block_dev.c 36.8 KB
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/*
 *  linux/fs/block_dev.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 2001  Andrea Arcangeli <andrea@suse.de> SuSE
 */

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

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static const struct address_space_operations def_blk_aops;

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

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

EXPORT_SYMBOL(I_BDEV);

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

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

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

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

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

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

EXPORT_SYMBOL(set_blocksize);

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

EXPORT_SYMBOL(sb_set_blocksize);

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

EXPORT_SYMBOL(sb_min_blocksize);

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

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

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

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

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

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

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

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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) {
		int res = fsync_super(sb);
		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
 *
 * This takes the block device bd_mount_sem to make sure no new mounts
 * happen on bdev until thaw_bdev() is called.
 * 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);
	if (bdev->bd_fsfreeze_count > 0) {
		bdev->bd_fsfreeze_count++;
		sb = get_super(bdev);
		mutex_unlock(&bdev->bd_fsfreeze_mutex);
		return sb;
	}
	bdev->bd_fsfreeze_count++;

	down(&bdev->bd_mount_sem);
	sb = get_super(bdev);
	if (sb && !(sb->s_flags & MS_RDONLY)) {
		sb->s_frozen = SB_FREEZE_WRITE;
		smp_wmb();

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		fsync_super(sb);
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		sb->s_frozen = SB_FREEZE_TRANS;
		smp_wmb();

		sync_blockdev(sb->s_bdev);

		if (sb->s_op->freeze_fs) {
			error = sb->s_op->freeze_fs(sb);
			if (error) {
				printk(KERN_ERR
					"VFS:Filesystem freeze failed\n");
				sb->s_frozen = SB_UNFROZEN;
				drop_super(sb);
				up(&bdev->bd_mount_sem);
				bdev->bd_fsfreeze_count--;
				mutex_unlock(&bdev->bd_fsfreeze_mutex);
				return ERR_PTR(error);
			}
		}
	}

	sync_blockdev(bdev);
	mutex_unlock(&bdev->bd_fsfreeze_mutex);

	return sb;	/* thaw_bdev releases s->s_umount and bd_mount_sem */
}
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)
{
	int error = 0;

	mutex_lock(&bdev->bd_fsfreeze_mutex);
	if (!bdev->bd_fsfreeze_count) {
		mutex_unlock(&bdev->bd_fsfreeze_mutex);
		return -EINVAL;
	}

	bdev->bd_fsfreeze_count--;
	if (bdev->bd_fsfreeze_count > 0) {
		if (sb)
			drop_super(sb);
		mutex_unlock(&bdev->bd_fsfreeze_mutex);
		return 0;
	}

	if (sb) {
		BUG_ON(sb->s_bdev != bdev);
		if (!(sb->s_flags & MS_RDONLY)) {
			if (sb->s_op->unfreeze_fs) {
				error = sb->s_op->unfreeze_fs(sb);
				if (error) {
					printk(KERN_ERR
						"VFS:Filesystem thaw failed\n");
					sb->s_frozen = SB_FREEZE_TRANS;
					bdev->bd_fsfreeze_count++;
					mutex_unlock(&bdev->bd_fsfreeze_mutex);
					return error;
				}
			}
			sb->s_frozen = SB_UNFROZEN;
			smp_wmb();
			wake_up(&sb->s_wait_unfrozen);
		}
		drop_super(sb);
	}

	up(&bdev->bd_mount_sem);
	mutex_unlock(&bdev->bd_fsfreeze_mutex);
	return 0;
}
EXPORT_SYMBOL(thaw_bdev);

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

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

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

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

	unlock_page(page);
	page_cache_release(page);

	return ret;
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}

/*
 * private llseek:
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 * for a block special file file->f_path.dentry->d_inode->i_size is zero
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 * so we compute the size by hand (just as in block_read/write above)
 */
static loff_t block_llseek(struct file *file, loff_t offset, int origin)
{
	struct inode *bd_inode = file->f_mapping->host;
	loff_t size;
	loff_t retval;

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

	switch (origin) {
		case 2:
			offset += size;
			break;
		case 1:
			offset += file->f_pos;
	}
	retval = -EINVAL;
	if (offset >= 0 && offset <= size) {
		if (offset != file->f_pos) {
			file->f_pos = offset;
		}
		retval = offset;
	}
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	mutex_unlock(&bd_inode->i_mutex);
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	return retval;
}
	
