fs/super.c

   1 /*
   2  *  linux/fs/super.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  *
   6  *  super.c contains code to handle: - mount structures
   7  *                                   - super-block tables
   8  *                                   - filesystem drivers list
   9  *                                   - mount system call
  10  *                                   - umount system call
  11  *                                   - ustat system call
  12  *
  13  * GK 2/5/95  -  Changed to support mounting the root fs via NFS
  14  *
  15  *  Added kerneld support: Jacques Gelinas and Bjorn Ekwall
  16  *  Added change_root: Werner Almesberger & Hans Lermen, Feb '96
  17  *  Added options to /proc/mounts:
  18  *    Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996.
  19  *  Added devfs support: Richard Gooch <rgooch@atnf.csiro.au>, 13-JAN-1998
  20  *  Heavily rewritten for 'one fs - one tree' dcache architecture. AV, Mar 2000
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/slab.h>
  25 #include <linux/init.h>
  26 #include <linux/smp_lock.h>
  27 #include <linux/acct.h>
  28 #include <linux/blkdev.h>
  29 #include <linux/quotaops.h>
  30 #include <linux/namei.h>
  31 #include <linux/buffer_head.h>          /* for fsync_super() */
  32 #include <linux/mount.h>
  33 #include <linux/security.h>
  34 #include <linux/syscalls.h>
  35 #include <linux/vfs.h>
  36 #include <linux/writeback.h>            /* for the emergency remount stuff */
  37 #include <linux/idr.h>
  38 #include <linux/kobject.h>
  39 #include <linux/mutex.h>
  40 #include <asm/uaccess.h>
  41
  42
  43 void get_filesystem(struct file_system_type *fs);
  44 void put_filesystem(struct file_system_type *fs);
  45 struct file_system_type *get_fs_type(const char *name);
  46
  47 LIST_HEAD(super_blocks);
  48 DEFINE_SPINLOCK(sb_lock);
  49
  50 /**
  51  *      alloc_super     -       create new superblock
  52  *
  53  *      Allocates and initializes a new &struct super_block.  alloc_super()
  54  *      returns a pointer new superblock or %NULL if allocation had failed.
  55  */
  56 static struct super_block *alloc_super(void)
  57 {
  58         struct super_block *s = kzalloc(sizeof(struct super_block),  GFP_USER);
  59         static struct super_operations default_op;
  60
  61         if (s) {
  62                 if (security_sb_alloc(s)) {
  63                         kfree(s);
  64                         s = NULL;
  65                         goto out;
  66                 }
  67                 INIT_LIST_HEAD(&s->s_dirty);
  68                 INIT_LIST_HEAD(&s->s_io);
  69                 INIT_LIST_HEAD(&s->s_files);
  70                 INIT_LIST_HEAD(&s->s_instances);
  71                 INIT_HLIST_HEAD(&s->s_anon);
  72                 INIT_LIST_HEAD(&s->s_inodes);
  73                 init_rwsem(&s->s_umount);
  74                 mutex_init(&s->s_lock);
  75                 down_write(&s->s_umount);
  76                 s->s_count = S_BIAS;
  77                 atomic_set(&s->s_active, 1);
  78                 mutex_init(&s->s_vfs_rename_mutex);
  79                 mutex_init(&s->s_dquot.dqio_mutex);
  80                 mutex_init(&s->s_dquot.dqonoff_mutex);
  81                 init_rwsem(&s->s_dquot.dqptr_sem);
  82                 init_waitqueue_head(&s->s_wait_unfrozen);
  83                 s->s_maxbytes = MAX_NON_LFS;
  84                 s->dq_op = sb_dquot_ops;
  85                 s->s_qcop = sb_quotactl_ops;
  86                 s->s_op = &default_op;
  87                 s->s_time_gran = 1000000000;
  88         }
  89 out:
  90         return s;
  91 }
  92
  93 /**
  94  *      destroy_super   -       frees a superblock
  95  *      @s: superblock to free
  96  *
  97  *      Frees a superblock.
  98  */
  99 static inline void destroy_super(struct super_block *s)
 100 {
 101         security_sb_free(s);
 102         kfree(s);
 103 }
 104
 105 /* Superblock refcounting  */
 106
 107 /*
 108  * Drop a superblock's refcount.  Returns non-zero if the superblock was
 109  * destroyed.  The caller must hold sb_lock.
