asyncreader: Make StopBuffer as well as Abandon and fix confusion in callers

fs/accounting/accounting.go

@@ -128,6 +128,13 @@ func (acc *Account) GetAsyncReader() *asyncreader.AsyncReader {
 
 // StopBuffering stops the async buffer doing any more buffering
 func (acc *Account) StopBuffering() {
+	if asyncIn, ok := acc.in.(*asyncreader.AsyncReader); ok {
+		asyncIn.StopBuffering()
+	}
+}
+
+// Abandon stops the async buffer doing any more buffering
+func (acc *Account) Abandon() {
 	if asyncIn, ok := acc.in.(*asyncreader.AsyncReader); ok {
 		asyncIn.Abandon()
 	}
@@ -139,7 +146,7 @@ func (acc *Account) UpdateReader(in io.ReadCloser) {
 	acc.mu.Lock()
 	withBuf := acc.withBuf
 	if withBuf {
-		acc.StopBuffering()
+		acc.Abandon()
 		acc.withBuf = false
 	}
 	acc.in = in

fs/asyncreader/asyncreader.go

@@ -268,9 +268,15 @@ func (a *AsyncReader) SkipBytes(skip int) (ok bool) {
 	}
 }
 
-// Abandon will ensure that the underlying async reader is shut down.
-// It will NOT close the input supplied on New.
-func (a *AsyncReader) Abandon() {
+// StopBuffering will ensure that the underlying async reader is shut
+// down so no more is read from the input.
+//
+// This does not free the memory so Abandon() or Close() need to be
+// called on the input.
+//
+// This does not wait for Read/WriteTo to complete so can be called
+// concurrently to those.
+func (a *AsyncReader) StopBuffering() {
 	select {
 	case <-a.exit:
 		// Do nothing if reader routine already exited
@@ -280,6 +286,14 @@ func (a *AsyncReader) Abandon() {
 	// Close and wait for go routine
 	close(a.exit)
 	<-a.exited
+}
+
+// Abandon will ensure that the underlying async reader is shut down
+// and memory is returned. It does everything but close the input.
+//
+// It will NOT close the input supplied on New.
+func (a *AsyncReader) Abandon() {
+	a.StopBuffering()
 	// take the lock to wait for Read/WriteTo to complete
 	a.mu.Lock()
 	defer a.mu.Unlock()