Re: [V9fs-developer] Make mmap read-write?

[Rob L. <ro...@la...>]

On 05/17/2013 03:36:46 AM, Dominique Martinet wrote:
> Hi,
> 
> Dominique Martinet wrote on Wed, Mar 20, 2013 :
> > I've seen that mmap in 9p has been made read-only in the client for
> > quite a while (commit 14b8869ff in feb 2008), and the commit message
> > says it was because this would eventually cause a kernel BUG() call.
> >
> > I've also seen some threads in mail archives concerning writable
> > mmap and cache here:
> >  http://thread.gmane.org/gmane.linux.kernel/1096376
> > and later
> >  http://www.spinics.net/lists/linux-fsdevel/msg42311.html
> >
> > And the code (fs/9p/vfs_file.c) looks like to me writable mmap is
> > available only for cache=fscache or loose.
> >
> >
> > So question:
> > Would a writable mmap be possible in 9p without cache altogether,  
> or are
> > they incompatible at a theorical/protocol level?
> 
> 
> Allowing myself to repost this (with the revert commit author in  
> direct
> copy) as it didn't get any reply.

I'm interested in seeing this work.

Has anybody tried any of the filesystem stress tests on this? The  
leader seems to be "xfstests":

   http://xfs.org/index.php/Getting_the_latest_source_code#XFS_tests

But there's a bunch of others:

   http://dbench.samba.org/
   https://lwn.net/Articles/326926/
   http://www.bullopensource.org/ext4/ext4_test_plan.html

And so on. That might be better than just enabling it and hoping it  
works. Instead actually trying to make it fail under load...

Rob