block_dev.c 44.0 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>
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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>
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#include <linux/magic.h>
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#include <linux/buffer_head.h>
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#include <linux/swap.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/cleancache.h>
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#include <linux/aio.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);

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/*
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 * Move the inode from its current bdi to a new bdi.  Make sure the inode
 * is clean before moving so that it doesn't linger on the old bdi.
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 */
static void bdev_inode_switch_bdi(struct inode *inode,
			struct backing_dev_info *dst)
{
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	while (true) {
		spin_lock(&inode->i_lock);
		if (!(inode->i_state & I_DIRTY)) {
			inode->i_data.backing_dev_info = dst;
			spin_unlock(&inode->i_lock);
			return;
		}
		spin_unlock(&inode->i_lock);
		WARN_ON_ONCE(write_inode_now(inode, true));
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	}
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}

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/* Kill _all_ buffers and pagecache , dirty or not.. */
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void kill_bdev(struct block_device *bdev)
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{
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	struct address_space *mapping = bdev->bd_inode->i_mapping;

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	if (mapping->nrpages == 0 && mapping->nrshadows == 0)
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		return;
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	invalidate_bh_lrus();
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	truncate_inode_pages(mapping, 0);
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}	
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EXPORT_SYMBOL(kill_bdev);

/* Invalidate clean unused buffers and pagecache. */
void invalidate_bdev(struct block_device *bdev)
{
	struct address_space *mapping = bdev->bd_inode->i_mapping;

	if (mapping->nrpages == 0)
		return;

	invalidate_bh_lrus();
	lru_add_drain_all();	/* make sure all lru add caches are flushed */
	invalidate_mapping_pages(mapping, 0, -1);
	/* 99% of the time, we don't need to flush the cleancache on the bdev.
	 * But, for the strange corners, lets be cautious
	 */
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	cleancache_invalidate_inode(mapping);
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}
EXPORT_SYMBOL(invalidate_bdev);
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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)
{
	bh->b_bdev = I_BDEV(inode);
	bh->b_blocknr = iblock;
	set_buffer_mapped(bh);
	return 0;
}

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static ssize_t
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blkdev_direct_IO(int rw, struct kiocb *iocb, struct iov_iter *iter,
			loff_t offset)
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{
	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), iter,
				    offset, blkdev_get_block,
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				    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_readpages(struct file *file, struct address_space *mapping,
			struct list_head *pages, unsigned nr_pages)
{
	return mpage_readpages(mapping, pages, nr_pages, 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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	return block_write_begin(mapping, pos, len, flags, pagep,
				 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_inode(file)->i_size is zero
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 * so we compute the size by hand (just as in block_read/write above)
 */
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static loff_t block_llseek(struct file *file, loff_t offset, int whence)
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{
	struct inode *bd_inode = file->f_mapping->host;
	loff_t retval;

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	mutex_lock(&bd_inode->i_mutex);
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	retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
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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, loff_t start, loff_t end, 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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	error = filemap_write_and_wait_range(filp->f_mapping, start, end);
	if (error)
		return 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.
	 */
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	error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL);
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	if (error == -EOPNOTSUPP)
		error = 0;
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	return error;
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}
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EXPORT_SYMBOL(blkdev_fsync);
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/**
 * bdev_read_page() - Start reading a page from a block device
 * @bdev: The device to read the page from
 * @sector: The offset on the device to read the page to (need not be aligned)
 * @page: The page to read
 *
 * On entry, the page should be locked.  It will be unlocked when the page
 * has been read.  If the block driver implements rw_page synchronously,
 * that will be true on exit from this function, but it need not be.
 *
 * Errors returned by this function are usually "soft", eg out of memory, or
 * queue full; callers should try a different route to read this page rather
 * than propagate an error back up the stack.
 *
 * Return: negative errno if an error occurs, 0 if submission was successful.
 */
int bdev_read_page(struct block_device *bdev, sector_t sector,
			struct page *page)
{
	const struct block_device_operations *ops = bdev->bd_disk->fops;
	if (!ops->rw_page)
		return -EOPNOTSUPP;
	return ops->rw_page(bdev, sector + get_start_sect(bdev), page, READ);
}
EXPORT_SYMBOL_GPL(bdev_read_page);

/**
 * bdev_write_page() - Start writing a page to a block device
 * @bdev: The device to write the page to
 * @sector: The offset on the device to write the page to (need not be aligned)
 * @page: The page to write
 * @wbc: The writeback_control for the write
 *
 * On entry, the page should be locked and not currently under writeback.
 * On exit, if the write started successfully, the page will be unlocked and
 * under writeback.  If the write failed already (eg the driver failed to
 * queue the page to the device), the page will still be locked.  If the
 * caller is a ->writepage implementation, it will need to unlock the page.
 *
 * Errors returned by this function are usually "soft", eg out of memory, or
 * queue full; callers should try a different route to write this page rather
 * than propagate an error back up the stack.
 *
 * Return: negative errno if an error occurs, 0 if submission was successful.
 */
int bdev_write_page(struct block_device *bdev, sector_t sector,
			struct page *page, struct writeback_control *wbc)
{
	int result;
	int rw = (wbc->sync_mode == WB_SYNC_ALL) ? WRITE_SYNC : WRITE;
	const struct block_device_operations *ops = bdev->bd_disk->fops;
	if (!ops->rw_page)
		return -EOPNOTSUPP;
	set_page_writeback(page);
	result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, rw);
	if (result)
		end_page_writeback(page);
	else
		unlock_page(page);
	return result;
}
EXPORT_SYMBOL_GPL(bdev_write_page);

