wip: rebuildmappings process: Don't require --pvlukeshu/process-without-pv

4 files changed, 90 insertions, 7 deletions

diff --git a/cmd/btrfs-rec/inspect/rebuildmappings/file_phony.go b/cmd/btrfs-rec/inspect/rebuildmappings/file_phony.go
new file mode 100644
index 0000000..a41a16b
--- /dev/null
+++ b/cmd/btrfs-rec/inspect/rebuildmappings/file_phony.go
@@ -0,0 +1,49 @@
+// Copyright (C) 2023  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package rebuildmappings
+
+import (
+	"fmt"
+
+	"git.lukeshu.com/btrfs-progs-ng/lib/binstruct"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfstree"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
+	"git.lukeshu.com/btrfs-progs-ng/lib/diskio"
+	"git.lukeshu.com/btrfs-progs-ng/lib/slices"
+)
+
+type phonyFile struct {
+	size btrfsvol.PhysicalAddr
+	sb   btrfstree.Superblock
+}
+
+var _ diskio.File[btrfsvol.PhysicalAddr] = (*phonyFile)(nil)
+
+func NewPhonyFile(size btrfsvol.PhysicalAddr, sb btrfstree.Superblock) *phonyFile {
+	return &phonyFile{
+		size: size,
+		sb:   sb,
+	}
+}
+
+func (f *phonyFile) Name() string                { return fmt.Sprintf("phony_file:device_id=%v", f.sb.DevItem.DevID) }
+func (f *phonyFile) Size() btrfsvol.PhysicalAddr { return f.size }
+func (*phonyFile) Close() error                  { return nil }
+
+func (f *phonyFile) ReadAt(p []byte, off btrfsvol.PhysicalAddr) (int, error) {
+	if len(p) == int(btrfs.SuperblockSize) && slices.Contains(off, btrfs.SuperblockAddrs) {
+		bs, err := binstruct.Marshal(f.sb)
+		if err != nil {
+			return 0, err
+		}
+		return copy(p, bs), nil
+	}
+	panic(fmt.Errorf("%T: should not happen: ReadAt should not be called for a phony file", f))
+}
+
+func (f *phonyFile) WriteAt([]byte, btrfsvol.PhysicalAddr) (int, error) {
+	panic(fmt.Errorf("%T: should not happen: WriteAt should not be called for a phony file", f))
+}
diff --git a/cmd/btrfs-rec/inspect_listnodes.go b/cmd/btrfs-rec/inspect_listnodes.go
index d9b24ed..eb088e8 100644
--- a/cmd/btrfs-rec/inspect_listnodes.go
+++ b/cmd/btrfs-rec/inspect_listnodes.go
@@ -28,7 +28,7 @@ func init() {
 			"to take advantage of the sector-by-sector scan that's already " +
 			"performed by `btrfs-rec inspect rebuild-mappings scan`.",
 		Args: cliutil.WrapPositionalArgs(cobra.ExactArgs(1)),
-		RunE: runWithRawFS(func(fs *btrfs.FS, cmd *cobra.Command, args []string) error {
+		RunE: runWithRawFS(nil, func(fs *btrfs.FS, cmd *cobra.Command, args []string) error {
 			ctx := cmd.Context()
 
 			nodeList, err := btrfsutil.ListNodes(ctx, fs)
diff --git a/cmd/btrfs-rec/inspect_rebuildmappings.go b/cmd/btrfs-rec/inspect_rebuildmappings.go
index e883b93..4c194c7 100644
--- a/cmd/btrfs-rec/inspect_rebuildmappings.go
+++ b/cmd/btrfs-rec/inspect_rebuildmappings.go
@@ -5,6 +5,7 @@
 package main
 
 import (
+	"fmt"
 	"os"
 
 	"git.lukeshu.com/go/lowmemjson"
@@ -37,7 +38,7 @@ func init() {
 			"\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 {
+		RunE: runWithRawFS(nil, func(fs *btrfs.FS, cmd *cobra.Command, args []string) error {
 			ctx := cmd.Context()
 
 			scanResults, err := rebuildmappings.ScanDevices(ctx, fs)
@@ -67,7 +68,7 @@ func init() {
 		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) {
+		RunE: runWithRawFS(nil, func(fs *btrfs.FS, cmd *cobra.Command, _ []string) (err error) {
 			ctx := cmd.Context()
 
 			devResults, err := rebuildmappings.ScanDevices(ctx, fs)
@@ -94,6 +95,7 @@ func init() {
 		}),
 	})
 
