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  1/*
  2 * Many of the syscalls used in this file expect some of the arguments
  3 * to be __user pointers not __kernel pointers.  To limit the sparse
  4 * noise, turn off sparse checking for this file.
  5 */
  6#ifdef __CHECKER__
  7#undef __CHECKER__
  8#warning "Sparse checking disabled for this file"
  9#endif
 10
 11#include <linux/module.h>
 12#include <linux/sched.h>
 13#include <linux/ctype.h>
 14#include <linux/fd.h>
 15#include <linux/tty.h>
 16#include <linux/suspend.h>
 17#include <linux/root_dev.h>
 18#include <linux/security.h>
 19#include <linux/delay.h>
 20#include <linux/genhd.h>
 21#include <linux/mount.h>
 22#include <linux/device.h>
 23#include <linux/init.h>
 24#include <linux/fs.h>
 25#include <linux/initrd.h>
 26#include <linux/async.h>
 27#include <linux/fs_struct.h>
 28#include <linux/slab.h>
 29#include <linux/ramfs.h>
 30#include <linux/shmem_fs.h>
 31
 32#include <linux/nfs_fs.h>
 33#include <linux/nfs_fs_sb.h>
 34#include <linux/nfs_mount.h>
 35
 36#include "do_mounts.h"
 37
 38int __initdata rd_doload;	/* 1 = load RAM disk, 0 = don't load */
 39
 40int root_mountflags = MS_RDONLY | MS_SILENT;
 41static char * __initdata root_device_name;
 42static char __initdata saved_root_name[64];
 43static int root_wait;
 44
 45dev_t ROOT_DEV;
 46
 47static int __init load_ramdisk(char *str)
 48{
 49	rd_doload = simple_strtol(str,NULL,0) & 3;
 50	return 1;
 51}
 52__setup("load_ramdisk=", load_ramdisk);
 53
 54static int __init readonly(char *str)
 55{
 56	if (*str)
 57		return 0;
 58	root_mountflags |= MS_RDONLY;
 59	return 1;
 60}
 61
 62static int __init readwrite(char *str)
 63{
 64	if (*str)
 65		return 0;
 66	root_mountflags &= ~MS_RDONLY;
 67	return 1;
 68}
 69
 70__setup("ro", readonly);
 71__setup("rw", readwrite);
 72
 73#ifdef CONFIG_BLOCK
 74struct uuidcmp {
 75	const char *uuid;
 76	int len;
 77};
 78
 79/**
 80 * match_dev_by_uuid - callback for finding a partition using its uuid
 81 * @dev:	device passed in by the caller
 82 * @data:	opaque pointer to the desired struct uuidcmp to match
 83 *
 84 * Returns 1 if the device matches, and 0 otherwise.
 85 */
 86static int match_dev_by_uuid(struct device *dev, const void *data)
 87{
 88	const struct uuidcmp *cmp = data;
 89	struct hd_struct *part = dev_to_part(dev);
 90
 91	if (!part->info)
 92		goto no_match;
 93
 94	if (strncasecmp(cmp->uuid, part->info->uuid, cmp->len))
 95		goto no_match;
 96
 97	return 1;
 98no_match:
 99	return 0;
100}
101
102
103/**
104 * devt_from_partuuid - looks up the dev_t of a partition by its UUID
105 * @uuid_str:	char array containing ascii UUID
106 *
107 * The function will return the first partition which contains a matching
108 * UUID value in its partition_meta_info struct.  This does not search
109 * by filesystem UUIDs.
110 *
111 * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be
112 * extracted and used as an offset from the partition identified by the UUID.
113 *
114 * Returns the matching dev_t on success or 0 on failure.
115 */
116static dev_t devt_from_partuuid(const char *uuid_str)
117{
118	dev_t res = 0;
119	struct uuidcmp cmp;
120	struct device *dev = NULL;
121	struct gendisk *disk;
122	struct hd_struct *part;
123	int offset = 0;
124	bool clear_root_wait = false;
125	char *slash;
126
127	cmp.uuid = uuid_str;
128
129	slash = strchr(uuid_str, '/');
130	/* Check for optional partition number offset attributes. */
131	if (slash) {
132		char c = 0;
133		/* Explicitly fail on poor PARTUUID syntax. */
134		if (sscanf(slash + 1,
135			   "PARTNROFF=%d%c", &offset, &c) != 1) {
136			clear_root_wait = true;
137			goto done;
138		}
139		cmp.len = slash - uuid_str;
140	} else {
141		cmp.len = strlen(uuid_str);
142	}
143
144	if (!cmp.len) {
145		clear_root_wait = true;
146		goto done;
147	}
148
149	dev = class_find_device(&block_class, NULL, &cmp,
150				&match_dev_by_uuid);
151	if (!dev)
152		goto done;
153
154	res = dev->devt;
155
156	/* Attempt to find the partition by offset. */
157	if (!offset)
158		goto no_offset;
159
160	res = 0;
161	disk = part_to_disk(dev_to_part(dev));
162	part = disk_get_part(disk, dev_to_part(dev)->partno + offset);
163	if (part) {
164		res = part_devt(part);
165		put_device(part_to_dev(part));
166	}
167
168no_offset:
169	put_device(dev);
170done:
171	if (clear_root_wait) {
172		pr_err("VFS: PARTUUID= is invalid.\n"
173		       "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
174		if (root_wait)
175			pr_err("Disabling rootwait; root= is invalid.\n");
176		root_wait = 0;
177	}
178	return res;
179}
180#endif
181
182/*
183 *	Convert a name into device number.  We accept the following variants:
184 *
185 *	1) <hex_major><hex_minor> device number in hexadecimal represents itself
186 *         no leading 0x, for example b302.