 110  */
 111 int __put_super(struct super_block *sb)
 112 {
 113         int ret = 0;
 114
 115         if (!--sb->s_count) {
 116                 destroy_super(sb);
 117                 ret = 1;
 118         }
 119         return ret;
 120 }
 121
 122 /*
 123  * Drop a superblock's refcount.
 124  * Returns non-zero if the superblock is about to be destroyed and
 125  * at least is already removed from super_blocks list, so if we are
 126  * making a loop through super blocks then we need to restart.
 127  * The caller must hold sb_lock.
 128  */
 129 int __put_super_and_need_restart(struct super_block *sb)
 130 {
 131         /* check for race with generic_shutdown_super() */
 132         if (list_empty(&sb->s_list)) {
 133                 /* super block is removed, need to restart... */
 134                 __put_super(sb);
 135                 return 1;
 136         }
 137         /* can't be the last, since s_list is still in use */
 138         sb->s_count--;
 139         BUG_ON(sb->s_count == 0);
 140         return 0;
 141 }
 142
 143 /**
 144  *      put_super       -       drop a temporary reference to superblock
 145  *      @sb: superblock in question
 146  *
 147  *      Drops a temporary reference, frees superblock if there's no
 148  *      references left.
 149  */
 150 static void put_super(struct super_block *sb)
 151 {
 152         spin_lock(&sb_lock);
 153         __put_super(sb);
 154         spin_unlock(&sb_lock);
 155 }
 156
 157
 158 /**
 159  *      deactivate_super        -       drop an active reference to superblock
 160  *      @s: superblock to deactivate
 161  *
 162  *      Drops an active reference to superblock, acquiring a temprory one if
 163  *      there is no active references left.  In that case we lock superblock,
 164  *      tell fs driver to shut it down and drop the temporary reference we
 165  *      had just acquired.
 166  */
 167 void deactivate_super(struct super_block *s)
 168 {
 169         struct file_system_type *fs = s->s_type;
 170         if (atomic_dec_and_lock(&s->s_active, &sb_lock)) {
 171                 s->s_count -= S_BIAS-1;
 172                 spin_unlock(&sb_lock);
 173                 DQUOT_OFF(s);
 174                 down_write(&s->s_umount);
 175                 fs->kill_sb(s);
 176                 put_filesystem(fs);
 177                 put_super(s);
 178         }
 179 }
 180
 181 EXPORT_SYMBOL(deactivate_super);
 182
 183 /**
 184  *      grab_super - acquire an active reference
 185  *      @s: reference we are trying to make active
 186  *
 187  *      Tries to acquire an active reference.  grab_super() is used when we
 188  *      had just found a superblock in super_blocks or fs_type->fs_supers
 189  *      and want to turn it into a full-blown active reference.  grab_super()
 190  *      is called with sb_lock held and drops it.  Returns 1 in case of
 191  *      success, 0 if we had failed (superblock contents was already dead or
 192  *      dying when grab_super() had been called).
 193  */
 194 static int grab_super(struct super_block *s)
 195 {
 196         s->s_count++;
 197         spin_unlock(&sb_lock);
 198         down_write(&s->s_umount);
 199         if (s->s_root) {
 200                 spin_lock(&sb_lock);
 201                 if (s->s_count > S_BIAS) {
 202                         atomic_inc(&s->s_active);
 203                         s->s_count--;
 204                         spin_unlock(&sb_lock);
 205                         return 1;
 206                 }
 207                 spin_unlock(&sb_lock);
 208         }
 209         up_write(&s->s_umount);
 210         put_super(s);
 211         yield();
 212         return 0;
 213 }
 214
 215 /**
 216  *      generic_shutdown_super  -       common helper for ->kill_sb()
 217  *      @sb: superblock to kill
 218  *
 219  *      generic_shutdown_super() does all fs-independent work on superblock
 220  *      shutdown.  Typical ->kill_sb() should pick all fs-specific objects
 221  *      that need destruction out of superblock, call generic_shutdown_super()
 222  *      and release aforementioned objects.  Note: dentries and inodes _are_
 223  *      taken care of and do not need specific handling.
