Previously, restoreState in NewDriver would restore volumes AND perform
FUSE mounts synchronously before the Docker plugin socket was created.
This caused two problems:
1. The monChan was created after restoreState, but mount() sends on
monChan, causing a deadlock (send on nil channel blocks forever).
2. Even with the channel fix, slow or hanging mounts during state
restore would block the server socket from being created, causing
Docker to time out after ~13 seconds with "no such file or
directory" for the plugin socket.
Fix by:
- Moving monChan creation and monitor goroutine start before
restoreState
- Splitting state restore into two phases: restoreState (metadata +
filesystem setup only) and RestoreMounts (actual FUSE mounts)
- Calling RestoreMounts asynchronously after the server starts
listening
- Performing mount restoration concurrently across volumes
Fixes#9231
Nick Craig-Wood
560d3928d0