Re: 2.6.11-rc1-mm1

[Christoph Hellwig]

On Sun, Jan 16, 2005 at 01:05:19PM -0600, Tom Zanussi wrote:
> One of the things that uses these functions to read from a channel
> from within the kernel is the relayfs code that implements read(2), so
> taking them away means you wouldn't be able to use read() on a relayfs
> file.

Removing them from the public API is different from disallowing the
read operation.

> That wouldn't matter for ltt since it mmaps the file, but there
> are existing users of relayfs that do use relayfs this way.  In fact,
> most of the bug reports I've gotten are from people using it in this
> mode.  That doesn't mean though that it's necessarily the right thing
> for relayfs or these users to be doing if they have suitable
> alternatives for passing lower-volume messages in this way.  As others
> have mentioned, that seems to be the major question - should relayfs
> concentrate on being solely a high-speed data relay mechanism or
> should it try to be more, as it currently is implemented?

I'd say let it do one thing well, that is high-volume data transfer.

> If the
> former, then I wonder if you need a filesystem at all - all you have
> is a collection of mmappable buffers and the only thing the filesystem
> provides is the namespace.  Removing read()/write() and filesystem
> support would of course greatly simplify the code; I'd like to hear
> from any existing users though and see what they'd be missing.

What else would manage the namespace?

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