[dnbd3-rootfs] Add hard timeout to udevadm settle

For some reason (to be debugged by a bored person), sometimes
"udevadm settle" will hang in a way where it doesn't honor
the timeout given via "-t" -- handle this by using SIGKILL after
a couple more seconds.

1 files changed, 17 insertions, 3 deletions

diff --git a/modules.d/dnbd3-rootfs/hooks/s3-dnbd3root.sh b/modules.d/dnbd3-rootfs/hooks/s3-dnbd3root.sh
index e79938f6..802648d4 100755
--- a/modules.d/dnbd3-rootfs/hooks/s3-dnbd3root.sh
+++ b/modules.d/dnbd3-rootfs/hooks/s3-dnbd3root.sh
@@ -9,6 +9,20 @@ export LD_LIBRARY_PATH="/usr/local/lib"
 # hardcode dnbd device path
 declare -rg _dnbd3_dev="/dev/dnbd0"
 
+settle() {
+    if command -v timeout &> /dev/null; then
+        timeout -s 9 15 udevadm settle -t 10
+    else
+        local pid rem
+        udevadm settle -t 10 &
+        pid=$!
+        rem=15
+        while (( --rem > 0 )) && kill -0 "$pid"; do
+            sleep 1
+        done
+    fi >&2
+}
+
 # all outputs are redirected to stderr, since this functions should
 # only echo the path to the unpacked container to stdout.
 container_unpack_raw() {
@@ -18,7 +32,7 @@ container_unpack_raw() {
         echo "Failed to attach '$in_device' to '$out_device'."
         return 1
     fi >&2
-    udevadm settle >&2
+    settle
     echo "$out_device"
 }
 
@@ -34,7 +48,7 @@ container_unpack_xloop() {
         echo "Failed to attach '$in_device' to '$out_device'."
         return 1
     fi >&2
-    udevadm settle >&2
+    settle
     echo "$out_device"
 }
 # endregion
@@ -179,5 +193,5 @@ echo "Using read-only partition: $read_only_partition"
 # region add rw layer to dnbd3 image
 # don't be fooled to think we are done, the next part is crucial
 dmsetup-slx-device "$read_only_partition"
-udevadm settle
+settle
 # endregion