From fd3e007f6c6a0f677e4ee8aca4b9bab8ad6cab9a Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 30 May 2019 17:48:35 -0400 Subject: [PATCH] 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 --- fs/namespace.c | 7 +------ include/linux/init.h | 3 +++ init/do_mounts.c | 15 ++------------- 3 files changed, 6 insertions(+), 19 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"); diff --git a/include/linux/init.h b/include/linux/init.h index 5255069f5a9f..cbe93521397e 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -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; diff --git a/init/do_mounts.c b/init/do_mounts.c index c170d8b309b1..e7f0b0f18cce 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -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; }