block_dev.c 42.6 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>
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#include <linux/device_cgroup.h>
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#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/pagevec.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 <linux/kmemleak.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;
};

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static const struct address_space_operations def_blk_aops;

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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 */
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	if (size < bdev_logical_block_size(bdev))
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		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)
{
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	int minsize = bdev_logical_block_size(sb->s_bdev);
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	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;

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	return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset,
				    nr_segs, blkdev_get_blocks, NULL, NULL, 0);
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}

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int __sync_blockdev(struct block_device *bdev, int wait)
{
	if (!bdev)
		return 0;
	if (!wait)
		return filemap_flush(bdev->bd_inode->i_mapping);
	return filemap_write_and_wait(bdev->bd_inode->i_mapping);
}

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/*
 * Write out and wait upon all the dirty data associated with a block
 * device via its mapping.  Does not take the superblock lock.
 */
int sync_blockdev(struct block_device *bdev)
{
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	return __sync_blockdev(bdev, 1);
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}
EXPORT_SYMBOL(sync_blockdev);

/*
 * Write out and wait upon all dirty data associated with this
 * device.   Filesystem data as well as the underlying block
 * device.  Takes the superblock lock.
 */
int fsync_bdev(struct block_device *bdev)
{
	struct super_block *sb = get_super(bdev);
	if (sb) {
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		int res = sync_filesystem(sb);
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		drop_super(sb);
		return res;
	}
	return sync_blockdev(bdev);
}
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EXPORT_SYMBOL(fsync_bdev);
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/**
 * freeze_bdev  --  lock a filesystem and force it into a consistent state
 * @bdev:	blockdevice to lock
 *
 * If a superblock is found on this device, we take the s_umount semaphore
 * on it to make sure nobody unmounts until the snapshot creation is done.
 * The reference counter (bd_fsfreeze_count) guarantees that only the last
 * unfreeze process can unfreeze the frozen filesystem actually when multiple
 * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
 * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
 * actually.
 */
struct super_block *freeze_bdev(struct block_device *bdev)
{
	struct super_block *sb;
	int error = 0;

	mutex_lock(&bdev->bd_fsfreeze_mutex);
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	if (++bdev->bd_fsfreeze_count > 1) {
		/*
		 * We don't even need to grab a reference - the first call
		 * to freeze_bdev grab an active reference and only the last
		 * thaw_bdev drops it.
		 */
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		sb = get_super(bdev);
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		drop_super(sb);
		mutex_unlock(&bdev->bd_fsfreeze_mutex);
		return sb;
	}

	sb = get_active_super(bdev);
	if (!sb)
		goto out;
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	error = freeze_super(sb);
	if (error) {
		deactivate_super(sb);
		bdev->bd_fsfreeze_count--;
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		mutex_unlock(&bdev->bd_fsfreeze_mutex);
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		return ERR_PTR(error);
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	}
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	deactivate_super(sb);
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 out:
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	sync_blockdev(bdev);
	mutex_unlock(&bdev->bd_fsfreeze_mutex);
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	return sb;	/* thaw_bdev releases s->s_umount */
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}
EXPORT_SYMBOL(freeze_bdev);

/**
 * thaw_bdev  -- unlock filesystem
 * @bdev:	blockdevice to unlock
 * @sb:		associated superblock
 *
 * Unlocks the filesystem and marks it writeable again after freeze_bdev().
 */
int thaw_bdev(struct block_device *bdev, struct super_block *sb)
{
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	int error = -EINVAL;
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	mutex_lock(&bdev->bd_fsfreeze_mutex);
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	if (!bdev->bd_fsfreeze_count)
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		goto out;
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	error = 0;
	if (--bdev->bd_fsfreeze_count > 0)
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		goto out;
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	if (!sb)
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		goto out;
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	error = thaw_super(sb);
	if (error) {
		bdev->bd_fsfreeze_count++;
		mutex_unlock(&bdev->bd_fsfreeze_mutex);
		return error;
	}
out:
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	mutex_unlock(&bdev->bd_fsfreeze_mutex);
	return 0;
}
EXPORT_SYMBOL(thaw_bdev);

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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);
}

