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Re: [PATCH 02/12] quota: Allow each filesystem to specify which quota ty

To: Christoph Hellwig <hch@xxxxxx>
Subject: Re: [PATCH 02/12] quota: Allow each filesystem to specify which quota types it supports
From: Jan Kara <jack@xxxxxxx>
Date: Wed, 22 Oct 2014 18:51:50 +0200
Cc: Jan Kara <jack@xxxxxxx>, linux-fsdevel@xxxxxxxxxxxxxxx, linux-ext4@xxxxxxxxxxxxxxx, Dave Chinner <david@xxxxxxxxxxxxx>, xfs@xxxxxxxxxxx, cluster-devel@xxxxxxxxxx, Steven Whitehouse <swhiteho@xxxxxxxxxx>, Mark Fasheh <mfasheh@xxxxxxxx>, Joel Becker <jlbec@xxxxxxxxxxxx>, ocfs2-devel@xxxxxxxxxxxxxx, reiserfs-devel@xxxxxxxxxxxxxxx, Jeff Mahoney <jeffm@xxxxxxx>, Dave Kleikamp <shaggy@xxxxxxxxxx>, jfs-discussion@xxxxxxxxxxxxxxxxxxxxx, tytso@xxxxxxx, viro@xxxxxxxxxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20141022162915.GB18443@xxxxxx>
References: <1413902316-17997-1-git-send-email-jack@xxxxxxx> <1413902316-17997-3-git-send-email-jack@xxxxxxx> <20141022162915.GB18443@xxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Wed 22-10-14 18:29:15, Christoph Hellwig wrote:
> On Tue, Oct 21, 2014 at 04:38:26PM +0200, Jan Kara wrote:
> > Currently all filesystems supporting VFS quota support user and group
> > quotas. With introduction of project quotas this is going to change so
> > make sure filesystem isn't called for quota type it doesn't support by
> > introduction of a bitmask determining which quota types each filesystem
> > supports.
> 
> Why don't you keep this bitmask in the dquot.c instead of pushing it
> to the caller?  So far usage of s_dquot is mostly confined to dquot.c
> (with a few leaks to the filesystems using it), so keeping it that
> way seems like a good idea.
  So there are two reasons:
1) Currently if you call quotactl() with invalid quota type you'll get
EINVAL. To maintain this with addition of project quotas you need to check
the types early before calling check_quotactl_permission() and other
checks.

2) I didn't want filesystem quotactl callbacks to deal with quota types
they don't support. Sure each fs could do a type check in the callback but
this looked easier.

Now I see your point about s_dquot and I can move allowed_types out of
s_dquot if that makes you happier. But otherwise what I did still seems as
the best solution to me.

                                                                Honza
-- 
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR

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