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