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>
21 #include <linux/ktime.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 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);
63 static int __init root_dev_setup(char *line)
65 strscpy(saved_root_name, line, sizeof(saved_root_name));
69 __setup("root=", root_dev_setup);
71 static int __init rootwait_setup(char *str)
79 __setup("rootwait", rootwait_setup);
81 static int __init rootwait_timeout_setup(char *str)
85 if (kstrtoint(str, 0, &sec) || sec < 0) {
86 pr_warn("ignoring invalid rootwait value\n");
90 if (check_mul_overflow(sec, MSEC_PER_SEC, &root_wait)) {
91 pr_warn("ignoring excessive rootwait value\n");
98 /* Fallback to indefinite wait */
104 __setup("rootwait=", rootwait_timeout_setup);
106 static char * __initdata root_mount_data;
107 static int __init root_data_setup(char *str)
109 root_mount_data = str;
113 static char * __initdata root_fs_names;
114 static int __init fs_names_setup(char *str)
120 static unsigned int __initdata root_delay;
121 static int __init root_delay_setup(char *str)
123 root_delay = simple_strtoul(str, NULL, 0);
127 __setup("rootflags=", root_data_setup);
128 __setup("rootfstype=", fs_names_setup);
129 __setup("rootdelay=", root_delay_setup);
131 /* This can return zero length strings. Caller should check */
132 static int __init split_fs_names(char *page, size_t size)
137 strscpy(p, root_fs_names, size);
148 static int __init do_mount_root(const char *name, const char *fs,
149 const int flags, const void *data)
151 struct super_block *s;
152 struct page *p = NULL;
153 char *data_page = NULL;
157 /* init_mount() requires a full page as fifth argument */
158 p = alloc_page(GFP_KERNEL);
161 data_page = page_address(p);
162 strscpy_pad(data_page, data, PAGE_SIZE);
165 ret = init_mount(name, "/root", fs, flags, data_page);
170 s = current->fs->pwd.dentry->d_sb;
173 "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
175 sb_rdonly(s) ? " readonly" : "",
176 MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
184 void __init mount_root_generic(char *name, char *pretty_name, int flags)
186 struct page *page = alloc_page(GFP_KERNEL);
187 char *fs_names = page_address(page);
189 char b[BDEVNAME_SIZE];
192 scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)",
193 MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
195 num_fs = split_fs_names(fs_names, PAGE_SIZE);
197 num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);
199 for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1) {
204 err = do_mount_root(name, p, flags, root_mount_data);
216 * Allow the user to distinguish between failed sys_open
217 * and bad superblock on root device.
218 * and give them a list of the available devices
220 printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
221 pretty_name, b, err);
222 printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
223 printk_all_partitions();
226 num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);
228 pr_err("Can't find any bdev filesystem to be used for mount!\n");
230 pr_err("List of all bdev filesystems:\n");
231 for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
236 panic("VFS: Unable to mount root fs on %s", b);
238 if (!(flags & SB_RDONLY)) {
243 printk("List of all partitions:\n");
244 printk_all_partitions();
245 printk("No filesystem could mount root, tried: ");
246 for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
249 panic("VFS: Unable to mount root fs on \"%s\" or %s", pretty_name, b);
254 #ifdef CONFIG_ROOT_NFS
256 #define NFSROOT_TIMEOUT_MIN 5
257 #define NFSROOT_TIMEOUT_MAX 30
258 #define NFSROOT_RETRY_MAX 5
260 static void __init mount_nfs_root(void)
262 char *root_dev, *root_data;
263 unsigned int timeout;
266 if (nfs_root_data(&root_dev, &root_data))
270 * The server or network may not be ready, so try several
271 * times. Stop after a few tries in case the client wants
272 * to fall back to other boot methods.
