[PATCH 1/8] buffer: make invalidate_bdev() drain all percpu LRU add caches

[Tejun Heo <tj@kernel.org>]

invalidate_bdev() should release all page cache pages which are clean
and not being used; however, if some pages are still in the percpu LRU
add caches on other cpus, those pages are considered in used and don't
get released.  Fix it by calling lru_add_drain_all() before trying to
invalidate pages.

This problem was discovered while testing block automatic native
capacity unlocking.  Null pages which were read before automatic
unlocking didn't get released by invalidate_bdev() and ended up
interfering with partition scan after unlocking.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 fs/buffer.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index c9c266d..08e422d 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -275,6 +275,7 @@ void invalidate_bdev(struct block_device *bdev)
 		return;
 
 	invalidate_bh_lrus();
+	lru_add_drain_all();	/* make sure all lru add caches are flushed */
 	invalidate_mapping_pages(mapping, 0, -1);
 }
 EXPORT_SYMBOL(invalidate_bdev);
-- 
1.6.4.2