block_dev.c 41.5 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 <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. If the inode is dirty we
 * need to move it onto the dirty list of @dst so that the inode is always on
 * the right list.
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 */
static void bdev_inode_switch_bdi(struct inode *inode,
			struct backing_dev_info *dst)
{
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	struct backing_dev_info *old = inode->i_data.backing_dev_info;

	if (unlikely(dst == old))		/* deadlock avoidance */
		return;
	bdi_lock_two(&old->wb, &dst->wb);
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	spin_lock(&inode->i_lock);
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	inode->i_data.backing_dev_info = dst;
	if (inode->i_state & I_DIRTY)
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		list_move(&inode->i_wb_list, &dst->wb.b_dirty);
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	spin_unlock(&inode->i_lock);
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	spin_unlock(&old->wb.list_lock);
	spin_unlock(&dst->wb.list_lock);
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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;

	if (mapping->nrpages == 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
blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
			loff_t offset, unsigned long nr_segs)
{
	struct file *file = iocb->ki_filp;
	struct inode *inode = file->f_mapping->host;

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

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

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

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

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

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

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

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static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
{
	return block_write_full_page(page, blkdev_get_block, wbc);
}

static int blkdev_readpage(struct file * file, struct page * page)
{
	return block_read_full_page(page, blkdev_get_block);
}

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static int blkdev_write_begin(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned flags,
			struct page **pagep, void **fsdata)
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{
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	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->f_path.dentry->d_inode->i_size is zero
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 * so we compute the size by hand (just as in block_read/write above)
 */
static loff_t block_llseek(struct file *file, loff_t offset, int origin)
{
	struct inode *bd_inode = file->f_mapping->host;
	loff_t size;
	loff_t retval;

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	mutex_lock(&bd_inode->i_mutex);
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	size = i_size_read(bd_inode);

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	retval = -EINVAL;
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	switch (origin) {
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		case SEEK_END:
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			offset += size;
			break;
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		case SEEK_CUR:
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			offset += file->f_pos;
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		case SEEK_SET:
			break;
		default:
			goto out;
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	}
	if (offset >= 0 && offset <= size) {
		if (offset != file->f_pos) {
			file->f_pos = offset;
		}
		retval = offset;
	}
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out:
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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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/*
 * 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(&inode->i_data, 0);
	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);

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

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long nr_blockdev_pages(void)
{
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	struct block_device *bdev;
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	long ret = 0;
	spin_lock(&bdev_lock);
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	list_for_each_entry(bdev, &all_bdevs, bd_list) {
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		ret += bdev->bd_inode->i_mapping->nrpages;
	}
	spin_unlock(&bdev_lock);
	return ret;
}

void bdput(struct block_device *bdev)
{
	iput(bdev->bd_inode);
}

EXPORT_SYMBOL(bdput);
 
static struct block_device *bd_acquire(struct inode *inode)
{
	struct block_device *bdev;
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	spin_lock(&bdev_lock);
	bdev = inode->i_bdev;
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	if (bdev) {
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		ihold(bdev->bd_inode);
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582 583 584 585
		spin_unlock(&bdev_lock);
		return bdev;
	}
	spin_unlock(&bdev_lock);
586

L
Linus Torvalds 已提交
587 588 589
	bdev = bdget(inode->i_rdev);
	if (bdev) {
		spin_lock(&bdev_lock);
590 591
		if (!inode->i_bdev) {
			/*
A
Al Viro 已提交
592
			 * We take an additional reference to bd_inode,
593 594 595 596
			 * 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
597
			ihold(bdev->bd_inode);
598 599 600 601
			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
602 603 604 605 606
		spin_unlock(&bdev_lock);
	}
	return bdev;
}

A
Al Viro 已提交
607 608 609 610 611
static inline int sb_is_blkdev_sb(struct super_block *sb)
{
	return sb == blockdev_superblock;
}

