linux/init/do_mounts.c
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   1/*
   2 * Many of the syscalls used in this file expect some of the arguments
   3 * to be __user pointers not __kernel pointers.  To limit the sparse
   4 * noise, turn off sparse checking for this file.
   5 */
   6#ifdef __CHECKER__
   7#undef __CHECKER__
   8#warning "Sparse checking disabled for this file"
   9#endif
  10
  11#include <linux/module.h>
  12#include <linux/sched.h>
  13#include <linux/ctype.h>
  14#include <linux/fd.h>
  15#include <linux/tty.h>
  16#include <linux/suspend.h>
  17#include <linux/root_dev.h>
  18#include <linux/security.h>
  19#include <linux/delay.h>
  20#include <linux/genhd.h>
  21#include <linux/mount.h>
  22#include <linux/device.h>
  23#include <linux/init.h>
  24#include <linux/fs.h>
  25#include <linux/initrd.h>
  26#include <linux/async.h>
  27#include <linux/fs_struct.h>
  28#include <linux/slab.h>
  29#include <linux/ramfs.h>
  30#include <linux/shmem_fs.h>
  31
  32#include <linux/nfs_fs.h>
  33#include <linux/nfs_fs_sb.h>
  34#include <linux/nfs_mount.h>
  35
  36#include "do_mounts.h"
  37
  38int __initdata rd_doload;       /* 1 = load RAM disk, 0 = don't load */
  39
  40int root_mountflags = MS_RDONLY | MS_SILENT;
  41static char * __initdata root_device_name;
  42static char __initdata saved_root_name[64];
  43static int root_wait;
  44
  45dev_t ROOT_DEV;
  46
  47static int __init load_ramdisk(char *str)
  48{
  49        rd_doload = simple_strtol(str,NULL,0) & 3;
  50        return 1;
  51}
  52__setup("load_ramdisk=", load_ramdisk);
  53
  54static int __init readonly(char *str)
  55{
  56        if (*str)
  57                return 0;
  58        root_mountflags |= MS_RDONLY;
  59        return 1;
  60}
  61
  62static int __init readwrite(char *str)
  63{
  64        if (*str)
  65                return 0;
  66        root_mountflags &= ~MS_RDONLY;
  67        return 1;
  68}
  69
  70__setup("ro", readonly);
  71__setup("rw", readwrite);
  72
  73#ifdef CONFIG_BLOCK
  74struct uuidcmp {
  75        const char *uuid;
  76        int len;
  77};
  78
  79/**
  80 * match_dev_by_uuid - callback for finding a partition using its uuid
  81 * @dev:        device passed in by the caller
  82 * @data:       opaque pointer to the desired struct uuidcmp to match
  83 *
  84 * Returns 1 if the device matches, and 0 otherwise.
  85 */
  86static int match_dev_by_uuid(struct device *dev, const void *data)
  87{
  88        const struct uuidcmp *cmp = data;
  89        struct hd_struct *part = dev_to_part(dev);
  90
  91        if (!part->info)
  92                goto no_match;
  93
  94        if (strncasecmp(cmp->uuid, part->info->uuid, cmp->len))
  95                goto no_match;
  96
  97        return 1;
  98no_match:
  99        return 0;
 100}
 101
 102
 103/**
 104 * devt_from_partuuid - looks up the dev_t of a partition by its UUID
 105 * @uuid:       char array containing ascii UUID
 106 *
 107 * The function will return the first partition which contains a matching
 108 * UUID value in its partition_meta_info struct.  This does not search
 109 * by filesystem UUIDs.
 110 *
 111 * If @uuid is followed by a "/PARTNROFF=%d", then the number will be
 112 * extracted and used as an offset from the partition identified by the UUID.
 113 *
 114 * Returns the matching dev_t on success or 0 on failure.
