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Commit fd3e007f authored by Al Viro's avatar Al Viro
Browse files

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: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 14a253ce

fs/namespace.c

+1 −6
Original line number Diff line number Diff line
@@ -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");

include/linux/init.h

+3 −0
Original line number Diff line number Diff line
@@ -137,6 +137,8 @@ extern initcall_entry_t __con_initcall_start[], __con_initcall_end[]; 
/* Used for contructor calls. */

typedef void (*ctor_fn_t)(void);



struct file_system_type;



/* Defined in init/main.c */

extern int do_one_initcall(initcall_t fn);

extern char __initdata boot_command_line[];
@@ -147,6 +149,7 @@ extern unsigned int reset_devices; 
void setup_arch(char **);

void prepare_namespace(void);

int __init init_rootfs(void);

extern struct file_system_type rootfs_fs_type;



#if defined(CONFIG_STRICT_KERNEL_RWX) || defined(CONFIG_STRICT_MODULE_RWX)

extern bool rodata_enabled;

init/do_mounts.c

+2 −13
Original line number Diff line number Diff line
@@ -629,19 +629,15 @@ static bool is_tmpfs; 
static struct dentry *rootfs_mount(struct file_system_type *fs_type,

	int flags, const char *dev_name, void *data)

{

	static unsigned long once;

	void *fill = ramfs_fill_super;



	if (test_and_set_bit(0, &once))

		return ERR_PTR(-ENODEV);



	if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)

		fill = shmem_fill_super;



	return mount_nodev(fs_type, flags, data, fill);

}



static struct file_system_type rootfs_fs_type = {

struct file_system_type rootfs_fs_type = {

	.name		= "rootfs",

	.mount		= rootfs_mount,

	.kill_sb	= kill_litter_super,
@@ -649,19 +645,12 @@ static struct file_system_type rootfs_fs_type = { 


int __init init_rootfs(void)

{

	int err = register_filesystem(&rootfs_fs_type);



	if (err)

		return err;

	int err = 0;



	if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&

		(!root_fs_names || strstr(root_fs_names, "tmpfs"))) {

		err = shmem_init();

		is_tmpfs = true;

	}



	if (err)

		unregister_filesystem(&rootfs_fs_type);



	return err;

}