1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/module.h>
3 #include <linux/sched.h>
4 #include <linux/ctype.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>
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>
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>
29 #include "do_mounts.h"
31 int root_mountflags
= MS_RDONLY
| MS_SILENT
;
32 static char * __initdata root_device_name
;
33 static char __initdata saved_root_name
[64];
38 static int __init
load_ramdisk(char *str
)
40 pr_warn("ignoring the deprecated load_ramdisk= option\n");
43 __setup("load_ramdisk=", load_ramdisk
);
45 static int __init
readonly(char *str
)
49 root_mountflags
|= MS_RDONLY
;
53 static int __init
readwrite(char *str
)
57 root_mountflags
&= ~MS_RDONLY
;
61 __setup("ro", readonly
);
62 __setup("rw", readwrite
);
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
75 * Returns 1 if the device matches, and 0 otherwise.
77 static int match_dev_by_uuid(struct device
*dev
, const void *data
)
79 const struct uuidcmp
*cmp
= data
;
80 struct hd_struct
*part
= dev_to_part(dev
);
85 if (strncasecmp(cmp
->uuid
, part
->info
->uuid
, cmp
->len
))
95 * devt_from_partuuid - looks up the dev_t of a partition by its UUID
96 * @uuid_str: char array containing ascii UUID
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.
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.
105 * Returns the matching dev_t on success or 0 on failure.
107 static dev_t
devt_from_partuuid(const char *uuid_str
)
111 struct device
*dev
= NULL
;
112 struct gendisk
*disk
;
113 struct hd_struct
*part
;
115 bool clear_root_wait
= false;
120 slash
= strchr(uuid_str
, '/');
121 /* Check for optional partition number offset attributes. */
124 /* Explicitly fail on poor PARTUUID syntax. */
125 if (sscanf(slash
+ 1,
126 "PARTNROFF=%d%c", &offset
, &c
) != 1) {
127 clear_root_wait
= true;
130 cmp
.len
= slash
- uuid_str
;
132 cmp
.len
= strlen(uuid_str
);
136 clear_root_wait
= true;
140 dev
= class_find_device(&block_class
, NULL
, &cmp
,
147 /* Attempt to find the partition by offset. */
152 disk
= part_to_disk(dev_to_part(dev
));
153 part
= disk_get_part(disk
, dev_to_part(dev
)->partno
+ offset
);
155 res
= part_devt(part
);
156 put_device(part_to_dev(part
));
162 if (clear_root_wait
) {
163 pr_err("VFS: PARTUUID= is invalid.\n"
164 "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
166 pr_err("Disabling rootwait; root= is invalid.\n");
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
177 * Returns 1 if the device matches, and 0 otherwise.
179 static int match_dev_by_label(struct device
*dev
, const void *data
)
181 const char *label
= data
;
182 struct hd_struct
*part
= dev_to_part(dev
);
184 if (part
->info
&& !strcmp(label
, part
->info
->volname
))
192 * Convert a name into device number. We accept the following variants:
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
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)
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
222 dev_t
name_to_dev_t(const char *name
)
230 if (strncmp(name
, "PARTUUID=", 9) == 0) {
232 res
= devt_from_partuuid(name
);
236 } else if (strncmp(name
, "PARTLABEL=", 10) == 0) {
239 dev
= class_find_device(&block_class
, NULL
, name
+ 10,
240 &match_dev_by_label
);
250 if (strncmp(name
, "/dev/", 5) != 0) {
251 unsigned maj
, min
, offset
;
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
))
260 res
= new_decode_dev(simple_strtoul(name
, &p
, 16));
269 if (strcmp(name
, "nfs") == 0)
272 if (strcmp(name
, "cifs") == 0)
275 if (strcmp(name
, "ram") == 0)
278 if (strlen(name
) > 31)
284 res
= blk_lookup_devt(s
, 0);
289 * try non-existent, but valid partition, which may only exist
290 * after revalidating the disk, like partitioned md devices
292 while (p
> s
&& isdigit(p
[-1]))
294 if (p
== s
|| !*p
|| *p
== '0')
297 /* try disk name without <part number> */
298 part
= simple_strtoul(p
, NULL
, 10);
300 res
= blk_lookup_devt(s
, part
);
304 /* try disk name without p<part number> */
305 if (p
< s
+ 2 || !isdigit(p
[-2]) || p
[-1] != 'p')
308 res
= blk_lookup_devt(s
, part
);
317 EXPORT_SYMBOL_GPL(name_to_dev_t
);
319 static int __init
root_dev_setup(char *line
)
321 strlcpy(saved_root_name
, line
, sizeof(saved_root_name
));
325 __setup("root=", root_dev_setup
);
327 static int __init
rootwait_setup(char *str
)
335 __setup("rootwait", rootwait_setup
);
337 static char * __initdata root_mount_data
;
338 static int __init
root_data_setup(char *str
)
340 root_mount_data
= str
;
344 static char * __initdata root_fs_names
;
345 static int __init
fs_names_setup(char *str
)
351 static unsigned int __initdata root_delay
;
352 static int __init
