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/ext2_fs.h>
   6 #include <linux/romfs_fs.h>
   7 #include <linux/initrd.h>
   8 #include <linux/sched.h>
   9 #include <linux/freezer.h>
  10
  11 #include "do_mounts.h"
  12
  13 unsigned long initrd_start, initrd_end;
  14 int initrd_below_start_ok;
  15 unsigned int real_root_dev;     /* do_proc_dointvec cannot handle kdev_t */
  16 static int __initdata old_fd, root_fd;
  17 static int __initdata mount_initrd = 1;
  18
  19 static int __init no_initrd(char *str)
  20 {
  21         mount_initrd = 0;
  22         return 1;
  23 }
  24
  25 __setup("noinitrd", no_initrd);
  26
  27 static int __init do_linuxrc(void *_shell)
  28 {
  29         static const char *argv[] = { "linuxrc", NULL, };
  30         extern const char *envp_init[];
  31         const char *shell = _shell;
  32
  33         sys_close(old_fd);sys_close(root_fd);
  34         sys_setsid();
  35         return kernel_execve(shell, argv, envp_init);
  36 }
  37
  38 static void __init handle_initrd(void)
  39 {
  40         int error;
  41         int pid;
  42
  43         real_root_dev = new_encode_dev(ROOT_DEV);
  44         create_dev("/dev/root.old", Root_RAM0);
  45         /* mount initrd on rootfs' /root */
  46         mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
  47         sys_mkdir("/old", 0700);
  48         root_fd = sys_open("/", 0, 0);
  49         old_fd = sys_open("/old", 0, 0);
  50         /* move initrd over / and chdir/chroot in initrd root */
  51         sys_chdir("/root");
  52         sys_mount(".", "/", NULL, MS_MOVE, NULL);
  53         sys_chroot(".");
  54
  55         /*
  56          * In case that a resume from disk is carried out by linuxrc or one of
  57          * its children, we need to tell the freezer not to wait for us.
  58          */
  59         current->flags |= PF_FREEZER_SKIP;
  60
  61         pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
  62         if (pid > 0)
  63                 while (pid != sys_wait4(-1, NULL, 0, NULL))
  64                         yield();
  65
  66         current->flags &= ~PF_FREEZER_SKIP;
  67
  68         /* move initrd to rootfs' /old */
  69         sys_fchdir(old_fd);
  70         sys_mount("/", ".", NULL, MS_MOVE, NULL);
  71         /* switch root and cwd back to / of rootfs */
  72         sys_fchdir(root_fd);
  73         sys_chroot(".");
  74         sys_close(old_fd);
  75         sys_close(root_fd);
  76
  77         if (new_decode_dev(real_root_dev) == Root_RAM0) {
  78                 sys_chdir("/old");
  79                 return;
  80         }
  81
  82         ROOT_DEV = new_decode_dev(real_root_dev);
  83         mount_root();
  84
  85         printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
  86         error = sys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
  87         if (!error)
  88                 printk("okay\n");
  89         else {
  90                 int fd = sys_open("/dev/root.old", O_RDWR, 0);
  91                 if (error == -ENOENT)
  92                         printk("/initrd does not exist. Ignored.\n");
  93                 else
  94                         printk("failed\n");
  95                 printk(KERN_NOTICE "Unmounting old root\n");
  96                 sys_umount("/old", MNT_DETACH);
  97                 printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
  98                 if (fd < 0) {
  99                         error = fd;
 100                 } else {
 101                         error = sys_ioctl(fd, BLKFLSBUF, 0);
 102                         sys_close(fd);
 103                 }
 104                 printk(!error ? "okay\n" : "failed\n");
 105         }
 106 }
 107
 108 int __init initrd_load(void)
 109 {
 110         if (mount_initrd) {
 111                 create_dev("/dev/ram", Root_RAM0);
 112                 /*
 113                  * Load the initrd data into /dev/ram0. Execute it as initrd
 114                  * unless /dev/ram0 is supposed to be our actual root device,
 115                  * in that case the ram disk is just set up here, and gets
 116                  * mounted in the normal path.
 117                  */
 118                 if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
 119                         sys_unlink("/initrd.image");
 120                         handle_initrd();
 121                         return 1;
 122                 }
 123         }
 124         sys_unlink("/initrd.image");
 125         return 0;
 126 }