block_dev.c 31.9 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3 4 5 6 7 8 9 10 11 12 13 14
/*
 *  linux/fs/block_dev.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 2001  Andrea Arcangeli <andrea@suse.de> SuSE
 */

#include <linux/init.h>
#include <linux/mm.h>
#include <linux/fcntl.h>
#include <linux/slab.h>
#include <linux/kmod.h>
#include <linux/major.h>
#include <linux/smp_lock.h>
15
#include <linux/device_cgroup.h>
Linus Torvalds's avatar
Linus Torvalds committed
16 17 18 19 20
#include <linux/highmem.h>
#include <linux/blkdev.h>
#include <linux/module.h>
#include <linux/blkpg.h>
#include <linux/buffer_head.h>
21
#include <linux/writeback.h>
Linus Torvalds's avatar
Linus Torvalds committed
22 23 24 25
#include <linux/mpage.h>
#include <linux/mount.h>
#include <linux/uio.h>
#include <linux/namei.h>
26
#include <linux/log2.h>
Linus Torvalds's avatar
Linus Torvalds committed
27
#include <asm/uaccess.h>
28
#include "internal.h"
Linus Torvalds's avatar
Linus Torvalds committed
29 30 31 32 33 34

struct bdev_inode {
	struct block_device bdev;
	struct inode vfs_inode;
};

35 36
static const struct address_space_operations def_blk_aops;

Linus Torvalds's avatar
Linus Torvalds committed
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
static inline struct bdev_inode *BDEV_I(struct inode *inode)
{
	return container_of(inode, struct bdev_inode, vfs_inode);
}

inline struct block_device *I_BDEV(struct inode *inode)
{
	return &BDEV_I(inode)->bdev;
}

EXPORT_SYMBOL(I_BDEV);

static sector_t max_block(struct block_device *bdev)
{
	sector_t retval = ~((sector_t)0);
	loff_t sz = i_size_read(bdev->bd_inode);

	if (sz) {
		unsigned int size = block_size(bdev);
		unsigned int sizebits = blksize_bits(size);
		retval = (sz >> sizebits);
	}
	return retval;
}

62
/* Kill _all_ buffers and pagecache , dirty or not.. */
Linus Torvalds's avatar
Linus Torvalds committed
63 64
static void kill_bdev(struct block_device *bdev)
{
65 66 67
	if (bdev->bd_inode->i_mapping->nrpages == 0)
		return;
	invalidate_bh_lrus();
Linus Torvalds's avatar
Linus Torvalds committed
68 69 70 71 72 73
	truncate_inode_pages(bdev->bd_inode->i_mapping, 0);
}	

int set_blocksize(struct block_device *bdev, int size)
{
	/* Size must be a power of two, and between 512 and PAGE_SIZE */
74
	if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
Linus Torvalds's avatar
Linus Torvalds committed
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
		return -EINVAL;

	/* Size cannot be smaller than the size supported by the device */
	if (size < bdev_hardsect_size(bdev))
		return -EINVAL;

	/* Don't change the size if it is same as current */
	if (bdev->bd_block_size != size) {
		sync_blockdev(bdev);
		bdev->bd_block_size = size;
		bdev->bd_inode->i_blkbits = blksize_bits(size);
		kill_bdev(bdev);
	}
	return 0;
}

EXPORT_SYMBOL(set_blocksize);

int sb_set_blocksize(struct super_block *sb, int size)
{
	if (set_blocksize(sb->s_bdev, size))
		return 0;
	/* If we get here, we know size is power of two
	 * and it's value is between 512 and PAGE_SIZE */
	sb->s_blocksize = size;
100
	sb->s_blocksize_bits = blksize_bits(size);
Linus Torvalds's avatar
Linus Torvalds committed
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
	return sb->s_blocksize;
}

EXPORT_SYMBOL(sb_set_blocksize);

int sb_min_blocksize(struct super_block *sb, int size)
{
	int minsize = bdev_hardsect_size(sb->s_bdev);
	if (size < minsize)
		size = minsize;
	return sb_set_blocksize(sb, size);
}

EXPORT_SYMBOL(sb_min_blocksize);

static int
blkdev_get_block(struct inode *inode, sector_t iblock,
		struct buffer_head *bh, int create)
{
	if (iblock >= max_block(I_BDEV(inode))) {
		if (create)
			return -EIO;

		/*
		 * for reads, we're just trying to fill a partial page.
		 * return a hole, they will have to call get_block again
		 * before they can fill it, and they will get -EIO at that
		 * time
		 */
		return 0;
	}
	bh->b_bdev = I_BDEV(inode);
	bh->b_blocknr = iblock;
	set_buffer_mapped(bh);
	return 0;
}

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
static int
blkdev_get_blocks(struct inode *inode, sector_t iblock,
		struct buffer_head *bh, int create)
{
	sector_t end_block = max_block(I_BDEV(inode));
	unsigned long max_blocks = bh->b_size >> inode->i_blkbits;

	if ((iblock + max_blocks) > end_block) {
		max_blocks = end_block - iblock;
		if ((long)max_blocks <= 0) {
			if (create)
				return -EIO;	/* write fully beyond EOF */
			/*
			 * It is a read which is fully beyond EOF.  We return
			 * a !buffer_mapped buffer
			 */
			max_blocks = 0;
		}
	}

	bh->b_bdev = I_BDEV(inode);
	bh->b_blocknr = iblock;
	bh->b_size = max_blocks << inode->i_blkbits;
	if (max_blocks)
		set_buffer_mapped(bh);
	return 0;
}

static ssize_t
blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
			loff_t offset, unsigned long nr_segs)
{
	struct file *file = iocb->ki_filp;
	struct inode *inode = file->f_mapping->host;

	return blockdev_direct_IO_no_locking(rw, iocb, inode, I_BDEV(inode),
				iov, offset, nr_segs, blkdev_get_blocks, NULL);
}

Linus Torvalds's avatar
Linus Torvalds committed
177 178 179 180 181 182 183 184 185 186
static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
{
	return block_write_full_page(page, blkdev_get_block, wbc);
}

static int blkdev_readpage(struct file * file, struct page * page)
{
	return block_read_full_page(page, blkdev_get_block);
}

