Root/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
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    static char *argv[] = { "linuxrc", NULL, };
54    extern char *envp_init[];
55    int error;
56
57    real_root_dev = new_encode_dev(ROOT_DEV);
58    create_dev("/dev/root.old", Root_RAM0);
59    /* mount initrd on rootfs' /root */
60    mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
61    sys_mkdir("/old", 0700);
62    sys_chdir("/old");
63
64    /* try loading default modules from initrd */
65    load_default_modules();
66
67    /*
68     * In case that a resume from disk is carried out by linuxrc or one of
69     * its children, we need to tell the freezer not to wait for us.
70     */
71    current->flags |= PF_FREEZER_SKIP;
72
73    call_usermodehelper_fns("/linuxrc", argv, envp_init, UMH_WAIT_PROC,
74            init_linuxrc, NULL, NULL);
75
76    current->flags &= ~PF_FREEZER_SKIP;
77
78    /* move initrd to rootfs' /old */
79    sys_mount("..", ".", NULL, MS_MOVE, NULL);
80    /* switch root and cwd back to / of rootfs */
81    sys_chroot("..");
82
83    if (new_decode_dev(real_root_dev) == Root_RAM0) {
84        sys_chdir("/old");
85        return;
86    }
87
88    sys_chdir("/");
89    ROOT_DEV = new_decode_dev(real_root_dev);
90    mount_root();
91
92    printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
93    error = sys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
94    if (!error)
95        printk("okay\n");
96    else {
97        int fd = sys_open("/dev/root.old", O_RDWR, 0);
98        if (error == -ENOENT)
99            printk("/initrd does not exist. Ignored.\n");
100        else
101            printk("failed\n");
102        printk(KERN_NOTICE "Unmounting old root\n");
103        sys_umount("/old", MNT_DETACH);
104        printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
105        if (fd < 0) {
106            error = fd;
107        } else {
108            error = sys_ioctl(fd, BLKFLSBUF, 0);
109            sys_close(fd);
110        }
111        printk(!error ? "okay\n" : "failed\n");
112    }
113}
114
115int __init initrd_load(void)
116{
117    if (mount_initrd) {
118        create_dev("/dev/ram", Root_RAM0);
119        /*
120         * Load the initrd data into /dev/ram0. Execute it as initrd
121         * unless /dev/ram0 is supposed to be our actual root device,
122         * in that case the ram disk is just set up here, and gets
123         * mounted in the normal path.
124         */
125        if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
126            sys_unlink("/initrd.image");
127            handle_initrd();
128            return 1;
129        }
130    }
131    sys_unlink("/initrd.image");
132    return 0;
133}
134

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