block_dev.c 34.8 KB
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/*
 *  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>
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#include <linux/writeback.h>
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#include <linux/mpage.h>
#include <linux/mount.h>
#include <linux/uio.h>
#include <linux/namei.h>
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#include <linux/log2.h>
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#include <asm/uaccess.h>
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#include "internal.h"
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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;
}

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/* Kill _all_ buffers and pagecache , dirty or not.. */
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static void kill_bdev(struct block_device *bdev)
{
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	if (bdev->bd_inode->i_mapping->nrpages == 0)
		return;
	invalidate_bh_lrus();
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	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 */
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	if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
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		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;
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	sb->s_blocksize_bits = blksize_bits(size);
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	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;
}

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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);
}

#if 0
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static int blk_end_aio(struct bio *bio, unsigned int bytes_done, int error)
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{
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	struct kiocb *iocb = bio->bi_private;
	atomic_t *bio_count = &iocb->ki_bio_count;

	if (bio_data_dir(bio) == READ)
		bio_check_pages_dirty(bio);
	else {
		bio_release_pages(bio);
		bio_put(bio);
	}

	/* iocb->ki_nbytes stores error code from LLDD */
	if (error)
		iocb->ki_nbytes = -EIO;

	if (atomic_dec_and_test(bio_count)) {
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		if ((long)iocb->ki_nbytes < 0)
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			aio_complete(iocb, iocb->ki_nbytes, 0);
		else
			aio_complete(iocb, iocb->ki_left, 0);
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	}

	return 0;
}

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#define VEC_SIZE	16
struct pvec {
	unsigned short nr;
	unsigned short idx;
	struct page *page[VEC_SIZE];
};

#define PAGES_SPANNED(addr, len)	\
	(DIV_ROUND_UP((addr) + (len), PAGE_SIZE) - (addr) / PAGE_SIZE);

/*
 * get page pointer for user addr, we internally cache struct page array for
 * (addr, count) range in pvec to avoid frequent call to get_user_pages.  If
 * internal page list is exhausted, a batch count of up to VEC_SIZE is used
 * to get next set of page struct.
 */
static struct page *blk_get_page(unsigned long addr, size_t count, int rw,
				 struct pvec *pvec)
{
	int ret, nr_pages;
	if (pvec->idx == pvec->nr) {
		nr_pages = PAGES_SPANNED(addr, count);
		nr_pages = min(nr_pages, VEC_SIZE);
		down_read(&current->mm->mmap_sem);
		ret = get_user_pages(current, current->mm, addr, nr_pages,
				     rw == READ, 0, pvec->page, NULL);
		up_read(&current->mm->mmap_sem);
		if (ret < 0)
			return ERR_PTR(ret);
		pvec->nr = ret;
		pvec->idx = 0;
	}
	return pvec->page[pvec->idx++];
}

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/* return a page back to pvec array */
static void blk_unget_page(struct page *page, struct pvec *pvec)
{
	pvec->page[--pvec->idx] = page;
}

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static ssize_t
blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
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		 loff_t pos, unsigned long nr_segs)
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{
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	struct inode *inode = iocb->ki_filp->f_mapping->host;
	unsigned blkbits = blksize_bits(bdev_hardsect_size(I_BDEV(inode)));
	unsigned blocksize_mask = (1 << blkbits) - 1;
	unsigned long seg = 0;	/* iov segment iterator */
	unsigned long nvec;	/* number of bio vec needed */
	unsigned long cur_off;	/* offset into current page */
	unsigned long cur_len;	/* I/O len of current page, up to PAGE_SIZE */

	unsigned long addr;	/* user iovec address */
	size_t count;		/* user iovec len */
	size_t nbytes = iocb->ki_nbytes = iocb->ki_left; /* total xfer size */
	loff_t size;		/* size of block device */
	struct bio *bio;
	atomic_t *bio_count = &iocb->ki_bio_count;
	struct page *page;
	struct pvec pvec;

	pvec.nr = 0;
	pvec.idx = 0;

	if (pos & blocksize_mask)
		return -EINVAL;

	size = i_size_read(inode);
	if (pos + nbytes > size) {
		nbytes = size - pos;
		iocb->ki_left = nbytes;
	}

