Re: [PATCH RFC 4/4] md/raid0: Atomic write support

[John Garry]

On 12/09/2024 14:18, Christoph Hellwig wrote:
> On Tue, Sep 03, 2024 at 03:07:48PM +0000, John Garry wrote:
> >   	if (sectors < bio_sectors(bio)) {
> > -		struct bio *split = bio_split(bio, sectors, GFP_NOIO,
> > +		struct bio *split;
> > +
> > +		if (bio->bi_opf & REQ_ATOMIC)
> > +			return false;
> I guess this is the erroring out when attempting to split the request.

I actually now think that I should change bio_split() to return NULL for 
splitting a REQ_ATOMIC, like what do for ZONE_APPEND - calling 
bio_split() like this is a common pattern in md RAID personalities. 
However, none of the md RAID code check for a NULL split, which they 
really should, so I can make that change also.

> Can you add a comment to explain that and why it can't happen for the
> normal I/O patterns?

ok, will do.

Cheers,
John