kvserver: remove the replica.mu.draining field

It was only used in one rando place. Generally everybody looks at the
store's draing status.

Release note: None

pkg/kv/kvserver/replica.go

@@ -483,11 +483,6 @@ type Replica struct {
  // depending on which lock is being held.
  stateLoader stateloader.StateLoader
 
- // draining specifies whether this replica is draining. Raft leadership
- // transfers due to a lease change will be attempted even if the target does
- // not have all the log entries.
- draining bool
-
  // cachedProtectedTS provides the state of the protected timestamp
  // subsystem as used on the request serving path to determine the effective
  // gc threshold given the current TTL when using strict GC enforcement.
@@ -1606,7 +1601,7 @@ func (r *Replica) maybeTransferRaftLeadershipToLeaseholderLocked(ctx context.Con
  }
  lhReplicaID := uint64(lease.Replica.ReplicaID)
  lhProgress, ok := raftStatus.Progress[lhReplicaID]
- if (ok && lhProgress.Match >= raftStatus.Commit) || r.mu.draining {
+ if (ok && lhProgress.Match >= raftStatus.Commit) || r.store.IsDraining() {
  log.VEventf(ctx, 1, "transferring raft leadership to replica ID %v", lhReplicaID)
  r.store.metrics.RangeRaftLeaderTransfers.Inc(1)
  r.mu.internalRaftGroup.TransferLeader(lhReplicaID)

pkg/kv/kvserver/store.go

@@ -1034,12 +1034,6 @@ func (s *Store) AnnotateCtx(ctx context.Context) context.Context {
 func (s *Store) SetDraining(drain bool, reporter func(int, redact.SafeString)) {
  s.draining.Store(drain)
  if !drain {
- newStoreReplicaVisitor(s).Visit(func(r *Replica) bool {
- r.mu.Lock()
- r.mu.draining = false
- r.mu.Unlock()
- return true
- })
  return
  }
 
@@ -1110,10 +1104,6 @@ func (s *Store) SetDraining(drain bool, reporter func(int, redact.SafeString)) {
  default:
  }
 
- r.mu.Lock()
- r.mu.draining = true
- r.mu.Unlock()
-
  var drainingLease roachpb.Lease
  for {
  var llHandle *leaseRequestHandle