block_dev.c 30.0 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
/*
 *  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>
#include <linux/highmem.h>
#include <linux/blkdev.h>
#include <linux/module.h>
#include <linux/blkpg.h>
#include <linux/buffer_head.h>
20
#include <linux/writeback.h>
L
Linus Torvalds 已提交
21 22 23 24 25
#include <linux/mpage.h>
#include <linux/mount.h>
#include <linux/uio.h>
#include <linux/namei.h>
#include <asm/uaccess.h>
26
#include "internal.h"
L
Linus Torvalds 已提交
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

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

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;
}

/* Kill _all_ buffers, dirty or not.. */
static void kill_bdev(struct block_device *bdev)
{
	invalidate_bdev(bdev, 1);
	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 */
	if (size > PAGE_SIZE || size < 512 || (size & (size-1)))
		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;
94
	sb->s_blocksize_bits = blksize_bits(size);
L
Linus Torvalds 已提交
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
	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;
}

static int
blkdev_get_blocks(struct inode *inode, sector_t iblock,
134
		struct buffer_head *bh, int create)
L
Linus Torvalds 已提交
135 136
{
	sector_t end_block = max_block(I_BDEV(inode));
137
	unsigned long max_blocks = bh->b_size >> inode->i_blkbits;
L
Linus Torvalds 已提交
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

	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);
}

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);
}

static int blkdev_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
{
	return block_prepare_write(page, from, to, blkdev_get_block);
}

static int blkdev_commit_write(struct file *file, struct page *page, unsigned from, unsigned to)
{
	return block_commit_write(page, from, to);
}

/*
 * private llseek:
 * for a block special file file->f_dentry->d_inode->i_size is zero
 * 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;

202
	mutex_lock(&bd_inode->i_mutex);
L
Linus Torvalds 已提交
203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218
	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;
	}
219
	mutex_unlock(&bd_inode->i_mutex);
L
Linus Torvalds 已提交
220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237
	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);
238
static struct kmem_cache * bdev_cachep __read_mostly;
L
Linus Torvalds 已提交
239 240 241

static struct inode *bdev_alloc_inode(struct super_block *sb)
{
242
	struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
243 244 245 246 247 248 249 250 251 252 253 254 255
	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);
}

256
static void init_once(void * foo, struct kmem_cache * cachep, unsigned long flags)
L
Linus Torvalds 已提交
257 258 259 260 261 262 263 264
{
	struct bdev_inode *ei = (struct bdev_inode *) foo;
	struct block_device *bdev = &ei->bdev;

	if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
	    SLAB_CTOR_CONSTRUCTOR)
	{
		memset(bdev, 0, sizeof(*bdev));
265 266
		mutex_init(&bdev->bd_mutex);
		mutex_init(&bdev->bd_mount_mutex);
L
Linus Torvalds 已提交
267 268
		INIT_LIST_HEAD(&bdev->bd_inodes);
		INIT_LIST_HEAD(&bdev->bd_list);
269 270 271
#ifdef CONFIG_SYSFS
		INIT_LIST_HEAD(&bdev->bd_holder_list);
#endif
L
Linus Torvalds 已提交
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
		inode_init_once(&ei->vfs_inode);
	}
}

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);
}

static struct super_operations bdev_sops = {
	.statfs = simple_statfs,
	.alloc_inode = bdev_alloc_inode,
	.destroy_inode = bdev_destroy_inode,
	.drop_inode = generic_delete_inode,
	.clear_inode = bdev_clear_inode,
};

303 304
static int bd_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
L
Linus Torvalds 已提交
305
{
306
	return get_sb_pseudo(fs_type, "bdev:", &bdev_sops, 0x62646576, mnt);
L
Linus Torvalds 已提交
307 308 309 310 311 312 313 314
}

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

315
static struct vfsmount *bd_mnt __read_mostly;
L
Linus Torvalds 已提交
316 317 318 319 320 321
struct super_block *blockdev_superblock;

void __init bdev_cache_init(void)
{
	int err;
	bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
322 323
			0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
				SLAB_MEM_SPREAD|SLAB_PANIC),
L
Linus Torvalds 已提交
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
			init_once, NULL);
	err = register_filesystem(&bd_type);
	if (err)
		panic("Cannot register bdev pseudo-fs");
	bd_mnt = kern_mount(&bd_type);
	err = PTR_ERR(bd_mnt);
	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)
{
	struct list_head *p;
	long ret = 0;
	spin_lock(&bdev_lock);
	list_for_each(p, &all_bdevs) {
		struct block_device *bdev;
		bdev = list_entry(p, struct block_device, bd_list);
		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;
417

