Re: [PATCH 04/23] vfs: Introduce infrastructure for revoking a file

[Nick Piggin]

On Tue, Jun 02, 2009 at 03:56:02PM -0700, Eric W. Biederman wrote:
> Nick Piggin <npiggin@xxxxxxx> writes:
> 
> >> In addition for a complete solution we need:
> >> - A reliable way the file structures that we need to revoke.
> >> - To wait for but not tamper with ongoing file creation and cleanup.
> >> - A guarantee that all with user space controlled duration are removed.
> >> 
> >> The file_hotplug_lock has a very unique implementation necessitated by
> >> the need to have no performance impact on existing code.  Classic locking
> >
> > Well, it isn't no performance impact. Function calls, branches, icache
> > and dcache...
> 
> Practically none.

OK that's different from none. There is obviously overhead.

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