187 *	2) /dev/nfs represents Root_NFS (0xff)
188 *	3) /dev/<disk_name> represents the device number of disk
189 *	4) /dev/<disk_name><decimal> represents the device number
190 *         of partition - device number of disk plus the partition number
191 *	5) /dev/<disk_name>p<decimal> - same as the above, that form is
192 *	   used when disk name of partitioned disk ends on a digit.
193 *	6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
194 *	   unique id of a partition if the partition table provides it.
195 *	   The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
196 *	   partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
197 *	   filled hex representation of the 32-bit "NT disk signature", and PP
198 *	   is a zero-filled hex representation of the 1-based partition number.
199 *	7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
200 *	   a partition with a known unique id.
201 *	8) <major>:<minor> major and minor number of the device separated by
202 *	   a colon.
203 *
204 *	If name doesn't have fall into the categories above, we return (0,0).
205 *	block_class is used to check if something is a disk name. If the disk
206 *	name contains slashes, the device name has them replaced with
207 *	bangs.
208 */
209
210dev_t name_to_dev_t(const char *name)
211{
212	char s[32];
213	char *p;
214	dev_t res = 0;
215	int part;
216
217#ifdef CONFIG_BLOCK
218	if (strncmp(name, "PARTUUID=", 9) == 0) {
219		name += 9;
220		res = devt_from_partuuid(name);
221		if (!res)
222			goto fail;
223		goto done;
224	}
225#endif
226
227	if (strncmp(name, "/dev/", 5) != 0) {
228		unsigned maj, min, offset;
229		char dummy;
230
231		if ((sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2) ||
232		    (sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3)) {
233			res = MKDEV(maj, min);
234			if (maj != MAJOR(res) || min != MINOR(res))
235				goto fail;
236		} else {
237			res = new_decode_dev(simple_strtoul(name, &p, 16));
238			if (*p)
239				goto fail;
240		}
241		goto done;
242	}
243
244	name += 5;
245	res = Root_NFS;
246	if (strcmp(name, "nfs") == 0)
247		goto done;
248	res = Root_RAM0;
249	if (strcmp(name, "ram") == 0)
250		goto done;
251
252	if (strlen(name) > 31)
253		goto fail;
254	strcpy(s, name);
255	for (p = s; *p; p++)
256		if (*p == '/')
257			*p = '!';
258	res = blk_lookup_devt(s, 0);
259	if (res)
260		goto done;
261
262	/*
263	 * try non-existent, but valid partition, which may only exist
264	 * after revalidating the disk, like partitioned md devices
265	 */
266	while (p > s && isdigit(p[-1]))
267		p--;
268	if (p == s || !*p || *p == '0')
269		goto fail;
270
271	/* try disk name without <part number> */
272	part = simple_strtoul(p, NULL, 10);
273	*p = '\0';
274	res = blk_lookup_devt(s, part);
275	if (res)
276		goto done;
277
278	/* try disk name without p<part number> */
279	if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
280		goto fail;
281	p[-1] = '\0';
282	res = blk_lookup_devt(s, part);
283	if (res)
284		goto done;
285
286fail:
287	return 0;
288done:
289	return res;
290}
291EXPORT_SYMBOL_GPL(name_to_dev_t);
292
293static int __init root_dev_setup(char *line)
294{
295	strlcpy(saved_root_name, line, sizeof(saved_root_name));
296	return 1;
297}
298
299__setup("root=", root_dev_setup);
300
301static int __init rootwait_setup(char *str)
302{
303	if (*str)
304		return 0;
305	root_wait = 1;
306	return 1;
307}
308
309__setup("rootwait", rootwait_setup);
310
311static char * __initdata root_mount_data;
312static int __init root_data_setup(char *str)
313{
314	root_mount_data = str;
315	return 1;
316}
317
318static char * __initdata root_fs_names;
319static int __init fs_names_setup(char *str)
320{
321	root_fs_names = str;
322	return 1;
323}
324
325static unsigned int __initdata root_delay;
326static int __init root_delay_setup(char *str)
327{
328	root_delay = simple_strtoul(str, NULL, 0);
329	return 1;
330}
331
332__setup("rootflags=", root_data_setup);
