Re: remove block layer bounce buffering for MMC

[Christoph Hellwig]

On Mon, Jan 14, 2019 at 04:52:40PM +0000, Robin Murphy wrote:
> One general point for the kmap() conversions - it's not obvious (to me at 
> least) whether or how that would work for a segment where sg->length > 
> PAGE_SIZE. Or is there some cast-iron guarantee from the MMC mid-layer that 
> it will never let the block layer generate such things in the first place?

None of this will with such segments.  But yes, I guess the old case
could have worked as long as any physical contigous ranges are also
virtually contigous.  So we might have to throw in a page size segment
boundary here.