Merge branch 'lukeshu/enums'

15 files changed, 284 insertions, 246 deletions

diff --git a/lib/btrfs/Makefile b/lib/btrfs/Makefile
index a1fe747..b98a1b7 100644
--- a/lib/btrfs/Makefile
+++ b/lib/btrfs/Makefile
@@ -77,16 +77,13 @@ btrfsprim/itemtype.go: btrfsitem/items.txt $(MAKEFILE_LIST)
 	  echo 'import "fmt"'; \
 	  echo 'type ItemType uint8'; \
 	  echo 'const ('; \
-	  sed -E 's,(.*)=([^:]*)(:.*)? (trivial|complex) (.*),\1_KEY=ItemType(\2),' $< | uniq; \
+	  sed -E 's,(.*)=([^:]*)(:.*)? (trivial|complex) (.*),\1_KEY ItemType=\2,' $< | uniq; \
 	  echo ')'; \
 	  echo 'func (t ItemType) String() string {'; \
-	  echo '  names := map[ItemType]string{'; \
-	  sed -E 's@(.*)=(.*) (trivial|complex) (.*)@\1_KEY: "\1",@' $< | sed 's/"UUID_/&KEY_/'; \
+	  echo '  switch t {'; \
+	  sed -E 's@(.*)=(.*) (trivial|complex) (.*)@case \1_KEY: return "\1"@' $< | sed 's/"UUID_/&KEY_/'; \
+	  echo '  default: return fmt.Sprintf("%d", t)'; \
 	  echo '  }'; \
-	  echo '  if name, ok := names[t]; ok {'; \
-	  echo '    return name'; \
-	  echo '  }'; \
-	  echo '  return fmt.Sprintf("%d", t)'; \
 	  echo '}'; \
 	} | gofmt >$@
 files += btrfsprim/itemtype.go
diff --git a/lib/btrfs/btrfsitem/item_dir.go b/lib/btrfs/btrfsitem/item_dir.go
index 0049072..c1b3c09 100644
--- a/lib/btrfs/btrfsitem/item_dir.go
+++ b/lib/btrfs/btrfsitem/item_dir.go
@@ -84,33 +84,34 @@ func (o DirEntry) MarshalBinary() ([]byte, error) {
 type FileType uint8
 
 const (
-	FT_UNKNOWN  = FileType(0)
-	FT_REG_FILE = FileType(1)
-	FT_DIR      = FileType(2)
-	FT_CHRDEV   = FileType(3)
-	FT_BLKDEV   = FileType(4)
-	FT_FIFO     = FileType(5)
-	FT_SOCK     = FileType(6)
-	FT_SYMLINK  = FileType(7)
-	FT_XATTR    = FileType(8)
+	FT_UNKNOWN FileType = iota
+	FT_REG_FILE
+	FT_DIR
+	FT_CHRDEV
+	FT_BLKDEV
+	FT_FIFO
+	FT_SOCK
+	FT_SYMLINK
+	FT_XATTR
 
-	FT_MAX = FileType(9)
+	FT_MAX
 )
 
+var fileTypeNames = []string{
+	"UNKNOWN",
+	"FILE", // NB: Just "FILE", despite corresponding to "REG_FILE"
+	"DIR",
+	"CHRDEV",
+	"BLKDEV",
+	"FIFO",
+	"SOCK",
+	"SYMLINK",
+	"XATTR",
+}
+
 func (ft FileType) String() string {
-	names := map[FileType]string{
-		FT_UNKNOWN:  "UNKNOWN",
-		FT_REG_FILE: "FILE", // XXX
-		FT_DIR:      "DIR",
-		FT_CHRDEV:   "CHRDEV",
-		FT_BLKDEV:   "BLKDEV",
-		FT_FIFO:     "FIFO",
-		FT_SOCK:     "SOCK",
-		FT_SYMLINK:  "SYMLINK",
-		FT_XATTR:    "XATTR",
-	}
-	if name, ok := names[ft]; ok {
-		return name
+	if ft < FT_MAX {
+		return fileTypeNames[ft]
 	}
 	return fmt.Sprintf("DIR_ITEM.%d", uint8(ft))
 }
diff --git a/lib/btrfs/btrfsitem/item_extent.go b/lib/btrfs/btrfsitem/item_extent.go
index 3789cfe..871ed90 100644
--- a/lib/btrfs/btrfsitem/item_extent.go
+++ b/lib/btrfs/btrfsitem/item_extent.go
@@ -111,7 +111,7 @@ type TreeBlockInfo struct {
 type ExtentFlags uint64
 
 const (
-	EXTENT_FLAG_DATA = ExtentFlags(1 << iota)
+	EXTENT_FLAG_DATA ExtentFlags = 1 << iota
 	EXTENT_FLAG_TREE_BLOCK
 )
 
diff --git a/lib/btrfs/btrfsitem/item_fileextent.go b/lib/btrfs/btrfsitem/item_fileextent.go
index 30a14ef..6b08897 100644
--- a/lib/btrfs/btrfsitem/item_fileextent.go
+++ b/lib/btrfs/btrfsitem/item_fileextent.go
@@ -101,11 +101,17 @@ func (o FileExtent) MarshalBinary() ([]byte, error) {
 type FileExtentType uint8
 
 const (
-	FILE_EXTENT_INLINE = FileExtentType(iota)
+	FILE_EXTENT_INLINE FileExtentType = iota
 	FILE_EXTENT_REG
 	FILE_EXTENT_PREALLOC
 )
 