333__setup("rootfstype=", fs_names_setup);
334__setup("rootdelay=", root_delay_setup);
335
336static void __init get_fs_names(char *page)
337{
338	char *s = page;
339
340	if (root_fs_names) {
341		strcpy(page, root_fs_names);
342		while (*s++) {
343			if (s[-1] == ',')
344				s[-1] = '\0';
345		}
346	} else {
347		int len = get_filesystem_list(page);
348		char *p, *next;
349
350		page[len] = '\0';
351		for (p = page-1; p; p = next) {
352			next = strchr(++p, '\n');
353			if (*p++ != '\t')
354				continue;
355			while ((*s++ = *p++) != '\n')
356				;
357			s[-1] = '\0';
358		}
359	}
360	*s = '\0';
361}
362
363static int __init do_mount_root(char *name, char *fs, int flags, void *data)
364{
365	struct super_block *s;
366	int err = ksys_mount(name, "/root", fs, flags, data);
367	if (err)
368		return err;
369
370	ksys_chdir("/root");
371	s = current->fs->pwd.dentry->d_sb;
372	ROOT_DEV = s->s_dev;
373	printk(KERN_INFO
374	       "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
375	       s->s_type->name,
376	       sb_rdonly(s) ? " readonly" : "",
377	       MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
378	return 0;
379}
380
381void __init mount_block_root(char *name, int flags)
382{
383	struct page *page = alloc_page(GFP_KERNEL);
384	char *fs_names = page_address(page);
385	char *p;
386#ifdef CONFIG_BLOCK
387	char b[BDEVNAME_SIZE];
388#else
389	const char *b = name;
390#endif
391
392	get_fs_names(fs_names);
393retry:
394	for (p = fs_names; *p; p += strlen(p)+1) {
395		int err = do_mount_root(name, p, flags, root_mount_data);
396		switch (err) {
397			case 0:
398				goto out;
399			case -EACCES:
400			case -EINVAL:
401				continue;
402		}
403	        /*
404		 * Allow the user to distinguish between failed sys_open
405		 * and bad superblock on root device.
406		 * and give them a list of the available devices
407		 */
408#ifdef CONFIG_BLOCK
409		__bdevname(ROOT_DEV, b);
410#endif
411		printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
412				root_device_name, b, err);
413		printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
414
415		printk_all_partitions();
416#ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
417		printk("DEBUG_BLOCK_EXT_DEVT is enabled, you need to specify "
418		       "explicit textual name for \"root=\" boot option.\n");
419#endif
420		panic("VFS: Unable to mount root fs on %s", b);
421	}
422	if (!(flags & SB_RDONLY)) {
423		flags |= SB_RDONLY;
424		goto retry;
425	}
426
427	printk("List of all partitions:\n");
428	printk_all_partitions();
429	printk("No filesystem could mount root, tried: ");
430	for (p = fs_names; *p; p += strlen(p)+1)
431		printk(" %s", p);
432	printk("\n");
433#ifdef CONFIG_BLOCK
434	__bdevname(ROOT_DEV, b);
435#endif
436	panic("VFS: Unable to mount root fs on %s", b);
437out:
438	put_page(page);
439}
440 
441#ifdef CONFIG_ROOT_NFS
442
443#define NFSROOT_TIMEOUT_MIN	5
444#define NFSROOT_TIMEOUT_MAX	30
445#define NFSROOT_RETRY_MAX	5
446
447static int __init mount_nfs_root(void)
448{
449	char *root_dev, *root_data;
450	unsigned int timeout;
451	int try, err;
452
453	err = nfs_root_data(&root_dev, &root_data);
454	if (err != 0)
455		return 0;
456
457	/*
458	 * The server or network may not be ready, so try several
459	 * times.  Stop after a few tries in case the client wants
460	 * to fall back to other boot methods.
461	 */
462	timeout = NFSROOT_TIMEOUT_MIN;
463	for (try = 1; ; try++) {
464		err = do_mount_root(root_dev, "nfs",
465					root_mountflags, root_data);
466		if (err == 0)
467			return 1;
468		if (try > NFSROOT_RETRY_MAX)
469			break;
470
471		/* Wait, in case the server refused us immediately */
472		ssleep(timeout);
473		timeout <<= 1;
474		if (timeout > NFSROOT_TIMEOUT_MAX)
475			timeout = NFSROOT_TIMEOUT_MAX;
476	}
477	return 0;
478}
479#endif
480
481#if defined(CONFIG_BLK_DEV_RAM) || defined(CONFIG_BLK_DEV_FD)
482void __init change_floppy(char *fmt, ...)
