don't bother with registering rootfs

init_mount_tree() can get to rootfs_fs_type directly and that simplifies
a lot of things.  We don't need to register it, we don't need to look
it up *and* we don't need to bother with preventing subsequent userland
mounts.  That's the way we should've done that from the very beginning.

There is a user-visible change, namely the disappearance of "rootfs"
from /proc/filesystems.  Note that it's been unmountable all along
and it didn't show up in /proc/mounts; however, it *is* a user-visible
change and theoretically some script might've been using its presence
in /proc/filesystems to tell 2.4.11+ from earlier kernels.

*IF* any complaints about behaviour change do show up, we could fake
it in /proc/filesystems.  I very much doubt we'll have to, though.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 1 insertions, 6 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 1141641dff96..2db2f4c36c50 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3686,13 +3686,8 @@ static void __init init_mount_tree(void)
 	struct mount *m;
 	struct mnt_namespace *ns;
 	struct path root;
-	struct file_system_type *type;
 
-	type = get_fs_type("rootfs");
-	if (!type)
-		panic("Can't find rootfs type");
-	mnt = vfs_kern_mount(type, 0, "rootfs", NULL);
-	put_filesystem(type);
+	mnt = vfs_kern_mount(&rootfs_fs_type, 0, "rootfs", NULL);
 	if (IS_ERR(mnt))
 		panic("Can't create rootfs");