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);
82 if (!part->bdev->bd_meta_info ||
83 strncasecmp(cmp->uuid, part->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 struct hd_struct *part;
138 part = disk_get_part(dev_to_disk(dev),
139 dev_to_part(dev)->bdev->bd_partno + offset);
141 devt = part_devt(part);
142 put_device(part_to_dev(part));
152 pr_err("VFS: PARTUUID= is invalid.\n"
153 "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
155 pr_err("Disabling rootwait; root= is invalid.\n");
161 * match_dev_by_label - callback for finding a partition using its label
162 * @dev: device passed in by the caller
163 * @data: opaque pointer to the label to match
165 * Returns 1 if the device matches, and 0 otherwise.
167 static int match_dev_by_label(struct device *dev, const void *data)
169 const char *label = data;
170 struct hd_struct *part = dev_to_part(dev);
172 if (!part->bdev->bd_meta_info ||
173 strcmp(label, part->bdev->bd_meta_info->volname))
178 static dev_t devt_from_partlabel(const char *label)
183 dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);
192 static dev_t devt_from_devname(const char *name)
199 if (strlen(name) > 31)
202 for (p = s; *p; p++) {
207 devt = blk_lookup_devt(s, 0);
212 * Try non-existent, but valid partition, which may only exist after
213 * opening the device, like partitioned md devices.
215 while (p > s && isdigit(p[-1]))
217 if (p == s || !*p || *p == '0')
220 /* try disk name without <part number> */
221 part = simple_strtoul(p, NULL, 10);
223 devt = blk_lookup_devt(s, part);
227 /* try disk name without p<part number> */
228 if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
231 return blk_lookup_devt(s, part);
233 #endif /* CONFIG_BLOCK */
235 static dev_t devt_from_devnum(const char *name)
237 unsigned maj, min, offset;
241 if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 ||
242 sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3) {
243 devt = MKDEV(maj, min);
244 if (maj != MAJOR(devt) || min != MINOR(devt))
247 devt = new_decode_dev(simple_strtoul(name, &p, 16));
256 * Convert a name into device number. We accept the following variants:
258 * 1) <hex_major><hex_minor> device number in hexadecimal represents itself
259 * no leading 0x, for example b302.
260 * 2) /dev/nfs represents Root_NFS (0xff)
261 * 3) /dev/<disk_name> represents the device number of disk
262 * 4) /dev/<disk_name><decimal> represents the device number
263 * of partition - device number of disk plus the partition number
264 * 5) /dev/<disk_name>p<decimal> - same as the above, that form is
265 * used when disk name of partitioned disk ends on a digit.
266 * 6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
267 * unique id of a partition if the partition table provides it.
268 * The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
269 * partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
270 * filled hex representation of the 32-bit "NT disk signature", and PP
271 * is a zero-filled hex representation of the 1-based partition number.
272 * 7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
273 * a partition with a known unique id.
274 * 8) <major>:<minor> major and minor number of the device separated by
276 * 9) PARTLABEL=<name> with name being the GPT partition label.
277 * MSDOS partitions do not support labels!
278 * 10) /dev/cifs represents Root_CIFS (0xfe)
280 * If name doesn't have fall into the categories above, we return (0,0).
281 * block_class is used to check if something is a disk name. If the disk
282 * name contains slashes, the device name has them replaced with
285 dev_t name_to_dev_t(const char *name)
287 if (strcmp(name, "/dev/nfs") == 0)
289 if (strcmp(name, "/dev/cifs") == 0)
291 if (strcmp(name, "/dev/ram") == 0)
294 if (strncmp(name, "PARTUUID=", 9) == 0)
295 return devt_from_partuuid(name + 9);
296 if (strncmp(name, "PARTLABEL=", 10) == 0)
297 return devt_from_partlabel(name + 10);
298 if (strncmp(name, "/dev/", 5) == 0)
299 return devt_from_devname(name + 5);
301 return devt_from_devnum(name);
303 EXPORT_SYMBOL_GPL(name_to_dev_t);
305 static int __init root_dev_setup(char *line)
307 strlcpy(saved_root_name, line, sizeof(saved_root_name));
311 __setup("root=", root_dev_setup);
313 static int __init rootwait_setup(char *str)
321 __setup("rootwait", rootwait_setup);
323 static char * __initdata root_mount_data;
324 static int __init root_data_setup(char *str)
326 root_mount_data = str;
330 static char * __initdata root_fs_names;
331 static int __init fs_names_setup(char *str)
337 static unsigned int __initdata root_delay;
338 static int __init root_delay_setup(char *str)
340 root_delay = simple_strtoul(str, NULL, 0);
344 __setup("rootflags=", root_data_setup);
345 __setup("rootfstype=", fs_names_setup);
346 __setup("rootdelay=", root_delay_setup);
348 static void __init get_fs_names(char *page)
353 strcpy(page, root_fs_names);
359 int len = get_filesystem_list(page);
363 for (p = page-1; p; p = next) {
364 next = strchr(++p, '\n');
367 while ((*s++ = *p++) != '\n')
375 static int __init do_mount_root(const char *name, const char *fs,
376 const int flags, const void *data)
378 struct super_block *s;
379 struct page *p = NULL;
380 char *data_page = NULL;
384 /* init_mount() requires a full page as fifth argument */
385 p = alloc_page(GFP_KERNEL);
388 data_page = page_address(p);
389 /* zero-pad. init_mount() will make sure it's terminated */
390 strncpy(data_page, data, PAGE_SIZE);
393 ret = init_mount(name, "/root", fs, flags, data_page);
398 s = current->fs->pwd.dentry->d_sb;
401 "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
403 sb_rdonly(s) ? " readonly" : "",
404 MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
412 void __init mount_block_root(char *name, int flags)
414 struct page *page = alloc_page(GFP_KERNEL);
415 char *fs_names = page_address(page);
417 char b[BDEVNAME_SIZE];
419 scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)",
420 MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
421 get_fs_names(fs_names);
423 for (p = fs_names; *p; p += strlen(p)+1) {
424 int err = do_mount_root(name, p, flags, root_mount_data);
433 * Allow the user to distinguish between failed sys_open
434 * and bad superblock on root device.