 115 */
 116static dev_t devt_from_partuuid(const char *uuid_str)
 117{
 118        dev_t res = 0;
 119        struct uuidcmp cmp;
 120        struct device *dev = NULL;
 121        struct gendisk *disk;
 122        struct hd_struct *part;
 123        int offset = 0;
 124        bool clear_root_wait = false;
 125        char *slash;
 126
 127        cmp.uuid = uuid_str;
 128
 129        slash = strchr(uuid_str, '/');
 130        /* Check for optional partition number offset attributes. */
 131        if (slash) {
 132                char c = 0;
 133                /* Explicitly fail on poor PARTUUID syntax. */
 134                if (sscanf(slash + 1,
 135                           "PARTNROFF=%d%c", &offset, &c) != 1) {
 136                        clear_root_wait = true;
 137                        goto done;
 138                }
 139                cmp.len = slash - uuid_str;
 140        } else {
 141                cmp.len = strlen(uuid_str);
 142        }
 143
 144        if (!cmp.len) {
 145                clear_root_wait = true;
 146                goto done;
 147        }
 148
 149        dev = class_find_device(&block_class, NULL, &cmp,
 150                                &match_dev_by_uuid);
 151        if (!dev)
 152                goto done;
 153
 154        res = dev->devt;
 155
 156        /* Attempt to find the partition by offset. */
 157        if (!offset)
 158                goto no_offset;
 159
 160        res = 0;
 161        disk = part_to_disk(dev_to_part(dev));
 162        part = disk_get_part(disk, dev_to_part(dev)->partno + offset);
 163        if (part) {
 164                res = part_devt(part);
 165                put_device(part_to_dev(part));
 166        }
 167
 168no_offset:
 169        put_device(dev);
 170done:
 171        if (clear_root_wait) {
 172                pr_err("VFS: PARTUUID= is invalid.\n"
 173                       "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
 174                if (root_wait)
 175                        pr_err("Disabling rootwait; root= is invalid.\n");
 176                root_wait = 0;
 177        }
 178        return res;
 179}
 180#endif
 181
 182/*
 183 *      Convert a name into device number.  We accept the following variants:
 184 *
 185 *      1) device number in hexadecimal represents itself
 186 *      2) /dev/nfs represents Root_NFS (0xff)
 187 *      3) /dev/<disk_name> represents the device number of disk
 188 *      4) /dev/<disk_name><decimal> represents the device number
 189 *         of partition - device number of disk plus the partition number
 190 *      5) /dev/<disk_name>p<decimal> - same as the above, that form is
 191 *         used when disk name of partitioned disk ends on a digit.
 192 *      6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
 193 *         unique id of a partition if the partition table provides it.
 194 *         The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
 195 *         partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
 196 *         filled hex representation of the 32-bit "NT disk signature", and PP
 197 *         is a zero-filled hex representation of the 1-based partition number.
 198 *      7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
 199 *         a partition with a known unique id.
 200 *
 201 *      If name doesn't have fall into the categories above, we return (0,0).
 202 *      block_class is used to check if something is a disk name. If the disk
 203 *      name contains slashes, the device name has them replaced with
 204 *      bangs.
 205 */
 206
 207dev_t name_to_dev_t(char *name)
 208{
 209        char s[32];
 210        char *p;
 211        dev_t res = 0;
 212        int part;
 213
 214#ifdef CONFIG_BLOCK
 215        if (strncmp(name, "PARTUUID=", 9) == 0) {
 216                name += 9;
 217                res = devt_from_partuuid(name);
 218                if (!res)
 219                        goto fail;
 220                goto done;
 221        }
 222#endif
 223
 224        if (strncmp(name, "/dev/", 5) != 0) {
 225                unsigned maj, min;
 226
 227                if (sscanf(name, "%u:%u", &maj, &min) == 2) {
 228                        res = MKDEV(maj, min);
 229                        if (maj != MAJOR(res) || min != MINOR(res))
 230                                goto fail;
 231                } else {
 232                        res = new_decode_dev(simple_strtoul(name, &p, 16));
 233                        if (*p)
 234                                goto fail;
 235                }
 236                goto done;
 237        }
 238
 239        name += 5;
 240        res = Root_NFS;
 241        if (strcmp(name, "nfs") == 0)
 242                goto done;
 243        res = Root_RAM0;
 244        if (strcmp(name, "ram") == 0)
 245                goto done;
 246
 247        if (strlen(name) > 31)