483{
484	struct termios termios;
485	char buf[80];
486	char c;
487	int fd;
488	va_list args;
489	va_start(args, fmt);
490	vsprintf(buf, fmt, args);
491	va_end(args);
492	fd = ksys_open("/dev/root", O_RDWR | O_NDELAY, 0);
493	if (fd >= 0) {
494		ksys_ioctl(fd, FDEJECT, 0);
495		ksys_close(fd);
496	}
497	printk(KERN_NOTICE "VFS: Insert %s and press ENTER\n", buf);
498	fd = ksys_open("/dev/console", O_RDWR, 0);
499	if (fd >= 0) {
500		ksys_ioctl(fd, TCGETS, (long)&termios);
501		termios.c_lflag &= ~ICANON;
502		ksys_ioctl(fd, TCSETSF, (long)&termios);
503		ksys_read(fd, &c, 1);
504		termios.c_lflag |= ICANON;
505		ksys_ioctl(fd, TCSETSF, (long)&termios);
506		ksys_close(fd);
507	}
508}
509#endif
510
511void __init mount_root(void)
512{
513#ifdef CONFIG_ROOT_NFS
514	if (ROOT_DEV == Root_NFS) {
515		if (mount_nfs_root())
516			return;
517
518		printk(KERN_ERR "VFS: Unable to mount root fs via NFS, trying floppy.\n");
519		ROOT_DEV = Root_FD0;
520	}
521#endif
522#ifdef CONFIG_BLK_DEV_FD
523	if (MAJOR(ROOT_DEV) == FLOPPY_MAJOR) {
524		/* rd_doload is 2 for a dual initrd/ramload setup */
525		if (rd_doload==2) {
526			if (rd_load_disk(1)) {
527				ROOT_DEV = Root_RAM1;
528				root_device_name = NULL;
529			}
530		} else
531			change_floppy("root floppy");
532	}
533#endif
534#ifdef CONFIG_BLOCK
535	{
536		int err = create_dev("/dev/root", ROOT_DEV);
537
538		if (err < 0)
539			pr_emerg("Failed to create /dev/root: %d\n", err);
540		mount_block_root("/dev/root", root_mountflags);
541	}
542#endif
543}
544
545/*
546 * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
547 */
548void __init prepare_namespace(void)
549{
550	int is_floppy;
551
552	if (root_delay) {
553		printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
554		       root_delay);
555		ssleep(root_delay);
556	}
557
558	/*
559	 * wait for the known devices to complete their probing
560	 *
561	 * Note: this is a potential source of long boot delays.
562	 * For example, it is not atypical to wait 5 seconds here
563	 * for the touchpad of a laptop to initialize.
564	 */
565	wait_for_device_probe();
566
567	md_run_setup();
568
569	if (saved_root_name[0]) {
570		root_device_name = saved_root_name;
571		if (!strncmp(root_device_name, "mtd", 3) ||
572		    !strncmp(root_device_name, "ubi", 3)) {
573			mount_block_root(root_device_name, root_mountflags);
574			goto out;
575		}
576		ROOT_DEV = name_to_dev_t(root_device_name);
577		if (strncmp(root_device_name, "/dev/", 5) == 0)
578			root_device_name += 5;
579	}
580
581	if (initrd_load())
582		goto out;
583
584	/* wait for any asynchronous scanning to complete */
585	if ((ROOT_DEV == 0) && root_wait) {
586		printk(KERN_INFO "Waiting for root device %s...\n",
587			saved_root_name);
588		while (driver_probe_done() != 0 ||
589			(ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
590			msleep(5);
591		async_synchronize_full();
592	}
593
594	is_floppy = MAJOR(ROOT_DEV) == FLOPPY_MAJOR;
595
596	if (is_floppy && rd_doload && rd_load_disk(0))
597		ROOT_DEV = Root_RAM0;
598
599	mount_root();
600out:
601	devtmpfs_mount("dev");
602	ksys_mount(".", "/", NULL, MS_MOVE, NULL);
603	ksys_chroot(".");
604}
605
606static bool is_tmpfs;
607static struct dentry *rootfs_mount(struct file_system_type *fs_type,
608	int flags, const char *dev_name, void *data)
609{
610	static unsigned long once;
611	void *fill = ramfs_fill_super;
612
613	if (test_and_set_bit(0, &once))
614		return ERR_PTR(-ENODEV);
615
616	if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
617		fill = shmem_fill_super;
618
619	return mount_nodev(fs_type, flags, data, fill);
620}
621
622static struct file_system_type rootfs_fs_type = {
623	.name		= "rootfs",
624	.mount		= rootfs_mount,
625	.kill_sb	= kill_litter_super,
626};
627
628int __init init_rootfs(void)
629{
630	int err = register_filesystem(&rootfs_fs_type);
631
632	if (err)
633		return err;
634
635	if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
636		(!root_fs_names || strstr(root_fs_names, "tmpfs"))) {
637		err = shmem_init();
638		is_tmpfs = true;
639	} else {
640		err = init_ramfs_fs();
641	}
642
643	if (err)
644		unregister_filesystem(&rootfs_fs_type);
645
646	return err;
647}
  1// SPDX-License-Identifier: GPL-2.0-only
  2#include <linux/module.h>
  3#include <linux/sched.h>
  4#include <linux/ctype.h>
  5#include <linux/fd.h>
