diff options
Diffstat (limited to 'pkg/sentry/fs/save.go')
-rw-r--r-- | pkg/sentry/fs/save.go | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/pkg/sentry/fs/save.go b/pkg/sentry/fs/save.go new file mode 100644 index 000000000..bf2a85143 --- /dev/null +++ b/pkg/sentry/fs/save.go @@ -0,0 +1,77 @@ +// 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 + +import ( + "fmt" + "syscall" + + "gvisor.googlesource.com/gvisor/pkg/log" +) + +// SaveInodeMappings saves a mapping of path -> inode ID for every +// user-reachable Dirent. +// +// The entire kernel must be frozen to call this, and filesystem state must not +// change between SaveInodeMappings and state.Save, otherwise the saved state +// of any MountSource may be incoherent. +func SaveInodeMappings() { + mountsSeen := make(map[*MountSource]struct{}) + for dirent := range allDirents.dirents { + if _, ok := mountsSeen[dirent.Inode.MountSource]; !ok { + dirent.Inode.MountSource.ResetInodeMappings() + mountsSeen[dirent.Inode.MountSource] = struct{}{} + } + } + + for dirent := range allDirents.dirents { + if dirent.Inode != nil { + // We cannot trust the root provided in the mount due + // to the overlay. We can trust the overlay to delegate + // SaveInodeMappings to the right underlying + // filesystems, though. + root := dirent + for !root.mounted && root.parent != nil { + root = root.parent + } + + // Add the mapping. + n, reachable := dirent.FullName(root) + if !reachable { + // Something has gone seriously wrong if we can't reach our root. + panic(fmt.Sprintf("Unreachable root on dirent file %s", n)) + } + dirent.Inode.MountSource.SaveInodeMapping(dirent.Inode, n) + } + } +} + +// SaveFileFsyncError converts an fs.File.Fsync error to an error that +// indicates that the fs.File was not synced sufficiently to be saved. +func SaveFileFsyncError(err error) error { + switch err { + case nil: + // We succeeded, everything is great. + return nil + case syscall.EBADF, syscall.EINVAL, syscall.EROFS, syscall.ENOSYS, syscall.EPERM: + // These errors mean that the underlying node might not be syncable, + // which we expect to be reported as such even from the gofer. + log.Infof("failed to sync during save: %v", err) + return nil + default: + // We failed in some way that indicates potential data loss. + return fmt.Errorf("failed to sync: %v, data loss may occur", err) + } +} |