1 files changed, 541 insertions, 575 deletions

diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 786a1a4f74d8..fbcc851ed5a5 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -25,7 +25,7 @@
 
 struct kmem_cache *bch_search_cache;
 
-static void check_should_skip(struct cached_dev *, struct search *);
+static void bch_data_insert_start(struct closure *);
 
 /* Cgroup interface */
 
@@ -213,221 +213,79 @@ static void bio_csum(struct bio *bio, struct bkey *k)
 
 /* Insert data into cache */
 
-static void bio_invalidate(struct closure *cl)
+static void bch_data_insert_keys(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;
-	}
+	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;
 
 	/*
-	 * 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).
+	 * If we're looping, might already be waiting on
+	 * another journal write - can't wait on more than one journal write at
+	 * a time
+	 *
+	 * XXX: this looks wrong
 	 */
+#if 0
+	while (atomic_read(&s->cl.remaining) & CLOSURE_WAITING)
+		closure_sync(&s->cl);
+#endif
 
-	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;
+	if (!op->replace)
+		journal_ref = bch_journal(op->c, &op->insert_keys,
+					  op->flush_journal ? cl : NULL);
 
-		spin_lock(&c->data_bucket_lock);
+	ret = bch_btree_insert(op->c, &op->insert_keys,
+			       journal_ref, replace_key);
+	if (ret == -ESRCH) {
+		op->replace_collision = true;
+	} else if (ret) {
+		op->error		= -ENOMEM;
+		op->insert_data_done	= true;
 	}
 
-	/*
-	 * 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));
+	if (journal_ref)
+		atomic_dec_bug(journal_ref);
 
-	/* Set up the pointer to the space we're allocating: */
+	if (!op->insert_data_done)
+		continue_at(cl, bch_data_insert_start, bcache_wq);
 
-	for (i = 0; i < KEY_PTRS(&b->key); i++)
-		k->ptr[i] = b->key.ptr[i];
+	bch_keylist_free(&op->insert_keys);
+	closure_return(cl);
+}
 
-	sectors = min(sectors, b->sectors_free);
+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;
 
-	SET_KEY_OFFSET(k, KEY_OFFSET(k) + sectors);
-	SET_KEY_SIZE(k, sectors);
-	SET_KEY_PTRS(k, KEY_PTRS(&b->key));
+	pr_debug("invalidating %i sectors from %llu",
+		 bio_sectors(bio), (uint64_t) bio->bi_sector);
 
-	/*
-	 * 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;
+	while (bio_sectors(bio)) {
+		unsigned sectors = min(bio_sectors(bio),
+				       1U << (KEY_SIZE_BITS - 1));
 
-	b->sectors_free	-= sectors;
+		if (bch_keylist_realloc(&op->insert_keys, 0, op->c))
+			goto out;
 
-	for (i = 0; i < KEY_PTRS(&b->key); i++) {
-		SET_PTR_OFFSET(&b->key, i, PTR_OFFSET(&b->key, i) + sectors);
+		bio->bi_sector	+= sectors;
+		bio->bi_size	-= sectors << 9;
 
-		atomic_long_add(sectors,
-				&PTR_CACHE(c, &b->key, i)->sectors_written);
+		bch_keylist_add(&op->insert_keys,
+				&KEY(op->inode, bio->bi_sector, sectors));
 	}
 
-	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;
+	op->insert_data_done = true;
+	bio_put(bio);
+out:
+	continue_at(cl, bch_data_insert_keys, bcache_wq);
 }
 
-static void bch_insert_data_error(struct closure *cl)
+static void bch_data_insert_error(struct closure *cl)
 {
-	struct btree_op *op = container_of(cl, struct btree_op, 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
@@ -438,35 +296,34 @@ static void bch_insert_data_error(struct closure *cl)
 	 * from the keys we'll accomplish just that.
 	 */
 
