[libvirt] [PATCH] Extra filesystem options during backend filesystem mount.

[Harshavardhana]

Hi Daniel,

Are you going to apply this to mainline?. Was just wondering if you have any
other concerns so that i could work on those if at all there are other
better ways you would have.

Thanks
--
Harshavardhana
Gluster - http://www.gluster.com/


On Sat, Jul 18, 2009 at 9:12 AM, Harshavardhana <harsha at gluster.com> wrote:

> Daniel,
>
>     Thanks for the pointers, i will keep this mind as and when the problem
> is fixed i will send a patch against those specific changes.
>
> Regards
> --
> Harshavardhana
> Z Research Inc http://www.zresearch.com/
>
>
>
> On Fri, Jul 17, 2009 at 11:58 PM, Daniel P. Berrange <berrange at redhat.com>wrote:
>
>> On Thu, Jul 16, 2009 at 08:24:09PM +0530, Harshavardhana wrote:
>> > Hi Daniel,
>> >
>> > On Thu, Jul 16, 2009 at 7:46 PM, Daniel P. Berrange <
>> berrange at redhat.com>wrote:
>> >
>> > > On Thu, Jul 16, 2009 at 06:06:25AM -0700, Harshavardhana wrote:
>> > > > New option index added to support -o options for various netfs.
>> > > > Currently added an option for glusterfs.
>> > >
>> > > What effect does it have  ? Or why do we want/need it
>> > >
>> >
>> > Options could be required for filesystem to have few enhaced handling at
>> the
>> > site where they will be under use. Correct approach for a configurable
>> will
>> > be a new "XML" option in this case.
>> >
>> > Regarding current patch:
>> > This is required for the glusterfs to work properly with VM's.  Right
>> now
>> > there is a
>> > problem/difficulty in using direct-io based mechanism in the fuse kernel
>> > module
>> > when used with "XEN" in its "tap:aio" framework, we have seen xen vms
>> hang
>> > over glusterfs or any fuse based filesystem due to fact that fuse module
>> > doesn't yet support "aio" with O_DIRECT internally as a kernel module.
>> To
>> > have a work around fix we have to hardcode this value due to its usage
>> in
>> > case of VM's.
>> >
>> > We are currently fixing this problem by fixing directly O_DIRECT problem
>> in
>> > fuse. Which will be available in later releases for kernel.
>>
>> ACK, I see why you need this for the current releases of kernel/glusterfs.
>>
>> As & when this problem is fixed we'll need to either remove this, or
>> provide a way to turn it off again. I don't think this is the kind of
>> tunable that should be exposed in the XML, since this is really just a
>> hack to work around a bug in a specific releases. Someone using libvirt
>> has no way to decide whether the hack is needed or not, so making them
>> set it in the XML would not be desirable. One possibility would be to
>> have a config file /etc/libvirt/storage.conf for controlling certain
>> options like this per host.
>>
>> Regards,
>> Daniel
>> --
>> |: Red Hat, Engineering, London   -o-
>> http://people.redhat.com/berrange/ :|
>> |: http://libvirt.org  -o-  http://virt-manager.org  -o-
>> http://ovirt.org :|
>> |: http://autobuild.org       -o-
>> http://search.cpan.org/~danberr/ <http://search.cpan.org/%7Edanberr/> :|
>> |: GnuPG: 7D3B9505  -o-  F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505
>> :|
>>
>>
>
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