[patch 08/11] Hook up compat XFS_IOC_ATTRLIST_BY_HANDLE ioctl handler

[Christoph Hellwig]

On Tue, Nov 18, 2008 at 10:44:09PM -0600, sandeen at sandeen.net wrote:
> +/*
> + * Convert userspace handle data into inode.
> + *
> + * We use the fact that all the fsop_handlereq ioctl calls have a data
> + * structure argument whose first component is always a xfs_fsop_handlereq_t,
> + * so we can pass that sub structure into this handy, shared routine.
> + *
> + * If no error, caller must always iput the returned inode.
> + */
> +STATIC int
> +xfs_vget_fsop_handlereq_compat(
> +	xfs_mount_t		*mp,
> +	struct inode		*parinode,	/* parent inode pointer    */
> +	compat_xfs_fsop_handlereq_t	*hreq,
> +	struct inode		**inode)
> +{
> +	void			__user *hanp;
> +	size_t			hlen;
> +	xfs_fid_t		*xfid;
> +	xfs_handle_t		*handlep;
> +	xfs_handle_t		handle;
> +	xfs_inode_t		*ip;
> +	xfs_ino_t		ino;
> +	__u32			igen;
> +	int			error;
> +
> +	/*
> +	 * Only allow handle opens under a directory.
> +	 */
> +	if (!S_ISDIR(parinode->i_mode))
> +		return XFS_ERROR(ENOTDIR);
> +
> +	hanp = compat_ptr(hreq->ihandle);
> +	hlen = hreq->ihandlen;
> +	handlep = &handle;
> +
> +	if (hlen < sizeof(handlep->ha_fsid) || hlen > sizeof(*handlep))
> +		return XFS_ERROR(EINVAL);
> +	if (copy_from_user(handlep, hanp, hlen))
> +		return XFS_ERROR(EFAULT);
> +	if (hlen < sizeof(*handlep))
> +		memset(((char *)handlep) + hlen, 0, sizeof(*handlep) - hlen);
> +	if (hlen > sizeof(handlep->ha_fsid)) {
> +		if (handlep->ha_fid.fid_len !=
> +		    (hlen - sizeof(handlep->ha_fsid) -
> +		            sizeof(handlep->ha_fid.fid_len)) ||
> +		    handlep->ha_fid.fid_pad)
> +			return XFS_ERROR(EINVAL);
> +	}
> +
> +	/*
> +	 * Crack the handle, obtain the inode # & generation #
> +	 */
> +	xfid = (struct xfs_fid *)&handlep->ha_fid;
> +	if (xfid->fid_len == sizeof(*xfid) - sizeof(xfid->fid_len)) {
> +		ino  = xfid->fid_ino;
> +		igen = xfid->fid_gen;
> +	} else {
> +		return XFS_ERROR(EINVAL);
> +	}
> +
> +	/*
> +	 * Get the XFS inode, building a Linux inode to go with it.
> +	 */
> +	error = xfs_iget(mp, NULL, ino, 0, XFS_ILOCK_SHARED, &ip, 0);
> +	if (error)
> +		return error;
> +	if (ip == NULL)
> +		return XFS_ERROR(EIO);
> +	if (ip->i_d.di_gen != igen) {
> +		xfs_iput_new(ip, XFS_ILOCK_SHARED);
> +		return XFS_ERROR(ENOENT);
> +	}
> +
> +	xfs_iunlock(ip, XFS_ILOCK_SHARED);
> +
> +	*inode = VFS_I(ip);
> +	return 0;

Not really a big fan of duplicating this, at least the second half could
be factored out into a common helper for native and compat handle ops,
dmapi and nfs exporting.  But I think this is fine for now, I have some
bigger plans for this area anyway.

So ACK for this patch.