super.c 21.9 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
/*
 *  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:
18
 *    Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996.
L
Linus Torvalds 已提交
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37
 *  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/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/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>
I
Ingo Molnar 已提交
38
#include <linux/mutex.h>
39
#include <linux/file.h>
L
Linus Torvalds 已提交
40
#include <asm/uaccess.h>
41
#include "internal.h"
L
Linus Torvalds 已提交
42 43 44 45 46 47 48


LIST_HEAD(super_blocks);
DEFINE_SPINLOCK(sb_lock);

/**
 *	alloc_super	-	create new superblock
49
 *	@type:	filesystem type superblock should belong to
L
Linus Torvalds 已提交
50 51 52 53
 *
 *	Allocates and initializes a new &struct super_block.  alloc_super()
 *	returns a pointer new superblock or %NULL if allocation had failed.
 */
I
Ingo Molnar 已提交
54
static struct super_block *alloc_super(struct file_system_type *type)
L
Linus Torvalds 已提交
55
{
56
	struct super_block *s = kzalloc(sizeof(struct super_block),  GFP_USER);
L
Linus Torvalds 已提交
57 58 59 60 61 62 63 64 65 66
	static struct super_operations default_op;

	if (s) {
		if (security_sb_alloc(s)) {
			kfree(s);
			s = NULL;
			goto out;
		}
		INIT_LIST_HEAD(&s->s_dirty);
		INIT_LIST_HEAD(&s->s_io);
67
		INIT_LIST_HEAD(&s->s_more_io);
L
Linus Torvalds 已提交
68 69 70 71
		INIT_LIST_HEAD(&s->s_files);
		INIT_LIST_HEAD(&s->s_instances);
		INIT_HLIST_HEAD(&s->s_anon);
		INIT_LIST_HEAD(&s->s_inodes);
72
		INIT_LIST_HEAD(&s->s_dentry_lru);
L
Linus Torvalds 已提交
73
		init_rwsem(&s->s_umount);
74
		mutex_init(&s->s_lock);
75
		lockdep_set_class(&s->s_umount, &type->s_umount_key);
I
Ingo Molnar 已提交
76 77 78 79 80 81
		/*
		 * The locking rules for s_lock are up to the
		 * filesystem. For example ext3fs has different
		 * lock ordering than usbfs:
		 */
		lockdep_set_class(&s->s_lock, &type->s_lock_key);
82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97
		/*
		 * sget() can have s_umount recursion.
		 *
		 * When it cannot find a suitable sb, it allocates a new
		 * one (this one), and tries again to find a suitable old
		 * one.
		 *
		 * In case that succeeds, it will acquire the s_umount
		 * lock of the old one. Since these are clearly distrinct
		 * locks, and this object isn't exposed yet, there's no
		 * risk of deadlocks.
		 *
		 * Annotate this by putting this lock in a different
		 * subclass.
		 */
		down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING);
L
Linus Torvalds 已提交
98 99
		s->s_count = S_BIAS;
		atomic_set(&s->s_active, 1);
100
		mutex_init(&s->s_vfs_rename_mutex);
I
Ingo Molnar 已提交
101 102
		mutex_init(&s->s_dquot.dqio_mutex);
		mutex_init(&s->s_dquot.dqonoff_mutex);
L
Linus Torvalds 已提交
103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123
		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);
M
Miklos Szeredi 已提交
124
	kfree(s->s_subtype);
125
	kfree(s->s_options);
L
Linus Torvalds 已提交
126 127 128 129 130 131 132 133 134
	kfree(s);
}

/* Superblock refcounting  */

/*
 * Drop a superblock's refcount.  Returns non-zero if the superblock was
 * destroyed.  The caller must hold sb_lock.
 */
A
Adrian Bunk 已提交
135
static int __put_super(struct super_block *sb)
L
Linus Torvalds 已提交
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
{
	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);
197
		vfs_dq_off(s, 0);
L
Linus Torvalds 已提交
198 199 200 201 202 203 204 205 206
		down_write(&s->s_umount);
		fs->kill_sb(s);
		put_filesystem(fs);
		put_super(s);
	}
}

EXPORT_SYMBOL(deactivate_super);

