Re: [fuse-devel] delta filesystem prototype

[hooanon05@yahoo.co.jp]

Dave Kleikamp:
> On Wed, 2009-03-04 at 12:52 +0100, Goswin von Brederlow wrote:
	:::
> > By the way. If you mmap a file in fuse shared twice wouldn't the
> > kernel share the physical pages. So the first access calls fuse and
> > loads the data into memory, the second access would just get the same
> > physical page mapped. Right?
> 
> Right.  Some of my comments were a result of not being clear on what J.
> R. meant when he asked about the first mapping being to the lower file.
> Both mmaps to the same file in fuse would access the same physical
> pages.

I didn't know how fuse implements mmap and sharing pages. Additionally
there is no mmap code in deltafs.c. So I wrote "it is unclear how do you
implment mmap".

Now I am reading fuse (instead of deltafs.c) and begin understanding
that fuse and deltafs work as you expected. But the implementation seems
different a little to me.
These two mappings are not sharing memory pages but keeping the latest
contents by re-reading, do they?


J. R. Okajima