super.c 19.9 KB
Newer Older
L
Linus Torvalds 已提交
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860
/*
 *  linux/fs/super.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  super.c contains code to handle: - mount structures
 *                                   - super-block tables
 *                                   - filesystem drivers list
 *                                   - mount system call
 *                                   - umount system call
 *                                   - ustat system call
 *
 * GK 2/5/95  -  Changed to support mounting the root fs via NFS
 *
 *  Added kerneld support: Jacques Gelinas and Bjorn Ekwall
 *  Added change_root: Werner Almesberger & Hans Lermen, Feb '96
 *  Added options to /proc/mounts:
 *    Torbjrn Lindh (torbjorn.lindh@gopta.se), April 14, 1996.
 *  Added devfs support: Richard Gooch <rgooch@atnf.csiro.au>, 13-JAN-1998
 *  Heavily rewritten for 'one fs - one tree' dcache architecture. AV, Mar 2000
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/smp_lock.h>
#include <linux/acct.h>
#include <linux/blkdev.h>
#include <linux/quotaops.h>
#include <linux/namei.h>
#include <linux/buffer_head.h>		/* for fsync_super() */
#include <linux/mount.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/vfs.h>
#include <linux/writeback.h>		/* for the emergency remount stuff */
#include <linux/idr.h>
#include <linux/kobject.h>
#include <asm/uaccess.h>


void get_filesystem(struct file_system_type *fs);
void put_filesystem(struct file_system_type *fs);
struct file_system_type *get_fs_type(const char *name);

LIST_HEAD(super_blocks);
DEFINE_SPINLOCK(sb_lock);

/**
 *	alloc_super	-	create new superblock
 *
 *	Allocates and initializes a new &struct super_block.  alloc_super()
 *	returns a pointer new superblock or %NULL if allocation had failed.
 */
static struct super_block *alloc_super(void)
{
	struct super_block *s = kmalloc(sizeof(struct super_block),  GFP_USER);
	static struct super_operations default_op;

	if (s) {
		memset(s, 0, sizeof(struct super_block));
		if (security_sb_alloc(s)) {
			kfree(s);
			s = NULL;
			goto out;
		}
		INIT_LIST_HEAD(&s->s_dirty);
		INIT_LIST_HEAD(&s->s_io);
		INIT_LIST_HEAD(&s->s_files);
		INIT_LIST_HEAD(&s->s_instances);
		INIT_HLIST_HEAD(&s->s_anon);
		INIT_LIST_HEAD(&s->s_inodes);
		init_rwsem(&s->s_umount);
		sema_init(&s->s_lock, 1);
		down_write(&s->s_umount);
		s->s_count = S_BIAS;
		atomic_set(&s->s_active, 1);
		sema_init(&s->s_vfs_rename_sem,1);
		sema_init(&s->s_dquot.dqio_sem, 1);
		sema_init(&s->s_dquot.dqonoff_sem, 1);
		init_rwsem(&s->s_dquot.dqptr_sem);
		init_waitqueue_head(&s->s_wait_unfrozen);
		s->s_maxbytes = MAX_NON_LFS;
		s->dq_op = sb_dquot_ops;
		s->s_qcop = sb_quotactl_ops;
		s->s_op = &default_op;
		s->s_time_gran = 1000000000;
	}
out:
	return s;
}

/**
 *	destroy_super	-	frees a superblock
 *	@s: superblock to free
 *
 *	Frees a superblock.
 */
static inline void destroy_super(struct super_block *s)
{
	security_sb_free(s);
	kfree(s);
}

/* Superblock refcounting  */

/*
 * Drop a superblock's refcount.  Returns non-zero if the superblock was
 * destroyed.  The caller must hold sb_lock.
 */
int __put_super(struct super_block *sb)
{
	int ret = 0;

	if (!--sb->s_count) {
		destroy_super(sb);
		ret = 1;
	}
	return ret;
}

/*
 * Drop a superblock's refcount.
 * Returns non-zero if the superblock is about to be destroyed and
 * at least is already removed from super_blocks list, so if we are
 * making a loop through super blocks then we need to restart.
 * The caller must hold sb_lock.
 */
int __put_super_and_need_restart(struct super_block *sb)
{
	/* check for race with generic_shutdown_super() */
	if (list_empty(&sb->s_list)) {
		/* super block is removed, need to restart... */
		__put_super(sb);
		return 1;
	}
	/* can't be the last, since s_list is still in use */
	sb->s_count--;
	BUG_ON(sb->s_count == 0);
	return 0;
}

