Re: [PATCH] block: fix residual byte count handling

From: Tejun Heo
Date: Tue Mar 04 2008 - 18:35:37 EST


FUJITA Tomonori wrote:
> Hmm, does SCSI mid-layer need to care about how many bytes the block
> layer allocates? I don't think that extra_len is NOT good_bytes.
>
> I think that the block layer had better take care about it (fix
> __end_that_request_first?).

Yeah, probably calling completion functions w/o bytes count is the right
thing to do but what I was talking about was what could break when the
semantics of rq->data_len changed. If we keep rq->data_len() ==
sum(sg), we keep it business as usual for all the rest except for the
device application layer if we don't we do the reverse and SCSI midlayer
completion was a good example, I think.

Things going the other way is fine with me but I at least want to hear a
valid rationale. Till now all I got is "because that's the true size"
which doesn't really make much sense to me.

Thanks.

--
tejun
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