[arch-dev-public] kernel26 unionfs/aufs conflict

Simo Leone simo at archlinux.org
Wed Mar 26 03:27:13 EDT 2008

Hey guys,

The unionfs patch in our kernel right now is old, and suffers from a few
pretty bad bugs that cause frequent kernel panics.
Anyhow, there's a new version at
which works fine. However, it looks like it directly conflicts with the
splice patch needed for aufs.
Both unionfs and the aufs patch export a couple functions for modules to
use in splice.c, and they happen to export them as different function
names, hence the conflict. I'd argue that the unionfs patch does it
"more correctly" given that it prefixes the function names with
vfs_, where the aufs patch simply exports them as-is (there goes the
namespace. ick.).

Now, we can work around this with a dirty little hack that just exports
both names, and has one simply call/return the other.
Another alternative is to let unionfs do it their way, and patch our
out-of-tree aufs module accordingly, which isn't a whole lot cleaner.
The last option is to drop either aufs or unionfs, which isn't exactly
desirable either... although they do provide similar functionality.

Anyhow, I need some opinions here, and it's ultimately up to the kernel
maintainers. I'm willing to write patches for options 1 or 2 if that's
how you want to do it.

As an aside, I'm going to read up on it and figure out who really does
it the "right" way and let the other project know about it.

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