anon-inodes use open coded atomic_inc for the shared inode

{

	struct qstr this;

	struct dentry *dentry;

	struct inode *inode;

	struct file *file;

	int error, fd;

	if (!file)

		return -ENFILE;

	inode = igrab(anon_inode_inode);

	if (IS_ERR(inode)) {

		error = PTR_ERR(inode);

		goto err_put_filp;

	}

	error = get_unused_fd();

	if (error < 0)

		goto err_iput;

		goto err_put_filp;

	fd = error;

	/*

	dentry = d_alloc(anon_inode_mnt->mnt_sb->s_root, &this);

	if (!dentry)

		goto err_put_unused_fd;

	/*

	 * We know the anon_inode inode count is always greater than zero,

	 * so we can avoid doing an igrab() and we can use an open-coded

	 * atomic_inc().

	 */

	atomic_inc(&anon_inode_inode->i_count);

	dentry->d_op = &anon_inodefs_dentry_operations;

	/* Do not publish this dentry inside the global dentry hash table */

	dentry->d_flags &= ~DCACHE_UNHASHED;

	d_instantiate(dentry, inode);

	d_instantiate(dentry, anon_inode_inode);

	file->f_path.mnt = mntget(anon_inode_mnt);

	file->f_path.dentry = dentry;

	file->f_mapping = inode->i_mapping;

	file->f_mapping = anon_inode_inode->i_mapping;

	file->f_pos = 0;

	file->f_flags = O_RDWR;

	fd_install(fd, file);

	*pfd = fd;

	*pinode = inode;

	*pinode = anon_inode_inode;

	*pfile = file;

	return 0;

err_put_unused_fd:

	put_unused_fd(fd);

err_iput:

	iput(inode);

err_put_filp:

	put_filp(file);

	return error;