NFSD: Clean up nfsd_splice_actor()

nfsd_splice_actor() checks that the page being spliced does not
match the previous element in the svc_rqst::rq_pages array. We
believe this is to prevent a double put_page() in cases where the
READ payload is partially contained in the xdr_buf's head buffer.

However, the NFSD READ proc functions no longer place any part of
the READ payload in the head buffer, in order to properly support
NFS/RDMA READ with Write chunks. Therefore, simplify the logic in
nfsd_splice_actor() to remove this unnecessary check.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/vfs.c

@@ -849,17 +849,11 @@ nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
 		  struct splice_desc *sd)
 {
 	struct svc_rqst *rqstp = sd->u.data;
-	struct page **pp = rqstp->rq_next_page;
-	struct page *page = buf->page;
 
-	if (rqstp->rq_res.page_len == 0) {
-		svc_rqst_replace_page(rqstp, page);
+	svc_rqst_replace_page(rqstp, buf->page);
+	if (rqstp->rq_res.page_len == 0)
 		rqstp->rq_res.page_base = buf->offset;
-	} else if (page != pp[-1]) {
-		svc_rqst_replace_page(rqstp, page);
-	}
 	rqstp->rq_res.page_len += sd->len;
-
 	return sd->len;
 }