Re: [PATCH 1/4] inotify: Add infrastructure to account inotify limits per-namespace

[Nikolay Borisov <kernel@kyup.com>]

On 06/06/2016 11:05 AM, Cyrill Gorcunov wrote:
> On Wed, Jun 01, 2016 at 10:52:57AM +0300, Nikolay Borisov wrote:
>> This patch adds the necessary members to user_struct. The idea behind
>> the solution is really simple - user the userns pointers as keys into
>> a hash table which holds the inotify instances/watches counts. This
>> allows to account the limits per userns rather than per real user,
>> which makes certain scenarios such as a single mapped user in a
>> container deplete the inotify resources for all other users, which
>> map to the exact same real user.
>>
>> Signed-off-by: Nikolay Borisov <kernel@kyup.com>
> ...
>> +static inline unsigned long inotify_dec_return_dev(struct user_struct *user,
>> +						   void *key)
>> +{
>> +	struct inotify_state *state;
>> +	unsigned long ret;
>> +
>> +	spin_lock(&user->inotify_lock);
>> +	state = __find_inotify_state(user, key);
>> +	ret = --state->inotify_devs;
>> +	spin_unlock(&user->inotify_lock);
>> +
>> +	return ret;
>> +}
> 
> Hi Nikolay! Could you please explain why this new function is not used anywhere
> in other patches or I miss something obvious?

Hi Cyrill,

It seems this is a left-over from an earlier, internal version of this
patchset. You can disregard it. Also, given the direction that the
discussion with Eric took I think I will be redesigning the solution
entirely. Thanks for taking the time to read the code!


Nikolay