A
Al Viro 已提交
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
/**
 *	deactivate_locked_super	-	drop an active reference to superblock
 *	@s: superblock to deactivate
 *
 *	Equivalent of up_write(&s->s_umount); deactivate_super(s);, except that
 *	it does not unlock it until it's all over.  As the result, it's safe to
 *	use to dispose of new superblock on ->get_sb() failure exits - nobody
 *	will see the sucker until it's all over.  Equivalent using up_write +
 *	deactivate_super is safe for that purpose only if superblock is either
 *	safe to use or has NULL ->s_root when we unlock.
 */
void deactivate_locked_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);
		vfs_dq_off(s, 0);
		fs->kill_sb(s);
		put_filesystem(fs);
		put_super(s);
	} else {
		up_write(&s->s_umount);
	}
}

EXPORT_SYMBOL(deactivate_locked_super);

L
Linus Torvalds 已提交
235 236 237 238 239 240 241 242 243 244 245
/**
 *	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).
 */
246
static int grab_super(struct super_block *s) __releases(sb_lock)
L
Linus Torvalds 已提交
247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266
{
	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;
}

267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284
/*
 * Superblock locking.  We really ought to get rid of these two.
 */
void lock_super(struct super_block * sb)
{
	get_fs_excl();
	mutex_lock(&sb->s_lock);
}

void unlock_super(struct super_block * sb)
{
	put_fs_excl();
	mutex_unlock(&sb->s_lock);
}

EXPORT_SYMBOL(lock_super);
EXPORT_SYMBOL(unlock_super);

L
Linus Torvalds 已提交
285 286 287 288 289 290 291 292 293
/**
 *	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.
294 295 296 297
 *
 *	Upon calling this function, the filesystem may no longer alter or
 *	rearrange the set of dentries belonging to this super_block, nor may it
 *	change the attachments of dentries to inodes.
L
Linus Torvalds 已提交
298 299 300
 */
void generic_shutdown_super(struct super_block *sb)
{
301
	const struct super_operations *sop = sb->s_op;
L
Linus Torvalds 已提交
302

303

304 305
	if (sb->s_root) {
		shrink_dcache_for_umount(sb);
306
		sync_filesystem(sb);
307
		get_fs_excl();
L
Linus Torvalds 已提交
308
		sb->s_flags &= ~MS_ACTIVE;
309

L
Linus Torvalds 已提交
310 311 312 313 314 315 316 317
		/* bad name - it should be evict_inodes() */
		invalidate_inodes(sb);

		if (sop->put_super)
			sop->put_super(sb);

		/* Forget any remaining inodes */
		if (invalidate_inodes(sb)) {
318 319 320
			printk("VFS: Busy inodes after unmount of %s. "
			   "Self-destruct in 5 seconds.  Have a nice day...\n",
			   sb->s_id);
L
Linus Torvalds 已提交
321
		}
322
		put_fs_excl();
L
Linus Torvalds 已提交
323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346
	}
	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;
347
	struct super_block *old;
L
Linus Torvalds 已提交
348 349 350 351
	int err;

retry:
	spin_lock(&sb_lock);
352 353 354 355 356 357
	if (test) {
		list_for_each_entry(old, &type->fs_supers, s_instances) {
			if (!test(old, data))
				continue;
			if (!grab_super(old))
				goto retry;
L
Li Zefan 已提交
358 359
			if (s) {
				up_write(&s->s_umount);
360
				destroy_super(s);
L
Li Zefan 已提交
361
			}
362 363
			return old;
		}
L
Linus Torvalds 已提交
364 365 366
	}
	if (!s) {
		spin_unlock(&sb_lock);
I
Ingo Molnar 已提交
367
		s = alloc_super(type);
L
Linus Torvalds 已提交
368 369 370 371 372 373 374 375
		if (!s)
			return ERR_PTR(-ENOMEM);
		goto retry;
	}
		
	err = set(s, data);
	if (err) {
		spin_unlock(&sb_lock);
L
Li Zefan 已提交
376
		up_write(&s->s_umount);
L
Linus Torvalds 已提交
377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398
		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);