L
Linus Torvalds 已提交
418 419
	spin_lock(&bdev_lock);
	bdev = inode->i_bdev;
420 421
	if (bdev) {
		atomic_inc(&bdev->bd_inode->i_count);
L
Linus Torvalds 已提交
422 423 424 425
		spin_unlock(&bdev_lock);
		return bdev;
	}
	spin_unlock(&bdev_lock);
426

L
Linus Torvalds 已提交
427 428 429
	bdev = bdget(inode->i_rdev);
	if (bdev) {
		spin_lock(&bdev_lock);
430 431 432 433 434 435 436 437 438 439 440 441
		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);
		}
L
Linus Torvalds 已提交
442 443 444 445 446 447 448 449 450
		spin_unlock(&bdev_lock);
	}
	return bdev;
}

/* Call when you free inode */

void bd_forget(struct inode *inode)
{
451 452
	struct block_device *bdev = NULL;

L
Linus Torvalds 已提交
453
	spin_lock(&bdev_lock);
454 455 456
	if (inode->i_bdev) {
		if (inode->i_sb != blockdev_superblock)
			bdev = inode->i_bdev;
L
Linus Torvalds 已提交
457
		__bd_forget(inode);
458
	}
L
Linus Torvalds 已提交
459
	spin_unlock(&bdev_lock);
460 461 462

	if (bdev)
		iput(bdev->bd_inode);
L
Linus Torvalds 已提交
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
}

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);

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
#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
 */

static struct kobject *bdev_get_kobj(struct block_device *bdev)
{
	if (bdev->bd_contains != bdev)
		return kobject_get(&bdev->bd_part->kobj);
	else
		return kobject_get(&bdev->bd_disk->kobj);
}

static struct kobject *bdev_get_holder(struct block_device *bdev)
{
	if (bdev->bd_contains != bdev)
		return kobject_get(bdev->bd_part->holder_dir);
	else
		return kobject_get(bdev->bd_disk->holder_dir);
}

548
static int add_symlink(struct kobject *from, struct kobject *to)
549 550
{
	if (!from || !to)
551 552
		return 0;
	return sysfs_create_link(from, to, kobject_name(to));
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
}

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;

	bo->sdev = bdev_get_kobj(bdev);
	if (!bo->sdev)
		goto fail_put_hdev;

	bo->hdir = bdev_get_holder(bdev);
	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);
}

J
Jun'ichi Nomura 已提交
644 645 646 647 648 649 650 651 652 653
/**
 * 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.
 */
A
Andrew Morton 已提交
654 655
static struct bd_holder *find_bd_holder(struct block_device *bdev,
					struct bd_holder *bo)
J
Jun'ichi Nomura 已提交
656 657 658 659 660 661 662 663 664 665 666 667
{
	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;
}

668 669 670 671 672 673
/**
 * 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()
 *
J
Jun'ichi Nomura 已提交
674
 * Add @bo to @bdev->bd_holder_list, create symlinks.
675
 *
J
Jun'ichi Nomura 已提交
676 677
 * Returns 0 if symlinks are created.
 * Returns -ve if something fails.
678 679 680
 */
static int add_bd_holder(struct block_device *bdev, struct bd_holder *bo)
{
681
	int ret;
682 683

	if (!bo)
684
		return -EINVAL;
685 686

	if (!bd_holder_grab_dirs(bdev, bo))
687
		return -EBUSY;
688

689 690 691 692 693 694 695 696 697
	ret = add_symlink(bo->sdir, bo->sdev);
	if (ret == 0) {
		ret = add_symlink(bo->hdir, bo->hdev);
		if (ret)
			del_symlink(bo->sdir, bo->sdev);
	}
	if (ret == 0)
		list_add_tail(&bo->list, &bdev->bd_holder_list);
	return ret;
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
}

/**
 * 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)
{
	int res;
J
Jun'ichi Nomura 已提交
756
	struct bd_holder *bo, *found;
757 758 759 760 761 762 763 764

	if (!kobj)
		return -EINVAL;

