tree 8b8daca4fb5153211289b98b012dc648aacff2d3
parent e4d7d6f4d36daff6aad84f96e48debde8e6ed09e
author Lars Ellenberg <lars@linbit.com> 1398703409 +0200
committer Jens Axboe <axboe@fb.com> 1398887215 -0600

drbd: always implicitly close last epoch when idle

Once our sender thread needs to wait_for_work(),
and actually needs to schedule(), just before we do that,
we already check if it is useful to implicitly close the last epoch.

The condition was too strict: only implicitly close the epoch,
if there have been no new (write) requests at all.

The assumption was that if there were new requests, they would
always be communicated one way or another, and would send necessary
epoch separating barriers explicitly.

This is not always true, e.g. when becoming diskless,
or while explicitly starting a full resync.

The last communicated epoch could stay open for a long time,
locking down corresponding activity log extents.

It is safe to always implicitly send that last barrier, as soon as we
determin that there cannot be more requests in the last communicated
epoch, even if there have been (uncommunicated) new requests in new
epochs meanwhile.

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