Re: [PATCH V2 2/7] md: add accounting_bio for raid0 and raid5

On Fri, May 21, 2021 at 08:55:16AM +0800, Guoqing Jiang wrote:

Let's introduce accounting_bio which checks if md needs clone the bio
for accounting.

And add relevant function to raid0 and raid5 given both don't have
their own clone infrastrure, also checks if it is split bio.

Please don't add another indirect call in the I/O submission fast path.
With Spectre mitigations these are really slow, and also are hard to
follow.

I think moving the call to allocate the accounting bio clone entirely
into the personalities is probably the cleanest approach without any
of these downsides.