/**
 *	put_super	-	drop a temporary reference to superblock
 *	@sb: superblock in question
 *
 *	Drops a temporary reference, frees superblock if there's no
 *	references left.
 */
static void put_super(struct super_block *sb)
{
	spin_lock(&sb_lock);
	__put_super(sb);
	spin_unlock(&sb_lock);
}


/**
 *	deactivate_super	-	drop an active reference to superblock
 *	@s: superblock to deactivate
 *
 *	Drops an active reference to superblock, acquiring a temprory one if
 *	there is no active references left.  In that case we lock superblock,
 *	tell fs driver to shut it down and drop the temporary reference we
 *	had just acquired.
 */
void deactivate_super(struct super_block *s)
{
	struct file_system_type *fs = s->s_type;
	if (atomic_dec_and_lock(&s->s_active, &sb_lock)) {
		s->s_count -= S_BIAS-1;
		spin_unlock(&sb_lock);
		down_write(&s->s_umount);
		fs->kill_sb(s);
		put_filesystem(fs);
		put_super(s);
	}
}

EXPORT_SYMBOL(deactivate_super);

/**
 *	grab_super - acquire an active reference
 *	@s: reference we are trying to make active
 *
 *	Tries to acquire an active reference.  grab_super() is used when we
 * 	had just found a superblock in super_blocks or fs_type->fs_supers
 *	and want to turn it into a full-blown active reference.  grab_super()
 *	is called with sb_lock held and drops it.  Returns 1 in case of
 *	success, 0 if we had failed (superblock contents was already dead or
 *	dying when grab_super() had been called).
 */
static int grab_super(struct super_block *s)
{
	s->s_count++;
	spin_unlock(&sb_lock);
	down_write(&s->s_umount);
	if (s->s_root) {
		spin_lock(&sb_lock);
		if (s->s_count > S_BIAS) {
			atomic_inc(&s->s_active);
			s->s_count--;
			spin_unlock(&sb_lock);
			return 1;
		}
		spin_unlock(&sb_lock);
	}
	up_write(&s->s_umount);
	put_super(s);
	yield();
	return 0;
}

/**
 *	generic_shutdown_super	-	common helper for ->kill_sb()
 *	@sb: superblock to kill
 *
 *	generic_shutdown_super() does all fs-independent work on superblock
 *	shutdown.  Typical ->kill_sb() should pick all fs-specific objects
 *	that need destruction out of superblock, call generic_shutdown_super()
 *	and release aforementioned objects.  Note: dentries and inodes _are_
 *	taken care of and do not need specific handling.
 */
void generic_shutdown_super(struct super_block *sb)
{
	struct dentry *root = sb->s_root;
	struct super_operations *sop = sb->s_op;

	if (root) {
		sb->s_root = NULL;
		shrink_dcache_parent(root);
		shrink_dcache_anon(&sb->s_anon);
		dput(root);
		fsync_super(sb);
		lock_super(sb);
		sb->s_flags &= ~MS_ACTIVE;
		/* bad name - it should be evict_inodes() */
		invalidate_inodes(sb);
		lock_kernel();

		if (sop->write_super && sb->s_dirt)
			sop->write_super(sb);
		if (sop->put_super)
			sop->put_super(sb);

		/* Forget any remaining inodes */
		if (invalidate_inodes(sb)) {
			printk("VFS: Busy inodes after unmount. "
			   "Self-destruct in 5 seconds.  Have a nice day...\n");
		}

		unlock_kernel();
		unlock_super(sb);
	}
	spin_lock(&sb_lock);
	/* should be initialized for __put_super_and_need_restart() */
	list_del_init(&sb->s_list);
	list_del(&sb->s_instances);
	spin_unlock(&sb_lock);
	up_write(&sb->s_umount);
}

