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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#include <linux/nfs_fs.h>#include <linux/nfs_fs_sb.h>#include <linux/nfs_mount.h>#include <linux/raid/detect.h>#include <uapi/linux/mount.h>
#include "do_mounts.h"
int root_mountflags = MS_RDONLY | MS_SILENT;static char __initdata saved_root_name[64];static int root_wait;
dev_t ROOT_DEV;
static int __init readonly(char *str){ if (*str) return 0; root_mountflags |= MS_RDONLY; return 1;}
static int __init readwrite(char *str){ if (*str) return 0; root_mountflags &= ~MS_RDONLY; return 1;}
__setup("ro", readonly);__setup("rw", readwrite);
static int __init root_dev_setup(char *line){ strscpy(saved_root_name, line, sizeof(saved_root_name)); return 1;}
__setup("root=", root_dev_setup);
static int __init rootwait_setup(char *str){ if (*str) return 0; root_wait = -1; return 1;}
__setup("rootwait", rootwait_setup);
static int __init rootwait_timeout_setup(char *str){ int sec;
if (kstrtoint(str, 0, &sec) || sec < 0) { pr_warn("ignoring invalid rootwait value\n"); goto ignore; }
if (check_mul_overflow(sec, MSEC_PER_SEC, &root_wait)) { pr_warn("ignoring excessive rootwait value\n"); goto ignore; }
return 1;
ignore: /* Fallback to indefinite wait */ root_wait = -1;
return 1;}
__setup("rootwait=", rootwait_timeout_setup);
static char * __initdata root_mount_data;static int __init root_data_setup(char *str){ root_mount_data = str; return 1;}
static char * __initdata root_fs_names;static int __init fs_names_setup(char *str){ root_fs_names = str; return 1;}
static unsigned int __initdata root_delay;static int __init root_delay_setup(char *str){ if (kstrtouint(str, 0, &root_delay)) return 0; return 1;}
__setup("rootflags=", root_data_setup);__setup("rootfstype=", fs_names_setup);__setup("rootdelay=", root_delay_setup);
/* This can return zero length strings. Caller should check */static int __init split_fs_names(char *page, size_t size){ int count = 1; char *p = page;
strscpy(p, root_fs_names, size); while (*p++) { if (p[-1] == ',') { p[-1] = '\0'; count++; } }
return count;}
static int __init do_mount_root(const char *name, const char *fs, const int flags, const void *data){ struct super_block *s; char *data_page = NULL; int ret;
if (data) { /* init_mount() requires a full page as fifth argument */ data_page = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!data_page) return -ENOMEM; strscpy_pad(data_page, data, PAGE_SIZE); }
ret = init_mount(name, "/root", fs, flags, data_page); if (ret) goto out;
init_chdir("/root"); s = current->fs->pwd.dentry->d_sb; ROOT_DEV = s->s_dev; printk(KERN_INFO "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n", s->s_type->name, sb_rdonly(s) ? " readonly" : "", MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
out: kfree(data_page); return ret;}
void __init mount_root_generic(char *name, char *pretty_name, int flags){ char *fs_names = kmalloc(PAGE_SIZE, GFP_KERNEL); char *p; char b[BDEVNAME_SIZE]; int num_fs, i;
if (!fs_names) panic("VFS: Unable to mount root fs: not enough memory");
scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)", MAJOR(ROOT_DEV), MINOR(ROOT_DEV)); if (root_fs_names) num_fs = split_fs_names(fs_names, PAGE_SIZE); else num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE);retry: for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1) { int err;
if (!*p) continue; err = do_mount_root(name, p, flags, root_mount_data); switch (err) { case 0: goto out; case -EACCES: case -EINVAL:#ifdef CONFIG_BLOCK init_flush_fput();#endif continue; } /* * Allow the user to distinguish between failed sys_open * and bad superblock on root device. * and give them a list of the available devices */ printk("VFS: Cannot open root device \"%s\" or %s: error %d\n", pretty_name, b, err); printk("Please append a correct \"root=\" boot option; here are the available partitions:\n"); printk_all_partitions();
if (root_fs_names) num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE); if (!num_fs) pr_err("Can't find any bdev filesystem to be used for mount!\n"); else { pr_err("List of all bdev filesystems:\n"); for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1) pr_err(" %s", p); pr_err("\n"); }
panic("VFS: Unable to mount root fs on %s", b); } if (!(flags & SB_RDONLY)) { flags |= SB_RDONLY; goto retry; }
printk("List of all partitions:\n"); printk_all_partitions(); printk("No filesystem could mount root, tried: "); for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1) printk(" %s", p); printk("\n"); panic("VFS: Unable to mount root fs on \"%s\" or %s", pretty_name, b);out: kfree(fs_names);} #ifdef CONFIG_ROOT_NFS
#define NFSROOT_TIMEOUT_MIN 5#define NFSROOT_TIMEOUT_MAX 30#define NFSROOT_RETRY_MAX 5
static void __init mount_nfs_root(void){ char *root_dev, *root_data; unsigned int timeout; int try;
if (nfs_root_data(&root_dev, &root_data)) goto fail;
/* * The server or network may not be ready, so try several * times. Stop after a few tries in case the client wants * to fall back to other boot methods. */ timeout = NFSROOT_TIMEOUT_MIN; for (try = 1; ; try++) { if (!do_mount_root(root_dev, "nfs", root_mountflags, root_data)) return; if (try > NFSROOT_RETRY_MAX) break;
