autofs-5.1.8 - fix incorrect path for is_mounted() in try_remount()

From: Ian Kent <raven@themaw.net>

A regression was introduced when the offset mount handling was rewritten.

It resulted in an incorrect path sometimes being used in an is_mounted()
check.

Signed-off-by: Ian Kent <raven@themaw.net>
---
 CHANGELOG    |    1 +
 lib/mounts.c |   26 +++++++++++++++++++++-----
 2 files changed, 22 insertions(+), 5 deletions(-)

--- autofs-5.1.7.orig/CHANGELOG
+++ autofs-5.1.7/CHANGELOG
@@ -111,6 +111,7 @@
 - fix deadlock with hosts map reload.
 - fix memory leak in update_hosts_mounts().
 - fix minus only option handling in concat_options().
+- fix incorrect path for is_mounted() in try_remount().
 
 25/01/2021 autofs-5.1.7
 - make bind mounts propagation slave by default.
--- autofs-5.1.7.orig/lib/mounts.c
+++ autofs-5.1.7/lib/mounts.c
@@ -2803,14 +2803,30 @@ int try_remount(struct autofs_point *ap,
 			ap->flags &= ~MOUNT_FLAG_DIR_CREATED;
 		else
 			ap->flags |= MOUNT_FLAG_DIR_CREATED;
+		goto done;
+	}
+
+	me->flags &= ~MOUNT_FLAG_DIR_CREATED;
+	/* Direct or offset mount, key is full path */
+	if (MM_PARENT(me)->key[0] == '/') {
+		if (!is_mounted(MM_PARENT(me)->key, MNTS_REAL))
+			me->flags |= MOUNT_FLAG_DIR_CREATED;
 	} else {
-		me->flags &= ~MOUNT_FLAG_DIR_CREATED;
-		if (type == t_offset) {
-			if (!is_mounted(MM_PARENT(me)->key, MNTS_REAL))
-				me->flags |= MOUNT_FLAG_DIR_CREATED;
+		char *p_key = MM_PARENT(me)->key;
+		char mp[PATH_MAX + 1];
+		int len;
+
+		len = mount_fullpath(mp, PATH_MAX, ap->path, ap->len, p_key);
+		if (len > PATH_MAX) {
+			/* This should never happen due to earlier checks */
+			error(ap->logopt, "mountpoint path too long");
+			return 0;
 		}
-	}
 
+		if (!is_mounted(mp, MNTS_REAL))
+			me->flags |= MOUNT_FLAG_DIR_CREATED;
+	}
+done:
 	/*
 	 * Either we opened the mount or we're re-reading the map.
 	 * If we opened the mount and ioctlfd is not -1 we have