[PATCH 3.15 2/2] f2fs: check bdi->dirty_exceeded when trying to skip data writes

[Jaegeuk Kim <jaegeuk@kernel.org>]

commit dd6b9bf5883c3ca9c17bac80ccd8615fe5a452a3 upstream.

If we don't check the current backing device status, balance_dirty_pages can
fall into infinite pausing routine.

This can be occurred when a lot of directories make a small number of dirty
dentry pages including files.

Reported-by: Brian Chadwick <brianchad@westnet.com.au>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/f2fs/node.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index a9c0495..5696bde 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -42,6 +42,8 @@ bool available_free_memory(struct f2fs_sb_info *sbi, int type)
 		mem_size = (nm_i->nat_cnt * sizeof(struct nat_entry)) >> 12;
 		res = mem_size < ((val.totalram * nm_i->ram_thresh / 100) >> 2);
 	} else if (type == DIRTY_DENTS) {
+		if (sbi->sb->s_bdi->dirty_exceeded)
+			return false;
 		mem_size = get_pages(sbi, F2FS_DIRTY_DENTS);
 		res = mem_size < ((val.totalram * nm_i->ram_thresh / 100) >> 1);
 	}
-- 
2.0.1.472.g6f92e5f