bcache: Refactor request_write()
Try to improve some of the naming a bit to be more consistent, and also improve the flow of control in request_write() a bit. Signed-off-by: Kent Overstreet <kmo@daterainc.com>
This commit is contained in:
Kent Overstreet
Родитель
c2f95ae2eb
Коммит
84f0db03ea
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@ -260,7 +260,7 @@ struct btree_op {
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} type:8;
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unsigned csum:1;
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unsigned skip:1;
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unsigned bypass:1;
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unsigned flush_journal:1;
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unsigned insert_data_done:1;
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@ -25,8 +25,6 @@
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struct kmem_cache *bch_search_cache;
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static void check_should_skip(struct cached_dev *, struct search *);
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/* Cgroup interface */
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#ifdef CONFIG_CGROUP_BCACHE
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@ -480,7 +478,7 @@ static void bch_insert_data_loop(struct closure *cl)
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struct search *s = container_of(op, struct search, op);
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struct bio *bio = op->cache_bio, *n;
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if (op->skip)
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if (op->bypass)
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return bio_invalidate(cl);
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if (atomic_sub_return(bio_sectors(bio), &op->c->sectors_to_gc) < 0) {
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@ -557,7 +555,7 @@ err:
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* we wait for buckets to be freed up, so just invalidate the
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* rest of the write.
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*/
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op->skip = true;
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op->bypass = true;
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return bio_invalidate(cl);
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} else {
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/*
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@ -590,8 +588,8 @@ err:
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* It inserts the data in op->cache_bio; bi_sector is used for the key offset,
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* and op->inode is used for the key inode.
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*
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* If op->skip is true, instead of inserting the data it invalidates the region
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* of the cache represented by op->cache_bio and op->inode.
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* If op->bypass is true, instead of inserting the data it invalidates the
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* region of the cache represented by op->cache_bio and op->inode.
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*/
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void bch_insert_data(struct closure *cl)
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{
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@ -717,7 +715,6 @@ static struct search *search_alloc(struct bio *bio, struct bcache_device *d)
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s->orig_bio = bio;
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s->write = (bio->bi_rw & REQ_WRITE) != 0;
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s->op.flush_journal = (bio->bi_rw & (REQ_FLUSH|REQ_FUA)) != 0;
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s->op.skip = (bio->bi_rw & REQ_DISCARD) != 0;
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s->recoverable = 1;
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s->start_time = jiffies;
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do_bio_hook(s);
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@ -757,6 +754,134 @@ static void cached_dev_bio_complete(struct closure *cl)
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cached_dev_put(dc);
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}
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unsigned bch_get_congested(struct cache_set *c)
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{
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int i;
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long rand;
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if (!c->congested_read_threshold_us &&
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!c->congested_write_threshold_us)
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return 0;
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i = (local_clock_us() - c->congested_last_us) / 1024;
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if (i < 0)
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return 0;
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i += atomic_read(&c->congested);
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if (i >= 0)
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return 0;
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i += CONGESTED_MAX;
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if (i > 0)
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i = fract_exp_two(i, 6);
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rand = get_random_int();
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i -= bitmap_weight(&rand, BITS_PER_LONG);
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return i > 0 ? i : 1;
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}
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static void add_sequential(struct task_struct *t)
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{
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ewma_add(t->sequential_io_avg,
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t->sequential_io, 8, 0);
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t->sequential_io = 0;
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}
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static struct hlist_head *iohash(struct cached_dev *dc, uint64_t k)
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{
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return &dc->io_hash[hash_64(k, RECENT_IO_BITS)];
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}
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static bool check_should_bypass(struct cached_dev *dc, struct search *s)
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{
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struct cache_set *c = s->op.c;
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struct bio *bio = &s->bio.bio;
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unsigned mode = cache_mode(dc, bio);
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unsigned sectors, congested = bch_get_congested(c);
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if (atomic_read(&dc->disk.detaching) ||
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c->gc_stats.in_use > CUTOFF_CACHE_ADD ||
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(bio->bi_rw & REQ_DISCARD))
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goto skip;
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if (mode == CACHE_MODE_NONE ||
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(mode == CACHE_MODE_WRITEAROUND &&
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(bio->bi_rw & REQ_WRITE)))
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goto skip;
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if (bio->bi_sector & (c->sb.block_size - 1) ||
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bio_sectors(bio) & (c->sb.block_size - 1)) {
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pr_debug("skipping unaligned io");
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goto skip;
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}
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if (!congested && !dc->sequential_cutoff)
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goto rescale;
