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Implement placeholder filesystems.

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Note the docs on the placeholder user property introduced with this
commit. The solution is not really satisfying but couldn't think of a
better one OTOMH
This commit is contained in:
Christian Schwarz
2017-07-30 14:56:16 +02:00
parent 8eb4a2ba44
commit 4732fdd4cc
2 changed files with 117 additions and 24 deletions
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57
cmd/replication.go
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@ -243,19 +243,13 @@ func doPull(pull PullContext) (err error) {
return
}
// build mapping (local->RemoteLocalMapping) + traversal datastructure
type RemoteLocalMapping struct {
Remote zfs.DatasetPath
Local zfs.DatasetPath
LocalExists bool
Remote zfs.DatasetPath
Local zfs.DatasetPath
}
replMapping := make(map[string]RemoteLocalMapping, len(remoteFilesystems))
localTraversal := zfs.NewDatasetPathForest()
localExists, err := zfs.ZFSListFilesystemExists()
if err != nil {
log.Printf("cannot get local filesystems map: %s", err)
return err
}
{
log.Printf("mapping using %#v\n", pull.Mapping)
@ -270,13 +264,20 @@ func doPull(pull PullContext) (err error) {
}
continue
}
m := RemoteLocalMapping{remoteFilesystems[fs], localFs, localExists(localFs)}
m := RemoteLocalMapping{remoteFilesystems[fs], localFs}
replMapping[m.Local.ToString()] = m
localTraversal.Add(m.Local)
}
}
// get info about local filesystems
localFilesystemState, err := zfs.ZFSListFilesystemState()
if err != nil {
log.Printf("cannot get local filesystems map: %s", err)
return err
}
log.Printf("remoteFilesystems: %#v\nreplMapping: %#v\n", remoteFilesystems, replMapping)
// per fs sync, assume sorted in top-down order TODO
@ -284,12 +285,18 @@ func doPull(pull PullContext) (err error) {
localTraversal.WalkTopDown(func(v zfs.DatasetPathVisit) bool {
if v.FilledIn {
if localExists(v.Path) {
if _, exists := localFilesystemState[v.Path.ToString()]; exists {
// No need to verify if this is a placeholder or not. It is sufficient
// to know we can add child filesystems to it
return true
}
log.Printf("aborting, don't know how to create fill-in dataset %s", v.Path)
err = fmt.Errorf("aborting, don't know how to create fill-in dataset: %s", v.Path)
return false
log.Printf("creating placeholder filesystem %s", v.Path)
err = zfs.ZFSCreatePlaceholderFilesystem(v.Path)
if err != nil {
err = fmt.Errorf("aborting, cannot create placeholder filesystem %s: %s", v.Path, err)
return false
}
return true
}
m, ok := replMapping[v.Path.ToString()]
@ -303,8 +310,16 @@ func doPull(pull PullContext) (err error) {
log("mapping: %#v\n", m)
localState, localExists := localFilesystemState[m.Local.ToString()]
var versions []zfs.FilesystemVersion
if m.LocalExists {
switch {
case !localExists:
log("local filesystem does not exist")
case localState.Placeholder:
log("local filesystem is marked as placeholder")
default:
log("local filesystem exists, retrieving versions for diff")
if versions, err = zfs.ZFSListFilesystemVersions(m.Local, nil); err != nil {
log("cannot get filesystem versions, stopping...: %v\n", m.Local.ToString(), m, err)
return false
@ -323,6 +338,10 @@ func doPull(pull PullContext) (err error) {
diff := zfs.MakeFilesystemDiff(versions, theirVersions)
log("diff: %#v\n", diff)
if localState.Placeholder && diff.Conflict != zfs.ConflictAllRight {
panic("internal inconsistency: local placeholder implies ConflictAllRight")
}
switch diff.Conflict {
case zfs.ConflictAllRight:
@ -364,7 +383,13 @@ func doPull(pull PullContext) (err error) {
log("progress on receive operation: %v bytes received", p.TotalRX)
})
if err = zfs.ZFSRecv(m.Local, &watcher, "-u"); err != nil {
recvArgs := []string{"-u"}
if localState.Placeholder {
log("receive with forced rollback to replace placeholder filesystem")
recvArgs = append(recvArgs, "-F")
}
if err = zfs.ZFSRecv(m.Local, &watcher, recvArgs...); err != nil {
log("error receiving stream, stopping...: %s", err)
return false
}