do_mounts.c

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/*
 * Many of the syscalls used in this file expect some of the arguments
 * to be __user pointers not __kernel pointers.  To limit the sparse
 * noise, turn off sparse checking for this file.
 */
#ifdef __CHECKER__
#undef __CHECKER__
#warning "Sparse checking disabled for this file"
#endif

#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/genhd.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/nfs_fs.h>
#include <linux/nfs_fs_sb.h>
#include <linux/nfs_mount.h>

#include "do_mounts.h"

int __initdata rd_doload;   /* 1 = load RAM disk, 0 = don't load */

int root_mountflags = MS_RDONLY | MS_SILENT;
static char * __initdata root_device_name;
static char __initdata saved_root_name[64];
static int root_wait;

dev_t ROOT_DEV;

static int __init load_ramdisk(char *str)
{
    rd_doload = simple_strtol(str,NULL,0) & 3;
    return 1;
}
__setup("load_ramdisk=", load_ramdisk);

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);

#ifdef CONFIG_BLOCK

static int match_dev_by_uuid(struct device *dev, void *data)
{
    u8 *uuid = data;
    struct hd_struct *part = dev_to_part(dev);

    if (!part->info)
        goto no_match;

    if (memcmp(uuid, part->info->uuid, sizeof(part->info->uuid)))
            goto no_match;

    return 1;
no_match:
    return 0;
}


static dev_t devt_from_partuuid(char *uuid_str)
{
    dev_t res = 0;
    struct device *dev = NULL;
    u8 uuid[16];
    struct gendisk *disk;
    struct hd_struct *part;
    int offset = 0;

    if (strlen(uuid_str) < 36)
        goto done;

    /* Check for optional partition number offset attributes. */
    if (uuid_str[36]) {
        char c = 0;
        /* Explicitly fail on poor PARTUUID syntax. */
        if (sscanf(&uuid_str[36],
               "/PARTNROFF=%d%c", &offset, &c) != 1) {
            printk(KERN_ERR "VFS: PARTUUID= is invalid.\n"
             "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
            if (root_wait)
                printk(KERN_ERR
                     "Disabling rootwait; root= is invalid.\n");
            root_wait = 0;
            goto done;
        }
    }

    /* Pack the requested UUID in the expected format. */
    part_pack_uuid(uuid_str, uuid);

    dev = class_find_device(&block_class, NULL, uuid, &match_dev_by_uuid);
    if (!dev)
        goto done;

    res = dev->devt;

    /* Attempt to find the partition by offset. */
    if (!offset)
        goto no_offset;

    res = 0;
    disk = part_to_disk(dev_to_part(dev));
    part = disk_get_part(disk, dev_to_part(dev)->partno + offset);
    if (part) {
        res = part_devt(part);
        put_device(part_to_dev(part));
    }

no_offset:
    put_device(dev);
done:
    return res;
}
#endif

/*
 *  Convert a name into device number.  We accept the following variants:
 *
 *  1) device number in hexadecimal represents itself
 *  2) /dev/nfs represents Root_NFS (0xff)
 *  3) /dev/<disk_name> represents the device number of disk
 *  4) /dev/<disk_name><decimal> represents the device number
 *         of partition - device number of disk plus the partition number
 *  5) /dev/<disk_name>p<decimal> - same as the above, that form is
 *     used when disk name of partitioned disk ends on a digit.
 *  6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
 *     unique id of a partition if the partition table provides it.
 *  7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
 *     a partition with a known unique id.
 *
 *  If name doesn't have fall into the categories above, we return (0,0).
 *  block_class is used to check if something is a disk name. If the disk
 *  name contains slashes, the device name has them replaced with
 *  bangs.
 */

dev_t name_to_dev_t(char *name)
{
    char s[32];
    char *p;
    dev_t res = 0;
    int part;

