Root/init/do_mounts_initrd.c

1#include <linux/unistd.h>
2#include <linux/kernel.h>
3#include <linux/fs.h>
4#include <linux/minix_fs.h>
5#include <linux/ext2_fs.h>
6#include <linux/romfs_fs.h>
7#include <linux/initrd.h>
8#include <linux/sched.h>
9#include <linux/freezer.h>
10
11#include "do_mounts.h"
12
13unsigned long initrd_start, initrd_end;
14int initrd_below_start_ok;
15unsigned int real_root_dev; /* do_proc_dointvec cannot handle kdev_t */
16static int __initdata old_fd, root_fd;
17static int __initdata mount_initrd = 1;
18
19static int __init no_initrd(char *str)
20{
21    mount_initrd = 0;
22    return 1;
23}
24
25__setup("noinitrd", no_initrd);
26
27static int __init do_linuxrc(void * shell)
28{
29    static char *argv[] = { "linuxrc", NULL, };
30    extern char * envp_init[];
31
32    sys_close(old_fd);sys_close(root_fd);
33    sys_setsid();
34    return kernel_execve(shell, argv, envp_init);
35}
36
37static void __init handle_initrd(void)
38{
39    int error;
40    int pid;
41
42    real_root_dev = new_encode_dev(ROOT_DEV);
43    create_dev("/dev/root.old", Root_RAM0);
44    /* mount initrd on rootfs' /root */
45    mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
46    sys_mkdir("/old", 0700);
47    root_fd = sys_open("/", 0, 0);
48    old_fd = sys_open("/old", 0, 0);
49    /* move initrd over / and chdir/chroot in initrd root */
50    sys_chdir("/root");
51    sys_mount(".", "/", NULL, MS_MOVE, NULL);
52    sys_chroot(".");
53
54    /*
55     * In case that a resume from disk is carried out by linuxrc or one of
56     * its children, we need to tell the freezer not to wait for us.
57     */
58    current->flags |= PF_FREEZER_SKIP;
59
60    pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
61    if (pid > 0)
62        while (pid != sys_wait4(-1, NULL, 0, NULL))
63            yield();
64
65    current->flags &= ~PF_FREEZER_SKIP;
66
67    /* move initrd to rootfs' /old */
68    sys_fchdir(old_fd);
69    sys_mount("/", ".", NULL, MS_MOVE, NULL);
70    /* switch root and cwd back to / of rootfs */
71    sys_fchdir(root_fd);
72    sys_chroot(".");
73    sys_close(old_fd);
74    sys_close(root_fd);
75
76    if (new_decode_dev(real_root_dev) == Root_RAM0) {
77        sys_chdir("/old");
78        return;
79    }
80
81    ROOT_DEV = new_decode_dev(real_root_dev);
82    mount_root();
83
84    printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
85    error = sys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
86    if (!error)
87        printk("okay\n");
88    else {
89        int fd = sys_open("/dev/root.old", O_RDWR, 0);
90        if (error == -ENOENT)
91            printk("/initrd does not exist. Ignored.\n");
92        else
93            printk("failed\n");
94        printk(KERN_NOTICE "Unmounting old root\n");
95        sys_umount("/old", MNT_DETACH);
96        printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
97        if (fd < 0) {
98            error = fd;
99        } else {
100            error = sys_ioctl(fd, BLKFLSBUF, 0);
101            sys_close(fd);
102        }
103        printk(!error ? "okay\n" : "failed\n");
104    }
105}
106
107int __init initrd_load(void)
108{
109    if (mount_initrd) {
110        create_dev("/dev/ram", Root_RAM0);
111        /*
112         * Load the initrd data into /dev/ram0. Execute it as initrd
113         * unless /dev/ram0 is supposed to be our actual root device,
114         * in that case the ram disk is just set up here, and gets
115         * mounted in the normal path.
116         */
117        if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
118            sys_unlink("/initrd.image");
119            handle_initrd();
120            return 1;
121        }
122    }
123    sys_unlink("/initrd.image");
124    return 0;
125}
126

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