Build fails on latest kernel (5.14.0-648)

[giuliocasella]

Building module on CentOS 9 stream fails with latest kernel available (5.14.0-648.el9.x86_64), due to a change in include file linux/timer.h: from_timer has been renamed to timer_container_of.

Changing from_timer to timer_container_of in vdo/dedupe.c fix this issue.

[lorelei-sakai]

Thank you for bringing this issue to our attention. We're working on fixing this, but due end-of-year scheduling we may not be able to put a fix out until next month. Thank you for your patience.

It sounds like you have managed to work around the issue for now?

[giuliocasella]

It sounds like you have managed to work around the issue for now?

Yes, I simply changed "from_timer" to "timer_container_of" on line 2968 of vdo/dedupe.c, and compilation works correctly. So I'm not stuck.
I didn't prepare a patch, because I think it should be worth something smarter (#ifdef stuff) to cover different kernel versions.

[giuliocasella]

dedupe.patch
Here's a trivial patch

[mtrojnar]

The latest fix breaks compatibility with older kernels.

Adding this may be a cleaner way to support the old and the new macro name:

#ifndef timer_container_of
#define timer_container_of from_timer
#endif

It's an out-of-tree module, so it should build against multiple kernel versions.

[giuliocasella]

The latest fix breaks compatibility with older kernels.

Adding this may be a cleaner way to support the old and the new macro name:

#ifndef timer_container_of
#define timer_container_of from_timer
#endif

It's an out-of-tree module, so it should build against multiple kernel versions.

+1 for this @mtrojnar patch

[lorelei-sakai]

Yes, we should have been more careful about handling older kernels. We'll look at patching this again soon.
In the meantime, you should be able to continue using the previous release (8.2.6.5) on older kernels.