md/raid5: For odirect-write performance, do not set STRIPE_PREREAD_ACTIVE.
'sync' writes set both REQ_SYNC and REQ_NOIDLE. O_DIRECT writes set REQ_SYNC but not REQ_NOIDLE. We currently assume that a REQ_SYNC request will not be followed by more requests and so set STRIPE_PREREAD_ACTIVE to expedite the request. This is appropriate for sync requests, but not for O_DIRECT requests. So make the setting of STRIPE_PREREAD_ACTIVE conditional on REQ_NOIDLE rather than REQ_SYNC. This is consistent with the documented meaning of REQ_NOIDLE: __REQ_NOIDLE, /* don't anticipate more IO after this one */ Signed-off-by: Jianpeng Ma <majianpeng@gmail.com> Signed-off-by: NeilBrown <neilb@suse.de>
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@ -4135,7 +4135,7 @@ static void make_request(struct mddev *mddev, struct bio * bi)
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finish_wait(&conf->wait_for_overlap, &w);
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set_bit(STRIPE_HANDLE, &sh->state);
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clear_bit(STRIPE_DELAYED, &sh->state);
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if ((bi->bi_rw & REQ_SYNC) &&
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if ((bi->bi_rw & REQ_NOIDLE) &&
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!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
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atomic_inc(&conf->preread_active_stripes);
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mddev_check_plugged(mddev);
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