187 188 189
static int blkdev_write_begin(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned flags,
			struct page **pagep, void **fsdata)
Linus Torvalds's avatar
Linus Torvalds committed
190
{
191 192 193
	*pagep = NULL;
	return block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
				blkdev_get_block);
Linus Torvalds's avatar
Linus Torvalds committed
194 195
}

196 197 198
static int blkdev_write_end(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned copied,
			struct page *page, void *fsdata)
Linus Torvalds's avatar
Linus Torvalds committed
199
{
200 201 202 203 204 205 206
	int ret;
	ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);

	unlock_page(page);
	page_cache_release(page);

	return ret;
Linus Torvalds's avatar
Linus Torvalds committed
207 208 209 210
}

/*
 * private llseek:
211
 * for a block special file file->f_path.dentry->d_inode->i_size is zero
Linus Torvalds's avatar
Linus Torvalds committed
212 213 214 215 216 217 218 219
 * so we compute the size by hand (just as in block_read/write above)
 */
static loff_t block_llseek(struct file *file, loff_t offset, int origin)
{
	struct inode *bd_inode = file->f_mapping->host;
	loff_t size;
	loff_t retval;

220
	mutex_lock(&bd_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236
	size = i_size_read(bd_inode);

	switch (origin) {
		case 2:
			offset += size;
			break;
		case 1:
			offset += file->f_pos;
	}
	retval = -EINVAL;
	if (offset >= 0 && offset <= size) {
		if (offset != file->f_pos) {
			file->f_pos = offset;
		}
		retval = offset;
	}
237
	mutex_unlock(&bd_inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255
	return retval;
}
	
/*
 *	Filp is never NULL; the only case when ->fsync() is called with
 *	NULL first argument is nfsd_sync_dir() and that's not a directory.
 */
 
static int block_fsync(struct file *filp, struct dentry *dentry, int datasync)
{
	return sync_blockdev(I_BDEV(filp->f_mapping->host));
}

/*
 * pseudo-fs
 */

static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
256
static struct kmem_cache * bdev_cachep __read_mostly;
Linus Torvalds's avatar
Linus Torvalds committed
257 258 259

static struct inode *bdev_alloc_inode(struct super_block *sb)
{
260
	struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
Linus Torvalds's avatar
Linus Torvalds committed
261 262 263 264 265 266 267 268 269 270 271 272 273
	if (!ei)
		return NULL;
	return &ei->vfs_inode;
}

static void bdev_destroy_inode(struct inode *inode)
{
	struct bdev_inode *bdi = BDEV_I(inode);

	bdi->bdev.bd_inode_backing_dev_info = NULL;
	kmem_cache_free(bdev_cachep, bdi);
}

274
static void init_once(void *foo)
Linus Torvalds's avatar
Linus Torvalds committed
275 276 277 278
{
	struct bdev_inode *ei = (struct bdev_inode *) foo;
	struct block_device *bdev = &ei->bdev;

279 280 281 282 283
	memset(bdev, 0, sizeof(*bdev));
	mutex_init(&bdev->bd_mutex);
	sema_init(&bdev->bd_mount_sem, 1);
	INIT_LIST_HEAD(&bdev->bd_inodes);
	INIT_LIST_HEAD(&bdev->bd_list);
284
#ifdef CONFIG_SYSFS
285
	INIT_LIST_HEAD(&bdev->bd_holder_list);
286
#endif
287
	inode_init_once(&ei->vfs_inode);
Linus Torvalds's avatar
Linus Torvalds committed
288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308
}

static inline void __bd_forget(struct inode *inode)
{
	list_del_init(&inode->i_devices);
	inode->i_bdev = NULL;
	inode->i_mapping = &inode->i_data;
}

static void bdev_clear_inode(struct inode *inode)
{
	struct block_device *bdev = &BDEV_I(inode)->bdev;
	struct list_head *p;
	spin_lock(&bdev_lock);
	while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) {
		__bd_forget(list_entry(p, struct inode, i_devices));
	}
	list_del_init(&bdev->bd_list);
	spin_unlock(&bdev_lock);
}

309
static const struct super_operations bdev_sops = {
Linus Torvalds's avatar
Linus Torvalds committed
310 311 312 313 314 315 316
	.statfs = simple_statfs,
	.alloc_inode = bdev_alloc_inode,
	.destroy_inode = bdev_destroy_inode,
	.drop_inode = generic_delete_inode,
	.clear_inode = bdev_clear_inode,
};

317 318
static int bd_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
Linus Torvalds's avatar
Linus Torvalds committed
319
{
320
	return get_sb_pseudo(fs_type, "bdev:", &bdev_sops, 0x62646576, mnt);
Linus Torvalds's avatar
Linus Torvalds committed
321 322 323 324 325 326 327 328
}

static struct file_system_type bd_type = {
	.name		= "bdev",
	.get_sb		= bd_get_sb,
	.kill_sb	= kill_anon_super,
};

329
static struct vfsmount *bd_mnt __read_mostly;
Linus Torvalds's avatar
Linus Torvalds committed
330 331 332 333 334 335
struct super_block *blockdev_superblock;

void __init bdev_cache_init(void)
{
	int err;
	bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
336 337
			0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
				SLAB_MEM_SPREAD|SLAB_PANIC),
338
			init_once);
Linus Torvalds's avatar
Linus Torvalds committed
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
	err = register_filesystem(&bd_type);
	if (err)
		panic("Cannot register bdev pseudo-fs");
	bd_mnt = kern_mount(&bd_type);
	if (IS_ERR(bd_mnt))
		panic("Cannot create bdev pseudo-fs");
	blockdev_superblock = bd_mnt->mnt_sb;	/* For writeback */
}