L
Linus Torvalds 已提交
612 613 614 615
/* Call when you free inode */

void bd_forget(struct inode *inode)
{
616 617
	struct block_device *bdev = NULL;

L
Linus Torvalds 已提交
618
	spin_lock(&bdev_lock);
619
	if (inode->i_bdev) {
620
		if (!sb_is_blkdev_sb(inode->i_sb))
621
			bdev = inode->i_bdev;
L
Linus Torvalds 已提交
622
		__bd_forget(inode);
623
	}
L
Linus Torvalds 已提交
624
	spin_unlock(&bdev_lock);
625 626 627

	if (bdev)
		iput(bdev->bd_inode);
L
Linus Torvalds 已提交
628 629
}

T
Tejun Heo 已提交
630 631 632 633 634 635
/**
 * 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
636
 * Test whether @bdev can be claimed by @holder.
T
Tejun Heo 已提交
637 638 639 640 641 642 643 644 645
 *
 * 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
646 647
{
	if (bdev->bd_holder == holder)
T
Tejun Heo 已提交
648
		return true;	 /* already a holder */
L
Linus Torvalds 已提交
649
	else if (bdev->bd_holder != NULL)
T
Tejun Heo 已提交
650
		return false; 	 /* held by someone else */
L
Linus Torvalds 已提交
651
	else if (bdev->bd_contains == bdev)
T
Tejun Heo 已提交
652
		return true;  	 /* is a whole device which isn't held */
L
Linus Torvalds 已提交
653

654
	else if (whole->bd_holder == bd_may_claim)
T
Tejun Heo 已提交
655 656 657
		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
658
	else
T
Tejun Heo 已提交
659 660 661
		return true;	 /* is a partition of an un-held device */
}

662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687
/**
 * 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;

688 689
	/* if claiming is already in progress, wait for it to finish */
	if (whole->bd_claiming) {
690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712
		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
713 714 715 716 717 718 719
 * 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.
720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744
 *
 * 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);

745 746 747 748 749 750 751 752 753 754 755 756 757
	/*
	 * 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);

758
	module_put(disk->fops->owner);
759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777
	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);
	}
}

778
#ifdef CONFIG_SYSFS
779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795
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;
}

796
static int add_symlink(struct kobject *from, struct kobject *to)
797
{
798
	return sysfs_create_link(from, to, kobject_name(to));
799 800 801 802 803 804 805
}

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

J
Jun'ichi Nomura 已提交
806
/**
807 808 809
 * 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
810
 *
811 812
 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
 *
813
 * This functions creates the following sysfs symlinks.
814
 *
815 816
 * - from "slaves" directory of the holder @disk to the claimed @bdev
 * - from "holders" directory of the @bdev to the holder @disk
817
 *
818 819
 * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
 * passed to bd_link_disk_holder(), then:
820
 *
821 822
 *   /sys/block/dm-0/slaves/sda --> /sys/block/sda
 *   /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
823
 *
824 825 826
 * 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.
827
 *
828 829
 * CONTEXT:
 * Might sleep.
830
 *
831 832
 * RETURNS:
 * 0 on success, -errno on failure.
833
 */
834
int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
835
{
836
	struct bd_holder_disk *holder;
837
	int ret = 0;
838

839
	mutex_lock(&bdev->bd_mutex);
J
Jun'ichi Nomura 已提交
840

841
	WARN_ON_ONCE(!bdev->bd_holder);
842

843 844 845
	/* FIXME: remove the following once add_disk() handles errors */
	if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
		goto out_unlock;
846

847 848 849
	holder = bd_find_holder_disk(bdev, disk);
	if (holder) {
		holder->refcnt++;
850
		goto out_unlock;
851
	}
852

853 854 855
	holder = kzalloc(sizeof(*holder), GFP_KERNEL);
	if (!holder) {
		ret = -ENOMEM;
856 857
		goto out_unlock;
	}
858

