Re: [PATCH v5 04/10] xfs: Reflink CoW-based atomic write support

[John Garry]

On 12/03/2025 13:45, Christoph Hellwig wrote:
> On Wed, Mar 12, 2025 at 09:13:45AM +0000, John Garry wrote:
> > > > +	if (error || (!*shared && !atomic_sw))
> > >
> > > And it's pnly used once.  Basically is is used to force COW, right?
> >
> > Yes, we force it. Indeed, I think that is term you used a long time ago in
> > your RFC for atomic file updates.
> >
> > But that flag is being used to set XFS_BMAPI_EXTSZALIGN, so feels like a bit
> > of a disconnect as why we would set XFS_BMAPI_EXTSZALIGN for "forced cow". I
> > would need to spell that out.
>
> Maybe use two flags for that even if they currently are set together?

ok, fine. Then it makes explaining why we set XFS_BMAPI_EXTSZALIGN for 
"force cow" a lot simpler in the code.

> Note that this would go away if we'd always align extsize hinted
> allocations, which I suspect is a good idea (even if I'm not 100% sure
> about it).

Sure

Cheers,
John