zil_suspend: fix cookie leak if ZIL crashes during wait

Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <alexander.motin@TrueNAS.com>
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Closes openzfs#17622

Author: robn

module/zfs/zil.c

@@ -4485,16 +4485,16 @@ zil_suspend(const char *osname, void **cookiep)
 			cv_wait(&zilog->zl_cv_suspend, &zilog->zl_lock);
 		mutex_exit(&zilog->zl_lock);
 
-		if (cookiep == NULL)
+		if (zilog->zl_restart_txg > 0) {
+			/* ZIL crashed while we were waiting. */
+			zil_resume(os);
+			error = SET_ERROR(EBUSY);
+		} else if (cookiep == NULL)
 			zil_resume(os);
 		else
 			*cookiep = os;
 
-		if (zilog->zl_restart_txg > 0)
-			/* ZIL crashed while we were waiting. */
-			return (SET_ERROR(EBUSY));
-
-		return (0);
+		return (error);
 	}
 
 	/*