block_dev.c 44.2 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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	if (sb->s_op->freeze_super)
		error = sb->s_op->freeze_super(sb);
	else
		error = freeze_super(sb);
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	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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	if (sb->s_op->thaw_super)
		error = sb->s_op->thaw_super(sb);
	else
		error = thaw_super(sb);
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	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;
577
		bdev->bd_super = NULL;
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578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597
		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);

598 599 600 601 602 603
/**
 * 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
604
	ihold(bdev->bd_inode);
605 606
	return bdev;
}
607
EXPORT_SYMBOL(bdgrab);
608

L
Linus Torvalds 已提交
609 610
long nr_blockdev_pages(void)
{
611
	struct block_device *bdev;
L
Linus Torvalds 已提交
612 613
	long ret = 0;
	spin_lock(&bdev_lock);
614
	list_for_each_entry(bdev, &all_bdevs, bd_list) {
L
Linus Torvalds 已提交
615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630
		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;
631

L
Linus Torvalds 已提交
632 633
	spin_lock(&bdev_lock);
	bdev = inode->i_bdev;
634
	if (bdev) {
A
Al Viro 已提交
635
		ihold(bdev->bd_inode);
L
Linus Torvalds 已提交
636 637 638 639
		spin_unlock(&bdev_lock);
		return bdev;
	}
	spin_unlock(&bdev_lock);
640

L
Linus Torvalds 已提交
641 642 643
	bdev = bdget(inode->i_rdev);
	if (bdev) {
		spin_lock(&bdev_lock);
644 645
		if (!inode->i_bdev) {
			/*
A
Al Viro 已提交
646
			 * We take an additional reference to bd_inode,
647 648 649 650
			 * 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
651
			ihold(bdev->bd_inode);
652 653 654 655
			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
656 657 658 659 660
		spin_unlock(&bdev_lock);
	}
	return bdev;
}

661
int sb_is_blkdev_sb(struct super_block *sb)
A
Al Viro 已提交
662 663 664 665
{
	return sb == blockdev_superblock;
}

L
Linus Torvalds 已提交
666 667 668 669
/* Call when you free inode */

void bd_forget(struct inode *inode)
{
670 671
	struct block_device *bdev = NULL;

L
Linus Torvalds 已提交
672
	spin_lock(&bdev_lock);
673 674 675
	if (!sb_is_blkdev_sb(inode->i_sb))
		bdev = inode->i_bdev;
	__bd_forget(inode);
L
Linus Torvalds 已提交
676
	spin_unlock(&bdev_lock);
677 678 679

	if (bdev)
		iput(bdev->bd_inode);
L
Linus Torvalds 已提交
680 681
}

T
Tejun Heo 已提交
682 683 684 685 686 687
/**
 * 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
688
 * Test whether @bdev can be claimed by @holder.
T
Tejun Heo 已提交
689 690 691 692 693 694 695 696 697
 *
 * 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
698 699
{
	if (bdev->bd_holder == holder)
T
Tejun Heo 已提交
700
		return true;	 /* already a holder */
L
Linus Torvalds 已提交
701
	else if (bdev->bd_holder != NULL)
T
Tejun Heo 已提交
702
		return false; 	 /* held by someone else */
L
Linus Torvalds 已提交
703
	else if (bdev->bd_contains == bdev)
T
Tejun Heo 已提交
704
		return true;  	 /* is a whole device which isn't held */
L
Linus Torvalds 已提交
705

706
	else if (whole->bd_holder == bd_may_claim)
T
Tejun Heo 已提交
707 708 709
		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
710
	else
T
Tejun Heo 已提交
711 712 713
		return true;	 /* is a partition of an un-held device */
}

714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739
/**
 * 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;

740 741
	/* if claiming is already in progress, wait for it to finish */
	if (whole->bd_claiming) {
742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764
		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
765 766 767 768 769 770 771
 * 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.
772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796
 *
 * 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);

797 798 799 800 801 802 803 804 805 806 807 808 809
	/*
	 * 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);

810
	module_put(disk->fops->owner);
811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829
	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);
	}
}

830
#ifdef CONFIG_SYSFS
831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847
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;
}

848
static int add_symlink(struct kobject *from, struct kobject *to)
849
{
850
	return sysfs_create_link(from, to, kobject_name(to));
851 852 853 854 855 856 857
}

