Try to call udevadm settle in order to appease the race condition

build-inside-vm.sh

@@ -40,15 +40,6 @@ function cleanup() {
 }
 trap cleanup EXIT
 
-# Helper function: wait until a file path exists
-# ${1} - file path
-function wait_until_exists() {
-  until test -e "${1}"; do
-      echo "${1} doesn't exist yet..."
-      sleep 1
-  done
-}
-
 # Create the disk, partitions it, format the partition and mount the filesystem
 function setup_disk() {
   truncate -s "${DISK_SIZE}" "${IMAGE}"
@@ -59,8 +50,7 @@ function setup_disk() {
 
   LOOPDEV=$(losetup --find --partscan --show "${IMAGE}")
   # Partscan is racy
-  blockdev --rereadpt ${LOOPDEV}
-  wait_until_exists "${LOOPDEV}p2"
+  wait_until_settled "${LOOPDEV}"
   mkfs.btrfs "${LOOPDEV}p2"
   mount -o compress-force=zstd "${LOOPDEV}p2" "${MOUNT}"
 }
@@ -110,12 +100,22 @@ function image_cleanup() {
   fstrim --verbose "${MOUNT}"
 }
 
+# Helper function: wait until a given loop device has settled
+# ${1} - loop device
+function wait_until_settled() {
+  udevadm settle
+  blockdev --flushbufs --rereadpt ${1}
+  until test -e "${1}p2"; do
+      echo "${1}p2 doesn't exist yet..."
+      sleep 1
+  done
+}
+
 # Mount image helper (loop device + mount)
 function mount_image() {
   LOOPDEV=$(losetup --find --partscan --show "${1:-${IMAGE}}")
   # Partscan is racy
-  blockdev --rereadpt ${LOOPDEV}
-  wait_until_exists "${LOOPDEV}p2"
+  wait_until_settled ${LOOPDEV}
   mount -o compress-force=zstd "${LOOPDEV}p2" "${MOUNT}"
   # Setup bind mount to package cache
   mount --bind "/var/cache/pacman/pkg" "${MOUNT}/var/cache/pacman/pkg"