linux/init/do_mounts_initrd.c
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   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
  23unsigned long initrd_start, initrd_end;
  24int initrd_below_start_ok;
  25unsigned int real_root_dev;     /* do_proc_dointvec cannot handle kdev_t */
  26static int __initdata mount_initrd = 1;
  27
  28static int __init no_initrd(char *str)
  29{
  30        mount_initrd = 0;
  31        return 1;
  32}
  33
  34__setup("noinitrd", no_initrd);
  35
  36static 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
  47static 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
 108int __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}
 127
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