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

J
Jun'ichi Nomura 已提交
858
/**
859 860 861
 * 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
862
 *
863 864
 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
 *
865
 * This functions creates the following sysfs symlinks.
866
 *
867 868
 * - from "slaves" directory of the holder @disk to the claimed @bdev
 * - from "holders" directory of the @bdev to the holder @disk
869
 *
870 871
 * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
 * passed to bd_link_disk_holder(), then:
872
 *
873 874
 *   /sys/block/dm-0/slaves/sda --> /sys/block/sda
 *   /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
875
 *
876 877 878
 * 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.
879
 *
880 881
 * CONTEXT:
 * Might sleep.
882
 *
883 884
 * RETURNS:
 * 0 on success, -errno on failure.
885
 */
886
int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
887
{
888
	struct bd_holder_disk *holder;
889
	int ret = 0;
890

891
	mutex_lock(&bdev->bd_mutex);
J
Jun'ichi Nomura 已提交
892

893
	WARN_ON_ONCE(!bdev->bd_holder);
894

895 896 897
	/* FIXME: remove the following once add_disk() handles errors */
	if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
		goto out_unlock;
898

899 900 901
	holder = bd_find_holder_disk(bdev, disk);
	if (holder) {
		holder->refcnt++;
902
		goto out_unlock;
903
	}
904

905 906 907
	holder = kzalloc(sizeof(*holder), GFP_KERNEL);
	if (!holder) {
		ret = -ENOMEM;
908 909
		goto out_unlock;
	}
910

911 912 913 914 915 916 917 918 919 920 921
	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;
922 923 924 925 926
	/*
	 * bdev could be deleted beneath us which would implicitly destroy
	 * the holder directory.  Hold on to it.
	 */
	kobject_get(bdev->bd_part->holder_dir);
927 928 929 930 931 932 933 934

	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);
935
out_unlock:
936
	mutex_unlock(&bdev->bd_mutex);
937
	return ret;
938
}
939
EXPORT_SYMBOL_GPL(bd_link_disk_holder);
940

941 942 943 944 945 946 947 948 949 950 951
/**
 * 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)
952
{
953
	struct bd_holder_disk *holder;
954

955
	mutex_lock(&bdev->bd_mutex);
956

957 958 959 960 961 962
	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);
963
		kobject_put(bdev->bd_part->holder_dir);
964 965 966 967 968
		list_del_init(&holder->list);
		kfree(holder);
	}

	mutex_unlock(&bdev->bd_mutex);
L
Linus Torvalds 已提交
969
}
970
EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
971
#endif
L
Linus Torvalds 已提交
972

973 974 975 976
/**
 * flush_disk - invalidates all buffer-cache entries on a disk
 *
 * @bdev:      struct block device to be flushed
977
 * @kill_dirty: flag to guide handling of dirty inodes
978 979 980 981 982
 *
 * 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.
 */
983
static void flush_disk(struct block_device *bdev, bool kill_dirty)
984
{
985
	if (__invalidate_device(bdev, kill_dirty)) {
986 987 988 989 990 991 992 993 994 995
		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
996
	if (disk_part_scan_enabled(bdev->bd_disk))
997 998 999
		bdev->bd_invalidated = 1;
}

1000
/**
1001
 * check_disk_size_change - checks for disk size change and adjusts bdev size.
1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021
 * @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);
1022
		flush_disk(bdev, false);
1023 1024 1025 1026
	}
}
EXPORT_SYMBOL(check_disk_size_change);

1027
/**
1028
 * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
1029 1030 1031 1032 1033 1034 1035 1036
 * @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)
{
1037
	struct block_device *bdev;
1038 1039 1040 1041 1042
	int ret = 0;

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

1043 1044 1045 1046 1047 1048
	bdev = bdget_disk(disk, 0);
	if (!bdev)
		return ret;

	mutex_lock(&bdev->bd_mutex);
	check_disk_size_change(disk, bdev);
1049
	bdev->bd_invalidated = 0;
1050 1051
	mutex_unlock(&bdev->bd_mutex);
	bdput(bdev);
1052 1053 1054 1055
	return ret;
}
EXPORT_SYMBOL(revalidate_disk);