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

765
	mutex_lock(&bdev->bd_mutex);
766
	res = bd_claim(bdev, holder);
767
	if (res == 0) {
J
Jun'ichi Nomura 已提交
768 769 770 771 772 773
		found = find_bd_holder(bdev, bo);
		if (found == NULL) {
			res = add_bd_holder(bdev, bo);
			if (res)
				bd_release(bdev);
		}
774
	}
J
Jun'ichi Nomura 已提交
775 776

	if (res || found)
777
		free_bd_holder(bo);
778
	mutex_unlock(&bdev->bd_mutex);
779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798

	return res;
}

/**
 * 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)
{
	struct bd_holder *bo;

	if (!kobj)
		return;

799
	mutex_lock(&bdev->bd_mutex);
800 801 802
	bd_release(bdev);
	if ((bo = del_bd_holder(bdev, kobj)))
		free_bd_holder(bo);
803
	mutex_unlock(&bdev->bd_mutex);
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
}

/**
 * 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

L
Linus Torvalds 已提交
838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875
/*
 * 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.
 */
struct block_device *open_by_devnum(dev_t dev, unsigned mode)
{
	struct block_device *bdev = bdget(dev);
	int err = -ENOMEM;
	int flags = mode & FMODE_WRITE ? O_RDWR : O_RDONLY;
	if (bdev)
		err = blkdev_get(bdev, mode, flags);
	return err ? ERR_PTR(err) : bdev;
}

EXPORT_SYMBOL(open_by_devnum);

/*
 * 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;

876
	if (__invalidate_device(bdev))
L
Linus Torvalds 已提交
877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902
		printk("VFS: busy inodes on changed media.\n");

	if (bdops->revalidate_disk)
		bdops->revalidate_disk(bdev->bd_disk);
	if (bdev->bd_disk->minors > 1)
		bdev->bd_invalidated = 1;
	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);

903 904
static int __blkdev_get(struct block_device *bdev, mode_t mode, unsigned flags,
			int for_part);
905
static int __blkdev_put(struct block_device *bdev, int for_part);
906 907

static int do_open(struct block_device *bdev, struct file *file, int for_part)
L
Linus Torvalds 已提交
908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923
{
	struct module *owner = NULL;
	struct gendisk *disk;
	int ret = -ENXIO;
	int part;

	file->f_mapping = bdev->bd_inode->i_mapping;
	lock_kernel();
	disk = get_gendisk(bdev->bd_dev, &part);
	if (!disk) {
		unlock_kernel();
		bdput(bdev);
		return ret;
	}
	owner = disk->fops->owner;

924
	mutex_lock_nested(&bdev->bd_mutex, for_part);
L
Linus Torvalds 已提交
925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950
	if (!bdev->bd_openers) {
		bdev->bd_disk = disk;
		bdev->bd_contains = bdev;
		if (!part) {
			struct backing_dev_info *bdi;
			if (disk->fops->open) {
				ret = disk->fops->open(bdev->bd_inode, file);
				if (ret)
					goto out_first;
			}
			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 hd_struct *p;
			struct block_device *whole;
			whole = bdget_disk(disk, 0);
			ret = -ENOMEM;
			if (!whole)
				goto out_first;
951 952
			BUG_ON(for_part);
			ret = __blkdev_get(whole, file->f_mode, file->f_flags, 1);
L
Linus Torvalds 已提交
953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980
			if (ret)
				goto out_first;
			bdev->bd_contains = whole;
			p = disk->part[part - 1];
			bdev->bd_inode->i_data.backing_dev_info =
			   whole->bd_inode->i_data.backing_dev_info;
			if (!(disk->flags & GENHD_FL_UP) || !p || !p->nr_sects) {
				ret = -ENXIO;
				goto out_first;
			}
			kobject_get(&p->kobj);
			bdev->bd_part = p;
			bd_set_size(bdev, (loff_t) p->nr_sects << 9);
		}
	} else {
		put_disk(disk);
		module_put(owner);
		if (bdev->bd_contains == bdev) {
			if (bdev->bd_disk->fops->open) {
				ret = bdev->bd_disk->fops->open(bdev->bd_inode, file);
				if (ret)
					goto out;
			}
			if (bdev->bd_invalidated)
				rescan_partitions(bdev->bd_disk, bdev);
		}
	}
	bdev->bd_openers++;
981 982
	if (for_part)
		bdev->bd_part_count++;
983
	mutex_unlock(&bdev->bd_mutex);
L
Linus Torvalds 已提交
984 985 986 987 988 989 990
	unlock_kernel();
	return 0;