859 860 861 862 863 864 865 866 867 868 869
	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;
870 871 872 873 874
	/*
	 * bdev could be deleted beneath us which would implicitly destroy
	 * the holder directory.  Hold on to it.
	 */
	kobject_get(bdev->bd_part->holder_dir);
875 876 877 878 879 880 881 882

	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);
883
out_unlock:
884
	mutex_unlock(&bdev->bd_mutex);
885
	return ret;
886
}
887
EXPORT_SYMBOL_GPL(bd_link_disk_holder);
888

889 890 891 892 893 894 895 896 897 898 899
/**
 * 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)
900
{
901
	struct bd_holder_disk *holder;
902

903
	mutex_lock(&bdev->bd_mutex);
904

905 906 907 908 909 910
	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);
911
		kobject_put(bdev->bd_part->holder_dir);
912 913 914 915 916
		list_del_init(&holder->list);
		kfree(holder);
	}

	mutex_unlock(&bdev->bd_mutex);
L
Linus Torvalds 已提交
917
}
918
EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
919
#endif
L
Linus Torvalds 已提交
920

921 922 923 924
/**
 * flush_disk - invalidates all buffer-cache entries on a disk
 *
 * @bdev:      struct block device to be flushed
925
 * @kill_dirty: flag to guide handling of dirty inodes
926 927 928 929 930
 *
 * 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.
 */
931
static void flush_disk(struct block_device *bdev, bool kill_dirty)
932
{
933
	if (__invalidate_device(bdev, kill_dirty)) {
934 935 936 937 938 939 940 941 942 943
		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
944
	if (disk_part_scan_enabled(bdev->bd_disk))
945 946 947
		bdev->bd_invalidated = 1;
}

948
/**
949
 * check_disk_size_change - checks for disk size change and adjusts bdev size.
950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969
 * @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);
970
		flush_disk(bdev, false);
971 972 973 974
	}
}
EXPORT_SYMBOL(check_disk_size_change);

975
/**
976
 * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
977 978 979 980 981 982 983 984
 * @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)
{
985
	struct block_device *bdev;
986 987 988 989 990
	int ret = 0;

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

991 992 993 994 995 996 997 998
	bdev = bdget_disk(disk, 0);
	if (!bdev)
		return ret;

	mutex_lock(&bdev->bd_mutex);
	check_disk_size_change(disk, bdev);
	mutex_unlock(&bdev->bd_mutex);
	bdput(bdev);
999 1000 1001 1002
	return ret;
}
EXPORT_SYMBOL(revalidate_disk);

L
Linus Torvalds 已提交
1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014
/*
 * 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;
1015
	const struct block_device_operations *bdops = disk->fops;
1016
	unsigned int events;
L
Linus Torvalds 已提交
1017

1018 1019 1020
	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
1021 1022
		return 0;

1023
	flush_disk(bdev, true);
L
Linus Torvalds 已提交
1024 1025 1026 1027 1028 1029 1030 1031 1032
	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)
{
1033
	unsigned bsize = bdev_logical_block_size(bdev);
L
Linus Torvalds 已提交
1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045

	bdev->bd_inode->i_size = size;
	while (bsize < PAGE_CACHE_SIZE) {
		if (size & bsize)
			break;
		bsize <<= 1;
	}
	bdev->bd_block_size = bsize;
	bdev->bd_inode->i_blkbits = blksize_bits(bsize);
}
EXPORT_SYMBOL(bd_set_size);

A
Al Viro 已提交
1046
static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
1047

1048 1049 1050 1051 1052 1053 1054
/*
 * bd_mutex locking:
 *
 *  mutex_lock(part->bd_mutex)
 *    mutex_lock_nested(whole->bd_mutex, 1)
 */

1055
static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
L
Linus Torvalds 已提交
1056 1057
{
	struct gendisk *disk;
1058
	struct module *owner;
1059
	int ret;
1060
	int partno;
1061 1062
	int perm = 0;

