RE: [PATCH] Cachefiles, mpage_cleardirty addtition, west bridge related

From: David Cross
Date: Wed Sep 08 2010 - 12:51:53 EST



> From: dhowells@xxxxxxxxxx [mailto:dhowells@xxxxxxxxxx]

> David Cross <david.cross@xxxxxxxxxxx> wrote:

> > This patch adds the mpage_cleardirty function to the cachefiles >
implementation in the kernel.

> Ummm... How is this used by cachefiles? Nothing in this patch actually >
uses
> mpage_cleardirty().

This is used by the current west bridge driver in the linux-next tree,
marked as BROKEN at the moment. It is used in order to clear dirty pages
from the page cache for a specific file after it has been allocated. This
allows west bridge to transfer data from USB to storage directly without
requiring that the file data path go through the CPU. The easiest way to
think of this is that it allows for direct file based DMA. Please let me
know if you have any additional questions or concerns on this.
Thanks,
David


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