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 struct block_device *bdev = dev_to_bdev(dev);
80 const struct uuidcmp *cmp = data;
82 if (!bdev->bd_meta_info ||
83 strncasecmp(cmp->uuid, bdev->bd_meta_info->uuid, cmp->len))
89 * devt_from_partuuid - looks up the dev_t of a partition by its UUID
90 * @uuid_str: char array containing ascii UUID
92 * The function will return the first partition which contains a matching
93 * UUID value in its partition_meta_info struct. This does not search
94 * by filesystem UUIDs.
96 * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be
97 * extracted and used as an offset from the partition identified by the UUID.
99 * Returns the matching dev_t on success or 0 on failure.
101 static dev_t devt_from_partuuid(const char *uuid_str)
104 struct device *dev = NULL;
111 slash = strchr(uuid_str, '/');
112 /* Check for optional partition number offset attributes. */
116 /* Explicitly fail on poor PARTUUID syntax. */
117 if (sscanf(slash + 1, "PARTNROFF=%d%c", &offset, &c) != 1)
118 goto clear_root_wait;
119 cmp.len = slash - uuid_str;
121 cmp.len = strlen(uuid_str);
125 goto clear_root_wait;
127 dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);
133 * Attempt to find the requested partition by adding an offset
134 * to the partition number found by UUID.
136 devt = part_devt(dev_to_disk(dev),
137 dev_to_bdev(dev)->bd_partno + offset);
146 pr_err("VFS: PARTUUID= is invalid.\n"
147 "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
149 pr_err("Disabling rootwait; root= is invalid.\n");
155 * match_dev_by_label - callback for finding a partition using its label
156 * @dev: device passed in by the caller
157 * @data: opaque pointer to the label to match
159 * Returns 1 if the device matches, and 0 otherwise.
161 static int match_dev_by_label(struct device *dev, const void *data)
163 struct block_device *bdev = dev_to_bdev(dev);
164 const char *label = data;
166 if (!bdev->bd_meta_info || strcmp(label, bdev->bd_meta_info->volname))
171 static dev_t devt_from_partlabel(const char *label)
176 dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);
185 static dev_t devt_from_devname(const char *name)
192 if (strlen(name) > 31)
195 for (p = s; *p; p++) {
200 devt = blk_lookup_devt(s, 0);
205 * Try non-existent, but valid partition, which may only exist after
206 * opening the device, like partitioned md devices.
208 while (p > s && isdigit(p[-1]))
210 if (p == s || !*p || *p == '0')
213 /* try disk name without <part number> */
214 part = simple_strtoul(p, NULL, 10);
216 devt = blk_lookup_devt(s, part);
220 /* try disk name without p<part number> */
221 if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
224 return blk_lookup_devt(s, part);
226 #endif /* CONFIG_BLOCK */
228 static dev_t devt_from_devnum(const char *name)
230 unsigned maj, min, offset;
234 if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 ||
235 sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3) {
236 devt = MKDEV(maj, min);
237 if (maj != MAJOR(devt) || min != MINOR(devt))
240 devt = new_decode_dev(simple_strtoul(name, &p, 16));
249 * Convert a name into device number. We accept the following variants:
251 * 1) <hex_major><hex_minor> device number in hexadecimal represents itself
252 * no leading 0x, for example b302.
253 * 2) /dev/nfs represents Root_NFS (0xff)
254 * 3) /dev/<disk_name> represents the device number of disk
255 * 4) /dev/<disk_name><decimal> represents the device number
256 * of partition - device number of disk plus the partition number
257 * 5) /dev/<disk_name>p<decimal> - same as the above, that form is
258 * used when disk name of partitioned disk ends on a digit.
259 * 6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
260 * unique id of a partition if the partition table provides it.
261 * The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
262 * partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
263 * filled hex representation of the 32-bit "NT disk signature", and PP
264 * is a zero-filled hex representation of the 1-based partition number.
265 * 7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
266 * a partition with a known unique id.
267 * 8) <major>:<minor> major and minor number of the device separated by
269 * 9) PARTLABEL=<name> with name being the GPT partition label.
270 * MSDOS partitions do not support labels!
271 * 10) /dev/cifs represents Root_CIFS (0xfe)
273 * If name doesn't have fall into the categories above, we return (0,0).