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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;
}

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static void bdev_i_callback(struct rcu_head *head)
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{
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	struct inode *inode = container_of(head, struct inode, i_rcu);
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	struct bdev_inode *bdi = BDEV_I(inode);

	kmem_cache_free(bdev_cachep, bdi);
}

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static void bdev_destroy_inode(struct inode *inode)
{
	call_rcu(&inode->i_rcu, bdev_i_callback);
}

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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
	INIT_LIST_HEAD(&bdev->bd_holder_disks);
#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;
}

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static void bdev_evict_inode(struct inode *inode)
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{
	struct block_device *bdev = &BDEV_I(inode)->bdev;
	struct list_head *p;
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	truncate_inode_pages_final(&inode->i_data);
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	invalidate_inode_buffers(inode); /* is it needed here? */
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	clear_inode(inode);
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	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,
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	.evict_inode = bdev_evict_inode,
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};

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static struct dentry *bd_mount(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data)
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{
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	return mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC);
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}

static struct file_system_type bd_type = {
	.name		= "bdev",
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	.mount		= bd_mount,
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	.kill_sb	= kill_anon_super,
};

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static struct super_block *blockdev_superblock __read_mostly;
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void __init bdev_cache_init(void)
{
	int err;
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	static 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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	blockdev_superblock = bd_mnt->mnt_sb;   /* For writeback */
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}

/*
 * 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;
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		bdev->bd_super = NULL;
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		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);

592 593 594 595 596 597
/**
 * 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)
{
A
Al Viro 已提交
598
	ihold(bdev->bd_inode);
599 600
	return bdev;
}
601
EXPORT_SYMBOL(bdgrab);
602

L
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603 604
long nr_blockdev_pages(void)
{
605
	struct block_device *bdev;
L
Linus Torvalds 已提交
606 607
	long ret = 0;
	spin_lock(&bdev_lock);
608
	list_for_each_entry(bdev, &all_bdevs, bd_list) {
L
Linus Torvalds 已提交
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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;
625

L
Linus Torvalds 已提交
626 627
	spin_lock(&bdev_lock);
	bdev = inode->i_bdev;
628
	if (bdev) {
A
Al Viro 已提交
629
		ihold(bdev->bd_inode);
L
Linus Torvalds 已提交
630 631 632 633
		spin_unlock(&bdev_lock);
		return bdev;
	}
	spin_unlock(&bdev_lock);
634

L
Linus Torvalds 已提交
635 636 637
	bdev = bdget(inode->i_rdev);
	if (bdev) {
		spin_lock(&bdev_lock);
638 639
		if (!inode->i_bdev) {
			/*
A
Al Viro 已提交
640
			 * We take an additional reference to bd_inode,
641 642 643 644
			 * and it's released in clear_inode() of inode.
			 * So, we can access it via ->i_mapping always
			 * without igrab().
			 */
A
Al Viro 已提交
645
			ihold(bdev->bd_inode);
646 647 648 649
			inode->i_bdev = bdev;
			inode->i_mapping = bdev->bd_inode->i_mapping;
			list_add(&inode->i_devices, &bdev->bd_inodes);
		}
L
Linus Torvalds 已提交
650 651 652 653 654
		spin_unlock(&bdev_lock);
	}
	return bdev;
}

655
int sb_is_blkdev_sb(struct super_block *sb)
A
Al Viro 已提交
656 657 658 659
{
	return sb == blockdev_superblock;
}

L
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660 661 662 663
/* Call when you free inode */

void bd_forget(struct inode *inode)
{
664 665
	struct block_device *bdev = NULL;

L
Linus Torvalds 已提交
666
	spin_lock(&bdev_lock);
667 668 669
	if (!sb_is_blkdev_sb(inode->i_sb))
		bdev = inode->i_bdev;
	__bd_forget(inode);
L
Linus Torvalds 已提交
670
	spin_unlock(&bdev_lock);
671 672 673

	if (bdev)
		iput(bdev->bd_inode);
L
Linus Torvalds 已提交
674 675
}

T
Tejun Heo 已提交
676 677 678 679 680 681
/**
 * 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
 *
L
Lucas De Marchi 已提交
682
 * Test whether @bdev can be claimed by @holder.
T
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683 684 685 686 687 688 689 690 691
 *
 * 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)
L
Linus Torvalds 已提交
692 693
{
	if (bdev->bd_holder == holder)
T
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694
		return true;	 /* already a holder */
L
Linus Torvalds 已提交
695
	else if (bdev->bd_holder != NULL)
T
Tejun Heo 已提交
696
		return false; 	 /* held by someone else */
L
Linus Torvalds 已提交
697
	else if (bdev->bd_contains == bdev)
T
Tejun Heo 已提交
698
		return true;  	 /* is a whole device which isn't held */
L
Linus Torvalds 已提交
699

