root/init/do_mounts_initrd.c

DEFINITIONS

1. no_initrd
2. do_linuxrc
3. handle_initrd
4. initrd_load

#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_close(0);sys_close(1);sys_close(2);
        sys_setsid();
        (void) sys_open("/dev/console",O_RDWR,0);
        (void) sys_dup(0);
        (void) sys_dup(0);
        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;
}