+var fileExtentTypeNames = []string{
+	"inline",
+	"regular",
+	"prealloc",
+}
+
 func (o FileExtent) Size() (int64, error) {
 	switch o.Type {
 	case FILE_EXTENT_INLINE:
@@ -118,14 +124,9 @@ func (o FileExtent) Size() (int64, error) {
 }
 
 func (fet FileExtentType) String() string {
-	names := map[FileExtentType]string{
-		FILE_EXTENT_INLINE:   "inline",
-		FILE_EXTENT_REG:      "regular",
-		FILE_EXTENT_PREALLOC: "prealloc",
-	}
-	name, ok := names[fet]
-	if !ok {
-		name = "unknown"
+	name := "unknown"
+	if int(fet) < len(fileExtentTypeNames) {
+		name = fileExtentTypeNames[fet]
 	}
 	return fmt.Sprintf("%d (%s)", fet, name)
 }
@@ -133,22 +134,23 @@ func (fet FileExtentType) String() string {
 type CompressionType uint8
 
 const (
-	COMPRESS_NONE = CompressionType(iota)
+	COMPRESS_NONE CompressionType = iota
 	COMPRESS_ZLIB
 	COMPRESS_LZO
 	COMPRESS_ZSTD
 )
 
+var compressionTypeNames = []string{
+	"none",
+	"zlib",
+	"lzo",
+	"zstd",
+}
+
 func (ct CompressionType) String() string {
-	names := map[CompressionType]string{
-		COMPRESS_NONE: "none",
-		COMPRESS_ZLIB: "zlib",
-		COMPRESS_LZO:  "lzo",
-		COMPRESS_ZSTD: "zstd",
-	}
-	name, ok := names[ct]
-	if !ok {
-		name = "unknown"
+	name := "unknown"
+	if int(ct) < len(compressionTypeNames) {
+		name = compressionTypeNames[ct]
 	}
 	return fmt.Sprintf("%d (%s)", ct, name)
 }
diff --git a/lib/btrfs/btrfsitem/item_freespaceinfo.go b/lib/btrfs/btrfsitem/item_freespaceinfo.go
index 0699367..9b886af 100644
--- a/lib/btrfs/btrfsitem/item_freespaceinfo.go
+++ b/lib/btrfs/btrfsitem/item_freespaceinfo.go
@@ -20,7 +20,7 @@ type FreeSpaceInfo struct { // trivial FREE_SPACE_INFO=198
 type FreeSpaceFlags uint32
 
 const (
-	FREE_SPACE_USING_BITMAPS = FreeSpaceFlags(1 << iota)
+	FREE_SPACE_USING_BITMAPS FreeSpaceFlags = 1 << iota
 )
 
 var freeSpaceFlagNames = []string{
diff --git a/lib/btrfs/btrfsitem/item_inode.go b/lib/btrfs/btrfsitem/item_inode.go
index 69f8445..6951c76 100644
--- a/lib/btrfs/btrfsitem/item_inode.go
+++ b/lib/btrfs/btrfsitem/item_inode.go
@@ -36,7 +36,7 @@ type Inode struct { // trivial INODE_ITEM=1
 type InodeFlags uint64
 
 const (
-	INODE_NODATASUM = InodeFlags(1 << iota)
+	INODE_NODATASUM InodeFlags = 1 << iota
 	INODE_NODATACOW
 	INODE_READONLY
 	INODE_NOCOMPRESS
diff --git a/lib/btrfs/btrfsitem/item_root.go b/lib/btrfs/btrfsitem/item_root.go
index c0db900..d39bd70 100644
--- a/lib/btrfs/btrfsitem/item_root.go
+++ b/lib/btrfs/btrfsitem/item_root.go
@@ -48,7 +48,7 @@ type Root struct { // trivial ROOT_ITEM=132
 type RootFlags uint64
 
 const (
-	ROOT_SUBVOL_RDONLY = RootFlags(1 << iota)
+	ROOT_SUBVOL_RDONLY RootFlags = 1 << iota
 )
 
 var rootFlagNames = []string{
diff --git a/lib/btrfs/btrfsprim/itemtype.go b/lib/btrfs/btrfsprim/itemtype.go
index 0b6baee..f33179a 100644
--- a/lib/btrfs/btrfsprim/itemtype.go
+++ b/lib/btrfs/btrfsprim/itemtype.go
@@ -7,77 +7,107 @@ import "fmt"
 type ItemType uint8
 