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static int blkdev_write_begin(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned flags,
			struct page **pagep, void **fsdata)
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{
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	*pagep = NULL;
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	return block_write_begin_newtrunc(file, mapping, pos, len, flags,
				pagep, fsdata, blkdev_get_block);
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}

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static int blkdev_write_end(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned copied,
			struct page *page, void *fsdata)
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{
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	int ret;
	ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);

	unlock_page(page);
	page_cache_release(page);

	return ret;
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}

/*
 * 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;
}
	
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int blkdev_fsync(struct file *filp, int datasync)
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{
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	struct inode *bd_inode = filp->f_mapping->host;
	struct block_device *bdev = I_BDEV(bd_inode);
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	int error;

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	/*
	 * There is no need to serialise calls to blkdev_issue_flush with
	 * i_mutex and doing so causes performance issues with concurrent
	 * O_SYNC writers to a block device.
	 */
	mutex_unlock(&bd_inode->i_mutex);

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	error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL, BLKDEV_IFL_WAIT);
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	if (error == -EOPNOTSUPP)
		error = 0;
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	mutex_lock(&bd_inode->i_mutex);

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	return error;
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}
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EXPORT_SYMBOL(blkdev_fsync);
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/*
 * 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);

	kmem_cache_free(bdev_cachep, bdi);
}

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static void init_once(void *foo)
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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);
	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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	/* Initialize mutex for freeze. */
	mutex_init(&bdev->bd_fsfreeze_mutex);
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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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struct super_block *blockdev_superblock __read_mostly;
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void __init bdev_cache_init(void)
{
	int err;
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	struct vfsmount *bd_mnt;

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	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);
	if (IS_ERR(bd_mnt))
		panic("Cannot create bdev pseudo-fs");
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	/*
	 * This vfsmount structure is only used to obtain the
	 * blockdev_superblock, so tell kmemleak not to report it.
	 */
	kmemleak_not_leak(bd_mnt);
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	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;

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	inode = iget5_locked(blockdev_superblock, hash(dev),
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			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);

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/**
 * bdgrab -- Grab a reference to an already referenced block device
 * @bdev:	Block device to grab a reference to.
 */
struct block_device *bdgrab(struct block_device *bdev)
{
	atomic_inc(&bdev->bd_inode->i_count);
	return bdev;
}

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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)
{
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	struct block_device *bdev = NULL;

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	spin_lock(&bdev_lock);
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	if (inode->i_bdev) {
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		if (!sb_is_blkdev_sb(inode->i_sb))
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			bdev = inode->i_bdev;
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		__bd_forget(inode);
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	}
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	spin_unlock(&bdev_lock);
620 621 622

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

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/**
 * bd_may_claim - test whether a block device can be claimed
 * @bdev: block device of interest
 * @whole: whole block device containing @bdev, may equal @bdev
 * @holder: holder trying to claim @bdev
 *
 * Test whther @bdev can be claimed by @holder.
 *
 * CONTEXT:
 * spin_lock(&bdev_lock).
 *
 * RETURNS:
 * %true if @bdev can be claimed, %false otherwise.
 */
static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
			 void *holder)
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{
	if (bdev->bd_holder == holder)
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		return true;	 /* already a holder */
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	else if (bdev->bd_holder != NULL)
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		return false; 	 /* held by someone else */
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	else if (bdev->bd_contains == bdev)
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		return true;  	 /* is a whole device which isn't held */
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	else if (whole->bd_holder == bd_claim)
		return true; 	 /* is a partition of a device that is being partitioned */
	else if (whole->bd_holder != NULL)
		return false;	 /* is a partition of a held device */
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	else
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		return true;	 /* is a partition of an un-held device */
}

657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707
/**
 * bd_prepare_to_claim - prepare to claim a block device
 * @bdev: block device of interest
 * @whole: the whole device containing @bdev, may equal @bdev
 * @holder: holder trying to claim @bdev
 *
 * Prepare to claim @bdev.  This function fails if @bdev is already
 * claimed by another holder and waits if another claiming is in
 * progress.  This function doesn't actually claim.  On successful
 * return, the caller has ownership of bd_claiming and bd_holder[s].
 *
 * CONTEXT:
 * spin_lock(&bdev_lock).  Might release bdev_lock, sleep and regrab
 * it multiple times.
 *
 * RETURNS:
 * 0 if @bdev can be claimed, -EBUSY otherwise.
 */
static int bd_prepare_to_claim(struct block_device *bdev,
			       struct block_device *whole, void *holder)
{
retry:
	/* if someone else claimed, fail */
	if (!bd_may_claim(bdev, whole, holder))
		return -EBUSY;

