/*
   * Many of the syscalls used in this file expect some of the arguments
   * to be __user pointers not __kernel pointers.  To limit the sparse
   * noise, turn off sparse checking for this file.
   */
  #ifdef __CHECKER__
  #undef __CHECKER__
  #warning "Sparse checking disabled for this file"
  #endif

  #include <linux/module.h>
  #include <linux/sched.h>
  #include <linux/ctype.h>
  #include <linux/fd.h>
  #include <linux/tty.h>
  #include <linux/suspend.h>
  #include <linux/root_dev.h>
  #include <linux/security.h>
  #include <linux/delay.h>

  #include <linux/genhd.h>

  #include <linux/mount.h>

  #include <linux/device.h>

  #include <linux/init.h>

  #include <linux/fs.h>

  #include <linux/initrd.h>

  #include <linux/async.h>

  #include <linux/fs_struct.h>

  #include <linux/slab.h>

  #include <linux/ramfs.h>

  #include <linux/shmem_fs.h>

  
  #include <linux/nfs_fs.h>
  #include <linux/nfs_fs_sb.h>
  #include <linux/nfs_mount.h>
  
  #include "do_mounts.h"

  int __initdata rd_doload;	/* 1 = load RAM disk, 0 = don't load */

  int root_mountflags = MS_RDONLY | MS_SILENT;

  static char * __initdata root_device_name;

  static char __initdata saved_root_name[64];

  static int root_wait;

  dev_t ROOT_DEV;

  static int __init load_ramdisk(char *str)
  {
  	rd_doload = simple_strtol(str,NULL,0) & 3;
  	return 1;
  }
  __setup("load_ramdisk=", load_ramdisk);
  
  static int __init readonly(char *str)
  {
  	if (*str)
  		return 0;
  	root_mountflags |= MS_RDONLY;
  	return 1;
  }
  
  static int __init readwrite(char *str)
  {
  	if (*str)
  		return 0;
  	root_mountflags &= ~MS_RDONLY;
  	return 1;
  }
  
  __setup("ro", readonly);
  __setup("rw", readwrite);

  #ifdef CONFIG_BLOCK

  struct uuidcmp {
  	const char *uuid;
  	int len;
  };

  /**
   * match_dev_by_uuid - callback for finding a partition using its uuid
   * @dev:	device passed in by the caller

   * @data:	opaque pointer to the desired struct uuidcmp to match

   *
   * Returns 1 if the device matches, and 0 otherwise.
   */

  static int match_dev_by_uuid(struct device *dev, const void *data)

  {

  	const struct uuidcmp *cmp = data;

  	struct hd_struct *part = dev_to_part(dev);
  
  	if (!part->info)
  		goto no_match;

  	if (strncasecmp(cmp->uuid, part->info->uuid, cmp->len))
  		goto no_match;

  
  	return 1;
  no_match:
  	return 0;
  }
  
  
  /**
   * devt_from_partuuid - looks up the dev_t of a partition by its UUID

   * @uuid_str:	char array containing ascii UUID

   *
   * The function will return the first partition which contains a matching
   * UUID value in its partition_meta_info struct.  This does not search
   * by filesystem UUIDs.
   *

   * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be

   * extracted and used as an offset from the partition identified by the UUID.
   *

   * Returns the matching dev_t on success or 0 on failure.
   */

  static dev_t devt_from_partuuid(const char *uuid_str)

  {
  	dev_t res = 0;

  	struct uuidcmp cmp;

  	struct device *dev = NULL;

  	struct gendisk *disk;
  	struct hd_struct *part;
  	int offset = 0;

  	bool clear_root_wait = false;
  	char *slash;

  	cmp.uuid = uuid_str;

  	slash = strchr(uuid_str, '/');

