This helper allows reinserting a bio into a new queue without much
overhead, but requires all queue limits to be the same for the upper
and lower queues, and it does not provide any recursion preventions,
which requires the caller to not split the bio.
Isn't the same limits constraint too restrictive?
Say I have two paths to the same namespace via two different HBAs, each
with its own virt_boundary capability for example? That would require us
to split failover bio wouldn't it?
Uh oh - different transports for the same subsystem will be intereting.
For one it's not specified anywhere so I'd like to kick off a discussion
on the working group mailing list about it.
Indeed that would be interesting, but I wasn't referring to different
transports, even the same transport can have different capabilities
(for example CX4 and CX4 devices on the same host).
That being said ->make_request basically doesn't care about actual
limits at all, it mostly care about support features (e.g. discard, fua,
etc). So I think a lot of these limits could porbably be lifted,
but I'd need to add the check to generic_make_request_checks back.
Different virt_boundary capabilities will trigger bio splits which
can make make_request blocking (due to lack of tags).
