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

[Christoph Hellwig]

On Thu, Sep 12, 2024 at 03:48:09PM +0100, John Garry wrote:
>
> 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.

bio_split is a bit of a mess - even NULL isn't very good at returning
what caused it to fail.  Maybe a switch to ERR_PTR and an audit of
all callers might be a good idea.