[libvirt] [PATCH v2 0/6] Allow adding mountOpts to the storage pool mount command

John Ferlan jferlan at redhat.com
Wed Jan 9 19:31:11 UTC 2019


[...]

>>> For the general nosuid, nodev flags, I think we can do something like we
>>> have for the <features/> element in the domain XML.
>>>
>>
>> So that means to me that every option currently possible in mount would
>> need to be listed.  Doesn't that feel excessive?  Not that mount changes
>> that often, but I would think it's awfully painful to take that route.
>> Especially for some of the "more complicated" mount options.
> 
> The mount command options are a tiny, trivial set compared to QEMU
> command line options. The goal here is not to have simple libvirt
> code, rather is to have portable & simple application code. Libvirt
> exists to provide an abstraction layer over OS specific commands
> line "mount" which can have different syntax on each OS. eg FreeBSD
> mount command options may differ from Linux mount command options.

And this last line is the biggest concern over providing or "by default"
adding "-o nosuid,nodev,noexec" for NFS mount command line.

Secondary to that is the "what if" by doing so we break some existing
configuration for some reason that was making use of a pool volume in
some really strange manner that we didn't expect just because one of
those mount options wasn't set by default. Not that it seems the 3
mentioned ones would cause such pain, but the precedence of adding
options by default in general.

> 
> I'm not suggesting implementing support for every single mount
> option though. Only those that we actually have a compelling
> reason to support, just as we've not implemented every single
> QEMU arg.
> 

Understood. Of course as soon a couple are implemented, someone else's
favorite is desired, etc. It's the picking and choosing which are
compelling enough to support vs. just allowing or even providing a
supportable mechanism to allow arbitrary command options vs.
implementing "some" and leaving the rest to be added via namespace.

Right now the "some" are:

    nfsvers='n'  [add only if new XML exists]
    nosuid
    nodev
    noexec

and maybe additionally 'ro' if [new] <readonly/> was set.

Just trying to get all the "parameters" set before starting a v3...

John

[...]




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