 const (
-	BLOCK_GROUP_ITEM_KEY     = ItemType(192)
-	CHUNK_ITEM_KEY           = ItemType(228)
-	DEV_EXTENT_KEY           = ItemType(204)
-	DEV_ITEM_KEY             = ItemType(216)
-	DIR_INDEX_KEY            = ItemType(96)
-	DIR_ITEM_KEY             = ItemType(84)
-	EXTENT_CSUM_KEY          = ItemType(128)
-	EXTENT_DATA_KEY          = ItemType(108)
-	EXTENT_DATA_REF_KEY      = ItemType(178)
-	EXTENT_ITEM_KEY          = ItemType(168)
-	FREE_SPACE_BITMAP_KEY    = ItemType(200)
-	FREE_SPACE_EXTENT_KEY    = ItemType(199)
-	FREE_SPACE_INFO_KEY      = ItemType(198)
-	INODE_ITEM_KEY           = ItemType(1)
-	INODE_REF_KEY            = ItemType(12)
-	METADATA_ITEM_KEY        = ItemType(169)
-	ORPHAN_ITEM_KEY          = ItemType(48)
-	PERSISTENT_ITEM_KEY      = ItemType(249)
-	QGROUP_INFO_KEY          = ItemType(242)
-	QGROUP_LIMIT_KEY         = ItemType(244)
-	QGROUP_RELATION_KEY      = ItemType(246)
-	QGROUP_STATUS_KEY        = ItemType(240)
-	ROOT_BACKREF_KEY         = ItemType(144)
-	ROOT_ITEM_KEY            = ItemType(132)
-	ROOT_REF_KEY             = ItemType(156)
-	SHARED_BLOCK_REF_KEY     = ItemType(182)
-	SHARED_DATA_REF_KEY      = ItemType(184)
-	TREE_BLOCK_REF_KEY       = ItemType(176)
-	UNTYPED_KEY              = ItemType(0)
-	UUID_RECEIVED_SUBVOL_KEY = ItemType(252)
-	UUID_SUBVOL_KEY          = ItemType(251)
-	XATTR_ITEM_KEY           = ItemType(24)
+	BLOCK_GROUP_ITEM_KEY     ItemType = 192
+	CHUNK_ITEM_KEY           ItemType = 228
+	DEV_EXTENT_KEY           ItemType = 204
+	DEV_ITEM_KEY             ItemType = 216
+	DIR_INDEX_KEY            ItemType = 96
+	DIR_ITEM_KEY             ItemType = 84
+	EXTENT_CSUM_KEY          ItemType = 128
+	EXTENT_DATA_KEY          ItemType = 108
+	EXTENT_DATA_REF_KEY      ItemType = 178
+	EXTENT_ITEM_KEY          ItemType = 168
+	FREE_SPACE_BITMAP_KEY    ItemType = 200
+	FREE_SPACE_EXTENT_KEY    ItemType = 199
+	FREE_SPACE_INFO_KEY      ItemType = 198
+	INODE_ITEM_KEY           ItemType = 1
+	INODE_REF_KEY            ItemType = 12
+	METADATA_ITEM_KEY        ItemType = 169
+	ORPHAN_ITEM_KEY          ItemType = 48
+	PERSISTENT_ITEM_KEY      ItemType = 249
+	QGROUP_INFO_KEY          ItemType = 242
+	QGROUP_LIMIT_KEY         ItemType = 244
+	QGROUP_RELATION_KEY      ItemType = 246
+	QGROUP_STATUS_KEY        ItemType = 240
+	ROOT_BACKREF_KEY         ItemType = 144
+	ROOT_ITEM_KEY            ItemType = 132
+	ROOT_REF_KEY             ItemType = 156
+	SHARED_BLOCK_REF_KEY     ItemType = 182
+	SHARED_DATA_REF_KEY      ItemType = 184
+	TREE_BLOCK_REF_KEY       ItemType = 176
+	UNTYPED_KEY              ItemType = 0
+	UUID_RECEIVED_SUBVOL_KEY ItemType = 252
+	UUID_SUBVOL_KEY          ItemType = 251
+	XATTR_ITEM_KEY           ItemType = 24
 )
 