1063
	if (mode & FMODE_READ)
1064
		perm |= MAY_READ;
1065
	if (mode & FMODE_WRITE)
1066 1067 1068 1069
		perm |= MAY_WRITE;
	/*
	 * hooks: /n/, see "layering violations".
	 */
1070 1071 1072 1073 1074 1075
	if (!for_part) {
		ret = devcgroup_inode_permission(bdev->bd_inode, perm);
		if (ret != 0) {
			bdput(bdev);
			return ret;
		}
1076
	}
1077

1078
 restart:
T
Tejun Heo 已提交
1079

1080
	ret = -ENXIO;
1081
	disk = get_gendisk(bdev->bd_dev, &partno);
T
Tejun Heo 已提交
1082
	if (!disk)
1083
		goto out;
1084
	owner = disk->fops->owner;
L
Linus Torvalds 已提交
1085

1086
	disk_block_events(disk);
1087
	mutex_lock_nested(&bdev->bd_mutex, for_part);
L
Linus Torvalds 已提交
1088 1089
	if (!bdev->bd_openers) {
		bdev->bd_disk = disk;
1090
		bdev->bd_queue = disk->queue;
L
Linus Torvalds 已提交
1091
		bdev->bd_contains = bdev;
1092
		if (!partno) {
L
Linus Torvalds 已提交
1093
			struct backing_dev_info *bdi;
1094 1095 1096 1097 1098 1099

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

1100
			ret = 0;
L
Linus Torvalds 已提交
1101
			if (disk->fops->open) {
1102
				ret = disk->fops->open(bdev, mode);
1103 1104 1105 1106 1107 1108 1109 1110
				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;
1111
					bdev->bd_queue = NULL;
1112
					mutex_unlock(&bdev->bd_mutex);
1113 1114
					disk_unblock_events(disk);
					put_disk(disk);
1115
					module_put(owner);
1116 1117
					goto restart;
				}
L
Linus Torvalds 已提交
1118
			}
1119 1120 1121 1122 1123 1124 1125 1126 1127

			if (!ret && !bdev->bd_openers) {
				bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
				bdi = blk_get_backing_dev_info(bdev);
				if (bdi == NULL)
					bdi = &default_backing_dev_info;
				bdev_inode_switch_bdi(bdev->bd_inode, bdi);
			}

1128 1129 1130 1131 1132 1133
			/*
			 * 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.
			 */
1134 1135 1136 1137 1138 1139
			if (bdev->bd_invalidated) {
				if (!ret)
					rescan_partitions(disk, bdev);
				else if (ret == -ENOMEDIUM)
					invalidate_partitions(disk, bdev);
			}
1140 1141
			if (ret)
				goto out_clear;
L
Linus Torvalds 已提交
1142 1143 1144 1145 1146
		} else {
			struct block_device *whole;
			whole = bdget_disk(disk, 0);
			ret = -ENOMEM;
			if (!whole)
T
Tejun Heo 已提交
1147
				goto out_clear;
1148
			BUG_ON(for_part);
1149
			ret = __blkdev_get(whole, mode, 1);
L
Linus Torvalds 已提交
1150
			if (ret)
T
Tejun Heo 已提交
1151
				goto out_clear;
L
Linus Torvalds 已提交
1152
			bdev->bd_contains = whole;
1153 1154
			bdev_inode_switch_bdi(bdev->bd_inode,
				whole->bd_inode->i_data.backing_dev_info);
1155
			bdev->bd_part = disk_get_part(disk, partno);
1156
			if (!(disk->flags & GENHD_FL_UP) ||
1157
			    !bdev->bd_part || !bdev->bd_part->nr_sects) {
L
Linus Torvalds 已提交
1158
				ret = -ENXIO;
T
Tejun Heo 已提交
1159
				goto out_clear;
L
Linus Torvalds 已提交
1160
			}
1161
			bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
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		}
	} else {
		if (bdev->bd_contains == bdev) {
1165 1166
			ret = 0;
			if (bdev->bd_disk->fops->open)
1167
				ret = bdev->bd_disk->fops->open(bdev, mode);
1168
			/* the same as first opener case, read comment there */
1169 1170 1171 1172 1173 1174
			if (bdev->bd_invalidated) {
				if (!ret)
					rescan_partitions(bdev->bd_disk, bdev);
				else if (ret == -ENOMEDIUM)
					invalidate_partitions(bdev->bd_disk, bdev);
			}
1175 1176
			if (ret)
				goto out_unlock_bdev;
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		}
1178 1179
		/* only one opener holds refs to the module and disk */
		put_disk(disk);
1180
		module_put(owner);
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	}
	bdev->bd_openers++;
1183 1184
	if (for_part)
		bdev->bd_part_count++;
1185
	mutex_unlock(&bdev->bd_mutex);
1186
	disk_unblock_events(disk);
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	return 0;

