btrfs: sink blocksize parameter to btrfs_find_create_tree_block

Finally it's clear that the requested blocksize is always equal to
nodesize, with one exception, the superblock.

Superblock has fixed size regardless of the metadata block size, but
uses the same helpers to initialize sys array/chunk tree and to work
with the chunk items. So it pretends to be an extent_buffer for a
moment, btrfs_read_sys_array is full of special cases, we're adding one
more.
Signed-off-by: David Sterba <dsterba@suse.cz>

fs/btrfs/disk-io.c

@@ -1078,7 +1078,7 @@ void readahead_tree_block(struct btrfs_root *root, u64 bytenr)
 	struct extent_buffer *buf = NULL;
 	struct inode *btree_inode = root->fs_info->btree_inode;
 
-	buf = btrfs_find_create_tree_block(root, bytenr, root->nodesize);
+	buf = btrfs_find_create_tree_block(root, bytenr);
 	if (!buf)
 		return;
 	read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree,
@@ -1094,7 +1094,7 @@ int reada_tree_block_flagged(struct btrfs_root *root, u64 bytenr,
 	struct extent_io_tree *io_tree = &BTRFS_I(btree_inode)->io_tree;
 	int ret;
 
-	buf = btrfs_find_create_tree_block(root, bytenr, root->nodesize);
+	buf = btrfs_find_create_tree_block(root, bytenr);
 	if (!buf)
 		return 0;
 
@@ -1125,12 +1125,12 @@ struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root,
 }
 
 struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
-						 u64 bytenr, u32 blocksize)
+						 u64 bytenr)
 {
 	if (btrfs_test_is_dummy_root(root))
 		return alloc_test_extent_buffer(root->fs_info, bytenr,
-						blocksize);
-	return alloc_extent_buffer(root->fs_info, bytenr, blocksize);
+						root->nodesize);
+	return alloc_extent_buffer(root->fs_info, bytenr, root->nodesize);
 }
 
 
@@ -1152,7 +1152,7 @@ struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
 	struct extent_buffer *buf = NULL;
 	int ret;
 
-	buf = btrfs_find_create_tree_block(root, bytenr, root->nodesize);
+	buf = btrfs_find_create_tree_block(root, bytenr);
 	if (!buf)
 		return NULL;
 

fs/btrfs/disk-io.h

@@ -50,7 +50,7 @@ void readahead_tree_block(struct btrfs_root *root, u64 bytenr);
 int reada_tree_block_flagged(struct btrfs_root *root, u64 bytenr,
 			 int mirror_num, struct extent_buffer **eb);
 struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
-						   u64 bytenr, u32 blocksize);
+						   u64 bytenr);
 void clean_tree_block(struct btrfs_trans_handle *trans,
 		      struct btrfs_root *root, struct extent_buffer *buf);
 int open_ctree(struct super_block *sb,

fs/btrfs/extent-tree.c

@@ -7219,7 +7219,7 @@ btrfs_init_new_buffer(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 {
 	struct extent_buffer *buf;
 
-	buf = btrfs_find_create_tree_block(root, bytenr, root->nodesize);
+	buf = btrfs_find_create_tree_block(root, bytenr);
 	if (!buf)
 		return ERR_PTR(-ENOMEM);
 	btrfs_set_header_generation(buf, trans->transid);
@@ -7825,7 +7825,7 @@ static noinline int do_walk_down(struct btrfs_trans_handle *trans,
 
 	next = btrfs_find_tree_block(root, bytenr);
 	if (!next) {
-		next = btrfs_find_create_tree_block(root, bytenr, blocksize);
+		next = btrfs_find_create_tree_block(root, bytenr);
 		if (!next)
 			return -ENOMEM;
 		btrfs_set_buffer_lockdep_class(root->root_key.objectid, next,

fs/btrfs/tree-log.c

@@ -2164,7 +2164,7 @@ static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans,
 		parent = path->nodes[*level];
 		root_owner = btrfs_header_owner(parent);
 
-		next = btrfs_find_create_tree_block(root, bytenr, blocksize);
+		next = btrfs_find_create_tree_block(root, bytenr);
 		if (!next)
 			return -ENOMEM;
 

fs/btrfs/volumes.c

@@ -6247,8 +6247,13 @@ int btrfs_read_sys_array(struct btrfs_root *root)
 	u32 cur;
 	struct btrfs_key key;
 
-	sb = btrfs_find_create_tree_block(root, BTRFS_SUPER_INFO_OFFSET,
-					  BTRFS_SUPER_INFO_SIZE);
+	ASSERT(BTRFS_SUPER_INFO_SIZE <= root->nodesize);
+	/*
+	 * This will create extent buffer of nodesize, superblock size is
+	 * fixed to BTRFS_SUPER_INFO_SIZE. If nodesize > sb size, this will
+	 * overallocate but we can keep it as-is, only the first page is used.
+	 */
+	sb = btrfs_find_create_tree_block(root, BTRFS_SUPER_INFO_OFFSET);
 	if (!sb)
 		return -ENOMEM;
 	btrfs_set_buffer_uptodate(sb);