EXPORT_SYMBOL(generic_shutdown_super);

/**
 *	sget	-	find or create a superblock
 *	@type:	filesystem type superblock should belong to
 *	@test:	comparison callback
 *	@set:	setup callback
 *	@data:	argument to each of them
 */
struct super_block *sget(struct file_system_type *type,
			int (*test)(struct super_block *,void *),
			int (*set)(struct super_block *,void *),
			void *data)
{
	struct super_block *s = NULL;
	struct list_head *p;
	int err;

retry:
	spin_lock(&sb_lock);
	if (test) list_for_each(p, &type->fs_supers) {
		struct super_block *old;
		old = list_entry(p, struct super_block, s_instances);
		if (!test(old, data))
			continue;
		if (!grab_super(old))
			goto retry;
		if (s)
			destroy_super(s);
		return old;
	}
	if (!s) {
		spin_unlock(&sb_lock);
		s = alloc_super();
		if (!s)
			return ERR_PTR(-ENOMEM);
		goto retry;
	}
		
	err = set(s, data);
	if (err) {
		spin_unlock(&sb_lock);
		destroy_super(s);
		return ERR_PTR(err);
	}
	s->s_type = type;
	strlcpy(s->s_id, type->name, sizeof(s->s_id));
	list_add_tail(&s->s_list, &super_blocks);
	list_add(&s->s_instances, &type->fs_supers);
	spin_unlock(&sb_lock);
	get_filesystem(type);
	return s;
}

EXPORT_SYMBOL(sget);

void drop_super(struct super_block *sb)
{
	up_read(&sb->s_umount);
	put_super(sb);
}

EXPORT_SYMBOL(drop_super);

static inline void write_super(struct super_block *sb)
{
	lock_super(sb);
	if (sb->s_root && sb->s_dirt)
		if (sb->s_op->write_super)
			sb->s_op->write_super(sb);
	unlock_super(sb);
}

/*
 * Note: check the dirty flag before waiting, so we don't
 * hold up the sync while mounting a device. (The newly
 * mounted device won't need syncing.)
 */
void sync_supers(void)
{
	struct super_block * sb;
restart:
	spin_lock(&sb_lock);
	sb = sb_entry(super_blocks.next);
	while (sb != sb_entry(&super_blocks))
		if (sb->s_dirt) {
			sb->s_count++;
			spin_unlock(&sb_lock);
			down_read(&sb->s_umount);
			write_super(sb);
			drop_super(sb);
			goto restart;
		} else
			sb = sb_entry(sb->s_list.next);
	spin_unlock(&sb_lock);
}

/*
 * Call the ->sync_fs super_op against all filesytems which are r/w and
 * which implement it.
 *
 * This operation is careful to avoid the livelock which could easily happen
 * if two or more filesystems are being continuously dirtied.  s_need_sync_fs
 * is used only here.  We set it against all filesystems and then clear it as
 * we sync them.  So redirtied filesystems are skipped.
 *
 * But if process A is currently running sync_filesytems and then process B
 * calls sync_filesystems as well, process B will set all the s_need_sync_fs
 * flags again, which will cause process A to resync everything.  Fix that with
 * a local mutex.
 *
 * (Fabian) Avoid sync_fs with clean fs & wait mode 0
 */
void sync_filesystems(int wait)
{
	struct super_block *sb;
	static DECLARE_MUTEX(mutex);

	down(&mutex);		/* Could be down_interruptible */
	spin_lock(&sb_lock);
	for (sb = sb_entry(super_blocks.next); sb != sb_entry(&super_blocks);
			sb = sb_entry(sb->s_list.next)) {
		if (!sb->s_op->sync_fs)
			continue;
		if (sb->s_flags & MS_RDONLY)
			continue;
		sb->s_need_sync_fs = 1;
	}
	spin_unlock(&sb_lock);

restart:
	spin_lock(&sb_lock);
	for (sb = sb_entry(super_blocks.next); sb != sb_entry(&super_blocks);
			sb = sb_entry(sb->s_list.next)) {
		if (!sb->s_need_sync_fs)
			continue;
		sb->s_need_sync_fs = 0;
		if (sb->s_flags & MS_RDONLY)
			continue;	/* hm.  Was remounted r/o meanwhile */
		sb->s_count++;
		spin_unlock(&sb_lock);
		down_read(&sb->s_umount);
		if (sb->s_root && (wait || sb->s_dirt))
			sb->s_op->sync_fs(sb, wait);
		drop_super(sb);
		goto restart;
	}
	spin_unlock(&sb_lock);
	up(&mutex);
}