700
	else if (whole->bd_holder == bd_may_claim)
T
Tejun Heo 已提交
701 702 703
		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 */
L
Linus Torvalds 已提交
704
	else
T
Tejun Heo 已提交
705 706 707
		return true;	 /* is a partition of an un-held device */
}

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
/**
 * 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;

734 735
	/* if claiming is already in progress, wait for it to finish */
	if (whole->bd_claiming) {
736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758
		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
N
Nick Piggin 已提交
759 760 761 762 763 764 765
 * 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.
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
 *
 * 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);

791 792 793 794 795 796 797 798 799 800 801 802 803
	/*
	 * Normally, @bdev should equal what's returned from bdget_disk()
	 * if partno is 0; however, some drivers (floppy) use multiple
	 * bdev's for the same physical device and @bdev may be one of the
	 * aliases.  Keep @bdev if partno is 0.  This means claimer
	 * tracking is broken for those devices but it has always been that
	 * way.
	 */
	if (partno)
		whole = bdget_disk(disk, 0);
	else
		whole = bdgrab(bdev);

804
	module_put(disk->fops->owner);
805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823
	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);
	}
}

824
#ifdef CONFIG_SYSFS
825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841
struct bd_holder_disk {
	struct list_head	list;
	struct gendisk		*disk;
	int			refcnt;
};

static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
						  struct gendisk *disk)
{
	struct bd_holder_disk *holder;

	list_for_each_entry(holder, &bdev->bd_holder_disks, list)
		if (holder->disk == disk)
			return holder;
	return NULL;
}

842
static int add_symlink(struct kobject *from, struct kobject *to)
843
{
844
	return sysfs_create_link(from, to, kobject_name(to));
845 846 847 848 849 850 851
}

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

J
Jun'ichi Nomura 已提交
852
/**
853 854 855
 * bd_link_disk_holder - create symlinks between holding disk and slave bdev
 * @bdev: the claimed slave bdev
 * @disk: the holding disk
J
Jun'ichi Nomura 已提交
856
 *
857 858
 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
 *
859
 * This functions creates the following sysfs symlinks.
860
 *
861 862
 * - from "slaves" directory of the holder @disk to the claimed @bdev
 * - from "holders" directory of the @bdev to the holder @disk
863
 *
864 865
 * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
 * passed to bd_link_disk_holder(), then:
866
 *
867 868
 *   /sys/block/dm-0/slaves/sda --> /sys/block/sda
 *   /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
869
 *
870 871 872
 * The caller must have claimed @bdev before calling this function and
 * ensure that both @bdev and @disk are valid during the creation and
 * lifetime of these symlinks.
873
 *
874 875
 * CONTEXT:
 * Might sleep.
876
 *
877 878
 * RETURNS:
 * 0 on success, -errno on failure.
879
 */
880
int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
881
{
882
	struct bd_holder_disk *holder;
883
	int ret = 0;
884

885
	mutex_lock(&bdev->bd_mutex);
J
Jun'ichi Nomura 已提交
886

887
	WARN_ON_ONCE(!bdev->bd_holder);
888

889 890 891
	/* FIXME: remove the following once add_disk() handles errors */
	if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
		goto out_unlock;
892

893 894 895
	holder = bd_find_holder_disk(bdev, disk);
	if (holder) {
		holder->refcnt++;
896
		goto out_unlock;
897
	}
898

899 900 901
	holder = kzalloc(sizeof(*holder), GFP_KERNEL);
	if (!holder) {
		ret = -ENOMEM;
902 903
		goto out_unlock;
	}
904

905 906 907 908 909 910 911 912 913 914 915
	INIT_LIST_HEAD(&holder->list);
	holder->disk = disk;
	holder->refcnt = 1;

	ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
	if (ret)
		goto out_free;

	ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
	if (ret)
		goto out_del;
916 917 918 919 920
	/*
	 * bdev could be deleted beneath us which would implicitly destroy
	 * the holder directory.  Hold on to it.
	 */
	kobject_get(bdev->bd_part->holder_dir);
921 922 923 924 925 926 927 928

	list_add(&holder->list, &bdev->bd_holder_disks);
	goto out_unlock;

out_del:
	del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
out_free:
	kfree(holder);
929
out_unlock:
930
	mutex_unlock(&bdev->bd_mutex);
931
	return ret;
932
}
933
EXPORT_SYMBOL_GPL(bd_link_disk_holder);
934

935 936 937 938 939 940 941 942 943 944 945
/**
 * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
 * @bdev: the calimed slave bdev
 * @disk: the holding disk
 *
 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
 *
 * CONTEXT:
 * Might sleep.
 */
void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
946
{
947
	struct bd_holder_disk *holder;
948

