[PATCH v2 1/2] btrfs: relocation: Cleanup while() loop using rbtree_postorder_for_each_entry_safe()

[Qu Wenruo]

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

Signed-off-by: Qu Wenruo <w...@suse.com>
---
changelog:
v2:
  Use rbtree_postorder_for_each_entry_safe() to replace for() loop.
---
 fs/btrfs/relocation.c | 24 +++++++++---------------
 1 file changed, 9 insertions(+), 15 deletions(-)

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 8783a1776540..94aa148ccde6 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -2987,7 +2987,7 @@ 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;
 
@@ -2997,29 +2997,23 @@ 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)) {
@@ -3030,11 +3024,11 @@ 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);
-- 
2.19.0