274 * block_class is used to check if something is a disk name. If the disk
275 * name contains slashes, the device name has them replaced with
278 dev_t name_to_dev_t(const char *name)
280 if (strcmp(name, "/dev/nfs") == 0)
282 if (strcmp(name, "/dev/cifs") == 0)
284 if (strcmp(name, "/dev/ram") == 0)
287 if (strncmp(name, "PARTUUID=", 9) == 0)
288 return devt_from_partuuid(name + 9);
289 if (strncmp(name, "PARTLABEL=", 10) == 0)
290 return devt_from_partlabel(name + 10);
291 if (strncmp(name, "/dev/", 5) == 0)
292 return devt_from_devname(name + 5);
294 return devt_from_devnum(name);
296 EXPORT_SYMBOL_GPL(name_to_dev_t);
298 static int __init root_dev_setup(char *line)
300 strlcpy(saved_root_name, line, sizeof(saved_root_name));
304 __setup("root=", root_dev_setup);
306 static int __init rootwait_setup(char *str)
314 __setup("rootwait", rootwait_setup);
316 static char * __initdata root_mount_data;
317 static int __init root_data_setup(char *str)
319 root_mount_data = str;
323 static char * __initdata root_fs_names;
324 static int __init fs_names_setup(char *str)
330 static unsigned int __initdata root_delay;
331 static int __init root_delay_setup(char *str)
333 root_delay = simple_strtoul(str, NULL, 0);
337 __setup("rootflags=", root_data_setup);
338 __setup("rootfstype=", fs_names_setup);
339 __setup("rootdelay=", root_delay_setup);
341 static int __init split_fs_names(char *page, char *names)
346 strcpy(p, root_fs_names);
353 for (p = page; *p; p += strlen(p)+1)
359 static int __init do_mount_root(const char *name, const char *fs,
360 const int flags, const void *data)
362 struct super_block *s;
363 struct page *p = NULL;
364 char *data_page = NULL;
368 /* init_mount() requires a full page as fifth argument */
369 p = alloc_page(GFP_KERNEL);
372 data_page = page_address(p);
373 /* zero-pad. init_mount() will make sure it's terminated */
374 strncpy(data_page, data, PAGE_SIZE);
377 ret = init_mount(name, "/root", fs, flags, data_page);
382 s = current->fs->pwd.dentry->d_sb;
385 "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
387 sb_rdonly(s) ? " readonly" : "",
388 MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
396 void __init mount_block_root(char *name, int flags)
398 struct page *page = alloc_page(GFP_KERNEL);
399 char *fs_names = page_address(page);
401 char b[BDEVNAME_SIZE];
404 scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)",
405 MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
407 num_fs = split_fs_names(fs_names, root_fs_names);
409 num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);
411 for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1) {
412 int err = do_mount_root(name, p, flags, root_mount_data);
421 * Allow the user to distinguish between failed sys_open
422 * and bad superblock on root device.
423 * and give them a list of the available devices
425 printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
426 root_device_name, b, err);
427 printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
429 printk_all_partitions();
430 panic("VFS: Unable to mount root fs on %s", b);
432 if (!(flags & SB_RDONLY)) {
437 printk("List of all partitions:\n");
438 printk_all_partitions();
439 printk("No filesystem could mount root, tried: ");
440 for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
443 panic("VFS: Unable to mount root fs on %s", b);
448 #ifdef CONFIG_ROOT_NFS
450 #define NFSROOT_TIMEOUT_MIN 5
451 #define NFSROOT_TIMEOUT_MAX 30
452 #define NFSROOT_RETRY_MAX 5
454 static int __init mount_nfs_root(void)
456 char *root_dev, *root_data;
457 unsigned int timeout;
460 err = nfs_root_data(&root_dev, &root_data);
465 * The server or network may not be ready, so try several
466 * times. Stop after a few tries in case the client wants
467 * to fall back to other boot methods.