949
	mutex_lock(&bdev->bd_mutex);
950

951 952 953 954 955 956
	holder = bd_find_holder_disk(bdev, disk);

	if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
		del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
		del_symlink(bdev->bd_part->holder_dir,
			    &disk_to_dev(disk)->kobj);
957
		kobject_put(bdev->bd_part->holder_dir);
958 959 960 961 962
		list_del_init(&holder->list);
		kfree(holder);
	}

	mutex_unlock(&bdev->bd_mutex);
L
Linus Torvalds 已提交
963
}
964
EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
965
#endif
L
Linus Torvalds 已提交
966

967 968 969 970
/**
 * flush_disk - invalidates all buffer-cache entries on a disk
 *
 * @bdev:      struct block device to be flushed
971
 * @kill_dirty: flag to guide handling of dirty inodes
972 973 974 975 976
 *
 * 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.
 */
977
static void flush_disk(struct block_device *bdev, bool kill_dirty)
978
{
979
	if (__invalidate_device(bdev, kill_dirty)) {
980 981 982 983 984 985 986 987 988 989
		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;
T
Tejun Heo 已提交
990
	if (disk_part_scan_enabled(bdev->bd_disk))
991 992 993
		bdev->bd_invalidated = 1;
}

994
/**
995
 * check_disk_size_change - checks for disk size change and adjusts bdev size.
996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015
 * @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);
1016
		flush_disk(bdev, false);
1017 1018 1019 1020
	}
}
EXPORT_SYMBOL(check_disk_size_change);

1021
/**
1022
 * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
1023 1024 1025 1026 1027 1028 1029 1030
 * @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)
{
1031
	struct block_device *bdev;
1032 1033 1034 1035 1036
	int ret = 0;

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

1037 1038 1039 1040 1041 1042
	bdev = bdget_disk(disk, 0);
	if (!bdev)
		return ret;

	mutex_lock(&bdev->bd_mutex);
	check_disk_size_change(disk, bdev);
1043
	bdev->bd_invalidated = 0;
1044 1045
	mutex_unlock(&bdev->bd_mutex);
	bdput(bdev);
1046 1047 1048 1049
	return ret;
}
EXPORT_SYMBOL(revalidate_disk);

L
Linus Torvalds 已提交
1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061
/*
 * 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;
1062
	const struct block_device_operations *bdops = disk->fops;
1063
	unsigned int events;
L
Linus Torvalds 已提交
1064

1065 1066 1067
	events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
				   DISK_EVENT_EJECT_REQUEST);
	if (!(events & DISK_EVENT_MEDIA_CHANGE))
L
Linus Torvalds 已提交
1068 1069
		return 0;

1070
	flush_disk(bdev, true);
L
Linus Torvalds 已提交
1071 1072 1073 1074 1075 1076 1077 1078 1079
	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)
{
1080
	unsigned bsize = bdev_logical_block_size(bdev);
L
Linus Torvalds 已提交
1081

1082 1083 1084
	mutex_lock(&bdev->bd_inode->i_mutex);
	i_size_write(bdev->bd_inode, size);
	mutex_unlock(&bdev->bd_inode->i_mutex);
L
Linus Torvalds 已提交
1085 1086 1087 1088 1089 1090 1091 1092 1093 1094
	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);

A
Al Viro 已提交
1095
static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
1096

1097 1098 1099 1100 1101 1102 1103
/*
 * bd_mutex locking:
 *
 *  mutex_lock(part->bd_mutex)
 *    mutex_lock_nested(whole->bd_mutex, 1)
 */

1104
static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
L
Linus Torvalds 已提交
1105 1106
{
	struct gendisk *disk;
1107
	struct module *owner;
1108
	int ret;
1109
	int partno;
1110 1111
	int perm = 0;

1112
	if (mode & FMODE_READ)
1113
		perm |= MAY_READ;
1114
	if (mode & FMODE_WRITE)
1115 1116 1117 1118
		perm |= MAY_WRITE;
	/*
	 * hooks: /n/, see "layering violations".
	 */
1119 1120 1121 1122 1123 1124
	if (!for_part) {
		ret = devcgroup_inode_permission(bdev->bd_inode, perm);
		if (ret != 0) {
			bdput(bdev);
			return ret;
		}
1125
	}
1126

1127
 restart:
T
Tejun Heo 已提交
1128

1129
	ret = -ENXIO;
1130
	disk = get_gendisk(bdev->bd_dev, &partno);
T
Tejun Heo 已提交
1131
	if (!disk)
1132
		goto out;
1133
	owner = disk->fops->owner;
L
Linus Torvalds 已提交
1134

1135
	disk_block_events(disk);
1136
	mutex_lock_nested(&bdev->bd_mutex, for_part);
L
Linus Torvalds 已提交
1137 1138
	if (!bdev->bd_openers) {
		bdev->bd_disk = disk;
1139
		bdev->bd_queue = disk->queue;
L
Linus Torvalds 已提交
1140
		bdev->bd_contains = bdev;
1141
		if (!partno) {
L
Linus Torvalds 已提交
1142
			struct backing_dev_info *bdi;
1143 1144 1145 1146 1147 1148

