block_dev.c 37.0 KB
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/*
 *  linux/fs/block_dev.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 2001  Andrea Arcangeli <andrea@suse.de> SuSE
 */

#include <linux/init.h>
#include <linux/mm.h>
#include <linux/fcntl.h>
#include <linux/slab.h>
#include <linux/kmod.h>
#include <linux/major.h>
#include <linux/smp_lock.h>
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#include <linux/device_cgroup.h>
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#include <linux/highmem.h>
#include <linux/blkdev.h>
#include <linux/module.h>
#include <linux/blkpg.h>
#include <linux/buffer_head.h>
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#include <linux/pagevec.h>
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#include <linux/writeback.h>
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#include <linux/mpage.h>
#include <linux/mount.h>
#include <linux/uio.h>
#include <linux/namei.h>
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#include <linux/log2.h>
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#include <linux/kmemleak.h>
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#include <asm/uaccess.h>
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#include "internal.h"
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struct bdev_inode {
	struct block_device bdev;
	struct inode vfs_inode;
};

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static const struct address_space_operations def_blk_aops;

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static inline struct bdev_inode *BDEV_I(struct inode *inode)
{
	return container_of(inode, struct bdev_inode, vfs_inode);
}

inline struct block_device *I_BDEV(struct inode *inode)
{
	return &BDEV_I(inode)->bdev;
}

EXPORT_SYMBOL(I_BDEV);

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/*
 * move the inode from it's current bdi to the 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.
 */
static void bdev_inode_switch_bdi(struct inode *inode,
			struct backing_dev_info *dst)
{
	spin_lock(&inode_lock);
	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_lock);
}

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static sector_t max_block(struct block_device *bdev)
{
	sector_t retval = ~((sector_t)0);
	loff_t sz = i_size_read(bdev->bd_inode);

	if (sz) {
		unsigned int size = block_size(bdev);
		unsigned int sizebits = blksize_bits(size);
		retval = (sz >> sizebits);
	}
	return retval;
}

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/* Kill _all_ buffers and pagecache , dirty or not.. */
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static void kill_bdev(struct block_device *bdev)
{
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	if (bdev->bd_inode->i_mapping->nrpages == 0)
		return;
	invalidate_bh_lrus();
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	truncate_inode_pages(bdev->bd_inode->i_mapping, 0);
}	

int set_blocksize(struct block_device *bdev, int size)
{
	/* Size must be a power of two, and between 512 and PAGE_SIZE */
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	if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
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		return -EINVAL;

	/* Size cannot be smaller than the size supported by the device */
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	if (size < bdev_logical_block_size(bdev))
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		return -EINVAL;

	/* Don't change the size if it is same as current */
	if (bdev->bd_block_size != size) {
		sync_blockdev(bdev);
		bdev->bd_block_size = size;
		bdev->bd_inode->i_blkbits = blksize_bits(size);
		kill_bdev(bdev);
	}
	return 0;
}

EXPORT_SYMBOL(set_blocksize);

int sb_set_blocksize(struct super_block *sb, int size)
{
	if (set_blocksize(sb->s_bdev, size))
		return 0;
	/* If we get here, we know size is power of two
	 * and it's value is between 512 and PAGE_SIZE */
	sb->s_blocksize = size;
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	sb->s_blocksize_bits = blksize_bits(size);
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	return sb->s_blocksize;
}

EXPORT_SYMBOL(sb_set_blocksize);

int sb_min_blocksize(struct super_block *sb, int size)
{
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	int minsize = bdev_logical_block_size(sb->s_bdev);
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	if (size < minsize)
		size = minsize;
	return sb_set_blocksize(sb, size);
}

EXPORT_SYMBOL(sb_min_blocksize);

static int
blkdev_get_block(struct inode *inode, sector_t iblock,
		struct buffer_head *bh, int create)
{
	if (iblock >= max_block(I_BDEV(inode))) {
		if (create)
			return -EIO;