  	/* Check for optional partition number offset attributes. */

  	if (slash) {

  		char c = 0;
  		/* Explicitly fail on poor PARTUUID syntax. */

  		if (sscanf(slash + 1,
  			   "PARTNROFF=%d%c", &offset, &c) != 1) {
  			clear_root_wait = true;

  			goto done;
  		}

  		cmp.len = slash - uuid_str;
  	} else {
  		cmp.len = strlen(uuid_str);
  	}
  
  	if (!cmp.len) {
  		clear_root_wait = true;
  		goto done;

  	}

  	dev = class_find_device(&block_class, NULL, &cmp,
  				&match_dev_by_uuid);

  	if (!dev)
  		goto done;
  
  	res = dev->devt;

  	/* Attempt to find the partition by offset. */
  	if (!offset)
  		goto no_offset;
  
  	res = 0;
  	disk = part_to_disk(dev_to_part(dev));
  	part = disk_get_part(disk, dev_to_part(dev)->partno + offset);
  	if (part) {
  		res = part_devt(part);
  		put_device(part_to_dev(part));
  	}
  
  no_offset:
  	put_device(dev);

  done:

  	if (clear_root_wait) {
  		pr_err("VFS: PARTUUID= is invalid.
  "
  		       "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]
  ");
  		if (root_wait)
  			pr_err("Disabling rootwait; root= is invalid.
  ");
  		root_wait = 0;
  	}

  	return res;
  }

  #endif

  /*
   *	Convert a name into device number.  We accept the following variants:
   *

   *	1) <hex_major><hex_minor> device number in hexadecimal represents itself
   *         no leading 0x, for example b302.

   *	2) /dev/nfs represents Root_NFS (0xff)
   *	3) /dev/<disk_name> represents the device number of disk
   *	4) /dev/<disk_name><decimal> represents the device number
   *         of partition - device number of disk plus the partition number
   *	5) /dev/<disk_name>p<decimal> - same as the above, that form is
   *	   used when disk name of partitioned disk ends on a digit.

   *	6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
   *	   unique id of a partition if the partition table provides it.

   *	   The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
   *	   partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
   *	   filled hex representation of the 32-bit "NT disk signature", and PP
   *	   is a zero-filled hex representation of the 1-based partition number.

   *	7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
   *	   a partition with a known unique id.

   *	8) <major>:<minor> major and minor number of the device separated by
   *	   a colon.

   *

   *	If name doesn't have fall into the categories above, we return (0,0).
   *	block_class is used to check if something is a disk name. If the disk
   *	name contains slashes, the device name has them replaced with
   *	bangs.

   */

  dev_t name_to_dev_t(const char *name)

  {
  	char s[32];
  	char *p;
  	dev_t res = 0;

  	int part;

  #ifdef CONFIG_BLOCK

  	if (strncmp(name, "PARTUUID=", 9) == 0) {
  		name += 9;

  		res = devt_from_partuuid(name);
  		if (!res)
  			goto fail;
  		goto done;
  	}

  #endif

  	if (strncmp(name, "/dev/", 5) != 0) {

  		unsigned maj, min, offset;

  		char dummy;

  		if ((sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2) ||
  		    (sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3)) {

  			res = MKDEV(maj, min);
  			if (maj != MAJOR(res) || min != MINOR(res))
  				goto fail;
  		} else {
  			res = new_decode_dev(simple_strtoul(name, &p, 16));
  			if (*p)
  				goto fail;
  		}
  		goto done;
  	}

  	name += 5;
  	res = Root_NFS;
  	if (strcmp(name, "nfs") == 0)
  		goto done;
  	res = Root_RAM0;
  	if (strcmp(name, "ram") == 0)
  		goto done;
  
  	if (strlen(name) > 31)
  		goto fail;
  	strcpy(s, name);
  	for (p = s; *p; p++)
  		if (*p == '/')
  			*p = '!';

  	res = blk_lookup_devt(s, 0);
  	if (res)
  		goto done;
  
