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Diffstat (limited to 'pkg/sentry/fs/sync.go')
| -rw-r--r-- | pkg/sentry/fs/sync.go | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/pkg/sentry/fs/sync.go b/pkg/sentry/fs/sync.go new file mode 100644 index 000000000..9738a8f22 --- /dev/null +++ b/pkg/sentry/fs/sync.go @@ -0,0 +1,43 @@ +// Copyright 2018 Google Inc. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package fs + +// SyncType enumerates ways in which a File can be synced. +type SyncType int + +const ( + // SyncAll indicates that modified in-memory metadata and data should + // be written to backing storage. SyncAll implies SyncBackingStorage. + SyncAll SyncType = iota + + // SyncData indicates that along with modified in-memory data, only + // metadata needed to access that data needs to be written. + // + // For example, changes to access time or modification time do not + // need to be written because they are not necessary for a data read + // to be handled correctly, unlike the file size. + // + // The aim of SyncData is to reduce disk activity for applications + // that do not require all metadata to be synchronized with the disk, + // see fdatasync(2). File systems that implement SyncData as SyncAll + // do not support this optimization. + // + // SyncData implies SyncBackingStorage. + SyncData + + // SyncBackingStorage indicates that in-flight write operations to + // backing storage should be flushed. + SyncBackingStorage +) |