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))
94 * devt_from_partuuid - looks up the dev_t of a partition by its UUID
95 * @uuid_str: char array containing ascii UUID
97 * The function will return the first partition which contains a matching
98 * UUID value in its partition_meta_info struct. This does not search
99 * by filesystem UUIDs.
101 * If @uuid_str is followed by a "/PARTNROFF=%d", then the number will be
102 * extracted and used as an offset from the partition identified by the UUID.
104 * Returns the matching dev_t on success or 0 on failure.
106 static dev_t devt_from_partuuid(const char *uuid_str)
109 struct device *dev = NULL;
116 slash = strchr(uuid_str, '/');
117 /* Check for optional partition number offset attributes. */
121 /* Explicitly fail on poor PARTUUID syntax. */
122 if (sscanf(slash + 1, "PARTNROFF=%d%c", &offset, &c) != 1)
123 goto clear_root_wait;
124 cmp.len = slash - uuid_str;
126 cmp.len = strlen(uuid_str);
130 goto clear_root_wait;
132 dev = class_find_device(&block_class, NULL, &cmp, &match_dev_by_uuid);
138 * Attempt to find the requested partition by adding an offset
139 * to the partition number found by UUID.
141 struct hd_struct *part;
143 part = disk_get_part(dev_to_disk(dev),
144 dev_to_part(dev)->partno + offset);
146 devt = part_devt(part);
147 put_device(part_to_dev(part));
157 pr_err("VFS: PARTUUID= is invalid.\n"
158 "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
160 pr_err("Disabling rootwait; root= is invalid.\n");
166 * match_dev_by_label - callback for finding a partition using its label
167 * @dev: device passed in by the caller
168 * @data: opaque pointer to the label to match
170 * Returns 1 if the device matches, and 0 otherwise.
172 static int match_dev_by_label(struct device *dev, const void *data)
174 const char *label = data;
175 struct hd_struct *part = dev_to_part(dev);
177 if (part->info && !strcmp(label, part->info->volname))
183 static dev_t devt_from_partlabel(const char *label)
188 dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);
197 static dev_t devt_from_devname(const char *name)
204 if (strlen(name) > 31)
207 for (p = s; *p; p++) {
212 devt = blk_lookup_devt(s, 0);
217 * Try non-existent, but valid partition, which may only exist after
218 * opening the device, like partitioned md devices.
220 while (p > s && isdigit(p[-1]))
222 if (p == s || !*p || *p == '0')
225 /* try disk name without <part number> */
226 part = simple_strtoul(p, NULL, 10);
228 devt = blk_lookup_devt(s, part);
232 /* try disk name without p<part number> */
233 if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
236 return blk_lookup_devt(s, part);
238 #endif /* CONFIG_BLOCK */
240 static dev_t devt_from_devnum(const char *name)
242 unsigned maj, min, offset;
246 if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 ||
247 sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3) {
248 devt = MKDEV(maj, min);
249 if (maj != MAJOR(devt) || min != MINOR(devt))
252 devt = new_decode_dev(simple_strtoul(name, &p, 16));
261 * Convert a name into device number. We accept the following variants:
263 * 1) <hex_major><hex_minor> device number in hexadecimal represents itself
264 * no leading 0x, for example b302.
265 * 2) /dev/nfs represents Root_NFS (0xff)
266 * 3) /dev/<disk_name> represents the device number of disk
267 * 4) /dev/<disk_name><decimal> represents the device number
268 * of partition - device number of disk plus the partition number
269 * 5) /dev/<disk_name>p<decimal> - same as the above, that form is
270 * used when disk name of partitioned disk ends on a digit.
271 * 6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
272 * unique id of a partition if the partition table provides it.
273 * The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
274 * partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
275 * filled hex representation of the 32-bit "NT disk signature", and PP
276 * is a zero-filled hex representation of the 1-based partition number.
277 * 7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
278 * a partition with a known unique id.
279 * 8) <major>:<minor> major and minor number of the device separated by
281 * 9) PARTLABEL=<name> with name being the GPT partition label.