  	/*

  	 * try non-existent, but valid partition, which may only exist

  	 * after revalidating the disk, like partitioned md devices
  	 */
  	while (p > s && isdigit(p[-1]))
  		p--;
  	if (p == s || !*p || *p == '0')
  		goto fail;
  
  	/* try disk name without <part number> */
  	part = simple_strtoul(p, NULL, 10);
  	*p = '\0';
  	res = blk_lookup_devt(s, part);
  	if (res)
  		goto done;
  
  	/* try disk name without p<part number> */
  	if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
  		goto fail;
  	p[-1] = '\0';
  	res = blk_lookup_devt(s, part);

  	if (res)
  		goto done;

  fail:
  	return 0;

  done:

  	return res;

  }

  EXPORT_SYMBOL_GPL(name_to_dev_t);

  
  static int __init root_dev_setup(char *line)
  {
  	strlcpy(saved_root_name, line, sizeof(saved_root_name));
  	return 1;
  }
  
  __setup("root=", root_dev_setup);

  static int __init rootwait_setup(char *str)
  {
  	if (*str)
  		return 0;
  	root_wait = 1;
  	return 1;
  }
  
  __setup("rootwait", rootwait_setup);

  static char * __initdata root_mount_data;
  static int __init root_data_setup(char *str)
  {
  	root_mount_data = str;
  	return 1;
  }
  
  static char * __initdata root_fs_names;
  static int __init fs_names_setup(char *str)
  {
  	root_fs_names = str;
  	return 1;
  }
  
  static unsigned int __initdata root_delay;
  static int __init root_delay_setup(char *str)
  {
  	root_delay = simple_strtoul(str, NULL, 0);
  	return 1;
  }
  
  __setup("rootflags=", root_data_setup);
  __setup("rootfstype=", fs_names_setup);
  __setup("rootdelay=", root_delay_setup);
  
  static void __init get_fs_names(char *page)
  {
  	char *s = page;
  
  	if (root_fs_names) {
  		strcpy(page, root_fs_names);
  		while (*s++) {
  			if (s[-1] == ',')
  				s[-1] = '\0';
  		}
  	} else {
  		int len = get_filesystem_list(page);
  		char *p, *next;
  
  		page[len] = '\0';
  		for (p = page-1; p; p = next) {
  			next = strchr(++p, '
  ');
  			if (*p++ != '\t')
  				continue;
  			while ((*s++ = *p++) != '
  ')
  				;
  			s[-1] = '\0';
  		}
  	}
  	*s = '\0';
  }
  
  static int __init do_mount_root(char *name, char *fs, int flags, void *data)
  {

  	struct super_block *s;

  	int err = sys_mount(name, "/root", fs, flags, data);
  	if (err)
  		return err;

  	sys_chdir("/root");

  	s = current->fs->pwd.dentry->d_sb;
  	ROOT_DEV = s->s_dev;

  	printk(KERN_INFO
  	       "VFS: Mounted root (%s filesystem)%s on device %u:%u.
  ",

  	       s->s_type->name,

  	       sb_rdonly(s) ? " readonly" : "",

  	       MAJOR(ROOT_DEV), MINOR(ROOT_DEV));

  	return 0;
  }
  
  void __init mount_block_root(char *name, int flags)
  {

  	struct page *page = alloc_page(GFP_KERNEL);

  	char *fs_names = page_address(page);

  	char *p;

  #ifdef CONFIG_BLOCK

  	char b[BDEVNAME_SIZE];

  #else
  	const char *b = name;
  #endif

  
  	get_fs_names(fs_names);
  retry:
  	for (p = fs_names; *p; p += strlen(p)+1) {
  		int err = do_mount_root(name, p, flags, root_mount_data);
  		switch (err) {
  			case 0:
  				goto out;
  			case -EACCES:

  			case -EINVAL:
  				continue;
  		}
  	        /*
  		 * Allow the user to distinguish between failed sys_open
  		 * and bad superblock on root device.

