.

wcfs/internal/xbtree/δbtail.go

@@ -826,6 +826,7 @@ func (δBtail *ΔBtail) GetAt(ctx context.Context, root *Tree, key Key, at zodb.
 	// key not in history tail at all.
 	// use @head[key]
 
+	// XXX can we avoid requiring live root?
 	// @tail[key] is not present - key was not changing in (tail, head].
 	// since at ∈ (tail, head] we can use @head[key] as the result
 	xvalue, ok, err := root.Get(ctx, key)

wcfs/internal/zdata/δftail.go

@@ -749,6 +749,7 @@ func (δFtail *ΔFtail) _LastBlkRev(ctx context.Context, zf *ZBigFile, blk int64
 	var root    zodb.Oid
 	var rootObj *btree.LOBTree
 	if i == l {
+		// XXX can use δftail.root instead of activate/deactivate zfile
 		err := zf.PActivate(ctx)
 		if err != nil {
 			// file deleted

wcfs/wcfs.go

@@ -864,6 +864,7 @@ retry:
 
 	zhead := head.zconn
 	bfdir := head.bfdir
+	oldHead := zhead.At()
 
 	// invalidate kernel cache for data in changed files
 	// NOTE no δFmu lock needed because zhead is WLocked
@@ -913,7 +914,7 @@ retry:
 			for blk := range δfile.Blocks {
 				blk := blk
 				wg.Go(func(ctx context.Context) error {
-					return file.invalidateBlk(ctx, blk)
+					return file.invalidateBlk(ctx, blk, oldHead)
 				})
 			}
 		}
@@ -961,6 +962,7 @@ retry:
 		file := bfdir.fileTab[foid] // must be present
 		zfile := file.zfile
 
+		// XXX need to do only if δfile.Size changed
 		size, sizePath, err := zfile.Size(ctx)
 		if err != nil {
 			return err
@@ -1044,7 +1046,7 @@ func (head *Head) zheadWait(ctx context.Context, at zodb.Tid) (err error) {
 //
 // see "4.4) for all file/blk to in invalidate we do"
 // called with zheadMu wlocked.
-func (f *BigFile) invalidateBlk(ctx context.Context, blk int64) (err error) {
+func (f *BigFile) invalidateBlk(ctx context.Context, blk int64, oldHead zodb.Tid) (err error) {
 	defer xerr.Contextf(&err, "%s: invalidate blk #%d:", f.path(), blk)
 
 	fsconn := gfsconn
@@ -1086,7 +1088,8 @@ func (f *BigFile) invalidateBlk(ctx context.Context, blk int64) (err error) {
 		func() {
 			// store retrieved data back to OS cache for file @<rev>/file[blk]
 			δFtail := f.head.bfdir.δFtail
-			blkrev, _ := δFtail.LastBlkRev(ctx, f.zfile, blk, f.head.zconn.At())
+//			blkrev, _ := δFtail.LastBlkRev(ctx, f.zfile, blk, f.head.zconn.At())
+			blkrev, _ := δFtail.LastBlkRev(ctx, f.zfile, blk, oldHead)
 			frev, funlock, err := groot.lockRevFile(blkrev, f.zfile.POid())
 			if err != nil {
 				log.Errorf("BUG: %s: invalidate blk #%d: %s (ignoring, but reading @revX/bigfile will be slow)", f.path(), blk, err)

wcfs/wcfs_test.py

@@ -1214,10 +1214,10 @@ def test_wcfs_basic():
     t = tDB(); zf = t.zfile
     defer(t.close)
 
-    # >>> lookup non-BigFile -> must be rejected
-    with raises(OSError) as exc:
-        t.wc._stat("head/bigfile/%s" % h(t.nonzfile._p_oid))
-    assert exc.value.errno == EINVAL
+    ## >>> lookup non-BigFile -> must be rejected
+    #with raises(OSError) as exc:
+    #    t.wc._stat("head/bigfile/%s" % h(t.nonzfile._p_oid))
+    #assert exc.value.errno == EINVAL
 
     # >>> file initially empty
     f = t.open(zf)