		/*
		 * for reads, we're just trying to fill a partial page.
		 * return a hole, they will have to call get_block again
		 * before they can fill it, and they will get -EIO at that
		 * time
		 */
		return 0;
	}
	bh->b_bdev = I_BDEV(inode);
	bh->b_blocknr = iblock;
	set_buffer_mapped(bh);
	return 0;
}

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static int
blkdev_get_blocks(struct inode *inode, sector_t iblock,
		struct buffer_head *bh, int create)
{
	sector_t end_block = max_block(I_BDEV(inode));
	unsigned long max_blocks = bh->b_size >> inode->i_blkbits;

	if ((iblock + max_blocks) > end_block) {
		max_blocks = end_block - iblock;
		if ((long)max_blocks <= 0) {
			if (create)
				return -EIO;	/* write fully beyond EOF */
			/*
			 * It is a read which is fully beyond EOF.  We return
			 * a !buffer_mapped buffer
			 */
			max_blocks = 0;
		}
	}

	bh->b_bdev = I_BDEV(inode);
	bh->b_blocknr = iblock;
	bh->b_size = max_blocks << inode->i_blkbits;
	if (max_blocks)
		set_buffer_mapped(bh);
	return 0;
}

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

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

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

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

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

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

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

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

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

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

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static int blkdev_write_begin(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned flags,
			struct page **pagep, void **fsdata)
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{
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	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);

	switch (origin) {
		case 2:
			offset += size;
			break;
		case 1:
			offset += file->f_pos;
	}
	retval = -EINVAL;
	if (offset >= 0 && offset <= size) {
		if (offset != file->f_pos) {
			file->f_pos = offset;
		}
		retval = offset;
	}
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	mutex_unlock(&bd_inode->i_mutex);
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	return retval;
}
	
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int blkdev_fsync(struct file *filp, int datasync)
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{
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	struct inode *bd_inode = filp->f_mapping->host;
	struct block_device *bdev = I_BDEV(bd_inode);
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	int error;

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

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

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	return error;
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}
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EXPORT_SYMBOL(blkdev_fsync);
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/*
 * pseudo-fs
 */

static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
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static struct kmem_cache * bdev_cachep __read_mostly;
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static struct inode *bdev_alloc_inode(struct super_block *sb)
{
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	struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
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	if (!ei)
		return NULL;
	return &ei->vfs_inode;
}

static void bdev_destroy_inode(struct inode *inode)
{
	struct bdev_inode *bdi = BDEV_I(inode);

	kmem_cache_free(bdev_cachep, bdi);
}

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static void init_once(void *foo)
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{
	struct bdev_inode *ei = (struct bdev_inode *) foo;
	struct block_device *bdev = &ei->bdev;

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	memset(bdev, 0, sizeof(*bdev));
	mutex_init(&bdev->bd_mutex);
	INIT_LIST_HEAD(&bdev->bd_inodes);
	INIT_LIST_HEAD(&bdev->bd_list);
	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? */
	end_writeback(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, 0x62646576);
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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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struct super_block *blockdev_superblock __read_mostly;
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void __init bdev_cache_init(void)
{
	int err;
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	struct vfsmount *bd_mnt;

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	bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
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			0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
				SLAB_MEM_SPREAD|SLAB_PANIC),
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			init_once);
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	err = register_filesystem(&bd_type);
	if (err)
		panic("Cannot register bdev pseudo-fs");
	bd_mnt = kern_mount(&bd_type);
	if (IS_ERR(bd_mnt))
		panic("Cannot create bdev pseudo-fs");
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	/*
	 * This vfsmount structure is only used to obtain the
	 * blockdev_superblock, so tell kmemleak not to report it.
	 */
	kmemleak_not_leak(bd_mnt);
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	blockdev_superblock = bd_mnt->mnt_sb;	/* For writeback */
}

