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         /* move initrd over / and chdir/chroot in initrd root */
  40         sys_chdir("/root");
  41         sys_mount(".", "/", NULL, MS_MOVE, NULL);
  42         sys_chroot(".");
  43         sys_setsid();
  44         return 0;
  45 }
  46
  47 static void __init handle_initrd(void)
  48 {
  49         static char *argv[] = { "linuxrc", NULL, };
  50         extern char *envp_init[];
  51         int error;
  52
  53         real_root_dev = new_encode_dev(ROOT_DEV);
  54         create_dev("/dev/root.old", Root_RAM0);
  55         /* mount initrd on rootfs' /root */
  56         mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
  57         sys_mkdir("/old", 0700);
  58         sys_chdir("/old");
  59
  60         /*
  61          * In case that a resume from disk is carried out by linuxrc or one of
  62          * its children, we need to tell the freezer not to wait for us.
  63          */
  64         current->flags |= PF_FREEZER_SKIP;
  65
  66         call_usermodehelper_fns("/linuxrc", argv, envp_init, UMH_WAIT_PROC,
  67                         init_linuxrc, NULL, NULL);
  68
  69         current->flags &= ~PF_FREEZER_SKIP;
  70
  71         /* move initrd to rootfs' /old */
  72         sys_mount("..", ".", NULL, MS_MOVE, NULL);
  73         /* switch root and cwd back to / of rootfs */
  74         sys_chroot("..");
  75
  76         if (new_decode_dev(real_root_dev) == Root_RAM0) {
  77                 sys_chdir("/old");
  78                 return;
  79         }
  80
  81         sys_chdir("/");
  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 }