	/*
	 * check first non-zero iov alignment, the remaining
	 * iov alignment is checked inside bio loop below.
	 */
	do {
		addr = (unsigned long) iov[seg].iov_base;
		count = min(iov[seg].iov_len, nbytes);
		if (addr & blocksize_mask || count & blocksize_mask)
			return -EINVAL;
	} while (!count && ++seg < nr_segs);
	atomic_set(bio_count, 1);

	while (nbytes) {
		/* roughly estimate number of bio vec needed */
		nvec = (nbytes + PAGE_SIZE - 1) / PAGE_SIZE;
		nvec = max(nvec, nr_segs - seg);
		nvec = min(nvec, (unsigned long) BIO_MAX_PAGES);

		/* bio_alloc should not fail with GFP_KERNEL flag */
		bio = bio_alloc(GFP_KERNEL, nvec);
		bio->bi_bdev = I_BDEV(inode);
		bio->bi_end_io = blk_end_aio;
		bio->bi_private = iocb;
		bio->bi_sector = pos >> blkbits;
same_bio:
		cur_off = addr & ~PAGE_MASK;
		cur_len = PAGE_SIZE - cur_off;
		if (count < cur_len)
			cur_len = count;

		page = blk_get_page(addr, count, rw, &pvec);
		if (unlikely(IS_ERR(page)))
			goto backout;

		if (bio_add_page(bio, page, cur_len, cur_off)) {
			pos += cur_len;
			addr += cur_len;
			count -= cur_len;
			nbytes -= cur_len;

			if (count)
				goto same_bio;
			while (++seg < nr_segs) {
				addr = (unsigned long) iov[seg].iov_base;
				count = iov[seg].iov_len;
				if (!count)
					continue;
				if (unlikely(addr & blocksize_mask ||
					     count & blocksize_mask)) {
					page = ERR_PTR(-EINVAL);
					goto backout;
				}
				count = min(count, nbytes);
				goto same_bio;
			}
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		} else {
			blk_unget_page(page, &pvec);
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		}

		/* bio is ready, submit it */
		if (rw == READ)
			bio_set_pages_dirty(bio);
		atomic_inc(bio_count);
		submit_bio(rw, bio);
	}

completion:
	iocb->ki_left -= nbytes;
	nbytes = iocb->ki_left;
	iocb->ki_pos += nbytes;

	blk_run_address_space(inode->i_mapping);
	if (atomic_dec_and_test(bio_count))
		aio_complete(iocb, nbytes, 0);

	return -EIOCBQUEUED;

backout:
	/*
	 * back out nbytes count constructed so far for this bio,
	 * we will throw away current bio.
	 */
	nbytes += bio->bi_size;
	bio_release_pages(bio);
	bio_put(bio);
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	/*
	 * if no bio was submmitted, return the error code.
	 * otherwise, proceed with pending I/O completion.
	 */
	if (atomic_read(bio_count) == 1)
		return PTR_ERR(page);
	goto completion;
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}
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#endif
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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:
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 * for a block special file file->f_path.dentry->d_inode->i_size is zero
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 * 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;

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	mutex_lock(&bd_inode->i_mutex);
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	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;
	}
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	mutex_unlock(&bd_inode->i_mutex);
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	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);
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static struct kmem_cache * bdev_cachep __read_mostly;
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static struct inode *bdev_alloc_inode(struct super_block *sb)
{
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	struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
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	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);
}

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static void init_once(void * foo, struct kmem_cache * cachep, unsigned long flags)
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{
	struct bdev_inode *ei = (struct bdev_inode *) foo;
	struct block_device *bdev = &ei->bdev;

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	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);
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#ifdef CONFIG_SYSFS
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	INIT_LIST_HEAD(&bdev->bd_holder_list);
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#endif
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	inode_init_once(&ei->vfs_inode);
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}

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);
}

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

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static int bd_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
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{
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	return get_sb_pseudo(fs_type, "bdev:", &bdev_sops, 0x62646576, mnt);
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}

