[systemd-devel] help: unmounting iscsi xfs filesystem without using netdev in /etc/fstab

Tue Aug 27 18:19:56 UTC 2019

Thanks but I did not misinterpret, I know _netdev is used as a 
hint/keyword tag. I was speaking in general terms regarding using 
_netdev.  Yes I also believe the delay is caused by network-online as 
well.  Even though I figured things out by myself, I still want to thank 
others that offered suggestions and tried to help. Thanks again.

Tony

On 8/27/19 11:06 AM, Andrei Borzenkov wrote:
> 27.08.2019 18:55, Tony Rodriguez пишет:
>> Interesting that you mentioned the following. I actually added logic to
>> do something like this early yesterday.   Will discuss with my team to
>> see if this is good enough.  I'd rather not bypass _netdev either. Feels
>> like I am re-eventing the wheel. I think the main issue regarding using
>> _netdev is the amount of time it takes to check/mount iscsi devices.
>> Believe it waits up to 90 seconds to timeout for an iscsi
>> device/filesystem and I am not sure this can be bypassed.  Is it
>> possible to limit the amount of time _netdev will take?
> You seem to seriously misinterpret what you see. _netdev does not "do"
> anything. It only affects which After/Before/Wants directives are added
> to mount unit definition - nothing more. If you see 90 seconds timeout,
> most likely one of units that mount is ordered After fails to start -
> and my educated guess is that it is related to network-online.
>
>
>>    I tried setting
>> x-systemd.device-timeout and x-systemd.mount-timeout with _netdev in
>> /etc/fstab but it didn't seem to work.  It also didn't propagate to
>> /run/systemd/generators/remote-fs-target.requires   I believe the
>> systemd document mentioned such settings are ignored.
>>
>> "I haven't been following your earlier threads too closely, but if you're
>> stuck with stupid fstab requirements why not just bypass them with
>> altogether with drop-in:
>>
>>      # path-to-mountpoint.mount.d/20-Options.conf
>>      [Mount]
>>      Options=_netdev"
>>
>>
>>
>> On 8/27/19 2:33 AM, Michael Chapman wrote:
>>> On Tue, 27 Aug 2019, Tony Rodriguez wrote:
>>>> Managed to detect/mount iscsi devices without using _netdev keyword in
>>>> /etc/fstab.  Made changes within
>>>> src/fstab-generator/ftstab-generator.c and it
>>>> seems to work.  The only problem is during shutdown/reboot, my iscsi xfs
>>>> filesystem does not unmount cleanly before the network/iscs
>>>> service/system is
>>>> shutdown.  When this happens I receive a xfs error/warning.
>>>>
>>>> However this doesn't happen when _netdev is specified in /etc/fstab
>>>> for my
>>>> iscsi device.  Seems _netdev handles management of mounts/unmounts
>>>> before
>>>> killing things off.  How exactly does _netdev manage unmounting
>>>> filesystems
>>>> during a shutdown/reboot?
>>> One of the "default dependencies" for a mount unit that systemd thinks is
>>> a network filesystem is After=network.target. During shutdown, this
>>> ensures the filesystem is unmounted before networking is brought down:
>>>
>>>      
>>> https://github.com/systemd/systemd/blob/fef40ceb5dfbb76d4733e579846a380a224efd55/src/core/mount.c#L455-L482
>>>
>>>
>>> If you're not using the _netdev keyword, and systemd does not otherwise
>>> think this is a remote filesystem, you will need to add this dependency
>>> manually. You'll probably also want:
>>>
>>>       Wants=network-online.target
>>>       After=network-online.target
>>>
>>> to match the code linked above.
>>>
>>>>     I would like to invoke that same netdev unmount
>>>> code/logic myself from within systemd source but without using the
>>>> _netdev
>>>> keyword. Unfortunately it is a requirement to not use _netdev within
>>>> /etc/fstab for iscsi.  Seems _netdev takes a long time to timeout and
>>>> continue
>>>> when unable to mount.
>>> I haven't been following your earlier threads too closely, but if you're
>>> stuck with stupid fstab requirements why not just bypass them with
>>> altogether with drop-in:
>>>
>>>       # path-to-mountpoint.mount.d/20-Options.conf
>>>       [Mount]
>>>       Options=_netdev
>>>
>>> Plus any other options you may need, of course; this directive is not
>>> "list-valued", so you can't use it to add just one option.
>>>
>>>> Checked src/core/mount.c and src/core/unmount.c but not sure what to
>>>> do to
>>>> duplicate how _netdev manages unmounting before the system is
>>>> shutdown or
>>>> rebooted.  Do I need a special before and after keyword in /etc/fstab
>>>> so my
>>>> xfs filesystems is unmounted before shutting down the iscsi
>>>> service/network/system?  If so, will such keywords also propagate to
>>>> /run/systemd/generator/remote-fs-target.requires?
>>>>
>>>>
>>>> Thanks,
>>>> Tony
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