  6#include <linux/tty.h>
  7#include <linux/suspend.h>
  8#include <linux/root_dev.h>
  9#include <linux/security.h>
 10#include <linux/delay.h>
 11#include <linux/genhd.h>
 12#include <linux/mount.h>
 13#include <linux/device.h>
 14#include <linux/init.h>
 15#include <linux/fs.h>
 16#include <linux/initrd.h>
 17#include <linux/async.h>
 18#include <linux/fs_struct.h>
 19#include <linux/slab.h>
 20#include <linux/ramfs.h>
 21#include <linux/shmem_fs.h>
 22
 23#include <linux/nfs_fs.h>
 24#include <linux/nfs_fs_sb.h>
 25#include <linux/nfs_mount.h>
 26#include <linux/raid/detect.h>
 27#include <uapi/linux/mount.h>
 28
 29#include "do_mounts.h"
 30
 31int root_mountflags = MS_RDONLY | MS_SILENT;
 32static char * __initdata root_device_name;
 33static char __initdata saved_root_name[64];
 34static int root_wait;
 35
 36dev_t ROOT_DEV;
 37
 38static int __init load_ramdisk(char *str)
 39{
 40	pr_warn("ignoring the deprecated load_ramdisk= option\n");
 41	return 1;
 42}
 43__setup("load_ramdisk=", load_ramdisk);
 44
 45static int __init readonly(char *str)
 46{
 47	if (*str)
 48		return 0;
 49	root_mountflags |= MS_RDONLY;
 50	return 1;
 51}
 52
 53static int __init readwrite(char *str)
 54{
 55	if (*str)
 56		return 0;
 57	root_mountflags &= ~MS_RDONLY;
 58	return 1;
 59}
 60
 61__setup("ro", readonly);
 62__setup("rw", readwrite);
 63
 64#ifdef CONFIG_BLOCK
 65struct uuidcmp {
 66	const char *uuid;
 67	int len;
 68};
 69
 70/**
 71 * match_dev_by_uuid - callback for finding a partition using its uuid
 72 * @dev:	device passed in by the caller
 73 * @data:	opaque pointer to the desired struct uuidcmp to match
 74 *
 75 * Returns 1 if the device matches, and 0 otherwise.
 76 */
 77static int match_dev_by_uuid(struct device *dev, const void *data)
 78{
 79	const struct uuidcmp *cmp = data;
 80	struct hd_struct *part = dev_to_part(dev);
 81
 82	if (!part->info)
 83		goto no_match;
 84
 85	if (strncasecmp(cmp->uuid, part->info->uuid, cmp->len))
 86		goto no_match;
 87
 88	return 1;
 89no_match:
 90	return 0;
 91}
 92
 93
 94/**
 95 * devt_from_partuuid - looks up the dev_t of a partition by its UUID
 96 * @uuid_str:	char array containing ascii UUID
 97 *
 98 * The function will return the first partition which contains a matching
 99 * UUID value in its partition_meta_info struct.  This does not search
100 * by filesystem UUIDs.
101 *
102 * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be
103 * extracted and used as an offset from the partition identified by the UUID.
104 *
105 * Returns the matching dev_t on success or 0 on failure.
106 */
107static dev_t devt_from_partuuid(const char *uuid_str)
108{
109	dev_t res = 0;
110	struct uuidcmp cmp;
111	struct device *dev = NULL;
112	struct gendisk *disk;
113	struct hd_struct *part;
114	int offset = 0;
115	bool clear_root_wait = false;
116	char *slash;
117
118	cmp.uuid = uuid_str;
119
120	slash = strchr(uuid_str, '/');
121	/* Check for optional partition number offset attributes. */
122	if (slash) {
123		char c = 0;
124		/* Explicitly fail on poor PARTUUID syntax. */
125		if (sscanf(slash + 1,
126			   "PARTNROFF=%d%c", &offset, &c) != 1) {
127			clear_root_wait = true;
128			goto done;
129		}
130		cmp.len = slash - uuid_str;
131	} else {
132		cmp.len = strlen(uuid_str);
133	}
134
135	if (!cmp.len) {
136		clear_root_wait = true;
137		goto done;
138	}
139
140	dev = class_find_device(&block_class, NULL, &cmp,
141				&match_dev_by_uuid);
142	if (!dev)
143		goto done;
144
145	res = dev->devt;
146
147	/* Attempt to find the partition by offset. */
148	if (!offset)
149		goto no_offset;
150
151	res = 0;
152	disk = part_to_disk(dev_to_part(dev));
153	part = disk_get_part(disk, dev_to_part(dev)->partno + offset);
154	if (part) {
155		res = part_devt(part);
156		put_device(part_to_dev(part));
157	}
158
159no_offset:
160	put_device(dev);
161done:
162	if (clear_root_wait) {
163		pr_err("VFS: PARTUUID= is invalid.\n"
164		       "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
165		if (root_wait)
166			pr_err("Disabling rootwait; root= is invalid.\n");
167		root_wait = 0;
168	}
169	return res;
170}
171
172/**
173 * match_dev_by_label - callback for finding a partition using its label
174 * @dev:	device passed in by the caller
175 * @data:	opaque pointer to the label to match
176 *
177 * Returns 1 if the device matches, and 0 otherwise.
