Commit 63ffc1f7 authored by Filipe Manana's avatar Filipe Manana Committed by David Sterba
Browse files

btrfs: make tree iteration in extent_io_tree_release() more efficient 



Currently extent_io_tree_release() is a loop that keeps getting the first
node in the io tree, using rb_first() which is a loop that gets to the
leftmost node of the rbtree, and then for each node it calls rb_erase(),
which often requires rebalancing the rbtree.

We can make this more efficient by using
rbtree_postorder_for_each_entry_safe() to free each node without having
to delete it from the rbtree and without looping to get the first node.

Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent df2a8e70

fs/btrfs/extent-io-tree.c

+13 −8
Original line number Diff line number Diff line
@@ -114,14 +114,15 @@ void extent_io_tree_init(struct btrfs_fs_info *fs_info, 
 */

void extent_io_tree_release(struct extent_io_tree *tree)

{

	spin_lock(&tree->lock);

	while (!RB_EMPTY_ROOT(&tree->state)) {

		struct rb_node *node;

	struct rb_root root;

	struct extent_state *state;

	struct extent_state *tmp;



		node = rb_first(&tree->state);

		state = rb_entry(node, struct extent_state, rb_node);

		rb_erase(&state->rb_node, &tree->state);

	spin_lock(&tree->lock);

	root = tree->state;

	tree->state = RB_ROOT;

	rbtree_postorder_for_each_entry_safe(state, tmp, &root, rb_node) {

		/* Clear node to keep free_extent_state() happy. */

		RB_CLEAR_NODE(&state->rb_node);

		ASSERT(!(state->state & EXTENT_LOCKED));

		/*
@@ -131,9 +132,13 @@ void extent_io_tree_release(struct extent_io_tree *tree) 
		 */

		ASSERT(!waitqueue_active(&state->wq));

		free_extent_state(state);



		cond_resched_lock(&tree->lock);

	}

	/*

	 * Should still be empty even after a reschedule, no other task should

	 * be accessing the tree anymore.

	 */

	ASSERT(RB_EMPTY_ROOT(&tree->state));

	spin_unlock(&tree->lock);

}