From 7766c5c90b1ef8fe45a31bba1467823cfdcc06d6 Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Mon, 18 Nov 2019 12:19:44 +0000
Subject: [PATCH] accounting: fix memory leak on retries operations

Before this change if an operation was retried on operations.Copy and
the operation was large enough to use an async buffer then an async
buffer was leaked on the retry.  This leaked memory, a file handle and
a go routine.

After this change if Account.WithBuffer is called and there is already
a buffer, then a new one won't be allocated.
---
 fs/accounting/accounting.go | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/accounting/accounting.go b/fs/accounting/accounting.go
index 11018c199..d1ae045e2 100644
--- a/fs/accounting/accounting.go
+++ b/fs/accounting/accounting.go
@@ -70,6 +70,10 @@ func newAccountSizeName(stats *StatsInfo, in io.ReadCloser, size int64, name str
 
 // WithBuffer - If the file is above a certain size it adds an Async reader
 func (acc *Account) WithBuffer() *Account {
+	// if already have a buffer then just return
+	if acc.withBuf {
+		return acc
+	}
 	acc.withBuf = true
 	var buffers int
 	if acc.size >= int64(fs.Config.BufferSize) || acc.size == -1 {
@@ -118,14 +122,16 @@ func (acc *Account) StopBuffering() {
 // async buffer (if any) and re-adding it
 func (acc *Account) UpdateReader(in io.ReadCloser) {
 	acc.mu.Lock()
-	if acc.withBuf {
+	withBuf := acc.withBuf
+	if withBuf {
 		acc.StopBuffering()
+		acc.withBuf = false
 	}
 	acc.in = in
 	acc.close = in
 	acc.origIn = in
 	acc.closed = false
-	if acc.withBuf {
+	if withBuf {
 		acc.WithBuffer()
 	}
 	acc.mu.Unlock()