From 8839c5105a78ba97b0155634cdd09f1ac03f5a9e Mon Sep 17 00:00:00 2001 From: Krishnan Parthasarathi Date: Sun, 23 Oct 2016 22:27:52 +0530 Subject: [PATCH] Pass values to closures esp. when passed to defer statement. (#3050) opsID, a variable on the stack, changes over the course of Completemultipartupload function in xl-v1-multipart.go. This was being used in a function closure which was passed to defer statement. The variables used in the closure depend on their values at the time of evaluation which is indeterminate behaviour. It is incorrect to depend on values of variables on stack at the end of function, when deferred functions are executed. --- cmd/xl-v1-multipart.go | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/cmd/xl-v1-multipart.go b/cmd/xl-v1-multipart.go index 955138506..43e5e2cdc 100644 --- a/cmd/xl-v1-multipart.go +++ b/cmd/xl-v1-multipart.go @@ -760,19 +760,19 @@ func (xl xlObjects) CompleteMultipartUpload(bucket string, object string, upload // Hold write lock on the destination before rename. nsMutex.Lock(bucket, object, opsID) - defer func() { + defer func(curOpsID string) { // A new complete multipart upload invalidates any // previously cached object in memory. xl.objCache.Delete(path.Join(bucket, object)) // This lock also protects the cache namespace. - nsMutex.Unlock(bucket, object, opsID) + nsMutex.Unlock(bucket, object, curOpsID) // Prefetch the object from disk by triggering a fake GetObject call // Unlike a regular single PutObject, multipart PutObject is comes in // stages and it is harder to cache. go xl.GetObject(bucket, object, 0, objectSize, ioutil.Discard) - }() + }(opsID) // Rename if an object already exists to temporary location. uniqueID := getUUID()