Re: [PATCH v7 1/1] nvmet: support reservation feature

[Guixin Liu <kanie@linux.alibaba.com>]

在 2024/3/13 05:31, Sagi Grimberg 写道:
> So I understand from you that there is out-of-band mechanism for fence 
> guarantee?
>
> In any event, Christoph reminded me that preempt and abort is 
> mandatory, so we cannot
> get away without doing it.
>
Agree.
> I suggest to introduce a per-ns-per-controller percpuref, with an 
> xarray that is rcu protected.

I will implement it in v9, and I also think that we should a 
time-limited wait.

>
> btw, I also think that reservations on nsid=0xffffffff should also 
> work. IIRC there were at least
> two use-cases that would have benefited from reservations on all 
> subsystem namespaces.
> It can also be a lot more lightweight to implement that (outside of 
> conflicting reservations checks). 

You mean one host can reserve all of namespaces by sending one 
reservation command?

Well, Could you please tell me which two use-cases?

I think this will make the target code too complicated, because the 
reservation situation on each

namespace may different, we should handle it one-by-one, and if failed 
in middle, we should revert

the handled namespaces.

Best regards,

Guixin Liu