/*
 * Most likely _very_ bad one - but then it's hardly critical for small
 * /dev and can be fixed when somebody will need really large one.
 * Keep in mind that it will be fed through icache hash function too.
 */
static inline unsigned long hash(dev_t dev)
{
	return MAJOR(dev)+MINOR(dev);
}

static int bdev_test(struct inode *inode, void *data)
{
	return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
}

static int bdev_set(struct inode *inode, void *data)
{
	BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
	return 0;
}

static LIST_HEAD(all_bdevs);

struct block_device *bdget(dev_t dev)
{
	struct block_device *bdev;
	struct inode *inode;

	inode = iget5_locked(bd_mnt->mnt_sb, hash(dev),
			bdev_test, bdev_set, &dev);

	if (!inode)
		return NULL;

	bdev = &BDEV_I(inode)->bdev;

	if (inode->i_state & I_NEW) {
		bdev->bd_contains = NULL;
		bdev->bd_inode = inode;
		bdev->bd_block_size = (1 << inode->i_blkbits);
		bdev->bd_part_count = 0;
		bdev->bd_invalidated = 0;
		inode->i_mode = S_IFBLK;
		inode->i_rdev = dev;
		inode->i_bdev = bdev;
		inode->i_data.a_ops = &def_blk_aops;
		mapping_set_gfp_mask(&inode->i_data, GFP_USER);
		inode->i_data.backing_dev_info = &default_backing_dev_info;
		spin_lock(&bdev_lock);
		list_add(&bdev->bd_list, &all_bdevs);
		spin_unlock(&bdev_lock);
		unlock_new_inode(inode);
	}
	return bdev;
}

EXPORT_SYMBOL(bdget);

long nr_blockdev_pages(void)
{
408
	struct block_device *bdev;
Linus Torvalds's avatar
Linus Torvalds committed
409 410
	long ret = 0;
	spin_lock(&bdev_lock);
411
	list_for_each_entry(bdev, &all_bdevs, bd_list) {
Linus Torvalds's avatar
Linus Torvalds committed
412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427
		ret += bdev->bd_inode->i_mapping->nrpages;
	}
	spin_unlock(&bdev_lock);
	return ret;
}

void bdput(struct block_device *bdev)
{
	iput(bdev->bd_inode);
}

EXPORT_SYMBOL(bdput);
 
static struct block_device *bd_acquire(struct inode *inode)
{
	struct block_device *bdev;
428

Linus Torvalds's avatar
Linus Torvalds committed
429 430
	spin_lock(&bdev_lock);
	bdev = inode->i_bdev;
431 432
	if (bdev) {
		atomic_inc(&bdev->bd_inode->i_count);
Linus Torvalds's avatar
Linus Torvalds committed
433 434 435 436
		spin_unlock(&bdev_lock);
		return bdev;
	}
	spin_unlock(&bdev_lock);
437

Linus Torvalds's avatar
Linus Torvalds committed
438 439 440
	bdev = bdget(inode->i_rdev);
	if (bdev) {
		spin_lock(&bdev_lock);
441 442 443 444 445 446 447 448 449 450 451 452
		if (!inode->i_bdev) {
			/*
			 * We take an additional bd_inode->i_count for inode,
			 * and it's released in clear_inode() of inode.
			 * So, we can access it via ->i_mapping always
			 * without igrab().
			 */
			atomic_inc(&bdev->bd_inode->i_count);
			inode->i_bdev = bdev;
			inode->i_mapping = bdev->bd_inode->i_mapping;
			list_add(&inode->i_devices, &bdev->bd_inodes);
		}
Linus Torvalds's avatar
Linus Torvalds committed
453 454 455 456 457 458 459 460 461
		spin_unlock(&bdev_lock);
	}
	return bdev;
}

/* Call when you free inode */

void bd_forget(struct inode *inode)
{
462 463
	struct block_device *bdev = NULL;

Linus Torvalds's avatar
Linus Torvalds committed
464
	spin_lock(&bdev_lock);
465 466 467
	if (inode->i_bdev) {
		if (inode->i_sb != blockdev_superblock)
			bdev = inode->i_bdev;
Linus Torvalds's avatar
Linus Torvalds committed
468
		__bd_forget(inode);
469
	}
Linus Torvalds's avatar
Linus Torvalds committed
470
	spin_unlock(&bdev_lock);
471 472 473

	if (bdev)
		iput(bdev->bd_inode);
Linus Torvalds's avatar
Linus Torvalds committed
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
}

int bd_claim(struct block_device *bdev, void *holder)
{
	int res;
	spin_lock(&bdev_lock);

	/* first decide result */
	if (bdev->bd_holder == holder)
		res = 0;	 /* already a holder */
	else if (bdev->bd_holder != NULL)
		res = -EBUSY; 	 /* held by someone else */
	else if (bdev->bd_contains == bdev)
		res = 0;  	 /* is a whole device which isn't held */

	else if (bdev->bd_contains->bd_holder == bd_claim)
		res = 0; 	 /* is a partition of a device that is being partitioned */
	else if (bdev->bd_contains->bd_holder != NULL)
		res = -EBUSY;	 /* is a partition of a held device */
	else
		res = 0;	 /* is a partition of an un-held device */

	/* now impose change */
	if (res==0) {
		/* note that for a whole device bd_holders
		 * will be incremented twice, and bd_holder will
		 * be set to bd_claim before being set to holder
		 */
		bdev->bd_contains->bd_holders ++;
		bdev->bd_contains->bd_holder = bd_claim;
		bdev->bd_holders++;
		bdev->bd_holder = holder;
	}
	spin_unlock(&bdev_lock);
	return res;
}

EXPORT_SYMBOL(bd_claim);

void bd_release(struct block_device *bdev)
{
	spin_lock(&bdev_lock);
	if (!--bdev->bd_contains->bd_holders)
		bdev->bd_contains->bd_holder = NULL;
	if (!--bdev->bd_holders)
		bdev->bd_holder = NULL;
	spin_unlock(&bdev_lock);
}

EXPORT_SYMBOL(bd_release);

525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542
#ifdef CONFIG_SYSFS
/*
 * Functions for bd_claim_by_kobject / bd_release_from_kobject
 *
 *     If a kobject is passed to bd_claim_by_kobject()
 *     and the kobject has a parent directory,
 *     following symlinks are created:
 *        o from the kobject to the claimed bdev
 *        o from "holders" directory of the bdev to the parent of the kobject
 *     bd_release_from_kobject() removes these symlinks.
 *
 *     Example:
 *        If /dev/dm-0 maps to /dev/sda, kobject corresponding to
 *        /sys/block/dm-0/slaves is passed to bd_claim_by_kobject(), then:
 *           /sys/block/dm-0/slaves/sda --> /sys/block/sda
 *           /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
 */