435 * and give them a list of the available devices
437 printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
438 root_device_name, b, err);
439 printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
441 printk_all_partitions();
442 #ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
443 printk("DEBUG_BLOCK_EXT_DEVT is enabled, you need to specify "
444 "explicit textual name for \"root=\" boot option.\n");
446 panic("VFS: Unable to mount root fs on %s", b);
448 if (!(flags & SB_RDONLY)) {
453 printk("List of all partitions:\n");
454 printk_all_partitions();
455 printk("No filesystem could mount root, tried: ");
456 for (p = fs_names; *p; p += strlen(p)+1)
459 panic("VFS: Unable to mount root fs on %s", b);
464 #ifdef CONFIG_ROOT_NFS
466 #define NFSROOT_TIMEOUT_MIN 5
467 #define NFSROOT_TIMEOUT_MAX 30
468 #define NFSROOT_RETRY_MAX 5
470 static int __init mount_nfs_root(void)
472 char *root_dev, *root_data;
473 unsigned int timeout;
476 err = nfs_root_data(&root_dev, &root_data);
481 * The server or network may not be ready, so try several
482 * times. Stop after a few tries in case the client wants
483 * to fall back to other boot methods.
485 timeout = NFSROOT_TIMEOUT_MIN;
486 for (try = 1; ; try++) {
487 err = do_mount_root(root_dev, "nfs",
488 root_mountflags, root_data);
491 if (try > NFSROOT_RETRY_MAX)
494 /* Wait, in case the server refused us immediately */
497 if (timeout > NFSROOT_TIMEOUT_MAX)
498 timeout = NFSROOT_TIMEOUT_MAX;
504 #ifdef CONFIG_CIFS_ROOT
506 extern int cifs_root_data(char **dev, char **opts);
508 #define CIFSROOT_TIMEOUT_MIN 5
509 #define CIFSROOT_TIMEOUT_MAX 30
510 #define CIFSROOT_RETRY_MAX 5
512 static int __init mount_cifs_root(void)
514 char *root_dev, *root_data;
515 unsigned int timeout;
518 err = cifs_root_data(&root_dev, &root_data);
522 timeout = CIFSROOT_TIMEOUT_MIN;
523 for (try = 1; ; try++) {
524 err = do_mount_root(root_dev, "cifs", root_mountflags,
528 if (try > CIFSROOT_RETRY_MAX)
533 if (timeout > CIFSROOT_TIMEOUT_MAX)
534 timeout = CIFSROOT_TIMEOUT_MAX;
540 void __init mount_root(void)
542 #ifdef CONFIG_ROOT_NFS
543 if (ROOT_DEV == Root_NFS) {
544 if (!mount_nfs_root())
545 printk(KERN_ERR "VFS: Unable to mount root fs via NFS.\n");
549 #ifdef CONFIG_CIFS_ROOT
550 if (ROOT_DEV == Root_CIFS) {
551 if (!mount_cifs_root())
552 printk(KERN_ERR "VFS: Unable to mount root fs via SMB.\n");
558 int err = create_dev("/dev/root", ROOT_DEV);
561 pr_emerg("Failed to create /dev/root: %d\n", err);
562 mount_block_root("/dev/root", root_mountflags);
568 * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
570 void __init prepare_namespace(void)
573 printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
579 * wait for the known devices to complete their probing
581 * Note: this is a potential source of long boot delays.
582 * For example, it is not atypical to wait 5 seconds here
583 * for the touchpad of a laptop to initialize.
585 wait_for_device_probe();
589 if (saved_root_name[0]) {
590 root_device_name = saved_root_name;
591 if (!strncmp(root_device_name, "mtd", 3) ||
592 !strncmp(root_device_name, "ubi", 3)) {
593 mount_block_root(root_device_name, root_mountflags);
596 ROOT_DEV = name_to_dev_t(root_device_name);
597 if (strncmp(root_device_name, "/dev/", 5) == 0)
598 root_device_name += 5;
604 /* wait for any asynchronous scanning to complete */
605 if ((ROOT_DEV == 0) && root_wait) {
606 printk(KERN_INFO "Waiting for root device %s...\n",
608 while (driver_probe_done() != 0 ||
609 (ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
611 async_synchronize_full();
617 init_mount(".", "/", NULL, MS_MOVE, NULL);
621 static bool is_tmpfs;
622 static int rootfs_init_fs_context(struct fs_context *fc)
624 if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
625 return shmem_init_fs_context(fc);
627 return ramfs_init_fs_context(fc);
630 struct file_system_type rootfs_fs_type = {
632 .init_fs_context = rootfs_init_fs_context,
633 .kill_sb = kill_litter_super,
636 void __init init_rootfs(void)
638 if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
639 (!root_fs_names || strstr(root_fs_names, "tmpfs")))