274 timeout = NFSROOT_TIMEOUT_MIN;
275 for (try = 1; ; try++) {
276 if (!do_mount_root(root_dev, "nfs", root_mountflags, root_data))
278 if (try > NFSROOT_RETRY_MAX)
281 /* Wait, in case the server refused us immediately */
284 if (timeout > NFSROOT_TIMEOUT_MAX)
285 timeout = NFSROOT_TIMEOUT_MAX;
288 pr_err("VFS: Unable to mount root fs via NFS.\n");
291 static inline void mount_nfs_root(void)
294 #endif /* CONFIG_ROOT_NFS */
296 #ifdef CONFIG_CIFS_ROOT
298 #define CIFSROOT_TIMEOUT_MIN 5
299 #define CIFSROOT_TIMEOUT_MAX 30
300 #define CIFSROOT_RETRY_MAX 5
302 static void __init mount_cifs_root(void)
304 char *root_dev, *root_data;
305 unsigned int timeout;
308 if (cifs_root_data(&root_dev, &root_data))
311 timeout = CIFSROOT_TIMEOUT_MIN;
312 for (try = 1; ; try++) {
313 if (!do_mount_root(root_dev, "cifs", root_mountflags,
316 if (try > CIFSROOT_RETRY_MAX)
321 if (timeout > CIFSROOT_TIMEOUT_MAX)
322 timeout = CIFSROOT_TIMEOUT_MAX;
325 pr_err("VFS: Unable to mount root fs via SMB.\n");
328 static inline void mount_cifs_root(void)
331 #endif /* CONFIG_CIFS_ROOT */
333 static bool __init fs_is_nodev(char *fstype)
335 struct file_system_type *fs = get_fs_type(fstype);
339 ret = !(fs->fs_flags & FS_REQUIRES_DEV);
346 static int __init mount_nodev_root(char *root_device_name)
348 char *fs_names, *fstype;
352 fs_names = (void *)__get_free_page(GFP_KERNEL);
355 num_fs = split_fs_names(fs_names, PAGE_SIZE);
357 for (i = 0, fstype = fs_names; i < num_fs;
358 i++, fstype += strlen(fstype) + 1) {
361 if (!fs_is_nodev(fstype))
363 err = do_mount_root(root_device_name, fstype, root_mountflags,
369 free_page((unsigned long)fs_names);
374 static void __init mount_block_root(char *root_device_name)
376 int err = create_dev("/dev/root", ROOT_DEV);
379 pr_emerg("Failed to create /dev/root: %d\n", err);
380 mount_root_generic("/dev/root", root_device_name, root_mountflags);
383 static inline void mount_block_root(char *root_device_name)
386 #endif /* CONFIG_BLOCK */
388 void __init mount_root(char *root_device_name)
398 mount_root_generic(root_device_name, root_device_name,
402 if (root_device_name && root_fs_names &&
403 mount_nodev_root(root_device_name) == 0)
407 mount_block_root(root_device_name);
412 /* wait for any asynchronous scanning to complete */
413 static void __init wait_for_root(char *root_device_name)
420 pr_info("Waiting for root device %s...\n", root_device_name);
422 end = ktime_add_ms(ktime_get_raw(), root_wait);
424 while (!driver_probe_done() ||
425 early_lookup_bdev(root_device_name, &ROOT_DEV) < 0) {
427 if (root_wait > 0 && ktime_after(ktime_get_raw(), end))
431 async_synchronize_full();
435 static dev_t __init parse_root_device(char *root_device_name)
440 if (!strncmp(root_device_name, "mtd", 3) ||
441 !strncmp(root_device_name, "ubi", 3))
443 if (strcmp(root_device_name, "/dev/nfs") == 0)
445 if (strcmp(root_device_name, "/dev/cifs") == 0)
447 if (strcmp(root_device_name, "/dev/ram") == 0)
450 error = early_lookup_bdev(root_device_name, &dev);
452 if (error == -EINVAL && root_wait) {
453 pr_err("Disabling rootwait; root= is invalid.\n");
462 * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
464 void __init prepare_namespace(void)
467 printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
473 * wait for the known devices to complete their probing
475 * Note: this is a potential source of long boot delays.
476 * For example, it is not atypical to wait 5 seconds here
477 * for the touchpad of a laptop to initialize.
479 wait_for_device_probe();
483 if (saved_root_name[0])
484 ROOT_DEV = parse_root_device(saved_root_name);
486 if (initrd_load(saved_root_name))
490 wait_for_root(saved_root_name);
491 mount_root(saved_root_name);
494 init_mount(".", "/", NULL, MS_MOVE, NULL);
498 static bool is_tmpfs;
499 static int rootfs_init_fs_context(struct fs_context *fc)
501 if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
502 return shmem_init_fs_context(fc);
504 return ramfs_init_fs_context(fc);
507 struct file_system_type rootfs_fs_type = {
509 .init_fs_context = rootfs_init_fs_context,
510 .kill_sb = kill_litter_super,
513 void __init init_rootfs(void)
515 if (IS_ENABLED(CONFIG_TMPFS)) {
516 if (!saved_root_name[0] && !root_fs_names)
518 else if (root_fs_names && !!strstr(root_fs_names, "tmpfs"))