-	struct bkey *src = op->keys.bottom, *dst = op->keys.bottom;
+	struct bkey *src = op->insert_keys.keys, *dst = op->insert_keys.keys;
 
-	while (src != op->keys.top) {
+	while (src != op->insert_keys.top) {
 		struct bkey *n = bkey_next(src);
 
 		SET_KEY_PTRS(src, 0);
-		bkey_copy(dst, src);
+		memmove(dst, src, bkey_bytes(src));
 
 		dst = bkey_next(dst);
 		src = n;
 	}
 
-	op->keys.top = dst;
+	op->insert_keys.top = dst;
 
-	bch_journal(cl);
+	bch_data_insert_keys(cl);
 }
 
-static void bch_insert_data_endio(struct bio *bio, int error)
+static void bch_data_insert_endio(struct bio *bio, int error)
 {
 	struct closure *cl = bio->bi_private;
-	struct btree_op *op = container_of(cl, struct btree_op, cl);
-	struct search *s = container_of(op, struct search, op);
+	struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
 
 	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);
+		if (op->writeback)
+			op->error = error;
+		else if (!op->replace)
+			set_closure_fn(cl, bch_data_insert_error, bcache_wq);
 		else
 			set_closure_fn(cl, NULL, NULL);
 	}
@@ -474,18 +331,17 @@ static void bch_insert_data_endio(struct bio *bio, int error)
 	bch_bbio_endio(op->c, bio, error, "writing data to cache");
 }
 
-static void bch_insert_data_loop(struct closure *cl)
+static void bch_data_insert_start(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;
+	struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
+	struct bio *bio = op->bio, *n;
 
-	if (op->skip)
-		return bio_invalidate(cl);
+	if (op->bypass)
+		return bch_data_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);
+		wake_up_gc(op->c);
 	}
 
 	/*
@@ -497,29 +353,30 @@ static void bch_insert_data_loop(struct closure *cl)
 	do {
 		unsigned i;
 		struct bkey *k;
-		struct bio_set *split = s->d
-			? s->d->bio_split : op->c->bio_split;
+		struct bio_set *split = op->c->bio_split;
 
 		/* 1 for the device pointer and 1 for the chksum */
-		if (bch_keylist_realloc(&op->keys,
+		if (bch_keylist_realloc(&op->insert_keys,
 					1 + (op->csum ? 1 : 0),
 					op->c))
-			continue_at(cl, bch_journal, bcache_wq);
+			continue_at(cl, bch_data_insert_keys, bcache_wq);
 
-		k = op->keys.top;
+		k = op->insert_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))
+		if (!bch_alloc_sectors(op->c, k, bio_sectors(bio),
+				       op->write_point, op->write_prio,
+				       op->writeback))
 			goto err;
 
 		n = bch_bio_split(bio, KEY_SIZE(k), GFP_NOIO, split);
 
-		n->bi_end_io	= bch_insert_data_endio;
+		n->bi_end_io	= bch_data_insert_endio;
 		n->bi_private	= cl;
 
-		if (s->writeback) {
+		if (op->writeback) {
 			SET_KEY_DIRTY(k, true);
 
 			for (i = 0; i < KEY_PTRS(k); i++)
@@ -532,17 +389,17 @@ static void bch_insert_data_loop(struct closure *cl)
 			bio_csum(n, k);
 
 		trace_bcache_cache_insert(k);
-		bch_keylist_push(&op->keys);
+		bch_keylist_push(&op->insert_keys);
 
 		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);
+	continue_at(cl, bch_data_insert_keys, bcache_wq);
 err:
 	/* bch_alloc_sectors() blocks if s->writeback = true */
-	BUG_ON(s->writeback);
+	BUG_ON(op->writeback);
 
 	/*
 	 * But if it's not a writeback write we'd rather just bail out if
@@ -550,15 +407,15 @@ err:
 	 * we might be starving btree writes for gc or something.
 	 */
 
