Wait for nbd-client before using /dev/nbd0

For explanation, see:

https://lists.freedesktop.org/archives/systemd-devel/2014-March/018053.html

But for the proper solution, see:

https://lists.freedesktop.org/archives/systemd-devel/2014-March/018054.html

Another option would just be to use a partitioned nbd device.  The nbd
device _partitions_ do not have this issue at all.

1 files changed, 14 insertions, 1 deletions

diff --git a/src/initrd/grok-block b/src/initrd/grok-block
index d3fe7a2..3ad0432 100755
--- a/src/initrd/grok-block
+++ b/src/initrd/grok-block
@@ -123,6 +123,14 @@ parent_device()
     printf '%s' "$d"
 }
 
+wait_for_files_()
+{
+    local f
+    for f in "$@"; do
+        while ! [ -e "$f" ]; do sleep 0.1; done
+    done
+}
+
 grok_block()
 {
   local mountpoint="/mnt/${DEVNAME##*/}"
@@ -140,7 +148,12 @@ grok_block()
   case "$DEVNAME" in
       # Avoid mouting this multiple times in case this script gets called multiple times,
       # because while it's mounted, the dmsetup stuff will fail with device busy.
-      /dev/nbd0) [ -e /bootwait/samizdat-nbd-dev ] && return ;;
+    /dev/nbd0)
+      if [ -e /bootwait/samizdat-nbd-dev ]
+        then return
+        else wait_for_files_ /sys/block/nbd0/pid
+      fi
+    ;;
   esac
   case "$ID_PART_ENTRY_NAME" in
       samizdat-grub-incomplete|samizdat-plaintext-incomplete|samizdat-luks-encrypted-incomplete) return ;;