From efceab1d563153a2b1a6e7d35376241a48126989 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Tue, 24 Aug 2010 11:44:56 +1000 Subject: [PATCH] xfs: handle negative wbc->nr_to_write during sync writeback During data integrity (WB_SYNC_ALL) writeback, wbc->nr_to_write will go negative on inodes with more than 1024 dirty pages due to implementation details of write_cache_pages(). Currently XFS will abort page clustering in writeback once nr_to_write drops below zero, and so for data integrity writeback we will do very inefficient page at a time allocation and IO submission for inodes with large numbers of dirty pages. Fix this by only aborting the page clustering code when wbc->nr_to_write is negative and the sync mode is WB_SYNC_NONE. Cc: Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig --- fs/xfs/linux-2.6/xfs_aops.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c index 15412fe15c3a..528be1ba1402 100644 --- a/fs/xfs/linux-2.6/xfs_aops.c +++ b/fs/xfs/linux-2.6/xfs_aops.c @@ -852,8 +852,8 @@ xfs_convert_page( SetPageUptodate(page); if (count) { - wbc->nr_to_write--; - if (wbc->nr_to_write <= 0) + if (--wbc->nr_to_write <= 0 && + wbc->sync_mode == WB_SYNC_NONE) done = 1; } xfs_start_page_writeback(page, !page_dirty, count); -- 2.20.1