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/mount.h>
12 #include <linux/device.h>
13 #include <linux/init.h>
15 #include <linux/initrd.h>
16 #include <linux/async.h>
17 #include <linux/fs_struct.h>
18 #include <linux/slab.h>
19 #include <linux/ramfs.h>
20 #include <linux/shmem_fs.h>
22 #include <linux/nfs_fs.h>
23 #include <linux/nfs_fs_sb.h>
24 #include <linux/nfs_mount.h>
25 #include <linux/raid/detect.h>
26 #include <uapi/linux/mount.h>
28 #include "do_mounts.h"
30 int root_mountflags
= MS_RDONLY
| MS_SILENT
;
31 static char * __initdata root_device_name
;
32 static char __initdata saved_root_name
[64];
37 static int __init
load_ramdisk(char *str
)
39 pr_warn("ignoring the deprecated load_ramdisk= option\n");
42 __setup("load_ramdisk=", load_ramdisk
);
44 static int __init
readonly(char *str
)
48 root_mountflags
|= MS_RDONLY
;
52 static int __init
readwrite(char *str
)
56 root_mountflags
&= ~MS_RDONLY
;
60 __setup("ro", readonly
);
61 __setup("rw", readwrite
);
70 * match_dev_by_uuid - callback for finding a partition using its uuid
71 * @dev: device passed in by the caller
72 * @data: opaque pointer to the desired struct uuidcmp to match
74 * Returns 1 if the device matches, and 0 otherwise.
76 static int match_dev_by_uuid(struct device
*dev
, const void *data
)
78 struct block_device
*bdev
= dev_to_bdev(dev
);
79 const struct uuidcmp
*cmp
= data
;
81 if (!bdev
->bd_meta_info
||
82 strncasecmp(cmp
->uuid
, bdev
->bd_meta_info
->uuid
, cmp
->len
))
88 * devt_from_partuuid - looks up the dev_t of a partition by its UUID
89 * @uuid_str: char array containing ascii UUID
91 * The function will return the first partition which contains a matching
92 * UUID value in its partition_meta_info struct. This does not search
93 * by filesystem UUIDs.
95 * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be
96 * extracted and used as an offset from the partition identified by the UUID.
98 * Returns the matching dev_t on success or 0 on failure.
100 static dev_t
devt_from_partuuid(const char *uuid_str
)
103 struct device
*dev
= NULL
;
110 slash
= strchr(uuid_str
, '/');
111 /* Check for optional partition number offset attributes. */
115 /* Explicitly fail on poor PARTUUID syntax. */
116 if (sscanf(slash
+ 1, "PARTNROFF=%d%c", &offset
, &c
) != 1)
117 goto clear_root_wait
;
118 cmp
.len
= slash
- uuid_str
;
120 cmp
.len
= strlen(uuid_str
);
124 goto clear_root_wait
;
126 dev
= class_find_device(&block_class
, NULL
, &cmp
, &match_dev_by_uuid
);
132 * Attempt to find the requested partition by adding an offset
133 * to the partition number found by UUID.
135 devt
= part_devt(dev_to_disk(dev
),
136 dev_to_bdev(dev
)->bd_partno
+ offset
);
145 pr_err("VFS: PARTUUID= is invalid.\n"
146 "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
148 pr_err("Disabling rootwait; root= is invalid.\n");
154 * match_dev_by_label - callback for finding a partition using its label
155 * @dev: device passed in by the caller
156 * @data: opaque pointer to the label to match
158 * Returns 1 if the device matches, and 0 otherwise.
160 static int match_dev_by_label(struct device
*dev
, const void *data
)
162 struct block_device
*bdev
= dev_to_bdev(dev
);
163 const char *label
= data
;
165 if (!bdev
->bd_meta_info
|| strcmp(label
, bdev
->bd_meta_info
->volname
))
170 static dev_t
devt_from_partlabel(const char *label
)
175 dev
= class_find_device(&block_class
, NULL
, label
, &match_dev_by_label
);
184 static dev_t
devt_from_devname(const char *name
)
191 if (strlen(name
) > 31)
194 for (p
= s
; *p
; p
++) {
199 devt
= blk_lookup_devt(s
, 0);
204 * Try non-existent, but valid partition, which may only exist after
205 * opening the device, like partitioned md devices.