469 timeout = NFSROOT_TIMEOUT_MIN;
470 for (try = 1; ; try++) {
471 err = do_mount_root(root_dev, "nfs",
472 root_mountflags, root_data);
475 if (try > NFSROOT_RETRY_MAX)
478 /* Wait, in case the server refused us immediately */
481 if (timeout > NFSROOT_TIMEOUT_MAX)
482 timeout = NFSROOT_TIMEOUT_MAX;
488 #ifdef CONFIG_CIFS_ROOT
490 extern int cifs_root_data(char **dev, char **opts);
492 #define CIFSROOT_TIMEOUT_MIN 5
493 #define CIFSROOT_TIMEOUT_MAX 30
494 #define CIFSROOT_RETRY_MAX 5
496 static int __init mount_cifs_root(void)
498 char *root_dev, *root_data;
499 unsigned int timeout;
502 err = cifs_root_data(&root_dev, &root_data);
506 timeout = CIFSROOT_TIMEOUT_MIN;
507 for (try = 1; ; try++) {
508 err = do_mount_root(root_dev, "cifs", root_mountflags,
512 if (try > CIFSROOT_RETRY_MAX)
517 if (timeout > CIFSROOT_TIMEOUT_MAX)
518 timeout = CIFSROOT_TIMEOUT_MAX;
524 static bool __init fs_is_nodev(char *fstype)
526 struct file_system_type *fs = get_fs_type(fstype);
530 ret = !(fs->fs_flags & FS_REQUIRES_DEV);
537 static int __init mount_nodev_root(void)
539 char *fs_names, *fstype;
543 fs_names = (void *)__get_free_page(GFP_KERNEL);
546 num_fs = split_fs_names(fs_names, root_fs_names);
548 for (i = 0, fstype = fs_names; i < num_fs;
549 i++, fstype += strlen(fstype) + 1) {
550 if (!fs_is_nodev(fstype))
552 err = do_mount_root(root_device_name, fstype, root_mountflags,
556 if (err != -EACCES && err != -EINVAL)
557 panic("VFS: Unable to mount root \"%s\" (%s), err=%d\n",
558 root_device_name, fstype, err);
561 free_page((unsigned long)fs_names);
565 void __init mount_root(void)
567 #ifdef CONFIG_ROOT_NFS
568 if (ROOT_DEV == Root_NFS) {
569 if (!mount_nfs_root())
570 printk(KERN_ERR "VFS: Unable to mount root fs via NFS.\n");
574 #ifdef CONFIG_CIFS_ROOT
575 if (ROOT_DEV == Root_CIFS) {
576 if (!mount_cifs_root())
577 printk(KERN_ERR "VFS: Unable to mount root fs via SMB.\n");
581 if (ROOT_DEV == 0 && root_device_name && root_fs_names) {
582 if (mount_nodev_root() == 0)
587 int err = create_dev("/dev/root", ROOT_DEV);
590 pr_emerg("Failed to create /dev/root: %d\n", err);
591 mount_block_root("/dev/root", root_mountflags);
597 * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
599 void __init prepare_namespace(void)
602 printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
608 * wait for the known devices to complete their probing
610 * Note: this is a potential source of long boot delays.
611 * For example, it is not atypical to wait 5 seconds here
612 * for the touchpad of a laptop to initialize.
614 wait_for_device_probe();
618 if (saved_root_name[0]) {
619 root_device_name = saved_root_name;
620 if (!strncmp(root_device_name, "mtd", 3) ||
621 !strncmp(root_device_name, "ubi", 3)) {
622 mount_block_root(root_device_name, root_mountflags);
625 ROOT_DEV = name_to_dev_t(root_device_name);
626 if (strncmp(root_device_name, "/dev/", 5) == 0)
627 root_device_name += 5;
633 /* wait for any asynchronous scanning to complete */
634 if ((ROOT_DEV == 0) && root_wait) {
635 printk(KERN_INFO "Waiting for root device %s...\n",
637 while (driver_probe_done() != 0 ||
638 (ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
640 async_synchronize_full();
646 init_mount(".", "/", NULL, MS_MOVE, NULL);
650 static bool is_tmpfs;
651 static int rootfs_init_fs_context(struct fs_context *fc)
653 if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
654 return shmem_init_fs_context(fc);
656 return ramfs_init_fs_context(fc);
659 struct file_system_type rootfs_fs_type = {
661 .init_fs_context = rootfs_init_fs_context,
662 .kill_sb = kill_litter_super,
665 void __init init_rootfs(void)
667 if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
668 (!root_fs_names || strstr(root_fs_names, "tmpfs")))