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, 17 insertions, 11 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 0acd85111cdf..f75e398d7b71 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -857,19 +857,22 @@ struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
 					   int slot)
 {
 	int level = btrfs_header_level(parent);
+	struct btrfs_tree_parent_check check = { 0 };
 	struct extent_buffer *eb;
-	struct btrfs_key first_key;
 
 	if (slot < 0 || slot >= btrfs_header_nritems(parent))
 		return ERR_PTR(-ENOENT);
 
 	BUG_ON(level == 0);
 
-	btrfs_node_key_to_cpu(parent, &first_key, slot);
+	check.level = level - 1;
+	check.transid = btrfs_node_ptr_generation(parent, slot);
+	check.owner_root = btrfs_header_owner(parent);
+	check.has_first_key = true;
+	btrfs_node_key_to_cpu(parent, &check.first_key, slot);
+
 	eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
-			     btrfs_header_owner(parent),
-			     btrfs_node_ptr_generation(parent, slot),
-			     level - 1, &first_key);
+			     &check);
 	if (IS_ERR(eb))
 		return eb;
 	if (!extent_buffer_uptodate(eb)) {
@@ -1428,10 +1431,10 @@ read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
 		      const struct btrfs_key *key)
 {
 	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_tree_parent_check check = { 0 };
 	u64 blocknr;
 	u64 gen;
 	struct extent_buffer *tmp;
-	struct btrfs_key first_key;
 	int ret;
 	int parent_level;
 	bool unlock_up;
@@ -1440,7 +1443,11 @@ read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
 	blocknr = btrfs_node_blockptr(*eb_ret, slot);
 	gen = btrfs_node_ptr_generation(*eb_ret, slot);
 	parent_level = btrfs_header_level(*eb_ret);
-	btrfs_node_key_to_cpu(*eb_ret, &first_key, slot);
+	btrfs_node_key_to_cpu(*eb_ret, &check.first_key, slot);
+	check.has_first_key = true;
+	check.level = parent_level - 1;
+	check.transid = gen;
+	check.owner_root = root->root_key.objectid;
 
 	/*
 	 * If we need to read an extent buffer from disk and we are holding locks
@@ -1462,7 +1469,7 @@ read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
 			 * parents (shared tree blocks).
 			 */
 			if (btrfs_verify_level_key(tmp,
-					parent_level - 1, &first_key, gen)) {
+					parent_level - 1, &check.first_key, gen)) {
 				free_extent_buffer(tmp);
 				return -EUCLEAN;
 			}
@@ -1479,7 +1486,7 @@ read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
 			btrfs_unlock_up_safe(p, level + 1);
 
 		/* now we're allowed to do a blocking uptodate check */
-		ret = btrfs_read_extent_buffer(tmp, gen, parent_level - 1, &first_key);
+		ret = btrfs_read_extent_buffer(tmp, &check);
 		if (ret) {
 			free_extent_buffer(tmp);
 			btrfs_release_path(p);
@@ -1509,8 +1516,7 @@ read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
 	if (p->reada != READA_NONE)
 		reada_for_search(fs_info, p, level, slot, key->objectid);
 
-	tmp = read_tree_block(fs_info, blocknr, root->root_key.objectid,
-			      gen, parent_level - 1, &first_key);
+	tmp = read_tree_block(fs_info, blocknr, &check);
 	if (IS_ERR(tmp)) {
 		btrfs_release_path(p);
 		return PTR_ERR(tmp);