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linux-next/init/do_mounts_initrd.c
tangmeng d772cc2c32 kernel/do_mount_initrd: move real_root_dev sysctls to its own file
kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.

To help with this maintenance let's start by moving sysctls to places
where they actually belong.  The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.

All filesystem syctls now get reviewed by fs folks. This commit
follows the commit of fs, move the real_root_dev sysctl to its own file,
kernel/do_mount_initrd.c.

Signed-off-by: tangmeng <tangmeng@uniontech.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2022-04-06 13:43:44 -07:00

163 lines
3.9 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <linux/unistd.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/minix_fs.h>
#include <linux/romfs_fs.h>
#include <linux/initrd.h>
#include <linux/sched.h>
#include <linux/freezer.h>
#include <linux/kmod.h>
#include <uapi/linux/mount.h>
#include "do_mounts.h"
unsigned long initrd_start, initrd_end;
int initrd_below_start_ok;
static unsigned int real_root_dev; /* do_proc_dointvec cannot handle kdev_t */
static int __initdata mount_initrd = 1;
phys_addr_t phys_initrd_start __initdata;
unsigned long phys_initrd_size __initdata;
#ifdef CONFIG_SYSCTL
static struct ctl_table kern_do_mounts_initrd_table[] = {
{
.procname = "real-root-dev",
.data = &real_root_dev,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{ }
};
static __init int kernel_do_mounts_initrd_sysctls_init(void)
{
register_sysctl_init("kernel", kern_do_mounts_initrd_table);
return 0;
}
late_initcall(kernel_do_mounts_initrd_sysctls_init);
#endif /* CONFIG_SYSCTL */
static int __init no_initrd(char *str)
{
mount_initrd = 0;
return 1;
}
__setup("noinitrd", no_initrd);
static int __init early_initrdmem(char *p)
{
phys_addr_t start;
unsigned long size;
char *endp;
start = memparse(p, &endp);
if (*endp == ',') {
size = memparse(endp + 1, NULL);
phys_initrd_start = start;
phys_initrd_size = size;
}
return 0;
}
early_param("initrdmem", early_initrdmem);
static int __init early_initrd(char *p)
{
return early_initrdmem(p);
}
early_param("initrd", early_initrd);
static int __init init_linuxrc(struct subprocess_info *info, struct cred *new)
{
ksys_unshare(CLONE_FS | CLONE_FILES);
console_on_rootfs();
/* move initrd over / and chdir/chroot in initrd root */
init_chdir("/root");
init_mount(".", "/", NULL, MS_MOVE, NULL);
init_chroot(".");
ksys_setsid();
return 0;
}
static void __init handle_initrd(void)
{
struct subprocess_info *info;
static char *argv[] = { "linuxrc", NULL, };
extern char *envp_init[];
int error;
pr_warn("using deprecated initrd support, will be removed in 2021.\n");
real_root_dev = new_encode_dev(ROOT_DEV);
create_dev("/dev/root.old", Root_RAM0);
/* mount initrd on rootfs' /root */
mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
init_mkdir("/old", 0700);
init_chdir("/old");
/*
* In case that a resume from disk is carried out by linuxrc or one of
* its children, we need to tell the freezer not to wait for us.
*/
current->flags |= PF_FREEZER_SKIP;
info = call_usermodehelper_setup("/linuxrc", argv, envp_init,
GFP_KERNEL, init_linuxrc, NULL, NULL);
if (!info)
return;
call_usermodehelper_exec(info, UMH_WAIT_PROC);
current->flags &= ~PF_FREEZER_SKIP;
/* move initrd to rootfs' /old */
init_mount("..", ".", NULL, MS_MOVE, NULL);
/* switch root and cwd back to / of rootfs */
init_chroot("..");
if (new_decode_dev(real_root_dev) == Root_RAM0) {
init_chdir("/old");
return;
}
init_chdir("/");
ROOT_DEV = new_decode_dev(real_root_dev);
mount_root();
printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
error = init_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
if (!error)
printk("okay\n");
else {
if (error == -ENOENT)
printk("/initrd does not exist. Ignored.\n");
else
printk("failed\n");
printk(KERN_NOTICE "Unmounting old root\n");
init_umount("/old", MNT_DETACH);
}
}
bool __init initrd_load(void)
{
if (mount_initrd) {
create_dev("/dev/ram", Root_RAM0);
/*
* Load the initrd data into /dev/ram0. Execute it as initrd
* unless /dev/ram0 is supposed to be our actual root device,
* in that case the ram disk is just set up here, and gets
* mounted in the normal path.
*/
if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
init_unlink("/initrd.image");
handle_initrd();
return true;
}
}
init_unlink("/initrd.image");
return false;
}