[PATCH 7/9] Add balance_dirty_pages_ratelimited() to cont_expand_zero()

[OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>]

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>
---

 fs/buffer.c |    2 ++
 1 file changed, 2 insertions(+)

diff -puN fs/buffer.c~cont_expand_zero-fix fs/buffer.c
--- linux-2.6/fs/buffer.c~cont_expand_zero-fix	2008-04-05 18:22:57.000000000 +0900
+++ linux-2.6-hirofumi/fs/buffer.c	2008-04-05 18:22:57.000000000 +0900
@@ -2251,6 +2251,8 @@ int cont_expand_zero(struct file *file, 
 			goto out;
 		BUG_ON(err != len);
 		err = 0;
+
+		balance_dirty_pages_ratelimited(mapping);
 	}
 
 	/* page covers the boundary, find the boundary offset */
_