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 out_clear:
1190
	disk_put_part(bdev->bd_part);
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	bdev->bd_disk = NULL;
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	bdev->bd_part = NULL;
1193
	bdev->bd_queue = NULL;
1194
	bdev_inode_switch_bdi(bdev->bd_inode, &default_backing_dev_info);
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	if (bdev != bdev->bd_contains)
1196
		__blkdev_put(bdev->bd_contains, mode, 1);
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	bdev->bd_contains = NULL;
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 out_unlock_bdev:
1199
	mutex_unlock(&bdev->bd_mutex);
1200
	disk_unblock_events(disk);
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	put_disk(disk);
1202
	module_put(owner);
1203
 out:
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	bdput(bdev);

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	return ret;
}

1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227
/**
 * 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.
 */
1228
int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
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{
1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245
	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) {
1246 1247
		struct gendisk *disk = whole->bd_disk;

1248
		/* finish claiming */
1249
		mutex_lock(&bdev->bd_mutex);
1250 1251
		spin_lock(&bdev_lock);

1252
		if (!res) {
1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271
			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);
1272 1273

		/*
1274 1275 1276 1277 1278
		 * 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().
1279
		 */
1280 1281
		if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder &&
		    (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
1282
			bdev->bd_write_holder = true;
1283
			disk_block_events(disk);
1284 1285 1286
		}

		mutex_unlock(&bdev->bd_mutex);
1287
		bdput(whole);
1288 1289 1290
	}

	return res;
1291
}
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EXPORT_SYMBOL(blkdev_get);

1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324
/**
 * 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);

1325 1326 1327 1328 1329
	if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) {
		blkdev_put(bdev, mode);
		return ERR_PTR(-EACCES);
	}

1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 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 1372
	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
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1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384
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;

1385 1386 1387 1388 1389 1390 1391
	if (filp->f_flags & O_NDELAY)
		filp->f_mode |= FMODE_NDELAY;
	if (filp->f_flags & O_EXCL)
		filp->f_mode |= FMODE_EXCL;
	if ((filp->f_flags & O_ACCMODE) == 3)
		filp->f_mode |= FMODE_WRITE_IOCTL;

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1392
	bdev = bd_acquire(inode);
1393 1394
	if (bdev == NULL)
		return -ENOMEM;
L
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1395

1396 1397
	filp->f_mapping = bdev->bd_inode->i_mapping;

1398
	return blkdev_get(bdev, filp->f_mode, filp);
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1399 1400
}

A
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static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
1402 1403 1404
{
	int ret = 0;
	struct gendisk *disk = bdev->bd_disk;
1405
	struct block_device *victim = NULL;
1406

1407
	mutex_lock_nested(&bdev->bd_mutex, for_part);
1408 1409 1410
	if (for_part)
		bdev->bd_part_count--;