-	if (s->write) {
+	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->skip = true;
-		return bio_invalidate(cl);
+		op->bypass = true;
+		return bch_data_invalidate(cl);
 	} else {
 		/*
 		 * From a cache miss, we can just insert the keys for the data
@@ -567,15 +424,15 @@ err:
 		op->insert_data_done = true;
 		bio_put(bio);
 
-		if (!bch_keylist_empty(&op->keys))
-			continue_at(cl, bch_journal, bcache_wq);
+		if (!bch_keylist_empty(&op->insert_keys))
+			continue_at(cl, bch_data_insert_keys, bcache_wq);
 		else
 			closure_return(cl);
 	}
 }
 
 /**
- * bch_insert_data - stick some data in the cache
+ * bch_data_insert - 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
@@ -587,56 +444,179 @@ err:
  * 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,
+ * It inserts the data in s->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.
+ * If s->bypass is true, instead of inserting the data it invalidates the
+ * region of the cache represented by s->cache_bio and op->inode.
  */
-void bch_insert_data(struct closure *cl)
+void bch_data_insert(struct closure *cl)
 {
-	struct btree_op *op = container_of(cl, struct btree_op, cl);
+	struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
+
+	trace_bcache_write(op->bio, op->writeback, op->bypass);
 
-	bch_keylist_init(&op->keys);
-	bio_get(op->cache_bio);
-	bch_insert_data_loop(cl);
+	bch_keylist_init(&op->insert_keys);
+	bio_get(op->bio);
+	bch_data_insert_start(cl);
 }
 
-void bch_btree_insert_async(struct closure *cl)
+/* Congested? */
+
+unsigned bch_get_congested(struct cache_set *c)
 {
-	struct btree_op *op = container_of(cl, struct btree_op, cl);
-	struct search *s = container_of(op, struct search, op);
+	int i;
+	long rand;
 
-	if (bch_btree_insert(op, op->c)) {
-		s->error		= -ENOMEM;
-		op->insert_data_done	= true;
-	}
+	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);
 
-	if (op->insert_data_done) {
-		bch_keylist_free(&op->keys);
-		closure_return(cl);
-	} else
-		continue_at(cl, bch_insert_data_loop, bcache_wq);
+	rand = get_random_int();
+	i -= bitmap_weight(&rand, BITS_PER_LONG);
+
+	return i > 0 ? i : 1;
 }
 
-/* Common code for the make_request functions */
+static void add_sequential(struct task_struct *t)
+{
+	ewma_add(t->sequential_io_avg,
+		 t->sequential_io, 8, 0);
 
-static void request_endio(struct bio *bio, int error)
+	t->sequential_io = 0;
+}
+
+static struct hlist_head *iohash(struct cached_dev *dc, uint64_t k)
 {
-	struct closure *cl = bio->bi_private;
+	return &dc->io_hash[hash_64(k, RECENT_IO_BITS)];
+}
 
-	if (error) {
-		struct search *s = container_of(cl, struct search, cl);
-		s->error = error;
-		/* Only cache read errors are recoverable */
-		s->recoverable = false;
+static bool check_should_bypass(struct cached_dev *dc, struct bio *bio)
+{
+	struct cache_set *c = dc->disk.c;
+	unsigned mode = cache_mode(dc, bio);
+	unsigned sectors, congested = bch_get_congested(c);
+	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->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;
 	}
 
-	bio_put(bio);
-	closure_put(cl);
+	if (bypass_torture_test(dc)) {
+		if ((get_random_int() & 3) == 3)
+			goto skip;
+		else
+			goto rescale;
+	}
+
+	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;
+
+	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(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);
+	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;
 }
 
