From dccb580624d4107139d69c24d83370c61cc16f14 Mon Sep 17 00:00:00 2001
From: Rick Macklem <rmacklem@FreeBSD.org>
Date: Sat, 4 Jul 2020 03:28:13 +0000
Subject: [PATCH] Add support for ext_pgs mbufs to nfscl_reqstart() and
 nfsm_set().

This is another in the series of commits that add support to the NFS client
and server for building RPC messages in ext_pgs mbufs with anonymous pages.
This is useful so that the entire mbuf list does not need to be
copied before calling sosend() when NFS over TLS is enabled.

Since ND_EXTPG is never set yet, there is no semantic change at this time.
---
 sys/fs/nfs/nfs_commonsubs.c | 53 +++++++++++++++++++++++++++++++------
 1 file changed, 45 insertions(+), 8 deletions(-)

diff --git a/sys/fs/nfs/nfs_commonsubs.c b/sys/fs/nfs/nfs_commonsubs.c
index 40ab539a8835..b810096e73a9 100644
--- a/sys/fs/nfs/nfs_commonsubs.c
+++ b/sys/fs/nfs/nfs_commonsubs.c
@@ -359,13 +359,19 @@ nfscl_reqstart(struct nfsrv_descript *nd, int procnum, struct nfsmount *nmp,
 	/*
 	 * Get the first mbuf for the request.
 	 */
-	if (nfs_bigrequest[procnum])
-		NFSMCLGET(mb, M_WAITOK);
-	else
-		NFSMGET(mb);
-	mb->m_len = 0;
-	nd->nd_mreq = nd->nd_mb = mb;
-	nd->nd_bpos = mtod(mb, char *);
+	if ((nd->nd_flag & ND_EXTPG) != 0) {
+		mb = mb_alloc_ext_plus_pages(PAGE_SIZE, M_WAITOK);
+		nd->nd_mreq = nd->nd_mb = mb;
+		nfsm_set(nd, 0);
+	} else {
+		if (nfs_bigrequest[procnum])
+			NFSMCLGET(mb, M_WAITOK);
+		else
+			NFSMGET(mb);
+		mb->m_len = 0;
+		nd->nd_mreq = nd->nd_mb = mb;
+		nd->nd_bpos = mtod(mb, char *);
+	}
 	
 	/*
 	 * And fill the first file handle into the request.
@@ -4804,7 +4810,38 @@ void
 nfsm_set(struct nfsrv_descript *nd, u_int offs)
 {
 	struct mbuf *m;
+	int rlen;
 
 	m = nd->nd_mb;
-	nd->nd_bpos = mtod(m, char *) + offs;
+	if ((m->m_flags & M_EXTPG) != 0) {
+		nd->nd_bextpg = 0;
+		while (offs > 0) {
+			if (nd->nd_bextpg == 0)
+				rlen = m_epg_pagelen(m, 0, m->m_epg_1st_off);
+			else
+				rlen = m_epg_pagelen(m, nd->nd_bextpg, 0);
+			if (offs <= rlen)
+				break;
+			offs -= rlen;
+			nd->nd_bextpg++;
+			if (nd->nd_bextpg == m->m_epg_npgs) {
+				printf("nfsm_set: build offs "
+				    "out of range\n");
+				nd->nd_bextpg--;
+				break;
+			}
+		}
+		nd->nd_bpos = (char *)(void *)
+		    PHYS_TO_DMAP(m->m_epg_pa[nd->nd_bextpg]);
+		if (nd->nd_bextpg == 0)
+			nd->nd_bpos += m->m_epg_1st_off;
+		if (offs > 0) {
+			nd->nd_bpos += offs;
+			nd->nd_bextpgsiz = rlen - offs;
+		} else if (nd->nd_bextpg == 0)
+			nd->nd_bextpgsiz = PAGE_SIZE - m->m_epg_1st_off;
+		else
+			nd->nd_bextpgsiz = PAGE_SIZE;
+	} else
+		nd->nd_bpos = mtod(m, char *) + offs;
 }