[PATCH 8/8] blk-throttle: enable throttling of task while dirtying pages

[Vivek Goyal <vgoyal@redhat.com>]

Put the blk_throtl_dirty_pages() hook in
balance_dirty_pages_ratelimited_nr() to enable task throttling.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 include/linux/blkdev.h |    5 +++++
 mm/page-writeback.c    |    3 +++
 2 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 4ce6e68..5d4a57e 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1180,12 +1180,17 @@ static inline uint64_t rq_io_start_time_ns(struct request *req)
 extern int blk_throtl_init(struct request_queue *q);
 extern void blk_throtl_exit(struct request_queue *q);
 extern int blk_throtl_bio(struct request_queue *q, struct bio **bio);
+extern void blk_throtl_dirty_pages(struct address_space *mapping,
+				unsigned long nr_dirty);
 #else /* CONFIG_BLK_DEV_THROTTLING */
 static inline int blk_throtl_bio(struct request_queue *q, struct bio **bio)
 {
 	return 0;
 }
 
+static inline void blk_throtl_dirty_pages(struct address_space *mapping,
+				unsigned long nr_dirty) {}
+
 static inline int blk_throtl_init(struct request_queue *q) { return 0; }
 static inline int blk_throtl_exit(struct request_queue *q) { return 0; }
 #endif /* CONFIG_BLK_DEV_THROTTLING */
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 31f6988..943e551 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -629,6 +629,9 @@ void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 	unsigned long ratelimit;
 	unsigned long *p;
 
+	/* Subject writes to IO controller throttling */
+	blk_throtl_dirty_pages(mapping, nr_pages_dirtied);
+
 	ratelimit = ratelimit_pages;
 	if (mapping->backing_dev_info->dirty_exceeded)
 		ratelimit = 8;
-- 
1.7.4.4