-void bch_cache_read_endio(struct bio *bio, int error)
+/* Cache lookup */
+
+struct search {
+	/* Stack frame for bio_complete */
+	struct closure		cl;
+
+	struct bcache_device	*d;
+
+	struct bbio		bio;
+	struct bio		*orig_bio;
+	struct bio		*cache_miss;
+
+	unsigned		insert_bio_sectors;
+
+	unsigned		recoverable:1;
+	unsigned		unaligned_bvec:1;
+	unsigned		write:1;
+	unsigned		read_dirty_data:1;
+
+	unsigned long		start_time;
+
+	struct btree_op		op;
+	struct data_insert_op	iop;
+};
+
+static 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;
@@ -650,13 +630,113 @@ void bch_cache_read_endio(struct bio *bio, int error)
 	 */
 
 	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;
+		s->iop.error = error;
+	else if (ptr_stale(s->iop.c, &b->key, 0)) {
+		atomic_long_inc(&s->iop.c->cache_read_races);
+		s->iop.error = -EINTR;
 	}
 
-	bch_bbio_endio(s->op.c, bio, error, "reading from cache");
+	bch_bbio_endio(s->iop.c, bio, error, "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 ptr;
+
+	if (bkey_cmp(k, &KEY(s->iop.inode, bio->bi_sector, 0)) <= 0)
+		return MAP_CONTINUE;
+
+	if (KEY_INODE(k) != s->iop.inode ||
+	    KEY_START(k) > bio->bi_sector) {
+		unsigned bio_sectors = bio_sectors(bio);
+		unsigned sectors = KEY_INODE(k) == s->iop.inode
+			? min_t(uint64_t, INT_MAX,
+				KEY_START(k) - bio->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 = bch_bio_split(bio, min_t(uint64_t, INT_MAX,
+				     KEY_OFFSET(k) - bio->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_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;
+
+	int ret = bch_btree_map_keys(&s->op, s->iop.c,
+				     &KEY(s->iop.inode, bio->bi_sector, 0),
+				     cache_lookup_fn, MAP_END_KEY);
+	if (ret == -EAGAIN)
+		continue_at(cl, cache_lookup, bcache_wq);
+
+	closure_return(cl);
+}
+
+/* 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->iop.error = error;
+		/* Only cache read errors are recoverable */
+		s->recoverable = false;
+	}
+
+	bio_put(bio);
+	closure_put(cl);
 }
 
 static void bio_complete(struct search *s)
@@ -670,8 +750,8 @@ static void bio_complete(struct search *s)
 		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);
+		trace_bcache_request_end(s->d, s->orig_bio);
+		bio_endio(s->orig_bio, s->iop.error);
 		s->orig_bio = NULL;
 	}
 }
@@ -691,8 +771,8 @@ 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->iop.bio)
+		bio_put(s->iop.bio);
 
 	if (s->unaligned_bvec)
 		mempool_free(s->bio.bio.bi_io_vec, s->d->unaligned_bvec);
@@ -703,21 +783,22 @@ static void search_free(struct closure *cl)
 
 static struct search *search_alloc(struct bio *bio, struct bcache_device *d)
 {
+	struct search *s;
 	struct bio_vec *bv;
-	struct search *s = mempool_alloc(d->c->search, GFP_NOIO);
-	memset(s, 0, offsetof(struct search, op.keys));
+
+	s = mempool_alloc(d->c->search, GFP_NOIO);
+	memset(s, 0, offsetof(struct search, iop.insert_keys));
 
 	__closure_init(&s->cl, NULL);
 
-	s->op.inode		= d->id;
-	s->op.c			= d->c;
+	s->iop.inode		= d->id;
+	s->iop.c		= d->c;
 	s->d			= d;
 	s->op.lock		= -1;
-	s->task			= current;
+	s->iop.write_point	= hash_long((unsigned long) current, 16);
 	s->orig_bio		= bio;
 	s->write		= (bio->bi_rw & REQ_WRITE) != 0;
-	s->op.flush_journal	= (bio->bi_rw & (REQ_FLUSH|REQ_FUA)) != 0;
-	s->op.skip		= (bio->bi_rw & REQ_DISCARD) != 0;
+	s->iop.flush_journal	= (bio->bi_rw & (REQ_FLUSH|REQ_FUA)) != 0;
 	s->recoverable		= 1;
 	s->start_time		= jiffies;
 	do_bio_hook(s);
@@ -734,18 +815,6 @@ static struct search *search_alloc(struct bio *bio, struct bcache_device *d)
 	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)
@@ -759,27 +828,28 @@ static void cached_dev_bio_complete(struct closure *cl)
 
