[PATCH rfc 0/3] add support to discovery async event notifications

[sagi@grimberg.me (Sagi Grimberg)]

>> fyi - the udev script fc uses passes arguments (HOST_TRADDR and 
>> TRADDR) from the event into the systemd service. Actually, it creates 
>> an instance of the service based on the names built from those arguments.
>>
>> Passing different arguments beyond that seemed rather difficult. For 
>> that I was assuming the instance arguments would have to be parsed, 
>> and a system file extracted, to obtain any variable values (such as 
>> device-specific connect timeouts, or queue count limits, etc).
>>
> That is precisely where I'm scratching my head now.
> Essentially the systemd '@' thingie allows you to pass exactly _one_ 
> argument. Sadly we have several options to pass, not just one.
> We could reduce the number of options by having per-transport services,
> but then we require at least two arguments to be passed (host traddr and 
> traddr for FC, traddr, trsvcid, and adrfam for RDMA).
>  From what I can see we can try to:
> 1) escape the arguments so that they appear as one string to systemd, 
> and then de-escaping them in the service file. Works without 
> modification to the code, but then you always have to invoke the shell 
> to handle escaping/de-escaping.

I don't see a problem with that..

> 2) preformat the nvme option string, and pass that as argument for the 
> systemd service. Which actually would get rid of the need for using 
> nvme-cli, too, as we could just write the string into the device node.
> Will be looking into it.

Where would the option string be preformatted?