buf_pool->mutex: Rename to buf_pool_mutex, so that the wrappers will have
to be used when changes are merged from other source trees.
buf_pool->zip_mutex: Rename to buf_pool_zip_mutex.
buf_pool_mutex_own(), buf_pool_mutex_enter(), buf_pool_mutex_exit():
Wrappers for buf_pool_mutex.
to BUF_BLOCK_ZIP_DIRTY (discarding the uncompressed page corresponding
to a modified compressed page that has not been flushed to disk).
buf_page_can_relocate(): New function, modelled after
buf_flush_ready_for_replace().
buf_LRU_free_block(): Allow the transition to BUF_BLOCK_ZIP_DIRTY.
buf_flush_insert_into_flush_list(): Make the prototype public.
buf_buddy_relocate(): Remove an unnecessary switch statement.
Use buf_page_can_relocate() instead of buf_flush_ready_for_replace().
buf_page_peek(): Made UNIV_INLINE.
Document UNIV_ZIP_DEBUG.
