From 0b5649278e39a068aaf91399941bab1b4a4a3cc2 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Wed, 9 Jun 2010 10:37:18 +1000 Subject: writeback: pay attention to wbc->nr_to_write in write_cache_pages If a filesystem writes more than one page in ->writepage, write_cache_pages fails to notice this and continues to attempt writeback when wbc->nr_to_write has gone negative - this trace was captured from XFS: wbc_writeback_start: towrt=1024 wbc_writepage: towrt=1024 wbc_writepage: towrt=0 wbc_writepage: towrt=-1 wbc_writepage: towrt=-5 wbc_writepage: towrt=-21 wbc_writepage: towrt=-85 This has adverse effects on filesystem writeback behaviour. write_cache_pages() needs to terminate after a certain number of pages are written, not after a certain number of calls to ->writepage are made. This is a regression introduced by 17bc6c30cf6bfffd816bdc53682dd46fc34a2cf4 ("vfs: Add no_nrwrite_index_update writeback control flag"), but cannot be reverted directly due to subsequent bug fixes that have gone in on top of it. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Linus Torvalds --- include/linux/writeback.h | 9 --------- 1 file changed, 9 deletions(-) (limited to 'include/linux/writeback.h') diff --git a/include/linux/writeback.h b/include/linux/writeback.h index f64134653a8..d63ef8f9609 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -56,15 +56,6 @@ struct writeback_control { unsigned for_reclaim:1; /* Invoked from the page allocator */ unsigned range_cyclic:1; /* range_start is cyclic */ unsigned more_io:1; /* more io to be dispatched */ - /* - * write_cache_pages() won't update wbc->nr_to_write and - * mapping->writeback_index if no_nrwrite_index_update - * is set. write_cache_pages() may write more than we - * requested and we want to make sure nr_to_write and - * writeback_index are updated in a consistent manner - * so we use a single control to update them - */ - unsigned no_nrwrite_index_update:1; }; /* -- cgit v1.2.3-70-g09d2