[dm-devel] [PATCH 1/2] dm: Make flush bios explicitely sync

[Mike Snitzer]

On Wed, May 31 2017 at  3:44am -0400,
Jan Kara <jack at suse.cz> wrote:

> Commit b685d3d65ac7 "block: treat REQ_FUA and REQ_PREFLUSH as
> synchronous" removed REQ_SYNC flag from WRITE_{FUA|PREFLUSH|...}
> definitions.  generic_make_request_checks() however strips REQ_FUA and
> REQ_PREFLUSH flags from a bio when the storage doesn't report volatile
> write cache and thus write effectively becomes asynchronous which can
> lead to performance regressions
> 
> Fix the problem by making sure all bios which are synchronous are
> properly marked with REQ_SYNC.
> 
> CC: Mike Snitzer <snitzer at redhat.com>
> CC: dm-devel at redhat.com
> Fixes: b685d3d65ac791406e0dfd8779cc9b3707fea5a3
> CC: stable at vger.kernel.org
> Signed-off-by: Jan Kara <jack at suse.cz>

thanks, staged for 4.12-rc4