C
Christoph Hellwig 已提交
399 400 401 402 403 404 405 406
/**
 * sync_supers - helper for periodic superblock writeback
 *
 * Call the write_super method if present on all dirty superblocks in
 * the system.  This is for the periodic writeback used by most older
 * filesystems.  For data integrity superblock writeback use
 * sync_filesystems() instead.
 *
L
Linus Torvalds 已提交
407 408 409 410 411 412
 * 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)
{
413 414
	struct super_block *sb;

L
Linus Torvalds 已提交
415
	spin_lock(&sb_lock);
416 417
restart:
	list_for_each_entry(sb, &super_blocks, s_list) {
C
Christoph Hellwig 已提交
418
		if (sb->s_op->write_super && sb->s_dirt) {
L
Linus Torvalds 已提交
419 420
			sb->s_count++;
			spin_unlock(&sb_lock);
C
Christoph Hellwig 已提交
421

L
Linus Torvalds 已提交
422
			down_read(&sb->s_umount);
C
Christoph Hellwig 已提交
423 424
			if (sb->s_root && sb->s_dirt)
				sb->s_op->write_super(sb);
425
			up_read(&sb->s_umount);
C
Christoph Hellwig 已提交
426

427 428 429 430 431
			spin_lock(&sb_lock);
			if (__put_super_and_need_restart(sb))
				goto restart;
		}
	}
L
Linus Torvalds 已提交
432 433 434 435 436 437 438 439 440 441 442 443 444
	spin_unlock(&sb_lock);
}

/**
 *	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)
{
445 446
	struct super_block *sb;

L
Linus Torvalds 已提交
447 448
	if (!bdev)
		return NULL;
449

L
Linus Torvalds 已提交
450
	spin_lock(&sb_lock);
451 452 453 454
rescan:
	list_for_each_entry(sb, &super_blocks, s_list) {
		if (sb->s_bdev == bdev) {
			sb->s_count++;
L
Linus Torvalds 已提交
455
			spin_unlock(&sb_lock);
456 457 458 459 460 461 462 463
			down_read(&sb->s_umount);
			if (sb->s_root)
				return sb;
			up_read(&sb->s_umount);
			/* restart only when sb is no longer on the list */
			spin_lock(&sb_lock);
			if (__put_super_and_need_restart(sb))
				goto rescan;
L
Linus Torvalds 已提交
464 465 466 467 468 469 470 471 472 473
		}
	}
	spin_unlock(&sb_lock);
	return NULL;
}

EXPORT_SYMBOL(get_super);
 
struct super_block * user_get_super(dev_t dev)
{
474
	struct super_block *sb;
L
Linus Torvalds 已提交
475 476

	spin_lock(&sb_lock);
477 478 479 480
rescan:
	list_for_each_entry(sb, &super_blocks, s_list) {
		if (sb->s_dev ==  dev) {
			sb->s_count++;
L
Linus Torvalds 已提交
481
			spin_unlock(&sb_lock);
482 483 484 485 486 487 488 489
			down_read(&sb->s_umount);
			if (sb->s_root)
				return sb;
			up_read(&sb->s_umount);
			/* restart only when sb is no longer on the list */
			spin_lock(&sb_lock);
			if (__put_super_and_need_restart(sb))
				goto rescan;
L
Linus Torvalds 已提交
490 491 492 493 494 495
		}
	}
	spin_unlock(&sb_lock);
	return NULL;
}

496
SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf)
L
Linus Torvalds 已提交
497 498 499 500 501 502 503 504 505
{
        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;
506
	err = vfs_statfs(s->s_root, &sbuf);
L
Linus Torvalds 已提交
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
	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;
}

/**
 *	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;
532
	int remount_rw;
L
Linus Torvalds 已提交
533
	
534
#ifdef CONFIG_BLOCK
L
Linus Torvalds 已提交
535 536
	if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
		return -EACCES;
537
#endif
L
Linus Torvalds 已提交
538 539 540
	if (flags & MS_RDONLY)
		acct_auto_close(sb);
	shrink_dcache_sb(sb);
541
	sync_filesystem(sb);
L
Linus Torvalds 已提交
542 543 544 545 546 547

