linux-kernel - Re: [PATCH blktests v1 2/3] nvme/rc: Avoid triggering host nvme-cli autoconnect

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Message-ID: <875b1903-bca8-8c6e-79d7-506313bbd56d@suse.de>
Date:   Thu, 13 Jul 2023 12:14:14 +0200
From:   Hannes Reinecke <hare@...e.de>
To:     Max Gurtovoy <mgurtovoy@...dia.com>,
        Daniel Wagner <dwagner@...e.de>
Cc:     linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-block@...r.kernel.org, Chaitanya Kulkarni <kch@...dia.com>,
        Shin'ichiro Kawasaki <shinichiro.kawasaki@....com>,
        Sagi Grimberg <sagi@...mberg.me>,
        James Smart <jsmart2021@...il.com>,
        Martin Belanger <Martin.Belanger@...l.com>
Subject: Re: [PATCH blktests v1 2/3] nvme/rc: Avoid triggering host nvme-cli
 autoconnect

On 7/13/23 10:49, Max Gurtovoy wrote:
> 
> 
> On 13/07/2023 9:00, Hannes Reinecke wrote:
>> On 7/13/23 02:12, Max Gurtovoy wrote:
>>>
>>>
>>> On 12/07/2023 15:04, Daniel Wagner wrote:
>>>> On Mon, Jul 10, 2023 at 07:30:20PM +0300, Max Gurtovoy wrote:
>>>>>
>>>>>
>>>>> On 10/07/2023 18:03, Daniel Wagner wrote:
>>>>>> On Mon, Jul 10, 2023 at 03:31:23PM +0300, Max Gurtovoy wrote:
>>>>>>> I think it is more than just commit message.
>>>>>>
>>>>>> Okay, starting to understand what's the problem.
>>>>>>
>>>>>>> A lot of code that we can avoid was added regarding the --context 
>>>>>>> cmdline
>>>>>>> argument.
>>>>>>
>>>>>> Correct and it's not optional to get the tests passing for the fc 
>>>>>> transport.
>>>>>
>>>>> why the fc needs the --context to pass tests ?
>>>>
>>>> A typical nvme test consists out of following steps (nvme/004):
>>>>
>>>> // nvme target setup (1)
>>>>     _create_nvmet_subsystem "blktests-subsystem-1" "${loop_dev}" \
>>>>         "91fdba0d-f87b-4c25-b80f-db7be1418b9e"
>>>>     _add_nvmet_subsys_to_port "${port}" "blktests-subsystem-1"
>>>>
>>>> // nvme host setup (2)
>>>>     _nvme_connect_subsys "${nvme_trtype}" blktests-subsystem-1
>>>>
>>>>     local nvmedev
>>>>     nvmedev=$(_find_nvme_dev "blktests-subsystem-1")
>>>>     cat "/sys/block/${nvmedev}n1/uuid"
>>>>     cat "/sys/block/${nvmedev}n1/wwid"
>>>>
>>>> // nvme host teardown (3)
>>>>     _nvme_disconnect_subsys blktests-subsystem-1
>>>>
>>>> // nvme target teardown (4)
>>>>     _remove_nvmet_subsystem_from_port "${port}" "blktests-subsystem-1"
>>>>     _remove_nvmet_subsystem "blktests-subsystem-1"
>>>>
>>>>
>>>> The corresponding output with --context
>>>>
>>>>   run blktests nvme/004 at 2023-07-12 13:49:50
>>>> // (1)
>>>>   loop0: detected capacity change from 0 to 32768
>>>>   nvmet: adding nsid 1 to subsystem blktests-subsystem-1
>>>>   nvme nvme2: NVME-FC{0}: create association : host wwpn 
>>>> 0x20001100aa000002  rport wwpn 0x20001100aa000001: NQN 
>>>> "blktests-subsystem-1"
>>>>   (NULL device *): {0:0} Association created
>>>>   [174] nvmet: ctrl 1 start keep-alive timer for 5 secs
>>>> // (2)
>>>>   nvmet: creating nvm controller 1 for subsystem 
>>>> blktests-subsystem-1 for NQN 
>>>> nqn.2014-08.org.nvmexpress:uuid:0f01fb42-9f7f-4856-b0b3-51e60b8de349.
>>>>   [374] nvmet: adding queue 1 to ctrl 1.
>>>>   [1138] nvmet: adding queue 2 to ctrl 1.
>>>>   [73] nvmet: adding queue 3 to ctrl 1.
>>>>   [174] nvmet: adding queue 4 to ctrl 1.
>>>>   nvme nvme2: NVME-FC{0}: controller connect complete
>>>>   nvme nvme2: NVME-FC{0}: new ctrl: NQN "blktests-subsystem-1"
>>>> // (3)
>>>>   nvme nvme2: Removing ctrl: NQN "blktests-subsystem-1"
>>>> // (4)
>>>>   [1138] nvmet: ctrl 1 stop keep-alive
>>>>   (NULL device *): {0:0} Association deleted
>>>>   (NULL device *): {0:0} Association freed
>>>>   (NULL device *): Disconnect LS failed: No Association
>>>>
>>>>
>>>> and without --context
>>>>
>>>>   run blktests nvme/004 at 2023-07-12 13:50:33
>>>> // (1)
>>>>   loop1: detected capacity change from 0 to 32768
>>>>   nvmet: adding nsid 1 to subsystem blktests-subsystem-1
>>>>   nvme nvme2: NVME-FC{0}: create association : host wwpn 
>>>> 0x20001100aa000002  rport wwpn 0x20001100aa000001: NQN 
>>>> "nqn.2014-08.org.nvmexpress.discovery"
>>>
>>> why does this association to discovery controller created ? because 
>>> of some system service ?
>>>
>> Yes. There are nvme-autoconnect udev rules and systemd services 
>> installed per default (in quite some systems now).
>> And it's really hard (if not impossible) to disable these services (as 
>> we cannot be sure how they are named, hence we wouldn't know which 
>> service to disable.
> 
> Right. We shouldn't disable them IMO.
> 
>>
>>> can we configure the blktests subsystem not to be discovered or add 
>>> some access list to it ?
>>>
>> But that's precisely what the '--context' thing is attempting to do ...
> 
> I'm not sure it is.
> 
> Exposing the subsystem is from the target configuration side.
> Additionally, the --context (which is in the initiator/host side), 
> according to Daniel, is there to distinguish between different 
> invocations. I proposed that blktests subsystem will not be part of 
> discoverable fabric or protected somehow by access list. Therefore, no 
> additional invocation will happen.
> 
Hmm. Maybe we can tweak blktest to use it's own HostNQN, and always pass 
that for any nvme-cli call.
Daniel?

Cheers,

Hannes