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192.168.1.100 / T800 / 5e760d6e49c69fc1d6f033610ea11f0b461fda18 / . / src / kernel / linux / v4.19 / init / do_mounts_initrd.c
blob: d1a5d885ce13eb566667b5d32de782c6c4694944 [file] [log] [blame]
xjb04a4022021-11-25 15:01:52 +0800[diff] [blame]1// SPDX-License-Identifier: GPL-2.0
2#include <linux/unistd.h>
3#include <linux/kernel.h>
4#include <linux/fs.h>
5#include <linux/minix_fs.h>
6#include <linux/romfs_fs.h>
7#include <linux/initrd.h>
8#include <linux/sched.h>
9#include <linux/freezer.h>
10#include <linux/kmod.h>
11
12#include "do_mounts.h"
13
14unsigned long initrd_start, initrd_end;
15int initrd_below_start_ok;
16unsigned int real_root_dev; /* do_proc_dointvec cannot handle kdev_t */
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_linuxrc(struct subprocess_info *info, struct cred *new)
28{
29 ksys_unshare(CLONE_FS | CLONE_FILES);
30 /* stdin/stdout/stderr for /linuxrc */
31 ksys_open("/dev/console", O_RDWR, 0);
32 ksys_dup(0);
33 ksys_dup(0);
34 /* move initrd over / and chdir/chroot in initrd root */
35 ksys_chdir("/root");
36 ksys_mount(".", "/", NULL, MS_MOVE, NULL);
37 ksys_chroot(".");
38 ksys_setsid();
39 return 0;
40}
41
42static void __init handle_initrd(void)
43{
44 struct subprocess_info *info;
45 static char *argv[] = { "linuxrc", NULL, };
46 extern char *envp_init[];
47 int error;
48
49 real_root_dev = new_encode_dev(ROOT_DEV);
50 create_dev("/dev/root.old", Root_RAM0);
51 /* mount initrd on rootfs' /root */
52 mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);
53 ksys_mkdir("/old", 0700);
54 ksys_chdir("/old");
55
56 /* try loading default modules from initrd */
57 load_default_modules();
58
59 /*
60 * In case that a resume from disk is carried out by linuxrc or one of
61 * its children, we need to tell the freezer not to wait for us.
62 */
63 current->flags |= PF_FREEZER_SKIP;
64
65 info = call_usermodehelper_setup("/linuxrc", argv, envp_init,
66 GFP_KERNEL, init_linuxrc, NULL, NULL);
67 if (!info)
68 return;
69 call_usermodehelper_exec(info, UMH_WAIT_PROC);
70
71 current->flags &= ~PF_FREEZER_SKIP;
72
73 /* move initrd to rootfs' /old */
74 ksys_mount("..", ".", NULL, MS_MOVE, NULL);
75 /* switch root and cwd back to / of rootfs */
76 ksys_chroot("..");
77
78 if (new_decode_dev(real_root_dev) == Root_RAM0) {
79 ksys_chdir("/old");
80 return;
81 }
82
83 ksys_chdir("/");
84 ROOT_DEV = new_decode_dev(real_root_dev);
85 mount_root();
86
87 printk(KERN_NOTICE "Trying to move old root to /initrd ... ");
88 error = ksys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);
89 if (!error)
90 printk("okay\n");
91 else {
92 int fd = ksys_open("/dev/root.old", O_RDWR, 0);
93 if (error == -ENOENT)
94 printk("/initrd does not exist. Ignored.\n");
95 else
96 printk("failed\n");
97 printk(KERN_NOTICE "Unmounting old root\n");
98 ksys_umount("/old", MNT_DETACH);
99 printk(KERN_NOTICE "Trying to free ramdisk memory ... ");
100 if (fd < 0) {
101 error = fd;
102 } else {
103 error = ksys_ioctl(fd, BLKFLSBUF, 0);
104 ksys_close(fd);
105 }
106 printk(!error ? "okay\n" : "failed\n");
107 }
108}
109
110bool __init initrd_load(void)
111{
112 if (mount_initrd) {
113 create_dev("/dev/ram", Root_RAM0);
114 /*
115 * Load the initrd data into /dev/ram0. Execute it as initrd
116 * unless /dev/ram0 is supposed to be our actual root device,
117 * in that case the ram disk is just set up here, and gets
118 * mounted in the normal path.
119 */
120 if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {
121 ksys_unlink("/initrd.image");
122 handle_initrd();
123 return true;
124 }
125 }
126 ksys_unlink("/initrd.image");
127 return false;
128}