#ifdef CONFIG_BLOCK
    if (strncmp(name, "PARTUUID=", 9) == 0) {
        name += 9;
        res = devt_from_partuuid(name);
        if (!res)
            goto fail;
        goto done;
    }
#endif

    if (strncmp(name, "/dev/", 5) != 0) {
        unsigned maj, min;

        if (sscanf(name, "%u:%u", &maj, &min) == 2) {
            res = MKDEV(maj, min);
            if (maj != MAJOR(res) || min != MINOR(res))
                goto fail;
        } else {
            res = new_decode_dev(simple_strtoul(name, &p, 16));
            if (*p)
                goto fail;
        }
        goto done;
    }

    name += 5;
    res = Root_NFS;
    if (strcmp(name, "nfs") == 0)
        goto done;
    res = Root_RAM0;
    if (strcmp(name, "ram") == 0)
        goto done;

    if (strlen(name) > 31)
        goto fail;
    strcpy(s, name);
    for (p = s; *p; p++)
        if (*p == '/')
            *p = '!';
    res = blk_lookup_devt(s, 0);
    if (res)
        goto done;

    /*
     * try non-existent, but valid partition, which may only exist
     * after revalidating the disk, like partitioned md devices
     */
    while (p > s && isdigit(p[-1]))
        p--;
    if (p == s || !*p || *p == '0')
        goto fail;

    /* try disk name without <part number> */
    part = simple_strtoul(p, NULL, 10);
    *p = '\0';
    res = blk_lookup_devt(s, part);
    if (res)
        goto done;

    /* try disk name without p<part number> */
    if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
        goto fail;
    p[-1] = '\0';
    res = blk_lookup_devt(s, part);
    if (res)
        goto done;

fail:
    return 0;
done:
    return res;
}

static int __init root_dev_setup(char *line)
{
    strlcpy(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 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)
{
    root_delay = simple_strtoul(str, NULL, 0);
    return 1;
}

__setup("rootflags=", root_data_setup);
__setup("rootfstype=", fs_names_setup);
__setup("rootdelay=", root_delay_setup);

static void __init get_fs_names(char *page)
{
    char *s = page;

    if (root_fs_names) {
        strcpy(page, root_fs_names);
        while (*s++) {
            if (s[-1] == ',')
                s[-1] = '\0';
        }
    } else {
        int len = get_filesystem_list(page);
        char *p, *next;

        page[len] = '\0';
        for (p = page-1; p; p = next) {
            next = strchr(++p, '\n');
            if (*p++ != '\t')
                continue;
            while ((*s++ = *p++) != '\n')
                ;
            s[-1] = '\0';
        }
    }
    *s = '\0';
}

static int __init do_mount_root(char *name, char *fs, int flags, void *data)
{
    struct super_block *s;
    int err = sys_mount(name, "/root", fs, flags, data);
    if (err)
        return err;

    sys_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,
           s->s_flags & MS_RDONLY ?  " readonly" : "",
           MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
    return 0;
}

void __init mount_block_root(char *name, int flags)
{
    struct page *page = alloc_page(GFP_KERNEL |
                    __GFP_NOTRACK_FALSE_POSITIVE);
    char *fs_names = page_address(page);
    char *p;
#ifdef CONFIG_BLOCK
    char b[BDEVNAME_SIZE];
#else
    const char *b = name;
#endif

    get_fs_names(fs_names);
retry:
    for (p = fs_names; *p; p += strlen(p)+1) {
        int err = do_mount_root(name, p, flags, root_mount_data);
        switch (err) {
            case 0:
                goto out;
            case -EACCES:
                flags |= MS_RDONLY;
                goto retry;
            case -EINVAL:
                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
         */
#ifdef CONFIG_BLOCK
        __bdevname(ROOT_DEV, b);
#endif
        printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
                root_device_name, b, err);
        printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");

        printk_all_partitions();
#ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
        printk("DEBUG_BLOCK_EXT_DEVT is enabled, you need to specify "
               "explicit textual name for \"root=\" boot option.\n");
#endif
        panic("VFS: Unable to mount root fs on %s", b);
    }

    printk("List of all partitions:\n");
    printk_all_partitions();
    printk("No filesystem could mount root, tried: ");
    for (p = fs_names; *p; p += strlen(p)+1)
        printk(" %s", p);
    printk("\n");
#ifdef CONFIG_BLOCK
    __bdevname(ROOT_DEV, b);
#endif
    panic("VFS: Unable to mount root fs on %s", 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 int __init mount_nfs_root(void)
{
    char *root_dev, *root_data;
    unsigned int timeout;
    int try, err;

    err = nfs_root_data(&root_dev, &root_data);
    if (err != 0)
        return 0;