/*
 *	Filp is never NULL; the only case when ->fsync() is called with
 *	NULL first argument is nfsd_sync_dir() and that's not a directory.
 */
 
static int block_fsync(struct file *filp, struct dentry *dentry, int datasync)
{
	return sync_blockdev(I_BDEV(filp->f_mapping->host));
}

/*
 * 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);

	bdi->bdev.bd_inode_backing_dev_info = NULL;
	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);
	sema_init(&bdev->bd_mount_sem, 1);
	INIT_LIST_HEAD(&bdev->bd_inodes);
	INIT_LIST_HEAD(&bdev->bd_list);
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#ifdef CONFIG_SYSFS
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	INIT_LIST_HEAD(&bdev->bd_holder_list);
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#endif
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	inode_init_once(&ei->vfs_inode);
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	/* Initialize mutex for freeze. */
	mutex_init(&bdev->bd_fsfreeze_mutex);
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}

static inline void __bd_forget(struct inode *inode)
{
	list_del_init(&inode->i_devices);
	inode->i_bdev = NULL;
	inode->i_mapping = &inode->i_data;
}

static void bdev_clear_inode(struct inode *inode)
{
	struct block_device *bdev = &BDEV_I(inode)->bdev;
	struct list_head *p;
	spin_lock(&bdev_lock);
	while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) {
		__bd_forget(list_entry(p, struct inode, i_devices));
	}
	list_del_init(&bdev->bd_list);
	spin_unlock(&bdev_lock);
}

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static const struct super_operations bdev_sops = {
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	.statfs = simple_statfs,
	.alloc_inode = bdev_alloc_inode,
	.destroy_inode = bdev_destroy_inode,
	.drop_inode = generic_delete_inode,
	.clear_inode = bdev_clear_inode,
};

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static int bd_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
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{
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	return get_sb_pseudo(fs_type, "bdev:", &bdev_sops, 0x62646576, mnt);
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}

static struct file_system_type bd_type = {
	.name		= "bdev",
	.get_sb		= bd_get_sb,
	.kill_sb	= kill_anon_super,
};

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struct super_block *blockdev_superblock __read_mostly;
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void __init bdev_cache_init(void)
{
	int err;
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	struct vfsmount *bd_mnt;

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

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

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

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

static LIST_HEAD(all_bdevs);

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

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

	if (!inode)
		return NULL;

	bdev = &BDEV_I(inode)->bdev;

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

EXPORT_SYMBOL(bdget);

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

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

EXPORT_SYMBOL(bdput);
 
static struct block_device *bd_acquire(struct inode *inode)
{
	struct block_device *bdev;
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	spin_lock(&bdev_lock);
	bdev = inode->i_bdev;
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	if (bdev) {
		atomic_inc(&bdev->bd_inode->i_count);
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		spin_unlock(&bdev_lock);
		return bdev;
	}
	spin_unlock(&bdev_lock);
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	bdev = bdget(inode->i_rdev);
	if (bdev) {
		spin_lock(&bdev_lock);
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		if (!inode->i_bdev) {
			/*
			 * We take an additional bd_inode->i_count for inode,
			 * and it's released in clear_inode() of inode.
			 * So, we can access it via ->i_mapping always
			 * without igrab().
			 */
			atomic_inc(&bdev->bd_inode->i_count);
			inode->i_bdev = bdev;
			inode->i_mapping = bdev->bd_inode->i_mapping;
			list_add(&inode->i_devices, &bdev->bd_inodes);
		}
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		spin_unlock(&bdev_lock);
	}
	return bdev;
}

/* Call when you free inode */

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

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

	if (bdev)
		iput(bdev->bd_inode);
L
Linus Torvalds 已提交
635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685
}

int bd_claim(struct block_device *bdev, void *holder)
{
	int res;
	spin_lock(&bdev_lock);

	/* first decide result */
	if (bdev->bd_holder == holder)
		res = 0;	 /* already a holder */
	else if (bdev->bd_holder != NULL)
		res = -EBUSY; 	 /* held by someone else */
	else if (bdev->bd_contains == bdev)
		res = 0;  	 /* is a whole device which isn't held */

	else if (bdev->bd_contains->bd_holder == bd_claim)
		res = 0; 	 /* is a partition of a device that is being partitioned */
	else if (bdev->bd_contains->bd_holder != NULL)
		res = -EBUSY;	 /* is a partition of a held device */
	else
		res = 0;	 /* is a partition of an un-held device */