	/* if someone else is claiming, wait for it to finish */
	if (whole->bd_claiming && whole->bd_claiming != holder) {
		wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
		DEFINE_WAIT(wait);

		prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
		spin_unlock(&bdev_lock);
		schedule();
		finish_wait(wq, &wait);
		spin_lock(&bdev_lock);
		goto retry;
	}

	/* yay, all mine */
	return 0;
}

/**
 * bd_start_claiming - start claiming a block device
 * @bdev: block device of interest
 * @holder: holder trying to claim @bdev
 *
 * @bdev is about to be opened exclusively.  Check @bdev can be opened
 * exclusively and mark that an exclusive open is in progress.  Each
 * successful call to this function must be matched with a call to
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 * either bd_finish_claiming() or bd_abort_claiming() (which do not
 * fail).
 *
 * This function is used to gain exclusive access to the block device
 * without actually causing other exclusive open attempts to fail. It
 * should be used when the open sequence itself requires exclusive
 * access but may subsequently fail.
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
 *
 * CONTEXT:
 * Might sleep.
 *
 * RETURNS:
 * Pointer to the block device containing @bdev on success, ERR_PTR()
 * value on failure.
 */
static struct block_device *bd_start_claiming(struct block_device *bdev,
					      void *holder)
{
	struct gendisk *disk;
	struct block_device *whole;
	int partno, err;

	might_sleep();

	/*
	 * @bdev might not have been initialized properly yet, look up
	 * and grab the outer block device the hard way.
	 */
	disk = get_gendisk(bdev->bd_dev, &partno);
	if (!disk)
		return ERR_PTR(-ENXIO);

	whole = bdget_disk(disk, 0);
741
	module_put(disk->fops->owner);
742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789
	put_disk(disk);
	if (!whole)
		return ERR_PTR(-ENOMEM);

	/* prepare to claim, if successful, mark claiming in progress */
	spin_lock(&bdev_lock);

	err = bd_prepare_to_claim(bdev, whole, holder);
	if (err == 0) {
		whole->bd_claiming = holder;
		spin_unlock(&bdev_lock);
		return whole;
	} else {
		spin_unlock(&bdev_lock);
		bdput(whole);
		return ERR_PTR(err);
	}
}

/* releases bdev_lock */
static void __bd_abort_claiming(struct block_device *whole, void *holder)
{
	BUG_ON(whole->bd_claiming != holder);
	whole->bd_claiming = NULL;
	wake_up_bit(&whole->bd_claiming, 0);

	spin_unlock(&bdev_lock);
	bdput(whole);
}

/**
 * bd_abort_claiming - abort claiming a block device
 * @whole: whole block device returned by bd_start_claiming()
 * @holder: holder trying to claim @bdev
 *
 * Abort a claiming block started by bd_start_claiming().  Note that
 * @whole is not the block device to be claimed but the whole device
 * returned by bd_start_claiming().
 *
 * CONTEXT:
 * Grabs and releases bdev_lock.
 */
static void bd_abort_claiming(struct block_device *whole, void *holder)
{
	spin_lock(&bdev_lock);
	__bd_abort_claiming(whole, holder);		/* releases bdev_lock */
}

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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
/* increment holders when we have a legitimate claim. requires bdev_lock */
static void __bd_claim(struct block_device *bdev, struct block_device *whole,
					void *holder)
{
	/* 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
	 */
	whole->bd_holders++;
	whole->bd_holder = bd_claim;
	bdev->bd_holders++;
	bdev->bd_holder = holder;
}

