core: clone_device_node(): add debug message

For people who use debug messages, maybe it is helpful to know that
PrivateDevices= failed due to mknod(), and which device node.

(The other (un-logged) failures could be while mounting filesystems e.g. no
CAP_SYS_ADMIN which is the common case, or missing /dev/shm or /dev/pts,
or missing /dev/ptmx).

diff --git a/src/core/namespace.c b/src/core/namespace.c
index d6c1b1b2fc1f628f4dcaeec628ab8e2fd262ef3d..e1a9d7a92dcff6ca83be49d7003675bd4964303b 100644 (file)
--- a/src/core/namespace.c
+++ b/src/core/namespace.c
@@ -523,7 +523,7 @@ static int clone_device_node(const char *d, const char *temporary_mount) {
         mac_selinux_create_file_clear();
 
         if (r < 0)
-                return -errno;
+                return log_debug_errno(errno, "mknod failed for %s: %m", d);
 
         return 0;
 }