 224  */
 225 void generic_shutdown_super(struct super_block *sb)
 226 {
 227         struct dentry *root = sb->s_root;
 228         struct super_operations *sop = sb->s_op;
 229
 230         if (root) {
 231                 sb->s_root = NULL;
 232                 shrink_dcache_parent(root);
 233                 shrink_dcache_sb(sb);
 234                 dput(root);
 235                 fsync_super(sb);
 236                 lock_super(sb);
 237                 sb->s_flags &= ~MS_ACTIVE;
 238                 /* bad name - it should be evict_inodes() */
 239                 invalidate_inodes(sb);
 240                 lock_kernel();
 241
 242                 if (sop->write_super && sb->s_dirt)
 243                         sop->write_super(sb);
 244                 if (sop->put_super)
 245                         sop->put_super(sb);
 246
 247                 /* Forget any remaining inodes */
 248                 if (invalidate_inodes(sb)) {
 249                         printk("VFS: Busy inodes after unmount of %s. "
 250                            "Self-destruct in 5 seconds.  Have a nice day...\n",
 251                            sb->s_id);
 252                 }
 253
 254                 unlock_kernel();
 255                 unlock_super(sb);
 256         }
 257         spin_lock(&sb_lock);
 258         /* should be initialized for __put_super_and_need_restart() */
 259         list_del_init(&sb->s_list);
 260         list_del(&sb->s_instances);
 261         spin_unlock(&sb_lock);
 262         up_write(&sb->s_umount);
 263 }
 264
 265 EXPORT_SYMBOL(generic_shutdown_super);
 266
 267 /**
 268  *      sget    -       find or create a superblock
 269  *      @type:  filesystem type superblock should belong to
 270  *      @test:  comparison callback
 271  *      @set:   setup callback
 272  *      @data:  argument to each of them
 273  */
 274 struct super_block *sget(struct file_system_type *type,
 275                         int (*test)(struct super_block *,void *),
 276                         int (*set)(struct super_block *,void *),
 277                         void *data)
 278 {
 279         struct super_block *s = NULL;
 280         struct list_head *p;
 281         int err;
 282
 283 retry:
 284         spin_lock(&sb_lock);
 285         if (test) list_for_each(p, &type->fs_supers) {
 286                 struct super_block *old;
 287                 old = list_entry(p, struct super_block, s_instances);
 288                 if (!test(old, data))
 289                         continue;
 290                 if (!grab_super(old))
 291                         goto retry;
 292                 if (s)
 293                         destroy_super(s);
 294                 return old;
 295         }
 296         if (!s) {
 297                 spin_unlock(&sb_lock);
 298                 s = alloc_super();
 299                 if (!s)
 300                         return ERR_PTR(-ENOMEM);
 301                 goto retry;
 302         }
 303
 304         err = set(s, data);
 305         if (err) {
 306                 spin_unlock(&sb_lock);
 307                 destroy_super(s);
 308                 return ERR_PTR(err);
 309         }
 310         s->s_type = type;
 311         strlcpy(s->s_id, type->name, sizeof(s->s_id));
 312         list_add_tail(&s->s_list, &super_blocks);
 313         list_add(&s->s_instances, &type->fs_supers);
 314         spin_unlock(&sb_lock);
 315         get_filesystem(type);
 316         return s;
 317 }
 318
 319 EXPORT_SYMBOL(sget);
 320
 321 void drop_super(struct super_block *sb)
 322 {
 323         up_read(&sb->s_umount);
 324         put_super(sb);
 325 }
 326
 327 EXPORT_SYMBOL(drop_super);
 328
 329 static inline void write_super(struct super_block *sb)
 330 {
 331         lock_super(sb);
 332         if (sb->s_root && sb->s_dirt)
 333                 if (sb->s_op->write_super)
 334                         sb->s_op->write_super(sb);
 335         unlock_super(sb);
 336 }
 337
 338 /*
 339  * Note: check the dirty flag before waiting, so we don't
 340  * hold up the sync while mounting a device. (The newly
 341  * mounted device won't need syncing.)
 342  */
 343 void sync_supers(void)
 344 {
 345         struct super_block *sb;
 346
 347         spin_lock(&sb_lock);
 348 restart:
 349         list_for_each_entry(sb, &super_blocks, s_list) {
 350                 if (sb->s_dirt) {
 351                         sb->s_count++;
 352                         spin_unlock(&sb_lock);
 353                         down_read(&sb->s_umount);
 354                         write_super(sb);
 355                         up_read(&sb->s_umount);
 356                         spin_lock(&sb_lock);
 357                         if (__put_super_and_need_restart(sb))
 358                                 goto restart;
 359                 }
 360         }
 361         spin_unlock(&sb_lock);
 362 }
 363
 364 /*
 365  * Call the ->sync_fs super_op against all filesytems which are r/w and
 366  * which implement it.
