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>
22 #include <linux/nfs_fs.h>
23 #include <linux/nfs_fs_sb.h>
24 #include <linux/nfs_mount.h>
25 #include <linux/raid/detect.h>
26 #include <uapi/linux/mount.h>
28 #include "do_mounts.h"
30 int root_mountflags = MS_RDONLY | MS_SILENT;
31 static char __initdata saved_root_name[64];
36 static int __init load_ramdisk(char *str)
38 pr_warn("ignoring the deprecated load_ramdisk= option\n");
41 __setup("load_ramdisk=", load_ramdisk);
43 static int __init readonly(char *str)
47 root_mountflags |= MS_RDONLY;
51 static int __init readwrite(char *str)
55 root_mountflags &= ~MS_RDONLY;
59 __setup("ro", readonly);
60 __setup("rw", readwrite);
62 static int __init root_dev_setup(char *line)
64 strscpy(saved_root_name, line, sizeof(saved_root_name));
68 __setup("root=", root_dev_setup);
70 static int __init rootwait_setup(char *str)
78 __setup("rootwait", rootwait_setup);
80 static char * __initdata root_mount_data;
81 static int __init root_data_setup(char *str)
83 root_mount_data = str;
87 static char * __initdata root_fs_names;
88 static int __init fs_names_setup(char *str)
94 static unsigned int __initdata root_delay;
95 static int __init root_delay_setup(char *str)
97 root_delay = simple_strtoul(str, NULL, 0);
101 __setup("rootflags=", root_data_setup);
102 __setup("rootfstype=", fs_names_setup);
103 __setup("rootdelay=", root_delay_setup);
105 /* This can return zero length strings. Caller should check */
106 static int __init split_fs_names(char *page, size_t size)
111 strscpy(p, root_fs_names, size);
122 static int __init do_mount_root(const char *name, const char *fs,
123 const int flags, const void *data)
125 struct super_block *s;
126 struct page *p = NULL;
127 char *data_page = NULL;
131 /* init_mount() requires a full page as fifth argument */
132 p = alloc_page(GFP_KERNEL);
135 data_page = page_address(p);
136 /* zero-pad. init_mount() will make sure it's terminated */
137 strncpy(data_page, data, PAGE_SIZE);
140 ret = init_mount(name, "/root", fs, flags, data_page);
145 s = current->fs->pwd.dentry->d_sb;
148 "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
150 sb_rdonly(s) ? " readonly" : "",
151 MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
159 void __init mount_root_generic(char *name, char *pretty_name, int flags)
161 struct page *page = alloc_page(GFP_KERNEL);
162 char *fs_names = page_address(page);
164 char b[BDEVNAME_SIZE];
167 scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)",
168 MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
170 num_fs = split_fs_names(fs_names, PAGE_SIZE);
172 num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);
174 for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1) {
179 err = do_mount_root(name, p, flags, root_mount_data);
188 * Allow the user to distinguish between failed sys_open
189 * and bad superblock on root device.
190 * and give them a list of the available devices
192 printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
193 pretty_name, b, err);
194 printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
196 printk_all_partitions();
197 panic("VFS: Unable to mount root fs on %s", b);
199 if (!(flags & SB_RDONLY)) {
204 printk("List of all partitions:\n");
205 printk_all_partitions();
206 printk("No filesystem could mount root, tried: ");
207 for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1)
210 panic("VFS: Unable to mount root fs on %s", b);
215 #ifdef CONFIG_ROOT_NFS
217 #define NFSROOT_TIMEOUT_MIN 5
218 #define NFSROOT_TIMEOUT_MAX 30
219 #define NFSROOT_RETRY_MAX 5
221 static void __init mount_nfs_root(void)
223 char *root_dev, *root_data;
224 unsigned int timeout;
227 if (nfs_root_data(&root_dev, &root_data))
231 * The server or network may not be ready, so try several
232 * times. Stop after a few tries in case the client wants
233 * to fall back to other boot methods.
