commit 4a23f2649698272abcd9e0c9a992d65739f32792
author Philipp Reisner <philipp.reisner@linbit.com> Tue Jan 11 17:42:17 2011 +0100
committer Philipp Reisner <philipp.reisner@linbit.com> Thu Mar 10 11:45:32 2011 +0100
tree 3921ce5019d9d72befc48dbf14850c189bce5543
parent 2b8a90b55533c66258a1ff0fb27b8cffa95665c4

drbd: Do not full sync if a P_SYNC_UUID packet gets lost

See also commit from 2009-08-15
"drbd_uuid_compare(): Do not full sync in case a P_SYNC_UUID packet gets lost."

We saw cases where the History UUIDs where not as expected. So the
detection of the special case did not trigger. With the sync UUID
no longer being a random number, but deducible from the previous
bitmap UUID, the detection of this special case becomes more
reliable.

The SyncUUID now is the previous bitmap UUID + 0x1000000000000.

Rule 5a:
Cs = H1p & H1p + Offset = Bp
  Connection was lost before SyncUUID Packet came through.
  Corrent (peer) UUIDs:
   Bp = H1p
   H1p = H2p
   H2p = 0
  Become Sync target.

Rule 7a:
Cp = H1s & H1s + Offset = Bs
  Connection was lost before SyncUUID Packet came through.
  Correct (own) UUIDs:
   Bs = H1s
   H1s = H2s
   H2s = 0
  Become Sync source.

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