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

1149
			ret = 0;
L
Linus Torvalds 已提交
1150
			if (disk->fops->open) {
1151
				ret = disk->fops->open(bdev, mode);
1152 1153 1154 1155 1156 1157 1158 1159
				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;
					bdev->bd_disk = NULL;
1160
					bdev->bd_queue = NULL;
1161
					mutex_unlock(&bdev->bd_mutex);
1162 1163
					disk_unblock_events(disk);
					put_disk(disk);
1164
					module_put(owner);
1165 1166
					goto restart;
				}
L
Linus Torvalds 已提交
1167
			}
1168

1169
			if (!ret) {
1170 1171 1172 1173 1174
				bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
				bdi = blk_get_backing_dev_info(bdev);
				bdev_inode_switch_bdi(bdev->bd_inode, bdi);
			}

1175 1176 1177 1178 1179 1180
			/*
			 * If the device is invalidated, rescan partition
			 * if open succeeded or failed with -ENOMEDIUM.
			 * The latter is necessary to prevent ghost
			 * partitions on a removed medium.
			 */
1181 1182 1183 1184 1185 1186
			if (bdev->bd_invalidated) {
				if (!ret)
					rescan_partitions(disk, bdev);
				else if (ret == -ENOMEDIUM)
					invalidate_partitions(disk, bdev);
			}
1187 1188
			if (ret)
				goto out_clear;
L
Linus Torvalds 已提交
1189 1190 1191 1192 1193
		} else {
			struct block_device *whole;
			whole = bdget_disk(disk, 0);
			ret = -ENOMEM;
			if (!whole)
T
Tejun Heo 已提交
1194
				goto out_clear;
1195
			BUG_ON(for_part);
1196
			ret = __blkdev_get(whole, mode, 1);
L
Linus Torvalds 已提交
1197
			if (ret)
T
Tejun Heo 已提交
1198
				goto out_clear;
L
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1199
			bdev->bd_contains = whole;
1200 1201
			bdev_inode_switch_bdi(bdev->bd_inode,
				whole->bd_inode->i_data.backing_dev_info);
1202
			bdev->bd_part = disk_get_part(disk, partno);
1203
			if (!(disk->flags & GENHD_FL_UP) ||
1204
			    !bdev->bd_part || !bdev->bd_part->nr_sects) {
L
Linus Torvalds 已提交
1205
				ret = -ENXIO;
T
Tejun Heo 已提交
1206
				goto out_clear;
L
Linus Torvalds 已提交
1207
			}
1208
			bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
L
Linus Torvalds 已提交
1209 1210 1211
		}
	} else {
		if (bdev->bd_contains == bdev) {
1212 1213
			ret = 0;
			if (bdev->bd_disk->fops->open)
1214
				ret = bdev->bd_disk->fops->open(bdev, mode);
1215
			/* the same as first opener case, read comment there */
1216 1217 1218 1219 1220 1221
			if (bdev->bd_invalidated) {
				if (!ret)
					rescan_partitions(bdev->bd_disk, bdev);
				else if (ret == -ENOMEDIUM)
					invalidate_partitions(bdev->bd_disk, bdev);
			}
1222 1223
			if (ret)
				goto out_unlock_bdev;
L
Linus Torvalds 已提交
1224
		}
1225 1226
		/* only one opener holds refs to the module and disk */
		put_disk(disk);
1227
		module_put(owner);
L
Linus Torvalds 已提交
1228 1229
	}
	bdev->bd_openers++;
1230 1231
	if (for_part)
		bdev->bd_part_count++;
1232
	mutex_unlock(&bdev->bd_mutex);
1233
	disk_unblock_events(disk);
L
Linus Torvalds 已提交
1234 1235
	return 0;

T
Tejun Heo 已提交
1236
 out_clear:
1237
	disk_put_part(bdev->bd_part);
L
Linus Torvalds 已提交
1238
	bdev->bd_disk = NULL;
T
Tejun Heo 已提交
1239
	bdev->bd_part = NULL;
1240
	bdev->bd_queue = NULL;
1241
	bdev_inode_switch_bdi(bdev->bd_inode, &default_backing_dev_info);
L
Linus Torvalds 已提交
1242
	if (bdev != bdev->bd_contains)
1243
		__blkdev_put(bdev->bd_contains, mode, 1);
L
Linus Torvalds 已提交
1244
	bdev->bd_contains = NULL;
T
Tejun Heo 已提交
1245
 out_unlock_bdev:
1246
	mutex_unlock(&bdev->bd_mutex);
1247
	disk_unblock_events(disk);
T
Tejun Heo 已提交
1248
	put_disk(disk);
1249
	module_put(owner);
1250
 out:
T
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1251 1252
	bdput(bdev);

L
Linus Torvalds 已提交
1253 1254 1255
	return ret;
}

1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274
/**
 * blkdev_get - open a block device
 * @bdev: block_device to open
 * @mode: FMODE_* mask
 * @holder: exclusive holder identifier
 *
 * Open @bdev with @mode.  If @mode includes %FMODE_EXCL, @bdev is
 * open with exclusive access.  Specifying %FMODE_EXCL with %NULL
 * @holder is invalid.  Exclusive opens may nest for the same @holder.
 *
 * On success, the reference count of @bdev is unchanged.  On failure,
 * @bdev is put.
 *
 * CONTEXT:
 * Might sleep.
 *
 * RETURNS:
 * 0 on success, -errno on failure.
 */
1275
int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
L
Linus Torvalds 已提交
1276
{
1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292
	struct block_device *whole = NULL;
	int res;

