NFS: Clean up - simplify nfs_lock_request()

We only have two places where we need to grab a reference when trying
to lock the nfs_page. We're better off making that explicit.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Fred Isaman <iisaman@netapp.com>

fs/nfs/direct.c

@@ -657,6 +657,7 @@ static ssize_t nfs_direct_write_schedule_segment(struct nfs_pageio_descriptor *d
 				break;
 			}
 			nfs_lock_request(req);
+			kref_get(&req->wb_kref);
 			req->wb_index = pos >> PAGE_SHIFT;
 			req->wb_offset = pos & ~PAGE_MASK;
 			if (!nfs_pageio_add_request(desc, req)) {