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 #include <linux/kmod.h>
  20
  21 #include "do_mounts.h"
  22
  23 unsigned long initrd_start, initrd_end;
  24 int initrd_below_start_ok;
  25 unsigned int real_root_dev;     /* do_proc_dointvec cannot handle kdev_t */
  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_linuxrc(struct subprocess_info *info, struct cred *new)
  37 {
  38         sys_unshare(CLONE_FS | CLONE_FILES);
  39         /* stdin/stdout/stderr for /linuxrc */
  40         sys_open("/dev/console", O_RDWR, 0);
  41         sys_dup(0);
  42         sys_dup(0);
  43         /* move initrd over / and chdir/chroot in initrd root */
  44         sys_chdir("/root");
  45         sys_mount(".", "/", NULL, MS_MOVE, NULL);
  46         sys_chroot(".");
  47         sys_setsid();
  48         return 0;
  49 }
  50
  51 static void __init handle_initrd(void)
  52 {
  53         struct subprocess_info *info;
  54         static char *argv[] = { "linuxrc", NULL, };
  55         extern char *envp_init[];
  56         int error;
  57
  58         real_root_dev = new_encode_dev(ROOT_DEV);
  59         create_dev("/dev/root.old", Root_RAM0);
  60         /* mount initrd on rootfs' /root */
  61         mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
  62         sys_mkdir("/old", 0700);
  63         sys_chdir("/old");
  64
  65         /* try loading default modules from initrd */
  66         load_default_modules();
  67
  68         /*
  69          * In case that a resume from disk is carried out by linuxrc or one of
  70          * its children, we need to tell the freezer not to wait for us.
  71          */
  72         current->flags |= PF_FREEZER_SKIP;
  73
  74         info = call_usermodehelper_setup("/linuxrc", argv, envp_init,
  75                                          GFP_KERNEL, init_linuxrc, NULL, NULL);
  76         if (!info)
  77                 return;
  78         call_usermodehelper_exec(info, UMH_WAIT_PROC);
  79
  80         current->flags &= ~PF_FREEZER_SKIP;
  81
  82         /* move initrd to rootfs' /old */
  83         sys_mount("..", ".", NULL, MS_MOVE, NULL);
  84         /* switch root and cwd back to / of rootfs */
  85         sys_chroot("..");
  86
  87         if (new_decode_dev(real_root_dev) == Root_RAM0) {
  88                 sys_chdir("/old");
  89                 return;
  90         }
  91
  92         sys_chdir("/");
  93         ROOT_DEV = new_decode_dev(real_root_dev);
  94         mount_root();
  95
  96         printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
  97         error = sys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
  98         if (!error)
  99                 printk("okay\n");
 100         else {
 101                 int fd = sys_open("/dev/root.old", O_RDWR, 0);
 102                 if (error == -ENOENT)
 103                         printk("/initrd does not exist. Ignored.\n");
 104                 else
 105                         printk("failed\n");
 106                 printk(KERN_NOTICE "Unmounting old root\n");
 107                 sys_umount("/old", MNT_DETACH);
 108                 printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
 109                 if (fd < 0) {
 110                         error = fd;
 111                 } else {
 112                         error = sys_ioctl(fd, BLKFLSBUF, 0);
 113                         sys_close(fd);
 114                 }
 115                 printk(!error ? "okay\n" : "failed\n");
 116         }
 117 }
 118
 119 bool __init initrd_load(void)
 120 {
 121         if (mount_initrd) {
 122                 create_dev("/dev/ram", Root_RAM0);
 123                 /*
 124                  * Load the initrd data into /dev/ram0. Execute it as initrd
 125                  * unless /dev/ram0 is supposed to be our actual root device,
 126                  * in that case the ram disk is just set up here, and gets
 127                  * mounted in the normal path.
 128                  */
 129                 if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
 130                         sys_unlink("/initrd.image");
 131                         handle_initrd();
 132                         return true;
 133                 }
 134         }
 135         sys_unlink("/initrd.image");
 136         return false;
 137 }