/**
 *	get_super - get the superblock of a device
 *	@bdev: device to get the superblock for
 *	
 *	Scans the superblock list and finds the superblock of the file system
 *	mounted on the device given. %NULL is returned if no match is found.
 */

struct super_block * get_super(struct block_device *bdev)
{
	struct list_head *p;
	if (!bdev)
		return NULL;
rescan:
	spin_lock(&sb_lock);
	list_for_each(p, &super_blocks) {
		struct super_block *s = sb_entry(p);
		if (s->s_bdev == bdev) {
			s->s_count++;
			spin_unlock(&sb_lock);
			down_read(&s->s_umount);
			if (s->s_root)
				return s;
			drop_super(s);
			goto rescan;
		}
	}
	spin_unlock(&sb_lock);
	return NULL;
}

EXPORT_SYMBOL(get_super);
 
struct super_block * user_get_super(dev_t dev)
{
	struct list_head *p;

rescan:
	spin_lock(&sb_lock);
	list_for_each(p, &super_blocks) {
		struct super_block *s = sb_entry(p);
		if (s->s_dev ==  dev) {
			s->s_count++;
			spin_unlock(&sb_lock);
			down_read(&s->s_umount);
			if (s->s_root)
				return s;
			drop_super(s);
			goto rescan;
		}
	}
	spin_unlock(&sb_lock);
	return NULL;
}

EXPORT_SYMBOL(user_get_super);

asmlinkage long sys_ustat(unsigned dev, struct ustat __user * ubuf)
{
        struct super_block *s;
        struct ustat tmp;
        struct kstatfs sbuf;
	int err = -EINVAL;

        s = user_get_super(new_decode_dev(dev));
        if (s == NULL)
                goto out;
	err = vfs_statfs(s, &sbuf);
	drop_super(s);
	if (err)
		goto out;

        memset(&tmp,0,sizeof(struct ustat));
        tmp.f_tfree = sbuf.f_bfree;
        tmp.f_tinode = sbuf.f_ffree;

        err = copy_to_user(ubuf,&tmp,sizeof(struct ustat)) ? -EFAULT : 0;
out:
	return err;
}

/**
 *	mark_files_ro
 *	@sb: superblock in question
 *
 *	All files are marked read/only.  We don't care about pending
 *	delete files so this should be used in 'force' mode only
 */

static void mark_files_ro(struct super_block *sb)
{
	struct file *f;

	file_list_lock();
	list_for_each_entry(f, &sb->s_files, f_list) {
		if (S_ISREG(f->f_dentry->d_inode->i_mode) && file_count(f))
			f->f_mode &= ~FMODE_WRITE;
	}
	file_list_unlock();
}

/**
 *	do_remount_sb - asks filesystem to change mount options.
 *	@sb:	superblock in question
 *	@flags:	numeric part of options
 *	@data:	the rest of options
 *      @force: whether or not to force the change
 *
 *	Alters the mount options of a mounted file system.
 */
int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
{
	int retval;
	
	if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
		return -EACCES;
	if (flags & MS_RDONLY)
		acct_auto_close(sb);
	shrink_dcache_sb(sb);
	fsync_super(sb);

