move implementation to internal/ directory (#828)
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Christian Schwarz
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GitHub
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908807bd59
@@ -0,0 +1,197 @@
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package zfs
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import (
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"context"
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"crypto/sha512"
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"encoding/hex"
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"fmt"
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"github.com/pkg/errors"
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"github.com/zrepl/zrepl/internal/zfs/zfscmd"
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)
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const (
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// For a placeholder filesystem to be a placeholder, the property source must be local,
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// i.e. not inherited.
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PlaceholderPropertyName string = "zrepl:placeholder"
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placeholderPropertyOn string = "on"
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placeholderPropertyOff string = "off"
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)
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// computeLegacyPlaceholderPropertyValue is a legacy-compatibility function.
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//
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// In the 0.0.x series, the value stored in the PlaceholderPropertyName user property
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// was a hash value of the dataset path.
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// A simple `on|off` value could not be used at the time because `zfs list` was used to
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// list all filesystems and their placeholder state with a single command: due to property
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// inheritance, `zfs list` would print the placeholder state for all (non-placeholder) children
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// of a dataset, so the hash value was used to distinguish whether the property was local or
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// inherited.
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//
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// One of the drawbacks of the above approach is that `zfs rename` renders a placeholder filesystem
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// a non-placeholder filesystem if any of the parent path components change.
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//
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// We `zfs get` nowadays, which returns the property source, making the hash value no longer
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// necessary. However, we want to keep legacy compatibility.
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func computeLegacyHashBasedPlaceholderPropertyValue(p *DatasetPath) string {
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ps := []byte(p.ToString())
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sum := sha512.Sum512_256(ps)
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return hex.EncodeToString(sum[:])
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}
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// the caller asserts that placeholderPropertyValue is sourceLocal
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func isLocalPlaceholderPropertyValuePlaceholder(p *DatasetPath, placeholderPropertyValue string) (isPlaceholder bool) {
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legacy := computeLegacyHashBasedPlaceholderPropertyValue(p)
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switch placeholderPropertyValue {
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case legacy:
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return true
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case placeholderPropertyOn:
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return true
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default:
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return false
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}
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}
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type FilesystemPlaceholderState struct {
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FS string
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FSExists bool
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IsPlaceholder bool
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RawLocalPropertyValue string
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}
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// ZFSGetFilesystemPlaceholderState is the authoritative way to determine whether a filesystem
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// is a placeholder. Note that the property source must be `local` for the returned value to be valid.
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//
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// For nonexistent FS, err == nil and state.FSExists == false
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func ZFSGetFilesystemPlaceholderState(ctx context.Context, p *DatasetPath) (state *FilesystemPlaceholderState, err error) {
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state = &FilesystemPlaceholderState{FS: p.ToString()}
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state.FS = p.ToString()
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props, err := zfsGet(ctx, p.ToString(), []string{PlaceholderPropertyName}, SourceLocal)
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var _ error = (*DatasetDoesNotExist)(nil) // weak assertion on zfsGet's interface
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if _, ok := err.(*DatasetDoesNotExist); ok {
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return state, nil
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} else if err != nil {
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return state, err
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}
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state.FSExists = true
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state.RawLocalPropertyValue = props.Get(PlaceholderPropertyName)
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state.IsPlaceholder = isLocalPlaceholderPropertyValuePlaceholder(p, state.RawLocalPropertyValue)
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return state, nil
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}
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//go:generate enumer -type=FilesystemPlaceholderCreateEncryptionValue -trimprefix=FilesystemPlaceholderCreateEncryption
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type FilesystemPlaceholderCreateEncryptionValue int
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const (
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FilesystemPlaceholderCreateEncryptionInherit FilesystemPlaceholderCreateEncryptionValue = 1 << iota
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FilesystemPlaceholderCreateEncryptionOff
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)
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func ZFSCreatePlaceholderFilesystem(ctx context.Context, fs *DatasetPath, parent *DatasetPath, encryption FilesystemPlaceholderCreateEncryptionValue) (err error) {
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if fs.Length() == 1 {
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return fmt.Errorf("cannot create %q: pools cannot be created with zfs create", fs.ToString())
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}
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cmdline := []string{
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"create",
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"-o", fmt.Sprintf("%s=%s", PlaceholderPropertyName, placeholderPropertyOn),
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"-o", "mountpoint=none",
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}
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if !encryption.IsAFilesystemPlaceholderCreateEncryptionValue() {
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panic(encryption)
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}
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switch encryption {
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case FilesystemPlaceholderCreateEncryptionInherit:
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// no-op
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case FilesystemPlaceholderCreateEncryptionOff:
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cmdline = append(cmdline, "-o", "encryption=off")
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default:
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panic(encryption)
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}
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cmdline = append(cmdline, fs.ToString())
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cmd := zfscmd.CommandContext(ctx, ZFS_BINARY, cmdline...)
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stdio, err := cmd.CombinedOutput()
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if err != nil {
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err = &ZFSError{
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Stderr: stdio,
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WaitErr: err,
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}
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}
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return
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}
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func ZFSSetPlaceholder(ctx context.Context, p *DatasetPath, isPlaceholder bool) error {
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prop := placeholderPropertyOff
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if isPlaceholder {
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prop = placeholderPropertyOn
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}
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props := map[string]string{PlaceholderPropertyName: prop}
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return zfsSet(ctx, p.ToString(), props)
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}
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type MigrateHashBasedPlaceholderReport struct {
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OriginalState FilesystemPlaceholderState
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NeedsModification bool
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}
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// fs must exist, will panic otherwise
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func ZFSMigrateHashBasedPlaceholderToCurrent(ctx context.Context, fs *DatasetPath, dryRun bool) (*MigrateHashBasedPlaceholderReport, error) {
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st, err := ZFSGetFilesystemPlaceholderState(ctx, fs)
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if err != nil {
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return nil, fmt.Errorf("error getting placeholder state: %s", err)
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}
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if !st.FSExists {
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panic("inconsistent placeholder state returned: fs must exist")
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}
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report := MigrateHashBasedPlaceholderReport{
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OriginalState: *st,
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}
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report.NeedsModification = st.IsPlaceholder && st.RawLocalPropertyValue != placeholderPropertyOn
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if dryRun || !report.NeedsModification {
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return &report, nil
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}
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err = ZFSSetPlaceholder(ctx, fs, st.IsPlaceholder)
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if err != nil {
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return nil, fmt.Errorf("error re-writing placeholder property: %s", err)
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}
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return &report, nil
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}
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func ZFSListPlaceholderFilesystemsWithAdditionalProps(ctx context.Context, root string, additionalProps []string) (map[string]*ZFSProperties, error) {
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props := []string{PlaceholderPropertyName}
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if len(additionalProps) > 0 {
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props = append(props, additionalProps...)
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}
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propsByFS, err := zfsGetRecursive(ctx, root, -1, []string{"filesystem", "volume"}, props, SourceAny)
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if err != nil {
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return nil, errors.Wrapf(err, "cannot get placeholder filesystems under %q", root)
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}
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filtered := make(map[string]*ZFSProperties)
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for fs, props := range propsByFS {
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details := props.GetDetails(PlaceholderPropertyName)
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if details.Source != SourceLocal {
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continue
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}
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fsp, err := NewDatasetPath(fs)
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if err != nil {
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return nil, errors.Wrapf(err, "zfs get returned invalid dataset path %q", fs)
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}
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if !isLocalPlaceholderPropertyValuePlaceholder(fsp, details.Value) {
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continue
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}
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filtered[fs] = props
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}
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return filtered, nil
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}
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