	/* now impose change */
	if (res==0) {
		/* note that for a whole device bd_holders
		 * will be incremented twice, and bd_holder will
		 * be set to bd_claim before being set to holder
		 */
		bdev->bd_contains->bd_holders ++;
		bdev->bd_contains->bd_holder = bd_claim;
		bdev->bd_holders++;
		bdev->bd_holder = holder;
	}
	spin_unlock(&bdev_lock);
	return res;
}

EXPORT_SYMBOL(bd_claim);

void bd_release(struct block_device *bdev)
{
	spin_lock(&bdev_lock);
	if (!--bdev->bd_contains->bd_holders)
		bdev->bd_contains->bd_holder = NULL;
	if (!--bdev->bd_holders)
		bdev->bd_holder = NULL;
	spin_unlock(&bdev_lock);
}

EXPORT_SYMBOL(bd_release);

686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703
#ifdef CONFIG_SYSFS
/*
 * Functions for bd_claim_by_kobject / bd_release_from_kobject
 *
 *     If a kobject is passed to bd_claim_by_kobject()
 *     and the kobject has a parent directory,
 *     following symlinks are created:
 *        o from the kobject to the claimed bdev
 *        o from "holders" directory of the bdev to the parent of the kobject
 *     bd_release_from_kobject() removes these symlinks.
 *
 *     Example:
 *        If /dev/dm-0 maps to /dev/sda, kobject corresponding to
 *        /sys/block/dm-0/slaves is passed to bd_claim_by_kobject(), then:
 *           /sys/block/dm-0/slaves/sda --> /sys/block/sda
 *           /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
 */

704
static int add_symlink(struct kobject *from, struct kobject *to)
705 706
{
	if (!from || !to)
707 708
		return 0;
	return sysfs_create_link(from, to, kobject_name(to));
709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751
}

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

/*
 * 'struct bd_holder' contains pointers to kobjects symlinked by
 * bd_claim_by_kobject.
 * It's connected to bd_holder_list which is protected by bdev->bd_sem.
 */
struct bd_holder {
	struct list_head list;	/* chain of holders of the bdev */
	int count;		/* references from the holder */
	struct kobject *sdir;	/* holder object, e.g. "/block/dm-0/slaves" */
	struct kobject *hdev;	/* e.g. "/block/dm-0" */
	struct kobject *hdir;	/* e.g. "/block/sda/holders" */
	struct kobject *sdev;	/* e.g. "/block/sda" */
};

/*
 * Get references of related kobjects at once.
 * Returns 1 on success. 0 on failure.
 *
 * Should call bd_holder_release_dirs() after successful use.
 */
static int bd_holder_grab_dirs(struct block_device *bdev,
			struct bd_holder *bo)
{
	if (!bdev || !bo)
		return 0;

	bo->sdir = kobject_get(bo->sdir);
	if (!bo->sdir)
		return 0;

	bo->hdev = kobject_get(bo->sdir->parent);
	if (!bo->hdev)
		goto fail_put_sdir;

T
Tejun Heo 已提交
752
	bo->sdev = kobject_get(&part_to_dev(bdev->bd_part)->kobj);
753 754 755
	if (!bo->sdev)
		goto fail_put_hdev;

756
	bo->hdir = kobject_get(bdev->bd_part->holder_dir);
757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799
	if (!bo->hdir)
		goto fail_put_sdev;

	return 1;

fail_put_sdev:
	kobject_put(bo->sdev);
fail_put_hdev:
	kobject_put(bo->hdev);
fail_put_sdir:
	kobject_put(bo->sdir);

	return 0;
}

/* Put references of related kobjects at once. */
static void bd_holder_release_dirs(struct bd_holder *bo)
{
	kobject_put(bo->hdir);
	kobject_put(bo->sdev);
	kobject_put(bo->hdev);
	kobject_put(bo->sdir);
}

static struct bd_holder *alloc_bd_holder(struct kobject *kobj)
{
	struct bd_holder *bo;

	bo = kzalloc(sizeof(*bo), GFP_KERNEL);
	if (!bo)
		return NULL;

	bo->count = 1;
	bo->sdir = kobj;

