btrfs: backref: rename and move finish_upper_links() (fc997ed0) · Commits · 戴 / test

fs/btrfs/backref.c

+106 −0

Original line number	Diff line number	Diff line
		@@ -2830,6 +2830,7 @@ out:
		*
		* NOTE: Even if the function returned 0, @cur is not yet cached as its upper
		* links aren't yet bi-directional. Needs to finish such links.
		* Use btrfs_backref_finish_upper_links() to finish such linkage.
		*
		* @path: Released path for indirect tree backref lookup
		* @iter: Released backref iter for extent tree search
		@@ -2957,3 +2958,108 @@ out:
		btrfs_backref_iter_release(iter);
		return ret;
		}

		/*
		* Finish the upwards linkage created by btrfs_backref_add_tree_node()
		*/
		int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache,
		struct btrfs_backref_node *start)
		{
		struct list_head *useless_node = &cache->useless_node;
		struct btrfs_backref_edge *edge;
		struct rb_node *rb_node;
		LIST_HEAD(pending_edge);

		ASSERT(start->checked);

		/* Insert this node to cache if it's not COW-only */
		if (!start->cowonly) {
		rb_node = rb_simple_insert(&cache->rb_root, start->bytenr,
		&start->rb_node);
		if (rb_node)
		btrfs_backref_panic(cache->fs_info, start->bytenr,
		-EEXIST);
		list_add_tail(&start->lower, &cache->leaves);
		}

		/*
		* Use breadth first search to iterate all related edges.
		*
		* The starting points are all the edges of this node
		*/
		list_for_each_entry(edge, &start->upper, list[LOWER])
		list_add_tail(&edge->list[UPPER], &pending_edge);

		while (!list_empty(&pending_edge)) {
		struct btrfs_backref_node *upper;
		struct btrfs_backref_node *lower;
		struct rb_node *rb_node;

		edge = list_first_entry(&pending_edge,
		struct btrfs_backref_edge, list[UPPER]);
		list_del_init(&edge->list[UPPER]);
		upper = edge->node[UPPER];
		lower = edge->node[LOWER];

		/* Parent is detached, no need to keep any edges */
		if (upper->detached) {
		list_del(&edge->list[LOWER]);
		btrfs_backref_free_edge(cache, edge);

		/* Lower node is orphan, queue for cleanup */
		if (list_empty(&lower->upper))
		list_add(&lower->list, useless_node);
		continue;
		}

		/*
		* All new nodes added in current build_backref_tree() haven't
		* been linked to the cache rb tree.
		* So if we have upper->rb_node populated, this means a cache
		* hit. We only need to link the edge, as @upper and all its
		* parents have already been linked.
		*/
		if (!RB_EMPTY_NODE(&upper->rb_node)) {
		if (upper->lowest) {
		list_del_init(&upper->lower);
		upper->lowest = 0;
		}

		list_add_tail(&edge->list[UPPER], &upper->lower);
		continue;
		}

		/* Sanity check, we shouldn't have any unchecked nodes */
		if (!upper->checked) {
		ASSERT(0);
		return -EUCLEAN;
		}

		/* Sanity check, COW-only node has non-COW-only parent */
		if (start->cowonly != upper->cowonly) {
		ASSERT(0);
		return -EUCLEAN;
		}

		/* Only cache non-COW-only (subvolume trees) tree blocks */
		if (!upper->cowonly) {
		rb_node = rb_simple_insert(&cache->rb_root, upper->bytenr,
		&upper->rb_node);
		if (rb_node) {
		btrfs_backref_panic(cache->fs_info,
		upper->bytenr, -EEXIST);
		return -EUCLEAN;
		}
		}

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

		/*
		* Also queue all the parent edges of this uncached node
		* to finish the upper linkage
		*/
		list_for_each_entry(edge, &upper->upper, list[LOWER])
		list_add_tail(&edge->list[UPPER], &pending_edge);
		}
		return 0;
		}

fs/btrfs/backref.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -369,4 +369,7 @@ int btrfs_backref_add_tree_node(struct btrfs_backref_cache *cache,
		struct btrfs_key *node_key,
		struct btrfs_backref_node *cur);

		int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache,
		struct btrfs_backref_node *start);

