refactor: use shell timeout command for flush operation

Co-Authored-By: maru@blacksmith.sh <adityamaru@gmail.com>

Author: devin-ai-integration[bot]

dist/index.js

@@ -56,6 +56,9 @@ async function getDeviceFromMount(mountPath: string): Promise<string | null> {
   return null;
 }
 
+const FLUSH_TIMEOUT_SECS = 10;
+const TIMEOUT_EXIT_CODE = 124;
+
 async function flushBlockDevice(devicePath: string): Promise<void> {
   const deviceName = devicePath.replace("/dev/", "");
   if (!deviceName) {
@@ -75,11 +78,29 @@ async function flushBlockDevice(devicePath: string): Promise<void> {
 
   const startTime = Date.now();
   try {
-    await execAsync(`sudo blockdev --flushbufs ${devicePath}`, {
-      timeout: 10000,
-    });
+    const { stdout, stderr } = await execAsync(
+      `timeout ${FLUSH_TIMEOUT_SECS} sudo blockdev --flushbufs ${devicePath}; echo "EXIT_CODE:$?"`,
+    );
     const duration = Date.now() - startTime;
 
+    // Parse exit code from output
+    const exitCodeMatch = stdout.match(/EXIT_CODE:(\d+)/);
+    const exitCode = exitCodeMatch ? parseInt(exitCodeMatch[1], 10) : 0;
+
+    if (exitCode === TIMEOUT_EXIT_CODE) {
+      core.info(
+        `guest flush timed out for ${devicePath} after ${FLUSH_TIMEOUT_SECS}s`,
+      );
+      return;
+    }
+
+    if (exitCode !== 0) {
+      core.info(
+        `guest flush failed for ${devicePath} after ${duration}ms: exit code ${exitCode}, stderr: ${stderr}`,
+      );
+      return;
+    }
+
     let afterStats = "";
     try {
       const { stdout } = await execAsync(`cat ${statPath}`);