	/* If we are remounting RDONLY and current sb is read/write,
	   make sure there are no rw files opened */
	if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY)) {
		if (force)
			mark_files_ro(sb);
		else if (!fs_may_remount_ro(sb))
			return -EBUSY;
	}

	if (sb->s_op->remount_fs) {
		lock_super(sb);
		retval = sb->s_op->remount_fs(sb, &flags, data);
		unlock_super(sb);
		if (retval)
			return retval;
	}
	sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
	return 0;
}

static void do_emergency_remount(unsigned long foo)
{
	struct super_block *sb;

	spin_lock(&sb_lock);
	list_for_each_entry(sb, &super_blocks, s_list) {
		sb->s_count++;
		spin_unlock(&sb_lock);
		down_read(&sb->s_umount);
		if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
			/*
			 * ->remount_fs needs lock_kernel().
			 *
			 * What lock protects sb->s_flags??
			 */
			lock_kernel();
			do_remount_sb(sb, MS_RDONLY, NULL, 1);
			unlock_kernel();
		}
		drop_super(sb);
		spin_lock(&sb_lock);
	}
	spin_unlock(&sb_lock);
	printk("Emergency Remount complete\n");
}

void emergency_remount(void)
{
	pdflush_operation(do_emergency_remount, 0);
}

/*
 * Unnamed block devices are dummy devices used by virtual
 * filesystems which don't use real block-devices.  -- jrs
 */

static struct idr unnamed_dev_idr;
static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */

int set_anon_super(struct super_block *s, void *data)
{
	int dev;
	int error;

 retry:
	if (idr_pre_get(&unnamed_dev_idr, GFP_ATOMIC) == 0)
		return -ENOMEM;
	spin_lock(&unnamed_dev_lock);
	error = idr_get_new(&unnamed_dev_idr, NULL, &dev);
	spin_unlock(&unnamed_dev_lock);
	if (error == -EAGAIN)
		/* We raced and lost with another CPU. */
		goto retry;
	else if (error)
		return -EAGAIN;

	if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
		spin_lock(&unnamed_dev_lock);
		idr_remove(&unnamed_dev_idr, dev);
		spin_unlock(&unnamed_dev_lock);
		return -EMFILE;
	}
	s->s_dev = MKDEV(0, dev & MINORMASK);
	return 0;
}

EXPORT_SYMBOL(set_anon_super);

void kill_anon_super(struct super_block *sb)
{
	int slot = MINOR(sb->s_dev);

	generic_shutdown_super(sb);
	spin_lock(&unnamed_dev_lock);
	idr_remove(&unnamed_dev_idr, slot);
	spin_unlock(&unnamed_dev_lock);
}

EXPORT_SYMBOL(kill_anon_super);

void __init unnamed_dev_init(void)
{
	idr_init(&unnamed_dev_idr);
}

void kill_litter_super(struct super_block *sb)
{
	if (sb->s_root)
		d_genocide(sb->s_root);
	kill_anon_super(sb);
}

EXPORT_SYMBOL(kill_litter_super);

static int set_bdev_super(struct super_block *s, void *data)
{
	s->s_bdev = data;
	s->s_dev = s->s_bdev->bd_dev;
	return 0;
}

static int test_bdev_super(struct super_block *s, void *data)
{
	return (void *)s->s_bdev == data;
}

static void bdev_uevent(struct block_device *bdev, enum kobject_action action)
{
	if (bdev->bd_disk) {
		if (bdev->bd_part)
			kobject_uevent(&bdev->bd_part->kobj, action, NULL);
		else
			kobject_uevent(&bdev->bd_disk->kobj, action, NULL);
	}
}

struct super_block *get_sb_bdev(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data,
	int (*fill_super)(struct super_block *, void *, int))
{
	struct block_device *bdev;
	struct super_block *s;
	int error = 0;

	bdev = open_bdev_excl(dev_name, flags, fs_type);
	if (IS_ERR(bdev))
		return (struct super_block *)bdev;

	/*
	 * once the super is inserted into the list by sget, s_umount
	 * will protect the lockfs code from trying to start a snapshot
	 * while we are mounting
	 */
	down(&bdev->bd_mount_sem);
	s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
	up(&bdev->bd_mount_sem);
	if (IS_ERR(s))
		goto out;

	if (s->s_root) {
		if ((flags ^ s->s_flags) & MS_RDONLY) {
			up_write(&s->s_umount);
			deactivate_super(s);
			s = ERR_PTR(-EBUSY);
		}
		goto out;
	} else {
		char b[BDEVNAME_SIZE];