 367  *
 368  * This operation is careful to avoid the livelock which could easily happen
 369  * if two or more filesystems are being continuously dirtied.  s_need_sync_fs
 370  * is used only here.  We set it against all filesystems and then clear it as
 371  * we sync them.  So redirtied filesystems are skipped.
 372  *
 373  * But if process A is currently running sync_filesytems and then process B
 374  * calls sync_filesystems as well, process B will set all the s_need_sync_fs
 375  * flags again, which will cause process A to resync everything.  Fix that with
 376  * a local mutex.
 377  *
 378  * (Fabian) Avoid sync_fs with clean fs & wait mode 0
 379  */
 380 void sync_filesystems(int wait)
 381 {
 382         struct super_block *sb;
 383         static DEFINE_MUTEX(mutex);
 384
 385         mutex_lock(&mutex);             /* Could be down_interruptible */
 386         spin_lock(&sb_lock);
 387         list_for_each_entry(sb, &super_blocks, s_list) {
 388                 if (!sb->s_op->sync_fs)
 389                         continue;
 390                 if (sb->s_flags & MS_RDONLY)
 391                         continue;
 392                 sb->s_need_sync_fs = 1;
 393         }
 394
 395 restart:
 396         list_for_each_entry(sb, &super_blocks, s_list) {
 397                 if (!sb->s_need_sync_fs)
 398                         continue;
 399                 sb->s_need_sync_fs = 0;
 400                 if (sb->s_flags & MS_RDONLY)
 401                         continue;       /* hm.  Was remounted r/o meanwhile */
 402                 sb->s_count++;
 403                 spin_unlock(&sb_lock);
 404                 down_read(&sb->s_umount);
 405                 if (sb->s_root && (wait || sb->s_dirt))
 406                         sb->s_op->sync_fs(sb, wait);
 407                 up_read(&sb->s_umount);
 408                 /* restart only when sb is no longer on the list */
 409                 spin_lock(&sb_lock);
 410                 if (__put_super_and_need_restart(sb))
 411                         goto restart;
 412         }
 413         spin_unlock(&sb_lock);
 414         mutex_unlock(&mutex);
 415 }
 416
 417 /**
 418  *      get_super - get the superblock of a device
 419  *      @bdev: device to get the superblock for
 420  *
 421  *      Scans the superblock list and finds the superblock of the file system
 422  *      mounted on the device given. %NULL is returned if no match is found.
 423  */
 424
 425 struct super_block * get_super(struct block_device *bdev)
 426 {
 427         struct super_block *sb;
 428
 429         if (!bdev)
 430                 return NULL;
 431
 432         spin_lock(&sb_lock);
 433 rescan:
 434         list_for_each_entry(sb, &super_blocks, s_list) {
 435                 if (sb->s_bdev == bdev) {
 436                         sb->s_count++;
 437                         spin_unlock(&sb_lock);
 438                         down_read(&sb->s_umount);
 439                         if (sb->s_root)
 440                                 return sb;
 441                         up_read(&sb->s_umount);
 442                         /* restart only when sb is no longer on the list */
 443                         spin_lock(&sb_lock);
 444                         if (__put_super_and_need_restart(sb))
 445                                 goto rescan;
 446                 }
 447         }
 448         spin_unlock(&sb_lock);
 449         return NULL;
 450 }
 451
 452 EXPORT_SYMBOL(get_super);
 453
 454 struct super_block * user_get_super(dev_t dev)
 455 {
 456         struct super_block *sb;
 457
 458         spin_lock(&sb_lock);
 459 rescan:
 460         list_for_each_entry(sb, &super_blocks, s_list) {
 461                 if (sb->s_dev ==  dev) {
 462                         sb->s_count++;
 463                         spin_unlock(&sb_lock);
 464                         down_read(&sb->s_umount);
 465                         if (sb->s_root)
