Date: Fri, 24 Jun 2011 12:30:16 +0200 From: Peter Holm <peter@holm.cc> To: Kostik Belousov <kostikbel@gmail.com> Cc: freebsd-current@freebsd.org Subject: Re: Thoughts on TMPFS no longer being considered "highly experimental" Message-ID: <20110624103016.GA71991@x2.osted.lan> In-Reply-To: <20110623202153.GS48734@deviant.kiev.zoral.com.ua> References: <20110623163109.GA508@dragon.NUXI.org> <20110623202153.GS48734@deviant.kiev.zoral.com.ua>
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On Thu, Jun 23, 2011 at 11:21:53PM +0300, Kostik Belousov wrote:
> On Thu, Jun 23, 2011 at 09:31:09AM -0700, David O'Brien wrote:
> > Does anyone object to this patch?
> >
> > David Wolfskill and I have run TMPFS on a number of machines for two
> > years with no problems.
> >
> > I may have missed something, but I'm not aware of any serious PRs on
> > TMPFS either.
> >
> >
> > Index: tmpfs_vfsops.c
> > ===================================================================
> > --- tmpfs_vfsops.c (revision 221113)
> > +++ tmpfs_vfsops.c (working copy)
> > @@ -155,9 +155,6 @@ tmpfs_mount(struct mount *mp)
> > return EOPNOTSUPP;
> > }
> >
> > - printf("WARNING: TMPFS is considered to be a highly experimental "
> > - "feature in FreeBSD.\n");
> > -
> > vn_lock(mp->mnt_vnodecovered, LK_SHARED | LK_RETRY);
> > error = VOP_GETATTR(mp->mnt_vnodecovered, &va, mp->mnt_cred);
> > VOP_UNLOCK(mp->mnt_vnodecovered, 0);
>
> The things I am aware of:
> - there is a races on the lookup. They were papered over in r212305,
> but the bug was not really fixed, AFAIR.
>
> - the tmpfs does double-buffering for the mapped vnodes. This is quite
> insulting for the memory-backed fs, isn't it ? I have a patch, but it is
> still under review.
>
> - I believe Peter Holm has more test cases that fails with tmpfs. He
> would have more details. I somewhat remember some panic on execve(2) the
> binary located on tmpfs.
>
I ran the TMPFS tests I have and so far I only spotted the mmap(2)
problem:
http://people.freebsd.org/~pho/stress/log/tmpfs/
> Removing the warning will not make the issues coming away.
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--
Peter
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