Re: O_DIRECT question

[Helge Hafting]

Michael Tokarev wrote:
> Chris Mason wrote:
> []
>   
> > I recently spent some time trying to integrate O_DIRECT locking with
> > page cache locking.  The basic theory is that instead of using
> > semaphores for solving O_DIRECT vs buffered races, you put something
> > into the radix tree (I call it a placeholder) to keep the page cache
> > users out, and lock any existing pages that are present.
> >     
>
> But seriously - what about just disallowing non-O_DIRECT opens together
> with O_DIRECT ones ?
>   
Please do not create a new local DOS attack.
I open some important file, say /etc/resolv.conf
with O_DIRECT and just sit on the open handle.
Now nobody else can open that file because
it is "busy" with O_DIRECT ?

Helge Hafting
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