543
static int add_symlink(struct kobject *from, struct kobject *to)
544 545
{
	if (!from || !to)
546 547
		return 0;
	return sysfs_create_link(from, to, kobject_name(to));
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
}

static void del_symlink(struct kobject *from, struct kobject *to)
{
	if (!from || !to)
		return;
	sysfs_remove_link(from, kobject_name(to));
}

/*
 * 'struct bd_holder' contains pointers to kobjects symlinked by
 * bd_claim_by_kobject.
 * It's connected to bd_holder_list which is protected by bdev->bd_sem.
 */
struct bd_holder {
	struct list_head list;	/* chain of holders of the bdev */
	int count;		/* references from the holder */
	struct kobject *sdir;	/* holder object, e.g. "/block/dm-0/slaves" */
	struct kobject *hdev;	/* e.g. "/block/dm-0" */
	struct kobject *hdir;	/* e.g. "/block/sda/holders" */
	struct kobject *sdev;	/* e.g. "/block/sda" */
};

/*
 * Get references of related kobjects at once.
 * Returns 1 on success. 0 on failure.
 *
 * Should call bd_holder_release_dirs() after successful use.
 */
static int bd_holder_grab_dirs(struct block_device *bdev,
			struct bd_holder *bo)
{
	if (!bdev || !bo)
		return 0;

	bo->sdir = kobject_get(bo->sdir);
	if (!bo->sdir)
		return 0;

	bo->hdev = kobject_get(bo->sdir->parent);
	if (!bo->hdev)
		goto fail_put_sdir;

591
	bo->sdev = kobject_get(&part_to_dev(bdev->bd_part)->kobj);
592 593 594
	if (!bo->sdev)
		goto fail_put_hdev;

595
	bo->hdir = kobject_get(bdev->bd_part->holder_dir);
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
	if (!bo->hdir)
		goto fail_put_sdev;

	return 1;

fail_put_sdev:
	kobject_put(bo->sdev);
fail_put_hdev:
	kobject_put(bo->hdev);
fail_put_sdir:
	kobject_put(bo->sdir);

	return 0;
}

/* Put references of related kobjects at once. */
static void bd_holder_release_dirs(struct bd_holder *bo)
{
	kobject_put(bo->hdir);
	kobject_put(bo->sdev);
	kobject_put(bo->hdev);
	kobject_put(bo->sdir);
}

static struct bd_holder *alloc_bd_holder(struct kobject *kobj)
{
	struct bd_holder *bo;

	bo = kzalloc(sizeof(*bo), GFP_KERNEL);
	if (!bo)
		return NULL;

	bo->count = 1;
	bo->sdir = kobj;

	return bo;
}

static void free_bd_holder(struct bd_holder *bo)
{
	kfree(bo);
}

639 640 641 642 643 644 645 646 647 648
/**
 * find_bd_holder - find matching struct bd_holder from the block device
 *
 * @bdev:	struct block device to be searched
 * @bo:		target struct bd_holder
 *
 * Returns matching entry with @bo in @bdev->bd_holder_list.
 * If found, increment the reference count and return the pointer.
 * If not found, returns NULL.
 */
649 650
static struct bd_holder *find_bd_holder(struct block_device *bdev,
					struct bd_holder *bo)
651 652 653 654 655 656 657 658 659 660 661 662
{
	struct bd_holder *tmp;

	list_for_each_entry(tmp, &bdev->bd_holder_list, list)
		if (tmp->sdir == bo->sdir) {
			tmp->count++;
			return tmp;
		}

	return NULL;
}

663 664 665 666 667 668
/**
 * add_bd_holder - create sysfs symlinks for bd_claim() relationship
 *
 * @bdev:	block device to be bd_claimed
 * @bo:		preallocated and initialized by alloc_bd_holder()
 *
669
 * Add @bo to @bdev->bd_holder_list, create symlinks.
670
 *
671 672
 * Returns 0 if symlinks are created.
 * Returns -ve if something fails.
673 674 675
 */
static int add_bd_holder(struct block_device *bdev, struct bd_holder *bo)
{
676
	int err;
677 678

	if (!bo)
679
		return -EINVAL;
680 681

	if (!bd_holder_grab_dirs(bdev, bo))
682
		return -EBUSY;
683

684 685 686 687 688 689 690 691
	err = add_symlink(bo->sdir, bo->sdev);
	if (err)
		return err;

	err = add_symlink(bo->hdir, bo->hdev);
	if (err) {
		del_symlink(bo->sdir, bo->sdev);
		return err;
692
	}
693 694 695

	list_add_tail(&bo->list, &bdev->bd_holder_list);
	return 0;
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
}

/**
 * del_bd_holder - delete sysfs symlinks for bd_claim() relationship
 *
 * @bdev:	block device to be bd_claimed
 * @kobj:	holder's kobject
 *
 * If there is matching entry with @kobj in @bdev->bd_holder_list
 * and no other bd_claim() from the same kobject,
 * remove the struct bd_holder from the list, delete symlinks for it.
 *
 * Returns a pointer to the struct bd_holder when it's removed from the list
 * and ready to be freed.
 * Returns NULL if matching claim isn't found or there is other bd_claim()
 * by the same kobject.
 */
static struct bd_holder *del_bd_holder(struct block_device *bdev,
					struct kobject *kobj)
{
	struct bd_holder *bo;

	list_for_each_entry(bo, &bdev->bd_holder_list, list) {
		if (bo->sdir == kobj) {
			bo->count--;
			BUG_ON(bo->count < 0);
			if (!bo->count) {
				list_del(&bo->list);
				del_symlink(bo->sdir, bo->sdev);
				del_symlink(bo->hdir, bo->hdev);
				bd_holder_release_dirs(bo);
				return bo;
			}
			break;
		}
	}

	return NULL;
}

/**
 * bd_claim_by_kobject - bd_claim() with additional kobject signature
 *
 * @bdev:	block device to be claimed
 * @holder:	holder's signature
 * @kobj:	holder's kobject
 *
 * Do bd_claim() and if it succeeds, create sysfs symlinks between
 * the bdev and the holder's kobject.
 * Use bd_release_from_kobject() when relesing the claimed bdev.
 *
 * Returns 0 on success. (same as bd_claim())
 * Returns errno on failure.
 */
static int bd_claim_by_kobject(struct block_device *bdev, void *holder,
				struct kobject *kobj)
{
753
	int err;
754
	struct bd_holder *bo, *found;
755 756 757 758 759 760 761 762

	if (!kobj)
		return -EINVAL;

	bo = alloc_bd_holder(kobj);
	if (!bo)
		return -ENOMEM;