out_first:
	bdev->bd_disk = NULL;
	bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
	if (bdev != bdev->bd_contains)
991
		__blkdev_put(bdev->bd_contains, 1);
L
Linus Torvalds 已提交
992 993 994 995
	bdev->bd_contains = NULL;
	put_disk(disk);
	module_put(owner);
out:
996
	mutex_unlock(&bdev->bd_mutex);
L
Linus Torvalds 已提交
997 998 999 1000 1001 1002
	unlock_kernel();
	if (ret)
		bdput(bdev);
	return ret;
}

1003 1004
static int __blkdev_get(struct block_device *bdev, mode_t mode, unsigned flags,
			int for_part)
L
Linus Torvalds 已提交
1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018
{
	/*
	 * This crockload is due to bad choice of ->open() type.
	 * It will go away.
	 * For now, block device ->open() routine must _not_
	 * examine anything in 'inode' argument except ->i_rdev.
	 */
	struct file fake_file = {};
	struct dentry fake_dentry = {};
	fake_file.f_mode = mode;
	fake_file.f_flags = flags;
	fake_file.f_dentry = &fake_dentry;
	fake_dentry.d_inode = bdev->bd_inode;

1019
	return do_open(bdev, &fake_file, for_part);
L
Linus Torvalds 已提交
1020 1021
}

1022 1023 1024 1025
int blkdev_get(struct block_device *bdev, mode_t mode, unsigned flags)
{
	return __blkdev_get(bdev, mode, flags, 0);
}
L
Linus Torvalds 已提交
1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041
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;

	bdev = bd_acquire(inode);
1042 1043
	if (bdev == NULL)
		return -ENOMEM;
L
Linus Torvalds 已提交
1044

1045
	res = do_open(bdev, filp, 0);
L
Linus Torvalds 已提交
1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058
	if (res)
		return res;

	if (!(filp->f_flags & O_EXCL) )
		return 0;

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

	blkdev_put(bdev);
	return res;
}

1059
static int __blkdev_put(struct block_device *bdev, int for_part)
1060 1061 1062 1063
{
	int ret = 0;
	struct inode *bd_inode = bdev->bd_inode;
	struct gendisk *disk = bdev->bd_disk;
1064
	struct block_device *victim = NULL;
1065

1066
	mutex_lock_nested(&bdev->bd_mutex, for_part);
1067
	lock_kernel();
1068 1069 1070
	if (for_part)
		bdev->bd_part_count--;

1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090
	if (!--bdev->bd_openers) {
		sync_blockdev(bdev);
		kill_bdev(bdev);
	}
	if (bdev->bd_contains == bdev) {
		if (disk->fops->release)
			ret = disk->fops->release(bd_inode, NULL);
	}
	if (!bdev->bd_openers) {
		struct module *owner = disk->fops->owner;

		put_disk(disk);
		module_put(owner);

		if (bdev->bd_contains != bdev) {
			kobject_put(&bdev->bd_part->kobj);
			bdev->bd_part = NULL;
		}
		bdev->bd_disk = NULL;
		bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
1091 1092
		if (bdev != bdev->bd_contains)
			victim = bdev->bd_contains;
1093 1094 1095 1096 1097
		bdev->bd_contains = NULL;
	}
	unlock_kernel();
	mutex_unlock(&bdev->bd_mutex);
	bdput(bdev);
1098 1099
	if (victim)
		__blkdev_put(victim, 1);
1100 1101 1102
	return ret;
}

1103 1104 1105 1106
int blkdev_put(struct block_device *bdev)
{
	return __blkdev_put(bdev, 0);
}
1107 1108
EXPORT_SYMBOL(blkdev_put);

L
Linus Torvalds 已提交
1109 1110 1111 1112 1113 1114 1115 1116
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);
	return blkdev_put(bdev);
}

1117
static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
L
Linus Torvalds 已提交
1118 1119 1120 1121
{
	return blkdev_ioctl(file->f_mapping->host, file, cmd, arg);
}

