[UBI UBIFS] replace vmalloc with kmalloc

[JiSheng Zhang]

Adrian Hunter <adrian.hunter at nokia.com> wrote:
> 
> vmalloc allows large (> 128KiB) buffers, but kmalloc doesn't.
> So we presently have no choice but to use vmalloc.

But vmalloced buffer can't be easily passed to DMA, is there better choice?

> 
> I do not know what hardware you have or exactly what driver you
> are using, but we have UBIFS on OneNAND using DMA.

An arm soc board, the controller driver hasn't been merged upstream.
> See drivers/mtd/onenand/omap2.c
>

One limit of the omap2.c is that the buffer passed to DMA can't be larger than
PAGESIZE?

Jisheng