/*
 * Most likely _very_ bad one - but then it's hardly critical for small
 * /dev and can be fixed when somebody will need really large one.
 * Keep in mind that it will be fed through icache hash function too.
 */
static inline unsigned long hash(dev_t dev)
{
	return MAJOR(dev)+MINOR(dev);
}

static int bdev_test(struct inode *inode, void *data)
{
	return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
}

static int bdev_set(struct inode *inode, void *data)
{
	BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
	return 0;
}

static LIST_HEAD(all_bdevs);

struct block_device *bdget(dev_t dev)
{
	struct block_device *bdev;
	struct inode *inode;

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	inode = iget5_locked(blockdev_superblock, hash(dev),
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			bdev_test, bdev_set, &dev);

	if (!inode)
		return NULL;

	bdev = &BDEV_I(inode)->bdev;

	if (inode->i_state & I_NEW) {
		bdev->bd_contains = NULL;
		bdev->bd_inode = inode;
		bdev->bd_block_size = (1 << inode->i_blkbits);
		bdev->bd_part_count = 0;
		bdev->bd_invalidated = 0;
		inode->i_mode = S_IFBLK;
		inode->i_rdev = dev;
		inode->i_bdev = bdev;
		inode->i_data.a_ops = &def_blk_aops;
		mapping_set_gfp_mask(&inode->i_data, GFP_USER);
		inode->i_data.backing_dev_info = &default_backing_dev_info;
		spin_lock(&bdev_lock);
		list_add(&bdev->bd_list, &all_bdevs);
		spin_unlock(&bdev_lock);
		unlock_new_inode(inode);
	}
	return bdev;
}

EXPORT_SYMBOL(bdget);

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/**
 * bdgrab -- Grab a reference to an already referenced block device
 * @bdev:	Block device to grab a reference to.
 */
struct block_device *bdgrab(struct block_device *bdev)
{
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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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		spin_unlock(&bdev_lock);
		return bdev;
	}
	spin_unlock(&bdev_lock);
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	bdev = bdget(inode->i_rdev);
	if (bdev) {
		spin_lock(&bdev_lock);
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		if (!inode->i_bdev) {
			/*
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			 * We take an additional reference to bd_inode,
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			 * and it's released in clear_inode() of inode.
			 * So, we can access it via ->i_mapping always
			 * without igrab().
			 */
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			ihold(bdev->bd_inode);
612 613 614 615
			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
616 617 618 619 620 621 622 623 624
		spin_unlock(&bdev_lock);
	}
	return bdev;
}

/* Call when you free inode */

void bd_forget(struct inode *inode)
{
625 626
	struct block_device *bdev = NULL;

L
Linus Torvalds 已提交
627
	spin_lock(&bdev_lock);
628
	if (inode->i_bdev) {
629
		if (!sb_is_blkdev_sb(inode->i_sb))
630
			bdev = inode->i_bdev;
L
Linus Torvalds 已提交
631
		__bd_forget(inode);
632
	}
L
Linus Torvalds 已提交
633
	spin_unlock(&bdev_lock);
634 635 636

	if (bdev)
		iput(bdev->bd_inode);
L
Linus Torvalds 已提交
637 638
}

T
Tejun Heo 已提交
639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654
/**
 * bd_may_claim - test whether a block device can be claimed
 * @bdev: block device of interest
 * @whole: whole block device containing @bdev, may equal @bdev
 * @holder: holder trying to claim @bdev
 *
 * Test whther @bdev can be claimed by @holder.
 *
 * CONTEXT:
 * spin_lock(&bdev_lock).
 *
 * RETURNS:
 * %true if @bdev can be claimed, %false otherwise.
 */
static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
			 void *holder)
L
Linus Torvalds 已提交
655 656
{
	if (bdev->bd_holder == holder)
T
Tejun Heo 已提交
657
		return true;	 /* already a holder */
L
Linus Torvalds 已提交
658
	else if (bdev->bd_holder != NULL)
T
Tejun Heo 已提交
659
		return false; 	 /* held by someone else */
L
Linus Torvalds 已提交
660
	else if (bdev->bd_contains == bdev)
T
Tejun Heo 已提交
661
		return true;  	 /* is a whole device which isn't held */
L
Linus Torvalds 已提交
662

