X FUSE lookup deadlock should be hopefully fixed

wcfs/wcfs.go

@@ -1043,7 +1043,7 @@ func (f *BigFile) invalidateBlk(ctx context.Context, blk int64) (err error) {
 		func() {
 			// store retrieved data back to OS cache for file @<rev>/file[blk]
 			//
-			// FIXME there is deadlock here:
+			// XXX there is deadlock here:
 			//
 			// T1: Lookup "head"
 			//	-> nodefs.rawBridge.lookupLock.Lock
@@ -1056,6 +1056,8 @@ func (f *BigFile) invalidateBlk(ctx context.Context, blk int64) (err error) {
 			//
 			// see https://github.com/hanwen/go-fuse/commit/d0fca860
 			// for when rawBridge.lookupLock was introduced.
+			//
+			// -> should be fixed: https://review.gerrithub.io/c/hanwen/go-fuse/+/487809
 			blkrev, _ := f.LastBlkRev(ctx, blk, f.head.zconn.At())
 			frev, funlock, err := groot.lockRevFile(blkrev, f.zfile.POid())
 			if err != nil {