Implementing quota support on Linux without block device as backing store ? / was: RE: [PATCH 1/8] quota: Allow to pass mount path to quotactl

Implementing quota support on Linux without block device as backing store ? / was: RE: [PATCH 1/8] quota: Allow to pass mount path to quotactl

[Mainz, Roland]

Sascha Hauer wrote:
> This patch introduces the Q_PATH flag to the quotactl cmd argument.
> When given, the path given in the special argument to quotactl will be the
> mount path where the filesystem is mounted, instead of a path to the block
> device.
> This is necessary for filesystems which do not have a block device as backing
> store. Particularly this is done for upcoming UBIFS support.

Just curious: Did you check how NFSv4 (also a filesystem without block device as backing store...)  implemented quota support ? Maybe there is already a solution...

----

Bye,
Roland
-- 
Roland Mainz, MAA/CAS
Eckelmann AG, Berliner Str. 161, 65205 Wiesbaden
Telefon +49/611/7103-661, Fax +49/611/7103-133
r.mainz@eckelmann.de

Eckelmann Group - Source of inspiration


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Re: Implementing quota support on Linux without block device as backing store ? / was: RE: [PATCH 1/8] quota: Allow to pass mount path to quotactl

[Jan Kara]

On Tue 04-02-20 15:07:31, Mainz, Roland wrote:
> Sascha Hauer wrote:
> > This patch introduces the Q_PATH flag to the quotactl cmd argument.
> > When given, the path given in the special argument to quotactl will be the
> > mount path where the filesystem is mounted, instead of a path to the block
> > device.
> > This is necessary for filesystems which do not have a block device as backing
> > store. Particularly this is done for upcoming UBIFS support.
> 
> Just curious: Did you check how NFSv4 (also a filesystem without block
> device as backing store...)  implemented quota support ? Maybe there is
> already a solution...

Well, NFS does not really implement quota support. It relies on the server
(i.e., a local filesystem on the server) for quota tracking and enforcement
and the NFS client just gets the EDQUOT error the server got from the
filesystem. And for quota querrying (e.g. quota(1) command) there is a
special sideband rpc protocol handled by the quota tools. With NFSv4 there
is some support in the protocol itself for quota reporting but in Linux
this is not really supported because it does not map well to how Linux does
quotas.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

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