 func (t ItemType) String() string {
-	names := map[ItemType]string{
-		BLOCK_GROUP_ITEM_KEY:     "BLOCK_GROUP_ITEM",
-		CHUNK_ITEM_KEY:           "CHUNK_ITEM",
-		DEV_EXTENT_KEY:           "DEV_EXTENT",
-		DEV_ITEM_KEY:             "DEV_ITEM",
-		DIR_INDEX_KEY:            "DIR_INDEX",
-		DIR_ITEM_KEY:             "DIR_ITEM",
-		EXTENT_CSUM_KEY:          "EXTENT_CSUM",
-		EXTENT_DATA_KEY:          "EXTENT_DATA",
-		EXTENT_DATA_REF_KEY:      "EXTENT_DATA_REF",
-		EXTENT_ITEM_KEY:          "EXTENT_ITEM",
-		FREE_SPACE_BITMAP_KEY:    "FREE_SPACE_BITMAP",
-		FREE_SPACE_EXTENT_KEY:    "FREE_SPACE_EXTENT",
-		FREE_SPACE_INFO_KEY:      "FREE_SPACE_INFO",
-		INODE_ITEM_KEY:           "INODE_ITEM",
-		INODE_REF_KEY:            "INODE_REF",
-		METADATA_ITEM_KEY:        "METADATA_ITEM",
-		ORPHAN_ITEM_KEY:          "ORPHAN_ITEM",
-		PERSISTENT_ITEM_KEY:      "PERSISTENT_ITEM",
-		QGROUP_INFO_KEY:          "QGROUP_INFO",
-		QGROUP_LIMIT_KEY:         "QGROUP_LIMIT",
-		QGROUP_RELATION_KEY:      "QGROUP_RELATION",
-		QGROUP_STATUS_KEY:        "QGROUP_STATUS",
-		ROOT_BACKREF_KEY:         "ROOT_BACKREF",
-		ROOT_ITEM_KEY:            "ROOT_ITEM",
-		ROOT_REF_KEY:             "ROOT_REF",
-		SHARED_BLOCK_REF_KEY:     "SHARED_BLOCK_REF",
-		SHARED_DATA_REF_KEY:      "SHARED_DATA_REF",
-		TREE_BLOCK_REF_KEY:       "TREE_BLOCK_REF",
-		UNTYPED_KEY:              "UNTYPED",
-		UUID_RECEIVED_SUBVOL_KEY: "UUID_KEY_RECEIVED_SUBVOL",
-		UUID_SUBVOL_KEY:          "UUID_KEY_SUBVOL",
-		XATTR_ITEM_KEY:           "XATTR_ITEM",
+	switch t {
+	case BLOCK_GROUP_ITEM_KEY:
+		return "BLOCK_GROUP_ITEM"
+	case CHUNK_ITEM_KEY:
+		return "CHUNK_ITEM"
+	case DEV_EXTENT_KEY:
+		return "DEV_EXTENT"
+	case DEV_ITEM_KEY:
+		return "DEV_ITEM"
+	case DIR_INDEX_KEY:
+		return "DIR_INDEX"
+	case DIR_ITEM_KEY:
+		return "DIR_ITEM"
+	case EXTENT_CSUM_KEY:
+		return "EXTENT_CSUM"
+	case EXTENT_DATA_KEY:
+		return "EXTENT_DATA"
+	case EXTENT_DATA_REF_KEY:
+		return "EXTENT_DATA_REF"
+	case EXTENT_ITEM_KEY:
+		return "EXTENT_ITEM"
+	case FREE_SPACE_BITMAP_KEY:
+		return "FREE_SPACE_BITMAP"
+	case FREE_SPACE_EXTENT_KEY:
+		return "FREE_SPACE_EXTENT"
+	case FREE_SPACE_INFO_KEY:
+		return "FREE_SPACE_INFO"
+	case INODE_ITEM_KEY:
+		return "INODE_ITEM"
+	case INODE_REF_KEY:
+		return "INODE_REF"
+	case METADATA_ITEM_KEY:
+		return "METADATA_ITEM"
+	case ORPHAN_ITEM_KEY:
+		return "ORPHAN_ITEM"
+	case PERSISTENT_ITEM_KEY:
+		return "PERSISTENT_ITEM"
+	case QGROUP_INFO_KEY:
+		return "QGROUP_INFO"
+	case QGROUP_LIMIT_KEY:
+		return "QGROUP_LIMIT"
+	case QGROUP_RELATION_KEY:
+		return "QGROUP_RELATION"
+	case QGROUP_STATUS_KEY:
+		return "QGROUP_STATUS"
+	case ROOT_BACKREF_KEY:
+		return "ROOT_BACKREF"
+	case ROOT_ITEM_KEY:
+		return "ROOT_ITEM"
+	case ROOT_REF_KEY:
+		return "ROOT_REF"
+	case SHARED_BLOCK_REF_KEY:
+		return "SHARED_BLOCK_REF"
+	case SHARED_DATA_REF_KEY:
+		return "SHARED_DATA_REF"
+	case TREE_BLOCK_REF_KEY:
+		return "TREE_BLOCK_REF"
+	case UNTYPED_KEY:
+		return "UNTYPED"
+	case UUID_RECEIVED_SUBVOL_KEY:
+		return "UUID_KEY_RECEIVED_SUBVOL"
+	case UUID_SUBVOL_KEY:
+		return "UUID_KEY_SUBVOL"
+	case XATTR_ITEM_KEY:
+		return "XATTR_ITEM"
+	default:
+		return fmt.Sprintf("%d", t)
 	}
-	if name, ok := names[t]; ok {
-		return name
-	}
-	return fmt.Sprintf("%d", t)
 }
diff --git a/lib/btrfs/btrfsprim/misc.go b/lib/btrfs/btrfsprim/misc.go
index da661f6..ca2e313 100644
--- a/lib/btrfs/btrfsprim/misc.go
+++ b/lib/btrfs/btrfsprim/misc.go
@@ -22,8 +22,35 @@ type Key struct {
 	binstruct.End `bin:"off=0x11"`
 }
 