 /* Process reads */
 
-static void cached_dev_read_complete(struct closure *cl)
+static void cached_dev_cache_miss_done(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->iop.replace_collision)
+		bch_mark_cache_miss_collision(s->iop.c, s->d);
 
-	if (s->op.cache_bio) {
+	if (s->iop.bio) {
 		int i;
 		struct bio_vec *bv;
 
-		__bio_for_each_segment(bv, s->op.cache_bio, i, 0)
+		bio_for_each_segment_all(bv, s->iop.bio, i)
 			__free_page(bv->bv_page);
 	}
 
 	cached_dev_bio_complete(cl);
 }
 
-static void request_read_error(struct closure *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;
 	struct bio_vec *bv;
 	int i;
 
@@ -787,7 +857,7 @@ static void request_read_error(struct closure *cl)
 		/* Retry from the backing device: */
 		trace_bcache_read_retry(s->orig_bio);
 
-		s->error = 0;
+		s->iop.error = 0;
 		bv = s->bio.bio.bi_io_vec;
 		do_bio_hook(s);
 		s->bio.bio.bi_io_vec = bv;
@@ -803,146 +873,148 @@ static void request_read_error(struct closure *cl)
 
 		/* XXX: invalidate cache */
 
-		closure_bio_submit(&s->bio.bio, &s->cl, s->d);
+		closure_bio_submit(bio, cl, s->d);
 	}
 
-	continue_at(cl, cached_dev_read_complete, NULL);
+	continue_at(cl, cached_dev_cache_miss_done, NULL);
 }
 
-static void request_read_done(struct closure *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);
 
 	/*
-	 * s->cache_bio != NULL implies that we had a cache miss; cache_bio now
-	 * contains data ready to be inserted into the cache.
+	 * 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) {
-		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);
+	if (s->iop.bio) {
+		bio_reset(s->iop.bio);
+		s->iop.bio->bi_sector = s->cache_miss->bi_sector;
+		s->iop.bio->bi_bdev = s->cache_miss->bi_bdev;
+		s->iop.bio->bi_size = s->insert_bio_sectors << 9;
+		bch_bio_map(s->iop.bio, NULL);
 
-		bio_copy_data(s->cache_miss, s->op.cache_bio);
+		bio_copy_data(s->cache_miss, s->iop.bio);
 
 		bio_put(s->cache_miss);
 		s->cache_miss = NULL;
 	}
 
-	if (verify(dc, &s->bio.bio) && s->recoverable)
-		bch_data_verify(s);
+	if (verify(dc, &s->bio.bio) && s->recoverable &&
+	    !s->unaligned_bvec && !s->read_dirty_data)
+		bch_data_verify(dc, s->orig_bio);
 
 	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);
+	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_read_complete, NULL);
+	continue_at(cl, cached_dev_cache_miss_done, NULL);
 }
 
-static void request_read_done_bh(struct closure *cl)
+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, !s->cache_miss, s->op.skip);
-	trace_bcache_read(s->orig_bio, !s->cache_miss, s->op.skip);
+	bch_mark_cache_accounting(s->iop.c, s->d,
+				  !s->cache_miss, s->iop.bypass);
+	trace_bcache_read(s->orig_bio, !s->cache_miss, s->iop.bypass);
 
