIZE(k), GFP_NOIO, split); + + n->bi_end_io = bch_data_insert_endio; + n->bi_private = cl; + + if (op->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); + + trace_bcache_cache_insert(k); + bch_keylist_push(&op->insert_keys); + + bio_set_op_attrs(n, REQ_OP_WRITE, 0); + bch_submit_bbio(n, op->c, k, 0); + } while (n != bio); + + op->insert_data_done = true; + continue_at(cl, bch_data_insert_keys, op->wq); + return; +err: + /* bch_alloc_sectors() blocks if s->writeback = true */ + BUG_ON(op->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 (!op->replace) { + /* + * 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->bypass = true; + return bch_data_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->insert_keys)) + continue_at(cl, bch_data_insert_keys, op->wq); + else + closure_return(cl); + } +} + +/** + * bch_data_insert - stick some data in the cache + * @cl: closure pointer. + * + * 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->bio; bi_sector is used for the key offset, + * and op->inode is used for the key inode. + * + * If op->bypass is true, instead of inserting the data it invalidates the + * region of the cache represented by op->bio and op->inode. + */ +void bch_data_insert(struct closure *cl) +{ + struct data_insert_op *op = container_of(cl, struct data_insert_op, cl); + + trace_bcache_write(op->c, op->inode, op->bio, + op->writeback, op->bypass); + + bch_keylist_init(&op->insert_keys); + bio_get(op->bio); + bch_data_insert_start(cl); +} + +/* + * Congested? Return 0 (not congested) or the limit (in sectors) + * beyond which we should bypass the cache due to congestion. + */ +unsigned int bch_get_congested(const 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; + + if (i > 0) + i = fract_exp_two(i, 6); + + i -= hweight32(get_random_u32()); + + return i > 0 ? i : 1; +} + +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 bool check_should_bypass(struct cached_dev *dc, struct bio *bio) +{ + struct cache_set *c = dc->disk.c; + unsigned int mode = cache_mode(dc); + unsigned int sectors, congested; + struct task_struct *task = current; + struct io *i; + + if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) || + c->gc_stats.in_use > CUTOFF_CACHE_ADD || + (bio_op(bio) == REQ_OP_DISCARD)) + goto skip; + + if (mode == CACHE_MODE_NONE || + (mode == CACHE_MODE_WRITEAROUND && + op_is_write(bio_op(bio)))) + goto skip; + + /* + * If the bio is for read-ahead or background IO, bypass it or + * not depends on the following situations, + * - If the IO is for meta data, always cache it and no bypass + * - If the IO is not meta data, check dc->cache_reada_policy, + * BCH_CACHE_READA_ALL: cache it and not bypass + * BCH_CACHE_READA_META_ONLY: not cache it and bypass + * That is, read-ahead request for metadata always get cached + * (eg, for gfs2 or xfs). + */ + if ((bio->bi_opf & (REQ_RAHEAD|REQ_BACKGROUND))) { + if (!