Add support for ext_pgs mbufs to nfsm_strtom().

Also, add a new function nfsm_add_ext_pgs() which will either add a page
or add a new ext_pgs mbuf with a page to the mbuf list. Used by nfsm_strtom().
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.

2 files changed, 73 insertions, 12 deletions

diff --git a/sys/fs/nfs/nfs_commonsubs.c b/sys/fs/nfs/nfs_commonsubs.c
index b810096e73a9..9da9f7f5bbdc 100644
--- a/sys/fs/nfs/nfs_commonsubs.c
+++ b/sys/fs/nfs/nfs_commonsubs.c
@@ -832,22 +832,38 @@ nfsm_strtom(struct nfsrv_descript *nd, const char *cp, int siz)
 	bytesize = NFSX_UNSIGNED + siz + rem;
 	m2 = nd->nd_mb;
 	cp2 = nd->nd_bpos;
-	left = M_TRAILINGSPACE(m2);
+	if ((nd->nd_flag & ND_EXTPG) != 0)
+		left = nd->nd_bextpgsiz;
+	else
+		left = M_TRAILINGSPACE(m2);
 
+	KASSERT(((m2->m_flags & (M_EXT | M_EXTPG)) ==
+	    (M_EXT | M_EXTPG) && (nd->nd_flag & ND_EXTPG) != 0) ||
+	    ((m2->m_flags & (M_EXT | M_EXTPG)) !=
+	    (M_EXT | M_EXTPG) && (nd->nd_flag & ND_EXTPG) == 0),
+	    ("nfsm_strtom: ext_pgs and non-ext_pgs mbufs mixed"));
 	/*
 	 * Loop around copying the string to mbuf(s).
 	 */
 	while (siz > 0) {
 		if (left == 0) {
-			if (siz > ncl_mbuf_mlen)
-				NFSMCLGET(m1, M_WAITOK);
-			else
-				NFSMGET(m1);
-			m1->m_len = 0;
-			m2->m_next = m1;
-			m2 = m1;
-			cp2 = mtod(m2, caddr_t);
-			left = M_TRAILINGSPACE(m2);
+			if ((nd->nd_flag & ND_EXTPG) != 0) {
+				m2 = nfsm_add_ext_pgs(m2,
+				    nd->nd_maxextsiz, &nd->nd_bextpg);
+				cp2 = (char *)(void *)PHYS_TO_DMAP(
+				    m2->m_epg_pa[nd->nd_bextpg]);
+				nd->nd_bextpgsiz = left = PAGE_SIZE;
+			} else {
+				if (siz > ncl_mbuf_mlen)
+					NFSMCLGET(m1, M_WAITOK);
+				else
+					NFSMGET(m1);
+				m1->m_len = 0;
+				cp2 = mtod(m1, char *);
+				left = M_TRAILINGSPACE(m1);
+				m2->m_next = m1;
+				m2 = m1;
+			}
 		}
 		if (left >= siz)
 			xfer = siz;
@@ -855,18 +871,31 @@ nfsm_strtom(struct nfsrv_descript *nd, const char *cp, int siz)
 			xfer = left;
 		NFSBCOPY(cp, cp2, xfer);
 		cp += xfer;
+		cp2 += xfer;
 		m2->m_len += xfer;
 		siz -= xfer;
 		left -= xfer;
+		if ((nd->nd_flag & ND_EXTPG) != 0) {
+			nd->nd_bextpgsiz -= xfer;
+			m2->m_epg_last_len += xfer;
+		}
 		if (siz == 0 && rem) {
 			if (left < rem)
 				panic("nfsm_strtom");
-			NFSBZERO(cp2 + xfer, rem);
+			NFSBZERO(cp2, rem);
 			m2->m_len += rem;
+			cp2 += rem;
+			if ((nd->nd_flag & ND_EXTPG) != 0) {
+				nd->nd_bextpgsiz -= rem;
+				m2->m_epg_last_len += rem;
+			}
 		}
 	}
 	nd->nd_mb = m2;
-	nd->nd_bpos = mtod(m2, caddr_t) + m2->m_len;
+	if ((nd->nd_flag & ND_EXTPG) != 0)
+		nd->nd_bpos = cp2;
+	else
+		nd->nd_bpos = mtod(m2, char *) + m2->m_len;
 	return (bytesize);
 }
 
@@ -4845,3 +4874,34 @@ nfsm_set(struct nfsrv_descript *nd, u_int offs)
 	} else
 		nd->nd_bpos = mtod(m, char *) + offs;
 }
+
+/*
+ * Grow a ext_pgs mbuf list.  Either allocate another page or add
+ * an mbuf to the list.
+ */
+struct mbuf *
+nfsm_add_ext_pgs(struct mbuf *m, int maxextsiz, int *bextpg)
+{
+	struct mbuf *mp;
+	vm_page_t pg;
+
+	if ((m->m_epg_npgs + 1) * PAGE_SIZE > maxextsiz) {
+		mp = mb_alloc_ext_plus_pages(PAGE_SIZE, M_WAITOK);
+		*bextpg = 0;
+		m->m_next = mp;
+	} else {
+		do {
+			pg = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL |
+			    VM_ALLOC_NOOBJ | VM_ALLOC_NODUMP |
+			    VM_ALLOC_WIRED);
+			if (pg == NULL)
+				vm_wait(NULL);
+		} while (pg == NULL);
+		m->m_epg_pa[m->m_epg_npgs] = VM_PAGE_TO_PHYS(pg);
+		*bextpg = m->m_epg_npgs;
+		m->m_epg_npgs++;
+		m->m_epg_last_len = 0;
+		mp = m;
+	}
+	return (mp);
+}
diff --git a/sys/fs/nfs/nfs_var.h b/sys/fs/nfs/nfs_var.h
index 5efa054af82c..e92a6859d0de 100644
--- a/sys/fs/nfs/nfs_var.h
+++ b/sys/fs/nfs/nfs_var.h
@@ -361,6 +361,7 @@ void nfsv4_freeslot(struct nfsclsession *, int);
 struct ucred *nfsrv_getgrpscred(struct ucred *);
 struct nfsdevice *nfsv4_findmirror(struct nfsmount *);
 void nfsm_set(struct nfsrv_descript *, u_int);
+struct mbuf *nfsm_add_ext_pgs(struct mbuf *, int, int *);
 
 /* nfs_clcomsubs.c */
 void nfsm_uiombuf(struct nfsrv_descript *, struct uio *, int);