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        /* 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
  51static 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
 119int __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 1;
 133                }
 134        }
 135        sys_unlink("/initrd.image");
 136        return 0;
 137}
 138
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