HBASE-11380 HRegion lock object is not being released properly, leading to snapshot failure

hbase-server/src/main/java/org/apache/hadoop/hbase/client/TableSnapshotScanner.java

@@ -176,15 +176,19 @@ public class TableSnapshotScanner extends AbstractClientScanner {
         }
       }
 
+      try {
         result = currentRegionScanner.next();
         if (result != null) {
           return result;
-      } else {
+        }
+      } finally {
+        if (result == null) {
           currentRegionScanner.close();
           currentRegionScanner = null;
         }        
       }
     }
+  }
 
   @Override
   public void close() {

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java

@@ -4841,8 +4841,12 @@ public class HRegion implements HeapSize { // , Writable{
     WALEdit walEdit = new WALEdit();
 
     // 1. Run pre-process hook
+    try {
       processor.preProcess(this, walEdit);
-
+    } catch (IOException e) {
+      closeRegionOperation();
+      throw e;
+    }
     // Short circuit the read only case
     if (processor.readOnly()) {
       try {