207 while (p
> s
&& isdigit(p
[-1]))
209 if (p
== s
|| !*p
|| *p
== '0')
212 /* try disk name without <part number> */
213 part
= simple_strtoul(p
, NULL
, 10);
215 devt
= blk_lookup_devt(s
, part
);
219 /* try disk name without p<part number> */
220 if (p
< s
+ 2 || !isdigit(p
[-2]) || p
[-1] != 'p')
223 return blk_lookup_devt(s
, part
);
225 #endif /* CONFIG_BLOCK */
227 static dev_t
devt_from_devnum(const char *name
)
229 unsigned maj
, min
, offset
;
233 if (sscanf(name
, "%u:%u%c", &maj
, &min
, &dummy
) == 2 ||
234 sscanf(name
, "%u:%u:%u:%c", &maj
, &min
, &offset
, &dummy
) == 3) {
235 devt
= MKDEV(maj
, min
);
236 if (maj
!= MAJOR(devt
) || min
!= MINOR(devt
))
239 devt
= new_decode_dev(simple_strtoul(name
, &p
, 16));
248 * Convert a name into device number. We accept the following variants:
250 * 1) <hex_major><hex_minor> device number in hexadecimal represents itself
251 * no leading 0x, for example b302.
252 * 2) /dev/nfs represents Root_NFS (0xff)
253 * 3) /dev/<disk_name> represents the device number of disk
254 * 4) /dev/<disk_name><decimal> represents the device number
255 * of partition - device number of disk plus the partition number
256 * 5) /dev/<disk_name>p<decimal> - same as the above, that form is
257 * used when disk name of partitioned disk ends on a digit.
258 * 6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
259 * unique id of a partition if the partition table provides it.
260 * The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
261 * partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
262 * filled hex representation of the 32-bit "NT disk signature", and PP
263 * is a zero-filled hex representation of the 1-based partition number.
264 * 7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
265 * a partition with a known unique id.
266 * 8) <major>:<minor> major and minor number of the device separated by
268 * 9) PARTLABEL=<name> with name being the GPT partition label.
269 * MSDOS partitions do not support labels!
270 * 10) /dev/cifs represents Root_CIFS (0xfe)
272 * If name doesn't have fall into the categories above, we return (0,0).
273 * block_class is used to check if something is a disk name. If the disk
274 * name contains slashes, the device name has them replaced with
277 dev_t
name_to_dev_t(const char *name
)
279 if (strcmp(name
, "/dev/nfs") == 0)
281 if (strcmp(name
, "/dev/cifs") == 0)
283 if (strcmp(name
, "/dev/ram") == 0)
286 if (strncmp(name
, "PARTUUID=", 9) == 0)
287 return devt_from_partuuid(name
+ 9);
288 if (strncmp(name
, "PARTLABEL=", 10) == 0)
289 return devt_from_partlabel(name
+ 10);
290 if (strncmp(name
, "/dev/", 5) == 0)
291 return devt_from_devname(name
+ 5);
293 return devt_from_devnum(name
);
295 EXPORT_SYMBOL_GPL(name_to_dev_t
);
297 static int __init
root_dev_setup(char *line
)
299 strlcpy(saved_root_name
, line
, sizeof(saved_root_name
));
303 __setup("root=", root_dev_setup
);
305 static int __init
rootwait_setup(char *str
)
313 __setup("rootwait", rootwait_setup
);