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

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static struct vfsmount *bd_mnt __read_mostly;
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struct super_block *blockdev_superblock;

void __init bdev_cache_init(void)
{
	int err;
	bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
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			0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
				SLAB_MEM_SPREAD|SLAB_PANIC),
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			init_once);
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	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)
{
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	struct block_device *bdev;
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	long ret = 0;
	spin_lock(&bdev_lock);
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	list_for_each_entry(bdev, &all_bdevs, bd_list) {
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		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;
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	spin_lock(&bdev_lock);
	bdev = inode->i_bdev;
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	if (bdev) {
		atomic_inc(&bdev->bd_inode->i_count);
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		spin_unlock(&bdev_lock);
		return bdev;
	}
	spin_unlock(&bdev_lock);
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	bdev = bdget(inode->i_rdev);
	if (bdev) {
		spin_lock(&bdev_lock);
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		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);
		}
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		spin_unlock(&bdev_lock);
	}
	return bdev;
}

/* Call when you free inode */

void bd_forget(struct inode *inode)
{
645 646
	struct block_device *bdev = NULL;

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	spin_lock(&bdev_lock);
648 649 650
	if (inode->i_bdev) {
		if (inode->i_sb != blockdev_superblock)
			bdev = inode->i_bdev;
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		__bd_forget(inode);
652
	}
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	spin_unlock(&bdev_lock);
654 655 656

	if (bdev)
		iput(bdev->bd_inode);
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}

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);

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
#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);
}

742
static int add_symlink(struct kobject *from, struct kobject *to)
743 744
{
	if (!from || !to)
745 746
		return 0;
	return sysfs_create_link(from, to, kobject_name(to));
747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837
}

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);
}

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/**
 * 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.
 */
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Andrew Morton 已提交
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static struct bd_holder *find_bd_holder(struct block_device *bdev,
					struct bd_holder *bo)
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{
	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;
}

862 863 864 865 866 867
/**
 * 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()
 *
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 * Add @bo to @bdev->bd_holder_list, create symlinks.
869
 *
J
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 * Returns 0 if symlinks are created.
 * Returns -ve if something fails.
872 873 874
 */
static int add_bd_holder(struct block_device *bdev, struct bd_holder *bo)
{
875
	int err;
876 877

	if (!bo)
878
		return -EINVAL;
879 880

	if (!bd_holder_grab_dirs(bdev, bo))
881
		return -EBUSY;
882

883 884 885 886 887 888 889 890
	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;
891
	}
892 893 894

	list_add_tail(&bo->list, &bdev->bd_holder_list);
	return 0;
895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951
}

/**
 * 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)
{
952
	int err;
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Jun'ichi Nomura 已提交
953
	struct bd_holder *bo, *found;
954 955 956 957 958 959 960 961

	if (!kobj)
		return -EINVAL;

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

962
	mutex_lock(&bdev->bd_mutex);
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Jun'ichi Nomura 已提交
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964 965
	err = bd_claim(bdev, holder);
	if (err)
A
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		goto fail;
967 968 969

	found = find_bd_holder(bdev, bo);
	if (found)
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Andrew Morton 已提交
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		goto fail;
971 972 973 974

	err = add_bd_holder(bdev, bo);
	if (err)
		bd_release(bdev);
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	else
		bo = NULL;
fail:
978
	mutex_unlock(&bdev->bd_mutex);
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	free_bd_holder(bo);
980
	return err;
981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996
}

/**
 * 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;

997
	mutex_lock(&bdev->bd_mutex);
998
	bd_release(bdev);
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Andrew Morton 已提交
999
	free_bd_holder(del_bd_holder(bdev, kobj));
1000
	mutex_unlock(&bdev->bd_mutex);
1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034
}

/**
 * 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

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/*
 * 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;

1073
	if (__invalidate_device(bdev))
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		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);

1100 1101
static int __blkdev_get(struct block_device *bdev, mode_t mode, unsigned flags,
			int for_part);
1102
static int __blkdev_put(struct block_device *bdev, int for_part);
1103

