Commit 07e1ce09 authored by Liu Bo's avatar Liu Bo Committed by David Sterba
Browse files

Btrfs: extent_map: use rb_first_cached 



rb_first_cached() trades an extra pointer "leftmost" for doing the
same job as rb_first() but in O(1).

As evict_inode_truncate_pages() removes all extent mapping by always
looking for the first rb entry, it's helpful to use rb_first_cached
instead.

For more details about the optimization see patch "Btrfs: delayed-refs:
use rb_first_cached for href_root".

Tested-by: default avatarHolger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: default avatarLiu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 03a1d4c8

fs/btrfs/extent_map.c

+15 −12
Original line number Diff line number Diff line
@@ -34,7 +34,7 @@ void __cold extent_map_exit(void) 
 */

void extent_map_tree_init(struct extent_map_tree *tree)

{

	tree->map = RB_ROOT;

	tree->map = RB_ROOT_CACHED;

	INIT_LIST_HEAD(&tree->modified_extents);

	rwlock_init(&tree->lock);

}
@@ -90,25 +90,28 @@ static u64 range_end(u64 start, u64 len) 
	return start + len;

}



static int tree_insert(struct rb_root *root, struct extent_map *em)

static int tree_insert(struct rb_root_cached *root, struct extent_map *em)

{

	struct rb_node **p = &root->rb_node;

	struct rb_node **p = &root->rb_root.rb_node;

	struct rb_node *parent = NULL;

	struct extent_map *entry = NULL;

	struct rb_node *orig_parent = NULL;

	u64 end = range_end(em->start, em->len);

	bool leftmost = true;



	while (*p) {

		parent = *p;

		entry = rb_entry(parent, struct extent_map, rb_node);



		if (em->start < entry->start)

		if (em->start < entry->start) {

			p = &(*p)->rb_left;

		else if (em->start >= extent_map_end(entry))

		} else if (em->start >= extent_map_end(entry)) {

			p = &(*p)->rb_right;

		else

			leftmost = false;

		} else {

			return -EEXIST;

		}

	}



	orig_parent = parent;

	while (parent && em->start >= extent_map_end(entry)) {
@@ -130,7 +133,7 @@ static int tree_insert(struct rb_root *root, struct extent_map *em) 
			return -EEXIST;



	rb_link_node(&em->rb_node, orig_parent, p);

	rb_insert_color(&em->rb_node, root);

	rb_insert_color_cached(&em->rb_node, root, leftmost);

	return 0;

}
@@ -242,7 +245,7 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em) 
			em->mod_start = merge->mod_start;

			em->generation = max(em->generation, merge->generation);



			rb_erase(&merge->rb_node, &tree->map);

			rb_erase_cached(&merge->rb_node, &tree->map);

			RB_CLEAR_NODE(&merge->rb_node);

			free_extent_map(merge);

		}
@@ -254,7 +257,7 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em) 
	if (rb && mergable_maps(em, merge)) {

		em->len += merge->len;

		em->block_len += merge->block_len;

		rb_erase(&merge->rb_node, &tree->map);

		rb_erase_cached(&merge->rb_node, &tree->map);

		RB_CLEAR_NODE(&merge->rb_node);

		em->mod_len = (merge->mod_start + merge->mod_len) - em->mod_start;

		em->generation = max(em->generation, merge->generation);
@@ -367,7 +370,7 @@ __lookup_extent_mapping(struct extent_map_tree *tree, 
	struct rb_node *next = NULL;

	u64 end = range_end(start, len);



	rb_node = __tree_search(&tree->map, start, &prev, &next);

	rb_node = __tree_search(&tree->map.rb_root, start, &prev, &next);

	if (!rb_node) {

		if (prev)

			rb_node = prev;
@@ -431,7 +434,7 @@ struct extent_map *search_extent_mapping(struct extent_map_tree *tree, 
void remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)

{

	WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));

	rb_erase(&em->rb_node, &tree->map);

	rb_erase_cached(&em->rb_node, &tree->map);

	if (!test_bit(EXTENT_FLAG_LOGGING, &em->flags))

		list_del_init(&em->list);

	RB_CLEAR_NODE(&em->rb_node);
@@ -446,7 +449,7 @@ void replace_extent_mapping(struct extent_map_tree *tree, 
	ASSERT(extent_map_in_tree(cur));

	if (!test_bit(EXTENT_FLAG_LOGGING, &cur->flags))

		list_del_init(&cur->list);

	rb_replace_node(&cur->rb_node, &new->rb_node, &tree->map);

	rb_replace_node_cached(&cur->rb_node, &new->rb_node, &tree->map);

	RB_CLEAR_NODE(&cur->rb_node);



	setup_extent_mapping(tree, new, modified);

fs/btrfs/extent_map.h

+1 −1
Original line number Diff line number Diff line
@@ -49,7 +49,7 @@ struct extent_map { 
};



struct extent_map_tree {

	struct rb_root map;

	struct rb_root_cached map;

	struct list_head modified_extents;

	rwlock_t lock;

};

fs/btrfs/inode.c

+2 −2
Original line number Diff line number Diff line
@@ -5222,10 +5222,10 @@ static void evict_inode_truncate_pages(struct inode *inode) 
	truncate_inode_pages_final(&inode->i_data);



	write_lock(&map_tree->lock);

	while (!RB_EMPTY_ROOT(&map_tree->map)) {

	while (!RB_EMPTY_ROOT(&map_tree->map.rb_root)) {

		struct extent_map *em;



		node = rb_first(&map_tree->map);

		node = rb_first_cached(&map_tree->map);

		em = rb_entry(node, struct extent_map, rb_node);

		clear_bit(EXTENT_FLAG_PINNED, &em->flags);

		clear_bit(EXTENT_FLAG_LOGGING, &em->flags);

fs/btrfs/tests/extent-map-tests.c

+2 −2
Original line number Diff line number Diff line
@@ -12,8 +12,8 @@ static void free_extent_map_tree(struct extent_map_tree *em_tree) 
	struct extent_map *em;

	struct rb_node *node;



	while (!RB_EMPTY_ROOT(&em_tree->map)) {

		node = rb_first(&em_tree->map);

	while (!RB_EMPTY_ROOT(&em_tree->map.rb_root)) {

		node = rb_first_cached(&em_tree->map);

		em = rb_entry(node, struct extent_map, rb_node);

		remove_extent_mapping(em_tree, em);

fs/btrfs/volumes.c

+2 −2
Original line number Diff line number Diff line
@@ -1613,7 +1613,7 @@ static u64 find_next_chunk(struct btrfs_fs_info *fs_info) 


	em_tree = &fs_info->mapping_tree.map_tree;

	read_lock(&em_tree->lock);

	n = rb_last(&em_tree->map);

	n = rb_last(&em_tree->map.rb_root);

	if (n) {

		em = rb_entry(n, struct extent_map, rb_node);

		ret = em->start + em->len;
@@ -7445,7 +7445,7 @@ static int verify_chunk_dev_extent_mapping(struct btrfs_fs_info *fs_info) 
	int ret = 0;



	read_lock(&em_tree->lock);

	for (node = rb_first(&em_tree->map); node; node = rb_next(node)) {

	for (node = rb_first_cached(&em_tree->map); node; node = rb_next(node)) {

		em = rb_entry(node, struct extent_map, rb_node);

		if (em->map_lookup->num_stripes !=

		    em->map_lookup->verified_stripes) {

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