    /*
     * 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++) {
        err = do_mount_root(root_dev, "nfs",
                    root_mountflags, root_data);
        if (err == 0)
            return 1;
        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;
    }
    return 0;
}
#endif

#if defined(CONFIG_BLK_DEV_RAM) || defined(CONFIG_BLK_DEV_FD)
void __init change_floppy(char *fmt, ...)
{
    struct termios termios;
    char buf[80];
    char c;
    int fd;
    va_list args;
    va_start(args, fmt);
    vsprintf(buf, fmt, args);
    va_end(args);
    fd = sys_open("/dev/root", O_RDWR | O_NDELAY, 0);
    if (fd >= 0) {
        sys_ioctl(fd, FDEJECT, 0);
        sys_close(fd);
    }
    printk(KERN_NOTICE "VFS: Insert %s and press ENTER\n", buf);
    fd = sys_open("/dev/console", O_RDWR, 0);
    if (fd >= 0) {
        sys_ioctl(fd, TCGETS, (long)&termios);
        termios.c_lflag &= ~ICANON;
        sys_ioctl(fd, TCSETSF, (long)&termios);
        sys_read(fd, &c, 1);
        termios.c_lflag |= ICANON;
        sys_ioctl(fd, TCSETSF, (long)&termios);
        sys_close(fd);
    }
}
#endif

void __init mount_root(void)
{
#ifdef CONFIG_ROOT_NFS
    if (ROOT_DEV == Root_NFS) {
        if (mount_nfs_root())
            return;

        printk(KERN_ERR "VFS: Unable to mount root fs via NFS, trying floppy.\n");
        ROOT_DEV = Root_FD0;
    }
#endif
#ifdef CONFIG_BLK_DEV_FD
    if (MAJOR(ROOT_DEV) == FLOPPY_MAJOR) {
        /* rd_doload is 2 for a dual initrd/ramload setup */
        if (rd_doload==2) {
            if (rd_load_disk(1)) {
                ROOT_DEV = Root_RAM1;
                root_device_name = NULL;
            }
        } else
            change_floppy("root floppy");
    }
#endif
#ifdef CONFIG_BLOCK
    create_dev("/dev/root", ROOT_DEV);
    mount_block_root("/dev/root", root_mountflags);
#endif
}

/*
 * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
 */
void __init prepare_namespace(void)
{
    int is_floppy;

    if (root_delay) {
        printk(KERN_INFO "Waiting %dsec 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_device_name = saved_root_name;
        if (!strncmp(root_device_name, "mtd", 3) ||
            !strncmp(root_device_name, "ubi", 3)) {
            mount_block_root(root_device_name, root_mountflags);
            goto out;
        }
        ROOT_DEV = name_to_dev_t(root_device_name);
        if (strncmp(root_device_name, "/dev/", 5) == 0)
            root_device_name += 5;
    }

    if (initrd_load())
        goto out;

    /* wait for any asynchronous scanning to complete */
    if ((ROOT_DEV == 0) && root_wait) {
        printk(KERN_INFO "Waiting for root device %s...\n",
            saved_root_name);
        while (driver_probe_done() != 0 ||
            (ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
            msleep(100);
        async_synchronize_full();
    }

    is_floppy = MAJOR(ROOT_DEV) == FLOPPY_MAJOR;

    if (is_floppy && rd_doload && rd_load_disk(0))
        ROOT_DEV = Root_RAM0;

    mount_root();
out:
    devtmpfs_mount("dev");
    sys_mount(".", "/", NULL, MS_MOVE, NULL);
    sys_chroot(".");
}