From d0f4cc89a5d0ca45e7ba00fbb7733c2fead3f44e Mon Sep 17 00:00:00 2001
From: Klaus Post <klauspost@gmail.com>
Date: Fri, 10 Feb 2023 19:48:39 +0100
Subject: [PATCH] Re-add Veeam Listing workaround (#16593)

---
 cmd/erasure-server-pool.go   | 12 ++++++++++++
 cmd/metacache-server-pool.go |  4 +++-
 cmd/metacache-set.go         |  1 +
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/cmd/erasure-server-pool.go b/cmd/erasure-server-pool.go
index 63597169f..5e8d70895 100644
--- a/cmd/erasure-server-pool.go
+++ b/cmd/erasure-server-pool.go
@@ -1207,6 +1207,7 @@ func (z *erasureServerPools) ListObjectVersions(ctx context.Context, bucket, pre
 	if marker == "" && versionMarker != "" {
 		return loi, NotImplemented{}
 	}
+
 	opts := listPathOptions{
 		Bucket:      bucket,
 		Prefix:      prefix,
@@ -1217,6 +1218,17 @@ func (z *erasureServerPools) ListObjectVersions(ctx context.Context, bucket, pre
 		AskDisks:    globalAPIConfig.getListQuorum(),
 		Versioned:   true,
 	}
+
+	// Shortcut for APN/1.0 Veeam/1.0 Backup/10.0
+	// It requests unique blocks with a specific prefix.
+	// We skip scanning the parent directory for
+	// more objects matching the prefix.
+	ri := logger.GetReqInfo(ctx)
+	if ri != nil && strings.Contains(ri.UserAgent, `1.0 Veeam/1.0 Backup`) && strings.HasSuffix(prefix, ".blk") {
+		opts.BaseDir = prefix
+		opts.Transient = true
+	}
+
 	// set bucket metadata in opts
 	opts.setBucketMeta(ctx)
 
diff --git a/cmd/metacache-server-pool.go b/cmd/metacache-server-pool.go
index 6135020eb..38cbff39e 100644
--- a/cmd/metacache-server-pool.go
+++ b/cmd/metacache-server-pool.go
@@ -96,7 +96,9 @@ func (z *erasureServerPools) listPath(ctx context.Context, o *listPathOptions) (
 
 	// Decode and get the optional list id from the marker.
 	o.parseMarker()
-	o.BaseDir = baseDirFromPrefix(o.Prefix)
+	if o.BaseDir == "" {
+		o.BaseDir = baseDirFromPrefix(o.Prefix)
+	}
 	o.Transient = o.Transient || isReservedOrInvalidBucket(o.Bucket, false)
 	o.SetFilter()
 	if o.Transient {
diff --git a/cmd/metacache-set.go b/cmd/metacache-set.go
index 9d4e9f231..cce78e24d 100644
--- a/cmd/metacache-set.go
+++ b/cmd/metacache-set.go
@@ -49,6 +49,7 @@ type listPathOptions struct {
 	Bucket string
 
 	// Directory inside the bucket.
+	// When unset listPath will set this based on Prefix
 	BaseDir string
 
 	// Scan/return only content with prefix.