+// mimics print-tree.c:btrfs_print_key()
+func (key Key) Format(tree ObjID) string {
+	switch tree {
+	case UUID_TREE_OBJECTID:
+		return fmt.Sprintf("(%v %v %#08x)",
+			key.ObjectID.Format(tree),
+			key.ItemType,
+			key.Offset)
+	case ROOT_TREE_OBJECTID, QUOTA_TREE_OBJECTID:
+		return fmt.Sprintf("(%v %v %v)",
+			key.ObjectID.Format(tree),
+			key.ItemType,
+			ObjID(key.Offset).Format(tree))
+	default:
+		if key.Offset == math.MaxUint64 {
+			return fmt.Sprintf("(%v %v -1)",
+				key.ObjectID.Format(tree),
+				key.ItemType)
+		} else {
+			return fmt.Sprintf("(%v %v %v)",
+				key.ObjectID.Format(tree),
+				key.ItemType,
+				key.Offset)
+		}
+	}
+}
+
 func (key Key) String() string {
-	return fmt.Sprintf("{%v %v %v}", key.ObjectID, key.ItemType, key.Offset)
+	return key.Format(0)
 }
 
 var MaxKey = Key{
diff --git a/lib/btrfs/btrfsprim/objid.go b/lib/btrfs/btrfsprim/objid.go
index 8ad290b..1aea030 100644
--- a/lib/btrfs/btrfsprim/objid.go
+++ b/lib/btrfs/btrfsprim/objid.go
@@ -14,130 +14,111 @@ const maxUint64pp = 0x1_00000000_00000000
 
 const (
 	// The IDs of the various trees
-	ROOT_TREE_OBJECTID        = ObjID(1) // holds pointers to all of the tree roots
-	EXTENT_TREE_OBJECTID      = ObjID(2) // stores information about which extents are in use, and reference counts
-	CHUNK_TREE_OBJECTID       = ObjID(3) // chunk tree stores translations from logical -> physical block numbering
-	DEV_TREE_OBJECTID         = ObjID(4) // stores info about which areas of a given device are in use; one per device
-	FS_TREE_OBJECTID          = ObjID(5) // one per subvolume, storing files and directories
-	ROOT_TREE_DIR_OBJECTID    = ObjID(6) // directory objectid inside the root tree
-	CSUM_TREE_OBJECTID        = ObjID(7) // holds checksums of all the data extents
-	QUOTA_TREE_OBJECTID       = ObjID(8)
-	UUID_TREE_OBJECTID        = ObjID(9)  // for storing items that use the UUID_*_KEY
-	FREE_SPACE_TREE_OBJECTID  = ObjID(10) // tracks free space in block groups.
-	BLOCK_GROUP_TREE_OBJECTID = ObjID(11) // hold the block group items.
+	ROOT_TREE_OBJECTID        ObjID = 1 // holds pointers to all of the tree roots
+	EXTENT_TREE_OBJECTID      ObjID = 2 // stores information about which extents are in use, and reference counts
+	CHUNK_TREE_OBJECTID       ObjID = 3 // chunk tree stores translations from logical -> physical block numbering
+	DEV_TREE_OBJECTID         ObjID = 4 // stores info about which areas of a given device are in use; one per device
+	FS_TREE_OBJECTID          ObjID = 5 // one per subvolume, storing files and directories
+	ROOT_TREE_DIR_OBJECTID    ObjID = 6 // directory objectid inside the root tree
+	CSUM_TREE_OBJECTID        ObjID = 7 // holds checksums of all the data extents
+	QUOTA_TREE_OBJECTID       ObjID = 8
+	UUID_TREE_OBJECTID        ObjID = 9  // for storing items that use the UUID_*_KEY
+	FREE_SPACE_TREE_OBJECTID  ObjID = 10 // tracks free space in block groups.
+	BLOCK_GROUP_TREE_OBJECTID ObjID = 11 // hold the block group items.
 
 	// Objects in the DEV_TREE
-	DEV_STATS_OBJECTID = ObjID(0) // device stats in the device tree
+	DEV_STATS_OBJECTID ObjID = 0 // device stats in the device tree
 
 	// ???
-	BALANCE_OBJECTID         = ObjID(maxUint64pp - 4) // for storing balance parameters in the root tree
-	ORPHAN_OBJECTID          = ObjID(maxUint64pp - 5) // orphan objectid for tracking unlinked/truncated files
-	TREE_LOG_OBJECTID        = ObjID(maxUint64pp - 6) // does write ahead logging to speed up fsyncs
-	TREE_LOG_FIXUP_OBJECTID  = ObjID(maxUint64pp - 7)
-	TREE_RELOC_OBJECTID      = ObjID(maxUint64pp - 8) // space balancing
-	DATA_RELOC_TREE_OBJECTID = ObjID(maxUint64pp - 9)
-	EXTENT_CSUM_OBJECTID     = ObjID(maxUint64pp - 10) // extent checksums all have this objectid
-	FREE_SPACE_OBJECTID      = ObjID(maxUint64pp - 11) // For storing free space cache
-	FREE_INO_OBJECTID        = ObjID(maxUint64pp - 12) // stores the inode number for the free-ino cache
-
-	MULTIPLE_OBJECTIDS = ObjID(maxUint64pp - 255) // dummy objectid represents multiple objectids
+	BALANCE_OBJECTID         ObjID = maxUint64pp - 4 // for storing balance parameters in the root tree
+	ORPHAN_OBJECTID          ObjID = maxUint64pp - 5 // orphan objectid for tracking unlinked/truncated files
+	TREE_LOG_OBJECTID        ObjID = maxUint64pp - 6 // does write ahead logging to speed up fsyncs
+	TREE_LOG_FIXUP_OBJECTID  ObjID = maxUint64pp - 7
+	TREE_RELOC_OBJECTID      ObjID = maxUint64pp - 8 // space balancing
+	DATA_RELOC_TREE_OBJECTID ObjID = maxUint64pp - 9
+	EXTENT_CSUM_OBJECTID     ObjID = maxUint64pp - 10 // extent checksums all have this objectid
+	FREE_SPACE_OBJECTID      ObjID = maxUint64pp - 11 // For storing free space cache
+	FREE_INO_OBJECTID        ObjID = maxUint64pp - 12 // stores the inode number for the free-ino cache
+
+	MULTIPLE_OBJECTIDS ObjID = maxUint64pp - 255 // dummy objectid represents multiple objectids
 