1411
	if (!--bdev->bd_openers) {
1412
		WARN_ON_ONCE(bdev->bd_holders);
1413 1414
		sync_blockdev(bdev);
		kill_bdev(bdev);
1415 1416 1417 1418 1419
		/* ->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);
1420 1421 1422
	}
	if (bdev->bd_contains == bdev) {
		if (disk->fops->release)
A
Al Viro 已提交
1423
			ret = disk->fops->release(disk, mode);
1424 1425 1426 1427
	}
	if (!bdev->bd_openers) {
		struct module *owner = disk->fops->owner;

T
Tejun Heo 已提交
1428 1429
		disk_put_part(bdev->bd_part);
		bdev->bd_part = NULL;
1430
		bdev->bd_disk = NULL;
1431 1432
		if (bdev != bdev->bd_contains)
			victim = bdev->bd_contains;
1433
		bdev->bd_contains = NULL;
1434 1435 1436

		put_disk(disk);
		module_put(owner);
1437 1438 1439
	}
	mutex_unlock(&bdev->bd_mutex);
	bdput(bdev);
1440
	if (victim)
A
Al Viro 已提交
1441
		__blkdev_put(victim, mode, 1);
1442 1443 1444
	return ret;
}

A
Al Viro 已提交
1445
int blkdev_put(struct block_device *bdev, fmode_t mode)
1446
{
1447 1448
	mutex_lock(&bdev->bd_mutex);

1449
	if (mode & FMODE_EXCL) {
1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469
		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);

1470 1471 1472 1473
		/*
		 * If this was the last claim, remove holder link and
		 * unblock evpoll if it was a write holder.
		 */
1474 1475 1476
		if (bdev_free && bdev->bd_write_holder) {
			disk_unblock_events(bdev->bd_disk);
			bdev->bd_write_holder = false;
1477
		}
1478
	}
1479

1480 1481 1482 1483 1484 1485 1486 1487 1488
	/*
	 * 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
1489
	return __blkdev_put(bdev, mode, 0);
1490
}
1491 1492
EXPORT_SYMBOL(blkdev_put);

L
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1493 1494 1495
static int blkdev_close(struct inode * inode, struct file * filp)
{
	struct block_device *bdev = I_BDEV(filp->f_mapping->host);
1496

A
Al Viro 已提交
1497
	return blkdev_put(bdev, filp->f_mode);
L
Linus Torvalds 已提交
1498 1499
}

1500
static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
L
Linus Torvalds 已提交
1501
{
1502 1503
	struct block_device *bdev = I_BDEV(file->f_mapping->host);
	fmode_t mode = file->f_mode;
1504 1505 1506 1507 1508

	/*
	 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
	 * to updated it before every ioctl.
	 */
1509
	if (file->f_flags & O_NDELAY)
1510 1511 1512 1513
		mode |= FMODE_NDELAY;
	else
		mode &= ~FMODE_NDELAY;

1514
	return blkdev_ioctl(bdev, mode, cmd, arg);
L
Linus Torvalds 已提交
1515 1516
}

1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527
/*
 * Write data to the block device.  Only intended for the block device itself
 * and the raw driver which basically is a fake block device.
 *
 * Does not take i_mutex for the write and thus is not for general purpose
 * use.
 */
ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
			 unsigned long nr_segs, loff_t pos)
{
	struct file *file = iocb->ki_filp;
1528
	struct blk_plug plug;
1529 1530 1531 1532
	ssize_t ret;

	BUG_ON(iocb->ki_pos != pos);

1533
	blk_start_plug(&plug);
1534 1535 1536 1537 1538 1539 1540 1541
	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
	if (ret > 0 || ret == -EIOCBQUEUED) {
		ssize_t err;

		err = generic_write_sync(file, pos, ret);
		if (err < 0 && ret > 0)
			ret = err;
	}
1542
	blk_finish_plug(&plug);
1543 1544 1545 1546
	return ret;
}
EXPORT_SYMBOL_GPL(blkdev_aio_write);

