On Thu, 7 Oct 2021 at 15:10, Chengguang Xu <cgxu519@xxxxxxxxxxxx> wrote: > > However that wasn't what I was asking about. AFAICS ->write_inode() > > won't start write back for dirty pages. Maybe I'm missing something, > > but there it looks as if nothing will actually trigger writeback for > > dirty pages in upper inode. > > > > Actually, page writeback on upper inode will be triggered by overlayfs ->writepages and > overlayfs' ->writepages will be called by vfs writeback function (i.e writeback_sb_inodes). Right. But wouldn't it be simpler to do this from ->write_inode()? I.e. call write_inode_now() as suggested by Jan. Also could just call mark_inode_dirty() on the overlay inode regardless of the dirty flags on the upper inode since it shouldn't matter and results in simpler logic. Thanks, Miklos > > Thanks, > Chengguang > > >
