btrfs: temporarily export and move core extent_io_tree tree functions

A lot of the various internals of extent_io_tree call these two
functions for insert or searching the rb tree for entries, so
temporarily export them and then move them to extent-io-tree.c.  We
can't move tree_search() without renaming it, and I don't want to
introduce a bunch of churn just to do that, so move these functions
first and then we can move a few big functions and then the remaining
users of tree_search().

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 107 insertions, 0 deletions

diff --git a/fs/btrfs/extent-io-tree.c b/fs/btrfs/extent-io-tree.c
index b487a9e4aaa7..8dd03ac86d26 100644
--- a/fs/btrfs/extent-io-tree.c
+++ b/fs/btrfs/extent-io-tree.c
@@ -161,6 +161,113 @@ void free_extent_state(struct extent_state *state)
 	}
 }
 
+/*
+ * Search @tree for an entry that contains @offset. Such entry would have
+ * entry->start <= offset && entry->end >= offset.
+ *
+ * @tree:       the tree to search
+ * @offset:     offset that should fall within an entry in @tree
+ * @node_ret:   pointer where new node should be anchored (used when inserting an
+ *	        entry in the tree)
+ * @parent_ret: points to entry which would have been the parent of the entry,
+ *               containing @offset
+ *
+ * Return a pointer to the entry that contains @offset byte address and don't change
+ * @node_ret and @parent_ret.
+ *
+ * If no such entry exists, return pointer to entry that ends before @offset
+ * and fill parameters @node_ret and @parent_ret, ie. does not return NULL.
+ */
+struct rb_node *tree_search_for_insert(struct extent_io_tree *tree, u64 offset,
+				       struct rb_node ***node_ret,
+				       struct rb_node **parent_ret)
+{
+	struct rb_root *root = &tree->state;
+	struct rb_node **node = &root->rb_node;
+	struct rb_node *prev = NULL;
+	struct tree_entry *entry;
+
+	while (*node) {
+		prev = *node;
+		entry = rb_entry(prev, struct tree_entry, rb_node);
+
+		if (offset < entry->start)
+			node = &(*node)->rb_left;
+		else if (offset > entry->end)
+			node = &(*node)->rb_right;
+		else
+			return *node;
+	}
+
+	if (node_ret)
+		*node_ret = node;
+	if (parent_ret)
+		*parent_ret = prev;
+
+	/* Search neighbors until we find the first one past the end */
+	while (prev && offset > entry->end) {
+		prev = rb_next(prev);
+		entry = rb_entry(prev, struct tree_entry, rb_node);
+	}
+
+	return prev;
+}
+
+/*
+ * Search offset in the tree or fill neighbor rbtree node pointers.
+ *
+ * @tree:      the tree to search
+ * @offset:    offset that should fall within an entry in @tree
+ * @next_ret:  pointer to the first entry whose range ends after @offset
+ * @prev_ret:  pointer to the first entry whose range begins before @offset
+ *
+ * Return a pointer to the entry that contains @offset byte address. If no
+ * such entry exists, then return NULL and fill @prev_ret and @next_ret.
+ * Otherwise return the found entry and other pointers are left untouched.
+ */
+struct rb_node *tree_search_prev_next(struct extent_io_tree *tree, u64 offset,
+				      struct rb_node **prev_ret,
+				      struct rb_node **next_ret)
+{
+	struct rb_root *root = &tree->state;
+	struct rb_node **node = &root->rb_node;
+	struct rb_node *prev = NULL;
+	struct rb_node *orig_prev = NULL;
+	struct tree_entry *entry;
+
+	ASSERT(prev_ret);
+	ASSERT(next_ret);
+
+	while (*node) {
+		prev = *node;
+		entry = rb_entry(prev, struct tree_entry, rb_node);
+
+		if (offset < entry->start)
+			node = &(*node)->rb_left;
+		else if (offset > entry->end)
+			node = &(*node)->rb_right;
+		else
+			return *node;
+	}
+
+	orig_prev = prev;
+	while (prev && offset > entry->end) {
+		prev = rb_next(prev);
+		entry = rb_entry(prev, struct tree_entry, rb_node);
+	}
+	*next_ret = prev;
+	prev = orig_prev;
+
+	entry = rb_entry(prev, struct tree_entry, rb_node);
+	while (prev && offset < entry->start) {
+		prev = rb_prev(prev);
+		entry = rb_entry(prev, struct tree_entry, rb_node);
+	}
+	*prev_ret = prev;
+
+	return NULL;
+}
+
 /* Wrappers around set/clear extent bit */
 int set_record_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
 			   u32 bits, struct extent_changeset *changeset)