282 * MSDOS partitions do not support labels!
283 * 10) /dev/cifs represents Root_CIFS (0xfe)
285 * If name doesn't have fall into the categories above, we return (0,0).
286 * block_class is used to check if something is a disk name. If the disk
287 * name contains slashes, the device name has them replaced with
290 dev_t name_to_dev_t(const char *name)
292 if (strcmp(name, "/dev/nfs") == 0)
294 if (strcmp(name, "/dev/cifs") == 0)
296 if (strcmp(name, "/dev/ram") == 0)
299 if (strncmp(name, "PARTUUID=", 9) == 0)
300 return devt_from_partuuid(name + 9);
301 if (strncmp(name, "PARTLABEL=", 10) == 0)
302 return devt_from_partlabel(name + 10);
303 if (strncmp(name, "/dev/", 5) == 0)
304 return devt_from_devname(name + 5);
306 return devt_from_devnum(name);
308 EXPORT_SYMBOL_GPL(name_to_dev_t);
310 static int __init root_dev_setup(char *line)
312 strlcpy(saved_root_name, line, sizeof(saved_root_name));
316 __setup("root=", root_dev_setup);
318 static int __init rootwait_setup(char *str)
326 __setup("rootwait", rootwait_setup);
328 static char * __initdata root_mount_data;
329 static int __init root_data_setup(char *str)
331 root_mount_data = str;
335 static char * __initdata root_fs_names;
336 static int __init fs_names_setup(char *str)
342 static unsigned int __initdata root_delay;
343 static int __init root_delay_setup(char *str)
345 root_delay = simple_strtoul(str, NULL, 0);
349 __setup("rootflags=", root_data_setup);
350 __setup("rootfstype=", fs_names_setup);
351 __setup("rootdelay=", root_delay_setup);
353 static void __init get_fs_names(char *page)
358 strcpy(page, root_fs_names);
364 int len = get_filesystem_list(page);
368 for (p = page-1; p; p = next) {
369 next = strchr(++p, '\n');
372 while ((*s++ = *p++) != '\n')
380 static int __init do_mount_root(const char *name, const char *fs,
381 const int flags, const void *data)
383 struct super_block *s;
384 struct page *p = NULL;
385 char *data_page = NULL;
389 /* init_mount() requires a full page as fifth argument */
390 p = alloc_page(GFP_KERNEL);
393 data_page = page_address(p);
394 /* zero-pad. init_mount() will make sure it's terminated */
395 strncpy(data_page, data, PAGE_SIZE);
398 ret = init_mount(name, "/root", fs, flags, data_page);
403 s = current->fs->pwd.dentry->d_sb;
406 "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
408 sb_rdonly(s) ? " readonly" : "",
409 MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
417 void __init mount_block_root(char *name, int flags)
419 struct page *page = alloc_page(GFP_KERNEL);
420 char *fs_names = page_address(page);
422 char b[BDEVNAME_SIZE];
424 scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)",
425 MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
426 get_fs_names(fs_names);
428 for (p = fs_names; *p; p += strlen(p)+1) {
429 int err = do_mount_root(name, p, flags, root_mount_data);
438 * Allow the user to distinguish between failed sys_open
439 * and bad superblock on root device.
440 * and give them a list of the available devices
442 printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
443 root_device_name, b, err);
444 printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
446 printk_all_partitions();
447 #ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
448 printk("DEBUG_BLOCK_EXT_DEVT is enabled, you need to specify "
449 "explicit textual name for \"root=\" boot option.\n");
451 panic("VFS: Unable to mount root fs on %s", b);
453 if (!(flags & SB_RDONLY)) {
458 printk("List of all partitions:\n");
459 printk_all_partitions();
460 printk("No filesystem could mount root, tried: ");
461 for (p = fs_names; *p; p += strlen(p)+1)
464 panic("VFS: Unable to mount root fs on %s", b);
469 #ifdef CONFIG_ROOT_NFS
471 #define NFSROOT_TIMEOUT_MIN 5
472 #define NFSROOT_TIMEOUT_MAX 30
473 #define NFSROOT_RETRY_MAX 5
475 static int __init mount_nfs_root(void)
477 char *root_dev, *root_data;
478 unsigned int timeout;
481 err = nfs_root_data(&root_dev, &root_data);
486 * The server or network may not be ready, so try several
487 * times. Stop after a few tries in case the client wants
488 * to fall back to other boot methods.