L
Linus Torvalds 已提交
1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067
/*
 * 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;
1068
	const struct block_device_operations *bdops = disk->fops;
1069
	unsigned int events;
L
Linus Torvalds 已提交
1070

1071 1072 1073
	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
1074 1075
		return 0;

1076
	flush_disk(bdev, true);
L
Linus Torvalds 已提交
1077 1078 1079 1080 1081 1082 1083 1084 1085
	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)
{
1086
	unsigned bsize = bdev_logical_block_size(bdev);
L
Linus Torvalds 已提交
1087

1088 1089 1090
	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
1091 1092 1093 1094 1095 1096 1097 1098 1099 1100
	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
1101
static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
1102

1103 1104 1105 1106 1107 1108 1109
/*
 * bd_mutex locking:
 *
 *  mutex_lock(part->bd_mutex)
 *    mutex_lock_nested(whole->bd_mutex, 1)
 */

1110
static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
L
Linus Torvalds 已提交
1111 1112
{
	struct gendisk *disk;
1113
	struct module *owner;
1114
	int ret;
1115
	int partno;
1116 1117
	int perm = 0;

1118
	if (mode & FMODE_READ)
1119
		perm |= MAY_READ;
1120
	if (mode & FMODE_WRITE)
1121 1122 1123 1124
		perm |= MAY_WRITE;
	/*
	 * hooks: /n/, see "layering violations".
	 */
1125 1126 1127 1128 1129 1130
	if (!for_part) {
		ret = devcgroup_inode_permission(bdev->bd_inode, perm);
		if (ret != 0) {
			bdput(bdev);
			return ret;
		}
1131
	}
1132

1133
 restart:
T
Tejun Heo 已提交
1134

1135
	ret = -ENXIO;
1136
	disk = get_gendisk(bdev->bd_dev, &partno);
T
Tejun Heo 已提交
1137
	if (!disk)
1138
		goto out;
1139
	owner = disk->fops->owner;
L
Linus Torvalds 已提交
1140

1141
	disk_block_events(disk);
1142
	mutex_lock_nested(&bdev->bd_mutex, for_part);
L
Linus Torvalds 已提交
1143 1144
	if (!bdev->bd_openers) {
		bdev->bd_disk = disk;
1145
		bdev->bd_queue = disk->queue;
L
Linus Torvalds 已提交
1146
		bdev->bd_contains = bdev;
1147
		if (!partno) {
L
Linus Torvalds 已提交
1148
			struct backing_dev_info *bdi;
1149 1150 1151 1152 1153 1154

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

1155
			ret = 0;
L
Linus Torvalds 已提交
1156
			if (disk->fops->open) {
1157
				ret = disk->fops->open(bdev, mode);
1158 1159 1160 1161 1162 1163 1164 1165
				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;
1166
					bdev->bd_queue = NULL;
1167
					mutex_unlock(&bdev->bd_mutex);
1168 1169
					disk_unblock_events(disk);
					put_disk(disk);
1170
					module_put(owner);
1171 1172
					goto restart;
				}
L
Linus Torvalds 已提交
1173
			}
1174

1175
			if (!ret) {
1176 1177 1178 1179 1180
				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);
			}

