Improve error msg on idmap mounts

Some filesystems don't support idmap mounts and just showing to the user invalid argument is not super clear. When errno is EINVAL, let's add a text hinting that the cause could be that idmap mounts are not supported on that filesystem used. Signed-off-by: Rodrigo Campos <[email protected]>
kinvolk · Dec 27, 2023 · 8ba9716 · 8ba9716
1 parent f987a57
commit 8ba9716
Showing 1 changed file with 8 additions and 1 deletion.
diff --git a/src/libcrun/linux.c b/src/libcrun/linux.c
@@ -4018,6 +4018,7 @@ maybe_get_idmapped_mount (runtime_spec_schema_config_schema *def, runtime_spec_s
   char proc_path[64];
   bool has_mappings;
   int ret;
+  char *extraMsg = "";
 
   *out_fd = -1;
 
@@ -4082,7 +4083,13 @@ maybe_get_idmapped_mount (runtime_spec_schema_config_schema *def, runtime_spec_s
 
   ret = syscall_mount_setattr (newfs_fd, "", AT_EMPTY_PATH | (recursive ? AT_RECURSIVE : 0), &attr);
   if (UNLIKELY (ret < 0))
-    return crun_make_error (err, errno, "mount_setattr `%s`", mnt->destination);
+    {
+      if (errno == EINVAL)
+        {
+          extraMsg = "(maybe the file system used doesn't support idmap mounts on this kernel?)";
+        }
+      return crun_make_error (err, errno, "mount_setattr `%s` %s", mnt->destination, extraMsg);
+    }
 
   *out_fd = get_and_reset (&newfs_fd);
   return 0;