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 /* zero-pad. init_mount() will make sure it's terminated */
163 strncpy(data_page, data, PAGE_SIZE);
166 ret = init_mount(name, "/root", fs, flags, data_page);
171 s = current->fs->pwd.dentry->d_sb;
174 "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
176 sb_rdonly(s) ? " readonly" : "",
177 MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
185 void __init mount_root_generic(char *name, char *pretty_name, int flags)
187 struct page *page = alloc_page(GFP_KERNEL);
188 char *fs_names = page_address(page);
190 char b[BDEVNAME_SIZE];
193 scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)",
194 MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
196 num_fs = split_fs_names(fs_names, PAGE_SIZE);
198 num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);
200 for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1) {
205 err = do_mount_root(name, p, flags, root_mount_data);
217 * Allow the user to distinguish between failed sys_open
218 * and bad superblock on root device.
219 * and give them a list of the available devices
221 printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
222 pretty_name, b, err);
223 printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
224 printk_all_partitions();
227 num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);
229 pr_err("Can't find any bdev filesystem to be used for mount!\n");
231 pr_err("List of all bdev filesystems:\n");
232 for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
237 panic("VFS: Unable to mount root fs on %s", b);
239 if (!(flags & SB_RDONLY)) {
244 printk("List of all partitions:\n");
245 printk_all_partitions();
246 printk("No filesystem could mount root, tried: ");
247 for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
250 panic("VFS: Unable to mount root fs on \"%s\" or %s", pretty_name, b);
255 #ifdef CONFIG_ROOT_NFS
257 #define NFSROOT_TIMEOUT_MIN 5
258 #define NFSROOT_TIMEOUT_MAX 30
259 #define NFSROOT_RETRY_MAX 5
261 static void __init mount_nfs_root(void)
263 char *root_dev, *root_data;
264 unsigned int timeout;
267 if (nfs_root_data(&root_dev, &root_data))
271 * The server or network may not be ready, so try several
272 * times. Stop after a few tries in case the client wants
273 * to fall back to other boot methods.
275 timeout = NFSROOT_TIMEOUT_MIN;
276 for (try = 1; ; try++) {
277 if (!do_mount_root(root_dev, "nfs", root_mountflags, root_data))
279 if (try > NFSROOT_RETRY_MAX)
282 /* Wait, in case the server refused us immediately */
285 if (timeout > NFSROOT_TIMEOUT_MAX)
286 timeout = NFSROOT_TIMEOUT_MAX;
289 pr_err("VFS: Unable to mount root fs via NFS.\n");
292 static inline void mount_nfs_root(void)
295 #endif /* CONFIG_ROOT_NFS */
297 #ifdef CONFIG_CIFS_ROOT
299 #define CIFSROOT_TIMEOUT_MIN 5
300 #define CIFSROOT_TIMEOUT_MAX 30
301 #define CIFSROOT_RETRY_MAX 5
303 static void __init mount_cifs_root(void)
305 char *root_dev, *root_data;
306 unsigned int timeout;
309 if (cifs_root_data(&root_dev, &root_data))
312 timeout = CIFSROOT_TIMEOUT_MIN;
313 for (try = 1; ; try++) {
314 if (!do_mount_root(root_dev, "cifs", root_mountflags,
317 if (try > CIFSROOT_RETRY_MAX)
322 if (timeout > CIFSROOT_TIMEOUT_MAX)
323 timeout = CIFSROOT_TIMEOUT_MAX;
326 pr_err("VFS: Unable to mount root fs via SMB.\n");
329 static inline void mount_cifs_root(void)
332 #endif /* CONFIG_CIFS_ROOT */
334 static bool __init fs_is_nodev(char *fstype)
336 struct file_system_type *fs = get_fs_type(fstype);
340 ret = !(fs->fs_flags & FS_REQUIRES_DEV);
347 static int __init mount_nodev_root(char *root_device_name)
349 char *fs_names, *fstype;
353 fs_names = (void *)__get_free_page(GFP_KERNEL);
356 num_fs = split_fs_names(fs_names, PAGE_SIZE);
358 for (i = 0, fstype = fs_names; i < num_fs;
359 i++, fstype += strlen(fstype) + 1) {
362 if (!fs_is_nodev(fstype))
364 err = do_mount_root(root_device_name, fstype, root_mountflags,
370 free_page((unsigned long)fs_names);
375 static void __init mount_block_root(char *root_device_name)
377 int err = create_dev("/dev/root", ROOT_DEV);
380 pr_emerg("Failed to create /dev/root: %d\n", err);
381 mount_root_generic("/dev/root", root_device_name, root_mountflags);
384 static inline void mount_block_root(char *root_device_name)
387 #endif /* CONFIG_BLOCK */
389 void __init mount_root(char *root_device_name)
399 mount_root_generic(root_device_name, root_device_name,
403 if (root_device_name && root_fs_names &&
404 mount_nodev_root(root_device_name) == 0)
408 mount_block_root(root_device_name);
413 /* wait for any asynchronous scanning to complete */
414 static void __init wait_for_root(char *root_device_name)
421 pr_info("Waiting for root device %s...\n", root_device_name);
423 end = ktime_add_ms(ktime_get_raw(), root_wait);
425 while (!driver_probe_done() ||
426 early_lookup_bdev(root_device_name, &ROOT_DEV) < 0) {
428 if (root_wait > 0 && ktime_after(ktime_get_raw(), end))
432 async_synchronize_full();
436 static dev_t __init parse_root_device(char *root_device_name)
441 if (!strncmp(root_device_name, "mtd", 3) ||
442 !strncmp(root_device_name, "ubi", 3))
444 if (strcmp(root_device_name, "/dev/nfs") == 0)
446 if (strcmp(root_device_name, "/dev/cifs") == 0)
448 if (strcmp(root_device_name, "/dev/ram") == 0)
451 error = early_lookup_bdev(root_device_name, &dev);
453 if (error == -EINVAL && root_wait) {
454 pr_err("Disabling rootwait; root= is invalid.\n");
463 * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
465 void __init prepare_namespace(void)
468 printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
474 * wait for the known devices to complete their probing
476 * Note: this is a potential source of long boot delays.
477 * For example, it is not atypical to wait 5 seconds here
478 * for the touchpad of a laptop to initialize.
480 wait_for_device_probe();
484 if (saved_root_name[0])
485 ROOT_DEV = parse_root_device(saved_root_name);
487 if (initrd_load(saved_root_name))
491 wait_for_root(saved_root_name);
492 mount_root(saved_root_name);
495 init_mount(".", "/", NULL, MS_MOVE, NULL);
499 static bool is_tmpfs;
500 static int rootfs_init_fs_context(struct fs_context *fc)
502 if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
503 return shmem_init_fs_context(fc);
505 return ramfs_init_fs_context(fc);
508 struct file_system_type rootfs_fs_type = {
510 .init_fs_context = rootfs_init_fs_context,
511 .kill_sb = kill_litter_super,
514 void __init init_rootfs(void)
516 if (IS_ENABLED(CONFIG_TMPFS)) {
517 if (!saved_root_name[0] && !root_fs_names)
519 else if (root_fs_names && !!strstr(root_fs_names, "tmpfs"))