Re: [PATCH 02/10] iomap: improve shared block detection in iomap_unshare_iter

Christoph Hellwig
2024-08-28T04:49:33Z

On Tue, Aug 27, 2024 at 09:21:49AM -0700, Darrick J. Wong wrote:
> > For writes it usually means out of place write, but for reporting
> > it gets translated to the FIEMAP_EXTENT_SHARED flag or is used to
> > reject swapon. And the there is black magic in DAX.
>
> Hee hee. Yeah, let's leave IOMAP_F_SHARED alone; an out of place write
> can be detected by iter->srcmap.type != HOLE.

I can probably come up with a comment that includes the COWextsize hints
in the definition of out of place writes and we should be all fine..