nixos-modules/host: add option microvm.virtiofsd.inodeFileHandles

Author: astro

nixos-modules/host/default.nix

@@ -283,6 +283,9 @@ in
               --rlimit-nofile ${toString serviceConfig.LimitNOFILE} \
               --thread-pool-size `nproc` \
               --posix-acl --xattr \
+              ${lib.optionalString (config.microvm.virtiofsd.inodeFileHandles != null)
+                "--inode-file-handles=${config.microvm.virtiofsd.inodeFileHandles}"
+              } \
               &
             # detach from shell, but remain in systemd cgroup
             disown

nixos-modules/host/options.nix

@@ -137,5 +137,20 @@
         This includes declarative `config.microvm.vms` as well as MicroVMs that are managed through the `microvm` command.
       '';
     };
+
+    virtiofsd.inodeFileHandles = mkOption {
+      type = with types; nullOr (enum [
+        "never" "prefer" "mandatory"
+      ]);
+      default = null;
+      description = ''
+        When to use file handles to reference inodes instead of O_PATH file descriptors
+        (never, prefer, mandatory)
+
+        Allows you to overwrite default behavior in case you hit "too
+        many open files" on eg. ZFS.
+        <https://gitlab.com/virtio-fs/virtiofsd/-/issues/121>
+      '';
+    };
   };
 }