  		 * and give them a list of the available devices

  		 */

  #ifdef CONFIG_BLOCK

  		__bdevname(ROOT_DEV, b);

  #endif

  		printk("VFS: Cannot open root device \"%s\" or %s: error %d
  ",
  				root_device_name, b, err);

  		printk("Please append a correct \"root=\" boot option; here are the available partitions:
  ");

  		printk_all_partitions();

  #ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
  		printk("DEBUG_BLOCK_EXT_DEVT is enabled, you need to specify "
  		       "explicit textual name for \"root=\" boot option.
  ");
  #endif

  		panic("VFS: Unable to mount root fs on %s", b);
  	}

  	if (!(flags & SB_RDONLY)) {
  		flags |= SB_RDONLY;

  		goto retry;
  	}

  	printk("List of all partitions:
  ");
  	printk_all_partitions();

  	printk("No filesystem could mount root, tried: ");
  	for (p = fs_names; *p; p += strlen(p)+1)
  		printk(" %s", p);
  	printk("
  ");

  #ifdef CONFIG_BLOCK
  	__bdevname(ROOT_DEV, b);
  #endif
  	panic("VFS: Unable to mount root fs on %s", b);

  out:

  	put_page(page);

  }
   
  #ifdef CONFIG_ROOT_NFS

  
  #define NFSROOT_TIMEOUT_MIN	5
  #define NFSROOT_TIMEOUT_MAX	30
  #define NFSROOT_RETRY_MAX	5

  static int __init mount_nfs_root(void)
  {

  	char *root_dev, *root_data;

  	unsigned int timeout;
  	int try, err;

  	err = nfs_root_data(&root_dev, &root_data);
  	if (err != 0)

  		return 0;

  
  	/*
  	 * The server or network may not be ready, so try several
  	 * times.  Stop after a few tries in case the client wants
  	 * to fall back to other boot methods.
  	 */
  	timeout = NFSROOT_TIMEOUT_MIN;
  	for (try = 1; ; try++) {
  		err = do_mount_root(root_dev, "nfs",
  					root_mountflags, root_data);
  		if (err == 0)
  			return 1;
  		if (try > NFSROOT_RETRY_MAX)
  			break;
  
  		/* Wait, in case the server refused us immediately */
  		ssleep(timeout);
  		timeout <<= 1;
  		if (timeout > NFSROOT_TIMEOUT_MAX)
  			timeout = NFSROOT_TIMEOUT_MAX;
  	}
  	return 0;

  }
  #endif
  
  #if defined(CONFIG_BLK_DEV_RAM) || defined(CONFIG_BLK_DEV_FD)
  void __init change_floppy(char *fmt, ...)
  {
  	struct termios termios;
  	char buf[80];
  	char c;
  	int fd;
  	va_list args;
  	va_start(args, fmt);
  	vsprintf(buf, fmt, args);
  	va_end(args);
  	fd = sys_open("/dev/root", O_RDWR | O_NDELAY, 0);
  	if (fd >= 0) {
  		sys_ioctl(fd, FDEJECT, 0);
  		sys_close(fd);
  	}
  	printk(KERN_NOTICE "VFS: Insert %s and press ENTER
  ", buf);
  	fd = sys_open("/dev/console", O_RDWR, 0);
  	if (fd >= 0) {
  		sys_ioctl(fd, TCGETS, (long)&termios);
  		termios.c_lflag &= ~ICANON;
  		sys_ioctl(fd, TCSETSF, (long)&termios);
  		sys_read(fd, &c, 1);
  		termios.c_lflag |= ICANON;
  		sys_ioctl(fd, TCSETSF, (long)&termios);
  		sys_close(fd);
  	}
  }
  #endif
  
  void __init mount_root(void)
  {
  #ifdef CONFIG_ROOT_NFS

  	if (ROOT_DEV == Root_NFS) {

  		if (mount_nfs_root())
  			return;
  