 248                goto fail;
 249        strcpy(s, name);
 250        for (p = s; *p; p++)
 251                if (*p == '/')
 252                        *p = '!';
 253        res = blk_lookup_devt(s, 0);
 254        if (res)
 255                goto done;
 256
 257        /*
 258         * try non-existent, but valid partition, which may only exist
 259         * after revalidating the disk, like partitioned md devices
 260         */
 261        while (p > s && isdigit(p[-1]))
 262                p--;
 263        if (p == s || !*p || *p == '0')
 264                goto fail;
 265
 266        /* try disk name without <part number> */
 267        part = simple_strtoul(p, NULL, 10);
 268        *p = '\0';
 269        res = blk_lookup_devt(s, part);
 270        if (res)
 271                goto done;
 272
 273        /* try disk name without p<part number> */
 274        if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
 275                goto fail;
 276        p[-1] = '\0';
 277        res = blk_lookup_devt(s, part);
 278        if (res)
 279                goto done;
 280
 281fail:
 282        return 0;
 283done:
 284        return res;
 285}
 286
 287static int __init root_dev_setup(char *line)
 288{
 289        strlcpy(saved_root_name, line, sizeof(saved_root_name));
 290        return 1;
 291}
 292
 293__setup("root=", root_dev_setup);
 294
 295static int __init rootwait_setup(char *str)
 296{
 297        if (*str)
 298                return 0;
 299        root_wait = 1;
 300        return 1;
 301}
 302
 303__setup("rootwait", rootwait_setup);
 304
 305static char * __initdata root_mount_data;
 306static int __init root_data_setup(char *str)
 307{
 308        root_mount_data = str;
 309        return 1;
 310}
 311
 312static char * __initdata root_fs_names;
 313static int __init fs_names_setup(char *str)
 314{
 315        root_fs_names = str;
 316        return 1;
 317}
 318
 319static unsigned int __initdata root_delay;
 320static int __init root_delay_setup(char *str)
 321{
 322        root_delay = simple_strtoul(str, NULL, 0);
 323        return 1;
 324}
 325
 326__setup("rootflags=", root_data_setup);
 327__setup("rootfstype=", fs_names_setup);
 328__setup("rootdelay=", root_delay_setup);
 329
 330static void __init get_fs_names(char *page)
 331{
 332        char *s = page;
 333
 334        if (root_fs_names) {
 335                strcpy(page, root_fs_names);
 336                while (*s++) {
 337                        if (s[-1] == ',')
 338                                s[-1] = '\0';
 339                }
 340        } else {
 341                int len = get_filesystem_list(page);
 342                char *p, *next;
 343
 344                page[len] = '\0';
 345                for (p = page-1; p; p = next) {
 346                        next = strchr(++p, '\n');
 347                        if (*p++ != '\t')
 348                                continue;
 349                        while ((*s++ = *p++) != '\n')
 350                                ;
 351                        s[-1] = '\0';
 352                }
 353        }
 354        *s = '\0';
 355}
 356
 357static int __init do_mount_root(char *name, char *fs, int flags, void *data)
 358{
 359        struct super_block *s;
 360        int err = sys_mount(name, "/root", fs, flags, data);
 361        if (err)
 362                return err;
 363
 364        sys_chdir("/root");
 365        s = current->fs->pwd.dentry->d_sb;
 366        ROOT_DEV = s->s_dev;
 367        printk(KERN_INFO
 368               "VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
 369               s->s_type->name,
 370               s->s_flags & MS_RDONLY ?  " readonly" : "",
 371               MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
 372        return 0;
 373}
 374
 375void __init mount_block_root(char *name, int flags)
 376{
 377        struct page *page = alloc_page(GFP_KERNEL |
 378                                        __GFP_NOTRACK_FALSE_POSITIVE);
 379        char *fs_names = page_address(page);
 380        char *p;
 381#ifdef CONFIG_BLOCK
 382        char b[BDEVNAME_SIZE];
 383#else
 384        const char *b = name;
 385#endif
 386
 387        get_fs_names(fs_names);
 388retry:
 389        for (p = fs_names; *p; p += strlen(p)+1) {
 390                int err = do_mount_root(name, p, flags, root_mount_data);
 391                switch (err) {
 392                        case 0:
 393                                goto out;
 394                        case -EACCES:
 395                                flags |= MS_RDONLY;
 396                                goto retry;
 397                        case -EINVAL:
 398                                continue;
 399                }
 400                /*
 401                 * Allow the user to distinguish between failed sys_open
 402                 * and bad superblock on root device.
