Re: [PATCH RFCv2 2/4] iomap: optional zero range dirty folio processing

[Brian Foster <bfoster@redhat.com>]

On Tue, Jan 14, 2025 at 09:47:28PM -0800, Christoph Hellwig wrote:
> On Mon, Jan 13, 2025 at 09:32:37AM -0500, Brian Foster wrote:
> > In turn, this means that extending write zero range would have either
> > physically zeroed delalloc extents or skipped unwritten blocks,
> > depending on the situation. Personally, I don't think it really matters
> > which as there is no real guarantee that "all blocks not previously
> > written to are unwritten," for example, but rather just that "all blocks
> > not written to return zeroes on read."
> 
> Yes.
> 
> > For that reason, I'm _hoping_
> > that we can keep this simple and just deal with some potential spurious
> > zeroing on folios that are already dirty, but I'm open to arguments
> > against that.
> 
> I can't see one.  But we really should fine a way to write all this
> including the arguments for an again down.
> 

Indeed. If the first non-rfc pass ultimately makes this tradeoff, I'll
plan to document the behavior in the code and the reasoning and
tradeoffs in the commit log so it can be reviewed.

Brian