btrfs: relocation: Cleanup while loop using rbtree_postorder_for_each_entry_safe

And add one line comment explaining what we're doing for each loop.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 3e6e3d9..0c1bc7d 100644 (file)
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -2991,7 +2991,7 @@ int relocate_tree_blocks(struct btrfs_trans_handle *trans,
        struct backref_node *node;
        struct btrfs_path *path;
        struct tree_block *block;
-       struct rb_node *rb_node;
+       struct tree_block *next;
        int ret;
        int err = 0;
 
@@ -3001,29 +3001,23 @@ int relocate_tree_blocks(struct btrfs_trans_handle *trans,
                goto out_free_blocks;
        }
 
-       rb_node = rb_first(blocks);
-       while (rb_node) {
-               block = rb_entry(rb_node, struct tree_block, rb_node);
+       /* Kick in readahead for tree blocks with missing keys */
+       rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {
                if (!block->key_ready)
                        readahead_tree_block(fs_info, block->bytenr);
-               rb_node = rb_next(rb_node);
        }
 
-       rb_node = rb_first(blocks);
-       while (rb_node) {
-               block = rb_entry(rb_node, struct tree_block, rb_node);
+       /* Get first keys */
+       rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {
                if (!block->key_ready) {
                        err = get_tree_block_key(fs_info, block);
                        if (err)
                                goto out_free_path;
                }
-               rb_node = rb_next(rb_node);
        }
 
-       rb_node = rb_first(blocks);
-       while (rb_node) {
-               block = rb_entry(rb_node, struct tree_block, rb_node);
-
+       /* Do tree relocation */
+       rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {
                node = build_backref_tree(rc, &block->key,
                                          block->level, block->bytenr);
                if (IS_ERR(node)) {
@@ -3034,11 +3028,10 @@ int relocate_tree_blocks(struct btrfs_trans_handle *trans,
                ret = relocate_tree_block(trans, rc, node, &block->key,
                                          path);
                if (ret < 0) {
-                       if (ret != -EAGAIN || rb_node == rb_first(blocks))
+                       if (ret != -EAGAIN || &block->rb_node == rb_first(blocks))
                                err = ret;
                        goto out;
                }
-               rb_node = rb_next(rb_node);
        }
 out:
        err = finish_pending_nodes(trans, rc, path, err);