+	var scanResults rebuildmappings.ScanResult
 	cmd.AddCommand(&cobra.Command{
 		Use:   "process",
 		Short: "Rebuild the mappings based on previously read data",
@@ -108,6 +110,29 @@ func init() {
 			}
 			dlog.Infof(ctx, "... done reading %q", args[0])
 
+			pvDevices := fs.LV.PhysicalVolumes()
+			for _, devID := range maps.SortedKeys(scanResults.Devices) {
+				if maps.HasKey(pvDevices, devID) {
+					continue
+				}
+				devFile := &btrfs.Device{
+					File: rebuildmappings.NewPhonyFile(
+						scanResults.Devices[devID].Size,
+						scanResults.Devices[devID].Superblock.Val),
+				}
+				if err := fs.AddDevice(ctx, devFile); err != nil {
+					return fmt.Errorf("device file: %q: %w", devFile.Name(), err)
+				}
+			}
+			for _, mapping := range scanResults.Mappings {
+				if err := fs.LV.AddMapping(mapping); err != nil {
+					return err
+				}
+			}
+			return nil
+		}, func(fs *btrfs.FS, cmd *cobra.Command, _ []string) error {
+			ctx := cmd.Context()
+
 			if err := rebuildmappings.RebuildMappings(ctx, fs, scanResults.Devices); err != nil {
 				return err
 			}
diff --git a/cmd/btrfs-rec/main.go b/cmd/btrfs-rec/main.go
index 39ba9ef..30b7e3d 100644
--- a/cmd/btrfs-rec/main.go
+++ b/cmd/btrfs-rec/main.go
@@ -158,7 +158,10 @@ func run(runE func(*cobra.Command, []string) error) func(*cobra.Command, []strin
 	}
 }
 
-func runWithRawFS(runE func(*btrfs.FS, *cobra.Command, []string) error) func(*cobra.Command, []string) error {
+func runWithRawFS(
+	fallbackInit func(*btrfs.FS, *cobra.Command, []string) error,
+	runE func(*btrfs.FS, *cobra.Command, []string) error,
+) func(*cobra.Command, []string) error {
 	return run(func(cmd *cobra.Command, args []string) (err error) {
 		maybeSetErr := func(_err error) {
 			if _err != nil && err == nil {
@@ -166,7 +169,7 @@ func runWithRawFS(runE func(*btrfs.FS, *cobra.Command, []string) error) func(*co
 			}
 		}
 
-		if len(globalFlags.pvs) == 0 {
+		if len(globalFlags.pvs) == 0 && fallbackInit == nil {
 			// We do this here instead of calling argparser.MarkPersistentFlagRequired("pv") so that
 			// it doesn't interfere with the `help` sub-command.
 			return cliutil.FlagErrorFunc(cmd, fmt.Errorf("must specify 1 or more physical volumes with --pv"))
@@ -179,6 +182,12 @@ func runWithRawFS(runE func(*btrfs.FS, *cobra.Command, []string) error) func(*co
 			maybeSetErr(fs.Close())
 		}()
 
+		if fallbackInit != nil {
+			if err := fallbackInit(fs, cmd, args); err != nil {
+				return err
+			}
+		}
+
 		if globalFlags.mappings != "" {
 			mappingsJSON, err := readJSONFile[[]btrfsvol.Mapping](cmd.Context(), globalFlags.mappings)
 			if err != nil {
@@ -196,7 +205,7 @@ func runWithRawFS(runE func(*btrfs.FS, *cobra.Command, []string) error) func(*co
 }
 
 func runWithRawFSAndNodeList(runE func(*btrfs.FS, []btrfsvol.LogicalAddr, *cobra.Command, []string) error) func(*cobra.Command, []string) error {
-	return runWithRawFS(func(fs *btrfs.FS, cmd *cobra.Command, args []string) error {
+	return runWithRawFS(nil, func(fs *btrfs.FS, cmd *cobra.Command, args []string) error {
 		ctx := cmd.Context()
 
 		var nodeList []btrfsvol.LogicalAddr
@@ -245,7 +254,7 @@ func _runWithReadableFS(wantNodeList bool, runE func(btrfs.ReadableFS, []btrfsvo
 		if wantNodeList || globalFlags.rebuild || globalFlags.treeRoots != "" {
 			return runWithRawFSAndNodeList(inner)(cmd, args)
 		}
-		return runWithRawFS(func(fs *btrfs.FS, cmd *cobra.Command, args []string) error {
+		return runWithRawFS(nil, func(fs *btrfs.FS, cmd *cobra.Command, args []string) error {
 			return inner(fs, nil, cmd, args)
 		})(cmd, args)
 	}