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