/**
 * bd_finish_claiming - finish claiming a block device
 * @bdev: block device of interest (passed to bd_start_claiming())
 * @whole: whole block device returned by bd_start_claiming()
 * @holder: holder trying to claim @bdev
 *
 * Finish a claiming block started by bd_start_claiming().
 *
 * CONTEXT:
 * Grabs and releases bdev_lock.
 */
static void bd_finish_claiming(struct block_device *bdev,
				struct block_device *whole, void *holder)
{
	spin_lock(&bdev_lock);
	BUG_ON(!bd_may_claim(bdev, whole, holder));
	__bd_claim(bdev, whole, holder);
	__bd_abort_claiming(whole, holder); /* not actually an abort */
}

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824 825 826 827 828
/**
 * bd_claim - claim a block device
 * @bdev: block device to claim
 * @holder: holder trying to claim @bdev
 *
N
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 * Try to claim @bdev which must have been opened successfully.
830 831 832
 *
 * CONTEXT:
 * Might sleep.
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 *
 * RETURNS:
 * 0 if successful, -EBUSY if @bdev is already claimed.
 */
int bd_claim(struct block_device *bdev, void *holder)
{
	struct block_device *whole = bdev->bd_contains;
840 841 842
	int res;

	might_sleep();
T
Tejun Heo 已提交
843 844

	spin_lock(&bdev_lock);
845
	res = bd_prepare_to_claim(bdev, whole, holder);
N
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846 847 848
	if (res == 0)
		__bd_claim(bdev, whole, holder);
	spin_unlock(&bdev_lock);
849

L
Linus Torvalds 已提交
850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865
	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);

866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883
#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
 */

884
static int add_symlink(struct kobject *from, struct kobject *to)
885 886
{
	if (!from || !to)
887 888
		return 0;
	return sysfs_create_link(from, to, kobject_name(to));
889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931
}

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;

T
Tejun Heo 已提交
932
	bo->sdev = kobject_get(&part_to_dev(bdev->bd_part)->kobj);
933 934 935
	if (!bo->sdev)
		goto fail_put_hdev;

936
	bo->hdir = kobject_get(bdev->bd_part->holder_dir);
937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979
	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
980 981 982 983 984 985 986 987 988 989
/**
 * 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
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990 991
static struct bd_holder *find_bd_holder(struct block_device *bdev,
					struct bd_holder *bo)
J
Jun'ichi Nomura 已提交
992 993 994 995 996 997 998 999 1000 1001 1002 1003
{
	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;
}

1004 1005 1006 1007 1008 1009
/**
 * 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
1010
 * Add @bo to @bdev->bd_holder_list, create symlinks.
1011
 *
J
Jun'ichi Nomura 已提交
1012 1013
 * Returns 0 if symlinks are created.
 * Returns -ve if something fails.
1014 1015 1016
 */
static int add_bd_holder(struct block_device *bdev, struct bd_holder *bo)
{
1017
	int err;
1018 1019

	if (!bo)
1020
		return -EINVAL;
1021 1022

	if (!bd_holder_grab_dirs(bdev, bo))
1023
		return -EBUSY;
1024

1025 1026 1027 1028 1029 1030 1031 1032
	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;
1033
	}
1034 1035 1036

	list_add_tail(&bo->list, &bdev->bd_holder_list);
	return 0;
1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093
}

/**
 * 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)
{
1094
	int err;
J
Jun'ichi Nomura 已提交
1095
	struct bd_holder *bo, *found;
1096 1097 1098 1099 1100 1101 1102 1103

	if (!kobj)
		return -EINVAL;

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

1104
	mutex_lock(&bdev->bd_mutex);
J
Jun'ichi Nomura 已提交
1105

1106 1107
	err = bd_claim(bdev, holder);
	if (err)
A
Andrew Morton 已提交
1108
		goto fail;
1109 1110 1111

	found = find_bd_holder(bdev, bo);
	if (found)
A
Andrew Morton 已提交
1112
		goto fail;
1113 1114 1115 1116

	err = add_bd_holder(bdev, bo);
	if (err)
		bd_release(bdev);
A
Andrew Morton 已提交
1117 1118 1119
	else
		bo = NULL;
fail:
1120
	mutex_unlock(&bdev->bd_mutex);
A
Andrew Morton 已提交
1121
	free_bd_holder(bo);
1122
	return err;
1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138
}

/**
 * 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;

