Florian Klink:
> But it seems to still load "loop" module as soon as I mount any branch
> with aufs.
Exactly.
> I'm not really into kernel code, but think this happens because
> test_overlap() from branch.c always calls au_test_loopback_overlap()
> when you add any branch, not only a when adding a "loopback branch".
> I there should be some check if it's really a loop branch, before
> loading everything (if that is possible).
Unfortunately, without loop module, it becomes impossible to check
whether the added branch is loopback mounted or not since linux-3.11.
> I tested again on a kernel with the same configuration, but without loop
> module file existing in /lib/modules/... (to simulate for example an
> initramfs that just wants to make a ro filesystem read-write by a tmpfs
> or similar and therefore has no loop module inside). I got the following
> error:
:::
> [ 69.996741] aufs au_test_loopback_overlap:39:mount[1519]:
> loop_backing_file() is not defined
> [ 69.996746] aufs test_add:279:mount[1519]: ../../images/arch-base is
> overlapped
In this case, the second message "... is overlapped" is meaningless.
I will stop it.
> So in my opinion, if it should be made possible to compile aufs with
> loop as a run-time-dependency, it should still work when it's not able
> to access the dependency.
I think I can understand what you mean.
But I don't agree. The case you mentioned above looks like a broken
system to me since the kernel is complied as BLK_DEV_LOOP=m but there is
no loop module. I don't think it a good idea to support such broken
system.
J. R. Okajima
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