1 files changed, 59 insertions, 0 deletions
diff --git a/storage/innobase/buf/buf0block_hint.cc b/storage/innobase/buf/buf0block_hint.cc
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index 00000000000..6d99d0b61f0
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+++ b/storage/innobase/buf/buf0block_hint.cc
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+/*****************************************************************************
+
+Copyright (c) 2020, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 2020, MariaDB Corporation.
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License, version 2.0, as published by the
+Free Software Foundation.
+
+This program is also distributed with certain software (including but not
+limited to OpenSSL) that is licensed under separate terms, as designated in a
+particular file or component or in included license documentation. The authors
+of MySQL hereby grant you an additional permission to link the program and
+your derivative works with the separately licensed software that they have
+included with MySQL.
+
+This program is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+FOR A PARTICULAR PURPOSE. See the GNU General Public License, version 2.0,
+for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
+
+*****************************************************************************/
+
+#include "buf0block_hint.h"
+namespace buf {
+
+void Block_hint::buffer_fix_block_if_still_valid()
+{
+  /* To check if m_block belongs to the current buf_pool, we must
+  prevent freeing memory while we check, and until we buffer-fix the
+  block. For this purpose it is enough to latch any of the many
+  latches taken by buf_pool_t::resize().
+
+  Similar to buf_page_optimistic_get(), we must validate
+  m_block->page.id() after acquiring the hash_lock, because the object
+  may have been freed and not actually attached to buf_pool.page_hash
+  at the moment. (The block could have been reused to store a
+  different page, and that slice of buf_pool.page_hash could be protected
+  by another hash_lock that we are not holding.)
+
+  Finally, assuming that we have correct hash bucket latched, we must
+  validate m_block->state() to ensure that the block is not being freed. */
+  if (m_block)
+  {
+    const ulint fold= m_page_id.fold();
+    page_hash_latch *hash_lock= buf_pool.page_hash.lock<false>(fold);
+    if (buf_pool.is_uncompressed(m_block) && m_page_id == m_block->page.id() &&
+        m_block->page.state() == BUF_BLOCK_FILE_PAGE)
+      buf_block_buf_fix_inc(m_block, __FILE__, __LINE__);
+    else
+      clear();
+    hash_lock->read_unlock();
+  }
+}
+}  // namespace buf