/* Wait, in case the server refused us immediately */ ssleep(timeout); timeout <<= 1; if (timeout > NFSROOT_TIMEOUT_MAX) timeout = NFSROOT_TIMEOUT_MAX; }fail: pr_err("VFS: Unable to mount root fs via NFS.\n");}#elsestatic inline void mount_nfs_root(void){}#endif /* CONFIG_ROOT_NFS */
#ifdef CONFIG_CIFS_ROOT
#define CIFSROOT_TIMEOUT_MIN 5#define CIFSROOT_TIMEOUT_MAX 30#define CIFSROOT_RETRY_MAX 5
static void __init mount_cifs_root(void){ char *root_dev, *root_data; unsigned int timeout; int try;
if (cifs_root_data(&root_dev, &root_data)) goto fail;
timeout = CIFSROOT_TIMEOUT_MIN; for (try = 1; ; try++) { if (!do_mount_root(root_dev, "cifs", root_mountflags, root_data)) return; if (try > CIFSROOT_RETRY_MAX) break;
ssleep(timeout); timeout <<= 1; if (timeout > CIFSROOT_TIMEOUT_MAX) timeout = CIFSROOT_TIMEOUT_MAX; }fail: pr_err("VFS: Unable to mount root fs via SMB.\n");}#elsestatic inline void mount_cifs_root(void){}#endif /* CONFIG_CIFS_ROOT */
static bool __init fs_is_nodev(char *fstype){ struct file_system_type *fs = get_fs_type(fstype); bool ret = false;
if (fs) { ret = !(fs->fs_flags & FS_REQUIRES_DEV); put_filesystem(fs); }
return ret;}
static int __init mount_nodev_root(char *root_device_name){ char *fs_names, *fstype; int err = -EINVAL; int num_fs, i;
fs_names = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!fs_names) return -EINVAL; num_fs = split_fs_names(fs_names, PAGE_SIZE);
for (i = 0, fstype = fs_names; i < num_fs; i++, fstype += strlen(fstype) + 1) { if (!*fstype) continue; if (!fs_is_nodev(fstype)) continue; err = do_mount_root(root_device_name, fstype, root_mountflags, root_mount_data); if (!err) break; }
kfree(fs_names); return err;}
#ifdef CONFIG_BLOCKstatic void __init mount_block_root(char *root_device_name){ int err = create_dev("/dev/root", ROOT_DEV);
if (err < 0) pr_emerg("Failed to create /dev/root: %d\n", err); mount_root_generic("/dev/root", root_device_name, root_mountflags);}#elsestatic inline void mount_block_root(char *root_device_name){}#endif /* CONFIG_BLOCK */
void __init mount_root(char *root_device_name){ switch (ROOT_DEV) { case Root_NFS: mount_nfs_root(); break; case Root_CIFS: mount_cifs_root(); break; case Root_Generic: mount_root_generic(root_device_name, root_device_name, root_mountflags); break; case 0: if (root_device_name && root_fs_names && mount_nodev_root(root_device_name) == 0) break; fallthrough; default: mount_block_root(root_device_name); break; }}
/* wait for any asynchronous scanning to complete */static void __init wait_for_root(char *root_device_name){ ktime_t end;
if (ROOT_DEV != 0) return;
pr_info("Waiting for root device %s...\n", root_device_name);
end = ktime_add_ms(ktime_get_raw(), root_wait);
while (!driver_probe_done() || early_lookup_bdev(root_device_name, &ROOT_DEV) < 0) { msleep(5); if (root_wait > 0 && ktime_after(ktime_get_raw(), end)) break; }
async_synchronize_full();
}
static dev_t __init parse_root_device(char *root_device_name){ int error; dev_t dev;
if (!strncmp(root_device_name, "mtd", 3) || !strncmp(root_device_name, "ubi", 3)) return Root_Generic; if (strcmp(root_device_name, "/dev/nfs") == 0) return Root_NFS; if (strcmp(root_device_name, "/dev/cifs") == 0) return Root_CIFS; if (strcmp(root_device_name, "/dev/ram") == 0) return Root_RAM0;
error = early_lookup_bdev(root_device_name, &dev); if (error) { if (error == -EINVAL && root_wait) { pr_err("Disabling rootwait; root= is invalid.\n"); root_wait = 0; } return 0; } return dev;}
/* * Prepare the namespace - decide what/where to mount, load ramdisks, etc. */void __init prepare_namespace(void){ if (root_delay) { printk(KERN_INFO "Waiting %d sec before mounting root device...\n", root_delay); ssleep(root_delay); }
/* * wait for the known devices to complete their probing * * Note: this is a potential source of long boot delays. * For example, it is not atypical to wait 5 seconds here * for the touchpad of a laptop to initialize. */ wait_for_device_probe();
md_run_setup();
if (saved_root_name[0]) ROOT_DEV = parse_root_device(saved_root_name);
initrd_load();
if (root_wait) wait_for_root(saved_root_name); mount_root(saved_root_name); devtmpfs_mount();
if (init_pivot_root(".", ".")) { pr_err("VFS: Failed to pivot into new rootfs\n"); return; } if (init_umount(".", MNT_DETACH)) { pr_err("VFS: Failed to unmount old rootfs\n"); return; } pr_info("VFS: Pivoted into new rootfs\n");}
static bool is_tmpfs;static int rootfs_init_fs_context(struct fs_context *fc){ if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs) return shmem_init_fs_context(fc);
return ramfs_init_fs_context(fc);}
struct file_system_type rootfs_fs_type = { .name = "rootfs", .init_fs_context = rootfs_init_fs_context, .kill_sb = kill_anon_super,};
void __init init_rootfs(void){ if (IS_ENABLED(CONFIG_TMPFS)) { if (!saved_root_name[0] && !root_fs_names) is_tmpfs = true; else if (root_fs_names && !!strstr(root_fs_names, "tmpfs")) is_tmpfs = true; }}