 	// All files have objectids in this range.
-	FIRST_FREE_OBJECTID = ObjID(256)
-	LAST_FREE_OBJECTID  = ObjID(maxUint64pp - 256)
-
-	FIRST_CHUNK_TREE_OBJECTID = ObjID(256)
+	FIRST_FREE_OBJECTID ObjID = 256
+	LAST_FREE_OBJECTID  ObjID = maxUint64pp - 256
 
 	// Objects in the CHUNK_TREE
-	DEV_ITEMS_OBJECTID = ObjID(1)
+	DEV_ITEMS_OBJECTID        ObjID = 1
+	FIRST_CHUNK_TREE_OBJECTID ObjID = 256
 
 	// ???
-	EMPTY_SUBVOL_DIR_OBJECTID = ObjID(2)
+	EMPTY_SUBVOL_DIR_OBJECTID ObjID = 2
 )
 
-func (id ObjID) Format(typ ItemType) string {
-	switch typ {
-	case PERSISTENT_ITEM_KEY:
-		names := map[ObjID]string{
-			DEV_STATS_OBJECTID: "DEV_STATS",
-		}
-		if name, ok := names[id]; ok {
+var (
+	objidCommonNames = map[ObjID]string{
+		BALANCE_OBJECTID:         "BALANCE",
+		ORPHAN_OBJECTID:          "ORPHAN",
+		TREE_LOG_OBJECTID:        "TREE_LOG",
+		TREE_LOG_FIXUP_OBJECTID:  "TREE_LOG_FIXUP",
+		TREE_RELOC_OBJECTID:      "TREE_RELOC",
+		DATA_RELOC_TREE_OBJECTID: "DATA_RELOC_TREE",
+		EXTENT_CSUM_OBJECTID:     "EXTENT_CSUM",
+		FREE_SPACE_OBJECTID:      "FREE_SPACE",
+		FREE_INO_OBJECTID:        "FREE_INO",
+		MULTIPLE_OBJECTIDS:       "MULTIPLE",
+	}
+	objidDevTreeNames = map[ObjID]string{
+		DEV_STATS_OBJECTID: "DEV_STATS",
+	}
+	objidChunkTreeNames = map[ObjID]string{
+		DEV_ITEMS_OBJECTID:        "DEV_ITEMS",
+		FIRST_CHUNK_TREE_OBJECTID: "FIRST_CHUNK_TREE",
+	}
+	objidRootTreeNames = map[ObjID]string{
+		ROOT_TREE_OBJECTID:        "ROOT_TREE",
+		EXTENT_TREE_OBJECTID:      "EXTENT_TREE",
+		CHUNK_TREE_OBJECTID:       "CHUNK_TREE",
+		DEV_TREE_OBJECTID:         "DEV_TREE",
+		FS_TREE_OBJECTID:          "FS_TREE",
+		ROOT_TREE_DIR_OBJECTID:    "ROOT_TREE_DIR",
+		CSUM_TREE_OBJECTID:        "CSUM_TREE",
+		QUOTA_TREE_OBJECTID:       "QUOTA_TREE",
+		UUID_TREE_OBJECTID:        "UUID_TREE",
+		FREE_SPACE_TREE_OBJECTID:  "FREE_SPACE_TREE",
+		BLOCK_GROUP_TREE_OBJECTID: "BLOCK_GROUP_TREE",
+	}
+)
+
+func (id ObjID) Format(tree ObjID) string {
+	switch tree {
+	case DEV_TREE_OBJECTID:
+		if name, ok := objidDevTreeNames[id]; ok {
 			return name
 		}
 		return fmt.Sprintf("%d", int64(id))
-	case DEV_EXTENT_KEY:
-		return fmt.Sprintf("%d", int64(id))
-	case QGROUP_RELATION_KEY:
+	case QUOTA_TREE_OBJECTID:
+		if id == 0 {
+			return "0"
+		}
 		//nolint:gomnd // The left 48 bits are the "qgroup level", and the right 16 bits are the subvolume ID.
 		return fmt.Sprintf("%d/%d",
 			uint64(id)>>48,
 			uint64(id)&((1<<48)-1))
-	case UUID_SUBVOL_KEY, UUID_RECEIVED_SUBVOL_KEY:
+	case UUID_TREE_OBJECTID:
 		return fmt.Sprintf("%#016x", uint64(id))
-	case DEV_ITEM_KEY:
-		names := map[ObjID]string{
-			BALANCE_OBJECTID:         "BALANCE",
-			ORPHAN_OBJECTID:          "ORPHAN",
-			TREE_LOG_OBJECTID:        "TREE_LOG",
-			TREE_LOG_FIXUP_OBJECTID:  "TREE_LOG_FIXUP",
-			TREE_RELOC_OBJECTID:      "TREE_RELOC",
