Commit 84780289 authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: reloc: add backref_cache::pending_edge and backref_cache::useless_node 



These two new members will act the same as the existing local lists,
@useless and @list in build_backref_tree().

Currently build_backref_tree() is only executed serially, thus moving
such local list into backref_cache is still safe.

Also since we're here, use list_first_entry() to replace a lot of
list_entry() calls after !list_empty().

Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 9569cc20

fs/btrfs/relocation.c

+46 −28
Original line number Diff line number Diff line
@@ -158,6 +158,12 @@ struct backref_cache { 


	int nr_nodes;

	int nr_edges;



	/* The list of unchecked backref edges during backref cache build */

	struct list_head pending_edge;



	/* The list of useless backref nodes during backref cache build */

	struct list_head useless_node;

};



/*
@@ -269,6 +275,8 @@ static void backref_cache_init(struct backref_cache *cache) 
	INIT_LIST_HEAD(&cache->changed);

	INIT_LIST_HEAD(&cache->detached);

	INIT_LIST_HEAD(&cache->leaves);

	INIT_LIST_HEAD(&cache->pending_edge);

	INIT_LIST_HEAD(&cache->useless_node);

}



static void backref_cache_cleanup(struct backref_cache *cache)
@@ -292,6 +300,8 @@ static void backref_cache_cleanup(struct backref_cache *cache) 


	for (i = 0; i < BTRFS_MAX_LEVEL; i++)

		ASSERT(list_empty(&cache->pending[i]));

	ASSERT(list_empty(&cache->pending_edge));

	ASSERT(list_empty(&cache->useless_node));

	ASSERT(list_empty(&cache->changed));

	ASSERT(list_empty(&cache->detached));

	ASSERT(RB_EMPTY_ROOT(&cache->rb_root));
@@ -699,8 +709,6 @@ struct backref_node *build_backref_tree(struct reloc_control *rc, 
	struct backref_node *exist = NULL;

	struct backref_edge *edge;

	struct rb_node *rb_node;

	LIST_HEAD(list); /* Pending edge list, upper node needs to be checked */

	LIST_HEAD(useless);

	int cowonly;

	int ret;

	int err = 0;
@@ -764,7 +772,7 @@ again: 
		 * check its backrefs

		 */

		if (!exist->checked)

			list_add_tail(&edge->list[UPPER], &list);

			list_add_tail(&edge->list[UPPER], &cache->pending_edge);

	} else {

		exist = NULL;

	}
@@ -842,7 +850,8 @@ again: 
				 *  backrefs for the upper level block isn't

				 *  cached, add the block to pending list

				 */

				list_add_tail(&edge->list[UPPER], &list);

				list_add_tail(&edge->list[UPPER],

					      &cache->pending_edge);

			} else {

				upper = rb_entry(rb_node, struct backref_node,

						 rb_node);
@@ -884,7 +893,7 @@ again: 
			       cur->bytenr);

			if (should_ignore_root(root)) {

				btrfs_put_root(root);

				list_add(&cur->list, &useless);

				list_add(&cur->list, &cache->useless_node);

			} else {

				cur->root = root;

			}
@@ -930,7 +939,8 @@ again: 
				       lower->bytenr);

				if (should_ignore_root(root)) {

					btrfs_put_root(root);

					list_add(&lower->list, &useless);

					list_add(&lower->list,

						 &cache->useless_node);

				} else {

					lower->root = root;

				}
@@ -979,7 +989,7 @@ again: 
				if (!upper->checked && need_check) {

					need_check = false;

					list_add_tail(&edge->list[UPPER],

						      &list);

						      &cache->pending_edge);

				} else {

					if (upper->checked)

						need_check = true;
@@ -1017,8 +1027,9 @@ again: 
	WARN_ON(exist);



	/* the pending list isn't empty, take the first block to process */

	if (!list_empty(&list)) {

		edge = list_entry(list.next, struct backref_edge, list[UPPER]);

	if (!list_empty(&cache->pending_edge)) {

		edge = list_first_entry(&cache->pending_edge,

				  struct backref_edge, list[UPPER]);

		list_del_init(&edge->list[UPPER]);

		cur = edge->node[UPPER];

		goto again;
@@ -1039,10 +1050,11 @@ again: 
	}



	list_for_each_entry(edge, &node->upper, list[LOWER])

		list_add_tail(&edge->list[UPPER], &list);

		list_add_tail(&edge->list[UPPER], &cache->pending_edge);



	while (!list_empty(&list)) {

		edge = list_entry(list.next, struct backref_edge, list[UPPER]);

	while (!list_empty(&cache->pending_edge)) {

		edge = list_first_entry(&cache->pending_edge,

				struct backref_edge, list[UPPER]);

		list_del_init(&edge->list[UPPER]);

		upper = edge->node[UPPER];

		if (upper->detached) {
@@ -1050,7 +1062,7 @@ again: 
			lower = edge->node[LOWER];

			free_backref_edge(cache, edge);

			if (list_empty(&lower->upper))

				list_add(&lower->list, &useless);

				list_add(&lower->list, &cache->useless_node);

			continue;