	return bo;
}

static void free_bd_holder(struct bd_holder *bo)
{
	kfree(bo);
}

J
Jun'ichi Nomura 已提交
800 801 802 803 804 805 806 807 808 809
/**
 * find_bd_holder - find matching struct bd_holder from the block device
 *
 * @bdev:	struct block device to be searched
 * @bo:		target struct bd_holder
 *
 * Returns matching entry with @bo in @bdev->bd_holder_list.
 * If found, increment the reference count and return the pointer.
 * If not found, returns NULL.
 */
A
Andrew Morton 已提交
810 811
static struct bd_holder *find_bd_holder(struct block_device *bdev,
					struct bd_holder *bo)
J
Jun'ichi Nomura 已提交
812 813 814 815 816 817 818 819 820 821 822 823
{
	struct bd_holder *tmp;

	list_for_each_entry(tmp, &bdev->bd_holder_list, list)
		if (tmp->sdir == bo->sdir) {
			tmp->count++;
			return tmp;
		}

	return NULL;
}

824 825 826 827 828 829
/**
 * add_bd_holder - create sysfs symlinks for bd_claim() relationship
 *
 * @bdev:	block device to be bd_claimed
 * @bo:		preallocated and initialized by alloc_bd_holder()
 *
J
Jun'ichi Nomura 已提交
830
 * Add @bo to @bdev->bd_holder_list, create symlinks.
831
 *
J
Jun'ichi Nomura 已提交
832 833
 * Returns 0 if symlinks are created.
 * Returns -ve if something fails.
834 835 836
 */
static int add_bd_holder(struct block_device *bdev, struct bd_holder *bo)
{
837
	int err;
838 839

	if (!bo)
840
		return -EINVAL;
841 842

	if (!bd_holder_grab_dirs(bdev, bo))
843
		return -EBUSY;
844

845 846 847 848 849 850 851 852
	err = add_symlink(bo->sdir, bo->sdev);
	if (err)
		return err;

	err = add_symlink(bo->hdir, bo->hdev);
	if (err) {
		del_symlink(bo->sdir, bo->sdev);
		return err;
853
	}
854 855 856

	list_add_tail(&bo->list, &bdev->bd_holder_list);
	return 0;
857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913
}

/**
 * del_bd_holder - delete sysfs symlinks for bd_claim() relationship
 *
 * @bdev:	block device to be bd_claimed
 * @kobj:	holder's kobject
 *
 * If there is matching entry with @kobj in @bdev->bd_holder_list
 * and no other bd_claim() from the same kobject,
 * remove the struct bd_holder from the list, delete symlinks for it.
 *
 * Returns a pointer to the struct bd_holder when it's removed from the list
 * and ready to be freed.
 * Returns NULL if matching claim isn't found or there is other bd_claim()
 * by the same kobject.
 */
static struct bd_holder *del_bd_holder(struct block_device *bdev,
					struct kobject *kobj)
{
	struct bd_holder *bo;

	list_for_each_entry(bo, &bdev->bd_holder_list, list) {
		if (bo->sdir == kobj) {
			bo->count--;
			BUG_ON(bo->count < 0);
			if (!bo->count) {
				list_del(&bo->list);
				del_symlink(bo->sdir, bo->sdev);
				del_symlink(bo->hdir, bo->hdev);
				bd_holder_release_dirs(bo);
				return bo;
			}
			break;
		}
	}

	return NULL;
}

/**
 * bd_claim_by_kobject - bd_claim() with additional kobject signature
 *
 * @bdev:	block device to be claimed
 * @holder:	holder's signature
 * @kobj:	holder's kobject
 *
 * Do bd_claim() and if it succeeds, create sysfs symlinks between
 * the bdev and the holder's kobject.
 * Use bd_release_from_kobject() when relesing the claimed bdev.
 *
 * Returns 0 on success. (same as bd_claim())
 * Returns errno on failure.
 */
static int bd_claim_by_kobject(struct block_device *bdev, void *holder,
				struct kobject *kobj)
{
914
	int err;
J
Jun'ichi Nomura 已提交
915
	struct bd_holder *bo, *found;
916 917 918 919 920 921 922 923

	if (!kobj)
		return -EINVAL;

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

924
	mutex_lock(&bdev->bd_mutex);
J
Jun'ichi Nomura 已提交
925

926 927
	err = bd_claim(bdev, holder);
	if (err)
A
Andrew Morton 已提交
928
		goto fail;
929 930 931

	found = find_bd_holder(bdev, bo);
	if (found)
A
Andrew Morton 已提交
932
		goto fail;
933 934 935 936

	err = add_bd_holder(bdev, bo);
	if (err)
		bd_release(bdev);
A
Andrew Morton 已提交
937 938 939
	else
		bo = NULL;
fail:
940
	mutex_unlock(&bdev->bd_mutex);
A
Andrew Morton 已提交
941
	free_bd_holder(bo);
942
	return err;
943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958
}

