Fix freelist corruption on tx.WriteTo

[heyitsanthony]

lol

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@f4ebd07). Click here to learn what that means.
The diff coverage is 100%.

@@            Coverage Diff            @@
##             master      #67   +/-   ##
=========================================
  Coverage          ?   85.47%           
=========================================
  Files             ?        9           
  Lines             ?     1859           
  Branches          ?        0           
=========================================
  Hits              ?     1589           
  Misses            ?      160           
  Partials          ?      110

Impacted Files	Coverage Δ
freelist.go	81.7% <100%> (ø)

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[xiang90]

@jpbetz

[jpbetz]

lgtm

[jpbetz]

@gyuho @xiang90 Can we cut a new bbolt version containing this fix?

[gyuho]

@jpbetz https://github.com/coreos/bbolt/releases/tag/v1.3.1-coreos.5 :)

Thanks @heyitsanthony !

[ahrtr]

It can fix the issue, but it's a little complicated. No need to handle freelist as a special case. I think it can be as simple as below.

$ git diff
diff --git a/freelist.go b/freelist.go
index fdf8a36..4a15832 100644
--- a/freelist.go
+++ b/freelist.go
@@ -118,9 +118,6 @@ func (f *freelist) free(txid common.Txid, p *common.Page) {
        allocTxid, ok := f.allocs[p.Id()]
        if ok {
                delete(f.allocs, p.Id())
-       } else if p.IsFreelistPage() {
-               // Freelist is always allocated by prior tx.
-               allocTxid = txid - 1
        }
 
        for id := p.Id(); id <= p.Id()+common.Pgid(p.Overflow()); id++ {