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zfs: FilesytemDiff: len(IncrementalPath) < 2 means same most recent version

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bonus: style + typo fixes
This commit is contained in:
Christian Schwarz 2017-05-07 12:09:06 +02:00
parent d0c0e2510b
commit 1a92717894
1 changed files with 14 additions and 11 deletions
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9
zfs/diff.go
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@ -62,7 +62,7 @@ type FilesystemDiff struct {
// The increments required to get left up to right's most recent version
// 0th element is the common ancestor, ordered by birthtime, oldest first
// If empty, left and right are at same most recent version
// If len() < 2, left and right are at same most recent version
// If nil, there is no incremental path for left to get to right's most recent version
// This means either (check Diverged field to determine which case we are in)
// a) no common ancestor (left deleted all the snapshots it previously transferred to right)
@ -150,6 +150,7 @@ func MakeFilesystemDiff(left, right []FilesystemVersion) (diff FilesystemDiff) {
}
// Assert both left and right are sorted by createtxg
{
var leftSorted, rightSorted fsbyCreateTXG
leftSorted = left
rightSorted = right
@ -159,8 +160,9 @@ func MakeFilesystemDiff(left, right []FilesystemVersion) (diff FilesystemDiff) {
if !sort.IsSorted(rightSorted) {
panic("cannot make filesystem diff: unsorted right")
}
}
// Find most recent common ancestor by name, preferring snapshots over bookmars
// Find most recent common ancestor by name, preferring snapshots over bookmarks
mrcaLeft := len(left) - 1
var mrcaRight int
outer:
@ -202,7 +204,8 @@ outer:
panic("invariant violated: mrca on left must be the last item in the left list")
}
// strip bookmarks going forward from right
// incPath must not contain bookmarks except initial one,
// and only if that initial bookmark's snapshot is gone
incPath := make([]FilesystemVersion, 0, len(right))
incPath = append(incPath, right[mrcaRight])
// right[mrcaRight] may be a bookmark if there's no equally named snapshot