cmd: add dump command to dump metadata to a file and load to load from a file

cmd/dump.go

@@ -0,0 +1,51 @@
+/*
+ * JuiceFS, Copyright (C) 2021 Juicedata, Inc.
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/juicedata/juicefs/pkg/meta"
+	"github.com/urfave/cli/v2"
+)
+
+func dump(ctx *cli.Context) error {
+	setLoggerLevel(ctx)
+	if ctx.Args().Len() < 1 {
+		return fmt.Errorf("META-ADDR is needed")
+	}
+	m := meta.NewClient(ctx.Args().Get(0), &meta.Config{Retries: 10, Strict: true})
+	fname := "juicefs-metadata.dump"
+	if ctx.Args().Len() > 1 {
+		fname = ctx.Args().Get(1)
+	}
+	fp, err := os.OpenFile(fname, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0644)
+	if err != nil {
+		return err
+	}
+	defer fp.Close()
+	return m.DumpMeta(fp)
+}
+
+func dumpFlags() *cli.Command {
+	return &cli.Command{
+		Name:      "dump",
+		Usage:     "dump JuiceFS metadata into a standalone file",
+		ArgsUsage: "META-ADDR [FILE (default: juicefs-metadata.dump)]",
+		Action:    dump,
+	}
+}

cmd/load.go

@@ -0,0 +1,50 @@
+/*
+ * JuiceFS, Copyright (C) 2021 Juicedata, Inc.
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+
+	"github.com/juicedata/juicefs/pkg/meta"
+	"github.com/urfave/cli/v2"
+)
+
+func load(ctx *cli.Context) error {
+	setLoggerLevel(ctx)
+	if ctx.Args().Len() < 1 {
+		return fmt.Errorf("META-ADDR is needed")
+	}
+	if ctx.Args().Len() < 2 {
+		return fmt.Errorf("FILE is needed")
+	}
+	m := meta.NewClient(ctx.Args().Get(0), &meta.Config{Retries: 10, Strict: true})
+	fname := ctx.Args().Get(1)
+	buf, err := ioutil.ReadFile(fname)
+	if err != nil {
+		return err
+	}
+	return m.LoadMeta(buf)
+}
+
+func loadFlags() *cli.Command {
+	return &cli.Command{
+		Name:      "load",
+		Usage:     "load JuiceFS metadata from a previously dumped file",
+		ArgsUsage: "META-ADDR FILE",
+		Action:    load,
+	}
+}

cmd/main.go

@@ -81,6 +81,8 @@ func main() {
 			profileFlags(),
 			statusFlags(),
 			warmupFlags(),
+			dumpFlags(),
+			loadFlags(),
 		},
 	}
 

pkg/meta/interface.go

@@ -16,6 +16,7 @@
 package meta
 
 import (
+	"io"
 	"os"
 	"strings"
 	"syscall"
@@ -106,6 +107,48 @@ func typeToStatType(_type uint8) uint32 {
 	}
 }
 
+func typeToString(_type uint8) string {
+	switch _type {
+	case TypeFile:
+		return "regular"
+	case TypeDirectory:
+		return "directory"
+	case TypeSymlink:
+		return "symlink"
+	case TypeFIFO:
+		return "fifo"
+	case TypeBlockDev:
+		return "blockdev"
+	case TypeCharDev:
+		return "chardev"
+	case TypeSocket:
+		return "socket"
+	default:
+		return "unknown"
+	}
+}
+
+func typeFromString(s string) uint8 {
+	switch s {
+	case "regular":
+		return TypeFile
+	case "directory":
+		return TypeDirectory
+	case "symlink":
+		return TypeSymlink
+	case "fifo":
+		return TypeFIFO
+	case "blockdev":
+		return TypeBlockDev
+	case "chardev":
+		return TypeCharDev
+	case "socket":
+		return TypeSocket
+	default:
+		panic(s)
+	}
+}
+
 // SMode is the file mode including type and unix permission.
 func (a Attr) SMode() uint32 {
 	return typeToStatType(a.Typ) | uint32(a.Mode)
@@ -254,6 +297,9 @@ type Meta interface {
 
 	// OnMsg add a callback for the given message type.
 	OnMsg(mtype uint32, cb MsgCallback)
+
+	DumpMeta(w io.Writer) error
+	LoadMeta(buf []byte) error
 }
 
 func removePassword(uri string) string {