On Thu 07-10-21 15:34:19, Miklos Szeredi wrote: > 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()? You could but then you'd have to make sure you have I_DIRTY_SYNC always set when I_DIRTY_PAGES is set on the upper inode so that your ->write_inode() callback gets called. Overall I agree the logic would be probably simpler. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