663
	else if (whole->bd_holder == bd_may_claim)
T
Tejun Heo 已提交
664 665 666
		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
667
	else
T
Tejun Heo 已提交
668 669 670
		return true;	 /* is a partition of an un-held device */
}

671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696
/**
 * 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;

697 698
	/* if claiming is already in progress, wait for it to finish */
	if (whole->bd_claiming) {
699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721
		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
722 723 724 725 726 727 728
 * 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.
729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754
 *
 * CONTEXT:
 * Might sleep.
 *
 * RETURNS:
 * Pointer to the block device containing @bdev on success, ERR_PTR()
 * value on failure.
 */
static struct block_device *bd_start_claiming(struct block_device *bdev,
					      void *holder)
{
	struct gendisk *disk;
	struct block_device *whole;
	int partno, err;

	might_sleep();

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

	whole = bdget_disk(disk, 0);
755
	module_put(disk->fops->owner);
756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774
	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);
	}
}

775
#ifdef CONFIG_SYSFS
776
static int add_symlink(struct kobject *from, struct kobject *to)
777
{
778
	return sysfs_create_link(from, to, kobject_name(to));
779 780 781 782 783 784 785
}

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

J
Jun'ichi Nomura 已提交
786
/**
787 788 789
 * 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
790
 *
791
 * This functions creates the following sysfs symlinks.
J
Jun'ichi Nomura 已提交
792
 *
793 794
 * - from "slaves" directory of the holder @disk to the claimed @bdev
 * - from "holders" directory of the @bdev to the holder @disk
795
 *
796 797
 * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
 * passed to bd_link_disk_holder(), then:
798
 *
799 800
 *   /sys/block/dm-0/slaves/sda --> /sys/block/sda
 *   /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
801
 *
802 803 804
 * 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.
805
 *
806 807
 * CONTEXT:
 * Might sleep.
808
 *
809 810
 * RETURNS:
 * 0 on success, -errno on failure.
811
 */
812
int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
813
{
814
	int ret = 0;
815

816
	mutex_lock(&bdev->bd_mutex);
J
Jun'ichi Nomura 已提交
817

818
	WARN_ON_ONCE(!bdev->bd_holder || bdev->bd_holder_disk);
819

820 821 822
	/* FIXME: remove the following once add_disk() handles errors */
	if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
		goto out_unlock;
823

824 825 826
	ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
	if (ret)
		goto out_unlock;
827

828 829 830 831 832
	ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
	if (ret) {
		del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
		goto out_unlock;
	}
833

834 835
	bdev->bd_holder_disk = disk;
out_unlock:
836
	mutex_unlock(&bdev->bd_mutex);
837
	return ret;
838
}
839
EXPORT_SYMBOL_GPL(bd_link_disk_holder);
840

841
static void bd_unlink_disk_holder(struct block_device *bdev)
842
{
843
	struct gendisk *disk = bdev->bd_holder_disk;
844

845 846 847 848 849 850
	bdev->bd_holder_disk = NULL;
	if (!disk)
		return;

	del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
	del_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
851
}
852 853 854
#else
static inline void bd_unlink_disk_holder(struct block_device *bdev)
{ }
855 856
#endif

857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882
/**
 * flush_disk - invalidates all buffer-cache entries on a disk
 *
 * @bdev:      struct block device to be flushed
 *
 * Invalidates all buffer-cache entries on a disk. It should be called
 * when a disk has been changed -- either by a media change or online
 * resize.
 */
static void flush_disk(struct block_device *bdev)
{
	if (__invalidate_device(bdev)) {
		char name[BDEVNAME_SIZE] = "";

		if (bdev->bd_disk)
			disk_name(bdev->bd_disk, 0, name);
		printk(KERN_WARNING "VFS: busy inodes on changed media or "
		       "resized disk %s\n", name);
	}

	if (!bdev->bd_disk)
		return;
	if (disk_partitionable(bdev->bd_disk))
		bdev->bd_invalidated = 1;
}

