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

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

>>
>> What do you think Sagi? Or may be we can declare that 
>> preempt_and_abort is not supported, just
>>
>> like SPDK does.
>
> It can definitely come incrementally, but at the very least it should 
> be incorrectly supported.
>
> Out of curiosity, doesn't your use-case need a fencing protection 
> against inflight I/Os reordering during
> preemption?

The cluster use stonith(shoot the other node in the head) to protect 
sources,

and the backend storage(our storage system goes like this, so does disk 
firmware I think.)

can process write I/O operations on a first-come,first-served basis if 
the range of

data accessed by two I/O operation overlaps, for example, hostB preempt 
and abort

hostA, then host B send I/Os, the backend storage will handle hostA's 
I/O first(by the timestamp).

Best regards,

Guixin Liu