On 2017/7/6 上午2:48, Christoph Hellwig wrote:

REQ_META should be purely a hint for blktrace, please don't use it
in the I/O path - that's what REQ_PRIO is for.
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Hi Christoph,

Then gfs2 breaks the above rule ?  in gfs2_metapath_ra() and
gfs2_dir_readahead(), only REQ_META is used in submit_bh(). It seems an
extra REQ_PRIO should be there.

I see 'commit 70246286e94c3 ("block: get rid of bio_rw and READA")' is
from you, could you please provide your point on adding REQ_PRIO on the
above 2 locations ?

IMHO another patch to add REQ_PRIO to gfs2 meta data read ahead code
path should be necessary.

Thanks.


-- 
Coly Li