-	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);
+	if (s->iop.error)
+		continue_at_nobarrier(cl, cached_dev_read_error, bcache_wq);
+	else if (s->iop.bio || verify(dc, &s->bio.bio))
+		continue_at_nobarrier(cl, cached_dev_read_done, bcache_wq);
 	else
-		continue_at_nobarrier(cl, cached_dev_read_complete, NULL);
+		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 sectors)
 {
-	int ret = 0;
-	unsigned reada;
+	int ret = MAP_CONTINUE;
+	unsigned reada = 0;
 	struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
-	struct bio *miss;
+	struct bio *miss, *cache_bio;
 
-	miss = bch_bio_split(bio, sectors, GFP_NOIO, s->d->bio_split);
-	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)
+	if (s->cache_miss || s->iop.bypass) {
+		miss = bch_bio_split(bio, sectors, GFP_NOIO, s->d->bio_split);
+		ret = miss == bio ? MAP_DONE : MAP_CONTINUE;
 		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_sector(miss) + reada > bdev_sectors(miss->bi_bdev))
-			reada = bdev_sectors(miss->bi_bdev) -
-				bio_end_sector(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 (!(bio->bi_rw & REQ_RAHEAD) &&
+	    !(bio->bi_rw & REQ_META) &&
+	    s->iop.c->gc_stats.in_use < CUTOFF_CACHE_READA)
+		reada = min_t(sector_t, dc->readahead >> 9,
+			      bdev_sectors(bio->bi_bdev) - bio_end_sector(bio));
 
-	if (!s->op.cache_bio)
-		goto out_submit;
+	s->insert_bio_sectors = min(sectors, bio_sectors(bio) + reada);
 
-	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->iop.replace_key = KEY(s->iop.inode,
+				 bio->bi_sector + s->insert_bio_sectors,
+				 s->insert_bio_sectors);
 
-	s->op.cache_bio->bi_end_io	= request_endio;
-	s->op.cache_bio->bi_private	= &s->cl;
+	ret = bch_btree_insert_check_key(b, &s->op, &s->iop.replace_key);
+	if (ret)
+		return ret;
+
+	s->iop.replace = true;
+
+	miss = bch_bio_split(bio, sectors, GFP_NOIO, s->d->bio_split);
 
 	/* 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;
+	ret = miss == bio ? MAP_DONE : -EINTR;
 
-	bch_bio_map(s->op.cache_bio, NULL);
-	if (bio_alloc_pages(s->op.cache_bio, __GFP_NOWARN|GFP_NOIO))
+	cache_bio = bio_alloc_bioset(GFP_NOWAIT,
+			DIV_ROUND_UP(s->insert_bio_sectors, PAGE_SECTORS),
+			dc->disk.bio_split);
+	if (!cache_bio)
+		goto out_submit;
+
+	cache_bio->bi_sector	= miss->bi_sector;
+	cache_bio->bi_bdev	= miss->bi_bdev;
+	cache_bio->bi_size	= s->insert_bio_sectors << 9;
+
+	cache_bio->bi_end_io	= request_endio;
+	cache_bio->bi_private	= &s->cl;
+
+	bch_bio_map(cache_bio, NULL);
+	if (bio_alloc_pages(cache_bio, __GFP_NOWARN|GFP_NOIO))
 		goto out_put;
 
-	s->cache_miss = miss;
-	bio_get(s->op.cache_bio);
+	if (reada)
+		bch_mark_cache_readahead(s->iop.c, s->d);
 
-	closure_bio_submit(s->op.cache_bio, &s->cl, s->d);
+	s->cache_miss	= miss;
+	s->iop.bio	= cache_bio;
+	bio_get(cache_bio);
+	closure_bio_submit(cache_bio, &s->cl, s->d);
 
 	return ret;
 out_put:
-	bio_put(s->op.cache_bio);
-	s->op.cache_bio = NULL;
+	bio_put(cache_bio);
 out_submit:
+	miss->bi_end_io		= request_endio;
+	miss->bi_private	= &s->cl;
 	closure_bio_submit(miss, &s->cl, s->d);
 	return ret;
 }
 