/**
 * bd_release_from_kobject - bd_release() with additional kobject signature
 *
 * @bdev:	block device to be released
 * @kobj:	holder's kobject
 *
 * Do bd_release() and remove sysfs symlinks created by bd_claim_by_kobject().
 */
static void bd_release_from_kobject(struct block_device *bdev,
					struct kobject *kobj)
{
	if (!kobj)
		return;

959
	mutex_lock(&bdev->bd_mutex);
960
	bd_release(bdev);
A
Andrew Morton 已提交
961
	free_bd_holder(del_bd_holder(bdev, kobj));
962
	mutex_unlock(&bdev->bd_mutex);
963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996
}

/**
 * bd_claim_by_disk - wrapper function for bd_claim_by_kobject()
 *
 * @bdev:	block device to be claimed
 * @holder:	holder's signature
 * @disk:	holder's gendisk
 *
 * Call bd_claim_by_kobject() with getting @disk->slave_dir.
 */
int bd_claim_by_disk(struct block_device *bdev, void *holder,
			struct gendisk *disk)
{
	return bd_claim_by_kobject(bdev, holder, kobject_get(disk->slave_dir));
}
EXPORT_SYMBOL_GPL(bd_claim_by_disk);

/**
 * bd_release_from_disk - wrapper function for bd_release_from_kobject()
 *
 * @bdev:	block device to be claimed
 * @disk:	holder's gendisk
 *
 * Call bd_release_from_kobject() and put @disk->slave_dir.
 */
void bd_release_from_disk(struct block_device *bdev, struct gendisk *disk)
{
	bd_release_from_kobject(bdev, disk->slave_dir);
	kobject_put(disk->slave_dir);
}
EXPORT_SYMBOL_GPL(bd_release_from_disk);
#endif

L
Linus Torvalds 已提交
997 998 999 1000 1001 1002 1003
/*
 * Tries to open block device by device number.  Use it ONLY if you
 * really do not have anything better - i.e. when you are behind a
 * truly sucky interface and all you are given is a device number.  _Never_
 * to be used for internal purposes.  If you ever need it - reconsider
 * your API.
 */
1004
struct block_device *open_by_devnum(dev_t dev, fmode_t mode)
L
Linus Torvalds 已提交
1005 1006 1007 1008
{
	struct block_device *bdev = bdget(dev);
	int err = -ENOMEM;
	if (bdev)
1009
		err = blkdev_get(bdev, mode);
L
Linus Torvalds 已提交
1010 1011 1012 1013 1014
	return err ? ERR_PTR(err) : bdev;
}

EXPORT_SYMBOL(open_by_devnum);

1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040
/**
 * 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;
}

1041
/**
1042
 * check_disk_size_change - checks for disk size change and adjusts bdev size.
1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062
 * @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);
1063
		flush_disk(bdev);
1064 1065 1066 1067
	}
}
EXPORT_SYMBOL(check_disk_size_change);

1068
/**
1069
 * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
1070 1071 1072 1073 1074 1075 1076 1077
 * @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)
{
1078
	struct block_device *bdev;
1079 1080 1081 1082 1083
	int ret = 0;

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

1084 1085 1086 1087 1088 1089 1090 1091
	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);
1092 1093 1094 1095
	return ret;
}
EXPORT_SYMBOL(revalidate_disk);

L
Linus Torvalds 已提交
1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114
/*
 * 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;
	struct block_device_operations * bdops = disk->fops;

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

1115
	flush_disk(bdev);
L
Linus Torvalds 已提交
1116 1117 1118 1119 1120 1121 1122 1123 1124
	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)
{
1125
	unsigned bsize = bdev_logical_block_size(bdev);
L
Linus Torvalds 已提交
1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137

	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
1138
static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
1139

1140 1141 1142 1143 1144 1145 1146
/*
 * bd_mutex locking:
 *
 *  mutex_lock(part->bd_mutex)
 *    mutex_lock_nested(whole->bd_mutex, 1)
 */

1147
static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
L
Linus Torvalds 已提交
1148 1149
{
	struct gendisk *disk;
1150
	int ret;
1151
	int partno;
1152 1153
	int perm = 0;

