Created attachment 123111 [details]
The snapshot target does not handle I/O barriers correctly so it should refuse
to process them. Otherwise code that relies on them working could lead to data
The mapping functions always pass reads through to the underlying devices
immediately, but writes may get delayed.
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.