	/* 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);
548
		else if (!fs_may_remount_ro(sb))
L
Linus Torvalds 已提交
549
			return -EBUSY;
550
		retval = vfs_dq_off(sb, 1);
551
		if (retval < 0 && retval != -ENOSYS)
552
			return -EBUSY;
L
Linus Torvalds 已提交
553
	}
554
	remount_rw = !(flags & MS_RDONLY) && (sb->s_flags & MS_RDONLY);
L
Linus Torvalds 已提交
555 556 557

	if (sb->s_op->remount_fs) {
		retval = sb->s_op->remount_fs(sb, &flags, data);
558
		if (retval)
L
Linus Torvalds 已提交
559 560 561
			return retval;
	}
	sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
562
	if (remount_rw)
563
		vfs_dq_quota_on_remount(sb);
L
Linus Torvalds 已提交
564 565 566
	return 0;
}

567
static void do_emergency_remount(struct work_struct *work)
L
Linus Torvalds 已提交
568 569 570 571 572 573 574
{
	struct super_block *sb;

	spin_lock(&sb_lock);
	list_for_each_entry(sb, &super_blocks, s_list) {
		sb->s_count++;
		spin_unlock(&sb_lock);
575
		down_write(&sb->s_umount);
L
Linus Torvalds 已提交
576 577 578 579 580 581 582 583
		if (sb->s_root && sb->s_bdev && !(sb->s_flags & MS_RDONLY)) {
			/*
			 * ->remount_fs needs lock_kernel().
			 *
			 * What lock protects sb->s_flags??
			 */
			do_remount_sb(sb, MS_RDONLY, NULL, 1);
		}
584 585
		up_write(&sb->s_umount);
		put_super(sb);
L
Linus Torvalds 已提交
586 587 588
		spin_lock(&sb_lock);
	}
	spin_unlock(&sb_lock);
589
	kfree(work);
L
Linus Torvalds 已提交
590 591 592 593 594
	printk("Emergency Remount complete\n");
}

void emergency_remount(void)
{
595 596 597 598 599 600 601
	struct work_struct *work;

	work = kmalloc(sizeof(*work), GFP_ATOMIC);
	if (work) {
		INIT_WORK(work, do_emergency_remount);
		schedule_work(work);
	}
L
Linus Torvalds 已提交
602 603 604 605 606 607 608
}

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

609
static DEFINE_IDA(unnamed_dev_ida);
L
Linus Torvalds 已提交
610 611 612 613 614 615 616 617
static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */

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

 retry:
618
	if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0)
L
Linus Torvalds 已提交
619 620
		return -ENOMEM;
	spin_lock(&unnamed_dev_lock);
621
	error = ida_get_new(&unnamed_dev_ida, &dev);
L
Linus Torvalds 已提交
622 623 624 625 626 627 628 629 630
	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);
631
		ida_remove(&unnamed_dev_ida, dev);
L
Linus Torvalds 已提交
632 633 634 635 636 637 638 639 640 641 642 643 644 645 646
		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);
647
	ida_remove(&unnamed_dev_ida, slot);
L
Linus Torvalds 已提交
648 649 650 651 652 653 654 655 656 657 658 659 660 661
	spin_unlock(&unnamed_dev_lock);
}

EXPORT_SYMBOL(kill_anon_super);

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);

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
static int ns_test_super(struct super_block *sb, void *data)
{
	return sb->s_fs_info == data;
}

static int ns_set_super(struct super_block *sb, void *data)
{
	sb->s_fs_info = data;
	return set_anon_super(sb, NULL);
}

int get_sb_ns(struct file_system_type *fs_type, int flags, void *data,
	int (*fill_super)(struct super_block *, void *, int),
	struct vfsmount *mnt)
{
	struct super_block *sb;

	sb = sget(fs_type, ns_test_super, ns_set_super, data);
	if (IS_ERR(sb))
		return PTR_ERR(sb);

	if (!sb->s_root) {
		int err;
		sb->s_flags = flags;
		err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
		if (err) {
A
Al Viro 已提交
688
			deactivate_locked_super(sb);
689 690 691 692 693 694 695 696 697 698 699 700
			return err;
		}

		sb->s_flags |= MS_ACTIVE;
	}

	simple_set_mnt(mnt, sb);
	return 0;
}

EXPORT_SYMBOL(get_sb_ns);

701
#ifdef CONFIG_BLOCK
L
Linus Torvalds 已提交
702 703 704 705 706 707 708 709 710 711 712 713
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;
}

