Activate the flusher on every write

There's still room for optimisations: now flusher scans all inodes
and tries to flush any of them and it wastes a lot of time scanning.
A queue of "ready to flush" items could be much better.

internal/file.go

@@ -374,9 +374,9 @@ func (fh *FileHandle) WriteFile(offset int64, data []byte, copyData bool) (err e
 	fh.inode.lastWriteEnd = end
 	if fh.inode.CacheState == ST_CACHED {
 		fh.inode.SetCacheState(ST_MODIFIED)
-		// FIXME: Don't activate the flusher immediately for small writes
-		fh.inode.fs.WakeupFlusher()
 	}
+	// FIXME: Don't activate the flusher immediately for small writes
+	fh.inode.fs.WakeupFlusher()
 	fh.inode.Attributes.Mtime = time.Now()
 
 	fh.inode.mu.Unlock()

internal/goofys.go

@@ -469,6 +469,10 @@ func (fs *Goofys) WakeupFlusher() {
 // 3) Fsync triggered => intermediate full flush (same algorithm)
 // 4) Dirty memory limit reached => without on-disk cache we have to flush the whole object.
 //    With on-disk cache we can unload some dirty buffers to disk.
+//
+// FIXME There's still room for optimisations: now flusher scans all inodes
+// and tries to flush any of them and it wastes a lot of time scanning.
+// A queue of "ready to flush" items could be much better.
 func (fs *Goofys) Flusher() {
 	var inodes []fuseops.InodeID
 	again := false