Merge fix for BUG49628 to mysql-5.1-bugteam.

mysql-test/r/myisam.result

@@ -2313,4 +2313,17 @@ CHECK TABLE t1;
 Table	Op	Msg_type	Msg_text
 test.t1	check	status	OK
 DROP TABLE t1;
+#
+# BUG#49628 - corrupt table after legal SQL, LONGTEXT column
+#
+CREATE TABLE t1(a INT, b LONGTEXT, UNIQUE(a));
+REPLACE INTO t1 VALUES
+(1, REPEAT('a', 129015)),(1, NULL),
+(2, NULL),(3, NULL),(4, NULL),(5, NULL),(6, NULL),(7, NULL),
+(1, REPEAT('b', 129016)),(1, NULL),
+(1, REPEAT('c', 129015)),(1, REPEAT('d', 129015));
+CHECK TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	check	status	OK
+DROP TABLE t1;
 End of 5.1 tests

mysql-test/t/myisam.test

@@ -1563,5 +1563,18 @@ SET myisam_sort_buffer_size=@@global.myisam_sort_buffer_size;
 CHECK TABLE t1;
 DROP TABLE t1;
 
+
+--echo #
+--echo # BUG#49628 - corrupt table after legal SQL, LONGTEXT column
+--echo #
+CREATE TABLE t1(a INT, b LONGTEXT, UNIQUE(a));
+REPLACE INTO t1 VALUES
+(1, REPEAT('a', 129015)),(1, NULL),
+(2, NULL),(3, NULL),(4, NULL),(5, NULL),(6, NULL),(7, NULL),
+(1, REPEAT('b', 129016)),(1, NULL),
+(1, REPEAT('c', 129015)),(1, REPEAT('d', 129015));
+CHECK TABLE t1;
+DROP TABLE t1;
+
 --echo End of 5.1 tests
 

storage/myisam/mi_dynrec.c

@@ -933,8 +933,16 @@ static int update_dynamic_record(MI_INFO *info, my_off_t filepos, uchar *record,
   }
 
   if (block_info.next_filepos != HA_OFFSET_ERROR)
+  {
+    /*
+      delete_dynamic_record() may change data file position.
+      IO cache must be notified as it may still have cached
+      data, which has to be flushed later.
+    */
+    info->rec_cache.seek_not_done= 1;
     if (delete_dynamic_record(info,block_info.next_filepos,1))
       goto err;
+  }
   DBUG_RETURN(0);
 err:
   DBUG_RETURN(1);