1139
	mutex_lock(&bdev->bd_mutex);
1140
	bd_release(bdev);
A
Andrew Morton 已提交
1141
	free_bd_holder(del_bd_holder(bdev, kobj));
1142
	mutex_unlock(&bdev->bd_mutex);
1143 1144 1145 1146 1147 1148 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
}

/**
 * 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
1177 1178 1179 1180 1181 1182 1183
/*
 * 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.
 */
1184
struct block_device *open_by_devnum(dev_t dev, fmode_t mode)
L
Linus Torvalds 已提交
1185 1186 1187 1188
{
	struct block_device *bdev = bdget(dev);
	int err = -ENOMEM;
	if (bdev)
1189
		err = blkdev_get(bdev, mode);
L
Linus Torvalds 已提交
1190 1191 1192 1193 1194
	return err ? ERR_PTR(err) : bdev;
}

EXPORT_SYMBOL(open_by_devnum);

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
/**
 * 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;
}

1221
/**
1222
 * check_disk_size_change - checks for disk size change and adjusts bdev size.
1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242
 * @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);
1243
		flush_disk(bdev);
1244 1245 1246 1247
	}
}
EXPORT_SYMBOL(check_disk_size_change);

1248
/**
1249
 * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
1250 1251 1252 1253 1254 1255 1256 1257
 * @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)
{
1258
	struct block_device *bdev;
1259 1260 1261 1262 1263
	int ret = 0;

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

1264 1265 1266 1267 1268 1269 1270 1271
	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);
1272 1273 1274 1275
	return ret;
}
EXPORT_SYMBOL(revalidate_disk);

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/*
 * 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;
1288
	const struct block_device_operations *bdops = disk->fops;
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	if (!bdops->media_changed)
		return 0;
	if (!bdops->media_changed(bdev->bd_disk))
		return 0;

1295
	flush_disk(bdev);
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	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)
{
1305
	unsigned bsize = bdev_logical_block_size(bdev);
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	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);

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static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
1319

1320 1321 1322 1323 1324 1325 1326
/*
 * bd_mutex locking:
 *
 *  mutex_lock(part->bd_mutex)
 *    mutex_lock_nested(whole->bd_mutex, 1)
 */

1327
static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
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{
	struct gendisk *disk;
1330
	int ret;
1331
	int partno;
1332 1333
	int perm = 0;

1334
	if (mode & FMODE_READ)
1335
		perm |= MAY_READ;
1336
	if (mode & FMODE_WRITE)
1337 1338 1339 1340 1341
		perm |= MAY_WRITE;
	/*
	 * hooks: /n/, see "layering violations".
	 */
	ret = devcgroup_inode_permission(bdev->bd_inode, perm);
1342 1343
	if (ret != 0) {
		bdput(bdev);
1344
		return ret;
1345
	}
1346

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	lock_kernel();
1348
 restart:
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1350
	ret = -ENXIO;
1351
	disk = get_gendisk(bdev->bd_dev, &partno);
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	if (!disk)
		goto out_unlock_kernel;
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1354

1355
	mutex_lock_nested(&bdev->bd_mutex, for_part);
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	if (!bdev->bd_openers) {
		bdev->bd_disk = disk;
		bdev->bd_contains = bdev;
1359
		if (!partno) {
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			struct backing_dev_info *bdi;
1361 1362 1363 1364 1365 1366

			ret = -ENXIO;
			bdev->bd_part = disk_get_part(disk, partno);
			if (!bdev->bd_part)
				goto out_clear;

