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    md: deal with merge_bvec_fn in component devices better. · 627a2d3c
    NeilBrown 提交于
    If a component device has a merge_bvec_fn then as we never call it
    we must ensure we never need to.  Currently this is done by setting
    max_sector to 1 PAGE, however this does not stop a bio being created
    with several sub-page iovecs that would violate the merge_bvec_fn.
    
    So instead set max_segments to 1 and set the segment boundary to the
    same as a page boundary to ensure there is only ever one single-page
    segment of IO requested at a time.
    
    This can particularly be an issue when 'xen' is used as it is
    known to submit multiple small buffers in a single bio.
    Signed-off-by: NNeilBrown <neilb@suse.de>
    Cc: stable@kernel.org
    627a2d3c
multipath.c 14.9 KB