On 2017/7/6 下午11:24, Christoph Hellwig wrote: > On Thu, Jul 06, 2017 at 03:35:48PM +0800, Coly Li wrote: >> Then gfs2 breaks the above rule ? in gfs2_metapath_ra() and >> gfs2_dir_readahead(), only REQ_META is used in submit_bh(). It seems an >> extra REQ_PRIO should be there. > > Or maybe not. E.g. XFS absolutely avoids using REQ_PRIO for any of > the buffer writeback as it does not have priority. You'll need to > ask gfs2 folks if they want this I/O to have priority or not. > I see. Just sent a RFC patch to gfs2 development list, and wait for response. Thanks for the hint.