1122
const struct address_space_operations def_blk_aops = {
L
Linus Torvalds 已提交
1123 1124 1125 1126 1127 1128 1129 1130 1131
	.readpage	= blkdev_readpage,
	.writepage	= blkdev_writepage,
	.sync_page	= block_sync_page,
	.prepare_write	= blkdev_prepare_write,
	.commit_write	= blkdev_commit_write,
	.writepages	= generic_writepages,
	.direct_IO	= blkdev_direct_IO,
};

1132
const struct file_operations def_blk_fops = {
L
Linus Torvalds 已提交
1133 1134 1135
	.open		= blkdev_open,
	.release	= blkdev_close,
	.llseek		= block_llseek,
1136 1137
	.read		= do_sync_read,
	.write		= do_sync_write,
L
Linus Torvalds 已提交
1138
  	.aio_read	= generic_file_aio_read,
1139
  	.aio_write	= generic_file_aio_write_nolock,
L
Linus Torvalds 已提交
1140 1141
	.mmap		= generic_file_mmap,
	.fsync		= block_fsync,
1142
	.unlocked_ioctl	= block_ioctl,
L
Linus Torvalds 已提交
1143 1144 1145 1146
#ifdef CONFIG_COMPAT
	.compat_ioctl	= compat_blkdev_ioctl,
#endif
	.sendfile	= generic_file_sendfile,
1147 1148
	.splice_read	= generic_file_splice_read,
	.splice_write	= generic_file_splice_write,
L
Linus Torvalds 已提交
1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259
};

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);
	res = blkdev_ioctl(bdev->bd_inode, NULL, cmd, arg);
	set_fs(old_fs);
	return res;
}

EXPORT_SYMBOL(ioctl_by_bdev);

/**
 * lookup_bdev  - lookup a struct block_device by name
 *
 * @path:	special file representing the block device
 *
 * Get a reference to the blockdevice at @path in the current
 * namespace if possible and return it.  Return ERR_PTR(error)
 * otherwise.
 */
struct block_device *lookup_bdev(const char *path)
{
	struct block_device *bdev;
	struct inode *inode;
	struct nameidata nd;
	int error;

	if (!path || !*path)
		return ERR_PTR(-EINVAL);

	error = path_lookup(path, LOOKUP_FOLLOW, &nd);
	if (error)
		return ERR_PTR(error);

	inode = nd.dentry->d_inode;
	error = -ENOTBLK;
	if (!S_ISBLK(inode->i_mode))
		goto fail;
	error = -EACCES;
	if (nd.mnt->mnt_flags & MNT_NODEV)
		goto fail;
	error = -ENOMEM;
	bdev = bd_acquire(inode);
	if (!bdev)
		goto fail;
out:
	path_release(&nd);
	return bdev;
fail:
	bdev = ERR_PTR(error);
	goto out;
}

/**
 * open_bdev_excl  -  open a block device by name and set it up for use
 *
 * @path:	special file representing the block device
 * @flags:	%MS_RDONLY for opening read-only
 * @holder:	owner for exclusion
 *
 * Open the blockdevice described by the special file at @path, claim it
 * for the @holder.
 */
struct block_device *open_bdev_excl(const char *path, int flags, void *holder)
{
	struct block_device *bdev;
	mode_t mode = FMODE_READ;
	int error = 0;

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

	if (!(flags & MS_RDONLY))
		mode |= FMODE_WRITE;
	error = blkdev_get(bdev, mode, 0);
	if (error)
		return ERR_PTR(error);
	error = -EACCES;
	if (!(flags & MS_RDONLY) && bdev_read_only(bdev))
		goto blkdev_put;
	error = bd_claim(bdev, holder);
	if (error)
		goto blkdev_put;

	return bdev;
	
blkdev_put:
	blkdev_put(bdev);
	return ERR_PTR(error);
}

EXPORT_SYMBOL(open_bdev_excl);

/**
 * close_bdev_excl  -  release a blockdevice openen by open_bdev_excl()
 *
 * @bdev:	blockdevice to close
 *
 * This is the counterpart to open_bdev_excl().
 */
void close_bdev_excl(struct block_device *bdev)
{
	bd_release(bdev);
	blkdev_put(bdev);
}

EXPORT_SYMBOL(close_bdev_excl);
1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280

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);
	}
	invalidate_bdev(bdev, 0);
	return res;
}
EXPORT_SYMBOL(__invalidate_device);