[kernel-hardening] Re: [PATCH v2 15/30] xfs: Define usercopy region in xfs_inode slab cache

[Christoph Hellwig <hch@infradead.org>]

On Wed, Aug 30, 2017 at 06:05:58PM +1000, Dave Chinner wrote:
> Ok, that's sounds like it'll fit right in with what I've been
> prototyping for the extent code in xfs_bmap.c. I can make that work
> with a cursor-based lookup/inc/dec/ins/del API similar to the bmbt
> API. I've been looking to abstract the extent manipulations out into
> functions that modify both trees like this:
> 
> [note: just put template code in to get my thoughts straight, it's
> not working code]

FYI, I've got somewhat working changes in that area (still has bugs
but a few tests pass :)), what I'm doing is to make sure all of
the xfs_bmap_{add,del}_extent_* routines fully operate on xfs_bmbt_irec
structures that they acquire through the xfs_bmalloca structure or
from xfs_iext_get_extent and update using xfs_iext_update_extent.
A nice fallout from that is that we can change the prototypes for
xfs_bmbt_lookup_* and xfs_bmbt_update to take a xfs_bmbt_irec
as well instead of taking the individual arguments.  That should
help with your next step cleanups a bit.