		s->s_flags = flags;
		strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
		s->s_old_blocksize = block_size(bdev);
		sb_set_blocksize(s, s->s_old_blocksize);
		error = fill_super(s, data, flags & MS_VERBOSE ? 1 : 0);
		if (error) {
			up_write(&s->s_umount);
			deactivate_super(s);
			s = ERR_PTR(error);
		} else {
			s->s_flags |= MS_ACTIVE;
			bdev_uevent(bdev, KOBJ_MOUNT);
		}
	}

	return s;

out:
	close_bdev_excl(bdev);
	return s;
}

EXPORT_SYMBOL(get_sb_bdev);

void kill_block_super(struct super_block *sb)
{
	struct block_device *bdev = sb->s_bdev;

	bdev_uevent(bdev, KOBJ_UMOUNT);
	generic_shutdown_super(sb);
	sync_blockdev(bdev);
	close_bdev_excl(bdev);
}

EXPORT_SYMBOL(kill_block_super);

struct super_block *get_sb_nodev(struct file_system_type *fs_type,
	int flags, void *data,
	int (*fill_super)(struct super_block *, void *, int))
{
	int error;
	struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);

	if (IS_ERR(s))
		return s;

	s->s_flags = flags;

	error = fill_super(s, data, flags & MS_VERBOSE ? 1 : 0);
	if (error) {
		up_write(&s->s_umount);
		deactivate_super(s);
		return ERR_PTR(error);
	}
	s->s_flags |= MS_ACTIVE;
	return s;
}

EXPORT_SYMBOL(get_sb_nodev);

static int compare_single(struct super_block *s, void *p)
{
	return 1;
}

struct super_block *get_sb_single(struct file_system_type *fs_type,
	int flags, void *data,
	int (*fill_super)(struct super_block *, void *, int))
{
	struct super_block *s;
	int error;

	s = sget(fs_type, compare_single, set_anon_super, NULL);
	if (IS_ERR(s))
		return s;
	if (!s->s_root) {
		s->s_flags = flags;
		error = fill_super(s, data, flags & MS_VERBOSE ? 1 : 0);
		if (error) {
			up_write(&s->s_umount);
			deactivate_super(s);
			return ERR_PTR(error);
		}
		s->s_flags |= MS_ACTIVE;
	}
	do_remount_sb(s, flags, data, 0);
	return s;
}

EXPORT_SYMBOL(get_sb_single);

struct vfsmount *
do_kern_mount(const char *fstype, int flags, const char *name, void *data)
{
	struct file_system_type *type = get_fs_type(fstype);
	struct super_block *sb = ERR_PTR(-ENOMEM);
	struct vfsmount *mnt;
	int error;
	char *secdata = NULL;

	if (!type)
		return ERR_PTR(-ENODEV);

	mnt = alloc_vfsmnt(name);
	if (!mnt)
		goto out;

	if (data) {
		secdata = alloc_secdata();
		if (!secdata) {
			sb = ERR_PTR(-ENOMEM);
			goto out_mnt;
		}

		error = security_sb_copy_data(type, data, secdata);
		if (error) {
			sb = ERR_PTR(error);
			goto out_free_secdata;
		}
	}

	sb = type->get_sb(type, flags, name, data);
	if (IS_ERR(sb))
		goto out_free_secdata;
 	error = security_sb_kern_mount(sb, secdata);
 	if (error)
 		goto out_sb;
	mnt->mnt_sb = sb;
	mnt->mnt_root = dget(sb->s_root);
	mnt->mnt_mountpoint = sb->s_root;
	mnt->mnt_parent = mnt;
	mnt->mnt_namespace = current->namespace;
	up_write(&sb->s_umount);
	put_filesystem(type);
	return mnt;
out_sb:
	up_write(&sb->s_umount);
	deactivate_super(sb);
	sb = ERR_PTR(error);
out_free_secdata:
	free_secdata(secdata);
out_mnt:
	free_vfsmnt(mnt);
out:
	put_filesystem(type);
	return (struct vfsmount *)sb;
}

EXPORT_SYMBOL_GPL(do_kern_mount);

struct vfsmount *kern_mount(struct file_system_type *type)
{
	return do_kern_mount(type->name, 0, type->name, NULL);
}

EXPORT_SYMBOL(kern_mount);