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
20#include "do_mounts.h"
21
22unsigned long initrd_start, initrd_end;
23int initrd_below_start_ok;
24unsigned int real_root_dev; /* do_proc_dointvec cannot handle kdev_t */
25static int __initdata old_fd, root_fd;
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 do_linuxrc(void *_shell)
37{
38    static const char *argv[] = { "linuxrc", NULL, };
39    extern const char *envp_init[];
40    const char *shell = _shell;
41
42    sys_close(old_fd);sys_close(root_fd);
43    sys_setsid();
44    return kernel_execve(shell, argv, envp_init);
45}
46
47static void __init handle_initrd(void)
48{
49    int error;
50    int pid;
51
52    real_root_dev = new_encode_dev(ROOT_DEV);
53    create_dev("/dev/root.old", Root_RAM0);
54    /* mount initrd on rootfs' /root */
55    mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
56    sys_mkdir("/old", 0700);
57    root_fd = sys_open("/", 0, 0);
58    old_fd = sys_open("/old", 0, 0);
59    /* move initrd over / and chdir/chroot in initrd root */
60    sys_chdir("/root");
61    sys_mount(".", "/", NULL, MS_MOVE, NULL);
62    sys_chroot(".");
63
64    /*
65     * In case that a resume from disk is carried out by linuxrc or one of
66     * its children, we need to tell the freezer not to wait for us.
67     */
68    current->flags |= PF_FREEZER_SKIP;
69
70    pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
71    if (pid > 0)
72        while (pid != sys_wait4(-1, NULL, 0, NULL))
73            yield();
74
75    current->flags &= ~PF_FREEZER_SKIP;
76
77    /* move initrd to rootfs' /old */
78    sys_fchdir(old_fd);
79    sys_mount("/", ".", NULL, MS_MOVE, NULL);
80    /* switch root and cwd back to / of rootfs */
81    sys_fchdir(root_fd);
82    sys_chroot(".");
83    sys_close(old_fd);
84    sys_close(root_fd);
85
86    if (new_decode_dev(real_root_dev) == Root_RAM0) {
87        sys_chdir("/old");
88        return;
89    }
90
91    ROOT_DEV = new_decode_dev(real_root_dev);
92    mount_root();
93
94    printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
95    error = sys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
96    if (!error)
97        printk("okay\n");
98    else {
99        int fd = sys_open("/dev/root.old", O_RDWR, 0);
100        if (error == -ENOENT)
101            printk("/initrd does not exist. Ignored.\n");
102        else
103            printk("failed\n");
104        printk(KERN_NOTICE "Unmounting old root\n");
105        sys_umount("/old", MNT_DETACH);
106        printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
107        if (fd < 0) {
108            error = fd;
109        } else {
110            error = sys_ioctl(fd, BLKFLSBUF, 0);
111            sys_close(fd);
112        }
113        printk(!error ? "okay\n" : "failed\n");
114    }
115}
116
117int __init initrd_load(void)
118{
119    if (mount_initrd) {
120        create_dev("/dev/ram", Root_RAM0);
121        /*
122         * Load the initrd data into /dev/ram0. Execute it as initrd
123         * unless /dev/ram0 is supposed to be our actual root device,
124         * in that case the ram disk is just set up here, and gets
125         * mounted in the normal path.
126         */
127        if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
128            sys_unlink("/initrd.image");
129            handle_initrd();
130            return 1;
131        }
132    }
133    sys_unlink("/initrd.image");
134    return 0;
135}
136

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