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if (!congested &&
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mode == CACHE_MODE_WRITEBACK &&
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(bio->bi_rw & REQ_WRITE) &&
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(bio->bi_rw & REQ_SYNC))
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goto rescale;
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if (dc->sequential_merge) {
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struct io *i;
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spin_lock(&dc->io_lock);
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hlist_for_each_entry(i, iohash(dc, bio->bi_sector), hash)
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if (i->last == bio->bi_sector &&
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time_before(jiffies, i->jiffies))
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goto found;
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i = list_first_entry(&dc->io_lru, struct io, lru);
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add_sequential(s->task);
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i->sequential = 0;
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found:
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if (i->sequential + bio->bi_size > i->sequential)
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i->sequential += bio->bi_size;
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i->last = bio_end_sector(bio);
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i->jiffies = jiffies + msecs_to_jiffies(5000);
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s->task->sequential_io = i->sequential;
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hlist_del(&i->hash);
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hlist_add_head(&i->hash, iohash(dc, i->last));
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list_move_tail(&i->lru, &dc->io_lru);
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spin_unlock(&dc->io_lock);
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} else {
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s->task->sequential_io = bio->bi_size;
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add_sequential(s->task);
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}
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sectors = max(s->task->sequential_io,
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s->task->sequential_io_avg) >> 9;
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if (dc->sequential_cutoff &&
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sectors >= dc->sequential_cutoff >> 9) {
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trace_bcache_bypass_sequential(s->orig_bio);
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goto skip;
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}
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if (congested && sectors >= congested) {
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trace_bcache_bypass_congested(s->orig_bio);
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goto skip;
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}
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rescale:
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bch_rescale_priorities(c, bio_sectors(bio));
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return false;
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skip:
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bch_mark_sectors_bypassed(s, bio_sectors(bio));
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return true;
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}
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/* Process reads */
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static void cached_dev_read_complete(struct closure *cl)
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@ -854,8 +979,8 @@ static void request_read_done_bh(struct closure *cl)
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struct search *s = container_of(cl, struct search, cl);
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struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
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bch_mark_cache_accounting(s, !s->cache_miss, s->op.skip);
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trace_bcache_read(s->orig_bio, !s->cache_miss, s->op.skip);
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bch_mark_cache_accounting(s, !s->cache_miss, s->op.bypass);
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trace_bcache_read(s->orig_bio, !s->cache_miss, s->op.bypass);
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if (s->error)
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continue_at_nobarrier(cl, request_read_error, bcache_wq);
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@ -873,7 +998,7 @@ static int cached_dev_cache_miss(struct btree *b, struct search *s,
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struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
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struct bio *miss;
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if (s->cache_miss || s->op.skip) {
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if (s->cache_miss || s->op.bypass) {
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miss = bch_bio_split(bio, sectors, GFP_NOIO, s->d->bio_split);
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if (miss == bio)
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s->op.lookup_done = true;
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@ -940,9 +1065,7 @@ static void request_read(struct cached_dev *dc, struct search *s)
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{
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struct closure *cl = &s->cl;
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check_should_skip(dc, s);
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closure_call(&s->op.cl, btree_read_async, NULL, cl);
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continue_at(cl, request_read_done_bh, NULL);
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}
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@ -961,41 +1084,48 @@ static void request_write(struct cached_dev *dc, struct search *s)
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{
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struct closure *cl = &s->cl;
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struct bio *bio = &s->bio.bio;
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struct bkey start, end;
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start = KEY(dc->disk.id, bio->bi_sector, 0);
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end = KEY(dc->disk.id, bio_end_sector(bio), 0);
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struct bkey start = KEY(dc->disk.id, bio->bi_sector, 0);
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struct bkey end = KEY(dc->disk.id, bio_end_sector(bio), 0);
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bch_keybuf_check_overlapping(&s->op.c->moving_gc_keys, &start, &end);
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check_should_skip(dc, s);
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down_read_non_owner(&dc->writeback_lock);
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if (bch_keybuf_check_overlapping(&dc->writeback_keys, &start, &end)) {
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s->op.skip = false;
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/*
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* We overlap with some dirty data undergoing background
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* writeback, force this write to writeback
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*/
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s->op.bypass = false;
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s->writeback = true;
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}
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/*
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* Discards aren't _required_ to do anything, so skipping if
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* check_overlapping returned true is ok
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*
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* But check_overlapping drops dirty keys for which io hasn't started,
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* so we still want to call it.
