staging/lustre/libcfs: Copy correct amount in libcfs_ioctl_getdata

Commit b8ff756bc351 ("staging: lustre: libcfs: merge code from
libcfs_ioctl into libcfs_ioctl_getdata") introduced a problem
copying just a single pointer worth of data from userspace
instead of whole libcfs_ioctl_hdr structure.
Adjust the copying amount.
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Acked-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lnet/libcfs/linux/linux-module.c

@@ -128,7 +128,7 @@ int libcfs_ioctl_getdata(struct libcfs_ioctl_hdr **hdr_pp,
 	struct libcfs_ioctl_hdr hdr;
 	int err = 0;
 
-	if (copy_from_user(&hdr, uhdr, sizeof(uhdr)))
+	if (copy_from_user(&hdr, uhdr, sizeof(hdr)))
 		return -EFAULT;
 
 	if (hdr.ioc_version != LIBCFS_IOCTL_VERSION &&