(bio->bi_opf & (REQ_META|REQ_PRIO)) && + (dc->cache_readahead_policy != BCH_CACHE_READA_ALL)) + goto skip; + } + + if (bio->bi_iter.bi_sector & (c->cache->sb.block_size - 1) || + bio_sectors(bio) & (c->cache->sb.block_size - 1)) { + pr_debug("skipping unaligned io\n"); + goto skip; + } + + if (bypass_torture_test(dc)) { + if (prandom_u32_max(4) == 3) + goto skip; + else + goto rescale; + } + + congested = bch_get_congested(c); + if (!congested && !dc->sequential_cutoff) + goto rescale; + + spin_lock(&dc->io_lock); + + hlist_for_each_entry(i, iohash(dc, bio->bi_iter.bi_sector), hash) + if (i->last == bio->bi_iter.bi_sector && + time_before(jiffies, i->jiffies)) + goto found; + + i = list_first_entry(&dc->io_lru, struct io, lru); + + add_sequential(task); + i->sequential = 0; +found: + if (i->sequential + bio->bi_iter.bi_size > i->sequential) + i->sequential += bio->bi_iter.bi_size; + + i->last = bio_end_sector(bio); + i->jiffies = jiffies + msecs_to_jiffies(5000); + 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); + + sectors = max(task->sequential_io, + task->sequential_io_avg) >> 9; + + if (dc->sequential_cutoff && + sectors >= dc->sequential_cutoff >> 9) { + trace_bcache_bypass_sequential(bio); + goto skip; + } + + if (congested && sectors >= congested) { + trace_bcache_bypass_congested(bio); + goto skip; + } + +rescale: + bch_rescale_priorities(c, bio_sectors(bio)); + return false; +skip: + bch_mark_sectors_bypassed(c, dc, bio_sectors(bio)); + return true; +} + +/* Cache lookup */ + +struct search { + /* Stack frame for bio_complete */ + struct closure cl; + + struct bbio bio; + struct bio *orig_bio; + struct bio *cache_miss; + struct bcache_device *d; + + unsigned int insert_bio_sectors; + unsigned int recoverable:1; + unsigned int write:1; + unsigned int read_dirty_data:1; + unsigned int cache_missed:1; + + struct block_device *orig_bdev; + unsigned long start_time; + + struct btree_op op; + struct data_insert_op iop; +}; + +static void bch_cache_read_endio(struct bio *bio) +{ + 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 (bio->bi_status) + s->iop.status = bio->bi_status; + else if (!KEY_DIRTY(&b->key) && + ptr_stale(s->iop.c, &b->key, 0)) { + atomic_long_inc(&s->iop.c->cache_read_races); + s->iop.status = BLK_STS_IOERR; + } + + bch_bbio_endio(s->iop.c, bio, bio->bi_status, "reading from cache"); +} + +/* + * Read from a single key, handling the initial cache miss if the key starts in + * the middle of the bio + */ +static int cache_lookup_fn(struct btree_op *op, struct btree *b, struct bkey *k) +{ + struct search *s = container_of(op, struct search, op); + struct bio *n, *bio = &s->bio.bio; + struct bkey *bio_key; + unsigned int ptr; + + if (bkey_cmp(k, &KEY(s->iop.inode, bio->bi_iter.bi_sector, 0)) <= 0) + return MAP_CONTINUE; + + if (KEY_INODE(k) != s->iop.inode || + KEY_START(k) > bio->bi_iter.bi_sector) { + unsigned int bio_sectors = bio_sectors(bio); + unsigned int sectors = KEY_INODE(k) == s->iop.inode + ? min_t(uint64_t, INT_MAX, + KEY_START(k) - bio->bi_iter.bi_sector) + : INT_MAX; + int ret = s->d->cache_miss(b, s, bio, sectors); + + if (ret != MAP_CONTINUE) + return ret; + + /* if this was a complete miss we shouldn't get here */ + BUG_ON(bio_sectors <= sectors); + } + + if (!KEY_SIZE(k)) + return MAP_CONTINUE; + + /* XXX: figure out best pointer - for multiple cache devices */ + ptr = 0; + + PTR_BUCKET(b->c, k, ptr)->prio = INITIAL_PRIO; + + if (KEY_DIRTY(k)) + s->read_dirty_data = true; + + n = bio_next_split(bio, min_t(uint64_t, INT_MAX, + KEY_OFFSET(k) - bio->bi_iter.bi_sector), + GFP_NOIO, &s->d->bio_split); + + bio_key = &container_of(n, struct