1181 1182 1183 1184 1185 1186
			/*
			 * 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.
			 */
1187 1188 1189 1190 1191 1192
			if (bdev->bd_invalidated) {
				if (!ret)
					rescan_partitions(disk, bdev);
				else if (ret == -ENOMEDIUM)
					invalidate_partitions(disk, bdev);
			}
1193 1194
			if (ret)
				goto out_clear;
L
Linus Torvalds 已提交
1195 1196 1197 1198 1199
		} else {
			struct block_device *whole;
			whole = bdget_disk(disk, 0);
			ret = -ENOMEM;
			if (!whole)
T
Tejun Heo 已提交
1200
				goto out_clear;
1201
			BUG_ON(for_part);
1202
			ret = __blkdev_get(whole, mode, 1);
L
Linus Torvalds 已提交
1203
			if (ret)
T
Tejun Heo 已提交
1204
				goto out_clear;
L
Linus Torvalds 已提交
1205
			bdev->bd_contains = whole;
1206 1207
			bdev_inode_switch_bdi(bdev->bd_inode,
				whole->bd_inode->i_data.backing_dev_info);
1208
			bdev->bd_part = disk_get_part(disk, partno);
1209
			if (!(disk->flags & GENHD_FL_UP) ||
1210
			    !bdev->bd_part || !bdev->bd_part->nr_sects) {
L
Linus Torvalds 已提交
1211
				ret = -ENXIO;
T
Tejun Heo 已提交
1212
				goto out_clear;
L
Linus Torvalds 已提交
1213
			}
1214
			bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
L
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1215 1216 1217
		}
	} else {
		if (bdev->bd_contains == bdev) {
1218 1219
			ret = 0;
			if (bdev->bd_disk->fops->open)
1220
				ret = bdev->bd_disk->fops->open(bdev, mode);
1221
			/* the same as first opener case, read comment there */
1222 1223 1224 1225 1226 1227
			if (bdev->bd_invalidated) {
				if (!ret)
					rescan_partitions(bdev->bd_disk, bdev);
				else if (ret == -ENOMEDIUM)
					invalidate_partitions(bdev->bd_disk, bdev);
			}
1228 1229
			if (ret)
				goto out_unlock_bdev;
L
Linus Torvalds 已提交
1230
		}
1231 1232
		/* only one opener holds refs to the module and disk */
		put_disk(disk);
1233
		module_put(owner);
L
Linus Torvalds 已提交
1234 1235
	}
	bdev->bd_openers++;
1236 1237
	if (for_part)
		bdev->bd_part_count++;
1238
	mutex_unlock(&bdev->bd_mutex);
1239
	disk_unblock_events(disk);
L
Linus Torvalds 已提交
1240 1241
	return 0;

T
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1242
 out_clear:
1243
	disk_put_part(bdev->bd_part);
L
Linus Torvalds 已提交
1244
	bdev->bd_disk = NULL;
T
Tejun Heo 已提交
1245
	bdev->bd_part = NULL;
1246
	bdev->bd_queue = NULL;
1247
	bdev_inode_switch_bdi(bdev->bd_inode, &default_backing_dev_info);
L
Linus Torvalds 已提交
1248
	if (bdev != bdev->bd_contains)
1249
		__blkdev_put(bdev->bd_contains, mode, 1);
L
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1250
	bdev->bd_contains = NULL;
T
Tejun Heo 已提交
1251
 out_unlock_bdev:
1252
	mutex_unlock(&bdev->bd_mutex);
1253
	disk_unblock_events(disk);
T
Tejun Heo 已提交
1254
	put_disk(disk);
1255
	module_put(owner);
1256
 out:
T
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1257 1258
	bdput(bdev);

L
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1259 1260 1261
	return ret;
}

1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280
/**
 * 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.
 */
1281
int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
L
Linus Torvalds 已提交
1282
{
1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298
	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) {
1299 1300
		struct gendisk *disk = whole->bd_disk;

1301
		/* finish claiming */
1302
		mutex_lock(&bdev->bd_mutex);
1303 1304
		spin_lock(&bdev_lock);

1305
		if (!res) {
1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324
			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);
1325 1326

		/*
1327 1328 1329 1330 1331
		 * 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().
1332
		 */
1333 1334
		if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder &&
		    (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
1335
			bdev->bd_write_holder = true;
1336
			disk_block_events(disk);
1337 1338 1339
		}

		mutex_unlock(&bdev->bd_mutex);
1340
		bdput(whole);
1341 1342 1343
	}

	return res;
1344
}
L
Linus Torvalds 已提交
1345 1346
EXPORT_SYMBOL(blkdev_get);

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 1372 1373 1374 1375 1376 1377
/**
 * 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);

1378 1379 1380 1381 1382
	if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) {
		blkdev_put(bdev, mode);
		return ERR_PTR(-EACCES);
	}

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 1420 1421 1422 1423 1424 1425
	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
1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437
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;

1438 1439 1440 1441 1442 1443 1444
	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
1445
	bdev = bd_acquire(inode);
1446 1447
	if (bdev == NULL)
		return -ENOMEM;
L
Linus Torvalds 已提交
1448

1449 1450
	filp->f_mapping = bdev->bd_inode->i_mapping;

1451
	return blkdev_get(bdev, filp->f_mode, filp);
L
Linus Torvalds 已提交
1452 1453
}

