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 const char *argv[] = { "linuxrc", NULL, };
30    extern const char *envp_init[];
31    const char *shell = _shell;
32
33    sys_close(old_fd);sys_close(root_fd);
34    sys_setsid();
35    return kernel_execve(shell, argv, envp_init);
36}
37
38static void __init handle_initrd(void)
39{
40    int error;
41    int pid;
42
43    real_root_dev = new_encode_dev(ROOT_DEV);
44    create_dev("/dev/root.old", Root_RAM0);
45    /* mount initrd on rootfs' /root */
46    mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
47    sys_mkdir("/old", 0700);
48    root_fd = sys_open("/", 0, 0);
49    old_fd = sys_open("/old", 0, 0);
50    /* move initrd over / and chdir/chroot in initrd root */
51    sys_chdir("/root");
52    sys_mount(".", "/", NULL, MS_MOVE, NULL);
53    sys_chroot(".");
54
55    /*
56     * In case that a resume from disk is carried out by linuxrc or one of
57     * its children, we need to tell the freezer not to wait for us.
58     */
59    current->flags |= PF_FREEZER_SKIP;
60
61    pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);
62    if (pid > 0)
63        while (pid != sys_wait4(-1, NULL, 0, NULL))
64            yield();
65
66    current->flags &= ~PF_FREEZER_SKIP;
67
68    /* move initrd to rootfs' /old */
69    sys_fchdir(old_fd);
70    sys_mount("/", ".", NULL, MS_MOVE, NULL);
71    /* switch root and cwd back to / of rootfs */
72    sys_fchdir(root_fd);
73    sys_chroot(".");
74    sys_close(old_fd);
75    sys_close(root_fd);
76
77    if (new_decode_dev(real_root_dev) == Root_RAM0) {
78        sys_chdir("/old");
79        return;
80    }
81
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
108int __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}
127

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