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// Copyright (C) 2022 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package main
import (
"encoding/json"
"fmt"
"io"
"os"
"github.com/datawire/dlib/dlog"
"github.com/datawire/ocibuild/pkg/cliutil"
"github.com/spf13/cobra"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfsprogs/btrfsinspect"
"git.lukeshu.com/btrfs-progs-ng/lib/maps"
)
func init() {
inspectors = append(inspectors, subcommand{
Command: cobra.Command{
Use: "rebuild-mappings SCAN_RESULT.json",
Short: "Rebuild broken chunk/dev-extent/blockgroup trees",
Long: "" +
"The rebuilt information is printed as JSON on stdout, and can\n" +
"be loaded by the --mappings flag.\n" +
"\n" +
"This is very similar to `btrfs rescue chunk-recover`, but (1)\n" +
"does a better job, (2) is less buggy, and (3) doesn't actually\n" +
"write the info back to the filesystem; instead writing it\n" +
"out-of-band to stdout.",
Args: cliutil.WrapPositionalArgs(cobra.ExactArgs(1)),
},
RunE: func(fs *btrfs.FS, cmd *cobra.Command, args []string) error {
ctx := cmd.Context()
scanResultsBytes, err := os.ReadFile(args[0])
if err != nil {
return err
}
var scanResults map[btrfsvol.DeviceID]btrfsinspect.ScanOneDevResult
if err := json.Unmarshal(scanResultsBytes, &scanResults); err != nil {
return err
}
devices := fs.LV.PhysicalVolumes()
for _, devID := range maps.SortedKeys(scanResults) {
dev, ok := devices[devID]
if !ok {
return fmt.Errorf("device ID %v mentioned in %q is not part of the filesystem",
devID, args[0])
}
dlog.Infof(ctx, "Rebuilding mappings from results on device %v...",
dev.Name())
scanResults[devID].AddToLV(ctx, fs, dev)
}
dlog.Infof(ctx, "Writing reconstructed mappings to stdout...")
if err := writeMappingsJSON(os.Stdout, fs); err != nil {
return err
}
return nil
},
})
}
func writeMappingsJSON(w io.Writer, fs *btrfs.FS) error {
mappings := fs.LV.Mappings()
if _, err := io.WriteString(w, "[\n"); err != nil {
return err
}
for i, mapping := range mappings {
suffix := ","
if i == len(mappings)-1 {
suffix = ""
}
bs, err := json.Marshal(mapping)
if err != nil {
return err
}
if _, err := fmt.Printf(" %s%s\n", bs, suffix); err != nil {
return err
}
}
if _, err := io.WriteString(w, "]\n"); err != nil {
return err
}
return nil
}
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