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

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Message-Id: <1202981957.10928.17.camel@phobos.jasper.bg>
Date:	Thu, 14 Feb 2008 22:39:17 +1300
From:	Jasper Bryant-Greene <jasper@...x.geek.nz>
To:	rzryyvzy <rzryyvzy@...shmail.net>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Is there a "blackhole" /dev/null directory?

On Thu, 2008-02-14 at 10:30 +0100, rzryyvzy wrote:
> /dev/null is often very useful, specially if programs force to save data in some file. But some programs like to creates different temporary file names, so /dev/null could no more work.
> 
> What is with a "/dev/null"-directory?
> I mean a "blackhole pseudo directory" which eats every write to null.
> 
> Here is how it could work:
> mount -t nulldir nulldir /dev/nulldir
> 
> Now if a program does a create(2),
> it creates in the memory the file with its fd.
> Then if a program does a write(2) to the fd, it eats the writes and give out fakely it has written the number of bytes.
> When the program calls does a close(2) of the fd, then the complete inode is deleted in the memory.
> 
> The directory should  be permanently empty except for the inodes with open file descriptors. So only inode information would be temporary saved in this "nulldir tmpfs" directory.
> 
> Is there already existing a possibility to create a null directory?

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.

-j

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