		}
@@ -1090,7 +1102,7 @@ again: 
		list_add_tail(&edge->list[UPPER], &upper->lower);



		list_for_each_entry(edge, &upper->upper, list[LOWER])

			list_add_tail(&edge->list[UPPER], &list);

			list_add_tail(&edge->list[UPPER], &cache->pending_edge);

	}

	/*

	 * process useless backref nodes. backref nodes for tree leaves
@@ -1098,8 +1110,9 @@ again: 
	 * tree blocks are left in the cache to avoid unnecessary backref

	 * lookup.

	 */

	while (!list_empty(&useless)) {

		upper = list_entry(useless.next, struct backref_node, list);

	while (!list_empty(&cache->useless_node)) {

		upper = list_first_entry(&cache->useless_node,

				   struct backref_node, list);

		list_del_init(&upper->list);

		ASSERT(list_empty(&upper->upper));

		if (upper == node)
@@ -1109,7 +1122,7 @@ again: 
			upper->lowest = 0;

		}

		while (!list_empty(&upper->lower)) {

			edge = list_entry(upper->lower.next,

			edge = list_first_entry(&upper->lower,

					  struct backref_edge, list[UPPER]);

			list_del(&edge->list[UPPER]);

			list_del(&edge->list[LOWER]);
@@ -1117,7 +1130,7 @@ again: 
			free_backref_edge(cache, edge);



			if (list_empty(&lower->upper))

				list_add(&lower->list, &useless);

				list_add(&lower->list, &cache->useless_node);

		}

		mark_block_processed(rc, upper);

		if (upper->level > 0) {
@@ -1132,14 +1145,14 @@ out: 
	btrfs_backref_iter_free(iter);

	btrfs_free_path(path);

	if (err) {

		while (!list_empty(&useless)) {

			lower = list_entry(useless.next,

		while (!list_empty(&cache->useless_node)) {

			lower = list_first_entry(&cache->useless_node,

					   struct backref_node, list);

			list_del_init(&lower->list);

		}

		while (!list_empty(&list)) {

			edge = list_first_entry(&list, struct backref_edge,

						list[UPPER]);

		while (!list_empty(&cache->pending_edge)) {

			edge = list_first_entry(&cache->pending_edge,

					struct backref_edge, list[UPPER]);

			list_del(&edge->list[UPPER]);

			list_del(&edge->list[LOWER]);

			lower = edge->node[LOWER];
@@ -1152,20 +1165,21 @@ out: 
			 */

			if (list_empty(&lower->upper) &&

			    RB_EMPTY_NODE(&lower->rb_node))

				list_add(&lower->list, &useless);

				list_add(&lower->list, &cache->useless_node);



			if (!RB_EMPTY_NODE(&upper->rb_node))

				continue;



			/* Add this guy's upper edges to the list to process */

			list_for_each_entry(edge, &upper->upper, list[LOWER])

				list_add_tail(&edge->list[UPPER], &list);

				list_add_tail(&edge->list[UPPER],

					      &cache->pending_edge);

			if (list_empty(&upper->upper))

				list_add(&upper->list, &useless);

				list_add(&upper->list, &cache->useless_node);

		}



		while (!list_empty(&useless)) {

			lower = list_entry(useless.next,

		while (!list_empty(&cache->useless_node)) {

			lower = list_first_entry(&cache->useless_node,

					   struct backref_node, list);

			list_del_init(&lower->list);

			if (lower == node)
@@ -1174,9 +1188,13 @@ out: 
		}



		remove_backref_node(cache, node);

		ASSERT(list_empty(&cache->useless_node) &&

		       list_empty(&cache->pending_edge));

		return ERR_PTR(err);

	}

	ASSERT(!node || !node->detached);

	ASSERT(list_empty(&cache->useless_node) &&

	       list_empty(&cache->pending_edge));

	return node;

}

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