 403                 * and give them a list of the available devices
 404                 */
 405#ifdef CONFIG_BLOCK
 406                __bdevname(ROOT_DEV, b);
 407#endif
 408                printk("VFS: Cannot open root device \"%s\" or %s: error %d\n",
 409                                root_device_name, b, err);
 410                printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
 411
 412                printk_all_partitions();
 413#ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
 414                printk("DEBUG_BLOCK_EXT_DEVT is enabled, you need to specify "
 415                       "explicit textual name for \"root=\" boot option.\n");
 416#endif
 417                panic("VFS: Unable to mount root fs on %s", b);
 418        }
 419
 420        printk("List of all partitions:\n");
 421        printk_all_partitions();
 422        printk("No filesystem could mount root, tried: ");
 423        for (p = fs_names; *p; p += strlen(p)+1)
 424                printk(" %s", p);
 425        printk("\n");
 426#ifdef CONFIG_BLOCK
 427        __bdevname(ROOT_DEV, b);
 428#endif
 429        panic("VFS: Unable to mount root fs on %s", b);
 430out:
 431        put_page(page);
 432}
 433 
 434#ifdef CONFIG_ROOT_NFS
 435
 436#define NFSROOT_TIMEOUT_MIN     5
 437#define NFSROOT_TIMEOUT_MAX     30
 438#define NFSROOT_RETRY_MAX       5
 439
 440static int __init mount_nfs_root(void)
 441{
 442        char *root_dev, *root_data;
 443        unsigned int timeout;
 444        int try, err;
 445
 446        err = nfs_root_data(&root_dev, &root_data);
 447        if (err != 0)
 448                return 0;
 449
 450        /*
 451         * The server or network may not be ready, so try several
 452         * times.  Stop after a few tries in case the client wants
 453         * to fall back to other boot methods.
 454         */
 455        timeout = NFSROOT_TIMEOUT_MIN;
 456        for (try = 1; ; try++) {
 457                err = do_mount_root(root_dev, "nfs",
 458                                        root_mountflags, root_data);
 459                if (err == 0)
 460                        return 1;
 461                if (try > NFSROOT_RETRY_MAX)
 462                        break;
 463
 464                /* Wait, in case the server refused us immediately */
 465                ssleep(timeout);
 466                timeout <<= 1;
 467                if (timeout > NFSROOT_TIMEOUT_MAX)
 468                        timeout = NFSROOT_TIMEOUT_MAX;
 469        }
 470        return 0;
 471}
 472#endif
 473
 474#if defined(CONFIG_BLK_DEV_RAM) || defined(CONFIG_BLK_DEV_FD)
 475void __init change_floppy(char *fmt, ...)
 476{
 477        struct termios termios;
 478        char buf[80];
 479        char c;
 480        int fd;
 481        va_list args;
 482        va_start(args, fmt);
 483        vsprintf(buf, fmt, args);
 484        va_end(args);
 485        fd = sys_open("/dev/root", O_RDWR | O_NDELAY, 0);
 486        if (fd >= 0) {
 487                sys_ioctl(fd, FDEJECT, 0);
 488                sys_close(fd);
 489        }
 490        printk(KERN_NOTICE "VFS: Insert %s and press ENTER\n", buf);
 491        fd = sys_open("/dev/console", O_RDWR, 0);
 492        if (fd >= 0) {
 493                sys_ioctl(fd, TCGETS, (long)&termios);
 494                termios.c_lflag &= ~ICANON;
 495                sys_ioctl(fd, TCSETSF, (long)&termios);
 496                sys_read(fd, &c, 1);
 497                termios.c_lflag |= ICANON;
 498                sys_ioctl(fd, TCSETSF, (long)&termios);
 499                sys_close(fd);
 500        }
 501}
 502#endif
 503
 504void __init mount_root(void)
 505{
 506#ifdef CONFIG_ROOT_NFS
 507        if (ROOT_DEV == Root_NFS) {
 508                if (mount_nfs_root())
 509                        return;
 510
 511                printk(KERN_ERR "VFS: Unable to mount root fs via NFS, trying floppy.\n");
 512                ROOT_DEV = Root_FD0;
 513        }
 514#endif
 515#ifdef CONFIG_BLK_DEV_FD
 516        if (MAJOR(ROOT_DEV) == FLOPPY_MAJOR) {
 517                /* rd_doload is 2 for a dual initrd/ramload setup */
 518                if (rd_doload==2) {
 519                        if (rd_load_disk(1)) {
 520                                ROOT_DEV = Root_RAM1;
 521                                root_device_name = NULL;
 522                        }
 523                } else
 524                        change_floppy("root floppy");
 525        }
 526#endif
 527#ifdef CONFIG_BLOCK
 528        create_dev("/dev/root", ROOT_DEV);
 529        mount_block_root("/dev/root", root_mountflags);
 530#endif
 531}
 532
 533/*
 534 * Prepare the namespace - decide what/where to mount, load ramdisks, etc.