490 timeout = NFSROOT_TIMEOUT_MIN;
491 for (try = 1; ; try++) {
492 err = do_mount_root(root_dev, "nfs",
493 root_mountflags, root_data);
496 if (try > NFSROOT_RETRY_MAX)
499 /* Wait, in case the server refused us immediately */
502 if (timeout > NFSROOT_TIMEOUT_MAX)
503 timeout = NFSROOT_TIMEOUT_MAX;
509 #ifdef CONFIG_CIFS_ROOT
511 extern int cifs_root_data(char **dev, char **opts);
513 #define CIFSROOT_TIMEOUT_MIN 5
514 #define CIFSROOT_TIMEOUT_MAX 30
515 #define CIFSROOT_RETRY_MAX 5
517 static int __init mount_cifs_root(void)
519 char *root_dev, *root_data;
520 unsigned int timeout;
523 err = cifs_root_data(&root_dev, &root_data);
527 timeout = CIFSROOT_TIMEOUT_MIN;
528 for (try = 1; ; try++) {
529 err = do_mount_root(root_dev, "cifs", root_mountflags,
533 if (try > CIFSROOT_RETRY_MAX)
538 if (timeout > CIFSROOT_TIMEOUT_MAX)
539 timeout = CIFSROOT_TIMEOUT_MAX;
545 void __init mount_root(void)
547 #ifdef CONFIG_ROOT_NFS
548 if (ROOT_DEV == Root_NFS) {
549 if (!mount_nfs_root())
550 printk(KERN_ERR "VFS: Unable to mount root fs via NFS.\n");
554 #ifdef CONFIG_CIFS_ROOT
555 if (ROOT_DEV == Root_CIFS) {
556 if (!mount_cifs_root())
557 printk(KERN_ERR "VFS: Unable to mount root fs via SMB.\n");
563 int err = create_dev("/dev/root", ROOT_DEV);
566 pr_emerg("Failed to create /dev/root: %d\n", err);
567 mount_block_root("/dev/root", root_mountflags);
573 * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
575 void __init prepare_namespace(void)
578 printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
584 * wait for the known devices to complete their probing
586 * Note: this is a potential source of long boot delays.
587 * For example, it is not atypical to wait 5 seconds here
588 * for the touchpad of a laptop to initialize.
590 wait_for_device_probe();
594 if (saved_root_name[0]) {
595 root_device_name = saved_root_name;
596 if (!strncmp(root_device_name, "mtd", 3) ||
597 !strncmp(root_device_name, "ubi", 3)) {
598 mount_block_root(root_device_name, root_mountflags);
601 ROOT_DEV = name_to_dev_t(root_device_name);
602 if (strncmp(root_device_name, "/dev/", 5) == 0)
603 root_device_name += 5;
609 /* wait for any asynchronous scanning to complete */
610 if ((ROOT_DEV == 0) && root_wait) {
611 printk(KERN_INFO "Waiting for root device %s...\n",
613 while (driver_probe_done() != 0 ||
614 (ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
616 async_synchronize_full();
622 init_mount(".", "/", NULL, MS_MOVE, NULL);
626 static bool is_tmpfs;
627 static int rootfs_init_fs_context(struct fs_context *fc)
629 if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
630 return shmem_init_fs_context(fc);
632 return ramfs_init_fs_context(fc);
635 struct file_system_type rootfs_fs_type = {
637 .init_fs_context = rootfs_init_fs_context,
638 .kill_sb = kill_litter_super,
641 void __init init_rootfs(void)
643 if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
644 (!root_fs_names || strstr(root_fs_names, "tmpfs")))