* master: undo the stored record when a delete report arrives
Deleting a volume decremented the active count from the delete report's
ReadOnly flag, which the volume server never sets, so a volume the master
had already stopped counting as writable was uncounted a second time.
Every volume.move does this to its source, and the node, rack, DC and
topology counts drifted negative; the full-list path already used the
stored record. Undo exactly what was counted for the record held.
* volume: say whether a deleted volume was read-only
Explicit deletes, unmounts, collection deletes and the departures named
in a delta heartbeat all left ReadOnly unset, so an older master undid
the writable count for a volume it was no longer counting. Carry the
flags, as the Rust server already does.
Chris Lu
1c84f98cdf