// SPDX-License-Identifier: GPL-2.0-only
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/ctype.h>
#include <linux/fd.h>
#include <linux/tty.h>
#include <linux/suspend.h>
#include <linux/root_dev.h>
#include <linux/security.h>
#include <linux/delay.h>
#include <linux/mount.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/initrd.h>
#include <linux/async.h>
#include <linux/fs_struct.h>
#include <linux/slab.h>
#include <linux/ramfs.h>
#include <linux/shmem_fs.h>
#include <linux/ktime.h>

#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;
        struct page *p = NULL;
        char *data_page = NULL;
        int ret;

        if (data) {
                /* init_mount() requires a full page as fifth argument */
                p = alloc_page(GFP_KERNEL);
                if (!p)
                        return -ENOMEM;
                data_page = page_address(p);
                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:
        if (p)
                put_page(p);
        return ret;
}

void __init mount_root_generic(char *name, char *pretty_name, int flags)
{
        struct page *page = alloc_page(GFP_KERNEL);
        char *fs_names = page_address(page);
        char *p;
        char b[BDEVNAME_SIZE];
        int num_fs, i;

        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:
        put_page(page);
}
 
#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");
}
#else
static 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");
}
#else
static 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 = (void *)__get_free_page(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;
        }

        free_page((unsigned long)fs_names);
        return err;
}

#ifdef CONFIG_BLOCK
static 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);
}
#else
static 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;
        }
}