[#1905] shard: Don't log read-only errors of write-cache

There is no need to log `writecache.ErrReadOnly` errors in `Delete`
method of the `Shard`.

Signed-off-by: Leonard Lyubich <ctulhurider@gmail.com>

pkg/local_object_storage/shard/delete.go

@@ -1,8 +1,11 @@
 package shard
 
 import (
+	"errors"
+
 	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/blobstor/common"
 	meta "github.com/nspcc-dev/neofs-node/pkg/local_object_storage/metabase"
+	"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/writecache"
 	oid "github.com/nspcc-dev/neofs-sdk-go/object/id"
 	"go.uber.org/zap"
 )
@@ -39,7 +42,7 @@ func (s *Shard) Delete(prm DeletePrm) (DeleteRes, error) {
 	for i := range prm.addr {
 		if s.hasWriteCache() {
 			err := s.writeCache.Delete(prm.addr[i])
-			if err != nil && !IsErrNotFound(err) {
+			if err != nil && !IsErrNotFound(err) && !errors.Is(err, writecache.ErrReadOnly) {
 				s.log.Warn("can't delete object from write cache", zap.String("error", err.Error()))
 			}
 		}

pkg/local_object_storage/writecache/writecache.go

@@ -23,6 +23,12 @@ type Info struct {
 type Cache interface {
 	Get(address oid.Address) (*object.Object, error)
 	Head(oid.Address) (*object.Object, error)
+	// Delete removes object referenced by the given oid.Address from the
+	// Cache. Returns any error encountered that prevented the object to be
+	// removed.
+	//
+	// Returns apistatus.ObjectNotFound if object is missing in the Cache.
+	// Returns ErrReadOnly if the Cache is currently in the read-only mode.
 	Delete(oid.Address) error
 	Iterate(IterationPrm) error
 	Put(common.PutPrm) (common.PutRes, error)