Re: [RFC] shmem: Add eventfd notification on utlilization level

[Lukáš Czerner]

On Tue, 10 Mar 2015, Beata Michalska wrote:

> Date: Tue, 10 Mar 2015 16:25:12 +0100
> From: Beata Michalska <b.k.m.devel@xxxxxxxxx>
> To: Jan Kara <jack@xxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>,
>     Kyungmin Park <kmpark@xxxxxxxxxxxxx>,
>     Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>,
>     Hugh Dickins <hughd@xxxxxxxxxx>, linux-mm <linux-mm@xxxxxxxxx>,
>     Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>,
>     Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>,
>     Linux Filesystem Mailing List <linux-fsdevel@xxxxxxxxxxxxxxx>,
>     Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>,
>     Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> Subject: Re: [RFC] shmem: Add eventfd notification on utlilization level
> 
> On 03/10/2015 03:22 PM, Jan Kara wrote:
> > On Tue 10-03-15 06:03:23, Christoph Hellwig wrote:
> >> On Tue, Mar 10, 2015 at 10:51:41AM +0900, Kyungmin Park wrote:
> >>> Any updates?
> >> Please just add disk quota support to tmpfs so thast the standard quota
> >> netlink notifications can be used.
> >   If I understand the problem at hand, they are really interested in
> > notification when running out of free space. Using quota for that doesn't
> > seem ideal since that tracks used space per user, not free space on fs as a
> > whole.
> >
> > But if I remember right there were discussions about ENOSPC notification
> > from filesystem for thin provisioning usecases. It would be good to make
> > this consistent with those but I'm not sure if it went anywhere.
> >
> > 								Honza
> 
> The ideal case here, would be to get the notification, despite the type
> of the actual filesystem, whenever the amount of free space drops below
> a certain level. Quota doesn't seem to be the right approach here.
> 
> BR
> Beata Michalska

A while back I was prototyping a netlink notification interface for
file systems, but it went nowhere.

https://lkml.org/lkml/2011/8/18/170

So maybe it's time get back to the drawing board and finish the
idea, since it seems to be some interest in this now.

-Lukas

> 
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