178 */
179static int match_dev_by_label(struct device *dev, const void *data)
180{
181	const char *label = data;
182	struct hd_struct *part = dev_to_part(dev);
183
184	if (part->info && !strcmp(label, part->info->volname))
185		return 1;
186
187	return 0;
188}
189#endif
190
191/*
192 *	Convert a name into device number.  We accept the following variants:
193 *
194 *	1) <hex_major><hex_minor> device number in hexadecimal represents itself
195 *         no leading 0x, for example b302.
196 *	2) /dev/nfs represents Root_NFS (0xff)
197 *	3) /dev/<disk_name> represents the device number of disk
198 *	4) /dev/<disk_name><decimal> represents the device number
199 *         of partition - device number of disk plus the partition number
200 *	5) /dev/<disk_name>p<decimal> - same as the above, that form is
201 *	   used when disk name of partitioned disk ends on a digit.
202 *	6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
203 *	   unique id of a partition if the partition table provides it.
204 *	   The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
205 *	   partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
206 *	   filled hex representation of the 32-bit "NT disk signature", and PP
207 *	   is a zero-filled hex representation of the 1-based partition number.
208 *	7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
209 *	   a partition with a known unique id.
210 *	8) <major>:<minor> major and minor number of the device separated by
211 *	   a colon.
212 *	9) PARTLABEL=<name> with name being the GPT partition label.
213 *	   MSDOS partitions do not support labels!
214 *	10) /dev/cifs represents Root_CIFS (0xfe)
215 *
216 *	If name doesn't have fall into the categories above, we return (0,0).
217 *	block_class is used to check if something is a disk name. If the disk
218 *	name contains slashes, the device name has them replaced with
219 *	bangs.
220 */
221
222dev_t name_to_dev_t(const char *name)
223{
224	char s[32];
225	char *p;
226	dev_t res = 0;
227	int part;
228
229#ifdef CONFIG_BLOCK
230	if (strncmp(name, "PARTUUID=", 9) == 0) {
231		name += 9;
232		res = devt_from_partuuid(name);
233		if (!res)
234			goto fail;
235		goto done;
236	} else if (strncmp(name, "PARTLABEL=", 10) == 0) {
237		struct device *dev;
238
239		dev = class_find_device(&block_class, NULL, name + 10,
240					&match_dev_by_label);
241		if (!dev)
242			goto fail;
243
244		res = dev->devt;
245		put_device(dev);
246		goto done;
247	}
248#endif
249
250	if (strncmp(name, "/dev/", 5) != 0) {
251		unsigned maj, min, offset;
252		char dummy;
253
254		if ((sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2) ||
255		    (sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3)) {
256			res = MKDEV(maj, min);
257			if (maj != MAJOR(res) || min != MINOR(res))
258				goto fail;
259		} else {
260			res = new_decode_dev(simple_strtoul(name, &p, 16));
261			if (*p)
262				goto fail;
263		}
264		goto done;
265	}
266
267	name += 5;
268	res = Root_NFS;
269	if (strcmp(name, "nfs") == 0)
270		goto done;
271	res = Root_CIFS;
272	if (strcmp(name, "cifs") == 0)
273		goto done;
274	res = Root_RAM0;
275	if (strcmp(name, "ram") == 0)
276		goto done;
277
278	if (strlen(name) > 31)
279		goto fail;
280	strcpy(s, name);
281	for (p = s; *p; p++)
282		if (*p == '/')
283			*p = '!';
284	res = blk_lookup_devt(s, 0);
285	if (res)
286		goto done;
287
288	/*
289	 * try non-existent, but valid partition, which may only exist
290	 * after revalidating the disk, like partitioned md devices
291	 */
292	while (p > s && isdigit(p[-1]))
293		p--;
294	if (p == s || !*p || *p == '0')
295		goto fail;
296
297	/* try disk name without <part number> */
298	part = simple_strtoul(p, NULL, 10);
299	*p = '\0';
300	res = blk_lookup_devt(s, part);
301	if (res)
302		goto done;
303
304	/* try disk name without p<part number> */
305	if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
306		goto fail;
307	p[-1] = '\0';
308	res = blk_lookup_devt(s, part);
309	if (res)
310		goto done;
311
312fail:
313	return 0;
314done:
315	return res;
316}
317EXPORT_SYMBOL_GPL(name_to_dev_t);
318
319static int __init root_dev_setup(char *line)
320{
321	strlcpy(saved_root_name, line, sizeof(saved_root_name));
322	return 1;
323}
324
325__setup("root=", root_dev_setup);
326
327static int __init rootwait_setup(char *str)
328{
329	if (*str)
