Don't let fuse enter in background because we loose our workers.

Instead, use Sys_Daemon and enter in background ourselves so that
we create the worker pool while in background

tools/fuse/akt-commands-mount.adb

@@ -15,10 +15,17 @@
 --  See the License for the specific language governing permissions and
 --  limitations under the License.
 -----------------------------------------------------------------------
+with System;
 with Fuse;
 with AKT.Filesystem;
 package body AKT.Commands.Mount is
 
+   use type System.Address;
+
+   function Sys_Daemon (No_Chdir : in Integer; No_Close : in Integer) return Integer
+     with Import => True, Convention => C, Link_Name => "daemon";
+   pragma Weak_External (Sys_Daemon);
+
    Mount_Command          : aliased Command_Type;
 
    --  ------------------------------
@@ -37,11 +44,35 @@ package body AKT.Commands.Mount is
       Data.Wallet := Context.Wallet'Unchecked_Access;
       Data.Direct_IO := not Command.Enable_Cache;
 
-      Context.Open_Keystore (Args, Use_Worker => True);
+      --  We can open the keystore before going in background
+      --  but don't create the worker tasks.
+      Context.Open_Keystore (Args, Use_Worker => False);
+
+      --  If daemon(3) is available and -d is defined, run it so that the parent
+      --  process terminates and the child process continues.
+      if not Command.Foreground and Sys_Daemon'Address /= System.Null_Address then
+         declare
+            Result : constant Integer := Sys_Daemon (1, 0);
+         begin
+            if Result /= 0 then
+               AKT.Commands.Log.Error ("Cannot run in background");
+            end if;
+         end;
+      end if;
 
-      if Command.Foreground then
-         Mount_Arguments.Append ("-f");
+      --  Now we can start the workers.
+      if Context.Worker_Count > 1 then
+         Context.Workers := new Keystore.Task_Manager (Context.Worker_Count);
+         Keystore.Start (Context.Workers);
+         Context.Wallet.Set_Work_Manager (Context.Workers);
       end if;
+
+      --  Always run in foreground because Open_Keystore has started some tasks
+      --  and we need them (they will dead in the child if fuse runs as daemon).
+      Mount_Arguments.Append ("-f");
+
+      --  Even if the Keystore is thread-safe, run only one thread in fuse.
+      Mount_Arguments.Append ("-s");
       if Command.Verbose_Fuse then
          Mount_Arguments.Append ("-d");
       end if;
@@ -67,7 +98,7 @@ package body AKT.Commands.Mount is
                         Long_Switch => "--foreground",
                         Help => -("Run as foreground (no daemonize)"));
       GC.Define_Switch (Config => Config,
-                        Output => Command.Foreground'Access,
+                        Output => Command.Verbose_Fuse'Access,
                         Long_Switch => "--debug-fuse",
                         Help => -("Enable debug output of fuse library"));
       GC.Define_Switch (Config => Config,