Re: Should NVME_SC_INVALID_NS be translated to BLK_STS_IOERR instead of BLK_STS_NOTSUPP so that multipath(both native and dm) can failover on the failure?

[Jirong Feng <jirong.feng@easystack.cn>]

As far as I know, according to current implementation of function 
nvmet_parse_io_cmd() in drivers/nvme/target/core.c, nvmet_req_find_ns() 
is called before nvmet_check_ana_state(), so I believe currently nvmet 
is returning NVME_SC_INVALID_NS once namespace is disabled no matter if 
ANA is supported. In nvmet, a disabled namespace acts like it does not 
exist. nvmet_check_ana_state() requires req->ns, which is assigned in 
nvmet_req_find_ns(). If namespace is unknown, nvmet can't know the state 
of its ana group either.

So, to be better up to the specification, nvmet does need to 
differentiate a namespace is disabled or non-existent?

Moreover, even if nvmet returns NVME_SC_INVALID_FIELD to the host, the 
status code is still translated to BLK_STS_NOTSUPP, multipath won't 
retry either...


在 2023/12/5 13:18, Keith Busch 写道:
> On Tue, Dec 05, 2023 at 05:40:35AM +0100, Christoph Hellwig wrote:
>> On Mon, Dec 04, 2023 at 09:37:56PM -0700, Keith Busch wrote:
>>> So the controller through that path used to be able to access the
>>> Namespace, then suddenly lost ability to do so, but some other path can
>>> still access it if we retry on a failover/alternate path? I think your
>>> target is returning the wrong error code. It should be SCT/SC 303h,
>>> Asymmetric Access Persistent Loss (NVME_SC_ANA_TRANSITION), for what
>>> you're describing.
>> Yes, assuming ANA is actually supported by the controllers..
> Even without ANA, "Invalid Namespace" is still the wrong status code
> when dynamic namespace attachement is supported. If the namespace still
> exists in the subsystem but not attached to the controller processing a
> command (i.e. "inactive"), the return needs be Invalid Field in Command:
>
>    Specifying an inactive namespace identifier (refer to section 3.2.1.4)
>    in a command that uses the namespace identifier shall cause the
>    controller to abort the command with a status code of Invalid Field in
>    Command
>