Re: [fuse-devel] [PATCH] FUSE/CUSE: implement direct mmap support

From: Miklos Szeredi
Date: Thu Feb 11 2010 - 07:25:25 EST


On Thu, 11 Feb 2010, Tejun Heo wrote:
> > And there's a weakness in the current server side mmap interface, for
> > example:
> >
> > 1) user mmaps region 3-5 (in page index)
> > server maps this region at 3-5
> >
> > 2) user mmaps region 1-7
> > server can't tell kernel that it wants to reuse region 3-5 but
> > wants to create two other regions
> >
> > What happens in that case?
>
> If the server wants the two regions to be separate, it can map it to
> say 5-11 and returnt he offset of 5. If it wants them to be shared,
> it will have to mmap 1-2 and 6-7 and return offset of 1.

What if region 6-7 is already occupied (e.g. because a separate region
was put there)?

Thanks,
Miklos
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