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*/
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if (bio->bi_rw & REQ_DISCARD)
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goto skip;
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s->op.bypass = true;
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if (should_writeback(dc, s->orig_bio,
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cache_mode(dc, bio),
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s->op.skip)) {
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s->op.skip = false;
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s->op.bypass)) {
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s->op.bypass = false;
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s->writeback = true;
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}
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if (s->op.skip)
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goto skip;
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trace_bcache_write(s->orig_bio, s->writeback, s->op.bypass);
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trace_bcache_write(s->orig_bio, s->writeback, s->op.skip);
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if (s->op.bypass) {
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s->op.cache_bio = s->orig_bio;
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bio_get(s->op.cache_bio);
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if (!s->writeback) {
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s->op.cache_bio = bio_clone_bioset(bio, GFP_NOIO,
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dc->disk.bio_split);
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closure_bio_submit(bio, cl, s->d);
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} else {
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if (!(bio->bi_rw & REQ_DISCARD) ||
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blk_queue_discard(bdev_get_queue(dc->bdev)))
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closure_bio_submit(bio, cl, s->d);
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} else if (s->writeback) {
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bch_writeback_add(dc);
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s->op.cache_bio = bio;
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@ -1011,21 +1141,15 @@ static void request_write(struct cached_dev *dc, struct search *s)
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closure_bio_submit(flush, cl, s->d);
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}
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} else {
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s->op.cache_bio = bio_clone_bioset(bio, GFP_NOIO,
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dc->disk.bio_split);
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closure_bio_submit(bio, cl, s->d);
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}
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out:
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closure_call(&s->op.cl, bch_insert_data, NULL, cl);
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continue_at(cl, cached_dev_write_complete, NULL);
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skip:
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s->op.skip = true;
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s->op.cache_bio = s->orig_bio;
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bio_get(s->op.cache_bio);
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if ((bio->bi_rw & REQ_DISCARD) &&
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!blk_queue_discard(bdev_get_queue(dc->bdev)))
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goto out;
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closure_bio_submit(bio, cl, s->d);
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goto out;
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}
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static void request_nodata(struct cached_dev *dc, struct search *s)
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@ -1033,14 +1157,10 @@ static void request_nodata(struct cached_dev *dc, struct search *s)
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struct closure *cl = &s->cl;
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struct bio *bio = &s->bio.bio;
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if (bio->bi_rw & REQ_DISCARD) {
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request_write(dc, s);
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return;
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}
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if (s->op.flush_journal)
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bch_journal_meta(s->op.c, cl);
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/* If it's a flush, we send the flush to the backing device too */
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closure_bio_submit(bio, cl, s->d);
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continue_at(cl, cached_dev_bio_complete, NULL);
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@ -1048,134 +1168,6 @@ static void request_nodata(struct cached_dev *dc, struct search *s)
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/* Cached devices - read & write stuff */
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unsigned bch_get_congested(struct cache_set *c)
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{
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int i;
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long rand;
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if (!c->congested_read_threshold_us &&
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!c->congested_write_threshold_us)
