Adam Chlipala <[EMAIL PROTECTED]> writes:
> Adam Megacz wrote:
>> The second kind (clone) is basically a "copy-on-write" snapshot of a
>> read/write volume.

> Oh, cool.  I was wondering whether we could achieve some of the 
> backing-up benefits of hard links without being able to use them.

Yes; in fact, clones go far beyond hard links since they COW on a
block-by-block basis rather than file-by-file.

Also, there's a reason why AFS only supports hard links within a
single directory: unlike traditional UNIX semantics, AFS can query an
inode for its parent directory.  This operation is ill-defined if the
filesystem allows hardlinking a single inode into multiple
directories.

AFS needs to be able to do this reverse lookup because access to a
file is determined by the ACL on its parent directory, not
(exclusively) on the mode bits of the file itself.

  - a

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