1154
	if (mode & FMODE_READ)
1155
		perm |= MAY_READ;
1156
	if (mode & FMODE_WRITE)
1157 1158 1159 1160 1161
		perm |= MAY_WRITE;
	/*
	 * hooks: /n/, see "layering violations".
	 */
	ret = devcgroup_inode_permission(bdev->bd_inode, perm);
1162 1163
	if (ret != 0) {
		bdput(bdev);
1164
		return ret;
1165
	}
1166

L
Linus Torvalds 已提交
1167
	lock_kernel();
1168
 restart:
T
Tejun Heo 已提交
1169

1170
	ret = -ENXIO;
1171
	disk = get_gendisk(bdev->bd_dev, &partno);
T
Tejun Heo 已提交
1172 1173
	if (!disk)
		goto out_unlock_kernel;
L
Linus Torvalds 已提交
1174

1175
	mutex_lock_nested(&bdev->bd_mutex, for_part);
L
Linus Torvalds 已提交
1176 1177 1178
	if (!bdev->bd_openers) {
		bdev->bd_disk = disk;
		bdev->bd_contains = bdev;
1179
		if (!partno) {
L
Linus Torvalds 已提交
1180
			struct backing_dev_info *bdi;
1181 1182 1183 1184 1185 1186

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

L
Linus Torvalds 已提交
1187
			if (disk->fops->open) {
1188
				ret = disk->fops->open(bdev, mode);
1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201
				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
1202
				if (ret)
T
Tejun Heo 已提交
1203
					goto out_clear;
L
Linus Torvalds 已提交
1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218
			}
			if (!bdev->bd_openers) {
				bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
				bdi = blk_get_backing_dev_info(bdev);
				if (bdi == NULL)
					bdi = &default_backing_dev_info;
				bdev->bd_inode->i_data.backing_dev_info = bdi;
			}
			if (bdev->bd_invalidated)
				rescan_partitions(disk, bdev);
		} else {
			struct block_device *whole;
			whole = bdget_disk(disk, 0);
			ret = -ENOMEM;
			if (!whole)
T
Tejun Heo 已提交
1219
				goto out_clear;
1220
			BUG_ON(for_part);
1221
			ret = __blkdev_get(whole, mode, 1);
L
Linus Torvalds 已提交
1222
			if (ret)
T
Tejun Heo 已提交
1223
				goto out_clear;
L
Linus Torvalds 已提交
1224 1225 1226
			bdev->bd_contains = whole;
			bdev->bd_inode->i_data.backing_dev_info =
			   whole->bd_inode->i_data.backing_dev_info;
1227
			bdev->bd_part = disk_get_part(disk, partno);
1228
			if (!(disk->flags & GENHD_FL_UP) ||
1229
			    !bdev->bd_part || !bdev->bd_part->nr_sects) {
L
Linus Torvalds 已提交
1230
				ret = -ENXIO;
T
Tejun Heo 已提交
1231
				goto out_clear;
L
Linus Torvalds 已提交
1232
			}
1233
			bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
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		}
	} else {
		put_disk(disk);
T
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		module_put(disk->fops->owner);
		disk = NULL;
L
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		if (bdev->bd_contains == bdev) {
			if (bdev->bd_disk->fops->open) {
1241
				ret = bdev->bd_disk->fops->open(bdev, mode);
L
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1242
				if (ret)
T
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					goto out_unlock_bdev;
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1244 1245 1246 1247 1248 1249
			}
			if (bdev->bd_invalidated)
				rescan_partitions(bdev->bd_disk, bdev);
		}
	}
	bdev->bd_openers++;
1250 1251
	if (for_part)
		bdev->bd_part_count++;
1252
	mutex_unlock(&bdev->bd_mutex);
L
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1253 1254 1255
	unlock_kernel();
	return 0;

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 out_clear:
1257
	disk_put_part(bdev->bd_part);
L
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1258
	bdev->bd_disk = NULL;
T
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	bdev->bd_part = NULL;
L
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	bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
	if (bdev != bdev->bd_contains)
1262
		__blkdev_put(bdev->bd_contains, mode, 1);
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	bdev->bd_contains = NULL;
T
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1264
 out_unlock_bdev:
1265
	mutex_unlock(&bdev->bd_mutex);
T
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1266
 out_unlock_kernel:
L
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1267
	unlock_kernel();
T
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1268 1269 1270 1271 1272 1273

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

L
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	return ret;
}

1277
int blkdev_get(struct block_device *bdev, fmode_t mode)
L
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{
1279
	return __blkdev_get(bdev, mode, 0);
1280
}
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EXPORT_SYMBOL(blkdev_get);

static int blkdev_open(struct inode * inode, struct file * filp)
{
	struct block_device *bdev;
	int res;