A
Al Viro 已提交
1454
static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
1455 1456
{
	struct gendisk *disk = bdev->bd_disk;
1457
	struct block_device *victim = NULL;
1458

1459
	mutex_lock_nested(&bdev->bd_mutex, for_part);
1460 1461 1462
	if (for_part)
		bdev->bd_part_count--;

1463
	if (!--bdev->bd_openers) {
1464
		WARN_ON_ONCE(bdev->bd_holders);
1465 1466
		sync_blockdev(bdev);
		kill_bdev(bdev);
1467 1468 1469 1470 1471
		/* ->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);
1472 1473 1474
	}
	if (bdev->bd_contains == bdev) {
		if (disk->fops->release)
1475
			disk->fops->release(disk, mode);
1476 1477 1478 1479
	}
	if (!bdev->bd_openers) {
		struct module *owner = disk->fops->owner;

T
Tejun Heo 已提交
1480 1481
		disk_put_part(bdev->bd_part);
		bdev->bd_part = NULL;
1482
		bdev->bd_disk = NULL;
1483 1484
		if (bdev != bdev->bd_contains)
			victim = bdev->bd_contains;
1485
		bdev->bd_contains = NULL;
1486 1487 1488

		put_disk(disk);
		module_put(owner);
1489 1490 1491
	}
	mutex_unlock(&bdev->bd_mutex);
	bdput(bdev);
1492
	if (victim)
A
Al Viro 已提交
1493
		__blkdev_put(victim, mode, 1);
1494 1495
}

A
Al Viro 已提交
1496
void blkdev_put(struct block_device *bdev, fmode_t mode)
1497
{
1498 1499
	mutex_lock(&bdev->bd_mutex);

1500
	if (mode & FMODE_EXCL) {
1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520
		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);

1521 1522 1523 1524
		/*
		 * If this was the last claim, remove holder link and
		 * unblock evpoll if it was a write holder.
		 */
1525 1526 1527
		if (bdev_free && bdev->bd_write_holder) {
			disk_unblock_events(bdev->bd_disk);
			bdev->bd_write_holder = false;
1528
		}
1529
	}
1530

1531 1532 1533 1534 1535 1536 1537 1538 1539
	/*
	 * 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
1540
	__blkdev_put(bdev, mode, 0);
1541
}
1542 1543
EXPORT_SYMBOL(blkdev_put);

L
Linus Torvalds 已提交
1544 1545 1546
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
1547 1548
	blkdev_put(bdev, filp->f_mode);
	return 0;
L
Linus Torvalds 已提交
1549 1550
}

1551
static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
L
Linus Torvalds 已提交
1552
{
1553 1554
	struct block_device *bdev = I_BDEV(file->f_mapping->host);
	fmode_t mode = file->f_mode;
1555 1556 1557 1558 1559

	/*
	 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
	 * to updated it before every ioctl.
	 */
1560
	if (file->f_flags & O_NDELAY)
1561 1562 1563 1564
		mode |= FMODE_NDELAY;
	else
		mode &= ~FMODE_NDELAY;

1565
	return blkdev_ioctl(bdev, mode, cmd, arg);
L
Linus Torvalds 已提交
1566 1567
}

1568 1569 1570 1571 1572 1573 1574
/*
 * 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.
 */
1575
ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
1576 1577
{
	struct file *file = iocb->ki_filp;
1578
	struct blk_plug plug;
1579 1580
	ssize_t ret;

1581
	blk_start_plug(&plug);
1582
	ret = __generic_file_write_iter(iocb, from);
1583
	if (ret > 0) {
1584
		ssize_t err;
1585
		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
1586
		if (err < 0)
1587 1588
			ret = err;
	}
1589
	blk_finish_plug(&plug);
1590 1591
	return ret;
}
1592
EXPORT_SYMBOL_GPL(blkdev_write_iter);
1593

1594
ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
1595 1596 1597 1598
{
	struct file *file = iocb->ki_filp;
	struct inode *bd_inode = file->f_mapping->host;
	loff_t size = i_size_read(bd_inode);
1599
	loff_t pos = iocb->ki_pos;
1600 1601 1602 1603 1604

	if (pos >= size)
		return 0;

	size -= pos;
1605 1606
	iov_iter_truncate(to, size);
	return generic_file_read_iter(iocb, to);
1607
}
1608
EXPORT_SYMBOL_GPL(blkdev_read_iter);
1609

