[Devel] [PATCH rh7] mm: writeback: do not check dirty limits for ub0

[Vladimir Davydov]

It's just a waste of time, because ub0 has no ub-specific dirty limits.
balance_dirty_pages handles ub0 case anyway.

Signed-off-by: Vladimir Davydov <vdavydov at virtuozzo.com>
---
 mm/page-writeback.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 9940d5fe7dcb..ba5f93a84fca 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1403,9 +1403,11 @@ static void balance_dirty_pages_ub(struct address_space *mapping,
 	unsigned long pages_written = 0;
 	unsigned long pause = 1;
 	struct user_beancounter *ub = get_io_ub();
-
 	struct backing_dev_info *bdi = mapping->backing_dev_info;
 
+	if (ub == get_ub0())
+		return;
+
 	for (;;) {
 		unsigned long nr_to_write = write_chunk - pages_written;
 
-- 
2.1.4