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return 0;
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i = (local_clock_us() - c->congested_last_us) / 1024;
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if (i < 0)
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return 0;
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i += atomic_read(&c->congested);
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if (i >= 0)
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return 0;
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|
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i += CONGESTED_MAX;
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|
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if (i > 0)
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i = fract_exp_two(i, 6);
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rand = get_random_int();
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i -= bitmap_weight(&rand, BITS_PER_LONG);
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|
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return i > 0 ? i : 1;
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}
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static void add_sequential(struct task_struct *t)
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{
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ewma_add(t->sequential_io_avg,
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t->sequential_io, 8, 0);
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|
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t->sequential_io = 0;
|
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}
|
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|
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static struct hlist_head *iohash(struct cached_dev *dc, uint64_t k)
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{
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return &dc->io_hash[hash_64(k, RECENT_IO_BITS)];
|
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}
|
||||
|
||||
static void check_should_skip(struct cached_dev *dc, struct search *s)
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{
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struct cache_set *c = s->op.c;
|
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struct bio *bio = &s->bio.bio;
|
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unsigned mode = cache_mode(dc, bio);
|
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unsigned sectors, congested = bch_get_congested(c);
|
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|
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if (atomic_read(&dc->disk.detaching) ||
|
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c->gc_stats.in_use > CUTOFF_CACHE_ADD ||
|
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(bio->bi_rw & REQ_DISCARD))
|
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goto skip;
|
||||
|
||||
if (mode == CACHE_MODE_NONE ||
|
||||
(mode == CACHE_MODE_WRITEAROUND &&
|
||||
(bio->bi_rw & REQ_WRITE)))
|
||||
goto skip;
|
||||
|
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if (bio->bi_sector & (c->sb.block_size - 1) ||
|
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bio_sectors(bio) & (c->sb.block_size - 1)) {
|
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pr_debug("skipping unaligned io");
|
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goto skip;
|
||||
}
|
||||
|
||||
if (!congested && !dc->sequential_cutoff)
|
||||
goto rescale;
|
||||
|
||||
if (!congested &&
|
||||
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_sector(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);
|
||||
}
|
||||
|
||||
sectors = max(s->task->sequential_io,
|
||||
s->task->sequential_io_avg) >> 9;
|
||||
|
||||
if (dc->sequential_cutoff &&
|
||||
sectors >= dc->sequential_cutoff >> 9) {
|
||||
trace_bcache_bypass_sequential(s->orig_bio);
|
||||
goto skip;
|
||||
}
|
||||
|
||||
if (congested && sectors >= congested) {
|
||||
trace_bcache_bypass_congested(s->orig_bio);
|
||||
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;
|
||||
|
|
@ -1195,12 +1187,16 @@ static void cached_dev_make_request(struct request_queue *q, struct bio *bio)
|
|||
s = search_alloc(bio, d);
|
||||
trace_bcache_request_start(s, bio);
|
||||
|
||||
if (!bio_has_data(bio))
|
||||
if (!bio->bi_size)
|
||||
request_nodata(dc, s);
|
||||
else if (rw)
|
||||
request_write(dc, s);
|
||||
else
|
||||
request_read(dc, s);
|
||||
else {
|
||||
s->op.bypass = check_should_bypass(dc, s);
|
||||
|
||||
if (rw)
|
||||
request_write(dc, s);
|
||||
else
|
||||
request_read(dc, s);
|
||||
}
|
||||
} else {
|
||||
if ((bio->bi_rw & REQ_DISCARD) &&
|
||||
!blk_queue_discard(bdev_get_queue(dc->bdev)))
|
||||
|
|
@ -1298,21 +1294,21 @@ static void flash_dev_make_request(struct request_queue *q, struct bio *bio)
|
|||
|
||||
trace_bcache_request_start(s, bio);
|
||||
|
||||
if (bio_has_data(bio) && !rw) {
|
||||
closure_call(&s->op.cl, btree_read_async, NULL, cl);
|
||||
} else if (bio_has_data(bio) || s->op.skip) {
|
||||
if (!bio->bi_size) {
|
||||
if (s->op.flush_journal)
|
||||
bch_journal_meta(s->op.c, cl);
|
||||
} else if (rw) {
|
||||
bch_keybuf_check_overlapping(&s->op.c->moving_gc_keys,
|
||||
&KEY(d->id, bio->bi_sector, 0),
|
||||
&KEY(d->id, bio_end_sector(bio), 0));
|
||||
|
||||
s->op.bypass = (bio->bi_rw & REQ_DISCARD) != 0;
|
||||
s->writeback = true;
|
||||
s->op.cache_bio = bio;
|
||||
|
||||
closure_call(&s->op.cl, bch_insert_data, NULL, cl);
|
||||
} else {
|
||||
/* No data - probably a cache flush */
|
||||
if (s->op.flush_journal)
|
||||
bch_journal_meta(s->op.c, cl);
|
||||
closure_call(&s->op.cl, btree_read_async, NULL, cl);
|
||||
}
|
||||
|
||||
continue_at(cl, search_free, NULL);
|
||||
|
|
|
|||
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