ksmbd: invalidate durable handles on oplock break

ksmbd: invalidate durable handles on oplock break

When a durable handle is preserved after a disconnect, its oplock state
can still block later opens. If another client opens the same file and
the preserved oplock or lease has to be broken, the old durable handle
must no longer be reconnectable after the break cannot be acknowledged.

ksmbd was treating a missing connection, or an oplock break timeout, as a
successful break only by downgrading the oplock state.  The old durable
handle remained reconnectable, so a later durable reconnect for that
stale handle could succeed.

The open path can also see a detached durable handle before the break
notification helpers fully dispose of it. Invalidate such a preserved
durable handle directly when a competing open has to break its batch or
exclusive oplock, while leaving ordinary durable reconnects without a
competing open untouched.

If the old handle still reaches the reconnect path, reject it when the
same inode already has another active open. This matches the
smb2.durable-open.open2-lease/open2-oplock sequence where a later open
replaces the disconnected durable owner and the stale first handle must
not be reclaimed.

Also, reconnect lookup used only the persistent id. A new durable open
can get a persistent id that matches the stale reconnect request after
the old durable state is invalidated. Preserve the disconnected
handle's old volatile id and require durable reconnect contexts to match
it, so a stale reconnect cannot attach to a different durable open.

Windows allows the later open to proceed and rejects the old reconnect
with STATUS_OBJECT_NAME_NOT_FOUND. The smbtorture
smb2.durable-open.oplock test covers this case.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>