commit 204fd9506b0650ab400533ca1e222d0a700b9bb0
Author: Laurynas Biveinis <laurynas.biveinis@gmail.com>
Date:   Tue Jun 6 12:00:33 2017 +0300

    Fix bug 80496 / PS-3384 (buf_dblwr_init_or_load_pages now returns an error code, but caller not updated)
    
    buf_dblwr_init_or_load_pages, previously a void function, now returns
    a dberr_t, but its sole caller does not bother to check it. Fix by
    adding warn_unused_result function attribute and checking the return
    code in SysTablespace::read_lsn_and_check_flags.

diff --git a/storage/innobase/fsp/fsp0sysspace.cc b/storage/innobase/fsp/fsp0sysspace.cc
index ad71b1e51e2..70380ee1ec0 100644
--- a/storage/innobase/fsp/fsp0sysspace.cc
+++ b/storage/innobase/fsp/fsp0sysspace.cc
@@ -531,7 +531,10 @@ dberr_t SysTablespace::read_lsn_and_check_flags(lsn_t *flushed_lsn) {
 
   ut_a(it->order() == 0);
 
-  buf_dblwr_init_or_load_pages(it->handle(), it->filepath());
+  err = buf_dblwr_init_or_load_pages(it->handle(), it->filepath());
+  if (err != DB_SUCCESS) {
+    return (err);
+  }
 
   /* Check the contents of the first page of the
   first datafile. */
diff --git a/storage/innobase/include/buf0dblwr.h b/storage/innobase/include/buf0dblwr.h
index 689edcfc38b..8ffb1b0b7c9 100644
--- a/storage/innobase/include/buf0dblwr.h
+++ b/storage/innobase/include/buf0dblwr.h
@@ -56,6 +56,7 @@ bool buf_dblwr_create(void);
  function performs the necessary update operations. If we are in a crash
  recovery, this function loads the pages from double write buffer into memory.
  @return DB_SUCCESS or error code */
+MY_ATTRIBUTE((warn_unused_result))
 dberr_t buf_dblwr_init_or_load_pages(pfs_os_file_t file, const char *path);
 
 /** Process and remove the double write buffer pages for all tablespaces. */