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The two sides of reflink()The two sides of reflink()Posted May 6, 2009 8:52 UTC (Wed) by lmb (subscriber, #39048)In reply to: The two sides of reflink() by amw Parent article: The two sides of reflink()
The answer to the quota question points out that this call is only the first step.
There is, of course, also a need for reflinkstat() or whatever it is going to be called - one needs to find out how many blocks are part of a specific COW, and also reflinkdiff(), which enumerates the (meta-)data blocks which differ from the link target (needed for efficient rsync/backup).
Then, it also becomes possible to use quota to account just the difference, i.e. the actual space used by the reflink.
A further complication arises when we look at using reflink() on directories, which would of course also be quite desirable (for snapshots, multi-use chroots etc). That will be an interesting direction to explore ;-)
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The two sides of reflink() Posted May 9, 2009 23:52 UTC (Sat) by butlerm (subscriber, #13312) [Link]
ZFS (for example) uses an COW design where it isn't remotely practical to
figure out which files / snapshots share which blocks in a reasonable amount of time. I imagine BTRFS is similar.
However both aforementioned filesystems store block checksums, so perhaps a
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