	WARN_ON_ONCE((mode & FMODE_EXCL) && !holder);

	if ((mode & FMODE_EXCL) && holder) {
		whole = bd_start_claiming(bdev, holder);
		if (IS_ERR(whole)) {
			bdput(bdev);
			return PTR_ERR(whole);
		}
	}

	res = __blkdev_get(bdev, mode, 0);

	if (whole) {
1293 1294
		struct gendisk *disk = whole->bd_disk;

1295
		/* finish claiming */
1296
		mutex_lock(&bdev->bd_mutex);
1297 1298
		spin_lock(&bdev_lock);

1299
		if (!res) {
1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318
			BUG_ON(!bd_may_claim(bdev, whole, holder));
			/*
			 * Note that for a whole device bd_holders
			 * will be incremented twice, and bd_holder
			 * will be set to bd_may_claim before being
			 * set to holder
			 */
			whole->bd_holders++;
			whole->bd_holder = bd_may_claim;
			bdev->bd_holders++;
			bdev->bd_holder = holder;
		}

		/* tell others that we're done */
		BUG_ON(whole->bd_claiming != holder);
		whole->bd_claiming = NULL;
		wake_up_bit(&whole->bd_claiming, 0);

		spin_unlock(&bdev_lock);
1319 1320

		/*
1321 1322 1323 1324 1325
		 * Block event polling for write claims if requested.  Any
		 * write holder makes the write_holder state stick until
		 * all are released.  This is good enough and tracking
		 * individual writeable reference is too fragile given the
		 * way @mode is used in blkdev_get/put().
1326
		 */
1327 1328
		if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder &&
		    (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
1329
			bdev->bd_write_holder = true;
1330
			disk_block_events(disk);
1331 1332 1333
		}

		mutex_unlock(&bdev->bd_mutex);
1334
		bdput(whole);
1335 1336 1337
	}

	return res;
1338
}
L
Linus Torvalds 已提交
1339 1340
EXPORT_SYMBOL(blkdev_get);

1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371
/**
 * blkdev_get_by_path - open a block device by name
 * @path: path to the block device to open
 * @mode: FMODE_* mask
 * @holder: exclusive holder identifier
 *
 * Open the blockdevice described by the device file at @path.  @mode
 * and @holder are identical to blkdev_get().
 *
 * On success, the returned block_device has reference count of one.
 *
 * CONTEXT:
 * Might sleep.
 *
 * RETURNS:
 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
 */
struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
					void *holder)
{
	struct block_device *bdev;
	int err;

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

	err = blkdev_get(bdev, mode, holder);
	if (err)
		return ERR_PTR(err);

1372 1373 1374 1375 1376
	if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) {
		blkdev_put(bdev, mode);
		return ERR_PTR(-EACCES);
	}

1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419
	return bdev;
}
EXPORT_SYMBOL(blkdev_get_by_path);

/**
 * blkdev_get_by_dev - open a block device by device number
 * @dev: device number of block device to open
 * @mode: FMODE_* mask
 * @holder: exclusive holder identifier
 *
 * Open the blockdevice described by device number @dev.  @mode and
 * @holder are identical to blkdev_get().
 *
 * 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.
 *
 * On success, the returned block_device has reference count of one.
 *
 * CONTEXT:
 * Might sleep.
 *
 * RETURNS:
 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
 */
struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
{
	struct block_device *bdev;
	int err;

	bdev = bdget(dev);
	if (!bdev)
		return ERR_PTR(-ENOMEM);

	err = blkdev_get(bdev, mode, holder);
	if (err)
		return ERR_PTR(err);

	return bdev;
}
EXPORT_SYMBOL(blkdev_get_by_dev);

L
Linus Torvalds 已提交
1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431
static int blkdev_open(struct inode * inode, struct file * filp)
{
	struct block_device *bdev;

	/*
	 * 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;

1432 1433 1434 1435 1436 1437 1438
	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;

L
Linus Torvalds 已提交
1439
	bdev = bd_acquire(inode);
1440 1441
	if (bdev == NULL)
		return -ENOMEM;
L
Linus Torvalds 已提交
1442

1443 1444
	filp->f_mapping = bdev->bd_inode->i_mapping;

1445
	return blkdev_get(bdev, filp->f_mode, filp);
L
Linus Torvalds 已提交
1446 1447
}

A
Al Viro 已提交
1448
static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
1449 1450
{
	struct gendisk *disk = bdev->bd_disk;
1451
	struct block_device *victim = NULL;
1452

1453
	mutex_lock_nested(&bdev->bd_mutex, for_part);
1454 1455 1456
	if (for_part)
		bdev->bd_part_count--;