-			DATA_RELOC_TREE_OBJECTID: "DATA_RELOC_TREE",
-			EXTENT_CSUM_OBJECTID:     "EXTENT_CSUM",
-			FREE_SPACE_OBJECTID:      "FREE_SPACE",
-			FREE_INO_OBJECTID:        "FREE_INO",
-			MULTIPLE_OBJECTIDS:       "MULTIPLE",
-
-			DEV_ITEMS_OBJECTID: "DEV_ITEMS",
-		}
-		if name, ok := names[id]; ok {
+	case CHUNK_TREE_OBJECTID:
+		if name, ok := objidCommonNames[id]; ok {
 			return name
 		}
-		return fmt.Sprintf("%d", int64(id))
-	case CHUNK_ITEM_KEY:
-		names := map[ObjID]string{
-			BALANCE_OBJECTID:         "BALANCE",
-			ORPHAN_OBJECTID:          "ORPHAN",
-			TREE_LOG_OBJECTID:        "TREE_LOG",
-			TREE_LOG_FIXUP_OBJECTID:  "TREE_LOG_FIXUP",
-			TREE_RELOC_OBJECTID:      "TREE_RELOC",
-			DATA_RELOC_TREE_OBJECTID: "DATA_RELOC_TREE",
-			EXTENT_CSUM_OBJECTID:     "EXTENT_CSUM",
-			FREE_SPACE_OBJECTID:      "FREE_SPACE",
-			FREE_INO_OBJECTID:        "FREE_INO",
-			MULTIPLE_OBJECTIDS:       "MULTIPLE",
-
-			FIRST_CHUNK_TREE_OBJECTID: "FIRST_CHUNK_TREE",
-		}
-		if name, ok := names[id]; ok {
+		if name, ok := objidChunkTreeNames[id]; ok {
 			return name
 		}
 		return fmt.Sprintf("%d", int64(id))
 	default:
-		names := map[ObjID]string{
-			BALANCE_OBJECTID:         "BALANCE",
-			ORPHAN_OBJECTID:          "ORPHAN",
-			TREE_LOG_OBJECTID:        "TREE_LOG",
-			TREE_LOG_FIXUP_OBJECTID:  "TREE_LOG_FIXUP",
-			TREE_RELOC_OBJECTID:      "TREE_RELOC",
-			DATA_RELOC_TREE_OBJECTID: "DATA_RELOC_TREE",
-			EXTENT_CSUM_OBJECTID:     "EXTENT_CSUM",
-			FREE_SPACE_OBJECTID:      "FREE_SPACE",
-			FREE_INO_OBJECTID:        "FREE_INO",
-			MULTIPLE_OBJECTIDS:       "MULTIPLE",
-
-			ROOT_TREE_OBJECTID:        "ROOT_TREE",
-			EXTENT_TREE_OBJECTID:      "EXTENT_TREE",
-			CHUNK_TREE_OBJECTID:       "CHUNK_TREE",
-			DEV_TREE_OBJECTID:         "DEV_TREE",
-			FS_TREE_OBJECTID:          "FS_TREE",
-			ROOT_TREE_DIR_OBJECTID:    "ROOT_TREE_DIR",
-			CSUM_TREE_OBJECTID:        "CSUM_TREE",
-			QUOTA_TREE_OBJECTID:       "QUOTA_TREE",
-			UUID_TREE_OBJECTID:        "UUID_TREE",
-			FREE_SPACE_TREE_OBJECTID:  "FREE_SPACE_TREE",
-			BLOCK_GROUP_TREE_OBJECTID: "BLOCK_GROUP_TREE",
+		if name, ok := objidCommonNames[id]; ok {
+			return name
 		}
-		if name, ok := names[id]; ok {
+		if name, ok := objidRootTreeNames[id]; ok {
 			return name
 		}
 		return fmt.Sprintf("%d", int64(id))
@@ -145,5 +126,5 @@ func (id ObjID) Format(typ ItemType) string {
 }
 
 func (id ObjID) String() string {
-	return id.Format(UNTYPED_KEY)
+	return id.Format(0)
 }
diff --git a/lib/btrfs/btrfssum/csum.go b/lib/btrfs/btrfssum/csum.go
index f436e2c..157371e 100644
--- a/lib/btrfs/btrfssum/csum.go
+++ b/lib/btrfs/btrfssum/csum.go
@@ -52,35 +52,36 @@ func (csum CSum) Format(f fmt.State, verb rune) {
 type CSumType uint16
 
 const (
-	TYPE_CRC32 = CSumType(iota)
+	TYPE_CRC32 CSumType = iota
 	TYPE_XXHASH
 	TYPE_SHA256
 	TYPE_BLAKE2
 )
 