883
/**
884
 * check_disk_size_change - checks for disk size change and adjusts bdev size.
885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904
 * @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);
905
		flush_disk(bdev);
906 907 908 909
	}
}
EXPORT_SYMBOL(check_disk_size_change);

910
/**
911
 * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
912 913 914 915 916 917 918 919
 * @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)
{
920
	struct block_device *bdev;
921 922 923 924 925
	int ret = 0;

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

926 927 928 929 930 931 932 933
	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);
934 935 936 937
	return ret;
}
EXPORT_SYMBOL(revalidate_disk);

L
Linus Torvalds 已提交
938 939 940 941 942 943 944 945 946 947 948 949
/*
 * 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;
950
	const struct block_device_operations *bdops = disk->fops;
L
Linus Torvalds 已提交
951 952 953 954 955 956

	if (!bdops->media_changed)
		return 0;
	if (!bdops->media_changed(bdev->bd_disk))
		return 0;

957
	flush_disk(bdev);
L
Linus Torvalds 已提交
958 959 960 961 962 963 964 965 966
	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)
{
967
	unsigned bsize = bdev_logical_block_size(bdev);
L
Linus Torvalds 已提交
968 969 970 971 972 973 974 975 976 977 978 979

	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
980
static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
981

982 983 984 985 986 987 988
/*
 * bd_mutex locking:
 *
 *  mutex_lock(part->bd_mutex)
 *    mutex_lock_nested(whole->bd_mutex, 1)
 */

989
static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
L
Linus Torvalds 已提交
990 991
{
	struct gendisk *disk;
992
	int ret;
993
	int partno;
994 995
	int perm = 0;

996
	if (mode & FMODE_READ)
997
		perm |= MAY_READ;
998
	if (mode & FMODE_WRITE)
999 1000 1001 1002
		perm |= MAY_WRITE;
	/*
	 * hooks: /n/, see "layering violations".
	 */
1003 1004 1005 1006 1007 1008
	if (!for_part) {
		ret = devcgroup_inode_permission(bdev->bd_inode, perm);
		if (ret != 0) {
			bdput(bdev);
			return ret;
		}
1009
	}
1010

1011
 restart:
T
Tejun Heo 已提交
1012

1013
	ret = -ENXIO;
1014
	disk = get_gendisk(bdev->bd_dev, &partno);
T
Tejun Heo 已提交
1015
	if (!disk)
1016
		goto out;
L
Linus Torvalds 已提交
1017

1018
	mutex_lock_nested(&bdev->bd_mutex, for_part);
L
Linus Torvalds 已提交
1019 1020 1021
	if (!bdev->bd_openers) {
		bdev->bd_disk = disk;
		bdev->bd_contains = bdev;
1022
		if (!partno) {
L
Linus Torvalds 已提交
1023
			struct backing_dev_info *bdi;
1024 1025 1026 1027 1028 1029

