RFC: unionfs multiple mounts, cross mounts and recursive
mounts limits and manegement feature
aavzz at yandex.ru
Thu Apr 21 07:20:12 UTC 2011
On Thu, 2011-04-21 at 14:49 +0900, Daichi GOTO wrote:
> It is adjustable with sysctl value 'vfs.unionfs.recursive_limit' as
> multiple mounts limits. The default value is 1 and it means two-layered ok.
> Max value of 'vfs.unionfs.recursive_limit' is 8, it is heuristic value.
> I couldn't get a system panic unless 'vfs.unionfs.recursive_limit' is over 8.
Hmm, 8 is not enough for me, i need more :)
On the other hand, why do we need recursion in unionfs_statfs
at all? IMHO recursion in kernel is evil because it has a potencial
of resource exhaustion.
This recursion in unionfs_statfs is used to gather statistic (some of
which is faked according to comments in the procedure)
why not replace recursion with cycle? (I'm not skilled enough do do
and a feature request:
it would be great if it was possible to umount one of multiple unionfs:
mount -t unionfs /var/ftpdata1 /var/ftp
mount -t unionfs /var/ftpdata2 /var/ftp
how to unmount /var/ftpdata1 only?
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