-static void request_read(struct cached_dev *dc, struct search *s)
+static void cached_dev_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);
+	closure_call(&s->iop.cl, cache_lookup, NULL, cl);
+	continue_at(cl, cached_dev_read_done_bh, NULL);
 }
 
 /* Process writes */
@@ -956,88 +1028,85 @@ static void cached_dev_write_complete(struct closure *cl)
 	cached_dev_bio_complete(cl);
 }
 
-static void request_write(struct cached_dev *dc, struct search *s)
+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, end;
-	start = KEY(dc->disk.id, bio->bi_sector, 0);
-	end = KEY(dc->disk.id, bio_end_sector(bio), 0);
+	struct bkey start = KEY(dc->disk.id, bio->bi_sector, 0);
+	struct bkey end = KEY(dc->disk.id, bio_end_sector(bio), 0);
 
-	bch_keybuf_check_overlapping(&s->op.c->moving_gc_keys, &start, &end);
+	bch_keybuf_check_overlapping(&s->iop.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;
+		/*
+		 * 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->bi_rw & REQ_DISCARD)
-		goto skip;
+		s->iop.bypass = true;
 
 	if (should_writeback(dc, s->orig_bio,
 			     cache_mode(dc, bio),
-			     s->op.skip)) {
-		s->op.skip = false;
-		s->writeback = true;
+			     s->iop.bypass)) {
+		s->iop.bypass = false;
+		s->iop.writeback = true;
 	}
 
-	if (s->op.skip)
-		goto skip;
-
-	trace_bcache_write(s->orig_bio, s->writeback, s->op.skip);
+	if (s->iop.bypass) {
+		s->iop.bio = s->orig_bio;
+		bio_get(s->iop.bio);
 
-	if (!s->writeback) {
-		s->op.cache_bio = bio_clone_bioset(bio, GFP_NOIO,
-						   dc->disk.bio_split);
-
-		closure_bio_submit(bio, cl, s->d);
-	} else {
+		if (!(bio->bi_rw & REQ_DISCARD) ||
+		    blk_queue_discard(bdev_get_queue(dc->bdev)))
+			closure_bio_submit(bio, cl, s->d);
+	} else if (s->iop.writeback) {
 		bch_writeback_add(dc);
+		s->iop.bio = bio;
 
-		if (s->op.flush_journal) {
+		if (bio->bi_rw & REQ_FLUSH) {
 			/* Also need to send a flush to the backing device */
-			s->op.cache_bio = bio_clone_bioset(bio, GFP_NOIO,
-							   dc->disk.bio_split);
+			struct bio *flush = bio_alloc_bioset(GFP_NOIO, 0,
+							     dc->disk.bio_split);
 
-			bio->bi_size = 0;
-			bio->bi_vcnt = 0;
-			closure_bio_submit(bio, cl, s->d);
-		} else {
-			s->op.cache_bio = bio;
+			flush->bi_rw	= WRITE_FLUSH;
+			flush->bi_bdev	= bio->bi_bdev;
+			flush->bi_end_io = request_endio;
+			flush->bi_private = cl;
+
+			closure_bio_submit(flush, cl, s->d);
 		}
-	}
-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);
+	} else {
+		s->iop.bio = bio_clone_bioset(bio, GFP_NOIO,
+					      dc->disk.bio_split);
 
-	if ((bio->bi_rw & REQ_DISCARD) &&
-	    !blk_queue_discard(bdev_get_queue(dc->bdev)))
-		goto out;
+		closure_bio_submit(bio, cl, s->d);
+	}
 
-	closure_bio_submit(bio, cl, s->d);
-	goto out;
+	closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
+	continue_at(cl, cached_dev_write_complete, NULL);
 }
 
-static void request_nodata(struct cached_dev *dc, struct search *s)
+static void cached_dev_nodata(struct closure *cl)
 {
-	struct closure *cl = &s->cl;
+	struct search *s = container_of(cl, struct search, 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);
+	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 */
 	closure_bio_submit(bio, cl, s->d);
 
 	continue_at(cl, cached_dev_bio_complete, NULL);
@@ -1045,134 +1114,6 @@ static void request_nodata(struct cached_dev *dc, struct search *s)
 