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			if (disk->fops->open) {
1368
				ret = disk->fops->open(bdev, mode);
1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381
				if (ret == -ERESTARTSYS) {
					/* Lost a race with 'disk' being
					 * deleted, try again.
					 * See md.c
					 */
					disk_put_part(bdev->bd_part);
					bdev->bd_part = NULL;
					module_put(disk->fops->owner);
					put_disk(disk);
					bdev->bd_disk = NULL;
					mutex_unlock(&bdev->bd_mutex);
					goto restart;
				}
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				if (ret)
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					goto out_clear;
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			}
			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)
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				goto out_clear;
1400
			BUG_ON(for_part);
1401
			ret = __blkdev_get(whole, mode, 1);
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1402
			if (ret)
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				goto out_clear;
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			bdev->bd_contains = whole;
			bdev->bd_inode->i_data.backing_dev_info =
			   whole->bd_inode->i_data.backing_dev_info;
1407
			bdev->bd_part = disk_get_part(disk, partno);
1408
			if (!(disk->flags & GENHD_FL_UP) ||
1409
			    !bdev->bd_part || !bdev->bd_part->nr_sects) {
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				ret = -ENXIO;
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1411
				goto out_clear;
L
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1412
			}
1413
			bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
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1414 1415
		}
	} else {
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1416
		module_put(disk->fops->owner);
1417
		put_disk(disk);
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1418
		disk = NULL;
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1419 1420
		if (bdev->bd_contains == bdev) {
			if (bdev->bd_disk->fops->open) {
1421
				ret = bdev->bd_disk->fops->open(bdev, mode);
L
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1422
				if (ret)
T
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1423
					goto out_unlock_bdev;
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1424 1425 1426 1427 1428 1429
			}
			if (bdev->bd_invalidated)
				rescan_partitions(bdev->bd_disk, bdev);
		}
	}
	bdev->bd_openers++;
1430 1431
	if (for_part)
		bdev->bd_part_count++;
1432
	mutex_unlock(&bdev->bd_mutex);
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1433 1434 1435
	unlock_kernel();
	return 0;

T
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 out_clear:
1437
	disk_put_part(bdev->bd_part);
L
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1438
	bdev->bd_disk = NULL;
T
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1439
	bdev->bd_part = NULL;
L
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1440 1441
	bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
	if (bdev != bdev->bd_contains)
1442
		__blkdev_put(bdev->bd_contains, mode, 1);
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1443
	bdev->bd_contains = NULL;
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1444
 out_unlock_bdev:
1445
	mutex_unlock(&bdev->bd_mutex);
T
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1446
 out_unlock_kernel:
L
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1447
	unlock_kernel();
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1448 1449 1450 1451 1452 1453

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

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	return ret;
}

1457
int blkdev_get(struct block_device *bdev, fmode_t mode)
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1458
{
1459
	return __blkdev_get(bdev, mode, 0);
1460
}
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EXPORT_SYMBOL(blkdev_get);

static int blkdev_open(struct inode * inode, struct file * filp)
{
1465
	struct block_device *whole = NULL;
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1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476
	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;

1477 1478 1479 1480 1481 1482 1483
	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;

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	bdev = bd_acquire(inode);
1485 1486
	if (bdev == NULL)
		return -ENOMEM;
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1487

1488 1489 1490 1491 1492 1493 1494 1495
	if (filp->f_mode & FMODE_EXCL) {
		whole = bd_start_claiming(bdev, filp);
		if (IS_ERR(whole)) {
			bdput(bdev);
			return PTR_ERR(whole);
		}
	}

1496 1497 1498
	filp->f_mapping = bdev->bd_inode->i_mapping;

	res = blkdev_get(bdev, filp->f_mode);
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1500 1501
	if (whole) {
		if (res == 0)
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Nick Piggin 已提交
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			bd_finish_claiming(bdev, whole, filp);
1503 1504
		else
			bd_abort_claiming(whole, filp);
1505
	}
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1506 1507 1508 1509

	return res;
}

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1510
static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
1511 1512 1513
{
	int ret = 0;
	struct gendisk *disk = bdev->bd_disk;
1514
	struct block_device *victim = NULL;
1515

1516
	mutex_lock_nested(&bdev->bd_mutex, for_part);
1517
	lock_kernel();
1518 1519 1520
	if (for_part)
		bdev->bd_part_count--;

1521 1522 1523 1524 1525 1526
	if (!--bdev->bd_openers) {
		sync_blockdev(bdev);
		kill_bdev(bdev);
	}
	if (bdev->bd_contains == bdev) {
		if (disk->fops->release)
A
Al Viro 已提交
1527
			ret = disk->fops->release(disk, mode);
1528 1529 1530 1531 1532 1533
	}
	if (!bdev->bd_openers) {
		struct module *owner = disk->fops->owner;

		put_disk(disk);
		module_put(owner);
T
Tejun Heo 已提交
1534 1535
		disk_put_part(bdev->bd_part);
		bdev->bd_part = NULL;
1536 1537
		bdev->bd_disk = NULL;
		bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
1538 1539
		if (bdev != bdev->bd_contains)
			victim = bdev->bd_contains;
1540 1541 1542 1543 1544
		bdev->bd_contains = NULL;
	}
	unlock_kernel();
	mutex_unlock(&bdev->bd_mutex);
	bdput(bdev);
1545
	if (victim)
A
Al Viro 已提交
1546
		__blkdev_put(victim, mode, 1);
1547 1548 1549
	return ret;
}

