umount(8) will not unmount a filesystem if
	a) you supply the directory-name instead of the devicenode (or
	    host:directory-combination when using NFS) as an argument
	and b) the directory on which the filesystem is mounted (member
	    f_mntonname of the struct statfs) has a trailing slash

Fix: Apply this patch:



if ((mntsize = getmntinfo(&mntbuf, MNT_NOWAIT)) == 0) {
 		warn("getmntinfo");
+		free(longname);
 		return (NULL);
 	}
 	for (i = 0; i < mntsize; i++) {
 		if ((what == MNTON) && !strcmp(mntbuf[i].f_mntfromname, name)) {
 			if (type)
 				*type = mntbuf[i].f_type;
+			free(longname);
 			return (mntbuf[i].f_mntonname);
 		}
-		if ((what == MNTFROM) && !strcmp(mntbuf[i].f_mntonname, name)) {
+		if (((what == MNTFROM) && (!strcmp(mntbuf[i].f_mntonname, name))
+		    || (!strcmp(mntbuf[i].f_mntonname, longname)))) {
 			if (type)
 				*type = mntbuf[i].f_type;
+			free(longname);
 			return (mntbuf[i].f_mntfromname);
 		}
 	}
+	free(longname);
 	return (NULL);
 }


Alternatively mount_msdos, mount_cd9660 etc. need to be fixed to remove
trailing slashes.--7XjIAXa8be2EFYonGxMxJiZ1tPXUSy5gpsxcRYIRl3AQfgk3
Content-Type: text/plain; name="file.diff"
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Content-Disposition: attachment; filename="file.diff"

--- umount.c.sav	Thu Dec  4 08:36:22 1997
+++ umount.c	Sat Sep 11 05:29:27 1999
@@ -282,23 +282,34 @@
 {
 	struct statfs *mntbuf;
 	int i, mntsize;
+	char *longname;
+
+	if (NULL == (longname = malloc(strlen(name) + 2)))
+		err(1, NULL);
+	strcpy(longname, name);
+	strcat(longname, "/");
How-To-Repeat: 
	# mount_nfs remotehost:/remote/dir /local/dir/
	# mount -t nfs
	remotehost:/remote/dir on /local/dir/
	# umount /local/dir/
	umount: /local/dir: not currently mounted
	# umount /local/dir
	umount: /local/dir: not currently mounted
	# umount remotehost:/remote/dir
	# mount -t nfs
	#

	Note: You will need to call mount_nfs, mount_cd9660, mount_msdos etc.
	directly, as mount(8) catches this and removes the trailing slash.