Re: PUFFS putpages/read race?

[Thor Lancelot Simon <tls%panix.com@localhost>]

On Fri, Jul 20, 2012 at 05:16:05AM +0200, Emmanuel Dreyfus wrote:
> Thor Lancelot Simon <tls%panix.com@localhost> wrote:
> 
> > If, nonetheless, the user processs returns inconsistent data for a
> > subsequent read, that is a bug.  In the user process, I would say.
> > The user process *must* preserve ordering of reads and writes to the
> > same underlying resource.
> 
> But the filesystem may rely of vnode locking: VOP_READ and VOP_WRITE are
> supposed to operate on locked vnodes. If the kernel starts an operation
> and releases the lock before completion, can we blame the filesystem for
> breaking?

If the filesystem receives a write, then a read, and reorders the read
around the write, I think that's *always* a bug.

> -- 
> Emmanuel Dreyfus
> http://hcpnet.free.fr/pubz
> manu%netbsd.org@localhost

-- 
 Thor Lancelot Simon                                          
tls%panix.com@localhost
   But as he knew no bad language, he had called him all the names of common
 objects that he could think of, and had screamed: "You lamp!  You towel!  You
 plate!" and so on.              --Sigmund Freud