330		return 0;
331	root_wait = 1;
332	return 1;
333}
334
335__setup("rootwait", rootwait_setup);
336
337static char * __initdata root_mount_data;
338static int __init root_data_setup(char *str)
339{
340	root_mount_data = str;
341	return 1;
342}
343
344static char * __initdata root_fs_names;
345static int __init fs_names_setup(char *str)
346{
347	root_fs_names = str;
348	return 1;
349}
350
351static unsigned int __initdata root_delay;
352static int __init root_delay_setup(char *str)
353{
354	root_delay = simple_strtoul(str, NULL, 0);
355	return 1;
356}
357
358__setup("rootflags=", root_data_setup);
359__setup("rootfstype=", fs_names_setup);
360__setup("rootdelay=", root_delay_setup);
361
362static void __init get_fs_names(char *page)
363{
364	char *s = page;
365
366	if (root_fs_names) {
367		strcpy(page, root_fs_names);
368		while (*s++) {
369			if (s[-1] == ',')
370				s[-1] = '\0';
371		}
372	} else {
373		int len = get_filesystem_list(page);
374		char *p, *next;
375
376		page[len] = '\0';
377		for (p = page-1; p; p = next) {
378			next = strchr(++p, '\n');
379			if (*p++ != '\t')
380				continue;
381			while ((*s++ = *p++) != '\n')
382				;
383			s[-1] = '\0';
384		}
385	}
386	*s = '\0';
387}
388
389static int __init do_mount_root(const char *name, const char *fs,
390				 const int flags, const void *data)
391{
392	struct super_block *s;
393	struct page *p = NULL;
394	char *data_page = NULL;
395	int ret;
396
397	if (data) {
398		/* init_mount() requires a full page as fifth argument */
399		p = alloc_page(GFP_KERNEL);
400		if (!p)
401			return -ENOMEM;
402		data_page = page_address(p);
403		/* zero-pad. init_mount() will make sure it's terminated */
404		strncpy(data_page, data, PAGE_SIZE);
405	}
406
407	ret = init_mount(name, "/root", fs, flags, data_page);
408	if (ret)
409		goto out;
410
411	init_chdir("/root");
412	s = current->fs->pwd.dentry->d_sb;
413	ROOT_DEV = s->s_dev;
414	printk(KERN_INFO
415	       "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
416	       s->s_type->name,
417	       sb_rdonly(s) ? " readonly" : "",
418	       MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
419
420out:
421	if (p)
422		put_page(p);
423	return ret;
424}
425
426void __init mount_block_root(char *name, int flags)
427{
428	struct page *page = alloc_page(GFP_KERNEL);
429	char *fs_names = page_address(page);
430	char *p;
431	char b[BDEVNAME_SIZE];
432
433	scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)",
434		  MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
435	get_fs_names(fs_names);
436retry:
437	for (p = fs_names; *p; p += strlen(p)+1) {
438		int err = do_mount_root(name, p, flags, root_mount_data);
439		switch (err) {
440			case 0:
441				goto out;
442			case -EACCES:
443			case -EINVAL:
444				continue;
445		}
446	        /*
447		 * Allow the user to distinguish between failed sys_open
448		 * and bad superblock on root device.
449		 * and give them a list of the available devices
450		 */
451		printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
452				root_device_name, b, err);
453		printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
454
455		printk_all_partitions();
456#ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
457		printk("DEBUG_BLOCK_EXT_DEVT is enabled, you need to specify "
458		       "explicit textual name for \"root=\" boot option.\n");
459#endif
460		panic("VFS: Unable to mount root fs on %s", b);
461	}
462	if (!(flags & SB_RDONLY)) {
463		flags |= SB_RDONLY;
464		goto retry;
465	}
466
467	printk("List of all partitions:\n");
468	printk_all_partitions();
469	printk("No filesystem could mount root, tried: ");
470	for (p = fs_names; *p; p += strlen(p)+1)
471		printk(" %s", p);
472	printk("\n");
473	panic("VFS: Unable to mount root fs on %s", b);
474out:
475	put_page(page);
476}
477 
478#ifdef CONFIG_ROOT_NFS
479
480#define NFSROOT_TIMEOUT_MIN	5
481#define NFSROOT_TIMEOUT_MAX	30
482#define NFSROOT_RETRY_MAX	5
483
484static int __init mount_nfs_root(void)
485{
486	char *root_dev, *root_data;
487	unsigned int timeout;
488	int try, err;
489
490	err = nfs_root_data(&root_dev, &root_data);
491	if (err != 0)
492		return 0;
493
494	/*
495	 * The server or network may not be ready, so try several
496	 * times.  Stop after a few tries in case the client wants
497	 * to fall back to other boot methods.
