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Date: Thu, 22 Aug 2013 19:20:21 -0400
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Subject: Re: Allowing tmpfs to be mounted in jail?
From: "Sam Fourman Jr." <sfourman@gmail.com>
To: Dewayne Geraghty <dewayne.geraghty@heuristicsystems.com.au>
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Cc: FreeBSD FS <freebsd-fs@freebsd.org>, freebsd-security@freebsd.org,
 Xin LI <d@delphij.net>
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Xin Li,

>
> I can envision the use of tmpfs without providing access to mounting other
> devices within a jail context.
>
> It would be better if this feature had its own sysctl to control the
> jail's state, particularly as a DOS could "inadvertently" be
> introduced, per Kib's earlier point. Other devices-types have additional
> mitigation strategies, such as exclusion via dev.rules
> which tmpfs doesn't have.
>
> Regards, Dewayne.
>
>
 Xin,

This is a Great feature and it has several use cases, what about the
possibility of a sysctl that adds a max amount
that a jail could set a tmpfs... this would be per jail, now in theory you
could over commit resources, but that would
be a administrators decision, and not one jail could consume all resources.
-- 

Sam Fourman Jr.