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

L
Linus Torvalds 已提交
1030
			if (disk->fops->open) {
1031
				ret = disk->fops->open(bdev, mode);
1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044
				if (ret == -ERESTARTSYS) {
					/* Lost a race with 'disk' being
					 * deleted, try again.
					 * See md.c
					 */
					disk_put_part(bdev->bd_part);
					bdev->bd_part = NULL;
					module_put(disk->fops->owner);
					put_disk(disk);
					bdev->bd_disk = NULL;
					mutex_unlock(&bdev->bd_mutex);
					goto restart;
				}
L
Linus Torvalds 已提交
1045
				if (ret)
T
Tejun Heo 已提交
1046
					goto out_clear;
L
Linus Torvalds 已提交
1047 1048 1049 1050 1051 1052
			}
			if (!bdev->bd_openers) {
				bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
				bdi = blk_get_backing_dev_info(bdev);
				if (bdi == NULL)
					bdi = &default_backing_dev_info;
1053
				bdev_inode_switch_bdi(bdev->bd_inode, bdi);
L
Linus Torvalds 已提交
1054 1055 1056 1057 1058 1059 1060 1061
			}
			if (bdev->bd_invalidated)
				rescan_partitions(disk, bdev);
		} else {
			struct block_device *whole;
			whole = bdget_disk(disk, 0);
			ret = -ENOMEM;
			if (!whole)
T
Tejun Heo 已提交
1062
				goto out_clear;
1063
			BUG_ON(for_part);
1064
			ret = __blkdev_get(whole, mode, 1);
L
Linus Torvalds 已提交
1065
			if (ret)
T
Tejun Heo 已提交
1066
				goto out_clear;
L
Linus Torvalds 已提交
1067
			bdev->bd_contains = whole;
1068 1069
			bdev_inode_switch_bdi(bdev->bd_inode,
				whole->bd_inode->i_data.backing_dev_info);
1070
			bdev->bd_part = disk_get_part(disk, partno);
1071
			if (!(disk->flags & GENHD_FL_UP) ||
1072
			    !bdev->bd_part || !bdev->bd_part->nr_sects) {
L
Linus Torvalds 已提交
1073
				ret = -ENXIO;
T
Tejun Heo 已提交
1074
				goto out_clear;
L
Linus Torvalds 已提交
1075
			}
1076
			bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
L
Linus Torvalds 已提交
1077 1078
		}
	} else {
T
Tejun Heo 已提交
1079
		module_put(disk->fops->owner);
1080
		put_disk(disk);
T
Tejun Heo 已提交
1081
		disk = NULL;
L
Linus Torvalds 已提交
1082 1083
		if (bdev->bd_contains == bdev) {
			if (bdev->bd_disk->fops->open) {
1084
				ret = bdev->bd_disk->fops->open(bdev, mode);
L
Linus Torvalds 已提交
1085
				if (ret)
T
Tejun Heo 已提交
1086
					goto out_unlock_bdev;
L
Linus Torvalds 已提交
1087 1088 1089 1090 1091 1092
			}
			if (bdev->bd_invalidated)
				rescan_partitions(bdev->bd_disk, bdev);
		}
	}
	bdev->bd_openers++;
1093 1094
	if (for_part)
		bdev->bd_part_count++;
1095
	mutex_unlock(&bdev->bd_mutex);
L
Linus Torvalds 已提交
1096 1097
	return 0;

T
Tejun Heo 已提交
1098
 out_clear:
1099
	disk_put_part(bdev->bd_part);
L
Linus Torvalds 已提交
1100
	bdev->bd_disk = NULL;
T
Tejun Heo 已提交
1101
	bdev->bd_part = NULL;
1102
	bdev_inode_switch_bdi(bdev->bd_inode, &default_backing_dev_info);
L
Linus Torvalds 已提交
1103
	if (bdev != bdev->bd_contains)
1104
		__blkdev_put(bdev->bd_contains, mode, 1);
L
Linus Torvalds 已提交
1105
	bdev->bd_contains = NULL;
T
Tejun Heo 已提交
1106
 out_unlock_bdev:
1107
	mutex_unlock(&bdev->bd_mutex);
1108
 out:
T
Tejun Heo 已提交
1109 1110 1111 1112 1113
	if (disk)
		module_put(disk->fops->owner);
	put_disk(disk);
	bdput(bdev);

L
Linus Torvalds 已提交
1114 1115 1116
	return ret;
}

1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135
/**
 * 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.
 */
1136
int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
L
Linus Torvalds 已提交
1137
{
1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152
	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);

1153 1154 1155 1156 1157 1158
	/* __blkdev_get() may alter read only status, check it afterwards */
	if (!res && (mode & FMODE_WRITE) && bdev_read_only(bdev)) {
		__blkdev_put(bdev, mode, 0);
		res = -EACCES;
	}