1457
	if (!--bdev->bd_openers) {
1458
		WARN_ON_ONCE(bdev->bd_holders);
1459 1460
		sync_blockdev(bdev);
		kill_bdev(bdev);
1461 1462 1463 1464 1465
		/* ->release can cause the old bdi to disappear,
		 * so must switch it out first
		 */
		bdev_inode_switch_bdi(bdev->bd_inode,
					&default_backing_dev_info);
1466 1467 1468
	}
	if (bdev->bd_contains == bdev) {
		if (disk->fops->release)
1469
			disk->fops->release(disk, mode);
1470 1471 1472 1473
	}
	if (!bdev->bd_openers) {
		struct module *owner = disk->fops->owner;

T
Tejun Heo 已提交
1474 1475
		disk_put_part(bdev->bd_part);
		bdev->bd_part = NULL;
1476
		bdev->bd_disk = NULL;
1477 1478
		if (bdev != bdev->bd_contains)
			victim = bdev->bd_contains;
1479
		bdev->bd_contains = NULL;
1480 1481 1482

		put_disk(disk);
		module_put(owner);
1483 1484 1485
	}
	mutex_unlock(&bdev->bd_mutex);
	bdput(bdev);
1486
	if (victim)
A
Al Viro 已提交
1487
		__blkdev_put(victim, mode, 1);
1488 1489
}

A
Al Viro 已提交
1490
void blkdev_put(struct block_device *bdev, fmode_t mode)
1491
{
1492 1493
	mutex_lock(&bdev->bd_mutex);

1494
	if (mode & FMODE_EXCL) {
1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514
		bool bdev_free;

		/*
		 * Release a claim on the device.  The holder fields
		 * are protected with bdev_lock.  bd_mutex is to
		 * synchronize disk_holder unlinking.
		 */
		spin_lock(&bdev_lock);

		WARN_ON_ONCE(--bdev->bd_holders < 0);
		WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0);

		/* bd_contains might point to self, check in a separate step */
		if ((bdev_free = !bdev->bd_holders))
			bdev->bd_holder = NULL;
		if (!bdev->bd_contains->bd_holders)
			bdev->bd_contains->bd_holder = NULL;

		spin_unlock(&bdev_lock);

1515 1516 1517 1518
		/*
		 * If this was the last claim, remove holder link and
		 * unblock evpoll if it was a write holder.
		 */
1519 1520 1521
		if (bdev_free && bdev->bd_write_holder) {
			disk_unblock_events(bdev->bd_disk);
			bdev->bd_write_holder = false;
1522
		}
1523
	}
1524

1525 1526 1527 1528 1529 1530 1531 1532 1533
	/*
	 * Trigger event checking and tell drivers to flush MEDIA_CHANGE
	 * event.  This is to ensure detection of media removal commanded
	 * from userland - e.g. eject(1).
	 */
	disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE);

	mutex_unlock(&bdev->bd_mutex);

A
Al Viro 已提交
1534
	__blkdev_put(bdev, mode, 0);
1535
}
1536 1537
EXPORT_SYMBOL(blkdev_put);

L
Linus Torvalds 已提交
1538 1539 1540
static int blkdev_close(struct inode * inode, struct file * filp)
{
	struct block_device *bdev = I_BDEV(filp->f_mapping->host);
A
Al Viro 已提交
1541 1542
	blkdev_put(bdev, filp->f_mode);
	return 0;
L
Linus Torvalds 已提交
1543 1544
}

1545
static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
L
Linus Torvalds 已提交
1546
{
1547 1548
	struct block_device *bdev = I_BDEV(file->f_mapping->host);
	fmode_t mode = file->f_mode;
1549 1550 1551 1552 1553

	/*
	 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
	 * to updated it before every ioctl.
	 */
1554
	if (file->f_flags & O_NDELAY)
1555 1556 1557 1558
		mode |= FMODE_NDELAY;
	else
		mode &= ~FMODE_NDELAY;

1559
	return blkdev_ioctl(bdev, mode, cmd, arg);
L
Linus Torvalds 已提交
1560 1561
}

1562 1563 1564 1565 1566 1567 1568
/*
 * 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.
 */
1569
ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
1570 1571
{
	struct file *file = iocb->ki_filp;
1572
	struct blk_plug plug;
1573 1574
	ssize_t ret;

1575
	blk_start_plug(&plug);
1576
	ret = __generic_file_write_iter(iocb, from);
1577
	if (ret > 0) {
1578
		ssize_t err;
1579
		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
1580
		if (err < 0)
1581 1582
			ret = err;
	}
1583
	blk_finish_plug(&plug);
1584 1585
	return ret;
}
1586
EXPORT_SYMBOL_GPL(blkdev_write_iter);
1587

1588
ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
1589 1590 1591 1592
{
	struct file *file = iocb->ki_filp;
	struct inode *bd_inode = file->f_mapping->host;
	loff_t size = i_size_read(bd_inode);
1593
	loff_t pos = iocb->ki_pos;
1594 1595 1596 1597 1598

	if (pos >= size)
		return 0;

	size -= pos;
1599 1600
	iov_iter_truncate(to, size);
	return generic_file_read_iter(iocb, to);
1601
}
1602
EXPORT_SYMBOL_GPL(blkdev_read_iter);
1603

