On Wed, 29 Jul 2009, Andriy Gapon wrote:
"Subdirectory is automatically a new filesystem" property - an administrator
turns
on this magic property of a filesystem, after that every mkdir *in the root* of
that filesystem creates a new filesystem. The new filesystems have
default/inherited properties except for the magic property which is off.
Right now I see this as being mostly useful for /home. Main benefit in this case
is that various user administration tools can work unmodified and do the right
thing when an administrator wants a policy of a separate fs per user
But I am sure that there could be other interesting uses for this.
It's a nice idea, but zfs filesystems consume memory and have overhead.
This would make it trivial for a non-root user (assuming they have
permissions) to crush the host under the weight of .. mkdir.
$ mkdir -p waste/resources/now/waste/resources/now/waste/resources/now
(now make that much longer and put it in a loop)
Also, will rmdir call zfs destroy? Snapshots interacting with that could
be somewhat unpredictable. What about rm -rf?
It'd either require major surgery to userland tools, including every
single program that might want to create a directory, or major surgery to
the kernel. The former is unworkable, the latter .. scary.
--
Andre van Eyssen.
mail: an...@purplecow.org jabber: an...@interact.purplecow.org
purplecow.org: UNIX for the masses http://www2.purplecow.org
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