From: Dave Chinner Date: Tue, 24 Aug 2010 01:44:56 +0000 (+1000) Subject: xfs: handle negative wbc->nr_to_write during sync writeback X-Git-Tag: v3.0~3498^2~5 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=efceab1d563153a2b1a6e7d35376241a48126989;p=platform%2Fkernel%2Flinux-amlogic.git 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 --- diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c index 15412fe..528be1b 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);