Re: Is there a "blackhole" /dev/null directory?

[Jan Engelhardt]

On Feb 14 2008 10:46, Andi Kleen wrote:
>Jasper Bryant-Greene <jasper@xxxxxxxxxxxx> writes:
>>
>> This could be done fairly trivially with FUSE, and IMHO is a good use
>> for FUSE because since you're just throwing most data away, performance
>> is not a concern.

There is a much more interesting 'problem' with a "/dev/null directory".

Q: Why would you need such a directory?
A: To temporarily fool a program into believing it wrote something.

Q: Should all files disappear? (e.g. "unlink after open")
A: Maybe not, programs may stat() the file right afterwards and
   get confused by the "inexistence".

Q: What if a program attempts to mkdir /dev/nullmnt/foo to just
   create a file /dev/nullmnt/foo/barfile?
A: /dev/nullmnt/foo must continue to exist or be accepted for a while,
   or perhaps for eternity.

Been there, done that, -
http://dev.computergmbh.de/wsvn/misc_kernel/nullfs/trunk/nullfs.c -
and hit that wall of unanswerable questions.
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