763
	mutex_lock(&bdev->bd_mutex);
764

765 766
	err = bd_claim(bdev, holder);
	if (err)
767
		goto fail;
768 769 770

	found = find_bd_holder(bdev, bo);
	if (found)
771
		goto fail;
772 773 774 775

	err = add_bd_holder(bdev, bo);
	if (err)
		bd_release(bdev);
776 777 778
	else
		bo = NULL;
fail:
779
	mutex_unlock(&bdev->bd_mutex);
780
	free_bd_holder(bo);
781
	return err;
782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797
}

/**
 * bd_release_from_kobject - bd_release() with additional kobject signature
 *
 * @bdev:	block device to be released
 * @kobj:	holder's kobject
 *
 * Do bd_release() and remove sysfs symlinks created by bd_claim_by_kobject().
 */
static void bd_release_from_kobject(struct block_device *bdev,
					struct kobject *kobj)
{
	if (!kobj)
		return;

798
	mutex_lock(&bdev->bd_mutex);
799
	bd_release(bdev);
800
	free_bd_holder(del_bd_holder(bdev, kobj));
801
	mutex_unlock(&bdev->bd_mutex);
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
}

/**
 * bd_claim_by_disk - wrapper function for bd_claim_by_kobject()
 *
 * @bdev:	block device to be claimed
 * @holder:	holder's signature
 * @disk:	holder's gendisk
 *
 * Call bd_claim_by_kobject() with getting @disk->slave_dir.
 */
int bd_claim_by_disk(struct block_device *bdev, void *holder,
			struct gendisk *disk)
{
	return bd_claim_by_kobject(bdev, holder, kobject_get(disk->slave_dir));
}
EXPORT_SYMBOL_GPL(bd_claim_by_disk);

/**
 * bd_release_from_disk - wrapper function for bd_release_from_kobject()
 *
 * @bdev:	block device to be claimed
 * @disk:	holder's gendisk
 *
 * Call bd_release_from_kobject() and put @disk->slave_dir.
 */
void bd_release_from_disk(struct block_device *bdev, struct gendisk *disk)
{
	bd_release_from_kobject(bdev, disk->slave_dir);
	kobject_put(disk->slave_dir);
}
EXPORT_SYMBOL_GPL(bd_release_from_disk);
#endif

Linus Torvalds's avatar
Linus Torvalds committed
836 837 838 839 840 841 842
/*
 * Tries to open block device by device number.  Use it ONLY if you
 * really do not have anything better - i.e. when you are behind a
 * truly sucky interface and all you are given is a device number.  _Never_
 * to be used for internal purposes.  If you ever need it - reconsider
 * your API.
 */
843
struct block_device *open_by_devnum(dev_t dev, fmode_t mode)
Linus Torvalds's avatar
Linus Torvalds committed
844 845 846 847
{
	struct block_device *bdev = bdget(dev);
	int err = -ENOMEM;
	if (bdev)
848
		err = blkdev_get(bdev, mode);
Linus Torvalds's avatar
Linus Torvalds committed
849 850 851 852 853
	return err ? ERR_PTR(err) : bdev;
}

EXPORT_SYMBOL(open_by_devnum);

854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879
/**
 * flush_disk - invalidates all buffer-cache entries on a disk
 *
 * @bdev:      struct block device to be flushed
 *
 * Invalidates all buffer-cache entries on a disk. It should be called
 * when a disk has been changed -- either by a media change or online
 * resize.
 */
static void flush_disk(struct block_device *bdev)
{
	if (__invalidate_device(bdev)) {
		char name[BDEVNAME_SIZE] = "";

		if (bdev->bd_disk)
			disk_name(bdev->bd_disk, 0, name);
		printk(KERN_WARNING "VFS: busy inodes on changed media or "
		       "resized disk %s\n", name);
	}

	if (!bdev->bd_disk)
		return;
	if (disk_partitionable(bdev->bd_disk))
		bdev->bd_invalidated = 1;
}

880
/**
881
 * check_disk_size_change - checks for disk size change and adjusts bdev size.
882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901
 * @disk: struct gendisk to check
 * @bdev: struct bdev to adjust.
 *
 * This routine checks to see if the bdev size does not match the disk size
 * and adjusts it if it differs.
 */
void check_disk_size_change(struct gendisk *disk, struct block_device *bdev)
{
	loff_t disk_size, bdev_size;

	disk_size = (loff_t)get_capacity(disk) << 9;
	bdev_size = i_size_read(bdev->bd_inode);
	if (disk_size != bdev_size) {
		char name[BDEVNAME_SIZE];

		disk_name(disk, 0, name);
		printk(KERN_INFO
		       "%s: detected capacity change from %lld to %lld\n",
		       name, bdev_size, disk_size);
		i_size_write(bdev->bd_inode, disk_size);
902
		flush_disk(bdev);
903 904 905 906
	}
}
EXPORT_SYMBOL(check_disk_size_change);

907
/**
908
 * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
909 910 911 912 913 914 915 916
 * @disk: struct gendisk to be revalidated
 *
 * This routine is a wrapper for lower-level driver's revalidate_disk
 * call-backs.  It is used to do common pre and post operations needed
 * for all revalidate_disk operations.
 */
int revalidate_disk(struct gendisk *disk)
{
917
	struct block_device *bdev;
918 919 920 921 922
	int ret = 0;

	if (disk->fops->revalidate_disk)
		ret = disk->fops->revalidate_disk(disk);

923 924 925 926 927 928 929 930
	bdev = bdget_disk(disk, 0);
	if (!bdev)
		return ret;

	mutex_lock(&bdev->bd_mutex);
	check_disk_size_change(disk, bdev);
	mutex_unlock(&bdev->bd_mutex);
	bdput(bdev);
931 932 933 934
	return ret;
}
EXPORT_SYMBOL(revalidate_disk);

