Add balance_dirty_pages_ratelimited() to cont_expand_zero()

On the systems, ftruncate() which expand size for FAT became the cause
of OOM.  The cont_expand_zero() filled all memory with dirty pages,
and since disk is very slow, limit of page scanning was exceeded, then
it triggered OOM.

This adds balance_dirty_pages_ratelimited() to avoid filling memory
with dirty pages.

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index 7d51e649b19a..3db4a26adc44 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2246,6 +2246,8 @@ int cont_expand_zero(struct file *file, struct address_space *mapping,
                         goto out;
                 BUG_ON(err != len);
                 err = 0;
+
+                balance_dirty_pages_ratelimited(mapping);
         }
 
         /* page covers the boundary, find the boundary offset */