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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 
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 }
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