Wait for LUKS configfs API to be ready

Partially resolves: #109

On Fedora 42, LUKS-encrypted volumes fail to be unlocked in the crash
kernel because somehow the volume keys are yet to be available. Wait for
the API to be ready before triggering restoring volume keys so that
later the keys will be available for cryptsetup to unlock the volumes.

Fixes: d9677e1 ("Support dumping to a LUKS-encrypted target")

Signed-off-by: Coiby Xu <[email protected]>

Author: coiby

dracut/99kdumpbase/kexec-crypt-setup.sh

@@ -1,3 +1,21 @@
 #!/bin/sh
 #
-echo true > /sys/kernel/config/crash_dm_crypt_keys/restore
+LUKS_CONFIGFS_RESTORE=/sys/kernel/config/crash_dm_crypt_keys/restore
+RESTORED=1
+MAX_WAIT_TIME=10
+wait_time=0
+
+while [ $wait_time -lt $MAX_WAIT_TIME ]; do
+    [ -e $LUKS_CONFIGFS_RESTORE ] && break
+    sleep 1
+    wait_time=$((wait_time + 1))
+done
+
+if [ $wait_time -ge $MAX_WAIT_TIME ]; then
+    echo "$LUKS_CONFIGFS_RESTORE isn't ready after ${MAX_WAIT_TIME}s, something wrong!"
+    exit 1
+fi
+
+if ! grep -q "$RESTORED" "$LUKS_CONFIGFS_RESTORE"; then
+    echo $RESTORED > $LUKS_CONFIGFS_RESTORE
+fi