bbio, bio)->key; + bch_bkey_copy_single_ptr(bio_key, k, ptr); + + bch_cut_front(&KEY(s->iop.inode, n->bi_iter.bi_sector, 0), bio_key); + bch_cut_back(&KEY(s->iop.inode, bio_end_sector(n), 0), bio_key); + + n->bi_end_io = bch_cache_read_endio; + n->bi_private = &s->cl; + + /* + * The bucket we're reading from might be reused while our bio + * is in flight, and we could then end up reading the wrong + * data. + * + * We guard against this by checking (in cache_read_endio()) if + * the pointer is stale again; if so, we treat it as an error + * and reread from the backing device (but we don't pass that + * error up anywhere). + */ + + __bch_submit_bbio(n, b->c); + return n == bio ? MAP_DONE : MAP_CONTINUE; +} + +static void cache_lookup(struct closure *cl) +{ + struct search *s = container_of(cl, struct search, iop.cl); + struct bio *bio = &s->bio.bio; + struct cached_dev *dc; + int ret; + + bch_btree_op_init(&s->op, -1); + + ret = bch_btree_map_keys(&s->op, s->iop.c, + &KEY(s->iop.inode, bio->bi_iter.bi_sector, 0), + cache_lookup_fn, MAP_END_KEY); + if (ret == -EAGAIN) { + continue_at(cl, cache_lookup, bcache_wq); + return; + } + + /* + * We might meet err when searching the btree, If that happens, we will + * get negative ret, in this scenario we should not recover data from + * backing device (when cache device is dirty) because we don't know + * whether bkeys the read request covered are all clean. + * + * And after that happened, s->iop.status is still its initial value + * before we submit s->bio.bio + */ + if (ret < 0) { + BUG_ON(ret == -EINTR); + if (s->d && s->d->c && + !UUID_FLASH_ONLY(&s->d->c->uuids[s->d->id])) { + dc = container_of(s->d, struct cached_dev, disk); + if (dc && atomic_read(&dc->has_dirty)) + s->recoverable = false; + } + if (!s->iop.status) + s->iop.status = BLK_STS_IOERR; + } + + closure_return(cl); +} + +/* Common code for the make_request functions */ + +static void request_endio(struct bio *bio) +{ + struct closure *cl = bio->bi_private; + + if (bio->bi_status) { + struct search *s = container_of(cl, struct search, cl); + + s->iop.status = bio->bi_status; + /* Only cache read errors are recoverable */ + s->recoverable = false; + } + + bio_put(bio); + closure_put(cl); +} + +static void backing_request_endio(struct bio *bio) +{ + struct closure *cl = bio->bi_private; + + if (bio->bi_status) { + struct search *s = container_of(cl, struct search, cl); + struct cached_dev *dc = container_of(s->d, + struct cached_dev, disk); + /* + * If a bio has REQ_PREFLUSH for writeback mode, it is + * speically assembled in cached_dev_write() for a non-zero + * write request which has REQ_PREFLUSH. we don't set + * s->iop.status by this failure, the status will be decided + * by result of bch_data_insert() operation. + */ + if (unlikely(s->iop.writeback && + bio->bi_opf & REQ_PREFLUSH)) { + pr_err("Can't flush %pg: returned bi_status %i\n", + dc->bdev, bio->bi_status); + } else { + /* set to orig_bio->bi_status in bio_complete() */ + s->iop.status = bio->bi_status; + } + s->recoverable = false; + /* should count I/O error for backing device here */ + bch_count_backing_io_errors(dc, bio); + } + + bio_put(bio); + closure_put(cl); +} + +static void bio_complete(struct search *s) +{ + if (s->orig_bio) { + /* Count on bcache device */ + bio_end_io_acct_remapped(s->orig_bio, s->start_time, + s->orig_bdev); + trace_bcache_request_end(s->d, s->orig_bio); + s->orig_bio->bi_status = s->iop.status; + bio_endio(s->orig_bio); + s->orig_bio = NULL; + } +} + +static void do_bio_hook(struct search *s, + struct bio *orig_bio, + bio_end_io_t *end_io_fn) +{ + struct bio *bio = &s->bio.bio; + + bio_init_clone(orig_bio->bi_bdev, bio, orig_bio, GFP_NOIO); + /* + * bi_end_io can be set separately somewhere else, e.g. the + * variants in, + * - cache_bio->bi_end_io from cached_dev_cache_miss() + * - n->bi_end_io from cache_lookup_fn() + */ + bio->bi_end_io = end_io_fn; + bio->bi_private = &s->cl; + + bio_cnt_set(bio, 3); +} + +static void search_free(struct closure *cl) +{ + struct search *s = container_of(cl, struct search, cl); + + atomic_dec(&s->iop.c->search_inflight); + + if (s->iop.bio) + bio_put(s->iop.bio); + + bio_complete(s); + closure_debug_destroy(cl); + mempool_free(s, &s->iop.c->search); +} + +static inline struct search *search_alloc(struct bio *bio, + struct bcache_device *d, struct block_device *orig_bdev, + unsigned long start_time) +{ + struct search *s; + + s = mempool_alloc(&d->c->search, GFP_NOIO); + + closure_init(&s->cl, NULL); + do_bio_hook(s, bio, request_endio); + atomic_inc(&d->c->search_inflight); + + s->orig_bio = bio; + s->cache_miss = NULL; + s->cache_missed = 0; + s->d = d; + s->recoverable = 1; + s->write = op_is_write(bio_op(bio)); + s->read_dirty_data = 0; + /* Count on the bcache device */ + s->orig_bdev = orig_bdev; + s->start_time = start_time; + s->iop.c = d->c; + s->iop.bio = NULL; + s->iop.inode = d->id; + s->iop.write_point = hash_long((unsigned long) current, 16); + s->iop.write_prio = 0; + s->iop.status = 0; + s->iop.flags = 0; + s->iop.flush_journal = op_is_flush(bio->bi_opf); + s->iop.wq = bcache_wq; + + return s; +} + +/* 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); + + cached_dev_put(dc); + search_free(cl); +} + +/* Process reads */ + +static void cached_dev_read_error_done(struct closure *cl) +{ + struct search *s = container_of(cl, struct search, cl); + + if (s->iop.replace_collision) + bch_mark_cache_miss_collision(s->iop.c, s->d); + + if (s->iop.bio) + bio_free_pages(s->iop.bio); + + cached_dev_bio_complete(cl); +} + +static void cached_dev_read_error(struct closure *cl) +{ + struct search *s = container_of(cl, struct search, cl); + struct bio *bio = &s->bio.bio; + + /* + * If read request hit dirty data (s->read_dirty_data is true), + * then recovery a failed read request from cached device may + * get a stale data back. So read failure recovery is only + * permitted when read request hit clean data in cache device, + * or when cache read race happened. + */ + if (s->recoverable && !s->read_dirty_data) { + /* Retry from the backing device: */ + trace_bcache_read_retry(s->orig_bio); + + s->iop.status = 0; + do_bio_hook(s, s->orig_bio, backing_request_endio); + + /* XXX: invalidate cache */ + + /* I/O request sent to backing device */ + closure_bio_submit(s->iop.c, bio, cl); + } + + continue_at(cl, cached_dev_read_error_done, NULL); +} + +static void cached_dev_cache_miss_done(struct closure *cl) +{ + struct search *s = container_of(cl, struct search, cl); + struct bcache_device *d = s->d; + + if (s->iop.replace_collision) + bch_mark_cache_miss_collision(s->iop.c, s->d); + + if (s->iop.bio) + bio_free_pages(s->iop.bio); + + cached_dev_bio_complete(cl); + closure_put(&d->cl); +} + +static void cached_dev_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); + + /* + * 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->iop.bio) { + bio_reset(s->iop.bio, s->cache_miss->bi_bdev, REQ_OP_READ); + s->iop.bio->bi_iter.bi_sector = + s->cache_miss->bi_iter.bi_sector; + s->iop.bio->bi_iter.bi_size = s->insert_bio_sectors << 9; + bio_clone_blkg_association(s->iop.bio, s->cache_miss); + bch_bio_map(s->iop.bio, NULL); + + bio_copy_data(s->cache_miss, s->iop.bio); + + bio_put(s->cache_miss); + s->cache_miss = NULL; + } + + if (verify(dc) && s->recoverable && !s->read_dirty_data) + bch_data_verify(dc, s->orig_bio); + + closure_get(&dc->disk.cl); + bio_complete(s); + + if (s->iop.bio && + !test_bit(CACHE_SET_STOPPING, &s->iop.c->flags)) { + BUG_ON(!s->iop.replace); + closure_call(&s->iop.cl, bch_data_insert, NULL, cl); + } + + continue_at(cl, cached_dev_cache_miss_done, NULL); +} + +static void cached_dev_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->iop.c, s->d, + !s->cache_missed, s->iop.bypass); + trace_bcache_read(s->orig_bio, !s->cache_missed, s->iop.bypass); + + if (s->iop.status) + continue_at_nobarrier(cl, cached_dev_read_error, bcache_wq); + else if (s->iop.bio || verify(dc)) + continue_at_nobarrier(cl, cached_dev_read_done, bcache_wq); + else + continue_at_nobarrier(cl, cached_dev_bio_complete, NULL); +} + +static int cached_dev_cache_miss(struct btree *b, struct search *s, + struct bio *bio, unsigned int sectors) +{ + int ret = MAP_CONTINUE; + struct cached_dev *dc = container_of(s->d, struct cached_dev, disk); + struct bio *miss, *cache_bio; + unsigned int size_limit; + + s->cache_missed = 1; + + if (s->cache_miss || s->iop.bypass) { + miss = bio_next_split(bio, sectors, GFP_NOIO, &s->d->bio_split); + ret = miss == bio ? MAP_DONE : MAP_CONTINUE; + goto out_submit; + } + + /* Limitation for valid replace key size and cache_bio bvecs number */ + size_limit = min_t(unsigned int, BIO_MAX_VECS * PAGE_SECTORS, + (1 << KEY_SIZE_BITS) - 1); + s->insert_bio_sectors = min3(size_limit, sectors, bio_sectors(bio)); + + s->iop.replace_key = KEY(s->iop.inode, + bio->bi_iter.bi_sector + s->insert_bio_sectors, + s->insert_bio_sectors); + + ret = bch_btree_insert_check_key(b, &s->op, &s->iop.replace_key); + if (ret) + return ret; + + s->iop.replace = true; + + miss = bio_next_split(bio, s->insert_bio_sectors, GFP_NOIO, + &s->d->bio_split); + + /* btree_search_recurse()'s btree iterator is no good anymore */ + ret = miss == bio ? MAP_DONE : -EINTR; + + cache_bio = bio_alloc_bioset(miss->bi_bdev, + DIV_ROUND_UP(s->insert_bio_sectors, PAGE_SECTORS), + 0, GFP_NOWAIT, &dc->disk.bio_split); + if (!cache_bio) + goto out_submit; + + cache_bio->bi_iter.bi_sector = miss->bi_iter.bi_sector; + cache_bio->bi_iter.bi_size = s->insert_bio_sectors << 9; + + cache_bio->bi_end_io = backing_request_endio; + cache_bio->bi_private = &s->cl; + + bch_bio_map(cache_bio, NULL); + if (bch_bio_alloc_pages(cache_bio, __GFP_NOWARN|GFP_NOIO)) + goto out_put; + + s->cache_miss = miss; + s->iop.bio = cache_bio; + bio_get(cache_bio); + /* I/O request sent to backing device */ + closure_bio_submit(s->iop.c, cache_bio, &s->cl); + + return ret; +out_put: + bio_put(cache_bio); +out_submit: + miss->bi_end_io = backing_request_endio; + miss->bi_private = &s->cl; + /* I/O request sent to backing device */ + closure_bio_submit(s->iop.c, miss, &s->cl); + return ret; +} + +static void cached_dev_read(struct cached_dev *dc, struct search *s) +{ + struct closure *cl = &s->cl; + + closure_call(&s->iop.cl, cache_lookup, NULL, cl); + continue_at(cl, cached_dev_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 void cached_dev_write(struct cached_dev *dc, struct search *s) +{ + struct closure *cl = &s->cl; + struct bio *bio = &s->bio.bio; + struct bkey start = KEY(dc->disk.id, bio->bi_iter.bi_sector, 0); + struct bkey end = KEY(dc->disk.id, bio_end_sector(bio), 0); + + bch_keybuf_check_overlapping(&s->iop.c->moving_gc_keys, &start, &end); + + down_read_non_owner(&dc->writeback_lock); + if (bch_keybuf_check_overlapping(&dc->writeback_keys, &start, &end)) { + /* + * We overlap with some dirty data undergoing background + * writeback, force this write to writeback + */ + s->iop.bypass = false; + s->iop.writeback = true; + } + + /* + * Discards aren't _required_ to do anything, so skipping if + * check_overlapping returned true is ok + * + * But check_overlapping drops dirty keys for which io hasn't started, + * so we still want to call it. + */ + if (bio_op(bio) == REQ_OP_DISCARD) + s->iop.bypass = true; + + if (should_writeback(dc, s->orig_bio, + cache_mode(dc), + s->iop.bypass)) { + s->iop.bypass = false; + s->iop.writeback = true; + } + + if (s->iop.bypass) { + s->iop.bio = s->orig_bio; + bio_get(s->iop.bio); + + if (bio_op(bio) == REQ_OP_DISCARD && + !bdev_max_discard_sectors(dc->bdev)) + goto insert_data; + + /* I/O request sent to backing device */ + bio->bi_end_io = backing_request_endio; + closure_bio_submit(s->iop.c, bio, cl); + + } else if (s->iop.writeback) { + bch_writeback_add(dc); + s->iop.bio = bio; + + if (bio->bi_opf & REQ_PREFLUSH) { + /* + * Also need to send a flush to the backing + * device. + */ + struct bio *flush; + + flush = bio_alloc_bioset(bio->bi_bdev, 0, + REQ_OP_WRITE | REQ_PREFLUSH, + GFP_NOIO, &dc->disk.bio_split); + if (!flush) { + s->iop.status = BLK_STS_RESOURCE; + goto insert_data; + } + flush->bi_end_io = backing_request_endio; + flush->bi_private = cl; + /* I/O request sent to backing device */ + closure_bio_submit(s->iop.c, flush, cl); + } + } else { + s->iop.bio = bio_alloc_clone(bio->bi_bdev, bio, GFP_NOIO, + &dc->disk.bio_split); + /* I/O request sent to backing device */ + bio->bi_end_io = backing_request_endio; + closure_bio_submit(s->iop.c, bio, cl); + } + +insert_data: + closure_call(&s->iop.cl, bch_data_insert, NULL, cl); + continue_at(cl, cached_dev_write_complete, NULL); +} + +static void cached_dev_nodata(struct closure *cl) +{ + struct search *s = container_of(cl, struct search, cl); + struct bio *bio = &s->bio.bio; + + if (s->iop.flush_journal) + bch_journal_meta(s->iop.c, cl); + + /* If it's a flush, we send the flush to the backing device too */ + bio->bi_end_io = backing_request_endio; + closure_bio_submit(s->iop.c, bio, cl); + + continue_at(cl, cached_dev_bio_complete, NULL); +} + +struct detached_dev_io_private { + struct bcache_device *d; + unsigned long