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A brief history of union mountsA brief history of union mountsPosted Jul 23, 2010 20:01 UTC (Fri) by vaurora (guest, #38407)In reply to: A brief history of union mounts by neilbrown Parent article: A brief history of union mounts
Excellent idea - you've just described fallthru dentries. :)
The implementation of fallthrus is pretty small, around a hundred lines in main VFS and then you reuse the whiteout infrastructure in the client file systems.
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A brief history of union mounts Posted Jul 24, 2010 2:10 UTC (Sat) by neilbrown (subscriber, #359) [Link]
> Excellent idea - you've just described fallthru dentries. :)
Yes.... after writing that I went back through the original article, noticed 'fallthru' this time, and felt a bit sheepish.
I don't quite see either how you would implement fallthru using whiteout though, or why you would still want whiteout if you were using copy-up + fallthru..
It is a pity that a block-based COW solution is so inefficent - it is such a simple solution that would address many of the use-cases (not the NFS-as-underlying-filesystem case of course).
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