Commit e3d03965 authored by Liu Bo's avatar Liu Bo Committed by David Sterba
Browse files

Btrfs: delayed-refs: use rb_first_cached for ref_tree 



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

Functions manipulating href->ref_tree need to get the first entry, this
converts href->ref_tree to use rb_first_cached().

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 5c9d028b

fs/btrfs/backref.c

+1 −1
Original line number Diff line number Diff line
@@ -769,7 +769,7 @@ static int add_delayed_refs(const struct btrfs_fs_info *fs_info, 
		btrfs_disk_key_to_cpu(&tmp_op_key, &extent_op->key);



	spin_lock(&head->lock);

	for (n = rb_first(&head->ref_tree); n; n = rb_next(n)) {

	for (n = rb_first_cached(&head->ref_tree); n; n = rb_next(n)) {

		node = rb_entry(n, struct btrfs_delayed_ref_node,

				ref_node);

		if (node->seq > seq)

fs/btrfs/delayed-ref.c

+14 −10
Original line number Diff line number Diff line
@@ -133,13 +133,14 @@ static struct btrfs_delayed_ref_head *htree_insert(struct rb_root_cached *root, 
	return NULL;

}



static struct btrfs_delayed_ref_node* tree_insert(struct rb_root *root,

static struct btrfs_delayed_ref_node* tree_insert(struct rb_root_cached *root,

		struct btrfs_delayed_ref_node *ins)

{

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

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

	struct rb_node *node = &ins->ref_node;

	struct rb_node *parent_node = NULL;

	struct btrfs_delayed_ref_node *entry;

	bool leftmost = true;



	while (*p) {

		int comp;
@@ -148,16 +149,18 @@ static struct btrfs_delayed_ref_node* tree_insert(struct rb_root *root, 
		entry = rb_entry(parent_node, struct btrfs_delayed_ref_node,

				 ref_node);

		comp = comp_refs(ins, entry, true);

		if (comp < 0)

		if (comp < 0) {

			p = &(*p)->rb_left;

		else if (comp > 0)

		} else if (comp > 0) {

			p = &(*p)->rb_right;

		else

			leftmost = false;

		} else {

			return entry;

		}

	}



	rb_link_node(node, parent_node, p);

	rb_insert_color(node, root);

	rb_insert_color_cached(node, root, leftmost);

	return NULL;

}
@@ -231,7 +234,7 @@ static inline void drop_delayed_ref(struct btrfs_trans_handle *trans, 
				    struct btrfs_delayed_ref_node *ref)

{

	lockdep_assert_held(&head->lock);

	rb_erase(&ref->ref_node, &head->ref_tree);

	rb_erase_cached(&ref->ref_node, &head->ref_tree);

	RB_CLEAR_NODE(&ref->ref_node);

	if (!list_empty(&ref->add_list))

		list_del(&ref->add_list);
@@ -300,7 +303,7 @@ void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans, 


	lockdep_assert_held(&head->lock);



	if (RB_EMPTY_ROOT(&head->ref_tree))

	if (RB_EMPTY_ROOT(&head->ref_tree.rb_root))

		return;



	/* We don't have too many refs to merge for data. */
@@ -318,7 +321,8 @@ void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans, 
	spin_unlock(&fs_info->tree_mod_seq_lock);



again:

	for (node = rb_first(&head->ref_tree); node; node = rb_next(node)) {

	for (node = rb_first_cached(&head->ref_tree); node;

	     node = rb_next(node)) {

		ref = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);

		if (seq && ref->seq >= seq)

			continue;
@@ -573,7 +577,7 @@ static void init_delayed_ref_head(struct btrfs_delayed_ref_head *head_ref, 
	head_ref->must_insert_reserved = must_insert_reserved;

	head_ref->is_data = is_data;

	head_ref->is_system = is_system;

	head_ref->ref_tree = RB_ROOT;

	head_ref->ref_tree = RB_ROOT_CACHED;

	INIT_LIST_HEAD(&head_ref->ref_add_list);