 /* Cached devices - read & write stuff */
 
-unsigned bch_get_congested(struct cache_set *c)
-{
-	int i;
-	long rand;
-
-	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);
-
-	rand = get_random_int();
-	i -= bitmap_weight(&rand, BITS_PER_LONG);
-
-	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 void check_should_skip(struct cached_dev *dc, struct search *s)
-{
-	struct cache_set *c = s->op.c;
-	struct bio *bio = &s->bio.bio;
-	unsigned mode = cache_mode(dc, bio);
-	unsigned sectors, congested = bch_get_congested(c);
-
-	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 (!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;
@@ -1190,14 +1131,24 @@ static void cached_dev_make_request(struct request_queue *q, struct bio *bio)
 
 	if (cached_dev_get(dc)) {
 		s = search_alloc(bio, d);
-		trace_bcache_request_start(s, bio);
+		trace_bcache_request_start(s->d, bio);
+
+		if (!bio->bi_size) {
+			/*
+			 * can't call bch_journal_meta from under
+			 * generic_make_request
+			 */
+			continue_at_nobarrier(&s->cl,
+					      cached_dev_nodata,
+					      bcache_wq);
+		} else {
+			s->iop.bypass = check_should_bypass(dc, bio);
 
-		if (!bio_has_data(bio))
-			request_nodata(dc, s);
-		else if (rw)
-			request_write(dc, s);
-		else
-			request_read(dc, s);
+			if (rw)
+				cached_dev_write(dc, s);
+			else
+				cached_dev_read(dc, s);
+		}
 	} else {
 		if ((bio->bi_rw & REQ_DISCARD) &&
 		    !blk_queue_discard(bdev_get_queue(dc->bdev)))
@@ -1272,9 +1223,19 @@ static int flash_dev_cache_miss(struct btree *b, struct search *s,
 	bio_advance(bio, min(sectors << 9, bio->bi_size));
 
 	if (!bio->bi_size)
-		s->op.lookup_done = true;
+		return MAP_DONE;
 
-	return 0;
+	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);
 }
 
 static void flash_dev_make_request(struct request_queue *q, struct bio *bio)
@@ -1293,23 +1254,28 @@ static void flash_dev_make_request(struct request_queue *q, struct bio *bio)
 	cl = &s->cl;
 	bio = &s->bio.bio;
 
-	trace_bcache_request_start(s, bio);
+	trace_bcache_request_start(s->d, 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) {
-		bch_keybuf_check_overlapping(&s->op.c->moving_gc_keys,
+	if (!bio->bi_size) {
+		/*
+		 * can't call bch_journal_meta from under
+		 * generic_make_request
+		 */
+		continue_at_nobarrier(&s->cl,
+				      flash_dev_nodata,
+				      bcache_wq);
+	} else if (rw) {
+		bch_keybuf_check_overlapping(&s->iop.c->moving_gc_keys,
 					&KEY(d->id, bio->bi_sector, 0),
 					&KEY(d->id, bio_end_sector(bio), 0));
 
-		s->writeback	= true;
-		s->op.cache_bio	= bio;
+		s->iop.bypass		= (bio->bi_rw & REQ_DISCARD) != 0;
+		s->iop.writeback	= true;
+		s->iop.bio		= bio;
 
-		closure_call(&s->op.cl, bch_insert_data, NULL, cl);
+		closure_call(&s->iop.cl, bch_data_insert, NULL, cl);
 	} else {
-		/* No data - probably a cache flush */
-		if (s->op.flush_journal)
-			bch_journal_meta(s->op.c, cl);
+		closure_call(&s->iop.cl, cache_lookup, NULL, cl);
 	}
 
 	continue_at(cl, search_free, NULL);