Re: [PATCH V2] block: correctly fallback for zeroout

[Sitsofe Wheeler]

On Tue, Jun 14, 2016 at 10:14:50PM -0400, Martin K. Petersen wrote:
> >>>>> "Christoph" == Christoph Hellwig <hch@xxxxxxxxxxxxx> writes:
> 
> Christoph> And I'd much prefer to get this right now.  It's not like
> Christoph> this is recently introduced behavior.
> 
> Unfortunately there are quite a few callers of blkdev_issue_discard()
> these days. Some of them ignore the return value but not all of
> them. I'm concerned about causing all sorts of breakage if we suddenly
> start returning errors various places in the stable trees.

This is true. We have problematic behaviour in stable kernels today so
there needs to be a "least intrusive" workaround which changes the
behaviour as little as possible for those. I would say that means
maintaining the current -EOPNOTSUPP behaviour in those kernels
regardless of what goes into master.

-- 
Sitsofe | http://sucs.org/~sits/