From 995bfb15bd0a26b95cb56dc4dc60a8bf33c60141 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Sun, 8 Aug 1993 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1993-08-08

---
 port/devmnt.c | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/port/devmnt.c b/port/devmnt.c
index dc3c9c084286bd2711c2450f44ccf583d953698f..1ac57e8880f548ce6380526548f2552697a0656b 100644
--- a/port/devmnt.c
+++ b/port/devmnt.c
@@ -79,6 +79,7 @@ Chan*
 mntattach(char *muxattach)
 {
 	Mnt *m;
+	int nest;
 	Chan *c, *mc;
 	char buf[NAMELEN];
 	struct bogus{
@@ -164,6 +165,28 @@ mntattach(char *muxattach)
 	mattach(m, c, bogus.spec);
 	poperror();
 
+	/* Work out how deep we are nested and reduce the blocksize
+	 * accordingly
+	 */
+	nest = 0;
+	mc = m->c;
+	while(mc) {
+		if(mc->type != devno('M', 0))
+			break;
+		nest++;
+		if(mc->mntptr == 0)
+			break;
+		mc = mc->mntptr->c;
+	}
+	m->blocksize -= nest * 32;
+
+	/*
+	 * Detect a recursive mount for a mount point served by exportfs.
+	 * If CHDIR is clear in the returned qid the foreign server is
+	 * requesting the mount point be folded into the connection
+	 * to the exportfs. In this case the remote mount driver does
+	 * the multiplexing.
+	 */
 	mc = m->c;
 	if(mc->type == devno('M', 0) && (c->qid.path&CHDIR) == 0) {
 		mclose(m, c);
@@ -280,12 +303,14 @@ mntwalk(Chan *c, char *name)
 	c->qid = r->reply.qid;
 	op = c->path;
 	c->path = ptenter(&m->tree, op, name);
-/* ASSERT */
+
+/* ASSERT do not remove */
 if(op->ref == 0) {
 	char buf[128];
 	ptpath(op, buf, sizeof(buf));
 	print("PATH: '%s' walking %s\n", op, name);
 }
+
 	decref(op);
 
 	poperror();