Re: [PATCH RFC 4/7] md/raid10: convert read/write to use bio_submit_split()

[Christoph Hellwig]

On Tue, Aug 26, 2025 at 06:35:10PM +0100, anthony wrote:
> On 26/08/2025 10:14, Yu Kuai wrote:
> > > Umm, that's actually a red flag.  If a device guarantees atomic behavior
> > > it can't just fail it.  So I think REQ_ATOMIC should be disallowed
> > > for md raid with bad block tracking.
> > > 
> > 
> > I agree that do not look good, however, John explained while adding this
> > that user should retry and fallback without REQ_ATOMIC to make things
> > work as usual.
> 
> Whether a device promises atomic write is orthogonal to whether that write
> succeeds - it could fail for a whole host of reasons, so why can't "this is
> too big to be atomic" just be another reason for failing?

Too big to be atomic is a valid failure reason.  But the limit needs
to be documented in the queue limits beforehand.