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Message-ID: <4FC769C9.3040300@oracle.com>
Date: Thu, 31 May 2012 20:53:29 +0800
From: Jeff Liu <jeff.liu@...cle.com>
To: Glauber Costa <glommer@...allels.com>
CC: containers@...ts.linux-foundation.org, cgroups@...r.kernel.org,
jack@...e.cz, daniel.lezcano@...e.fr, tytso@....edu, bpm@....com,
chris.mason@...cle.com, hch@...radead.org,
christopher.jones@...cle.com, david@...morbit.com,
tinguely@....com, tm@....ma, linux-ext4@...r.kernel.org,
linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 04/12] container quota: introduce container disk quota
data header file.
On 05/31/2012 05:10 PM, Glauber Costa wrote:
>> +
>> +/* Operations for quota control */
>> +struct ns_quotactl_ops {
>> + int (*quota_on)(struct mnt_namespace *, int);
>> + int (*quota_off)(struct mnt_namespace *, int);
>> + int (*get_info)(struct mnt_namespace *, int, struct if_dqinfo *);
>> + int (*set_info)(struct mnt_namespace *, int, struct if_dqinfo *);
>> + int (*get_dqblk)(struct mnt_namespace *, int, qid_t,
>> + struct fs_disk_quota *);
>> + int (*set_dqblk)(struct mnt_namespace *, int, qid_t,
>> + struct fs_disk_quota *);
>> +};
>> +
>
> That is quite bad. Just have the same signature. Which namespace you
> belong to can *always* be derived from the calling process, you should
> never need to specify that in any interface. It is of course fine to do
> that in functions internal to the kernel, but not this.
Exactly, "struct mnt_namespace" should not be presented at any quota
operation interface, retrieve it through current->nsproxy->mnt_ns should
be fine.
> You should rethink the whole ns_quota thing. Some of it I believe will
> have to stay, I doubt we'll be able to be completely transparent. But
> the core of your changes have to be making sure a hierarchical walk over
> the valid quotas work well, finding out what are those valid quotas, etc.
> The interface should be kept as unchanged as possible, and this can be
> achieved by things like automatic discover of the current namespace, and
> pre-operational container setup for the relevant files.
Thanks for teaching me that, let me try to refactor ns_quota to make
the change as little as possible.
-Jeff
>
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