dracut modules: wait for disks to show up

dracut-modules/90void-usb/squashfs-img.sh

@@ -17,7 +17,40 @@ case "$CONTAINER" in
     emergency_shell
 esac
 
-mount -t f2fs -o nodev,nosuid "$CONTAINER" /sysroot/container
+# try to wait for $CONTAINER to be available
+function mount_container {
+  mount -t f2fs -o nodev,nosuid "$CONTAINER" /sysroot/container;
+}
+
+if [ -b "$CONTAINER" ]; then
+  mount_container
+else
+  sleep 1
+  if [ -b "$CONTAINER" ]; then
+    mount_container
+  else
+    sleep 1
+    if [ -b "$CONTAINER" ]; then
+      mount_container
+    else
+      sleep 3
+      if [ -b "$CONTAINER" ]; then
+        mount_container
+      else
+        sleep 5
+        if [ -b "$CONTAINER" ]; then
+          mount_container
+        else
+          sleep 10
+          if [ -b "$CONTAINER" ]; then
+            mount_container
+          fi
+          # assume that the drive won't show up after more than 20s
+        fi
+      fi
+    fi
+  fi
+fi
 
 if [ -f /sysroot/container/squashfs.img ]; then
   losetup -r -f /sysroot/container/squashfs.img