[PATCH v3 6/6] locks: add new "private" lock type that is owned by the filp

[Christoph Hellwig]

On Tue, Dec 17, 2013 at 08:31:25AM -0500, Jeff Layton wrote:
> So, I think the above semantics are pretty clear, but now that I've had
> a go at sitting down to document this stuff for the POSIX spec and
> manpages, it's clear how convoluted the text in there is becoming.
> 
> That makes me wonder...would we be better off with a new set of cmd
> values here instead of new l_type values? IOW, we could add new:
> 
> F_GETLKP
> F_SETLKP
> F_SETLKPW

That seems a tad cleaner to me indeed.

> ...and then just reuse the same F_RDLCK/F_WRLCK/F_UNLCK values? With
> that too, we could create a new equivalent to struct flock that has
> fixed length types instead of dealing with the off_t mess.

For the Posix interface you'd need an off_t as that's what the whole
API uses for file offsets.  We could make sure to always use a off64_t
for the kernel interface though.

What is the API you propose to posix?  An new posix_lockf?