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List:       fuse-devel
Subject:    Re: [fuse-devel] fuse low level cache
From:       Nikolaus Rath <Nikolaus () rath ! org>
Date:       2009-08-31 15:02:42
Message-ID: 873a78m3fx.fsf () latitude ! rath ! org
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Miklos Szeredi <miklos@szeredi.hu> writes:
> One way to solve this would be to go with the "high level lib"
> approach of always checking the full path up to the root in the
> filesystem.  This has problems with hard links, because the path
> leading up to the inode is not unique.

The problem is only with *directory* hard links, isn't it? But are they
really used in practice? My impression is that they are a potential
source of trouble in so many cases that whatever advantage they may
offer is just not worth it.  

> Another way would be to move ACL checking into the kernel.  But that
> introduces another problem: needing to cache extended attributes for
> better performance.
>
> Another approach would be to cache permissions per-user or more
> precisely per fsgid/fsuid pair for each inode.  This is perhaps the
> most correct solution, but would probably require quite a bit of work
> to implement...

I agree with that though, no matter if directory hard links are common
or not, caching permissions or xattrs is the better(tm) solution.

Best,

   -Nikolaus

-- 
  »Time flies like an arrow, fruit flies like a Banana. «

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