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Message-ID: <20100304200700.GA6092@atrey.karlin.mff.cuni.cz>
Date: Thu, 4 Mar 2010 21:07:00 +0100
From: Jan Kara <jack@...e.cz>
To: Dmitry Monakhov <dmonakhov@...nvz.org>
Cc: linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 4/5] ext4: add isolated project support
Hi,
> PROJECT_ISOLATION
> This feature allows to create an isolated project subtrees.
> Isolation means what:
> 1) directory subtree has no common inodes (no hadlinks across subtrees)
> 2) All descendants belongs to the same subtree.
>
> Project subtree's isolation assumptions:
> 1)Inode can not belongs to different subtree trees
> Otherwise changes in one subtree result in changes in other subtree
> which contradict to isolation criteria.
Just a curious question:
Do you really need this subtree separation in your envisioned containers
usecase? Because there I imagine you have one project_id per container,
containers form disjoint subtrees (at least their writeable parts) and
each file & directory has this project_id set and you forbid to manipulate
project id's from inside the container (otherwise you'd have problems with
enforcing quota limits I guess).
And when project_id is a per-inode property, quota has no problems with it
(is well defined) even without subtree separation. So is this subtree
separation really needed?
Honza
--
Jan Kara <jack@...e.cz>
SuSE CR Labs
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