From 66f06a85acb70f278c87cbe17ecb07b85d559f85 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Miloslav=20Trma=C4=8D?= <mitr@redhat.com>
Date: Tue, 8 Nov 2022 16:10:21 +0100
Subject: [PATCH] Fix locking of containerStore.BigDataDigest
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It requires a WRITE lock.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>
---
 containers.go |  1 +
 store.go      | 16 +++++++---------
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/containers.go b/containers.go
index 3e0f4ddbc..7ec7e8acb 100644
--- a/containers.go
+++ b/containers.go
@@ -629,6 +629,7 @@ func (r *containerStore) BigDataSize(id, key string) (int64, error) {
 	return -1, ErrSizeUnknown
 }
 
+// Requires startWriting. Yes, really, WRITING (see SetBigData).
 func (r *containerStore) BigDataDigest(id, key string) (digest.Digest, error) {
 	if key == "" {
 		return "", fmt.Errorf("can't retrieve digest of container big data value with empty name: %w", ErrInvalidBigDataName)
diff --git a/store.go b/store.go
index f445957ac..0e4f9daf1 100644
--- a/store.go
+++ b/store.go
@@ -1968,15 +1968,13 @@ func (s *store) ContainerBigDataSize(id, key string) (int64, error) {
 }
 
 func (s *store) ContainerBigDataDigest(id, key string) (digest.Digest, error) {
-	rcstore, err := s.getContainerStore()
-	if err != nil {
-		return "", err
-	}
-	if err := rcstore.startReading(); err != nil {
-		return "", err
-	}
-	defer rcstore.stopReading()
-	return rcstore.BigDataDigest(id, key)
+	var res digest.Digest
+	err := s.writeToContainerStore(func(store rwContainerStore) error { // Yes, BigDataDigest requires a write lock.
+		var err error
+		res, err = store.BigDataDigest(id, key)
+		return err
+	})
+	return res, err
 }
 
 func (s *store) ContainerBigData(id, key string) ([]byte, error) {