Linus Torvalds's avatar
Linus Torvalds committed
935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953
/*
 * This routine checks whether a removable media has been changed,
 * and invalidates all buffer-cache-entries in that case. This
 * is a relatively slow routine, so we have to try to minimize using
 * it. Thus it is called only upon a 'mount' or 'open'. This
 * is the best way of combining speed and utility, I think.
 * People changing diskettes in the middle of an operation deserve
 * to lose :-)
 */
int check_disk_change(struct block_device *bdev)
{
	struct gendisk *disk = bdev->bd_disk;
	struct block_device_operations * bdops = disk->fops;

	if (!bdops->media_changed)
		return 0;
	if (!bdops->media_changed(bdev->bd_disk))
		return 0;

954
	flush_disk(bdev);
Linus Torvalds's avatar
Linus Torvalds committed
955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976
	if (bdops->revalidate_disk)
		bdops->revalidate_disk(bdev->bd_disk);
	return 1;
}

EXPORT_SYMBOL(check_disk_change);

void bd_set_size(struct block_device *bdev, loff_t size)
{
	unsigned bsize = bdev_hardsect_size(bdev);

	bdev->bd_inode->i_size = size;
	while (bsize < PAGE_CACHE_SIZE) {
		if (size & bsize)
			break;
		bsize <<= 1;
	}
	bdev->bd_block_size = bsize;
	bdev->bd_inode->i_blkbits = blksize_bits(bsize);
}
EXPORT_SYMBOL(bd_set_size);

977
static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
978

979 980 981 982 983 984 985
/*
 * bd_mutex locking:
 *
 *  mutex_lock(part->bd_mutex)
 *    mutex_lock_nested(whole->bd_mutex, 1)
 */

986
static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
Linus Torvalds's avatar
Linus Torvalds committed
987 988
{
	struct gendisk *disk;
989
	struct hd_struct *part = NULL;
990
	int ret;
991
	int partno;
992 993
	int perm = 0;

994
	if (mode & FMODE_READ)
995
		perm |= MAY_READ;
996
	if (mode & FMODE_WRITE)
997 998 999 1000 1001
		perm |= MAY_WRITE;
	/*
	 * hooks: /n/, see "layering violations".
	 */
	ret = devcgroup_inode_permission(bdev->bd_inode, perm);
1002 1003
	if (ret != 0) {
		bdput(bdev);
1004
		return ret;
1005
	}
1006 1007

	ret = -ENXIO;
1008

Linus Torvalds's avatar
Linus Torvalds committed
1009
	lock_kernel();
1010

1011
	disk = get_gendisk(bdev->bd_dev, &partno);
1012 1013 1014 1015 1016
	if (!disk)
		goto out_unlock_kernel;
	part = disk_get_part(disk, partno);
	if (!part)
		goto out_unlock_kernel;
Linus Torvalds's avatar
Linus Torvalds committed
1017

1018
	mutex_lock_nested(&bdev->bd_mutex, for_part);
Linus Torvalds's avatar
Linus Torvalds committed
1019 1020
	if (!bdev->bd_openers) {
		bdev->bd_disk = disk;
1021
		bdev->bd_part = part;
Linus Torvalds's avatar
Linus Torvalds committed
1022
		bdev->bd_contains = bdev;
1023
		if (!partno) {
Linus Torvalds's avatar
Linus Torvalds committed
1024 1025
			struct backing_dev_info *bdi;
			if (disk->fops->open) {
1026
				ret = disk->fops->open(bdev, mode);
Linus Torvalds's avatar
Linus Torvalds committed
1027
				if (ret)
1028
					goto out_clear;
Linus Torvalds's avatar
Linus Torvalds committed
1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043
			}
			if (!bdev->bd_openers) {
				bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
				bdi = blk_get_backing_dev_info(bdev);
				if (bdi == NULL)
					bdi = &default_backing_dev_info;
				bdev->bd_inode->i_data.backing_dev_info = bdi;
			}
			if (bdev->bd_invalidated)
				rescan_partitions(disk, bdev);
		} else {
			struct block_device *whole;
			whole = bdget_disk(disk, 0);
			ret = -ENOMEM;
			if (!whole)
1044
				goto out_clear;
1045
			BUG_ON(for_part);
1046
			ret = __blkdev_get(whole, mode, 1);
Linus Torvalds's avatar
Linus Torvalds committed
1047
			if (ret)
1048
				goto out_clear;
Linus Torvalds's avatar
Linus Torvalds committed
1049 1050 1051
			bdev->bd_contains = whole;
			bdev->bd_inode->i_data.backing_dev_info =
			   whole->bd_inode->i_data.backing_dev_info;
1052 1053
			if (!(disk->flags & GENHD_FL_UP) ||
			    !part || !part->nr_sects) {
Linus Torvalds's avatar
Linus Torvalds committed
1054
				ret = -ENXIO;
1055
				goto out_clear;
Linus Torvalds's avatar
Linus Torvalds committed
1056
			}
1057
			bd_set_size(bdev, (loff_t)part->nr_sects << 9);
Linus Torvalds's avatar
Linus Torvalds committed
1058 1059
		}
	} else {
1060
		disk_put_part(part);
Linus Torvalds's avatar
Linus Torvalds committed
1061
		put_disk(disk);
1062 1063 1064
		module_put(disk->fops->owner);
		part = NULL;
		disk = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
1065 1066
		if (bdev->bd_contains == bdev) {
			if (bdev->bd_disk->fops->open) {
1067
				ret = bdev->bd_disk->fops->open(bdev, mode);
Linus Torvalds's avatar
Linus Torvalds committed
1068
				if (ret)
1069
					goto out_unlock_bdev;
Linus Torvalds's avatar
Linus Torvalds committed
1070 1071 1072 1073 1074 1075
			}
			if (bdev->bd_invalidated)
				rescan_partitions(bdev->bd_disk, bdev);
		}
	}
	bdev->bd_openers++;
1076 1077
	if (for_part)
		bdev->bd_part_count++;
1078
	mutex_unlock(&bdev->bd_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
1079 1080 1081
	unlock_kernel();
	return 0;

