Merge tag 'dm-4.9-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper updates from Mike Snitzer:

 - various fixes and cleanups for request-based DM core

 - add support for delaying the requeue of requests; used by DM
   multipath when all paths have failed and 'queue_if_no_path' is
   enabled

 - DM cache improvements to speedup the loading metadata and the writing
   of the hint array

 - fix potential for a dm-crypt crash on device teardown

 - remove dm_bufio_cond_resched() and just using cond_resched()

 - change DM multipath to return a reservation conflict error
   immediately; rather than failing the path and retrying (potentially
   indefinitely)

* tag 'dm-4.9-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (24 commits)
  dm mpath: always return reservation conflict without failing over
  dm bufio: remove dm_bufio_cond_resched()
  dm crypt: fix crash on exit
  dm cache metadata: switch to using the new cursor api for loading metadata
  dm array: introduce cursor api
  dm btree: introduce cursor api
  dm cache policy smq: distribute entries to random levels when switching to smq
  dm cache: speed up writing of the hint array
  dm array: add dm_array_new()
  dm mpath: delay the requeue of blk-mq requests while all paths down
  dm mpath: use dm_mq_kick_requeue_list()
  dm rq: introduce dm_mq_kick_requeue_list()
  dm rq: reduce arguments passed to map_request() and dm_requeue_original_request()
  dm rq: add DM_MAPIO_DELAY_REQUEUE to delay requeue of blk-mq requests
  dm: convert wait loops to use autoremove_wake_function()
  dm: use signal_pending_state() in dm_wait_for_completion()
  dm: rename task state function arguments
  dm: add two lockdep_assert_held() statements
  dm rq: simplify dm_old_stop_queue()
  dm mpath: check if path's request_queue is dying in activate_path()
  ...

1 files changed, 162 insertions, 0 deletions

diff --git a/drivers/md/persistent-data/dm-btree.c b/drivers/md/persistent-data/dm-btree.c
index 2cc1877804c2..20a40329d84a 100644
--- a/drivers/md/persistent-data/dm-btree.c
+++ b/drivers/md/persistent-data/dm-btree.c
@@ -994,3 +994,165 @@ int dm_btree_walk(struct dm_btree_info *info, dm_block_t root,
 	return walk_node(info, root, fn, context);
 }
 EXPORT_SYMBOL_GPL(dm_btree_walk);
+
+/*----------------------------------------------------------------*/
+
+static void prefetch_values(struct dm_btree_cursor *c)
+{
+	unsigned i, nr;
+	__le64 value_le;
+	struct cursor_node *n = c->nodes + c->depth - 1;
+	struct btree_node *bn = dm_block_data(n->b);
+	struct dm_block_manager *bm = dm_tm_get_bm(c->info->tm);
+
+	BUG_ON(c->info->value_type.size != sizeof(value_le));
+
+	nr = le32_to_cpu(bn->header.nr_entries);
+	for (i = 0; i < nr; i++) {
+		memcpy(&value_le, value_ptr(bn, i), sizeof(value_le));
+		dm_bm_prefetch(bm, le64_to_cpu(value_le));
+	}
+}
+
+static bool leaf_node(struct dm_btree_cursor *c)
+{
+	struct cursor_node *n = c->nodes + c->depth - 1;
+	struct btree_node *bn = dm_block_data(n->b);
+
+	return le32_to_cpu(bn->header.flags) & LEAF_NODE;
+}
+
+static int push_node(struct dm_btree_cursor *c, dm_block_t b)
+{
+	int r;
+	struct cursor_node *n = c->nodes + c->depth;
+
+	if (c->depth >= DM_BTREE_CURSOR_MAX_DEPTH - 1) {
+		DMERR("couldn't push cursor node, stack depth too high");
+		return -EINVAL;
+	}
+
+	r = bn_read_lock(c->info, b, &n->b);
+	if (r)
+		return r;
+
+	n->index = 0;
+	c->depth++;
+
+	if (c->prefetch_leaves || !leaf_node(c))
+		prefetch_values(c);
+
+	return 0;
+}
+
+static void pop_node(struct dm_btree_cursor *c)
+{
+	c->depth--;
+	unlock_block(c->info, c->nodes[c->depth].b);
+}
+
+static int inc_or_backtrack(struct dm_btree_cursor *c)
+{
+	struct cursor_node *n;
+	struct btree_node *bn;
+
+	for (;;) {
+		if (!c->depth)
+			return -ENODATA;
+
+		n = c->nodes + c->depth - 1;
+		bn = dm_block_data(n->b);
+
+		n->index++;
+		if (n->index < le32_to_cpu(bn->header.nr_entries))
+			break;
+
+		pop_node(c);
+	}
+
+	return 0;
+}
+
+static int find_leaf(struct dm_btree_cursor *c)
+{
+	int r = 0;
+	struct cursor_node *n;
+	struct btree_node *bn;
+	__le64 value_le;
+
+	for (;;) {
+		n = c->nodes + c->depth - 1;
+		bn = dm_block_data(n->b);
+
+		if (le32_to_cpu(bn->header.flags) & LEAF_NODE)
+			break;
+
+		memcpy(&value_le, value_ptr(bn, n->index), sizeof(value_le));
+		r = push_node(c, le64_to_cpu(value_le));
+		if (r) {
+			DMERR("push_node failed");
+			break;
+		}
+	}
+
+	if (!r && (le32_to_cpu(bn->header.nr_entries) == 0))
+		return -ENODATA;
+
+	return r;
+}
+
+int dm_btree_cursor_begin(struct dm_btree_info *info, dm_block_t root,
+			  bool prefetch_leaves, struct dm_btree_cursor *c)
+{
+	int r;
+
+	c->info = info;
+	c->root = root;
+	c->depth = 0;
+	c->prefetch_leaves = prefetch_leaves;
+
+	r = push_node(c, root);
+	if (r)
+		return r;
+
+	return find_leaf(c);
+}
+EXPORT_SYMBOL_GPL(dm_btree_cursor_begin);
+
+void dm_btree_cursor_end(struct dm_btree_cursor *c)
+{
+	while (c->depth)
+		pop_node(c);
+}
+EXPORT_SYMBOL_GPL(dm_btree_cursor_end);
+
+int dm_btree_cursor_next(struct dm_btree_cursor *c)
+{
+	int r = inc_or_backtrack(c);
+	if (!r) {
+		r = find_leaf(c);
+		if (r)
+			DMERR("find_leaf failed");
+	}
+
+	return r;
+}
+EXPORT_SYMBOL_GPL(dm_btree_cursor_next);
+
+int dm_btree_cursor_get_value(struct dm_btree_cursor *c, uint64_t *key, void *value_le)
+{
+	if (c->depth) {
+		struct cursor_node *n = c->nodes + c->depth - 1;
+		struct btree_node *bn = dm_block_data(n->b);
+
+		if (le32_to_cpu(bn->header.flags) & INTERNAL_NODE)
+			return -EINVAL;
+
+		*key = le64_to_cpu(*key_ptr(bn, n->index));
+		memcpy(value_le, value_ptr(bn, n->index), c->info->value_type.size);
+		return 0;
+
+	} else
+		return -ENODATA;
+}
+EXPORT_SYMBOL_GPL(dm_btree_cursor_get_value);