bk commit into 5.0 tree (ingo:1.2147)

[ingo]

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5.0 repository of mydev. When mydev does a push these changes will
be propagated to the main repository and, within 24 hours after the
push, to the public repository.
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ChangeSet
  1.2147 06/04/11 19:05:02 ingo@stripped +1 -0
  Merge mysql.com:/home/mydev/mysql-4.1-bug18544
  into  mysql.com:/home/mydev/mysql-5.0-bug18544

  sql/lock.cc
    1.87 06/04/11 19:04:54 ingo@stripped +2 -2
    Bug#18544 - LOCK TABLES timeout causes MyISAM table corruption
    Manual merge from 4.1.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	ingo
# Host:	chilla.local
# Root:	/home/mydev/mysql-5.0-bug18544/RESYNC

--- 1.86/sql/lock.cc	2006-04-05 14:39:15 +02:00
+++ 1.87/sql/lock.cc	2006-04-11 19:04:54 +02:00
@@ -78,6 +78,7 @@
 
 static MYSQL_LOCK *get_lock_data(THD *thd, TABLE **table,uint count,
 				 uint flags, TABLE **write_locked);
+static void reset_lock_data(MYSQL_LOCK *sql_lock);
 static int lock_external(THD *thd, TABLE **table,uint count);
 static int unlock_external(THD *thd, TABLE **table,uint count);
 static void print_lock_error(int error, const char *);
@@ -135,10 +136,12 @@
       */
       if (wait_if_global_read_lock(thd, 1, 1))
       {
+        /* Clear the lock type of all lock data to avoid reusage. */
+        reset_lock_data(sql_lock);
 	my_free((gptr) sql_lock,MYF(0));
 	sql_lock=0;
 	break;
-      }	
+      }
       if (thd->version != refresh_version)
       {
 	my_free((gptr) sql_lock,MYF(0));
@@ -149,6 +152,8 @@
     thd->proc_info="System lock";
     if (lock_external(thd, tables, count))
     {
+      /* Clear the lock type of all lock data to avoid reusage. */
+      reset_lock_data(sql_lock);
       my_free((gptr) sql_lock,MYF(0));
       sql_lock=0;
       break;
@@ -193,6 +198,8 @@
     mysql_unlock_tables(thd,sql_lock);
     thd->locked=0;
 retry:
+    /* Clear the lock type of all lock data to avoid reusage. */
+    reset_lock_data(sql_lock);
     sql_lock=0;
     if (flags & MYSQL_LOCK_NOTIFY_IF_NEED_REOPEN)
     {
@@ -700,6 +707,9 @@
       if (table->db_stat & HA_READ_ONLY)
       {
 	my_error(ER_OPEN_AS_READONLY, MYF(0), table->alias);
+        /* Clear the lock type of the lock data that are stored already. */
+        sql_lock->lock_count= locks - sql_lock->locks;
+        reset_lock_data(sql_lock);
 	my_free((gptr) sql_lock,MYF(0));
 	DBUG_RETURN(0);
       }
@@ -721,6 +731,48 @@
 	(*org_locks)->debug_print_param= (void *) table;
   }
   DBUG_RETURN(sql_lock);
+}
+
+
+/*
+  Reset lock type in lock data.
+
+  SYNOPSIS
+    reset_lock_data()
+      sql_lock                  The MySQL lock.
+
+  DESCRIPTION
+
+    After a locking error we want to quit the locking of the table(s).
+    The test case in the bug report for Bug #18544 has the following
+    cases: 1. Locking error in lock_external() due to InnoDB timeout.
+    2. Locking error in get_lock_data() due to missing write permission.
+    3. Locking error in wait_if_global_read_lock() due to lock conflict.
+
+    In all these cases we have already set the lock type into the lock
+    data of the open table(s). If the table(s) are in the open table
+    cache, they could be reused with the non-zero lock type set. This
+    could lead to ignoring a different lock type with the next lock.
+
+    Clear the lock type of all lock data. This ensures that the next
+    lock request will set its lock type properly.
+
+  RETURN
+    void
+*/
+
+static void reset_lock_data(MYSQL_LOCK *sql_lock)
+{
+  THR_LOCK_DATA **ldata;
+  THR_LOCK_DATA **ldata_end;
+
+  for (ldata= sql_lock->locks, ldata_end= ldata + sql_lock->lock_count;
+       ldata < ldata_end;
+       ldata++)
+  {
+    /* Reset lock type. */
+    (*ldata)->type= TL_UNLOCK;
+  }
 }