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    md: Make flush bios explicitely sync · 5a8948f8
    Jan Kara 提交于
    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.
    
    CC: linux-raid@vger.kernel.org
    CC: Shaohua Li <shli@kernel.org>
    Fixes: b685d3d6
    CC: stable@vger.kernel.org
    Signed-off-by: NJan Kara <jack@suse.cz>
    Signed-off-by: NShaohua Li <shli@fb.com>
    5a8948f8
raid5-cache.c 86.5 KB