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

@@ -176,12 +176,16 @@ public class TableSnapshotScanner extends AbstractClientScanner {
         }
       }
 
-      result = currentRegionScanner.next();
-      if (result != null) {
-        return result;
-      } else {
-        currentRegionScanner.close();
-        currentRegionScanner = null;
+      try {
+        result = currentRegionScanner.next();
+        if (result != null) {
+          return result;
+        }
+      } finally {
+        if (result == null) {
+          currentRegionScanner.close();
+          currentRegionScanner = null;
+        }        
       }
     }
   }

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
-    processor.preProcess(this, walEdit);
-
+    try {
+      processor.preProcess(this, walEdit);
+    } catch (IOException e) {
+      closeRegionOperation();
+      throw e;
+    }
     // Short circuit the read only case
     if (processor.readOnly()) {
       try {