mirror of
https://github.com/torvalds/linux.git
synced 2024-11-08 21:21:47 +00:00
2bd3a997be
To avoid potential problems with an empty /dev open /dev/console from rootfs instead of waiting to mount our root filesystem and mounting it there. This effectively guarantees that there will be a device node, and it won't be on a filesystem that we will ever unmount, so there are no issues with leaving /dev/console open and pinning the filesystem. This is actually more effective than automatically mounting devtmpfs on /dev because it removes removes the occasionally problematic assumption that /dev/console exists from the boot code. With this patch I was able to throw busybox on my /boot partition (which has no /dev directory) and boot into userspace without problems. The only possible negative consequence I can think of is that someone out there deliberately used did not use a character device that is major 5 minor 2 for /dev/console. Does anyone know of a situation in which that could make sense? Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
126 lines
3.1 KiB
C
126 lines
3.1 KiB
C
#include <linux/unistd.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/minix_fs.h>
|
|
#include <linux/ext2_fs.h>
|
|
#include <linux/romfs_fs.h>
|
|
#include <linux/initrd.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/freezer.h>
|
|
|
|
#include "do_mounts.h"
|
|
|
|
unsigned long initrd_start, initrd_end;
|
|
int initrd_below_start_ok;
|
|
unsigned int real_root_dev; /* do_proc_dointvec cannot handle kdev_t */
|
|
static int __initdata old_fd, root_fd;
|
|
static int __initdata mount_initrd = 1;
|
|
|
|
static int __init no_initrd(char *str)
|
|
{
|
|
mount_initrd = 0;
|
|
return 1;
|
|
}
|
|
|
|
__setup("noinitrd", no_initrd);
|
|
|
|
static int __init do_linuxrc(void * shell)
|
|
{
|
|
static char *argv[] = { "linuxrc", NULL, };
|
|
extern char * envp_init[];
|
|
|
|
sys_close(old_fd);sys_close(root_fd);
|
|
sys_setsid();
|
|
return kernel_execve(shell, argv, envp_init);
|
|
}
|
|
|
|
static void __init handle_initrd(void)
|
|
{
|
|
int error;
|
|
int pid;
|
|
|
|
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);
|
|
sys_mkdir("/old", 0700);
|
|
root_fd = sys_open("/", 0, 0);
|
|
old_fd = sys_open("/old", 0, 0);
|
|
/* move initrd over / and chdir/chroot in initrd root */
|
|
sys_chdir("/root");
|
|
sys_mount(".", "/", NULL, MS_MOVE, NULL);
|
|
sys_chroot(".");
|
|
|
|
/*
|
|
* 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;
|
|
|
|
pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
|
|
if (pid > 0)
|
|
while (pid != sys_wait4(-1, NULL, 0, NULL))
|
|
yield();
|
|
|
|
current->flags &= ~PF_FREEZER_SKIP;
|
|
|
|
/* move initrd to rootfs' /old */
|
|
sys_fchdir(old_fd);
|
|
sys_mount("/", ".", NULL, MS_MOVE, NULL);
|
|
/* switch root and cwd back to / of rootfs */
|
|
sys_fchdir(root_fd);
|
|
sys_chroot(".");
|
|
sys_close(old_fd);
|
|
sys_close(root_fd);
|
|
|
|
if (new_decode_dev(real_root_dev) == Root_RAM0) {
|
|
sys_chdir("/old");
|
|
return;
|
|
}
|
|
|
|
ROOT_DEV = new_decode_dev(real_root_dev);
|
|
mount_root();
|
|
|
|
printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
|
|
error = sys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
|
|
if (!error)
|
|
printk("okay\n");
|
|
else {
|
|
int fd = sys_open("/dev/root.old", O_RDWR, 0);
|
|
if (error == -ENOENT)
|
|
printk("/initrd does not exist. Ignored.\n");
|
|
else
|
|
printk("failed\n");
|
|
printk(KERN_NOTICE "Unmounting old root\n");
|
|
sys_umount("/old", MNT_DETACH);
|
|
printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
|
|
if (fd < 0) {
|
|
error = fd;
|
|
} else {
|
|
error = sys_ioctl(fd, BLKFLSBUF, 0);
|
|
sys_close(fd);
|
|
}
|
|
printk(!error ? "okay\n" : "failed\n");
|
|
}
|
|
}
|
|
|
|
int __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) {
|
|
sys_unlink("/initrd.image");
|
|
handle_initrd();
|
|
return 1;
|
|
}
|
|
}
|
|
sys_unlink("/initrd.image");
|
|
return 0;
|
|
}
|