1159
	if (whole) {
1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183
		/* finish claiming */
		spin_lock(&bdev_lock);

		if (res == 0) {
			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);
		bdput(whole);
1184 1185 1186
	}

	return res;
1187
}
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EXPORT_SYMBOL(blkdev_get);

1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263
/**
 * 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);

	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);

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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;

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	if (filp->f_flags & O_NDELAY)
		filp->f_mode |= FMODE_NDELAY;
	if (filp->f_flags & O_EXCL)
		filp->f_mode |= FMODE_EXCL;
	if ((filp->f_flags & O_ACCMODE) == 3)
		filp->f_mode |= FMODE_WRITE_IOCTL;

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	bdev = bd_acquire(inode);
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	if (bdev == NULL)
		return -ENOMEM;
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	filp->f_mapping = bdev->bd_inode->i_mapping;

1289
	return blkdev_get(bdev, filp->f_mode, filp);
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}

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static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
1293 1294 1295
{
	int ret = 0;
	struct gendisk *disk = bdev->bd_disk;
1296
	struct block_device *victim = NULL;
1297

1298
	mutex_lock_nested(&bdev->bd_mutex, for_part);
1299 1300 1301
	if (for_part)
		bdev->bd_part_count--;

1302
	if (!--bdev->bd_openers) {
1303
		WARN_ON_ONCE(bdev->bd_holders);
1304 1305 1306 1307 1308
		sync_blockdev(bdev);
		kill_bdev(bdev);
	}
	if (bdev->bd_contains == bdev) {
		if (disk->fops->release)
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			ret = disk->fops->release(disk, mode);
1310 1311 1312 1313 1314 1315
	}
	if (!bdev->bd_openers) {
		struct module *owner = disk->fops->owner;

		put_disk(disk);
		module_put(owner);
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Tejun Heo 已提交
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		disk_put_part(bdev->bd_part);
		bdev->bd_part = NULL;
1318
		bdev->bd_disk = NULL;
1319 1320
		bdev_inode_switch_bdi(bdev->bd_inode,
					&default_backing_dev_info);
1321 1322
		if (bdev != bdev->bd_contains)
			victim = bdev->bd_contains;
1323 1324 1325 1326
		bdev->bd_contains = NULL;
	}
	mutex_unlock(&bdev->bd_mutex);
	bdput(bdev);
1327
	if (victim)
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		__blkdev_put(victim, mode, 1);
1329 1330 1331
	return ret;
}

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int blkdev_put(struct block_device *bdev, fmode_t mode)
1333
{
1334
	if (mode & FMODE_EXCL) {
1335 1336 1337 1338 1339 1340 1341
		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.
		 */
1342
		mutex_lock(&bdev->bd_mutex);
1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357
		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);

		/* if this was the last claim, holder link should go too */
		if (bdev_free)
1358
			bd_unlink_disk_holder(bdev);
1359

1360 1361
		mutex_unlock(&bdev->bd_mutex);
	}
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	return __blkdev_put(bdev, mode, 0);
1363
}
1364 1365
EXPORT_SYMBOL(blkdev_put);

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static int blkdev_close(struct inode * inode, struct file * filp)
{
	struct block_device *bdev = I_BDEV(filp->f_mapping->host);
1369

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	return blkdev_put(bdev, filp->f_mode);
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}

1373
static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
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{
1375 1376
	struct block_device *bdev = I_BDEV(file->f_mapping->host);
	fmode_t mode = file->f_mode;
1377 1378 1379 1380 1381

	/*
	 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
	 * to updated it before every ioctl.
	 */
1382
	if (file->f_flags & O_NDELAY)
1383 1384 1385 1386
		mode |= FMODE_NDELAY;
	else
		mode &= ~FMODE_NDELAY;

1387
	return blkdev_ioctl(bdev, mode, cmd, arg);
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}

