From 641150f2a242d911d6418d1936b11a7129c605e1 Mon Sep 17 00:00:00 2001
From: Harshavardhana <harsha@minio.io>
Date: Sat, 10 Apr 2021 09:13:12 -0700
Subject: [PATCH] change updateVersion to only update keys, no deletes (#12032)

there are situations where metadata can have keys
with empty values, preserve existing behavior
---
 cmd/bucket-lifecycle.go     |  8 ++++++--
 cmd/erasure-metadata.go     |  5 ++++-
 cmd/xl-storage-format-v2.go | 12 ++----------
 3 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/cmd/bucket-lifecycle.go b/cmd/bucket-lifecycle.go
index 666f650fa..5bcc29698 100644
--- a/cmd/bucket-lifecycle.go
+++ b/cmd/bucket-lifecycle.go
@@ -623,7 +623,9 @@ func putRestoreOpts(bucket, object string, rreq *RestoreObjectRequest, objInfo O
 			}
 			meta[v.Name] = v.Value
 		}
-		meta[xhttp.AmzObjectTagging] = rreq.OutputLocation.S3.Tagging.String()
+		if tags := rreq.OutputLocation.S3.Tagging.String(); tags != "" {
+			meta[xhttp.AmzObjectTagging] = tags
+		}
 		if rreq.OutputLocation.S3.Encryption.EncryptionType != "" {
 			meta[xhttp.AmzServerSideEncryption] = xhttp.AmzEncryptionAES
 		}
@@ -636,7 +638,9 @@ func putRestoreOpts(bucket, object string, rreq *RestoreObjectRequest, objInfo O
 	for k, v := range objInfo.UserDefined {
 		meta[k] = v
 	}
-	meta[xhttp.AmzObjectTagging] = objInfo.UserTags
+	if len(objInfo.UserTags) != 0 {
+		meta[xhttp.AmzObjectTagging] = objInfo.UserTags
+	}
 
 	return ObjectOptions{
 		Versioned:        globalBucketVersioningSys.Enabled(bucket),
diff --git a/cmd/erasure-metadata.go b/cmd/erasure-metadata.go
index 9d07b8dd0..ddbee9ce3 100644
--- a/cmd/erasure-metadata.go
+++ b/cmd/erasure-metadata.go
@@ -138,7 +138,10 @@ func (fi FileInfo) ToObjectInfo(bucket, object string) ObjectInfo {
 	objInfo.ETag = extractETag(fi.Metadata)
 
 	// Add user tags to the object info
-	objInfo.UserTags = fi.Metadata[xhttp.AmzObjectTagging]
+	tags := fi.Metadata[xhttp.AmzObjectTagging]
+	if len(tags) != 0 {
+		objInfo.UserTags = tags
+	}
 
 	// Add replication status to the object info
 	objInfo.ReplicationStatus = replication.StatusType(fi.Metadata[xhttp.AmzBucketReplicationStatus])
diff --git a/cmd/xl-storage-format-v2.go b/cmd/xl-storage-format-v2.go
index 820cecea1..a77e5f9f8 100644
--- a/cmd/xl-storage-format-v2.go
+++ b/cmd/xl-storage-format-v2.go
@@ -739,17 +739,9 @@ func (z *xlMetaV2) UpdateObjectVersion(fi FileInfo) error {
 			if version.ObjectV2.VersionID == uv {
 				for k, v := range fi.Metadata {
 					if strings.HasPrefix(strings.ToLower(k), ReservedMetadataPrefixLower) {
-						if v == "" {
-							delete(z.Versions[i].ObjectV2.MetaSys, k)
-						} else {
-							z.Versions[i].ObjectV2.MetaSys[k] = []byte(v)
-						}
+						z.Versions[i].ObjectV2.MetaSys[k] = []byte(v)
 					} else {
-						if v == "" {
-							delete(z.Versions[i].ObjectV2.MetaUser, k)
-						} else {
-							z.Versions[i].ObjectV2.MetaUser[k] = v
-						}
+						z.Versions[i].ObjectV2.MetaUser[k] = v
 					}
 				}
 				if !fi.ModTime.IsZero() {