+var csumTypeNames = []string{
+	"crc32c",
+	"xxhash64",
+	"sha256",
+	"blake2",
+}
+
+var csumTypeSizes = []int{
+	4,
+	8,
+	32,
+	32,
+}
+
 func (typ CSumType) String() string {
-	names := map[CSumType]string{
-		TYPE_CRC32:  "crc32c",
-		TYPE_XXHASH: "xxhash64",
-		TYPE_SHA256: "sha256",
-		TYPE_BLAKE2: "blake2",
-	}
-	if name, ok := names[typ]; ok {
-		return name
+	if int(typ) < len(csumTypeNames) {
+		return csumTypeNames[typ]
 	}
 	return fmt.Sprintf("%d", typ)
 }
 
 func (typ CSumType) Size() int {
-	//nolint:gomnd // This is where we define the magic numbers.
-	sizes := map[CSumType]int{
-		TYPE_CRC32:  4,
-		TYPE_XXHASH: 8,
-		TYPE_SHA256: 32,
-		TYPE_BLAKE2: 32,
-	}
-	if size, ok := sizes[typ]; ok {
-		return size
+	if int(typ) < len(csumTypeSizes) {
+		return csumTypeSizes[typ]
 	}
 	return len(CSum{})
 }
diff --git a/lib/btrfs/btrfstree/path.go b/lib/btrfs/btrfstree/path.go
index d9bf216..dd2cb74 100644
--- a/lib/btrfs/btrfstree/path.go
+++ b/lib/btrfs/btrfstree/path.go
@@ -9,7 +9,6 @@ import (
 	"io"
 	"strings"
 
-	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsitem"
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
 )
@@ -104,7 +103,7 @@ func (path TreePath) String() string {
 		return "(empty-path)"
 	} else {
 		var ret strings.Builder
-		fmt.Fprintf(&ret, "%s->", path[0].FromTree.Format(btrfsitem.ROOT_ITEM_KEY))
+		fmt.Fprintf(&ret, "%s->", path[0].FromTree.Format(btrfsprim.ROOT_TREE_OBJECTID))
 		if len(path) == 1 && path[0] == (TreePathElem{FromTree: path[0].FromTree, FromItemIdx: -1}) {
 			ret.WriteString("(empty-path)")
 		} else {
diff --git a/lib/btrfs/btrfstree/types_node.go b/lib/btrfs/btrfstree/types_node.go
index fd4c939..0a89e05 100644
--- a/lib/btrfs/btrfstree/types_node.go
+++ b/lib/btrfs/btrfstree/types_node.go
@@ -58,7 +58,7 @@ var (
 )
 
 const (
-	NodeWritten = NodeFlags(1 << iota)
+	NodeWritten NodeFlags = 1 << iota
 	NodeReloc
 )
 
@@ -73,8 +73,8 @@ func (f NodeFlags) String() string         { return fmtutil.BitfieldString(f, no
 type BackrefRev uint8
 
 const (
-	OldBackrefRev   = BackrefRev(iota)
-	MixedBackrefRev = BackrefRev(iota)
+	OldBackrefRev BackrefRev = iota
+	MixedBackrefRev
 )
 
 // Node: main //////////////////////////////////////////////////////////////////////////////////////
diff --git a/lib/btrfs/btrfstree/types_superblock.go b/lib/btrfs/btrfstree/types_superblock.go
index 140d4a1..a9b1633 100644
--- a/lib/btrfs/btrfstree/types_superblock.go
+++ b/lib/btrfs/btrfstree/types_superblock.go
@@ -199,7 +199,7 @@ type RootBackup struct {
 type IncompatFlags uint64
 
 const (
-	FeatureIncompatMixedBackref = IncompatFlags(1 << iota)
+	FeatureIncompatMixedBackref IncompatFlags = 1 << iota
 	FeatureIncompatDefaultSubvol
 	FeatureIncompatMixedGroups
 	FeatureIncompatCompressLZO
diff --git a/lib/btrfs/btrfsvol/blockgroupflags.go b/lib/btrfs/btrfsvol/blockgroupflags.go
index 0125664..37442de 100644
--- a/lib/btrfs/btrfsvol/blockgroupflags.go
+++ b/lib/btrfs/btrfsvol/blockgroupflags.go
@@ -11,7 +11,7 @@ import (
 type BlockGroupFlags uint64
 
 const (
-	BLOCK_GROUP_DATA = BlockGroupFlags(1 << iota)
+	BLOCK_GROUP_DATA BlockGroupFlags = 1 << iota
 	BLOCK_GROUP_SYSTEM
 	BLOCK_GROUP_METADATA
 	BLOCK_GROUP_RAID0