1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560
/*
 * 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
1561
static const struct address_space_operations def_blk_aops = {
L
Linus Torvalds 已提交
1562 1563
	.readpage	= blkdev_readpage,
	.writepage	= blkdev_writepage,
N
Nick Piggin 已提交
1564 1565
	.write_begin	= blkdev_write_begin,
	.write_end	= blkdev_write_end,
L
Linus Torvalds 已提交
1566
	.writepages	= generic_writepages,
1567
	.releasepage	= blkdev_releasepage,
L
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1568 1569 1570
	.direct_IO	= blkdev_direct_IO,
};

1571
const struct file_operations def_blk_fops = {
L
Linus Torvalds 已提交
1572 1573 1574
	.open		= blkdev_open,
	.release	= blkdev_close,
	.llseek		= block_llseek,
1575 1576
	.read		= do_sync_read,
	.write		= do_sync_write,
1577
	.aio_read	= generic_file_aio_read,
1578
	.aio_write	= blkdev_aio_write,
1579
	.mmap		= generic_file_mmap,
1580
	.fsync		= blkdev_fsync,
1581
	.unlocked_ioctl	= block_ioctl,
L
Linus Torvalds 已提交
1582 1583 1584
#ifdef CONFIG_COMPAT
	.compat_ioctl	= compat_blkdev_ioctl,
#endif
1585 1586
	.splice_read	= generic_file_splice_read,
	.splice_write	= generic_file_splice_write,
L
Linus Torvalds 已提交
1587 1588 1589 1590 1591 1592 1593
};

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);
1594
	res = blkdev_ioctl(bdev, 0, cmd, arg);
L
Linus Torvalds 已提交
1595 1596 1597 1598 1599 1600 1601 1602
	set_fs(old_fs);
	return res;
}

EXPORT_SYMBOL(ioctl_by_bdev);

/**
 * lookup_bdev  - lookup a struct block_device by name
1603
 * @pathname:	special file representing the block device
L
Linus Torvalds 已提交
1604
 *
1605
 * Get a reference to the blockdevice at @pathname in the current
L
Linus Torvalds 已提交
1606 1607 1608
 * namespace if possible and return it.  Return ERR_PTR(error)
 * otherwise.
 */
1609
struct block_device *lookup_bdev(const char *pathname)
L
Linus Torvalds 已提交
1610 1611 1612
{
	struct block_device *bdev;
	struct inode *inode;
1613
	struct path path;
L
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1614 1615
	int error;

1616
	if (!pathname || !*pathname)
L
Linus Torvalds 已提交
1617 1618
		return ERR_PTR(-EINVAL);

1619
	error = kern_path(pathname, LOOKUP_FOLLOW, &path);
L
Linus Torvalds 已提交
1620 1621 1622
	if (error)
		return ERR_PTR(error);

1623
	inode = path.dentry->d_inode;
L
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1624 1625 1626 1627
	error = -ENOTBLK;
	if (!S_ISBLK(inode->i_mode))
		goto fail;
	error = -EACCES;
1628
	if (path.mnt->mnt_flags & MNT_NODEV)
L
Linus Torvalds 已提交
1629 1630 1631 1632 1633 1634
		goto fail;
	error = -ENOMEM;
	bdev = bd_acquire(inode);
	if (!bdev)
		goto fail;
out:
1635
	path_put(&path);
L
Linus Torvalds 已提交
1636 1637 1638 1639 1640
	return bdev;
fail:
	bdev = ERR_PTR(error);
	goto out;
}
1641
EXPORT_SYMBOL(lookup_bdev);
L
Linus Torvalds 已提交
1642

1643
int __invalidate_device(struct block_device *bdev, bool kill_dirty)
1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655
{
	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);
1656
		res = invalidate_inodes(sb, kill_dirty);
1657 1658
		drop_super(sb);
	}
1659
	invalidate_bdev(bdev);
1660 1661 1662
	return res;
}
EXPORT_SYMBOL(__invalidate_device);
1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698

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);
}