Re: [PATCH] cowlinks v2

[Eric W. Biederman]

Jamie Lokier <jamie@xxxxxxxxxxxxx> writes:

> Here's a tricky situation:
> 
>    1. A file is cowlinked.  Then each cowlink is mmap()'d, one per process.
> 
>    2. At this point both mappings share the same pages in RAM.

Why they have different inodes?  
 
>    3. Then one of the cowlinks is written to...

I would not worry about sharing page cache entries unless this becomes
a common case.  If you want to avoid the hit of rereading the file when
you have a cow copy it should be simple enough to walk through the list
of cow copies and see if anyone else has it open.

Eric
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