1 files changed, 67 insertions, 4 deletions
diff --git a/cmd/btrfs-rec/inspect_rebuildmappings.go b/cmd/btrfs-rec/inspect_rebuildmappings.go
index 81660b0..55e3408 100644
--- a/cmd/btrfs-rec/inspect_rebuildmappings.go
+++ b/cmd/btrfs-rec/inspect_rebuildmappings.go
@@ -17,8 +17,8 @@ import (
 )
 
 func init() {
-	inspectors.AddCommand(&cobra.Command{
-		Use:   "rebuild-mappings SCAN_RESULT.json",
+	cmd := &cobra.Command{
+		Use:   "rebuild-mappings",
 		Short: "Rebuild broken chunk/dev-extent/blockgroup trees",
 		Long: "" +
 			"The rebuilt information is printed as JSON on stdout, and can\n" +
@@ -27,8 +27,69 @@ func init() {
 			"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)),
+			"out-of-band to stdout.\n" +
+			"\n" +
+			"The I/O and the CPU parts of this can be split up as:\n" +
+			"\n" +
+			"\tbtrfs-rec inspect rebuild-mappings scan > SCAN.json   # read\n" +
+			"\tbtrfs-rec inspect rebuild-mappings process SCAN.json  # CPU\n",
+		Args: cliutil.WrapPositionalArgs(cobra.NoArgs),
+		RunE: runWithRawFS(func(fs *btrfs.FS, cmd *cobra.Command, args []string) error {
+			ctx := cmd.Context()
+
+			scanResults, err := rebuildmappings.ScanDevices(ctx, fs)
+			if err != nil {
+				return err
+			}
+
+			if err := rebuildmappings.RebuildMappings(ctx, fs, scanResults); err != nil {
+				return err
+			}
+
+			dlog.Infof(ctx, "Writing reconstructed mappings to stdout...")
+			if err := writeJSONFile(os.Stdout, fs.LV.Mappings(), lowmemjson.ReEncoderConfig{
+				Indent:                "\t",
+				ForceTrailingNewlines: true,
+				CompactIfUnder:        120, //nolint:gomnd // This is what looks nice.
+			}); err != nil {
+				return err
+			}
+			dlog.Info(ctx, "... done writing")
+
+			return nil
+		}),
+	}
+
+	cmd.AddCommand(&cobra.Command{
+		Use:   "scan",
+		Short: "Read from the filesystem all data nescessary to rebuild the mappings",
+		Args:  cliutil.WrapPositionalArgs(cobra.NoArgs),
+		RunE: runWithRawFS(func(fs *btrfs.FS, cmd *cobra.Command, _ []string) (err error) {
+			ctx := cmd.Context()
+
+			scanResults, err := rebuildmappings.ScanDevices(ctx, fs)
+			if err != nil {
+				return err
+			}
+
+			dlog.Info(ctx, "Writing scan results to stdout...")
+			if err := writeJSONFile(os.Stdout, scanResults, lowmemjson.ReEncoderConfig{
+				Indent:                "\t",
+				ForceTrailingNewlines: true,
+				CompactIfUnder:        16, //nolint:gomnd // This is what looks nice.
+			}); err != nil {
+				return err
+			}
+			dlog.Info(ctx, "... done writing")
+
+			return nil
+		}),
+	})
+
+	cmd.AddCommand(&cobra.Command{
+		Use:   "process",
+		Short: "Rebuild the mappings based on previously read data",
+		Args:  cliutil.WrapPositionalArgs(cobra.ExactArgs(1)),
 		RunE: runWithRawFS(func(fs *btrfs.FS, cmd *cobra.Command, args []string) error {
 			ctx := cmd.Context()
 
@@ -56,4 +117,6 @@ func init() {
 			return nil
 		}),
 	})
+
+	inspectors.AddCommand(cmd)
 }