235 timeout = NFSROOT_TIMEOUT_MIN;
236 for (try = 1; ; try++) {
237 if (!do_mount_root(root_dev, "nfs", root_mountflags, root_data))
239 if (try > NFSROOT_RETRY_MAX)
242 /* Wait, in case the server refused us immediately */
245 if (timeout > NFSROOT_TIMEOUT_MAX)
246 timeout = NFSROOT_TIMEOUT_MAX;
249 pr_err("VFS: Unable to mount root fs via NFS.\n");
252 static inline void mount_nfs_root(void)
255 #endif /* CONFIG_ROOT_NFS */
257 #ifdef CONFIG_CIFS_ROOT
259 extern int cifs_root_data(char **dev, char **opts);
261 #define CIFSROOT_TIMEOUT_MIN 5
262 #define CIFSROOT_TIMEOUT_MAX 30
263 #define CIFSROOT_RETRY_MAX 5
265 static void __init mount_cifs_root(void)
267 char *root_dev, *root_data;
268 unsigned int timeout;
271 if (cifs_root_data(&root_dev, &root_data))
274 timeout = CIFSROOT_TIMEOUT_MIN;
275 for (try = 1; ; try++) {
276 if (!do_mount_root(root_dev, "cifs", root_mountflags,
279 if (try > CIFSROOT_RETRY_MAX)
284 if (timeout > CIFSROOT_TIMEOUT_MAX)
285 timeout = CIFSROOT_TIMEOUT_MAX;
288 pr_err("VFS: Unable to mount root fs via SMB.\n");
291 static inline void mount_cifs_root(void)
294 #endif /* CONFIG_CIFS_ROOT */
296 static bool __init fs_is_nodev(char *fstype)
298 struct file_system_type *fs = get_fs_type(fstype);
302 ret = !(fs->fs_flags & FS_REQUIRES_DEV);
309 static int __init mount_nodev_root(char *root_device_name)
311 char *fs_names, *fstype;
315 fs_names = (void *)__get_free_page(GFP_KERNEL);
318 num_fs = split_fs_names(fs_names, PAGE_SIZE);
320 for (i = 0, fstype = fs_names; i < num_fs;
321 i++, fstype += strlen(fstype) + 1) {
324 if (!fs_is_nodev(fstype))
326 err = do_mount_root(root_device_name, fstype, root_mountflags,
332 free_page((unsigned long)fs_names);
337 static void __init mount_block_root(char *root_device_name)
339 int err = create_dev("/dev/root", ROOT_DEV);
342 pr_emerg("Failed to create /dev/root: %d\n", err);
343 mount_root_generic("/dev/root", root_device_name, root_mountflags);
346 static inline void mount_block_root(char *root_device_name)
349 #endif /* CONFIG_BLOCK */
351 void __init mount_root(char *root_device_name)
361 mount_root_generic(root_device_name, root_device_name,
365 if (root_device_name && root_fs_names &&
366 mount_nodev_root(root_device_name) == 0)
370 mount_block_root(root_device_name);
375 /* wait for any asynchronous scanning to complete */
376 static void __init wait_for_root(char *root_device_name)
381 pr_info("Waiting for root device %s...\n", root_device_name);
383 while (!driver_probe_done() ||
384 early_lookup_bdev(root_device_name, &ROOT_DEV) < 0)
386 async_synchronize_full();
390 static dev_t __init parse_root_device(char *root_device_name)
395 if (!strncmp(root_device_name, "mtd", 3) ||
396 !strncmp(root_device_name, "ubi", 3))
398 if (strcmp(root_device_name, "/dev/nfs") == 0)
400 if (strcmp(root_device_name, "/dev/cifs") == 0)
402 if (strcmp(root_device_name, "/dev/ram") == 0)
405 error = early_lookup_bdev(root_device_name, &dev);
407 if (error == -EINVAL && root_wait) {
408 pr_err("Disabling rootwait; root= is invalid.\n");
417 * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
419 void __init prepare_namespace(void)
422 printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
428 * wait for the known devices to complete their probing
430 * Note: this is a potential source of long boot delays.
431 * For example, it is not atypical to wait 5 seconds here
432 * for the touchpad of a laptop to initialize.
434 wait_for_device_probe();
438 if (saved_root_name[0])
439 ROOT_DEV = parse_root_device(saved_root_name);
441 if (initrd_load(saved_root_name))
445 wait_for_root(saved_root_name);
446 mount_root(saved_root_name);
449 init_mount(".", "/", NULL, MS_MOVE, NULL);
453 static bool is_tmpfs;
454 static int rootfs_init_fs_context(struct fs_context *fc)
456 if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
457 return shmem_init_fs_context(fc);
459 return ramfs_init_fs_context(fc);
462 struct file_system_type rootfs_fs_type = {
464 .init_fs_context = rootfs_init_fs_context,
465 .kill_sb = kill_litter_super,
468 void __init init_rootfs(void)
470 if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
471 (!root_fs_names || strstr(root_fs_names, "tmpfs")))