Re: [PATCH V10 17/19] block: don't use bio->bi_vcnt to figure out segment number

From: Christoph Hellwig
Date: Fri Nov 16 2018 - 08:55:16 EST


On Thu, Nov 15, 2018 at 04:53:04PM +0800, Ming Lei wrote:
> It is wrong to use bio->bi_vcnt to figure out how many segments
> there are in the bio even though CLONED flag isn't set on this bio,
> because this bio may be splitted or advanced.
>
> So always use bio_segments() in blk_recount_segments(), and it shouldn't
> cause any performance loss now because the physical segment number is figured
> out in blk_queue_split() and BIO_SEG_VALID is set meantime since
> bdced438acd83ad83a6c ("block: setup bi_phys_segments after splitting").

Looks good, but shouldn't this go to the beginning of the series?

Reviewed-by: Christoph Hellwig <hch@xxxxxx>