Zach Brown 784cda9bee scoutfs: more carefully set lock bast mode ...

Locks get a bast call from the dlm when a remote node is blocked waiting
for the mode of a lock to change.  We'd set the mode that we need to
convert to and kick off lock work to make forward progress.

The bast calls can happen at any old time.  If a call came in as we were
unlocking a lock we'd set its bast mode even though it was being
unlocked and would not need to be down converted.

Usually this bad mode would be fine because the lock was idle and would
just be freed after being locked.

But if someone was actively waiting for the lock it would get stuck in
an unlocked state.  The bad bast mode would prevent it from being
upconverted, but the waiters would stop it from being freed.

We fix this by only setting the mode from the bast call if there is
really work to do.  This avoids setting the bast for unlocked locks
which will let the lock state machine re-acquire them and make forward
progress on behalf of the waiters.

Signed-off-by: Zach Brown <zab@versity.com>

2018-07-02 14:16:50 -07:00

kmod

scoutfs: more carefully set lock bast mode

2018-07-02 14:16:50 -07:00

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