btrfs: concentrate all tree block parentness check parameters into one structure

There are several different tree block parentness check parameters used
across several helpers:

- level
  Mandatory

- transid
  Under most cases it's mandatory, but there are several backref cases
  which skips this check.

- owner_root
- first_key
  Utilized by most top-down tree search routine. Otherwise can be
  skipped.

Those four members are not always mandatory checks, and some of them are
the same u64, which means if some arguments got swapped compiler will
not catch it.

Furthermore if we're going to further expand the parentness check, we
need to modify quite some helpers just to add one more parameter.

This patch will concentrate all these members into a structure called
btrfs_tree_parent_check, and pass that structure for the following
helpers:

- btrfs_read_extent_buffer()
- read_tree_block()

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

1 files changed, 8 insertions, 4 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index b037107678c8..10cc757a602b 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5261,8 +5261,8 @@ static noinline int do_walk_down(struct btrfs_trans_handle *trans,
 	u64 bytenr;
 	u64 generation;
 	u64 parent;
+	struct btrfs_tree_parent_check check = { 0 };
 	struct btrfs_key key;
-	struct btrfs_key first_key;
 	struct btrfs_ref ref = { 0 };
 	struct extent_buffer *next;
 	int level = wc->level;
@@ -5284,7 +5284,12 @@ static noinline int do_walk_down(struct btrfs_trans_handle *trans,
 	}
 
 	bytenr = btrfs_node_blockptr(path->nodes[level], path->slots[level]);
-	btrfs_node_key_to_cpu(path->nodes[level], &first_key,
+
+	check.level = level - 1;
+	check.transid = generation;
+	check.owner_root = root->root_key.objectid;
+	check.has_first_key = true;
+	btrfs_node_key_to_cpu(path->nodes[level], &check.first_key,
 			      path->slots[level]);
 
 	next = find_extent_buffer(fs_info, bytenr);
@@ -5346,8 +5351,7 @@ static noinline int do_walk_down(struct btrfs_trans_handle *trans,
 	if (!next) {
 		if (reada && level == 1)
 			reada_walk_down(trans, root, wc, path);
-		next = read_tree_block(fs_info, bytenr, root->root_key.objectid,
-				       generation, level - 1, &first_key);
+		next = read_tree_block(fs_info, bytenr, &check);
 		if (IS_ERR(next)) {
 			return PTR_ERR(next);
 		} else if (!extent_buffer_uptodate(next)) {