1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617
/*
 * 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
1618
static const struct address_space_operations def_blk_aops = {
L
Linus Torvalds 已提交
1619
	.readpage	= blkdev_readpage,
1620
	.readpages	= blkdev_readpages,
L
Linus Torvalds 已提交
1621
	.writepage	= blkdev_writepage,
N
Nick Piggin 已提交
1622 1623
	.write_begin	= blkdev_write_begin,
	.write_end	= blkdev_write_end,
L
Linus Torvalds 已提交
1624
	.writepages	= generic_writepages,
1625
	.releasepage	= blkdev_releasepage,
L
Linus Torvalds 已提交
1626
	.direct_IO	= blkdev_direct_IO,
1627
	.is_dirty_writeback = buffer_check_dirty_writeback,
L
Linus Torvalds 已提交
1628 1629
};

1630
const struct file_operations def_blk_fops = {
L
Linus Torvalds 已提交
1631 1632 1633
	.open		= blkdev_open,
	.release	= blkdev_close,
	.llseek		= block_llseek,
1634
	.read		= new_sync_read,
1635
	.write		= new_sync_write,
1636
	.read_iter	= blkdev_read_iter,
1637
	.write_iter	= blkdev_write_iter,
1638
	.mmap		= generic_file_mmap,
1639
	.fsync		= blkdev_fsync,
1640
	.unlocked_ioctl	= block_ioctl,
L
Linus Torvalds 已提交
1641 1642 1643
#ifdef CONFIG_COMPAT
	.compat_ioctl	= compat_blkdev_ioctl,
#endif
1644
	.splice_read	= generic_file_splice_read,
A
Al Viro 已提交
1645
	.splice_write	= iter_file_splice_write,
L
Linus Torvalds 已提交
1646 1647 1648 1649 1650 1651 1652
};

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);
1653
	res = blkdev_ioctl(bdev, 0, cmd, arg);
L
Linus Torvalds 已提交
1654 1655 1656 1657 1658 1659 1660 1661
	set_fs(old_fs);
	return res;
}

EXPORT_SYMBOL(ioctl_by_bdev);

/**
 * lookup_bdev  - lookup a struct block_device by name
1662
 * @pathname:	special file representing the block device
L
Linus Torvalds 已提交
1663
 *
1664
 * Get a reference to the blockdevice at @pathname in the current
L
Linus Torvalds 已提交
1665 1666 1667
 * namespace if possible and return it.  Return ERR_PTR(error)
 * otherwise.
 */
1668
struct block_device *lookup_bdev(const char *pathname)
L
Linus Torvalds 已提交
1669 1670 1671
{
	struct block_device *bdev;
	struct inode *inode;
1672
	struct path path;
L
Linus Torvalds 已提交
1673 1674
	int error;

1675
	if (!pathname || !*pathname)
L
Linus Torvalds 已提交
1676 1677
		return ERR_PTR(-EINVAL);

1678
	error = kern_path(pathname, LOOKUP_FOLLOW, &path);
L
Linus Torvalds 已提交
1679 1680 1681
	if (error)
		return ERR_PTR(error);

1682
	inode = path.dentry->d_inode;
L
Linus Torvalds 已提交
1683 1684 1685 1686
	error = -ENOTBLK;
	if (!S_ISBLK(inode->i_mode))
		goto fail;
	error = -EACCES;
1687
	if (path.mnt->mnt_flags & MNT_NODEV)
L
Linus Torvalds 已提交
1688 1689 1690 1691 1692 1693
		goto fail;
	error = -ENOMEM;
	bdev = bd_acquire(inode);
	if (!bdev)
		goto fail;
out:
1694
	path_put(&path);
L
Linus Torvalds 已提交
1695 1696 1697 1698 1699
	return bdev;
fail:
	bdev = ERR_PTR(error);
	goto out;
}
1700
EXPORT_SYMBOL(lookup_bdev);
L
Linus Torvalds 已提交
1701

1702
int __invalidate_device(struct block_device *bdev, bool kill_dirty)
1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714
{
	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);
1715
		res = invalidate_inodes(sb, kill_dirty);
1716 1717
		drop_super(sb);
	}
1718
	invalidate_bdev(bdev);
1719 1720 1721
	return res;
}
EXPORT_SYMBOL(__invalidate_device);
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void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
{
	struct inode *inode, *old_inode = NULL;

	spin_lock(&inode_sb_list_lock);
	list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
		struct address_space *mapping = inode->i_mapping;

		spin_lock(&inode->i_lock);
		if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
		    mapping->nrpages == 0) {
			spin_unlock(&inode->i_lock);
			continue;
		}
		__iget(inode);
		spin_unlock(&inode->i_lock);
		spin_unlock(&inode_sb_list_lock);
		/*
		 * We hold a reference to 'inode' so it couldn't have been
		 * removed from s_inodes list while we dropped the
		 * inode_sb_list_lock.  We cannot iput the inode now as we can
		 * be holding the last reference and we cannot iput it under
		 * inode_sb_list_lock. So we keep the reference and iput it
		 * later.
		 */
		iput(old_inode);
		old_inode = inode;

		func(I_BDEV(inode), arg);

		spin_lock(&inode_sb_list_lock);
	}
	spin_unlock(&inode_sb_list_lock);
	iput(old_inode);
}