btrfs-progs: Add support for tree block operations on fs_info without roots

Since open_ctree_fs_info() now may return a fs_info even without any
roots, modify functions like read_tree_block() to operate with such
fs_info.

This provides the basis for btrfs-find-root to operate on chunk tree
with corrupted fs.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
[ coding style adjustments, unified declarations ]
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/volumes.c b/volumes.c
index 059c4f42..cc3e6b7f 100644
--- a/volumes.c
+++ b/volumes.c
@@ -1840,7 +1840,8 @@ int btrfs_read_sys_array(struct btrfs_root *root)
 	u32 cur_offset;
 	struct btrfs_key key;
 
-	sb = btrfs_find_create_tree_block(root, BTRFS_SUPER_INFO_OFFSET,
+	sb = btrfs_find_create_tree_block(root->fs_info,
+					  BTRFS_SUPER_INFO_OFFSET,
 					  BTRFS_SUPER_INFO_SIZE);
 	if (!sb)
 		return -ENOMEM;