On 09/20/2017 08:41 AM, Jan Kara wrote: > On Tue 19-09-17 13:53:06, Jens Axboe wrote: >> Now that we have no external callers of wb_start_writeback(), >> we can move the nr_pages == 0 logic into that function. >> >> Signed-off-by: Jens Axboe <[email protected]> > > ... > >> +static unsigned long get_nr_dirty_pages(void) >> +{ >> + return global_node_page_state(NR_FILE_DIRTY) + >> + global_node_page_state(NR_UNSTABLE_NFS) + >> + get_nr_dirty_inodes(); >> +} >> + >> static void wb_start_writeback(struct bdi_writeback *wb, long nr_pages, >> bool range_cyclic, enum wb_reason reason) >> { >> @@ -942,6 +953,12 @@ static void wb_start_writeback(struct bdi_writeback >> *wb, long nr_pages, >> return; >> >> /* >> + * If someone asked for zero pages, we write out the WORLD >> + */ >> + if (!nr_pages) >> + nr_pages = get_nr_dirty_pages(); >> + > > So for 'wb' we have a better estimate of the amount we should write - use > wb_stat_sum(wb, WB_RECLAIMABLE) statistics - that is essentially dirty + > unstable_nfs broken down to bdi_writeback.
I don't mind making that change, but I think that should be a separate patch. We're using get_nr_dirty_pages() in existing locations where we have the 'wb', like in wb_check_old_data_flush(). -- Jens Axboe
