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authorNick Piggin <npiggin@suse.de>2009-01-06 14:39:10 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-06 15:58:59 -0800
commit515f4a037fb9ab736f8bad733fcd2ffd350cf265 (patch)
tree0862eee6405297ef23a5b3d8906cfef5783c0c77
parent5a3d5c9813db56a75934eb1015367fda23a8b0b4 (diff)
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 <npiggin@suse.de> Cc: Chris Mason <chris.mason@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/page-writeback.c17
1 files 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);