Get rid of the 'mount read: i/o on hungup channel' 
errors when unmounting some common file servers

tapefs now without wstat() patch.

-Steve

Reference: /n/sources/patch/applied/grumble-on-dismount2
Date: Mon Feb 28 16:17:19 CET 2005

--- /sys/src/cmd/ramfs.c	Mon Feb 28 16:14:39 2005
+++ /sys/src/cmd/ramfs.c	Mon Feb 28 16:14:33 2005
@@ -745,7 +745,7 @@
 void
 io(void)
 {
-	char *err, buf[20];
+	char *err, buf[40];
 	int n, pid, ctl;
 
 	pid = getpid();
@@ -771,6 +771,12 @@
 		 * so we wait for the error.
 		 */
 		n = read9pmsg(mfd[0], mdata, messagesize);
+		if(n < 0){
+			errstr(buf, sizeof buf);
+			if (buf[0]=='\0' || strncmp(buf, "i/o on hungup channel", 22)==0)
+				exits("");
+			error("mount read");
+		}
 		if(n < 0)
 			error("mount read");
 		if(n == 0)
--- /sys/src/cmd/ip/ftpfs/ftpfs.c	Mon Feb 28 16:15:00 2005
+++ /sys/src/cmd/ip/ftpfs/ftpfs.c	Mon Feb 28 16:14:57 2005
@@ -247,15 +247,19 @@
 void
 io(void)
 {
-	char *err;
+	char *err, buf[ERRMAX];
 	int n;
 
 	kapid = kaproc();
 
 	while(!dying){
 		n = read9pmsg(mfd, mdata, messagesize);
-		if(n <= 0)
-			fatal("mount read");
+		if(n <= 0){
+			errstr(buf, sizeof buf);
+			if (buf[0]=='\0' || strncmp(buf, "i/o on hungup channel", 22)==0)
+				exits("");
+			fatal("mount read: %s\n", buf);
+		}
 		if(convM2S(mdata, n, &thdr) == 0)
 			continue;
 
--- /sys/src/cmd/tapefs/fs.c	Mon Feb 28 16:15:19 2005
+++ /sys/src/cmd/tapefs/fs.c	Mon Feb 28 16:15:16 2005
@@ -541,7 +541,7 @@
 		if(write(mfd[1], mdata, n) != n)
 			error("mount write");
 	}
-	if (buf[0]=='\0' || strncmp(buf, "write to hung", 13)==0)
+	if (buf[0]=='\0' || strncmp(buf, "i/o on hungup channel", 22)==0)
 		exits("");
 	fprint(2, "%s: mount read: %s\n", argv0, buf);
 	exits(buf);