	RB_CLEAR_NODE(&head_ref->href_node);

	head_ref->processing = 0;

fs/btrfs/delayed-ref.h

+1 −1
Original line number Diff line number Diff line
@@ -79,7 +79,7 @@ struct btrfs_delayed_ref_head { 
	struct mutex mutex;



	spinlock_t lock;

	struct rb_root ref_tree;

	struct rb_root_cached ref_tree;

	/* accumulate add BTRFS_ADD_DELAYED_REF nodes to this ref_add_list. */

	struct list_head ref_add_list;

fs/btrfs/disk-io.c

+2 −2
Original line number Diff line number Diff line
@@ -4221,11 +4221,11 @@ static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans, 
			continue;

		}

		spin_lock(&head->lock);

		while ((n = rb_first(&head->ref_tree)) != NULL) {

		while ((n = rb_first_cached(&head->ref_tree)) != NULL) {

			ref = rb_entry(n, struct btrfs_delayed_ref_node,

				       ref_node);

			ref->in_tree = 0;

			rb_erase(&ref->ref_node, &head->ref_tree);

			rb_erase_cached(&ref->ref_node, &head->ref_tree);

			RB_CLEAR_NODE(&ref->ref_node);

			if (!list_empty(&ref->add_list))

				list_del(&ref->add_list);

fs/btrfs/extent-tree.c

+7 −6
Original line number Diff line number Diff line
@@ -2374,7 +2374,7 @@ select_delayed_ref(struct btrfs_delayed_ref_head *head) 
{

	struct btrfs_delayed_ref_node *ref;



	if (RB_EMPTY_ROOT(&head->ref_tree))

	if (RB_EMPTY_ROOT(&head->ref_tree.rb_root))

		return NULL;



	/*
@@ -2387,7 +2387,7 @@ select_delayed_ref(struct btrfs_delayed_ref_head *head) 
		return list_first_entry(&head->ref_add_list,

				struct btrfs_delayed_ref_node, add_list);



	ref = rb_entry(rb_first(&head->ref_tree),

	ref = rb_entry(rb_first_cached(&head->ref_tree),

		       struct btrfs_delayed_ref_node, ref_node);

	ASSERT(list_empty(&ref->add_list));

	return ref;
@@ -2448,7 +2448,7 @@ static int cleanup_ref_head(struct btrfs_trans_handle *trans, 
	spin_unlock(&head->lock);

	spin_lock(&delayed_refs->lock);

	spin_lock(&head->lock);

	if (!RB_EMPTY_ROOT(&head->ref_tree) || head->extent_op) {

	if (!RB_EMPTY_ROOT(&head->ref_tree.rb_root) || head->extent_op) {

		spin_unlock(&head->lock);

		spin_unlock(&delayed_refs->lock);

		return 1;
@@ -2597,7 +2597,7 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans, 


		actual_count++;

		ref->in_tree = 0;

		rb_erase(&ref->ref_node, &locked_ref->ref_tree);

		rb_erase_cached(&ref->ref_node, &locked_ref->ref_tree);

		RB_CLEAR_NODE(&ref->ref_node);

		if (!list_empty(&ref->add_list))

			list_del(&ref->add_list);
@@ -3040,7 +3040,8 @@ static noinline int check_delayed_ref(struct btrfs_root *root, 
	 * XXX: We should replace this with a proper search function in the

	 * future.

	 */

	for (node = rb_first(&head->ref_tree); node; node = rb_next(node)) {

	for (node = rb_first_cached(&head->ref_tree); node;

	     node = rb_next(node)) {

		ref = rb_entry(node, struct btrfs_delayed_ref_node, ref_node);

		/* If it's a shared ref we know a cross reference exists */

		if (ref->type != BTRFS_EXTENT_DATA_REF_KEY) {
@@ -6908,7 +6909,7 @@ static noinline int check_ref_cleanup(struct btrfs_trans_handle *trans, 
		goto out_delayed_unlock;



	spin_lock(&head->lock);

	if (!RB_EMPTY_ROOT(&head->ref_tree))

	if (!RB_EMPTY_ROOT(&head->ref_tree.rb_root))

		goto out;



	if (head->extent_op) {

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