 466                                 return sb;
 467                         up_read(&sb->s_umount);
 468                         /* restart only when sb is no longer on the list */
 469                         spin_lock(&sb_lock);
 470                         if (__put_super_and_need_restart(sb))
 471                                 goto rescan;
 472                 }
 473         }
 474         spin_unlock(&sb_lock);
 475         return NULL;
 476 }
 477
 478 asmlinkage long sys_ustat(unsigned dev, struct ustat __user * ubuf)
 479 {
 480         struct super_block *s;
 481         struct ustat tmp;
 482         struct kstatfs sbuf;
 483         int err = -EINVAL;
 484
 485         s = user_get_super(new_decode_dev(dev));
 486         if (s == NULL)
 487                 goto out;
 488         err = vfs_statfs(s->s_root, &sbuf);
 489         drop_super(s);
 490         if (err)
 491                 goto out;
 492
 493         memset(&tmp,0,sizeof(struct ustat));
 494         tmp.f_tfree = sbuf.f_bfree;
 495         tmp.f_tinode = sbuf.f_ffree;
 496
 497         err = copy_to_user(ubuf,&tmp,sizeof(struct ustat)) ? -EFAULT : 0;
 498 out:
 499         return err;
 500 }
 501
 502 /**
 503  *      mark_files_ro
 504  *      @sb: superblock in question
 505  *
 506  *      All files are marked read/only.  We don't care about pending
 507  *      delete files so this should be used in 'force' mode only
 508  */
 509
 510 static void mark_files_ro(struct super_block *sb)
 511 {
 512         struct file *f;
 513
 514         file_list_lock();
 515         list_for_each_entry(f, &sb->s_files, f_u.fu_list) {
 516                 if (S_ISREG(f->f_dentry->d_inode->i_mode) && file_count(f))
 517                         f->f_mode &= ~FMODE_WRITE;
 518         }
 519         file_list_unlock();
 520 }
 521
 522 /**
 523  *      do_remount_sb - asks filesystem to change mount options.
 524  *      @sb:    superblock in question
 525  *      @flags: numeric part of options
 526  *      @data:  the rest of options
 527  *      @force: whether or not to force the change
 528  *
 529  *      Alters the mount options of a mounted file system.
 530  */
 531 int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
 532 {
 533         int retval;
 534
 535         if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
 536                 return -EACCES;
 537         if (flags & MS_RDONLY)
 538                 acct_auto_close(sb);
 539         shrink_dcache_sb(sb);
 540         fsync_super(sb);
 541
 542         /* If we are remounting RDONLY and current sb is read/write,
 543            make sure there are no rw files opened */
 544         if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY)) {
 545                 if (force)
 546                         mark_files_ro(sb);
 547                 else if (!fs_may_remount_ro(sb))
 548                         return -EBUSY;
 549         }
 550
 551         if (sb->s_op->remount_fs) {
 552                 lock_super(sb);
 553                 retval = sb->s_op->remount_fs(sb, &flags, data);
 554                 unlock_super(sb);
 555                 if (retval)
 556                         return retval;
 557         }
 558         sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
 559         return 0;
 560 }
 561
 562 static void do_emergency_remount(unsigned long foo)
 563 {
 564         struct super_block *sb;
 565
 566         spin_lock(&sb_lock);
 567         list_for_each_entry(sb, &super_blocks, s_list) {
 568                 sb->s_count++;
 569                 spin_unlock(&sb_lock);
 570                 down_read(&sb->s_umount);
 571                 if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
 572                         /*
 573                          * ->remount_fs needs lock_kernel().
 574                          *
 575                          * What lock protects sb->s_flags??
