init/do_mounts_initrd.c

   1 /*
   2  * Many of the syscalls used in this file expect some of the arguments
   3  * to be __user pointers not __kernel pointers.  To limit the sparse
   4  * noise, turn off sparse checking for this file.
   5  */
   6 #ifdef __CHECKER__
   7 #undef __CHECKER__
   8 #warning "Sparse checking disabled for this file"
   9 #endif
  10
  11 #include <linux/unistd.h>
  12 #include <linux/kernel.h>
  13 #include <linux/fs.h>
  14 #include <linux/minix_fs.h>
  15 #include <linux/romfs_fs.h>
  16 #include <linux/initrd.h>
  17 #include <linux/sched.h>
  18 #include <linux/freezer.h>
  19
  20 #include "do_mounts.h"
  21
  22 unsigned long initrd_start, initrd_end;
  23 int initrd_below_start_ok;
  24 unsigned int real_root_dev;     /* do_proc_dointvec cannot handle kdev_t */
  25 static int __initdata old_fd, root_fd;
  26 static int __initdata mount_initrd = 1;
  27
  28 static int __init no_initrd(char *str)
  29 {
  30         mount_initrd = 0;
  31         return 1;
  32 }
  33
  34 __setup("noinitrd", no_initrd);
  35
  36 static int __init do_linuxrc(void *_shell)
  37 {
  38         static const char *argv[] = { "linuxrc", NULL, };
  39         extern const char *envp_init[];
  40         const char *shell = _shell;
  41
  42         sys_close(old_fd);sys_close(root_fd);
  43         sys_setsid();
  44         return kernel_execve(shell, argv, envp_init);
  45 }
  46
  47 static void __init handle_initrd(void)
  48 {
  49         int error;
  50         int pid;
  51
  52         real_root_dev = new_encode_dev(ROOT_DEV);
  53         create_dev("/dev/root.old", Root_RAM0);
  54         /* mount initrd on rootfs' /root */
  55         mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
  56         sys_mkdir("/old", 0700);
  57         root_fd = sys_open("/", 0, 0);
  58         old_fd = sys_open("/old", 0, 0);
  59         /* move initrd over / and chdir/chroot in initrd root */
  60         sys_chdir("/root");
  61         sys_mount(".", "/", NULL, MS_MOVE, NULL);
  62         sys_chroot(".");
  63
  64         /*
  65          * In case that a resume from disk is carried out by linuxrc or one of
  66          * its children, we need to tell the freezer not to wait for us.
  67          */
  68         current->flags |= PF_FREEZER_SKIP;
  69
  70         pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
  71         if (pid > 0)
  72                 while (pid != sys_wait4(-1, NULL, 0, NULL))
  73                         yield();
  74
  75         current->flags &= ~PF_FREEZER_SKIP;
  76
  77         /* move initrd to rootfs' /old */
  78         sys_fchdir(old_fd);
  79         sys_mount("/", ".", NULL, MS_MOVE, NULL);
  80         /* switch root and cwd back to / of rootfs */
  81         sys_fchdir(root_fd);
  82         sys_chroot(".");
  83         sys_close(old_fd);
  84         sys_close(root_fd);
  85
  86         if (new_decode_dev(real_root_dev) == Root_RAM0) {
  87                 sys_chdir("/old");
  88                 return;
  89         }
  90
  91         ROOT_DEV = new_decode_dev(real_root_dev);
  92         mount_root();
  93
  94         printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
  95         error = sys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
  96         if (!error)
  97                 printk("okay\n");
  98         else {
  99                 int fd = sys_open("/dev/root.old", O_RDWR, 0);
 100                 if (error == -ENOENT)
 101                         printk("/initrd does not exist. Ignored.\n");
 102                 else
 103                         printk("failed\n");
 104                 printk(KERN_NOTICE "Unmounting old root\n");
 105                 sys_umount("/old", MNT_DETACH);
 106                 printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
 107                 if (fd < 0) {
 108                         error = fd;
 109                 } else {
 110                         error = sys_ioctl(fd, BLKFLSBUF, 0);
 111                         sys_close(fd);
 112                 }
 113                 printk(!error ? "okay\n" : "failed\n");
 114         }
 115 }
 116
 117 int __init initrd_load(void)
 118 {
 119         if (mount_initrd) {
 120                 create_dev("/dev/ram", Root_RAM0);
 121                 /*
 122                  * Load the initrd data into /dev/ram0. Execute it as initrd
 123                  * unless /dev/ram0 is supposed to be our actual root device,
 124                  * in that case the ram disk is just set up here, and gets
 125                  * mounted in the normal path.
 126                  */
 127                 if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
 128                         sys_unlink("/initrd.image");
 129                         handle_initrd();
 130                         return 1;
 131                 }
 132         }
 133         sys_unlink("/initrd.image");
 134         return 0;
 135 }