get rid of pointless iov_length() in ->direct_IO()

all callers have iov_length(iter->iov, iter->nr_segs) == iov_iter_count(iter)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 2172314..1d34f45 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -486,9 +486,7 @@
 	struct nfs_direct_req *dreq;
 	struct nfs_lock_context *l_ctx;
 	ssize_t result = -EINVAL;
-	size_t count;
-
-	count = iov_length(iter->iov, iter->nr_segs);
+	size_t count = iov_iter_count(iter);
 	nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
 
 	dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n",
@@ -877,7 +875,7 @@
 	get_dreq(dreq);
 	atomic_inc(&inode->i_dio_count);
 
-	NFS_I(dreq->inode)->write_io += iov_length(iter->iov, iter->nr_segs);
+	NFS_I(dreq->inode)->write_io += iov_iter_count(iter);
 	for (seg = 0; seg < iter->nr_segs; seg++) {
 		const struct iovec *vec = &iter->iov[seg];
 		result = nfs_direct_write_schedule_segment(&desc, vec, pos, uio);
@@ -936,9 +934,7 @@
 	struct nfs_direct_req *dreq;
 	struct nfs_lock_context *l_ctx;
 	loff_t end;
-	size_t count;
-
-	count = iov_length(iter->iov, iter->nr_segs);
+	size_t count = iov_iter_count(iter);
 	end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
 
 	nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);