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Al Viro 已提交
1550
int blkdev_put(struct block_device *bdev, fmode_t mode)
1551
{
A
Al Viro 已提交
1552
	return __blkdev_put(bdev, mode, 0);
1553
}
1554 1555
EXPORT_SYMBOL(blkdev_put);

L
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1556 1557 1558 1559 1560
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);
A
Al Viro 已提交
1561
	return blkdev_put(bdev, filp->f_mode);
L
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1562 1563
}

1564
static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
L
Linus Torvalds 已提交
1565
{
1566 1567
	struct block_device *bdev = I_BDEV(file->f_mapping->host);
	fmode_t mode = file->f_mode;
1568 1569 1570 1571 1572

	/*
	 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
	 * to updated it before every ioctl.
	 */
1573
	if (file->f_flags & O_NDELAY)
1574 1575 1576 1577
		mode |= FMODE_NDELAY;
	else
		mode &= ~FMODE_NDELAY;

1578
	return blkdev_ioctl(bdev, mode, cmd, arg);
L
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1579 1580
}

1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607
/*
 * Write data to the block device.  Only intended for the block device itself
 * and the raw driver which basically is a fake block device.
 *
 * Does not take i_mutex for the write and thus is not for general purpose
 * use.
 */
ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
			 unsigned long nr_segs, loff_t pos)
{
	struct file *file = iocb->ki_filp;
	ssize_t ret;

	BUG_ON(iocb->ki_pos != pos);

	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
	if (ret > 0 || ret == -EIOCBQUEUED) {
		ssize_t err;

		err = generic_write_sync(file, pos, ret);
		if (err < 0 && ret > 0)
			ret = err;
	}
	return ret;
}
EXPORT_SYMBOL_GPL(blkdev_aio_write);

1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621
/*
 * Try to release a page associated with block device when the system
 * is under memory pressure.
 */
static int blkdev_releasepage(struct page *page, gfp_t wait)
{
	struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;

	if (super && super->s_op->bdev_try_to_free_page)
		return super->s_op->bdev_try_to_free_page(super, page, wait);

	return try_to_free_buffers(page);
}

A
Adrian Bunk 已提交
1622
static const struct address_space_operations def_blk_aops = {
L
Linus Torvalds 已提交
1623 1624 1625
	.readpage	= blkdev_readpage,
	.writepage	= blkdev_writepage,
	.sync_page	= block_sync_page,
N
Nick Piggin 已提交
1626 1627
	.write_begin	= blkdev_write_begin,
	.write_end	= blkdev_write_end,
L
Linus Torvalds 已提交
1628
	.writepages	= generic_writepages,
1629
	.releasepage	= blkdev_releasepage,
L
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1630 1631 1632
	.direct_IO	= blkdev_direct_IO,
};

1633
const struct file_operations def_blk_fops = {
L
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1634 1635 1636
	.open		= blkdev_open,
	.release	= blkdev_close,
	.llseek		= block_llseek,
1637 1638
	.read		= do_sync_read,
	.write		= do_sync_write,
L
Linus Torvalds 已提交
1639
  	.aio_read	= generic_file_aio_read,
1640
	.aio_write	= blkdev_aio_write,
L
Linus Torvalds 已提交
1641
	.mmap		= generic_file_mmap,
1642
	.fsync		= blkdev_fsync,
1643
	.unlocked_ioctl	= block_ioctl,
L
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1644 1645 1646
#ifdef CONFIG_COMPAT
	.compat_ioctl	= compat_blkdev_ioctl,
#endif
1647 1648
	.splice_read	= generic_file_splice_read,
	.splice_write	= generic_file_splice_write,
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1649 1650 1651 1652 1653 1654 1655
};

