Messages in this thread | | | Subject | Re: [fuse-devel] [PATCH] FUSE/CUSE: implement direct mmap support | From | Miklos Szeredi <> | Date | Wed, 10 Feb 2010 13:15:28 +0100 |
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On Wed, 10 Feb 2010, Tejun Heo wrote: > > Okay, lets be a little clearer. There are client side maps and server > > side maps. Client side maps are naturally aligned (same offset -> > > same page). > > Same offset -> same page doesn't hold.
Right, I really meant same page -> same offset. If the same offset is mapped to multiple pages: no problem. If the same page is mapped to multiple offsets, then obviously it's not going to work properly.
> Can you please elaborate how you think the thing can work without > referencing the proposed implementation? Let's find out where the > misundertanding is.
Thinking about it I'm not really sure...
Maybe the problem is that the propsed solution allows too much freedom. Normally there's a 1:1 relationship between pages and offsets. But we want to break that for CUSE, because two different mappings of a char dev might point to completely different pages, right?
When does that happen? Can it happen that two mappings of the same file descriptor will have different backing pages?
Thanks, Miklos
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