1104 1105 1106 1107 1108 1109 1110
/*
 * bd_mutex locking:
 *
 *  mutex_lock(part->bd_mutex)
 *    mutex_lock_nested(whole->bd_mutex, 1)
 */

1111
static int do_open(struct block_device *bdev, struct file *file, int for_part)
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{
	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;

1128
	mutex_lock_nested(&bdev->bd_mutex, for_part);
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	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;
1155 1156
			BUG_ON(for_part);
			ret = __blkdev_get(whole, file->f_mode, file->f_flags, 1);
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			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++;
1185 1186
	if (for_part)
		bdev->bd_part_count++;
1187
	mutex_unlock(&bdev->bd_mutex);
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	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)
1195
		__blkdev_put(bdev->bd_contains, 1);
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	bdev->bd_contains = NULL;
	put_disk(disk);
	module_put(owner);
out:
1200
	mutex_unlock(&bdev->bd_mutex);
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	unlock_kernel();
	if (ret)
		bdput(bdev);
	return ret;
}

1207 1208
static int __blkdev_get(struct block_device *bdev, mode_t mode, unsigned flags,
			int for_part)
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{
	/*
	 * 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;
1220
	fake_file.f_path.dentry = &fake_dentry;
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	fake_dentry.d_inode = bdev->bd_inode;

1223
	return do_open(bdev, &fake_file, for_part);
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}

1226 1227 1228 1229
int blkdev_get(struct block_device *bdev, mode_t mode, unsigned flags)
{
	return __blkdev_get(bdev, mode, flags, 0);
}
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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);
1246 1247
	if (bdev == NULL)
		return -ENOMEM;
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1249
	res = do_open(bdev, filp, 0);
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	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;
}

1263
static int __blkdev_put(struct block_device *bdev, int for_part)
1264 1265 1266 1267
{
	int ret = 0;
	struct inode *bd_inode = bdev->bd_inode;
	struct gendisk *disk = bdev->bd_disk;
1268
	struct block_device *victim = NULL;
1269

1270
	mutex_lock_nested(&bdev->bd_mutex, for_part);
1271
	lock_kernel();
1272 1273 1274
	if (for_part)
		bdev->bd_part_count--;

1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294
	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;
1295 1296
		if (bdev != bdev->bd_contains)
			victim = bdev->bd_contains;
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		bdev->bd_contains = NULL;
	}
	unlock_kernel();
	mutex_unlock(&bdev->bd_mutex);
	bdput(bdev);
1302 1303
	if (victim)
		__blkdev_put(victim, 1);
1304 1305 1306
	return ret;
}

1307 1308 1309 1310
int blkdev_put(struct block_device *bdev)
{
	return __blkdev_put(bdev, 0);
}
1311 1312
EXPORT_SYMBOL(blkdev_put);

L
Linus Torvalds 已提交
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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);
}

1321
static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
L
Linus Torvalds 已提交
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{
	return blkdev_ioctl(file->f_mapping->host, file, cmd, arg);
}

1326
const struct address_space_operations def_blk_aops = {
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Linus Torvalds 已提交
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	.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,
};

1336
const struct file_operations def_blk_fops = {
L
Linus Torvalds 已提交
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	.open		= blkdev_open,
	.release	= blkdev_close,
	.llseek		= block_llseek,
1340 1341
	.read		= do_sync_read,
	.write		= do_sync_write,
L
Linus Torvalds 已提交
1342
  	.aio_read	= generic_file_aio_read,
1343
  	.aio_write	= generic_file_aio_write_nolock,
L
Linus Torvalds 已提交
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	.mmap		= generic_file_mmap,
	.fsync		= block_fsync,
1346
	.unlocked_ioctl	= block_ioctl,
L
Linus Torvalds 已提交
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#ifdef CONFIG_COMPAT
	.compat_ioctl	= compat_blkdev_ioctl,
#endif
1350 1351
	.splice_read	= generic_file_splice_read,
	.splice_write	= generic_file_splice_write,
L
Linus Torvalds 已提交
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};

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);
1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479

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);
	}
1480
	invalidate_bdev(bdev);
1481 1482 1483
	return res;
}
EXPORT_SYMBOL(__invalidate_device);