forked from luck/tmp_suning_uos_patched
btrfs: reloc: refactor useless nodes handling into its own function
This patch will also add some comment for the cleanup. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
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@ -1192,6 +1192,80 @@ static int finish_upper_links(struct backref_cache *cache,
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return 0;
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}
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/*
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* For useless nodes, do two major clean ups:
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*
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* - Cleanup the children edges and nodes
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* If child node is also orphan (no parent) during cleanup, then the child
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* node will also be cleaned up.
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*
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* - Freeing up leaves (level 0), keeps nodes detached
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* For nodes, the node is still cached as "detached"
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*
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* Return false if @node is not in the @useless_nodes list.
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* Return true if @node is in the @useless_nodes list.
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*/
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static bool handle_useless_nodes(struct reloc_control *rc,
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struct backref_node *node)
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{
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struct backref_cache *cache = &rc->backref_cache;
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struct list_head *useless_node = &cache->useless_node;
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bool ret = false;
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while (!list_empty(useless_node)) {
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struct backref_node *cur;
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cur = list_first_entry(useless_node, struct backref_node,
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list);
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list_del_init(&cur->list);
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/* Only tree root nodes can be added to @useless_nodes */
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ASSERT(list_empty(&cur->upper));
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if (cur == node)
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ret = true;
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/* The node is the lowest node */
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if (cur->lowest) {
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list_del_init(&cur->lower);
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cur->lowest = 0;
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}
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/* Cleanup the lower edges */
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while (!list_empty(&cur->lower)) {
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struct backref_edge *edge;
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struct backref_node *lower;
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edge = list_entry(cur->lower.next,
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struct backref_edge, list[UPPER]);
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list_del(&edge->list[UPPER]);
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list_del(&edge->list[LOWER]);
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lower = edge->node[LOWER];
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free_backref_edge(cache, edge);
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/* Child node is also orphan, queue for cleanup */
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if (list_empty(&lower->upper))
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list_add(&lower->list, useless_node);
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}
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/* Mark this block processed for relocation */
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mark_block_processed(rc, cur);
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/*
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* Backref nodes for tree leaves are deleted from the cache.
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* Backref nodes for upper level tree blocks are left in the
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* cache to avoid unnecessary backref lookup.
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*/
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if (cur->level > 0) {
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list_add(&cur->list, &cache->detached);
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cur->detached = 1;
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} else {
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rb_erase(&cur->rb_node, &cache->rb_root);
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free_backref_node(cache, cur);
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}
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}
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return ret;
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}
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/*
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* Build backref tree for a given tree block. Root of the backref tree
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* corresponds the tree block, leaves of the backref tree correspond roots of
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@ -1266,43 +1340,8 @@ static noinline_for_stack struct backref_node *build_backref_tree(
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goto out;
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}
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/*
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* process useless backref nodes. backref nodes for tree leaves
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* are deleted from the cache. backref nodes for upper level
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* tree blocks are left in the cache to avoid unnecessary backref
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* lookup.
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*/
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while (!list_empty(&cache->useless_node)) {
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upper = list_first_entry(&cache->useless_node,
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struct backref_node, list);
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list_del_init(&upper->list);
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ASSERT(list_empty(&upper->upper));
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if (upper == node)
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node = NULL;
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if (upper->lowest) {
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list_del_init(&upper->lower);
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upper->lowest = 0;
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}
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while (!list_empty(&upper->lower)) {
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edge = list_first_entry(&upper->lower,
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struct backref_edge, list[UPPER]);
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list_del(&edge->list[UPPER]);
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list_del(&edge->list[LOWER]);
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lower = edge->node[LOWER];
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free_backref_edge(cache, edge);
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if (list_empty(&lower->upper))
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list_add(&lower->list, &cache->useless_node);
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}
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mark_block_processed(rc, upper);
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if (upper->level > 0) {
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list_add(&upper->list, &cache->detached);
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upper->detached = 1;
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} else {
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rb_erase(&upper->rb_node, &cache->rb_root);
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free_backref_node(cache, upper);
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}
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}
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if (handle_useless_nodes(rc, node))
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node = NULL;
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out:
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btrfs_backref_iter_free(iter);
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btrfs_free_path(path);
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