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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/init/do_mounts_initrd.c
10817 views
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#include <linux/unistd.h>

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#include <linux/kernel.h>

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#include <linux/fs.h>

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#include <linux/minix_fs.h>

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#include <linux/ext2_fs.h>

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#include <linux/romfs_fs.h>

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#include <linux/initrd.h>

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#include <linux/sched.h>

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#include <linux/freezer.h>

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#include "do_mounts.h"

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unsigned long initrd_start, initrd_end;

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int initrd_below_start_ok;

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unsigned int real_root_dev;	/* do_proc_dointvec cannot handle kdev_t */

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static int __initdata old_fd, root_fd;

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static int __initdata mount_initrd = 1;

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static int __init no_initrd(char *str)

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{

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	mount_initrd = 0;

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	return 1;

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}

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__setup("noinitrd", no_initrd);

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static int __init do_linuxrc(void *_shell)

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{

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	static const char *argv[] = { "linuxrc", NULL, };

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	extern const char *envp_init[];

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	const char *shell = _shell;

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	sys_close(old_fd);sys_close(root_fd);

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	sys_setsid();

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	return kernel_execve(shell, argv, envp_init);

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}

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static void __init handle_initrd(void)

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{

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	int error;

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	int pid;

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	real_root_dev = new_encode_dev(ROOT_DEV);

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	create_dev("/dev/root.old", Root_RAM0);

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	/* mount initrd on rootfs' /root */

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	mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY);

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	sys_mkdir("/old", 0700);

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	root_fd = sys_open("/", 0, 0);

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	old_fd = sys_open("/old", 0, 0);

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	/* move initrd over / and chdir/chroot in initrd root */

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	sys_chdir("/root");

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	sys_mount(".", "/", NULL, MS_MOVE, NULL);

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	sys_chroot(".");

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	/*

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	 * In case that a resume from disk is carried out by linuxrc or one of

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	 * its children, we need to tell the freezer not to wait for us.

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	 */

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	current->flags |= PF_FREEZER_SKIP;

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	pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD);

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	if (pid > 0)

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		while (pid != sys_wait4(-1, NULL, 0, NULL))

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			yield();

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	current->flags &= ~PF_FREEZER_SKIP;

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	/* move initrd to rootfs' /old */

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	sys_fchdir(old_fd);

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	sys_mount("/", ".", NULL, MS_MOVE, NULL);

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	/* switch root and cwd back to / of rootfs */

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	sys_fchdir(root_fd);

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	sys_chroot(".");

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	sys_close(old_fd);

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	sys_close(root_fd);

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	if (new_decode_dev(real_root_dev) == Root_RAM0) {

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		sys_chdir("/old");

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		return;

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	}

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	ROOT_DEV = new_decode_dev(real_root_dev);

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	mount_root();

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	printk(KERN_NOTICE "Trying to move old root to /initrd ... ");

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	error = sys_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL);

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	if (!error)

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		printk("okay\n");

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	else {

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		int fd = sys_open("/dev/root.old", O_RDWR, 0);

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		if (error == -ENOENT)

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			printk("/initrd does not exist. Ignored.\n");

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		else

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			printk("failed\n");

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		printk(KERN_NOTICE "Unmounting old root\n");

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		sys_umount("/old", MNT_DETACH);

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		printk(KERN_NOTICE "Trying to free ramdisk memory ... ");

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		if (fd < 0) {

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			error = fd;

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		} else {

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			error = sys_ioctl(fd, BLKFLSBUF, 0);

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			sys_close(fd);

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		}

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		printk(!error ? "okay\n" : "failed\n");

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	}

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}

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int __init initrd_load(void)

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{

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	if (mount_initrd) {

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		create_dev("/dev/ram", Root_RAM0);

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		/*

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		 * Load the initrd data into /dev/ram0. Execute it as initrd

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		 * unless /dev/ram0 is supposed to be our actual root device,

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		 * in that case the ram disk is just set up here, and gets

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		 * mounted in the normal path.

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		 */

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		if (rd_load_image("/initrd.image") && ROOT_DEV != Root_RAM0) {

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			sys_unlink("/initrd.image");

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			handle_initrd();

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			return 1;

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		}

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	}

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	sys_unlink("/initrd.image");

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	return 0;

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}

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