714
int get_sb_bdev(struct file_system_type *fs_type,
L
Linus Torvalds 已提交
715
	int flags, const char *dev_name, void *data,
716 717
	int (*fill_super)(struct super_block *, void *, int),
	struct vfsmount *mnt)
L
Linus Torvalds 已提交
718 719 720
{
	struct block_device *bdev;
	struct super_block *s;
721
	fmode_t mode = FMODE_READ;
L
Linus Torvalds 已提交
722 723
	int error = 0;

724 725 726 727
	if (!(flags & MS_RDONLY))
		mode |= FMODE_WRITE;

	bdev = open_bdev_exclusive(dev_name, mode, fs_type);
L
Linus Torvalds 已提交
728
	if (IS_ERR(bdev))
729
		return PTR_ERR(bdev);
L
Linus Torvalds 已提交
730 731 732 733 734 735

	/*
	 * 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
	 */
736
	down(&bdev->bd_mount_sem);
L
Linus Torvalds 已提交
737
	s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
738
	up(&bdev->bd_mount_sem);
L
Linus Torvalds 已提交
739
	if (IS_ERR(s))
740
		goto error_s;
L
Linus Torvalds 已提交
741 742 743

	if (s->s_root) {
		if ((flags ^ s->s_flags) & MS_RDONLY) {
A
Al Viro 已提交
744
			deactivate_locked_super(s);
745 746
			error = -EBUSY;
			goto error_bdev;
L
Linus Torvalds 已提交
747
		}
748

749
		close_bdev_exclusive(bdev, mode);
L
Linus Torvalds 已提交
750 751 752 753
	} else {
		char b[BDEVNAME_SIZE];

		s->s_flags = flags;
754
		s->s_mode = mode;
L
Linus Torvalds 已提交
755
		strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
756
		sb_set_blocksize(s, block_size(bdev));
757
		error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
L
Linus Torvalds 已提交
758
		if (error) {
A
Al Viro 已提交
759
			deactivate_locked_super(s);
760
			goto error;
761
		}
762 763

		s->s_flags |= MS_ACTIVE;
764
		bdev->bd_super = s;
L
Linus Torvalds 已提交
765 766
	}

767 768
	simple_set_mnt(mnt, s);
	return 0;
L
Linus Torvalds 已提交
769

770 771 772
error_s:
	error = PTR_ERR(s);
error_bdev:
773
	close_bdev_exclusive(bdev, mode);
774 775
error:
	return error;
L
Linus Torvalds 已提交
776 777 778 779 780 781 782
}

EXPORT_SYMBOL(get_sb_bdev);

void kill_block_super(struct super_block *sb)
{
	struct block_device *bdev = sb->s_bdev;
783
	fmode_t mode = sb->s_mode;
L
Linus Torvalds 已提交
784

785
	bdev->bd_super = NULL;
L
Linus Torvalds 已提交
786 787
	generic_shutdown_super(sb);
	sync_blockdev(bdev);
788
	close_bdev_exclusive(bdev, mode);
L
Linus Torvalds 已提交
789 790 791
}

EXPORT_SYMBOL(kill_block_super);
792
#endif
L
Linus Torvalds 已提交
793

794
int get_sb_nodev(struct file_system_type *fs_type,
L
Linus Torvalds 已提交
795
	int flags, void *data,
796 797
	int (*fill_super)(struct super_block *, void *, int),
	struct vfsmount *mnt)
L
Linus Torvalds 已提交
798 799 800 801 802
{
	int error;
	struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);

	if (IS_ERR(s))
803
		return PTR_ERR(s);
L
Linus Torvalds 已提交
804 805 806

	s->s_flags = flags;

807
	error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
L
Linus Torvalds 已提交
808
	if (error) {
A
Al Viro 已提交
809
		deactivate_locked_super(s);
810
		return error;
L
Linus Torvalds 已提交
811 812
	}
	s->s_flags |= MS_ACTIVE;
813 814
	simple_set_mnt(mnt, s);
	return 0;
L
Linus Torvalds 已提交
815 816 817 818 819 820 821 822 823
}

EXPORT_SYMBOL(get_sb_nodev);

