From 515f4a037fb9ab736f8bad733fcd2ffd350cf265 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Tue, 6 Jan 2009 14:39:10 -0800 Subject: [PATCH] mm: write_cache_pages optimise page cleaning In write_cache_pages, if we get stuck behind another process that is cleaning pages, we will be forced to wait for them to finish, then perform our own writeout (if it was redirtied during the long wait), then wait for that. If a page under writeout is still clean, we can skip waiting for it (if we're part of a data integrity sync, we'll be waiting for all writeout pages afterwards, so we'll still be waiting for the other guy's write that's cleaned the page). Signed-off-by: Nick Piggin Cc: Chris Mason Cc: Dave Chinner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page-writeback.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index c3fb38b1ea43..2e8c2b01d5d5 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -945,11 +945,20 @@ continue_unlock: goto continue_unlock; } - if (wbc->sync_mode != WB_SYNC_NONE) - wait_on_page_writeback(page); + if (!PageDirty(page)) { + /* someone wrote it for us */ + goto continue_unlock; + } + + if (PageWriteback(page)) { + if (wbc->sync_mode != WB_SYNC_NONE) + wait_on_page_writeback(page); + else + goto continue_unlock; + } - if (PageWriteback(page) || - !clear_page_dirty_for_io(page)) + BUG_ON(PageWriteback(page)); + if (!clear_page_dirty_for_io(page)) goto continue_unlock; ret = (*writepage)(page, wbc, data); -- 2.20.1