315 static char * __initdata root_mount_data
;
316 static int __init
root_data_setup(char *str
)
318 root_mount_data
= str
;
322 static char * __initdata root_fs_names
;
323 static int __init
fs_names_setup(char *str
)
329 static unsigned int __initdata root_delay
;
330 static int __init
root_delay_setup(char *str
)
332 root_delay
= simple_strtoul(str
, NULL
, 0);
336 __setup("rootflags=", root_data_setup
);
337 __setup("rootfstype=", fs_names_setup
);
338 __setup("rootdelay=", root_delay_setup
);
340 /* This can return zero length strings. Caller should check */
341 static int __init
split_fs_names(char *page
, size_t size
, char *names
)
346 strlcpy(p
, root_fs_names
, size
);
357 static int __init
do_mount_root(const char *name
, const char *fs
,
358 const int flags
, const void *data
)
360 struct super_block
*s
;
361 struct page
*p
= NULL
;
362 char *data_page
= NULL
;
366 /* init_mount() requires a full page as fifth argument */
367 p
= alloc_page(GFP_KERNEL
);
370 data_page
= page_address(p
);
371 /* zero-pad. init_mount() will make sure it's terminated */
372 strncpy(data_page
, data
, PAGE_SIZE
);
375 ret
= init_mount(name
, "/root", fs
, flags
, data_page
);
380 s
= current
->fs
->pwd
.dentry
->d_sb
;
383 "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
385 sb_rdonly(s
) ? " readonly" : "",
386 MAJOR(ROOT_DEV
), MINOR(ROOT_DEV
));
394 void __init
mount_block_root(char *name
, int flags
)
396 struct page
*page
= alloc_page(GFP_KERNEL
);
397 char *fs_names
= page_address(page
);
399 char b
[BDEVNAME_SIZE
];
402 scnprintf(b
, BDEVNAME_SIZE
, "unknown-block(%u,%u)",
403 MAJOR(ROOT_DEV
), MINOR(ROOT_DEV
));
405 num_fs
= split_fs_names(fs_names
, PAGE_SIZE
, root_fs_names
);
407 num_fs
= list_bdev_fs_names(fs_names
, PAGE_SIZE
);
409 for (i
= 0, p
= fs_names
; i
< num_fs
; i
++, p
+= strlen(p
)+1) {
414 err
= do_mount_root(name
, p
, flags
, root_mount_data
);
423 * Allow the user to distinguish between failed sys_open
424 * and bad superblock on root device.
425 * and give them a list of the available devices
427 printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
428 root_device_name
, b
, err
);
429 printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
431 printk_all_partitions();
432 panic("VFS: Unable to mount root fs on %s", b
);
434 if (!(flags
& SB_RDONLY
)) {
439 printk("List of all partitions:\n");
440 printk_all_partitions();
441 printk("No filesystem could mount root, tried: ");
442 for (i
= 0, p
= fs_names
; i
< num_fs
; i
++, p
+= strlen(p
)+1)
445 panic("VFS: Unable to mount root fs on %s", b
);
450 #ifdef CONFIG_ROOT_NFS
452 #define NFSROOT_TIMEOUT_MIN 5
453 #define NFSROOT_TIMEOUT_MAX 30
454 #define NFSROOT_RETRY_MAX 5
456 static int __init
mount_nfs_root(void)
458 char *root_dev
, *root_data
;
459 unsigned int timeout
;
462 err
= nfs_root_data(&root_dev
, &root_data
);
467 * The server or network may not be ready, so try several
468 * times. Stop after a few tries in case the client wants
469 * to fall back to other boot methods.
