Commit 0097422c authored by Josef Bacik's avatar Josef Bacik Committed by David Sterba
Browse files

btrfs: remove clone_backref_node() from relocation 



Since we no longer maintain backref cache across transactions, and this
is only called when we're creating the reloc root for a newly created
snapshot in the transaction critical section, we will end up doing a
bunch of work that will just get thrown away when we start the
transaction in the relocation loop.  Delete this code as it no longer
does anything for us.

Reviewed-by: default avatarBoris Burkov <boris@bur.io>
Signed-off-by: default avatarJosef Bacik <josef@toxicpanda.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 551d04a3

fs/btrfs/relocation.c

+1 −90
Original line number Diff line number Diff line
@@ -469,92 +469,6 @@ static noinline_for_stack struct btrfs_backref_node *build_backref_tree( 
	return node;

}



/*

 * helper to add backref node for the newly created snapshot.

 * the backref node is created by cloning backref node that

 * corresponds to root of source tree

 */

static int clone_backref_node(struct btrfs_trans_handle *trans,

			      struct reloc_control *rc,

			      const struct btrfs_root *src,

			      struct btrfs_root *dest)

{

	struct btrfs_root *reloc_root = src->reloc_root;

	struct btrfs_backref_cache *cache = &rc->backref_cache;

	struct btrfs_backref_node *node = NULL;

	struct btrfs_backref_node *new_node;

	struct btrfs_backref_edge *edge;

	struct btrfs_backref_edge *new_edge;

	struct rb_node *rb_node;



	rb_node = rb_simple_search(&cache->rb_root, src->commit_root->start);

	if (rb_node) {

		node = rb_entry(rb_node, struct btrfs_backref_node, rb_node);

		if (node->detached)

			node = NULL;

		else

			BUG_ON(node->new_bytenr != reloc_root->node->start);

	}



	if (!node) {

		rb_node = rb_simple_search(&cache->rb_root,

					   reloc_root->commit_root->start);

		if (rb_node) {

			node = rb_entry(rb_node, struct btrfs_backref_node,

					rb_node);

			BUG_ON(node->detached);

		}

	}



	if (!node)

		return 0;



	new_node = btrfs_backref_alloc_node(cache, dest->node->start,

					    node->level);

	if (!new_node)

		return -ENOMEM;



	new_node->lowest = node->lowest;

	new_node->checked = 1;

	new_node->root = btrfs_grab_root(dest);

	ASSERT(new_node->root);



	if (!node->lowest) {

		list_for_each_entry(edge, &node->lower, list[UPPER]) {

			new_edge = btrfs_backref_alloc_edge(cache);

			if (!new_edge)

				goto fail;



			btrfs_backref_link_edge(new_edge, edge->node[LOWER],

						new_node, LINK_UPPER);

		}

	} else {

		list_add_tail(&new_node->lower, &cache->leaves);

	}



	rb_node = rb_simple_insert(&cache->rb_root, new_node->bytenr,

				   &new_node->rb_node);

	if (rb_node)

		btrfs_backref_panic(trans->fs_info, new_node->bytenr, -EEXIST);



	if (!new_node->lowest) {

		list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {

			list_add_tail(&new_edge->list[LOWER],

				      &new_edge->node[LOWER]->upper);

		}

	}

	return 0;

fail:

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

		new_edge = list_entry(new_node->lower.next,

				      struct btrfs_backref_edge, list[UPPER]);

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

		btrfs_backref_free_edge(cache, new_edge);

	}

	btrfs_backref_free_node(cache, new_node);

	return -ENOMEM;

}



/*

 * helper to add 'address of tree root -> reloc tree' mapping

 */
@@ -4485,10 +4399,7 @@ int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans, 
		return ret;

	}

	new_root->reloc_root = btrfs_grab_root(reloc_root);



	if (rc->create_reloc_tree)

		ret = clone_backref_node(trans, rc, root, reloc_root);

	return ret;

	return 0;

}



/*