diff options
author | Luke Shumaker <lukeshu@lukeshu.com> | 2022-07-10 13:18:30 -0600 |
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committer | Luke Shumaker <lukeshu@lukeshu.com> | 2022-07-10 13:35:20 -0600 |
commit | 27401b6ea459921a6152ab1744da1618358465f4 (patch) | |
tree | 2c4f9c096f1a593e65d7f824901e815ca48bfaf0 /lib/btrfs/btrfsvol/devext.go | |
parent | 42f6f78e0a32ba0eda707154f8e1ffb4579604ee (diff) |
Rename the module, mv pkg lib
Diffstat (limited to 'lib/btrfs/btrfsvol/devext.go')
-rw-r--r-- | lib/btrfs/btrfsvol/devext.go | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/lib/btrfs/btrfsvol/devext.go b/lib/btrfs/btrfsvol/devext.go new file mode 100644 index 0000000..43c6255 --- /dev/null +++ b/lib/btrfs/btrfsvol/devext.go @@ -0,0 +1,89 @@ +package btrfsvol + +import ( + "fmt" + + "git.lukeshu.com/btrfs-progs-ng/lib/util" +) + +// physical => logical +type devextMapping struct { + PAddr PhysicalAddr + LAddr LogicalAddr + Size AddrDelta + SizeLocked bool + Flags *BlockGroupFlags +} + +// return -1 if 'a' is wholly to the left of 'b' +// return 0 if there is some overlap between 'a' and 'b' +// return 1 if 'a is wholly to the right of 'b' +func (a devextMapping) cmpRange(b devextMapping) int { + switch { + case a.PAddr.Add(a.Size) <= b.PAddr: + // 'a' is wholly to the left of 'b'. + return -1 + case b.PAddr.Add(b.Size) <= a.PAddr: + // 'a' is wholly to the right of 'b'. + return 1 + default: + // There is some overlap. + return 0 + } +} + +func (a devextMapping) union(rest ...devextMapping) (devextMapping, error) { + // sanity check + for _, ext := range rest { + if a.cmpRange(ext) != 0 { + return devextMapping{}, fmt.Errorf("devexts don't overlap") + } + } + exts := append([]devextMapping{a}, rest...) + // figure out the physical range (.PAddr and .Size) + beg := exts[0].PAddr + end := beg.Add(exts[0].Size) + for _, ext := range exts { + beg = util.Min(beg, ext.PAddr) + end = util.Max(end, ext.PAddr.Add(ext.Size)) + } + ret := devextMapping{ + PAddr: beg, + Size: end.Sub(beg), + } + for _, ext := range exts { + if ext.SizeLocked { + ret.SizeLocked = true + if ret.Size != ext.Size { + return devextMapping{}, fmt.Errorf("member devext has locked size=%v, but union would have size=%v", + ext.Size, ret.Size) + } + } + } + // figure out the logical range (.LAddr) + first := true + for _, ext := range exts { + offsetWithinRet := ext.PAddr.Sub(ret.PAddr) + laddr := ext.LAddr.Add(-offsetWithinRet) + if first { + ret.LAddr = laddr + } else if laddr != ret.LAddr { + return ret, fmt.Errorf("devexts don't agree on laddr: %v != %v", ret.LAddr, laddr) + } + } + // figure out the flags (.Flags) + for _, ext := range exts { + if ext.Flags == nil { + continue + } + if ret.Flags == nil { + val := *ext.Flags + ret.Flags = &val + } + if *ret.Flags != *ext.Flags { + return ret, fmt.Errorf("mismatch flags: %v != %v", *ret.Flags, *ext.Flags) + } + } + // done + return ret, nil +} |