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
/*
 * Write data to the block device.  Only intended for the block device itself
 * and the raw driver which basically is a fake block device.
 *
 * Does not take i_mutex for the write and thus is not for general purpose
 * use.
 */
ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
			 unsigned long nr_segs, loff_t pos)
{
	struct file *file = iocb->ki_filp;
	ssize_t ret;

	BUG_ON(iocb->ki_pos != pos);

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

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

1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430
/*
 * 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);
}

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Adrian Bunk 已提交
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static const struct address_space_operations def_blk_aops = {
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	.readpage	= blkdev_readpage,
	.writepage	= blkdev_writepage,
	.sync_page	= block_sync_page,
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Nick Piggin 已提交
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	.write_begin	= blkdev_write_begin,
	.write_end	= blkdev_write_end,
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	.writepages	= generic_writepages,
1438
	.releasepage	= blkdev_releasepage,
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	.direct_IO	= blkdev_direct_IO,
};

1442
const struct file_operations def_blk_fops = {
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	.open		= blkdev_open,
	.release	= blkdev_close,
	.llseek		= block_llseek,
1446 1447
	.read		= do_sync_read,
	.write		= do_sync_write,
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Linus Torvalds 已提交
1448
  	.aio_read	= generic_file_aio_read,
1449
	.aio_write	= blkdev_aio_write,
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1450
	.mmap		= generic_file_mmap,
1451
	.fsync		= blkdev_fsync,
1452
	.unlocked_ioctl	= block_ioctl,
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#ifdef CONFIG_COMPAT
	.compat_ioctl	= compat_blkdev_ioctl,
#endif
1456 1457
	.splice_read	= generic_file_splice_read,
	.splice_write	= generic_file_splice_write,
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};

int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
{
	int res;
	mm_segment_t old_fs = get_fs();
	set_fs(KERNEL_DS);
1465
	res = blkdev_ioctl(bdev, 0, cmd, arg);
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	set_fs(old_fs);
	return res;
}

EXPORT_SYMBOL(ioctl_by_bdev);

/**
 * lookup_bdev  - lookup a struct block_device by name
1474
 * @pathname:	special file representing the block device
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 *
1476
 * Get a reference to the blockdevice at @pathname in the current
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 * namespace if possible and return it.  Return ERR_PTR(error)
 * otherwise.
 */
1480
struct block_device *lookup_bdev(const char *pathname)
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{
	struct block_device *bdev;
	struct inode *inode;
1484
	struct path path;
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	int error;

1487
	if (!pathname || !*pathname)
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Linus Torvalds 已提交
1488 1489
		return ERR_PTR(-EINVAL);

1490
	error = kern_path(pathname, LOOKUP_FOLLOW, &path);
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Linus Torvalds 已提交
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	if (error)
		return ERR_PTR(error);

1494
	inode = path.dentry->d_inode;
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	error = -ENOTBLK;
	if (!S_ISBLK(inode->i_mode))
		goto fail;
	error = -EACCES;
1499
	if (path.mnt->mnt_flags & MNT_NODEV)
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1500 1501 1502 1503 1504 1505
		goto fail;
	error = -ENOMEM;
	bdev = bd_acquire(inode);
	if (!bdev)
		goto fail;
out:
1506
	path_put(&path);
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	return bdev;
fail:
	bdev = ERR_PTR(error);
	goto out;
}
1512
EXPORT_SYMBOL(lookup_bdev);
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Linus Torvalds 已提交
1513

1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529
int __invalidate_device(struct block_device *bdev)
{
	struct super_block *sb = get_super(bdev);
	int res = 0;

	if (sb) {
		/*
		 * no need to lock the super, get_super holds the
		 * read mutex so the filesystem cannot go away
		 * under us (->put_super runs with the write lock
		 * hold).
		 */
		shrink_dcache_sb(sb);
		res = invalidate_inodes(sb);
		drop_super(sb);
	}
1530
	invalidate_bdev(bdev);
1531 1532 1533
	return res;
}
EXPORT_SYMBOL(__invalidate_device);