	/*
	 * Preserve backwards compatibility and allow large file access
	 * even if userspace doesn't ask for it explicitly. Some mkfs
	 * binary needs it. We might want to drop this workaround
	 * during an unstable branch.
	 */
	filp->f_flags |= O_LARGEFILE;

1296 1297 1298 1299 1300 1301 1302
	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);
1304 1305
	if (bdev == NULL)
		return -ENOMEM;
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Linus Torvalds 已提交
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1307 1308 1309
	filp->f_mapping = bdev->bd_inode->i_mapping;

	res = blkdev_get(bdev, filp->f_mode);
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1310 1311 1312
	if (res)
		return res;

1313 1314 1315 1316 1317
	if (filp->f_mode & FMODE_EXCL) {
		res = bd_claim(bdev, filp);
		if (res)
			goto out_blkdev_put;
	}
L
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1318

1319
	return 0;
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1320

1321
 out_blkdev_put:
A
Al Viro 已提交
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	blkdev_put(bdev, filp->f_mode);
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	return res;
}

A
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1326
static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
1327 1328 1329
{
	int ret = 0;
	struct gendisk *disk = bdev->bd_disk;
1330
	struct block_device *victim = NULL;
1331

1332
	mutex_lock_nested(&bdev->bd_mutex, for_part);
1333
	lock_kernel();
1334 1335 1336
	if (for_part)
		bdev->bd_part_count--;

1337 1338 1339 1340 1341 1342
	if (!--bdev->bd_openers) {
		sync_blockdev(bdev);
		kill_bdev(bdev);
	}
	if (bdev->bd_contains == bdev) {
		if (disk->fops->release)
A
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			ret = disk->fops->release(disk, mode);
1344 1345 1346 1347 1348 1349
	}
	if (!bdev->bd_openers) {
		struct module *owner = disk->fops->owner;

		put_disk(disk);
		module_put(owner);
T
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		disk_put_part(bdev->bd_part);
		bdev->bd_part = NULL;
1352 1353
		bdev->bd_disk = NULL;
		bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
1354 1355
		if (bdev != bdev->bd_contains)
			victim = bdev->bd_contains;
1356 1357 1358 1359 1360
		bdev->bd_contains = NULL;
	}
	unlock_kernel();
	mutex_unlock(&bdev->bd_mutex);
	bdput(bdev);
1361
	if (victim)
A
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		__blkdev_put(victim, mode, 1);
1363 1364 1365
	return ret;
}

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int blkdev_put(struct block_device *bdev, fmode_t mode)
1367
{
A
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	return __blkdev_put(bdev, mode, 0);
1369
}
1370 1371
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);
	if (bdev->bd_holder == filp)
		bd_release(bdev);
A
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	return blkdev_put(bdev, filp->f_mode);
L
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1378 1379
}

1380
static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
L
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1381
{
1382 1383
	struct block_device *bdev = I_BDEV(file->f_mapping->host);
	fmode_t mode = file->f_mode;
1384 1385 1386 1387 1388

	/*
	 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
	 * to updated it before every ioctl.
	 */
1389
	if (file->f_flags & O_NDELAY)
1390 1391 1392 1393
		mode |= FMODE_NDELAY;
	else
		mode &= ~FMODE_NDELAY;

1394
	return blkdev_ioctl(bdev, mode, cmd, arg);
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}

1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410
/*
 * 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 = {
L
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1412 1413 1414
	.readpage	= blkdev_readpage,
	.writepage	= blkdev_writepage,
	.sync_page	= block_sync_page,
N
Nick Piggin 已提交
1415 1416
	.write_begin	= blkdev_write_begin,
	.write_end	= blkdev_write_end,
L
Linus Torvalds 已提交
1417
	.writepages	= generic_writepages,
1418
	.releasepage	= blkdev_releasepage,
L
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	.direct_IO	= blkdev_direct_IO,
};

1422
const struct file_operations def_blk_fops = {
L
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1423 1424 1425
	.open		= blkdev_open,
	.release	= blkdev_close,
	.llseek		= block_llseek,
1426 1427
	.read		= do_sync_read,
	.write		= do_sync_write,
L
Linus Torvalds 已提交
1428
  	.aio_read	= generic_file_aio_read,
1429
  	.aio_write	= generic_file_aio_write_nolock,
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	.mmap		= generic_file_mmap,
	.fsync		= block_fsync,
1432
	.unlocked_ioctl	= block_ioctl,
L
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#ifdef CONFIG_COMPAT
	.compat_ioctl	= compat_blkdev_ioctl,
#endif
1436 1437
	.splice_read	= generic_file_splice_read,
	.splice_write	= generic_file_splice_write,
L
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1438 1439 1440 1441 1442 1443 1444
};