471 timeout
= NFSROOT_TIMEOUT_MIN
;
472 for (try = 1; ; try++) {
473 err
= do_mount_root(root_dev
, "nfs",
474 root_mountflags
, root_data
);
477 if (try > NFSROOT_RETRY_MAX
)
480 /* Wait, in case the server refused us immediately */
483 if (timeout
> NFSROOT_TIMEOUT_MAX
)
484 timeout
= NFSROOT_TIMEOUT_MAX
;
490 #ifdef CONFIG_CIFS_ROOT
492 extern int cifs_root_data(char **dev
, char **opts
);
494 #define CIFSROOT_TIMEOUT_MIN 5
495 #define CIFSROOT_TIMEOUT_MAX 30
496 #define CIFSROOT_RETRY_MAX 5
498 static int __init
mount_cifs_root(void)
500 char *root_dev
, *root_data
;
501 unsigned int timeout
;
504 err
= cifs_root_data(&root_dev
, &root_data
);
508 timeout
= CIFSROOT_TIMEOUT_MIN
;
509 for (try = 1; ; try++) {
510 err
= do_mount_root(root_dev
, "cifs", root_mountflags
,
514 if (try > CIFSROOT_RETRY_MAX
)
519 if (timeout
> CIFSROOT_TIMEOUT_MAX
)
520 timeout
= CIFSROOT_TIMEOUT_MAX
;
526 static bool __init
fs_is_nodev(char *fstype
)
528 struct file_system_type
*fs
= get_fs_type(fstype
);
532 ret
= !(fs
->fs_flags
& FS_REQUIRES_DEV
);
539 static int __init
mount_nodev_root(void)
541 char *fs_names
, *fstype
;
545 fs_names
= (void *)__get_free_page(GFP_KERNEL
);
548 num_fs
= split_fs_names(fs_names
, PAGE_SIZE
, root_fs_names
);
550 for (i
= 0, fstype
= fs_names
; i
< num_fs
;
551 i
++, fstype
+= strlen(fstype
) + 1) {
554 if (!fs_is_nodev(fstype
))
556 err
= do_mount_root(root_device_name
, fstype
, root_mountflags
,
562 free_page((unsigned long)fs_names
);
566 void __init
mount_root(void)
568 #ifdef CONFIG_ROOT_NFS
569 if (ROOT_DEV
== Root_NFS
) {
570 if (!mount_nfs_root())
571 printk(KERN_ERR
"VFS: Unable to mount root fs via NFS.\n");
575 #ifdef CONFIG_CIFS_ROOT
576 if (ROOT_DEV
== Root_CIFS
) {
577 if (!mount_cifs_root())
578 printk(KERN_ERR
"VFS: Unable to mount root fs via SMB.\n");
582 if (ROOT_DEV
== 0 && root_device_name
&& root_fs_names
) {
583 if (mount_nodev_root() == 0)
588 int err
= create_dev("/dev/root", ROOT_DEV
);
591 pr_emerg("Failed to create /dev/root: %d\n", err
);
592 mount_block_root("/dev/root", root_mountflags
);
598 * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
600 void __init
prepare_namespace(void)
603 printk(KERN_INFO
"Waiting %d sec before mounting root device...\n",
609 * wait for the known devices to complete their probing
611 * Note: this is a potential source of long boot delays.
612 * For example, it is not atypical to wait 5 seconds here
613 * for the touchpad of a laptop to initialize.
615 wait_for_device_probe();
619 if (saved_root_name
[0]) {
620 root_device_name
= saved_root_name
;
621 if (!strncmp(root_device_name
, "mtd", 3) ||
622 !strncmp(root_device_name
, "ubi", 3)) {
623 mount_block_root(root_device_name
, root_mountflags
);
626 ROOT_DEV
= name_to_dev_t(root_device_name
);
627 if (strncmp(root_device_name
, "/dev/", 5) == 0)
628 root_device_name
+= 5;
634 /* wait for any asynchronous scanning to complete */
635 if ((ROOT_DEV
== 0) && root_wait
) {
636 printk(KERN_INFO
"Waiting for root device %s...\n",
638 while (driver_probe_done() != 0 ||
639 (ROOT_DEV
= name_to_dev_t(saved_root_name
)) == 0)
641 async_synchronize_full();
647 init_mount(".", "/", NULL
, MS_MOVE
, NULL
);
651 static bool is_tmpfs
;
652 static int rootfs_init_fs_context(struct fs_context
*fc
)
654 if (IS_ENABLED(CONFIG_TMPFS
) && is_tmpfs
)
655 return shmem_init_fs_context(fc
);
657 return ramfs_init_fs_context(fc
);
660 struct file_system_type rootfs_fs_type
= {
662 .init_fs_context
= rootfs_init_fs_context
,
663 .kill_sb
= kill_litter_super
,
666 void __init
init_rootfs(void)
668 if (IS_ENABLED(CONFIG_TMPFS
) && !saved_root_name
[0] &&
669 (!root_fs_names
|| strstr(root_fs_names
, "tmpfs")))