		#endif

fs/btrfs/relocation.c

+1 −115

Original line number	Diff line number	Diff line
		@@ -377,120 +377,6 @@ static struct btrfs_root read_fs_root(struct btrfs_fs_info fs_info,
		return btrfs_get_fs_root(fs_info, &key, false);
		}

		/*
		* In handle_one_tree_backref(), we have only linked the lower node to the edge,
		* but the upper node hasn't been linked to the edge.
		* This means we can only iterate through btrfs_backref_node::upper to reach
		* parent edges, but not through btrfs_backref_node::lower to reach children
		* edges.
		*
		* This function will finish the btrfs_backref_node::lower to related edges,
		* so that backref cache can be bi-directionally iterated.
		*
		* Also, this will add the nodes to backref cache for the next run.
		*/
		static int finish_upper_links(struct btrfs_backref_cache *cache,
		struct btrfs_backref_node *start)
		{
		struct list_head *useless_node = &cache->useless_node;
		struct btrfs_backref_edge *edge;
		struct rb_node *rb_node;
		LIST_HEAD(pending_edge);

		ASSERT(start->checked);

		/* Insert this node to cache if it's not COW-only */
		if (!start->cowonly) {
		rb_node = rb_simple_insert(&cache->rb_root, start->bytenr,
		&start->rb_node);
		if (rb_node)
		btrfs_backref_panic(cache->fs_info, start->bytenr,
		-EEXIST);
		list_add_tail(&start->lower, &cache->leaves);
		}

		/*
		* Use breadth first search to iterate all related edges.
		*
		* The starting points are all the edges of this node
		*/
		list_for_each_entry(edge, &start->upper, list[LOWER])
		list_add_tail(&edge->list[UPPER], &pending_edge);

		while (!list_empty(&pending_edge)) {
		struct btrfs_backref_node *upper;
		struct btrfs_backref_node *lower;
		struct rb_node *rb_node;

		edge = list_first_entry(&pending_edge,
		struct btrfs_backref_edge, list[UPPER]);
		list_del_init(&edge->list[UPPER]);
		upper = edge->node[UPPER];
		lower = edge->node[LOWER];

		/* Parent is detached, no need to keep any edges */
		if (upper->detached) {
		list_del(&edge->list[LOWER]);
		btrfs_backref_free_edge(cache, edge);

		/* Lower node is orphan, queue for cleanup */
		if (list_empty(&lower->upper))
		list_add(&lower->list, useless_node);
		continue;
		}

		/*
		* All new nodes added in current build_backref_tree() haven't
		* been linked to the cache rb tree.
		* So if we have upper->rb_node populated, this means a cache
		* hit. We only need to link the edge, as @upper and all its
		* parent have already been linked.
		*/
		if (!RB_EMPTY_NODE(&upper->rb_node)) {
		if (upper->lowest) {
		list_del_init(&upper->lower);
		upper->lowest = 0;
		}

		list_add_tail(&edge->list[UPPER], &upper->lower);
		continue;
		}

		/* Sanity check, we shouldn't have any unchecked nodes */
		if (!upper->checked) {
		ASSERT(0);
		return -EUCLEAN;
		}

		/* Sanity check, COW-only node has non-COW-only parent */
		if (start->cowonly != upper->cowonly) {
		ASSERT(0);
		return -EUCLEAN;
		}

		/* Only cache non-COW-only (subvolume trees) tree blocks */
		if (!upper->cowonly) {
		rb_node = rb_simple_insert(&cache->rb_root, upper->bytenr,
		&upper->rb_node);
		if (rb_node) {
		btrfs_backref_panic(cache->fs_info,
		upper->bytenr, -EEXIST);
		return -EUCLEAN;
		}
		}

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

		/*
		* Also queue all the parent edges of this uncached node to
		* finish the upper linkage
		*/
		list_for_each_entry(edge, &upper->upper, list[LOWER])
		list_add_tail(&edge->list[UPPER], &pending_edge);
		}
		return 0;
		}

		/*
		* For useless nodes, do two major clean ups:
		*
		@@ -634,7 +520,7 @@ static noinline_for_stack struct btrfs_backref_node *build_backref_tree(
		} while (edge);

		/* Finish the upper linkage of newly added edges/nodes */
		ret = finish_upper_links(cache, node);
		ret = btrfs_backref_finish_upper_links(cache, node);
		if (ret < 0) {
		err = ret;
		goto out;

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