On Wed, Jan 17, 2007 at 01:04:22PM -0500, Shaya Potter wrote:
> Josef Sipek wrote:
> >On a more general level, what has higher priority a whiteout or a file?
>
> whiteout, if it's 'valid' (i.e. serves a purpose) to exist, as all my
> code does is skip whiteout searching if it doesn't matter if it exists.
If whiteout is the higher priority object, then readdir should not display
the file created under these circumstances. => pushing the "problem" to
readdir :)
> >I would like to find an alternative way to do whiteouts - not as separate
> >files. The only thing I can think of short of modifying the lower fs, is
> >using xattrs.
>
> would this work on NFS?
No :-/ It wouldn't also work on other fs that don't support xattr like vfat.
Another option (suggested by Ted Tso) which would fix persistent inode
numbers as well, is to create some minimal on-disk format and pass a file
containing this to mount.
This would give us:
1) persistent inode numbers
2) whiteouts that work on all filesystems
3) whiteouts not poluting the namespace (as it is the case with .wh. and
even the way BSD does things with modified lower filesystems)
Whiteouts should be associated with the union, not the branch (which we do
now). The current setup breaks things if you want to share the same branch
between several unions, or even stack unionfs on top of unionfs :)
Needless to say, implementing this would require quite a bit of effort and
planing.
Jeff.
--
Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are, by
definition, not smart enough to debug it.
- Brian W. Kernighan
_______________________________________________
unionfs mailing list
[email protected]
http://www.fsl.cs.sunysb.edu/mailman/listinfo/unionfs
