From 86b9c733ad0a571390acb42f7bec1305b78a8ada Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Mon, 13 Jun 1994 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1994-06-13

---
 carrera/l.s    |  8 ++++----
 port/devproc.c | 12 ++++++------
 port/pgrp.c    | 53 +++++++++++++++++++++++++++++++++++++++++++-------
 port/portdat.h |  2 ++
 4 files changed, 58 insertions(+), 17 deletions(-)

diff --git a/carrera/l.s b/carrera/l.s
index 35a02288a6479ac2758ef3e9d938dd5b2c08f576..fb55f251a143a01f787400edfb1940bd68036605 100644
--- a/carrera/l.s
+++ b/carrera/l.s
@@ -403,6 +403,10 @@ sysrestore:
 	MOVW	R26, M(EPC)
 	ERET
 
+TEXT	forkret(SB), $0
+	MOVW	R0, R1			/* Fake out system call return */
+	JMP	sysrestore
+
 notsys:
 	JAL	trap(SB)
 restore:
@@ -432,10 +436,6 @@ waskernel:
 	MOVW	R26, M(EPC)
 	ERET
 
-TEXT	forkret(SB), $0
-	MOVW	R0, R1			/* Fake out system call return */
-	JMP	sysrestore
-
 TEXT	saveregs(SB), $-4
 	MOVV	R1, Ureg_r1(SP)
 	MOVV	R2, Ureg_r2(SP)
diff --git a/port/devproc.c b/port/devproc.c
index ac44726a08859487d40a4c4222f9f20d4cc9694e..ab5855016514f4d493b856bbcf5023ae59ad8839 100644
--- a/port/devproc.c
+++ b/port/devproc.c
@@ -483,22 +483,22 @@ mntscan(Mntwalk *mw)
 {
 	Pgrp *pg;
 	Mount *t;
-	int nxt;
+	Mhead *f;
+	int nxt, i;
 	ulong last, bestmid;
-	Mhead **h, **he, *f;
 
 	pg = up->pgrp;
 	rlock(&pg->ns);
 
 	nxt = 0;
-	last = 0;
 	bestmid = ~0;
+
+	last = 0;
 	if(mw->mh)
 		last = mw->cm->mountid;
 
-	he = &pg->mnthash[MNTHASH];
-	for(h = pg->mnthash; h < he; h++) {
-		for(f = *h; f; f = f->hash) {
+	for(i = 0; i < MNTHASH; i++) {
+		for(f = pg->mnthash[i]; f; f = f->hash) {
 			for(t = f->mount; t; t = t->next) {
 				if(mw->mh == 0 ||
 				  (t->mountid > last && t->mountid < bestmid)) {
diff --git a/port/pgrp.c b/port/pgrp.c
index a4a518507550b72880e6aabe033613880927b9c1..ffa922401f472118d1b344f4e2b20b6d5a442bce 100644
--- a/port/pgrp.c
+++ b/port/pgrp.c
@@ -73,19 +73,43 @@ closepgrp(Pgrp *p)
 	}
 }
 
+void
+pgrpinsert(Mount **order, Mount *m)
+{
+	Mount *f;
+
+	m->order = 0;
+	if(*order == 0) {
+		*order = m;
+		return;
+	}
+	for(f = *order; f; f = f->order) {
+		if(m->mountid < f->mountid) {
+			m->order = f;
+			*order = m;
+			return;
+		}
+		order = &f->order;
+	}
+	*order = m;
+}
+
+/*
+ * pgrpcpy MUST preserve the mountid allocation order of the parent group
+ */
 void
 pgrpcpy(Pgrp *to, Pgrp *from)
 {
-	Mhead **h, **e, *f, **tom, **l, *mh;
-	Mount *n, *m, **link;
+	int i;
+	Mount *n, *m, **link, *order;
+	Mhead *f, **tom, **l, *mh;
 
 	rlock(&from->ns);
-
-	e = &from->mnthash[MNTHASH];
+	order = 0;
 	tom = to->mnthash;
-	for(h = from->mnthash; h < e; h++) {
+	for(i = 0; i < MNTHASH; i++) {
 		l = tom++;
-		for(f = *h; f; f = f->hash) {
+		for(f = from->mnthash[i]; f; f = f->hash) {
 			mh = smalloc(sizeof(Mhead));
 			mh->from = f->from;
 			incref(mh->from);
@@ -93,12 +117,27 @@ pgrpcpy(Pgrp *to, Pgrp *from)
 			l = &mh->hash;
 			link = &mh->mount;
 			for(m = f->mount; m; m = m->next) {
-				n = newmount(mh, m->to, m->flag, m->spec);
+				n = smalloc(sizeof(Mount));
+				n->to = m->to;
+				incref(n->to);
+				n->head = mh;
+				n->flag = m->flag;
+				if(m->spec != 0)
+					strcpy(n->spec, m->spec);
+				m->copy = n;
+				pgrpinsert(&order, m);
 				*link = n;
 				link = &n->next;	
 			}
 		}
 	}
+	/*
+	 * Allocate mount ids in the same sequence as the parent group
+	 */
+	lock(&mountid);
+	for(m = order; m; m = m->order)
+		m->copy->mountid = mountid.ref++;
+	unlock(&mountid);
 	runlock(&from->ns);
 }
 
diff --git a/port/portdat.h b/port/portdat.h
index b723f863c4dd30a10dba8161507d814e39b5ce6c..cc1e9529758f5a54f1c4f22ee459224908a6c564 100644
--- a/port/portdat.h
+++ b/port/portdat.h
@@ -216,6 +216,8 @@ struct Mount
 	ulong	mountid;
 	Mount*	next;
 	Mhead*	head;
+	Mount*	copy;
+	Mount*	order;
 	Chan*	to;			/* channel replacing channel */
 	int	flag;
 	char	spec[NAMELEN];