Re: [PATCH RFC 2/4] xfs: logically separate iomap range from allocation range

[Brian Foster <bfoster@redhat.com>]

On Tue, Nov 15, 2016 at 06:18:04AM -0800, Christoph Hellwig wrote:
> On Tue, Nov 08, 2016 at 03:27:34PM -0500, Brian Foster wrote:
> > The xfs_file_iomap_begin_delay() function currently converts the bmbt
> > record output from the xfs_bmapi_reserve_delalloc() call to the iomap
> > mapping for the higher level iomap code. In preparation to reuse
> > xfs_file_iomap_begin_delay() for data fork and COW fork allocation,
> > logically separate the iomap mapping provided to the caller from the
> > bmbt record returned by xfs_bmapi_reserve_delalloc().
> > 
> > This is necessary because while COW reservation involves delalloc
> > allocation to the COW fork, the mapping returned to the caller must
> > still refer to the shared blocks from the data fork. Note that this
> > patch does not change behavior in any way.
> 
> On it's own this patch looks highly confusing.  I'll keep reading
> the rest of the series if it makes more sense with that, but in doubt
> it probably should be merged into whatever patches it helps with.

Heh, Ok. I'll revisit this when the rest of the code is more fleshed
out.

Brian