  		printk(KERN_ERR "VFS: Unable to mount root fs via NFS, trying floppy.
  ");
  		ROOT_DEV = Root_FD0;
  	}
  #endif
  #ifdef CONFIG_BLK_DEV_FD
  	if (MAJOR(ROOT_DEV) == FLOPPY_MAJOR) {
  		/* rd_doload is 2 for a dual initrd/ramload setup */
  		if (rd_doload==2) {
  			if (rd_load_disk(1)) {
  				ROOT_DEV = Root_RAM1;
  				root_device_name = NULL;
  			}
  		} else
  			change_floppy("root floppy");
  	}
  #endif

  #ifdef CONFIG_BLOCK

  	{
  		int err = create_dev("/dev/root", ROOT_DEV);
  
  		if (err < 0)
  			pr_emerg("Failed to create /dev/root: %d
  ", err);
  		mount_block_root("/dev/root", root_mountflags);
  	}

  #endif

  }
  
  /*
   * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
   */
  void __init prepare_namespace(void)
  {
  	int is_floppy;

  	if (root_delay) {

  		printk(KERN_INFO "Waiting %d sec before mounting root device...
  ",

  		       root_delay);
  		ssleep(root_delay);
  	}

  	/*
  	 * wait for the known devices to complete their probing
  	 *
  	 * Note: this is a potential source of long boot delays.
  	 * For example, it is not atypical to wait 5 seconds here
  	 * for the touchpad of a laptop to initialize.
  	 */
  	wait_for_device_probe();

  	md_run_setup();
  
  	if (saved_root_name[0]) {
  		root_device_name = saved_root_name;

  		if (!strncmp(root_device_name, "mtd", 3) ||
  		    !strncmp(root_device_name, "ubi", 3)) {

  			mount_block_root(root_device_name, root_mountflags);
  			goto out;
  		}

  		ROOT_DEV = name_to_dev_t(root_device_name);
  		if (strncmp(root_device_name, "/dev/", 5) == 0)
  			root_device_name += 5;
  	}

  	if (initrd_load())
  		goto out;

  	/* wait for any asynchronous scanning to complete */
  	if ((ROOT_DEV == 0) && root_wait) {
  		printk(KERN_INFO "Waiting for root device %s...
  ",
  			saved_root_name);
  		while (driver_probe_done() != 0 ||
  			(ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)

  			msleep(5);

  		async_synchronize_full();

  	}
  
  	is_floppy = MAJOR(ROOT_DEV) == FLOPPY_MAJOR;

  	if (is_floppy && rd_doload && rd_load_disk(0))
  		ROOT_DEV = Root_RAM0;
  
  	mount_root();
  out:

  	devtmpfs_mount("dev");

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

  	sys_chroot(".");

  }

  static bool is_tmpfs;

  static struct dentry *rootfs_mount(struct file_system_type *fs_type,
  	int flags, const char *dev_name, void *data)
  {
  	static unsigned long once;

  	void *fill = ramfs_fill_super;

  
  	if (test_and_set_bit(0, &once))
  		return ERR_PTR(-ENODEV);

  	if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
  		fill = shmem_fill_super;
  
  	return mount_nodev(fs_type, flags, data, fill);

  }
  
  static struct file_system_type rootfs_fs_type = {
  	.name		= "rootfs",
  	.mount		= rootfs_mount,
  	.kill_sb	= kill_litter_super,
  };
  
  int __init init_rootfs(void)
  {
  	int err = register_filesystem(&rootfs_fs_type);
  
  	if (err)
  		return err;

  	if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
  		(!root_fs_names || strstr(root_fs_names, "tmpfs"))) {

  		err = shmem_init();

  		is_tmpfs = true;
  	} else {

  		err = init_ramfs_fs();

  	}

  	if (err)
  		unregister_filesystem(&rootfs_fs_type);
  
  	return err;
  }