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);
1445
	res = blkdev_ioctl(bdev, 0, cmd, arg);
L
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	set_fs(old_fs);
	return res;
}

EXPORT_SYMBOL(ioctl_by_bdev);

/**
 * lookup_bdev  - lookup a struct block_device by name
1454
 * @pathname:	special file representing the block device
L
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1455
 *
1456
 * Get a reference to the blockdevice at @pathname in the current
L
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1457 1458 1459
 * namespace if possible and return it.  Return ERR_PTR(error)
 * otherwise.
 */
1460
struct block_device *lookup_bdev(const char *pathname)
L
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1461 1462 1463
{
	struct block_device *bdev;
	struct inode *inode;
1464
	struct path path;
L
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1465 1466
	int error;

1467
	if (!pathname || !*pathname)
L
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1468 1469
		return ERR_PTR(-EINVAL);

1470
	error = kern_path(pathname, LOOKUP_FOLLOW, &path);
L
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1471 1472 1473
	if (error)
		return ERR_PTR(error);

1474
	inode = path.dentry->d_inode;
L
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1475 1476 1477 1478
	error = -ENOTBLK;
	if (!S_ISBLK(inode->i_mode))
		goto fail;
	error = -EACCES;
1479
	if (path.mnt->mnt_flags & MNT_NODEV)
L
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1480 1481 1482 1483 1484 1485
		goto fail;
	error = -ENOMEM;
	bdev = bd_acquire(inode);
	if (!bdev)
		goto fail;
out:
1486
	path_put(&path);
L
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1487 1488 1489 1490 1491
	return bdev;
fail:
	bdev = ERR_PTR(error);
	goto out;
}
1492
EXPORT_SYMBOL(lookup_bdev);
L
Linus Torvalds 已提交
1493 1494

/**
1495
 * open_bdev_exclusive  -  open a block device by name and set it up for use
L
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1496 1497
 *
 * @path:	special file representing the block device
1498
 * @mode:	FMODE_... combination to pass be used
L
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1499 1500 1501 1502 1503
 * @holder:	owner for exclusion
 *
 * Open the blockdevice described by the special file at @path, claim it
 * for the @holder.
 */
1504
struct block_device *open_bdev_exclusive(const char *path, fmode_t mode, void *holder)
L
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1505 1506 1507 1508 1509 1510 1511 1512
{
	struct block_device *bdev;
	int error = 0;

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

1513
	error = blkdev_get(bdev, mode);
L
Linus Torvalds 已提交
1514 1515 1516
	if (error)
		return ERR_PTR(error);
	error = -EACCES;
1517
	if ((mode & FMODE_WRITE) && bdev_read_only(bdev))
L
Linus Torvalds 已提交
1518 1519 1520 1521 1522 1523 1524 1525
		goto blkdev_put;
	error = bd_claim(bdev, holder);
	if (error)
		goto blkdev_put;

	return bdev;
	
blkdev_put:
A
Al Viro 已提交
1526
	blkdev_put(bdev, mode);
L
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1527 1528 1529
	return ERR_PTR(error);
}

1530
EXPORT_SYMBOL(open_bdev_exclusive);
L
Linus Torvalds 已提交
1531 1532

/**
1533
 * close_bdev_exclusive  -  close a blockdevice opened by open_bdev_exclusive()
L
Linus Torvalds 已提交
1534 1535
 *
 * @bdev:	blockdevice to close
1536
 * @mode:	mode, must match that used to open.
L
Linus Torvalds 已提交
1537
 *
1538
 * This is the counterpart to open_bdev_exclusive().
L
Linus Torvalds 已提交
1539
 */
1540
void close_bdev_exclusive(struct block_device *bdev, fmode_t mode)
L
Linus Torvalds 已提交
1541 1542
{
	bd_release(bdev);
1543
	blkdev_put(bdev, mode);
L
Linus Torvalds 已提交
1544 1545
}

1546
EXPORT_SYMBOL(close_bdev_exclusive);
1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563

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);
	}
1564
	invalidate_bdev(bdev);
1565 1566 1567
	return res;
}
EXPORT_SYMBOL(__invalidate_device);