1082
 out_clear:
Linus Torvalds's avatar
Linus Torvalds committed
1083
	bdev->bd_disk = NULL;
1084
	bdev->bd_part = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
1085 1086
	bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
	if (bdev != bdev->bd_contains)
1087
		__blkdev_put(bdev->bd_contains, mode, 1);
Linus Torvalds's avatar
Linus Torvalds committed
1088
	bdev->bd_contains = NULL;
1089
 out_unlock_bdev:
1090
	mutex_unlock(&bdev->bd_mutex);
1091
 out_unlock_kernel:
Linus Torvalds's avatar
Linus Torvalds committed
1092
	unlock_kernel();
1093 1094 1095 1096 1097 1098 1099

	disk_put_part(part);
	if (disk)
		module_put(disk->fops->owner);
	put_disk(disk);
	bdput(bdev);

Linus Torvalds's avatar
Linus Torvalds committed
1100 1101 1102
	return ret;
}

1103
int blkdev_get(struct block_device *bdev, fmode_t mode)
Linus Torvalds's avatar
Linus Torvalds committed
1104
{
1105
	return __blkdev_get(bdev, mode, 0);
1106
}
Linus Torvalds's avatar
Linus Torvalds committed
1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121
EXPORT_SYMBOL(blkdev_get);

static int blkdev_open(struct inode * inode, struct file * filp)
{
	struct block_device *bdev;
	int res;

	/*
	 * Preserve backwards compatibility and allow large file access
	 * even if userspace doesn't ask for it explicitly. Some mkfs
	 * binary needs it. We might want to drop this workaround
	 * during an unstable branch.
	 */
	filp->f_flags |= O_LARGEFILE;

1122 1123 1124 1125 1126 1127 1128
	if (filp->f_flags & O_NDELAY)
		filp->f_mode |= FMODE_NDELAY;
	if (filp->f_flags & O_EXCL)
		filp->f_mode |= FMODE_EXCL;
	if ((filp->f_flags & O_ACCMODE) == 3)
		filp->f_mode |= FMODE_WRITE_IOCTL;

Linus Torvalds's avatar
Linus Torvalds committed
1129
	bdev = bd_acquire(inode);
1130 1131
	if (bdev == NULL)
		return -ENOMEM;
Linus Torvalds's avatar
Linus Torvalds committed
1132

1133 1134 1135
	filp->f_mapping = bdev->bd_inode->i_mapping;

	res = blkdev_get(bdev, filp->f_mode);
Linus Torvalds's avatar
Linus Torvalds committed
1136 1137 1138
	if (res)
		return res;

1139
	if (!(filp->f_mode & FMODE_EXCL))
Linus Torvalds's avatar
Linus Torvalds committed
1140 1141 1142 1143 1144
		return 0;

	if (!(res = bd_claim(bdev, filp)))
		return 0;

1145
	blkdev_put(bdev, filp->f_mode);
Linus Torvalds's avatar
Linus Torvalds committed
1146 1147 1148
	return res;
}

1149
static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
1150 1151 1152
{
	int ret = 0;
	struct gendisk *disk = bdev->bd_disk;
1153
	struct block_device *victim = NULL;
1154

1155
	mutex_lock_nested(&bdev->bd_mutex, for_part);
1156
	lock_kernel();
1157 1158 1159
	if (for_part)
		bdev->bd_part_count--;

1160 1161 1162 1163 1164 1165
	if (!--bdev->bd_openers) {
		sync_blockdev(bdev);
		kill_bdev(bdev);
	}
	if (bdev->bd_contains == bdev) {
		if (disk->fops->release)
1166
			ret = disk->fops->release(disk, mode);
1167 1168 1169 1170 1171 1172
	}
	if (!bdev->bd_openers) {
		struct module *owner = disk->fops->owner;

		put_disk(disk);
		module_put(owner);
1173 1174
		disk_put_part(bdev->bd_part);
		bdev->bd_part = NULL;
1175 1176
		bdev->bd_disk = NULL;
		bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
1177 1178
		if (bdev != bdev->bd_contains)
			victim = bdev->bd_contains;
1179 1180 1181 1182 1183
		bdev->bd_contains = NULL;
	}
	unlock_kernel();
	mutex_unlock(&bdev->bd_mutex);
	bdput(bdev);
1184
	if (victim)
1185
		__blkdev_put(victim, mode, 1);
1186 1187 1188
	return ret;
}

1189
int blkdev_put(struct block_device *bdev, fmode_t mode)
1190
{
1191
	return __blkdev_put(bdev, mode, 0);
1192
}
1193 1194
EXPORT_SYMBOL(blkdev_put);

Linus Torvalds's avatar
Linus Torvalds committed
1195 1196 1197 1198 1199
static int blkdev_close(struct inode * inode, struct file * filp)
{
	struct block_device *bdev = I_BDEV(filp->f_mapping->host);
	if (bdev->bd_holder == filp)
		bd_release(bdev);
1200
	return blkdev_put(bdev, filp->f_mode);
Linus Torvalds's avatar
Linus Torvalds committed
1201 1202
}

1203
static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
Linus Torvalds's avatar
Linus Torvalds committed
1204
{
1205 1206 1207 1208 1209
	struct block_device *bdev = I_BDEV(file->f_mapping->host);
	fmode_t mode = file->f_mode;
	if (file->f_flags & O_NDELAY)
		mode |= FMODE_NDELAY_NOW;
	return blkdev_ioctl(bdev, mode, cmd, arg);
Linus Torvalds's avatar
Linus Torvalds committed
1210 1211
}

1212
static const struct address_space_operations def_blk_aops = {
Linus Torvalds's avatar
Linus Torvalds committed
1213 1214 1215
	.readpage	= blkdev_readpage,
	.writepage	= blkdev_writepage,
	.sync_page	= block_sync_page,
1216 1217
	.write_begin	= blkdev_write_begin,
	.write_end	= blkdev_write_end,
Linus Torvalds's avatar
Linus Torvalds committed
1218 1219 1220 1221
	.writepages	= generic_writepages,
	.direct_IO	= blkdev_direct_IO,
};