 576                          */
 577                         lock_kernel();
 578                         do_remount_sb(sb, MS_RDONLY, NULL, 1);
 579                         unlock_kernel();
 580                 }
 581                 drop_super(sb);
 582                 spin_lock(&sb_lock);
 583         }
 584         spin_unlock(&sb_lock);
 585         printk("Emergency Remount complete\n");
 586 }
 587
 588 void emergency_remount(void)
 589 {
 590         pdflush_operation(do_emergency_remount, 0);
 591 }
 592
 593 /*
 594  * Unnamed block devices are dummy devices used by virtual
 595  * filesystems which don't use real block-devices.  -- jrs
 596  */
 597
 598 static struct idr unnamed_dev_idr;
 599 static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
 600
 601 int set_anon_super(struct super_block *s, void *data)
 602 {
 603         int dev;
 604         int error;
 605
 606  retry:
 607         if (idr_pre_get(&unnamed_dev_idr, GFP_ATOMIC) == 0)
 608                 return -ENOMEM;
 609         spin_lock(&unnamed_dev_lock);
 610         error = idr_get_new(&unnamed_dev_idr, NULL, &dev);
 611         spin_unlock(&unnamed_dev_lock);
 612         if (error == -EAGAIN)
 613                 /* We raced and lost with another CPU. */
 614                 goto retry;
 615         else if (error)
 616                 return -EAGAIN;
 617
 618         if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
 619                 spin_lock(&unnamed_dev_lock);
 620                 idr_remove(&unnamed_dev_idr, dev);
 621                 spin_unlock(&unnamed_dev_lock);
 622                 return -EMFILE;
 623         }
 624         s->s_dev = MKDEV(0, dev & MINORMASK);
 625         return 0;
 626 }
 627
 628 EXPORT_SYMBOL(set_anon_super);
 629
 630 void kill_anon_super(struct super_block *sb)
 631 {
 632         int slot = MINOR(sb->s_dev);
 633
 634         generic_shutdown_super(sb);
 635         spin_lock(&unnamed_dev_lock);
 636         idr_remove(&unnamed_dev_idr, slot);
 637         spin_unlock(&unnamed_dev_lock);
 638 }
 639
 640 EXPORT_SYMBOL(kill_anon_super);
 641
 642 void __init unnamed_dev_init(void)
 643 {
 644         idr_init(&unnamed_dev_idr);
 645 }
 646
 647 void kill_litter_super(struct super_block *sb)
 648 {
 649         if (sb->s_root)
 650                 d_genocide(sb->s_root);
 651         kill_anon_super(sb);
 652 }
 653
 654 EXPORT_SYMBOL(kill_litter_super);
 655
 656 static int set_bdev_super(struct super_block *s, void *data)
 657 {
 658         s->s_bdev = data;
 659         s->s_dev = s->s_bdev->bd_dev;
 660         return 0;
 661 }
 662
 663 static int test_bdev_super(struct super_block *s, void *data)
 664 {
 665         return (void *)s->s_bdev == data;
 666 }
 667
 668 static void bdev_uevent(struct block_device *bdev, enum kobject_action action)
 669 {
 670         if (bdev->bd_disk) {
 671                 if (bdev->bd_part)
 672                         kobject_uevent(&bdev->bd_part->kobj, action);
 673                 else
 674                         kobject_uevent(&bdev->bd_disk->kobj, action);
 675         }
 676 }
 677
 678 int get_sb_bdev(struct file_system_type *fs_type,
 679         int flags, const char *dev_name, void *data,
 680         int (*fill_super)(struct super_block *, void *, int),
 681         struct vfsmount *mnt)
 682 {
 683         struct block_device *bdev;
 684         struct super_block *s;
 685         int error = 0;
 686
 687         bdev = open_bdev_excl(dev_name, flags, fs_type);
 688         if (IS_ERR(bdev))
 689                 return PTR_ERR(bdev);
 690
 691         /*
 692          * once the super is inserted into the list by sget, s_umount
 693          * will protect the lockfs code from trying to start a snapshot
 694          * while we are mounting
 695          */
 696         mutex_lock(&bdev->bd_mount_mutex);
 697         s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
 698         mutex_unlock(&bdev->bd_mount_mutex);
 699         if (IS_ERR(s))
 700                 goto error_s;
 701
 702         if (s->s_root) {
 703                 if ((flags ^ s->s_flags) & MS_RDONLY) {
 704                         up_write(&s->s_umount);
 705                         deactivate_super(s);
 706                         error = -EBUSY;
 707                         goto error_bdev;
 708                 }
 709
 710                 close_bdev_excl(bdev);
 711         } else {
 712                 char b[BDEVNAME_SIZE];
 713
 714                 s->s_flags = flags;
 715                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
 716                 sb_set_blocksize(s, block_size(bdev));
 717                 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
 718                 if (error) {
 719                         up_write(&s->s_umount);