start_time; + bio_end_io_t *bi_end_io; + void *bi_private; + struct block_device *orig_bdev; +}; + +static void detached_dev_end_io(struct bio *bio) +{ + struct detached_dev_io_private *ddip; + + ddip = bio->bi_private; + bio->bi_end_io = ddip->bi_end_io; + bio->bi_private = ddip->bi_private; + + /* Count on the bcache device */ + bio_end_io_acct_remapped(bio, ddip->start_time, ddip->orig_bdev); + + if (bio->bi_status) { + struct cached_dev *dc = container_of(ddip->d, + struct cached_dev, disk); + /* should count I/O error for backing device here */ + bch_count_backing_io_errors(dc, bio); + } + + kfree(ddip); + bio->bi_end_io(bio); +} + +static void detached_dev_do_request(struct bcache_device *d, struct bio *bio, + struct block_device *orig_bdev, unsigned long start_time) +{ + struct detached_dev_io_private *ddip; + struct cached_dev *dc = container_of(d, struct cached_dev, disk); + + /* + * no need to call closure_get(&dc->disk.cl), + * because upper layer had already opened bcache device, + * which would call closure_get(&dc->disk.cl) + */ + ddip = kzalloc(sizeof(struct detached_dev_io_private), GFP_NOIO); + if (!ddip) { + bio->bi_status = BLK_STS_RESOURCE; + bio->bi_end_io(bio); + return; + } + + ddip->d = d; + /* Count on the bcache device */ + ddip->orig_bdev = orig_bdev; + ddip->start_time = start_time; + ddip->bi_end_io = bio->bi_end_io; + ddip->bi_private = bio->bi_private; + bio->bi_end_io = detached_dev_end_io; + bio->bi_private = ddip; + + if ((bio_op(bio) == REQ_OP_DISCARD) && + !bdev_max_discard_sectors(dc->bdev)) + bio->bi_end_io(bio); + else + submit_bio_noacct(bio); +} + +static void quit_max_writeback_rate(struct cache_set *c, + struct cached_dev *this_dc) +{ + int i; + struct bcache_device *d; + struct cached_dev *dc; + + /* + * mutex bch_register_lock may compete with other parallel requesters, + * or attach/detach operations on other backing device. Waiting to + * the mutex lock may increase I/O request latency for seconds or more. + * To avoid such situation, if mutext_trylock() failed, only writeback + * rate of current cached device is set to 1, and __update_write_back() + * will decide writeback rate of other cached devices (remember now + * c->idle_counter is 0 already). + */ + if (mutex_trylock(&bch_register_lock)) { + for (i = 0; i < c->devices_max_used; i++) { + if (!c->devices[i]) + continue; + + if (UUID_FLASH_ONLY(&c->uuids[i])) + continue; + + d = c->devices[i]; + dc = container_of(d, struct cached_dev, disk); + /* + * set writeback rate to default minimum value, + * then let update_writeback_rate() to decide the + * upcoming rate. + */ + atomic_long_set(&dc->writeback_rate.rate, 1); + } + mutex_unlock(&bch_register_lock); + } else + atomic_long_set(&this_dc->writeback_rate.rate, 1); +} + +/* Cached devices - read & write stuff */ + +void cached_dev_submit_bio(struct bio *bio) +{ + struct search *s; + struct block_device *orig_bdev = bio->bi_bdev; + struct bcache_device *d = orig_bdev->bd_disk->private_data; + struct cached_dev *dc = container_of(d, struct cached_dev, disk); + unsigned long start_time; + int rw = bio_data_dir(bio); + + if (unlikely((d->c && test_bit(CACHE_SET_IO_DISABLE, &d->c->flags)) || + dc->io_disable)) { + bio->bi_status = BLK_STS_IOERR; + bio_endio(bio); + return; + } + + if (likely(d->c)) { + if (atomic_read(&d->c->idle_counter)) + atomic_set(&d->c->idle_counter, 0); + /* + * If at_max_writeback_rate of cache set is true and new I/O + * comes, quit max writeback rate of all cached devices + * attached to this cache set, and set at_max_writeback_rate + * to false. + */ + if (unlikely(atomic_read(&d->c->at_max_writeback_rate) == 1)) { + atomic_set(&d->c->at_max_writeback_rate, 0); + quit_max_writeback_rate(d->c, dc); + } + } + + start_time = bio_start_io_acct(bio); + + bio_set_dev(bio, dc->bdev); + bio->bi_iter.bi_sector += dc->sb.data_offset; + + if (cached_dev_get(dc)) { + s = search_alloc(bio, d, orig_bdev, start_time); + trace_bcache_request_start(s->d, bio); + + if (!bio->bi_iter.bi_size) { + /* + * can't call bch_journal_meta from under + * submit_bio_noacct + */ + continue_at_nobarrier(&s->cl, + cached_dev_nodata, + bcache_wq); + } else { + s->iop.bypass = check_should_bypass(dc, bio); + + if (rw) + cached_dev_write(dc, s); + else + cached_dev_read(dc, s); + } + } else + /* I/O request sent to backing device */ + detached_dev_do_request(d, bio, orig_bdev, start_time); +} + +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); + + if (dc->io_disable) + return -EIO; + if (!dc->bdev->bd_disk->fops->ioctl) + return -ENOTTY; + return dc->bdev->bd_disk->fops->ioctl(dc->bdev, mode, cmd, arg); +} + +void bch_cached_dev_request_init(struct cached_dev *dc) +{ + 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 int sectors) +{ + unsigned int bytes = min(sectors, bio_sectors(bio)) << 9; + + swap(bio->bi_iter.bi_size, bytes); + zero_fill_bio(bio); + swap(bio->bi_iter.bi_size, bytes); + + bio_advance(bio, bytes); + + if (!bio->bi_iter.bi_size) + return MAP_DONE; + + return MAP_CONTINUE; +} + +static void flash_dev_nodata(struct closure *cl) +{ + struct search *s = container_of(cl, struct search, cl); + + if (s->iop.flush_journal) + bch_journal_meta(s->iop.c, cl); + + continue_at(cl, search_free, NULL); +} + +void flash_dev_submit_bio(struct bio *bio) +{ + struct search *s; + struct closure *cl; + struct bcache_device *d = bio->bi_bdev->bd_disk->private_data; + + if (unlikely(d->c && test_bit(CACHE_SET_IO_DISABLE, &d->c->flags))) { + bio->bi_status = BLK_STS_IOERR; + bio_endio(bio); + return; + } + + s = search_alloc(bio, d, bio->bi_bdev, bio_start_io_acct(bio)); + cl = &s->cl; + bio = &s->bio.bio; + + trace_bcache_request_start(s->d, bio); + + if (!bio->bi_iter.bi_size) { + /* + * can't call bch_journal_meta from under submit_bio_noacct + */ + continue_at_nobarrier(&s->cl, + flash_dev_nodata, + bcache_wq); + return; + } else if (bio_data_dir(bio)) { + bch_keybuf_check_overlapping(&s->iop.c->moving_gc_keys, + &KEY(d->id, bio->bi_iter.bi_sector, 0), + &KEY(d->id, bio_end_sector(bio), 0)); + + s->iop.bypass = (bio_op(bio) == REQ_OP_DISCARD) != 0; + s->iop.writeback = true; + s->iop.bio = bio; + + closure_call(&s->iop.cl, bch_data_insert, NULL, cl); + } else { + closure_call(&s->iop.cl, cache_lookup, NULL, 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; +} + +void bch_flash_dev_request_init(struct bcache_device *d) +{ + d->cache_miss = flash_dev_cache_miss; + d->ioctl = flash_dev_ioctl; +} + +void bch_request_exit(void) +{ + 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; + + return 0; +} |