tree 475048ee4f70f46a9a2b01f9350752b72d16ae6a
parent a3025a273700fc51dd561c7b2941f3c9db9be90a
author Philipp Reisner <philipp.reisner@linbit.com> 1346764580 +0200
committer Philipp Reisner <philipp.reisner@linbit.com> 1352466699 +0100

drbd: panic on delayed completion of aborted requests

"aborting" requests, or force-detaching the disk, is intended for
completely blocked/hung local backing devices which do no longer
complete requests at all, not even do error completions.  In this
situation, usually a hard-reset and failover is the only way out.

By "aborting", basically faking a local error-completion,
we allow for a more graceful swichover by cleanly migrating services.
Still the affected node has to be rebooted "soon".

By completing these requests, we allow the upper layers to re-use
the associated data pages.

If later the local backing device "recovers", and now DMAs some data
from disk into the original request pages, in the best case it will
just put random data into unused pages; but typically it will corrupt
meanwhile completely unrelated data, causing all sorts of damage.

Which means delayed successful completion,
especially for READ requests,
is a reason to panic().

We assume that a delayed *error* completion is OK,
though we still will complain noisily about it.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>