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

824
int get_sb_single(struct file_system_type *fs_type,
L
Linus Torvalds 已提交
825
	int flags, void *data,
826 827
	int (*fill_super)(struct super_block *, void *, int),
	struct vfsmount *mnt)
L
Linus Torvalds 已提交
828 829 830 831 832 833
{
	struct super_block *s;
	int error;

	s = sget(fs_type, compare_single, set_anon_super, NULL);
	if (IS_ERR(s))
834
		return PTR_ERR(s);
L
Linus Torvalds 已提交
835 836
	if (!s->s_root) {
		s->s_flags = flags;
837
		error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
L
Linus Torvalds 已提交
838
		if (error) {
A
Al Viro 已提交
839
			deactivate_locked_super(s);
840
			return error;
L
Linus Torvalds 已提交
841 842 843 844
		}
		s->s_flags |= MS_ACTIVE;
	}
	do_remount_sb(s, flags, data, 0);
845 846
	simple_set_mnt(mnt, s);
	return 0;
L
Linus Torvalds 已提交
847 848 849 850 851
}

EXPORT_SYMBOL(get_sb_single);

struct vfsmount *
852
vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
L
Linus Torvalds 已提交
853 854 855
{
	struct vfsmount *mnt;
	char *secdata = NULL;
856
	int error;
L
Linus Torvalds 已提交
857 858 859 860

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

861
	error = -ENOMEM;
L
Linus Torvalds 已提交
862 863 864 865
	mnt = alloc_vfsmnt(name);
	if (!mnt)
		goto out;

866
	if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
L
Linus Torvalds 已提交
867
		secdata = alloc_secdata();
868
		if (!secdata)
L
Linus Torvalds 已提交
869 870
			goto out_mnt;

871
		error = security_sb_copy_data(data, secdata);
872
		if (error)
L
Linus Torvalds 已提交
873 874 875
			goto out_free_secdata;
	}

876 877
	error = type->get_sb(type, flags, name, data, mnt);
	if (error < 0)
L
Linus Torvalds 已提交
878
		goto out_free_secdata;
879
	BUG_ON(!mnt->mnt_sb);
880

881
 	error = security_sb_kern_mount(mnt->mnt_sb, flags, secdata);
L
Linus Torvalds 已提交
882 883
 	if (error)
 		goto out_sb;
884 885

	mnt->mnt_mountpoint = mnt->mnt_root;
L
Linus Torvalds 已提交
886
	mnt->mnt_parent = mnt;
887
	up_write(&mnt->mnt_sb->s_umount);
888
	free_secdata(secdata);
L
Linus Torvalds 已提交
889 890
	return mnt;
out_sb:
891
	dput(mnt->mnt_root);
A
Al Viro 已提交
892
	deactivate_locked_super(mnt->mnt_sb);
L
Linus Torvalds 已提交
893 894 895 896 897
out_free_secdata:
	free_secdata(secdata);
out_mnt:
	free_vfsmnt(mnt);
out:
898
	return ERR_PTR(error);
L
Linus Torvalds 已提交
899 900
}

901 902
EXPORT_SYMBOL_GPL(vfs_kern_mount);

M
Miklos Szeredi 已提交
903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925
static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
{
	int err;
	const char *subtype = strchr(fstype, '.');
	if (subtype) {
		subtype++;
		err = -EINVAL;
		if (!subtype[0])
			goto err;
	} else
		subtype = "";

	mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL);
	err = -ENOMEM;
	if (!mnt->mnt_sb->s_subtype)
		goto err;
	return mnt;

 err:
	mntput(mnt);
	return ERR_PTR(err);
}

926 927 928 929 930 931 932 933
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 vfsmount *mnt;
	if (!type)
		return ERR_PTR(-ENODEV);
	mnt = vfs_kern_mount(type, flags, name, data);
M
Miklos Szeredi 已提交
934 935 936
	if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
	    !mnt->mnt_sb->s_subtype)
		mnt = fs_set_subtype(mnt, fstype);
937 938 939
	put_filesystem(type);
	return mnt;
}
940
EXPORT_SYMBOL_GPL(do_kern_mount);
941

942
struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)
L
Linus Torvalds 已提交
943
{
944
	return vfs_kern_mount(type, MS_KERNMOUNT, type->name, data);
L
Linus Torvalds 已提交
945 946
}

947
EXPORT_SYMBOL_GPL(kern_mount_data);