From 74994a2ec199ced5cc2db2f1628d95113d08fe8f Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Tue, 9 Jun 2015 17:29:25 +0100
Subject: [PATCH] Fix uploading big files which was causing timeouts or panics

The symtom was one of these two on upload of files only
  * panic: d.nx != 0 in crypto/md5.(*digest).checkSum
  * read tcp: i/o timeout

It turned out to be a combination of two upstream bugs

  * https://github.com/mreiferson/go-httpclient/commit/5a2187309eac92103d0329aaae48e06837f260fb
  * https://groups.google.com/forum/#!topic/golang-dev/0Nl6k5Sj6UU

This commit contains a work-around for the second problem, I've fixed
the first and had the change accepted upstream.
---
 fs/accounting.go | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/accounting.go b/fs/accounting.go
index 8dc674b2f..5f2dfb8a4 100644
--- a/fs/accounting.go
+++ b/fs/accounting.go
@@ -187,6 +187,12 @@ func (s *StatsInfo) DoneTransferring(o Object) {
 
 // Account limits and accounts for one transfer
 type Account struct {
+	// The mutex is to make sure Read() and Close() aren't called
+	// concurrently.  Unfortunately the persistent connection loop
+	// in http transport calls Read() after Do() returns on
+	// CancelRequest so this race can happen when it apparently
+	// shouldn't.
+	mu    sync.Mutex
 	in    io.ReadCloser
 	bytes int64
 }
@@ -200,6 +206,8 @@ func NewAccount(in io.ReadCloser) *Account {
 
 // Read bytes from the object - see io.Reader
 func (file *Account) Read(p []byte) (n int, err error) {
+	file.mu.Lock()
+	defer file.mu.Unlock()
 	n, err = file.in.Read(p)
 	file.bytes += int64(n)
 	Stats.Bytes(int64(n))
@@ -215,6 +223,8 @@ func (file *Account) Read(p []byte) (n int, err error) {
 
 // Close the object
 func (file *Account) Close() error {
+	file.mu.Lock()
+	defer file.mu.Unlock()
 	// FIXME do something?
 	return file.in.Close()
 }