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zfs: helper for ZFSGet guid and createtxg

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This commit is contained in:
Christian Schwarz 2019-10-14 17:48:47 +02:00
parent 18d2c350de
commit 0ba4b5eda6
2 changed files with 41 additions and 19 deletions
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23
zfs/replication_history.go
View File

@ -2,7 +2,6 @@ package zfs
import (
"fmt"
"strconv"
"github.com/pkg/errors"
)
@ -26,30 +25,18 @@ func ZFSGetReplicationCursor(fs *DatasetPath) (*FilesystemVersion, error) {
func ZFSSetReplicationCursor(fs *DatasetPath, snapname string) (guid uint64, err error) {
snapPath := fmt.Sprintf("%s@%s", fs.ToString(), snapname)
debug("replication cursor: snap path %q", snapPath)
propsSnap, err := zfsGet(snapPath, []string{"createtxg", "guid"}, sourceAny)
snapProps, err := ZFSGetCreateTXGAndGuid(snapPath)
if err != nil {
return 0, errors.Wrap(err, "zfs: replication cursor: get snapshot createtxg")
}
snapGuid, err := strconv.ParseUint(propsSnap.Get("guid"), 10, 64)
if err != nil {
return 0, errors.Wrap(err, "zfs: replication cursor: parse snapshot guid")
return 0, errors.Wrapf(err, "get properties of %q", snapPath)
}
bookmarkPath := fmt.Sprintf("%s#%s", fs.ToString(), ReplicationCursorBookmarkName)
propsBookmark, err := zfsGet(bookmarkPath, []string{"createtxg"}, sourceAny)
propsBookmark, err := ZFSGetCreateTXGAndGuid(bookmarkPath)
_, bookmarkNotExistErr := err.(*DatasetDoesNotExist)
if err != nil && !bookmarkNotExistErr {
return 0, errors.Wrap(err, "zfs: replication cursor: get bookmark txg")
}
if err == nil {
bookmarkTxg, err := strconv.ParseUint(propsBookmark.Get("createtxg"), 10, 64)
if err != nil {
return 0, errors.Wrap(err, "zfs: replication cursor: parse bookmark createtxg")
}
snapTxg, err := strconv.ParseUint(propsSnap.Get("createtxg"), 10, 64)
if err != nil {
return 0, errors.Wrap(err, "zfs: replication cursor: parse snapshot createtxg")
}
if snapTxg < bookmarkTxg {
if snapProps.CreateTXG < propsBookmark.CreateTXG {
return 0, errors.New("zfs: replication cursor: can only be advanced, not set back")
}
if err := ZFSDestroy(bookmarkPath); err != nil { // FIXME make safer by using new temporary bookmark, then rename, possible with channel programs
@ -59,5 +46,5 @@ func ZFSSetReplicationCursor(fs *DatasetPath, snapname string) (guid uint64, err
if err := ZFSBookmark(fs, snapname, ReplicationCursorBookmarkName); err != nil {
return 0, errors.Wrapf(err, "zfs: replication cursor: create bookmark")
}
return snapGuid, nil
return snapProps.Guid, nil
}

37
zfs/zfs.go
View File

@ -4,7 +4,6 @@ import (
"bufio"
"bytes"
"encoding/json"
"errors"
"fmt"
"io"
"os"
@ -20,6 +19,7 @@ import (
"github.com/prometheus/client_golang/prometheus"
"github.com/pkg/errors"
"github.com/zrepl/zrepl/util/envconst"
)
@ -1024,6 +1024,41 @@ func zfsGet(path string, props []string, allowedSources zfsPropertySource) (*ZFS
return res, nil
}
type ZFSPropCreateTxgAndGuidProps struct {
CreateTXG, Guid uint64
}
func ZFSGetCreateTXGAndGuid(ds string) (ZFSPropCreateTxgAndGuidProps, error) {
props, err := zfsGetNumberProps(ds, []string{"createtxg", "guid"}, sourceAny)
if err != nil {
return ZFSPropCreateTxgAndGuidProps{}, err
}
return ZFSPropCreateTxgAndGuidProps{
CreateTXG: props["createtxg"],
Guid: props["guid"],
}, nil
}
// returns *DatasetDoesNotExist if the dataset does not exist
func zfsGetNumberProps(ds string, props []string, src zfsPropertySource) (map[string]uint64, error) {
sps, err := zfsGet(ds, props, sourceAny)
if err != nil {
if _, ok := err.(*DatasetDoesNotExist); ok {
return nil, err // pass through as is
}
return nil, errors.Wrap(err, "zfs: set replication cursor: get snapshot createtxg")
}
r := make(map[string]uint64, len(props))
for _, p := range props {
v, err := strconv.ParseUint(sps.Get(p), 10, 64)
if err != nil {
return nil, errors.Wrapf(err, "zfs get: parse number property %q", p)
}
r[p] = v
}
return r, nil
}
type DestroySnapshotsError struct {
RawLines []string
Filesystem string