init/do_mounts_initrd.c

   1 #include <linux/unistd.h>
   2 #include <linux/kernel.h>
   3 #include <linux/fs.h>
   4 #include <linux/minix_fs.h>
   5 #include <linux/romfs_fs.h>
   6 #include <linux/initrd.h>
   7 #include <linux/sched.h>
   8 #include <linux/freezer.h>
   9
  10 #include "do_mounts.h"
  11
  12 unsigned long initrd_start, initrd_end;
  13 int initrd_below_start_ok;
  14 unsigned int real_root_dev;     /* do_proc_dointvec cannot handle kdev_t */
  15 static int __initdata old_fd, root_fd;
  16 static int __initdata mount_initrd = 1;
  17
  18 static int __init no_initrd(char *str)
  19 {
  20         mount_initrd = 0;
  21         return 1;
  22 }
  23
  24 __setup("noinitrd", no_initrd);
  25
  26 static int __init do_linuxrc(void *_shell)
  27 {
  28         static const char *argv[] = { "linuxrc", NULL, };
  29         extern const char *envp_init[];
  30         const char *shell = _shell;
  31
  32         sys_close(old_fd);sys_close(root_fd);
  33         sys_setsid();
  34         return kernel_execve(shell, argv, envp_init);
  35 }
  36
  37 static void __init handle_initrd(void)
  38 {
  39         int error;
  40         int pid;
  41
  42         real_root_dev = new_encode_dev(ROOT_DEV);
  43         create_dev("/dev/root.old", Root_RAM0);
  44         /* mount initrd on rootfs' /root */
  45         mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
  46         sys_mkdir("/old", 0700);
  47         root_fd = sys_open("/", 0, 0);
  48         old_fd = sys_open("/old", 0, 0);
  49         /* move initrd over / and chdir/chroot in initrd root */
  50         sys_chdir("/root");
  51         sys_mount(".", "/", NULL, MS_MOVE, NULL);
  52         sys_chroot(".");
  53
  54         /*
  55          * In case that a resume from disk is carried out by linuxrc or one of
  56          * its children, we need to tell the freezer not to wait for us.
  57          */
  58         current->flags |= PF_FREEZER_SKIP;
  59
  60         pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
  61         if (pid > 0)
  62                 while (pid != sys_wait4(-1, NULL, 0, NULL))
  63                         yield();
  64
  65         current->flags &= ~PF_FREEZER_SKIP;
  66
  67         /* move initrd to rootfs' /old */
  68         sys_fchdir(old_fd);
  69         sys_mount("/", ".", NULL, MS_MOVE, NULL);
  70         /* switch root and cwd back to / of rootfs */
  71         sys_fchdir(root_fd);
  72         sys_chroot(".");
  73         sys_close(old_fd);
  74         sys_close(root_fd);
  75
  76         if (new_decode_dev(real_root_dev) == Root_RAM0) {
  77                 sys_chdir("/old");
  78                 return;
  79         }
  80
  81         ROOT_DEV = new_decode_dev(real_root_dev);
  82         mount_root();
  83
  84         printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
  85         error = sys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
  86         if (!error)
  87                 printk("okay\n");
  88         else {
  89                 int fd = sys_open("/dev/root.old", O_RDWR, 0);
  90                 if (error == -ENOENT)
  91                         printk("/initrd does not exist. Ignored.\n");
  92                 else
  93                         printk("failed\n");
  94                 printk(KERN_NOTICE "Unmounting old root\n");
  95                 sys_umount("/old", MNT_DETACH);
  96                 printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
  97                 if (fd < 0) {
  98                         error = fd;
  99                 } else {
 100                         error = sys_ioctl(fd, BLKFLSBUF, 0);
 101                         sys_close(fd);
 102                 }
 103                 printk(!error ? "okay\n" : "failed\n");
 104         }
 105 }
 106
 107 int __init initrd_load(void)
 108 {
 109         if (mount_initrd) {
 110                 create_dev("/dev/ram", Root_RAM0);
 111                 /*
 112                  * Load the initrd data into /dev/ram0. Execute it as initrd
 113                  * unless /dev/ram0 is supposed to be our actual root device,
 114                  * in that case the ram disk is just set up here, and gets
 115                  * mounted in the normal path.
 116                  */
 117                 if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
 118                         sys_unlink("/initrd.image");
 119                         handle_initrd();
 120                         return 1;
 121                 }
 122         }
 123         sys_unlink("/initrd.image");
 124         return 0;
 125 }