1222
const struct file_operations def_blk_fops = {
Linus Torvalds's avatar
Linus Torvalds committed
1223 1224 1225
	.open		= blkdev_open,
	.release	= blkdev_close,
	.llseek		= block_llseek,
1226 1227
	.read		= do_sync_read,
	.write		= do_sync_write,
Linus Torvalds's avatar
Linus Torvalds committed
1228
  	.aio_read	= generic_file_aio_read,
1229
  	.aio_write	= generic_file_aio_write_nolock,
Linus Torvalds's avatar
Linus Torvalds committed
1230 1231
	.mmap		= generic_file_mmap,
	.fsync		= block_fsync,
1232
	.unlocked_ioctl	= block_ioctl,
Linus Torvalds's avatar
Linus Torvalds committed
1233 1234 1235
#ifdef CONFIG_COMPAT
	.compat_ioctl	= compat_blkdev_ioctl,
#endif
1236 1237
	.splice_read	= generic_file_splice_read,
	.splice_write	= generic_file_splice_write,
Linus Torvalds's avatar
Linus Torvalds committed
1238 1239 1240 1241 1242 1243 1244
};

int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
{
	int res;
	mm_segment_t old_fs = get_fs();
	set_fs(KERNEL_DS);
1245
	res = blkdev_ioctl(bdev, 0, cmd, arg);
Linus Torvalds's avatar
Linus Torvalds committed
1246 1247 1248 1249 1250 1251 1252 1253
	set_fs(old_fs);
	return res;
}

EXPORT_SYMBOL(ioctl_by_bdev);

/**
 * lookup_bdev  - lookup a struct block_device by name
1254
 * @path:	special file representing the block device
Linus Torvalds's avatar
Linus Torvalds committed
1255
 *
1256
 * Get a reference to the blockdevice at @pathname in the current
Linus Torvalds's avatar
Linus Torvalds committed
1257 1258 1259
 * namespace if possible and return it.  Return ERR_PTR(error)
 * otherwise.
 */
1260
struct block_device *lookup_bdev(const char *pathname)
Linus Torvalds's avatar
Linus Torvalds committed
1261 1262 1263
{
	struct block_device *bdev;
	struct inode *inode;
1264
	struct path path;
Linus Torvalds's avatar
Linus Torvalds committed
1265 1266
	int error;

1267
	if (!pathname || !*pathname)
Linus Torvalds's avatar
Linus Torvalds committed
1268 1269
		return ERR_PTR(-EINVAL);

1270
	error = kern_path(pathname, LOOKUP_FOLLOW, &path);
Linus Torvalds's avatar
Linus Torvalds committed
1271 1272 1273
	if (error)
		return ERR_PTR(error);

1274
	inode = path.dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
1275 1276 1277 1278
	error = -ENOTBLK;
	if (!S_ISBLK(inode->i_mode))
		goto fail;
	error = -EACCES;
1279
	if (path.mnt->mnt_flags & MNT_NODEV)
Linus Torvalds's avatar
Linus Torvalds committed
1280 1281 1282 1283 1284 1285
		goto fail;
	error = -ENOMEM;
	bdev = bd_acquire(inode);
	if (!bdev)
		goto fail;
out:
1286
	path_put(&path);
Linus Torvalds's avatar
Linus Torvalds committed
1287 1288 1289 1290 1291
	return bdev;
fail:
	bdev = ERR_PTR(error);
	goto out;
}
1292
EXPORT_SYMBOL(lookup_bdev);
Linus Torvalds's avatar
Linus Torvalds committed
1293 1294

/**
1295
 * open_bdev_exclusive  -  open a block device by name and set it up for use
Linus Torvalds's avatar
Linus Torvalds committed
1296 1297
 *
 * @path:	special file representing the block device
1298
 * @mode:	FMODE_... combination to pass be used
Linus Torvalds's avatar
Linus Torvalds committed
1299 1300 1301 1302 1303
 * @holder:	owner for exclusion
 *
 * Open the blockdevice described by the special file at @path, claim it
 * for the @holder.
 */
1304
struct block_device *open_bdev_exclusive(const char *path, fmode_t mode, void *holder)
Linus Torvalds's avatar
Linus Torvalds committed
1305 1306 1307 1308 1309 1310 1311 1312
{
	struct block_device *bdev;
	int error = 0;

	bdev = lookup_bdev(path);
	if (IS_ERR(bdev))
		return bdev;

1313
	error = blkdev_get(bdev, mode);
Linus Torvalds's avatar
Linus Torvalds committed
1314 1315 1316
	if (error)
		return ERR_PTR(error);
	error = -EACCES;
1317
	if ((mode & FMODE_WRITE) && bdev_read_only(bdev))
Linus Torvalds's avatar
Linus Torvalds committed
1318 1319 1320 1321 1322 1323 1324 1325
		goto blkdev_put;
	error = bd_claim(bdev, holder);
	if (error)
		goto blkdev_put;

	return bdev;
	
blkdev_put:
1326
	blkdev_put(bdev, mode);
Linus Torvalds's avatar
Linus Torvalds committed
1327 1328 1329
	return ERR_PTR(error);
}

1330
EXPORT_SYMBOL(open_bdev_exclusive);
Linus Torvalds's avatar
Linus Torvalds committed
1331 1332

/**
1333
 * close_bdev_exclusive  -  close a blockdevice opened by open_bdev_exclusive()
Linus Torvalds's avatar
Linus Torvalds committed
1334 1335
 *
 * @bdev:	blockdevice to close
1336
 * @mode:	mode, must match that used to open.
Linus Torvalds's avatar
Linus Torvalds committed
1337
 *
1338
 * This is the counterpart to open_bdev_exclusive().
Linus Torvalds's avatar
Linus Torvalds committed
1339
 */
1340
void close_bdev_exclusive(struct block_device *bdev, fmode_t mode)
Linus Torvalds's avatar
Linus Torvalds committed
1341 1342
{
	bd_release(bdev);
1343
	blkdev_put(bdev, mode);
Linus Torvalds's avatar
Linus Torvalds committed
1344 1345
}

1346
EXPORT_SYMBOL(close_bdev_exclusive);
1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363

int __invalidate_device(struct block_device *bdev)
{
	struct super_block *sb = get_super(bdev);
	int res = 0;

	if (sb) {
		/*
		 * no need to lock the super, get_super holds the
		 * read mutex so the filesystem cannot go away
		 * under us (->put_super runs with the write lock
		 * hold).
		 */
		shrink_dcache_sb(sb);
		res = invalidate_inodes(sb);
		drop_super(sb);
	}
1364
	invalidate_bdev(bdev);
1365 1366 1367
	return res;
}
EXPORT_SYMBOL(__invalidate_device);