btrfs: tests, use BTRFS_FS_STATE_DUMMY_FS_INFO instead of dummy root

Now that we have a dummy fs_info associated with each test that
uses a root, we don't need the DUMMY_ROOT bit anymore.  This lets
us make choices without needing an actual root like in e.g.
btrfs_find_create_tree_block.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 8e838b1..ff2362d 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1146,7 +1146,7 @@
 struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
 						 u64 bytenr)
 {
-	if (btrfs_test_is_dummy_root(root))
+	if (btrfs_is_testing(root->fs_info))
 		return alloc_test_extent_buffer(root->fs_info, bytenr,
 				root->nodesize);
 	return alloc_extent_buffer(root->fs_info, bytenr);
@@ -1330,7 +1330,6 @@
 	/* We don't use the stripesize in selftest, set it as sectorsize */
 	__setup_root(nodesize, sectorsize, sectorsize, root, fs_info,
 			BTRFS_ROOT_TREE_OBJECTID);
-	set_bit(BTRFS_ROOT_DUMMY_ROOT, &root->state);
 	root->alloc_bytenr = 0;
 
 	return root;