 720                         deactivate_super(s);
 721                         goto error;
 722                 }
 723
 724                 s->s_flags |= MS_ACTIVE;
 725                 bdev_uevent(bdev, KOBJ_MOUNT);
 726         }
 727
 728         return simple_set_mnt(mnt, s);
 729
 730 error_s:
 731         error = PTR_ERR(s);
 732 error_bdev:
 733         close_bdev_excl(bdev);
 734 error:
 735         return error;
 736 }
 737
 738 EXPORT_SYMBOL(get_sb_bdev);
 739
 740 void kill_block_super(struct super_block *sb)
 741 {
 742         struct block_device *bdev = sb->s_bdev;
 743
 744         bdev_uevent(bdev, KOBJ_UMOUNT);
 745         generic_shutdown_super(sb);
 746         sync_blockdev(bdev);
 747         close_bdev_excl(bdev);
 748 }
 749
 750 EXPORT_SYMBOL(kill_block_super);
 751
 752 int get_sb_nodev(struct file_system_type *fs_type,
 753         int flags, void *data,
 754         int (*fill_super)(struct super_block *, void *, int),
 755         struct vfsmount *mnt)
 756 {
 757         int error;
 758         struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
 759
 760         if (IS_ERR(s))
 761                 return PTR_ERR(s);
 762
 763         s->s_flags = flags;
 764
 765         error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
 766         if (error) {
 767                 up_write(&s->s_umount);
 768                 deactivate_super(s);
 769                 return error;
 770         }
 771         s->s_flags |= MS_ACTIVE;
 772         return simple_set_mnt(mnt, s);
 773 }
 774
 775 EXPORT_SYMBOL(get_sb_nodev);
 776
 777 static int compare_single(struct super_block *s, void *p)
 778 {
 779         return 1;
 780 }
 781
 782 int get_sb_single(struct file_system_type *fs_type,
 783         int flags, void *data,
 784         int (*fill_super)(struct super_block *, void *, int),
 785         struct vfsmount *mnt)
 786 {
 787         struct super_block *s;
 788         int error;
 789
 790         s = sget(fs_type, compare_single, set_anon_super, NULL);
 791         if (IS_ERR(s))
 792                 return PTR_ERR(s);
 793         if (!s->s_root) {
 794                 s->s_flags = flags;
 795                 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
 796                 if (error) {
 797                         up_write(&s->s_umount);
 798                         deactivate_super(s);
 799                         return error;
 800                 }
 801                 s->s_flags |= MS_ACTIVE;
 802         }
 803         do_remount_sb(s, flags, data, 0);
 804         return simple_set_mnt(mnt, s);
 805 }
 806
 807 EXPORT_SYMBOL(get_sb_single);
 808
 809 struct vfsmount *
 810 vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
 811 {
 812         struct vfsmount *mnt;
 813         char *secdata = NULL;
 814         int error;
 815
 816         if (!type)
 817                 return ERR_PTR(-ENODEV);
 818
 819         error = -ENOMEM;
 820         mnt = alloc_vfsmnt(name);
 821         if (!mnt)
 822                 goto out;
 823
 824         if (data) {
 825                 secdata = alloc_secdata();
 826                 if (!secdata)
 827                         goto out_mnt;
 828
 829                 error = security_sb_copy_data(type, data, secdata);
 830                 if (error)
 831                         goto out_free_secdata;
 832         }
 833
 834         error = type->get_sb(type, flags, name, data, mnt);
 835         if (error < 0)
 836                 goto out_free_secdata;
 837
 838         error = security_sb_kern_mount(mnt->mnt_sb, secdata);
 839         if (error)
 840                 goto out_sb;
 841
 842         mnt->mnt_mountpoint = mnt->mnt_root;
 843         mnt->mnt_parent = mnt;
 844         up_write(&mnt->mnt_sb->s_umount);
 845         free_secdata(secdata);
 846         return mnt;
 847 out_sb:
 848         dput(mnt->mnt_root);
 849         up_write(&mnt->mnt_sb->s_umount);
 850         deactivate_super(mnt->mnt_sb);
 851 out_free_secdata:
 852         free_secdata(secdata);
 853 out_mnt:
 854         free_vfsmnt(mnt);
 855 out:
 856         return ERR_PTR(error);
 857 }
 858
 859 EXPORT_SYMBOL_GPL(vfs_kern_mount);
 860
 861 struct vfsmount *
 862 do_kern_mount(const char *fstype, int flags, const char *name, void *data)
 863 {
 864         struct file_system_type *type = get_fs_type(fstype);
 865         struct vfsmount *mnt;
 866         if (!type)
 867                 return ERR_PTR(-ENODEV);
 868         mnt = vfs_kern_mount(type, flags, name, data);
 869         put_filesystem(type);
 870         return mnt;
 871 }
 872
 873 struct vfsmount *kern_mount(struct file_system_type *type)
 874 {
 875         return vfs_kern_mount(type, 0, type->name, NULL);
 876 }
 877
 878 EXPORT_SYMBOL(kern_mount);