1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623
/*
 * 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
1624
static const struct address_space_operations def_blk_aops = {
L
Linus Torvalds 已提交
1625
	.readpage	= blkdev_readpage,
1626
	.readpages	= blkdev_readpages,
L
Linus Torvalds 已提交
1627
	.writepage	= blkdev_writepage,
N
Nick Piggin 已提交
1628 1629
	.write_begin	= blkdev_write_begin,
	.write_end	= blkdev_write_end,
L
Linus Torvalds 已提交
1630
	.writepages	= generic_writepages,
1631
	.releasepage	= blkdev_releasepage,
L
Linus Torvalds 已提交
1632
	.direct_IO	= blkdev_direct_IO,
1633
	.is_dirty_writeback = buffer_check_dirty_writeback,
L
Linus Torvalds 已提交
1634 1635
};

1636
const struct file_operations def_blk_fops = {
L
Linus Torvalds 已提交
1637 1638 1639
	.open		= blkdev_open,
	.release	= blkdev_close,
	.llseek		= block_llseek,
1640
	.read		= new_sync_read,
1641
	.write		= new_sync_write,
1642
	.read_iter	= blkdev_read_iter,
1643
	.write_iter	= blkdev_write_iter,
1644
	.mmap		= generic_file_mmap,
1645
	.fsync		= blkdev_fsync,
1646
	.unlocked_ioctl	= block_ioctl,
L
Linus Torvalds 已提交
1647 1648 1649
#ifdef CONFIG_COMPAT
	.compat_ioctl	= compat_blkdev_ioctl,
#endif
1650
	.splice_read	= generic_file_splice_read,
A
Al Viro 已提交
1651
	.splice_write	= iter_file_splice_write,
L
Linus Torvalds 已提交
1652 1653 1654 1655 1656 1657 1658
};

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);
1659
	res = blkdev_ioctl(bdev, 0, cmd, arg);
L
Linus Torvalds 已提交
1660 1661 1662 1663 1664 1665 1666 1667
	set_fs(old_fs);
	return res;
}

EXPORT_SYMBOL(ioctl_by_bdev);

/**
 * lookup_bdev  - lookup a struct block_device by name
1668
 * @pathname:	special file representing the block device
L
Linus Torvalds 已提交
1669
 *
1670
 * Get a reference to the blockdevice at @pathname in the current
L
Linus Torvalds 已提交
1671 1672 1673
 * namespace if possible and return it.  Return ERR_PTR(error)
 * otherwise.
 */
1674
struct block_device *lookup_bdev(const char *pathname)
L
Linus Torvalds 已提交
1675 1676 1677
{
	struct block_device *bdev;
	struct inode *inode;
1678
	struct path path;
L
Linus Torvalds 已提交
1679 1680
	int error;

1681
	if (!pathname || !*pathname)
L
Linus Torvalds 已提交
1682 1683
		return ERR_PTR(-EINVAL);

1684
	error = kern_path(pathname, LOOKUP_FOLLOW, &path);
L
Linus Torvalds 已提交
1685 1686 1687
	if (error)
		return ERR_PTR(error);

1688
	inode = path.dentry->d_inode;
L
Linus Torvalds 已提交
1689 1690 1691 1692
	error = -ENOTBLK;
	if (!S_ISBLK(inode->i_mode))
		goto fail;
	error = -EACCES;
1693
	if (path.mnt->mnt_flags & MNT_NODEV)
L
Linus Torvalds 已提交
1694 1695 1696 1697 1698 1699
		goto fail;
	error = -ENOMEM;
	bdev = bd_acquire(inode);
	if (!bdev)
		goto fail;
out:
1700
	path_put(&path);
L
Linus Torvalds 已提交
1701 1702 1703 1704 1705
	return bdev;
fail:
	bdev = ERR_PTR(error);
	goto out;
}
1706
EXPORT_SYMBOL(lookup_bdev);
L
Linus Torvalds 已提交
1707

1708
int __invalidate_device(struct block_device *bdev, bool kill_dirty)
1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720
{
	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);
1721
		res = invalidate_inodes(sb, kill_dirty);
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		drop_super(sb);
	}
1724
	invalidate_bdev(bdev);
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	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);
}