1 files changed, 54 insertions, 0 deletions
diff --git a/pkg/btrfsmisc/fsck.go b/pkg/btrfsmisc/fsck.go
new file mode 100644
index 0000000..527329d
--- /dev/null
+++ b/pkg/btrfsmisc/fsck.go
@@ -0,0 +1,54 @@
+package btrfsmisc
+
+import (
+	"fmt"
+
+	"lukeshu.com/btrfs-tools/pkg/binstruct"
+	"lukeshu.com/btrfs-tools/pkg/btrfs"
+	"lukeshu.com/btrfs-tools/pkg/util"
+)
+
+// ScanForNodes mimics btrfs-progs
+// cmds/rescue-chunk-recover.c:scan_one_device(), except it doesn't do
+// anything but log when it finds a node.
+func ScanForNodes(dev *btrfs.Device, sb btrfs.Superblock) error {
+	devSize, err := dev.Size()
+	if err != nil {
+		return err
+	}
+
+	if sb.NodeSize < sb.SectorSize {
+		return fmt.Errorf("node_size(%d) < sector_size(%d)",
+			sb.NodeSize, sb.SectorSize)
+	}
+
+	nodeBuf := make([]byte, sb.NodeSize)
+	for pos := btrfs.PhysicalAddr(0); pos+btrfs.PhysicalAddr(sb.SectorSize) < devSize; pos += btrfs.PhysicalAddr(sb.SectorSize) {
+		if util.InSlice(pos, btrfs.SuperblockAddrs) {
+			fmt.Printf("sector@%d is a superblock\n", pos)
+			continue
+		}
+		if _, err := dev.ReadAt(nodeBuf, pos); err != nil {
+			return fmt.Errorf("sector@%d: %w", pos, err)
+		}
+		var nodeHeader btrfs.NodeHeader
+		if _, err := binstruct.Unmarshal(nodeBuf, &nodeHeader); err != nil {
+			return fmt.Errorf("sector@%d: %w", pos, err)
+		}
+		if !nodeHeader.MetadataUUID.Equal(sb.EffectiveMetadataUUID()) {
+			//fmt.Printf("sector@%d does not look like a node\n", pos)
+			continue
+		}
+		if !nodeHeader.Checksum.Equal(btrfs.CRC32c(nodeBuf[0x20:])) {
+			fmt.Printf("sector@%d looks like a node but is corrupt (checksum doesn't match)\n", pos)
+			continue
+		}
+
+		fmt.Printf("node@%d: physical_addr=0x%0X logical_addr=0x%0X generation=%d owner=%v level=%d\n",
+			pos, pos, nodeHeader.Addr, nodeHeader.Generation, nodeHeader.Owner, nodeHeader.Level)
+
+		pos += btrfs.PhysicalAddr(sb.NodeSize) - btrfs.PhysicalAddr(sb.SectorSize)
+	}
+
+	return nil
+}