• Jan Kara's avatar
    dm: make flush bios explicitly sync · ff0361b3
    Jan Kara authored
    Commit b685d3d6 ("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.
    
    Fixes: b685d3d6 ("block: treat REQ_FUA and REQ_PREFLUSH as synchronous")
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarJan Kara <jack@suse.cz>
    Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
    ff0361b3
dm.c 65.1 KB