Re: [RFC] shmgetfd idea

[John Stultz <john.stultz@linaro.org>]

On 01/27/2014 07:52 PM, H. Peter Anvin wrote:
> On 01/27/2014 05:37 PM, John Stultz wrote:
>> In the Android case, its important to have this interface to atomically
>> provide these unlinked tmpfs fds, because they'd like to avoid having
>> tmpfs mounts that are writable by applications (since that creates a
>> potential DOS on the system by applications writing random files that
>> persist after the process has been killed). It also provides better
>> life-cycle management for resources, since as the fds never have named
>> links in the filesystem, their resources are automatically cleaned up
>> when the last process with the fd dies, and there's no potential races
>> between create and unlink with processes being terminated, which avoids
>> the need for cleanup management.
>>
> What about if tmpfs could be restricted to only only O_TMPFILE open()s?
>  This pretty much amounts to an option to prevent tmpfs from creating
> new directory entries.

Thanks for reminding me about O_TMPFILE.. I have it on my list to look
into how it could be used.

As for the O_TMPFILE only tmpfs option, it seems maybe a little clunky
to me, but possible. If others think this would be preferred over a new
syscall, I'll dig in deeper.

thanks
-john

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