root_delay_setup(char *str
)
354 root_delay
= simple_strtoul(str
, NULL
, 0);
358 __setup("rootflags=", root_data_setup
);
359 __setup("rootfstype=", fs_names_setup
);
360 __setup("rootdelay=", root_delay_setup
);
362 static void __init
get_fs_names(char *page
)
367 strcpy(page
, root_fs_names
);
373 int len
= get_filesystem_list(page
);
377 for (p
= page
-1; p
; p
= next
) {
378 next
= strchr(++p
, '\n');
381 while ((*s
++ = *p
++) != '\n')
389 static int __init
do_mount_root(const char *name
, const char *fs
,
390 const int flags
, const void *data
)
392 struct super_block
*s
;
393 struct page
*p
= NULL
;
394 char *data_page
= NULL
;
398 /* init_mount() requires a full page as fifth argument */
399 p
= alloc_page(GFP_KERNEL
);
402 data_page
= page_address(p
);
403 /* zero-pad. init_mount() will make sure it's terminated */
404 strncpy(data_page
, data
, PAGE_SIZE
);
407 ret
= init_mount(name
, "/root", fs
, flags
, data_page
);
412 s
= current
->fs
->pwd
.dentry
->d_sb
;
415 "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
417 sb_rdonly(s
) ? " readonly" : "",
418 MAJOR(ROOT_DEV
), MINOR(ROOT_DEV
));
426 void __init
mount_block_root(char *name
, int flags
)
428 struct page
*page
= alloc_page(GFP_KERNEL
);
429 char *fs_names
= page_address(page
);
431 char b
[BDEVNAME_SIZE
];
433 scnprintf(b
, BDEVNAME_SIZE
, "unknown-block(%u,%u)",
434 MAJOR(ROOT_DEV
), MINOR(ROOT_DEV
));
435 get_fs_names(fs_names
);
437 for (p
= fs_names
; *p
; p
+= strlen(p
)+1) {
438 int err
= do_mount_root(name
, p
, flags
, root_mount_data
);
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
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");
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");
460 panic("VFS: Unable to mount root fs on %s", b
);
462 if (!(flags
& SB_RDONLY
)) {
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)
473 panic("VFS: Unable to mount root fs on %s", b
);
478 #ifdef CONFIG_ROOT_NFS
480 #define NFSROOT_TIMEOUT_MIN 5
481 #define NFSROOT_TIMEOUT_MAX 30
482 #define NFSROOT_RETRY_MAX 5
484 static int __init
mount_nfs_root(void)
486 char *root_dev
, *root_data
;
487 unsigned int timeout
;
490 err
= nfs_root_data(&root_dev
, &root_data
);
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.
499 timeout
= NFSROOT_TIMEOUT_MIN
;
500 for (try = 1; ; try++) {
501 err
= do_mount_root(root_dev
, "nfs",
502 root_mountflags
, root_data
);
505 if (try > NFSROOT_RETRY_MAX
)
508 /* Wait, in case the server refused us immediately */
511 if (timeout
> NFSROOT_TIMEOUT_MAX
)
512 timeout
= NFSROOT_TIMEOUT_MAX
;
518 #ifdef CONFIG_CIFS_ROOT
520 extern int cifs_root_data(char **dev
, char **opts
);
522 #define CIFSROOT_TIMEOUT_MIN 5
523 #define CIFSROOT_TIMEOUT_MAX 30
524 #define CIFSROOT_RETRY_MAX 5
526 static int __init
mount_cifs_root(void)
528 char *root_dev
, *root_data
;
529 unsigned int timeout
;
532 err
= cifs_root_data(&root_dev
, &root_data
);
536 timeout
= CIFSROOT_TIMEOUT_MIN
;
537 for (try = 1; ; try++) {
538 err
= do_mount_root(root_dev
, "cifs", root_mountflags
,
542 if (try > CIFSROOT_RETRY_MAX
)
547 if (timeout
> CIFSROOT_TIMEOUT_MAX
)
548 timeout
= CIFSROOT_TIMEOUT_MAX
;
554 void __init
mount_root(void)
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");
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");
572 int err
= create_dev("/dev/root", ROOT_DEV
);
575 pr_emerg("Failed to create /dev/root: %d\n", err
);
576 mount_block_root("/dev/root", root_mountflags
);
582 * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
584 void __init
prepare_namespace(void)
587 printk(KERN_INFO
"Waiting %d sec before mounting root device...\n",
593 * wait for the known devices to complete their probing
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.
599 wait_for_device_probe();
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
);
610 ROOT_DEV
= name_to_dev_t(root_device_name
);
611 if (strncmp(root_device_name
, "/dev/", 5) == 0)
612 root_device_name
+= 5;
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",
622 while (driver_probe_done() != 0 ||
623 (ROOT_DEV
= name_to_dev_t(saved_root_name
)) == 0)
625 async_synchronize_full();
631 init_mount(".", "/", NULL
, MS_MOVE
, NULL
);
635 static bool is_tmpfs
;
636 static int rootfs_init_fs_context(struct fs_context
*fc
)
638 if (IS_ENABLED(CONFIG_TMPFS
) && is_tmpfs
)
639 return shmem_init_fs_context(fc
);
641 return ramfs_init_fs_context(fc
);
644 struct file_system_type rootfs_fs_type
= {
646 .init_fs_context
= rootfs_init_fs_context
,
647 .kill_sb
= kill_litter_super
,
650 void __init
init_rootfs(void)
652 if (IS_ENABLED(CONFIG_TMPFS
) && !saved_root_name
[0] &&
653 (!root_fs_names
|| strstr(root_fs_names
, "tmpfs")))