Fix for bug #35392: Delete all statement does not execute properly

after few delete statements

Problem: changing a file size might require that it must be 
unmapped beforehand.
  
Fix: unmap the file before changing its size.


mysql-test/r/temp_table.result:
  Fix for bug #35392: Delete all statement does not execute properly 
  after few delete statements
    - test result.
mysql-test/t/temp_table.test:
  Fix for bug #35392: Delete all statement does not execute properly 
  after few delete statements
    - test case.
storage/myisam/mi_delete_all.c:
  Fix for bug #35392: Delete all statement does not execute properly 
  after few delete statements
    - unmap file before changing its size as it's required 
      by SetEndOfFile() function (see my_chsize()).
    - as no other threads allowed to perform concurrent inserts 
      when delete_all is called, mmap_lock locking removed.

1 files changed, 11 insertions, 0 deletions

diff --git a/mysql-test/r/temp_table.result b/mysql-test/r/temp_table.result
index 1c846700346..6df09463d02 100644
--- a/mysql-test/r/temp_table.result
+++ b/mysql-test/r/temp_table.result
@@ -184,3 +184,14 @@ select * from t1;
 a
 42
 drop table t1;
+CREATE TEMPORARY TABLE t1(a INT, b VARCHAR(20));
+INSERT INTO t1 VALUES(1, 'val1'), (2, 'val2'), (3, 'val3');
+DELETE FROM t1 WHERE a=1;
+SELECT count(*) FROM t1;
+count(*)
+2
+DELETE FROM t1;
+SELECT * FROM t1;
+a	b
+DROP TABLE t1;
+End of 5.1 tests