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, 36 insertions, 27 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index e602e0b4c25d..2f944a7c70d5 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -259,13 +259,11 @@ int btrfs_verify_level_key(struct extent_buffer *eb, int level,
  * helper to read a given tree block, doing retries as required when
  * the checksums don't match and we have alternate mirrors to try.
  *
- * @parent_transid:	expected transid, skip check if 0
- * @level:		expected level, mandatory check
- * @first_key:		expected key of first slot, skip check if NULL
+ * @check:		expected tree parentness check, see the comments of the
+ *			structure for details.
  */
 int btrfs_read_extent_buffer(struct extent_buffer *eb,
-			     u64 parent_transid, int level,
-			     struct btrfs_key *first_key)
+			     struct btrfs_tree_parent_check *check)
 {
 	struct btrfs_fs_info *fs_info = eb->fs_info;
 	struct extent_io_tree *io_tree;
@@ -275,16 +273,19 @@ int btrfs_read_extent_buffer(struct extent_buffer *eb,
 	int mirror_num = 0;
 	int failed_mirror = 0;
 
+	ASSERT(check);
+
 	io_tree = &BTRFS_I(fs_info->btree_inode)->io_tree;
 	while (1) {
 		clear_bit(EXTENT_BUFFER_CORRUPT, &eb->bflags);
 		ret = read_extent_buffer_pages(eb, WAIT_COMPLETE, mirror_num);
 		if (!ret) {
-			if (verify_parent_transid(io_tree, eb,
-						   parent_transid, 0))
+			if (verify_parent_transid(io_tree, eb, check->transid, 0))
 				ret = -EIO;
-			else if (btrfs_verify_level_key(eb, level,
-						first_key, parent_transid))
+			else if (btrfs_verify_level_key(eb, check->level,
+						check->has_first_key ?
+						&check->first_key : NULL,
+						check->transid))
 				ret = -EUCLEAN;
 			else
 				break;
@@ -936,28 +937,28 @@ struct extent_buffer *btrfs_find_create_tree_block(
  * Read tree block at logical address @bytenr and do variant basic but critical
  * verification.
  *
- * @owner_root:		the objectid of the root owner for this block.
- * @parent_transid:	expected transid of this tree block, skip check if 0
- * @level:		expected level, mandatory check
- * @first_key:		expected key in slot 0, skip check if NULL
+ * @check:		expected tree parentness check, see comments of the
+ *			structure for details.
  */
 struct extent_buffer *read_tree_block(struct btrfs_fs_info *fs_info, u64 bytenr,
-				      u64 owner_root, u64 parent_transid,
-				      int level, struct btrfs_key *first_key)
+				      struct btrfs_tree_parent_check *check)
 {
 	struct extent_buffer *buf = NULL;
 	int ret;
 
-	buf = btrfs_find_create_tree_block(fs_info, bytenr, owner_root, level);
+	ASSERT(check);
+
+	buf = btrfs_find_create_tree_block(fs_info, bytenr, check->owner_root,
+					   check->level);
 	if (IS_ERR(buf))
 		return buf;
 
-	ret = btrfs_read_extent_buffer(buf, parent_transid, level, first_key);
+	ret = btrfs_read_extent_buffer(buf, check);
 	if (ret) {
 		free_extent_buffer_stale(buf);
 		return ERR_PTR(ret);
 	}
-	if (btrfs_check_eb_owner(buf, owner_root)) {
+	if (btrfs_check_eb_owner(buf, check->owner_root)) {
 		free_extent_buffer_stale(buf);
 		return ERR_PTR(-EUCLEAN);
 	}
@@ -1373,6 +1374,7 @@ static struct btrfs_root *read_tree_root_path(struct btrfs_root *tree_root,
 					      struct btrfs_key *key)
 {
 	struct btrfs_root *root;
+	struct btrfs_tree_parent_check check = { 0 };
 	struct btrfs_fs_info *fs_info = tree_root->fs_info;
 	u64 generation;
 	int ret;
@@ -1392,9 +1394,11 @@ static struct btrfs_root *read_tree_root_path(struct btrfs_root *tree_root,
 
 	generation = btrfs_root_generation(&root->root_item);
 	level = btrfs_root_level(&root->root_item);
-	root->node = read_tree_block(fs_info,
-				     btrfs_root_bytenr(&root->root_item),
-				     key->objectid, generation, level, NULL);
+	check.level = level;
+	check.transid = generation;
+	check.owner_root = key->objectid;
+	root->node = read_tree_block(fs_info, btrfs_root_bytenr(&root->root_item),
+				     &check);
 	if (IS_ERR(root->node)) {
 		ret = PTR_ERR(root->node);
 		root->node = NULL;
@@ -2367,6 +2371,7 @@ static int btrfs_replay_log(struct btrfs_fs_info *fs_info,
 			    struct btrfs_fs_devices *fs_devices)
 {
 	int ret;
+	struct btrfs_tree_parent_check check = { 0 };
 	struct btrfs_root *log_tree_root;
 	struct btrfs_super_block *disk_super = fs_info->super_copy;
 	u64 bytenr = btrfs_super_log_root(disk_super);
@@ -2382,10 +2387,10 @@ static int btrfs_replay_log(struct btrfs_fs_info *fs_info,
 	if (!log_tree_root)
 		return -ENOMEM;
 
-	log_tree_root->node = read_tree_block(fs_info, bytenr,
-					      BTRFS_TREE_LOG_OBJECTID,
-					      fs_info->generation + 1, level,
-					      NULL);
+	check.level = level;
+	check.transid = fs_info->generation + 1;
+	check.owner_root = BTRFS_TREE_LOG_OBJECTID;
+	log_tree_root->node = read_tree_block(fs_info, bytenr, &check);
 	if (IS_ERR(log_tree_root->node)) {
 		btrfs_warn(fs_info, "failed to read log tree");
 		ret = PTR_ERR(log_tree_root->node);
@@ -2863,10 +2868,14 @@ out:
 
 static int load_super_root(struct btrfs_root *root, u64 bytenr, u64 gen, int level)
 {
+	struct btrfs_tree_parent_check check = {
+		.level = level,
+		.transid = gen,
+		.owner_root = root->root_key.objectid
+	};
 	int ret = 0;
 
-	root->node = read_tree_block(root->fs_info, bytenr,
-				     root->root_key.objectid, gen, level, NULL);
+	root->node = read_tree_block(root->fs_info, bytenr, &check);
 	if (IS_ERR(root->node)) {
 		ret = PTR_ERR(root->node);
 		root->node = NULL;