 535 */
 536void __init prepare_namespace(void)
 537{
 538        int is_floppy;
 539
 540        if (root_delay) {
 541                printk(KERN_INFO "Waiting %d sec before mounting root device...\n",
 542                       root_delay);
 543                ssleep(root_delay);
 544        }
 545
 546        /*
 547         * wait for the known devices to complete their probing
 548         *
 549         * Note: this is a potential source of long boot delays.
 550         * For example, it is not atypical to wait 5 seconds here
 551         * for the touchpad of a laptop to initialize.
 552         */
 553        wait_for_device_probe();
 554
 555        md_run_setup();
 556
 557        if (saved_root_name[0]) {
 558                root_device_name = saved_root_name;
 559                if (!strncmp(root_device_name, "mtd", 3) ||
 560                    !strncmp(root_device_name, "ubi", 3)) {
 561                        mount_block_root(root_device_name, root_mountflags);
 562                        goto out;
 563                }
 564                ROOT_DEV = name_to_dev_t(root_device_name);
 565                if (strncmp(root_device_name, "/dev/", 5) == 0)
 566                        root_device_name += 5;
 567        }
 568
 569        if (initrd_load())
 570                goto out;
 571
 572        /* wait for any asynchronous scanning to complete */
 573        if ((ROOT_DEV == 0) && root_wait) {
 574                printk(KERN_INFO "Waiting for root device %s...\n",
 575                        saved_root_name);
 576                while (driver_probe_done() != 0 ||
 577                        (ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
 578                        msleep(100);
 579                async_synchronize_full();
 580        }
 581
 582        is_floppy = MAJOR(ROOT_DEV) == FLOPPY_MAJOR;
 583
 584        if (is_floppy && rd_doload && rd_load_disk(0))
 585                ROOT_DEV = Root_RAM0;
 586
 587        mount_root();
 588out:
 589        devtmpfs_mount("dev");
 590        sys_mount(".", "/", NULL, MS_MOVE, NULL);
 591        sys_chroot(".");
 592}
 593
 594static bool is_tmpfs;
 595static struct dentry *rootfs_mount(struct file_system_type *fs_type,
 596        int flags, const char *dev_name, void *data)
 597{
 598        static unsigned long once;
 599        void *fill = ramfs_fill_super;
 600
 601        if (test_and_set_bit(0, &once))
 602                return ERR_PTR(-ENODEV);
 603
 604        if (IS_ENABLED(CONFIG_TMPFS) && is_tmpfs)
 605                fill = shmem_fill_super;
 606
 607        return mount_nodev(fs_type, flags, data, fill);
 608}
 609
 610static struct file_system_type rootfs_fs_type = {
 611        .name           = "rootfs",
 612        .mount          = rootfs_mount,
 613        .kill_sb        = kill_litter_super,
 614};
 615
 616int __init init_rootfs(void)
 617{
 618        int err = register_filesystem(&rootfs_fs_type);
 619
 620        if (err)
 621                return err;
 622
 623        if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] &&
 624                (!root_fs_names || strstr(root_fs_names, "tmpfs"))) {
 625                err = shmem_init();
 626                is_tmpfs = true;
 627        } else {
 628                err = init_ramfs_fs();
 629        }
 630
 631        if (err)
 632                unregister_filesystem(&rootfs_fs_type);
 633
 634        return err;
 635}
 636
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