498	 */
499	timeout = NFSROOT_TIMEOUT_MIN;
500	for (try = 1; ; try++) {
501		err = do_mount_root(root_dev, "nfs",
502					root_mountflags, root_data);
503		if (err == 0)
504			return 1;
505		if (try > NFSROOT_RETRY_MAX)
506			break;
507
508		/* Wait, in case the server refused us immediately */
509		ssleep(timeout);
510		timeout <<= 1;
511		if (timeout > NFSROOT_TIMEOUT_MAX)
512			timeout = NFSROOT_TIMEOUT_MAX;
513	}
514	return 0;
515}
516#endif
517
518#ifdef CONFIG_CIFS_ROOT
519
520extern int cifs_root_data(char **dev, char **opts);
521
522#define CIFSROOT_TIMEOUT_MIN	5
523#define CIFSROOT_TIMEOUT_MAX	30
524#define CIFSROOT_RETRY_MAX	5
525
526static int __init mount_cifs_root(void)
527{
528	char *root_dev, *root_data;
529	unsigned int timeout;
530	int try, err;
531
532	err = cifs_root_data(&root_dev, &root_data);
533	if (err != 0)
534		return 0;
535
536	timeout = CIFSROOT_TIMEOUT_MIN;
537	for (try = 1; ; try++) {
538		err = do_mount_root(root_dev, "cifs", root_mountflags,
539				    root_data);
540		if (err == 0)
541			return 1;
542		if (try > CIFSROOT_RETRY_MAX)
543			break;
544
545		ssleep(timeout);
546		timeout <<= 1;
547		if (timeout > CIFSROOT_TIMEOUT_MAX)
548			timeout = CIFSROOT_TIMEOUT_MAX;
549	}
550	return 0;
551}
552#endif
553
554void __init mount_root(void)
555{
556#ifdef CONFIG_ROOT_NFS
557	if (ROOT_DEV == Root_NFS) {
558		if (!mount_nfs_root())
559			printk(KERN_ERR "VFS: Unable to mount root fs via NFS.\n");
560		return;
561	}
562#endif
563#ifdef CONFIG_CIFS_ROOT
564	if (ROOT_DEV == Root_CIFS) {
565		if (!mount_cifs_root())
566			printk(KERN_ERR "VFS: Unable to mount root fs via SMB.\n");
567		return;
568	}
569#endif
570#ifdef CONFIG_BLOCK
571	{
572		int err = create_dev("/dev/root", ROOT_DEV);
573
574		if (err < 0)
575			pr_emerg("Failed to create /dev/root: %d\n", err);
576		mount_block_root("/dev/root", root_mountflags);
577	}
578#endif
579}
580
581/*
582 * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
583 */
584void __init prepare_namespace(void)
585{
586	if (root_delay) {
587		printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
588		       root_delay);
589		ssleep(root_delay);
590	}
591
592	/*
593	 * wait for the known devices to complete their probing
594	 *
595	 * Note: this is a potential source of long boot delays.
596	 * For example, it is not atypical to wait 5 seconds here
597	 * for the touchpad of a laptop to initialize.
598	 */
599	wait_for_device_probe();
600
601	md_run_setup();
602
603	if (saved_root_name[0]) {
604		root_device_name = saved_root_name;
605		if (!strncmp(root_device_name, "mtd", 3) ||
606		    !strncmp(root_device_name, "ubi", 3)) {
607			mount_block_root(root_device_name, root_mountflags);
608			goto out;
609		}
610		ROOT_DEV = name_to_dev_t(root_device_name);
611		if (strncmp(root_device_name, "/dev/", 5) == 0)
612			root_device_name += 5;
613	}
614
615	if (initrd_load())
616		goto out;
617
618	/* wait for any asynchronous scanning to complete */
619	if ((ROOT_DEV == 0) && root_wait) {
620		printk(KERN_INFO "Waiting for root device %s...\n",
621			saved_root_name);
622		while (driver_probe_done() != 0 ||
623			(ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
624			msleep(5);
625		async_synchronize_full();
626	}
627
628	mount_root();
629out:
630	devtmpfs_mount();
631	init_mount(".", "/", NULL, MS_MOVE, NULL);
632	init_chroot(".");
633}
634
635static bool is_tmpfs;
636static int rootfs_init_fs_context(struct fs_context *fc)
637{
638	if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
639		return shmem_init_fs_context(fc);
640
641	return ramfs_init_fs_context(fc);
642}
643
644struct file_system_type rootfs_fs_type = {
645	.name		= "rootfs",
646	.init_fs_context = rootfs_init_fs_context,
647	.kill_sb	= kill_litter_super,
648};
649
650void __init init_rootfs(void)
651{
652	if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
653		(!root_fs_names || strstr(root_fs_names, "tmpfs")))
654		is_tmpfs = true;
655}