diff options
Diffstat (limited to 'lib/btrfs/btrfsitem/item_blockgroup.go')
| -rw-r--r-- | lib/btrfs/btrfsitem/item_blockgroup.go | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/lib/btrfs/btrfsitem/item_blockgroup.go b/lib/btrfs/btrfsitem/item_blockgroup.go index ae0ca12..dc561bd 100644 --- a/lib/btrfs/btrfsitem/item_blockgroup.go +++ b/lib/btrfs/btrfsitem/item_blockgroup.go @@ -10,8 +10,20 @@ import ( "git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol" ) -// key.objectid = logical_addr -// key.offset = size of chunk +// A BlockGroup tracks allocation of the logical address space. +// +// Compare with: +// - DevExtents, which track allocation of the physical address space. +// - Chunks, which map logical addresses to physical addresses. +// +// The relationship between the three is +// +// DevExtent---[many:one]---Chunk---[one:one]---BlockGroup +// +// Key: +// +// key.objectid = logical_addr +// key.offset = size of chunk type BlockGroup struct { // trivial BLOCK_GROUP_ITEM=192 Used int64 `bin:"off=0, siz=8"` ChunkObjectID btrfsprim.ObjID `bin:"off=8, siz=8"` // always FIRST_CHUNK_TREE_OBJECTID |