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);
1656
	res = blkdev_ioctl(bdev, 0, cmd, arg);
L
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1657 1658 1659 1660 1661 1662 1663 1664
	set_fs(old_fs);
	return res;
}

EXPORT_SYMBOL(ioctl_by_bdev);

/**
 * lookup_bdev  - lookup a struct block_device by name
1665
 * @pathname:	special file representing the block device
L
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1666
 *
1667
 * Get a reference to the blockdevice at @pathname in the current
L
Linus Torvalds 已提交
1668 1669 1670
 * namespace if possible and return it.  Return ERR_PTR(error)
 * otherwise.
 */
1671
struct block_device *lookup_bdev(const char *pathname)
L
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1672 1673 1674
{
	struct block_device *bdev;
	struct inode *inode;
1675
	struct path path;
L
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1676 1677
	int error;

1678
	if (!pathname || !*pathname)
L
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1679 1680
		return ERR_PTR(-EINVAL);

1681
	error = kern_path(pathname, LOOKUP_FOLLOW, &path);
L
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1682 1683 1684
	if (error)
		return ERR_PTR(error);

1685
	inode = path.dentry->d_inode;
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1686 1687 1688 1689
	error = -ENOTBLK;
	if (!S_ISBLK(inode->i_mode))
		goto fail;
	error = -EACCES;
1690
	if (path.mnt->mnt_flags & MNT_NODEV)
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1691 1692 1693 1694 1695 1696
		goto fail;
	error = -ENOMEM;
	bdev = bd_acquire(inode);
	if (!bdev)
		goto fail;
out:
1697
	path_put(&path);
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1698 1699 1700 1701 1702
	return bdev;
fail:
	bdev = ERR_PTR(error);
	goto out;
}
1703
EXPORT_SYMBOL(lookup_bdev);
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1704 1705

/**
1706
 * open_bdev_exclusive  -  open a block device by name and set it up for use
L
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1707 1708
 *
 * @path:	special file representing the block device
1709
 * @mode:	FMODE_... combination to pass be used
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1710 1711 1712 1713 1714
 * @holder:	owner for exclusion
 *
 * Open the blockdevice described by the special file at @path, claim it
 * for the @holder.
 */
1715
struct block_device *open_bdev_exclusive(const char *path, fmode_t mode, void *holder)
L
Linus Torvalds 已提交
1716
{
1717 1718
	struct block_device *bdev, *whole;
	int error;
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1719 1720 1721 1722 1723

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

1724 1725 1726 1727 1728 1729
	whole = bd_start_claiming(bdev, holder);
	if (IS_ERR(whole)) {
		bdput(bdev);
		return whole;
	}

1730
	error = blkdev_get(bdev, mode);
L
Linus Torvalds 已提交
1731
	if (error)
1732 1733
		goto out_abort_claiming;

L
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1734
	error = -EACCES;
1735
	if ((mode & FMODE_WRITE) && bdev_read_only(bdev))
1736
		goto out_blkdev_put;
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1737

N
Nick Piggin 已提交
1738
	bd_finish_claiming(bdev, whole, holder);
L
Linus Torvalds 已提交
1739
	return bdev;
1740 1741

out_blkdev_put:
A
Al Viro 已提交
1742
	blkdev_put(bdev, mode);
1743 1744
out_abort_claiming:
	bd_abort_claiming(whole, holder);
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1745 1746 1747
	return ERR_PTR(error);
}

1748
EXPORT_SYMBOL(open_bdev_exclusive);
L
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1749 1750

/**
1751
 * close_bdev_exclusive  -  close a blockdevice opened by open_bdev_exclusive()
L
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1752 1753
 *
 * @bdev:	blockdevice to close
1754
 * @mode:	mode, must match that used to open.
L
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1755
 *
1756
 * This is the counterpart to open_bdev_exclusive().
L
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1757
 */
1758
void close_bdev_exclusive(struct block_device *bdev, fmode_t mode)
L
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1759 1760
{
	bd_release(bdev);
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	blkdev_put(bdev, mode);
L
Linus Torvalds 已提交
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}

1764
EXPORT_SYMBOL(close_bdev_exclusive);
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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);
	}
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	invalidate_bdev(bdev);
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	return res;
}
EXPORT_SYMBOL(__invalidate_device);