Re: [PATCH]: Rename REQ_COPY_USER to more descriptive REQ_HAS_TAIL_SPACE_FOR_PADDING

From: Vladislav Bolkhovitin
Date: Thu Jul 09 2009 - 14:30:33 EST


Jens Axboe, on 07/09/2009 10:17 PM wrote:
On Thu, Jul 09 2009, Vladislav Bolkhovitin wrote:
Currently names of REQ_COPY_USER and __REQ_COPY_USER constants are confusing,
because they actually mean that the buffer for the corresponding requests
has space in the tail for padding in case of DMA padding restrictions.

No, that's not what it means, the fact that there's padding room is a
side effect of the map type. So I'd suggest adding a comment above that
if {} in blk_rq_map_sg(), something that should have been there from the
beginning.

Can you elaborate a bit more about what REQ_COPY_USER should mean, please?

As far as I can see from the sources, currently it's used to only to determine if there is the padding space. Maybe, the original meaning doesn't make sense anymore?

Thanks,
Vlad



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