Re: [PATCH 06/10] xfs: remove ->b_offset handling for page backed buffers

On Thu, May 27, 2021 at 04:09:58PM -0700, Darrick J. Wong wrote:

On Thu, May 27, 2021 at 08:47:18AM +1000, Dave Chinner wrote:

quoted

From : Christoph Hellwig [off-list ref]

->b_offset can only be non-zero for _XBF_KMEM backed buffers, so
remove all code dealing with it for page backed buffers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
[dgc: modified to fit this patchset]
Signed-off-by: Dave Chinner <redacted>

I think it's the case that the only time we'd end up with a nonzero
b_offset is if the kmem_alloc returns a slab object in the middle of a
page, right?  i.e. vmalloc is supposed to give us full pages, and we
hope that nobody ever sells a device with a 64k dma alignment...?

So much would break with such a device :/

Assuming that's right,

Yup, it is.

Reviewed-by: Darrick J. Wong <djwong@kernel.org>

Ta.

-Dave.
-- 
Dave Chinner
david@fromorbit.com