From 96f9945614ceaa6142e07516ad5925f9837f191e Mon Sep 17 00:00:00 2001
From: Chao Yu <yuchao0@huawei.com>
Date: Mon, 22 Oct 2018 09:12:51 +0800
Subject: [PATCH] f2fs: fix to account IO correctly

BugLink: https://bugs.launchpad.net/bugs/1836802

commit 4c58ed076875f36dae0f240da1e25e99e5d4afb8 upstream.

Below race can cause reversed reference on dirty count, fix it by
relocating __submit_bio() and inc_page_count().

Thread A				Thread B
- f2fs_inplace_write_data
 - f2fs_submit_page_bio
  - __submit_bio
					- f2fs_write_end_io
					 - dec_page_count
  - inc_page_count

Cc: <stable@vger.kernel.org>
Fixes: d1b3e72d5490 ("f2fs: submit bio of in-place-update pages")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
---
 fs/f2fs/data.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index f24d7b8858ed..1ca00f0bd261 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -381,10 +381,10 @@ int f2fs_submit_page_bio(struct f2fs_io_info *fio)
 	}
 	bio_set_op_attrs(bio, fio->op, fio->op_flags);
 
-	__submit_bio(fio->sbi, bio, fio->type);
-
 	if (!is_read_io(fio->op))
 		inc_page_count(fio->sbi, WB_DATA_TYPE(fio->page));
+
+	__submit_bio(fio->sbi, bio, fio->type);
 	return 0;
 }
 
-- 
2.39.2