linux-kernel - [PATCH] f2fs: fix to account IO correctly

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Date:   Wed, 17 Oct 2018 17:49:54 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     <jaegeuk@...nel.org>
CC:     <linux-f2fs-devel@...ts.sourceforge.net>,
        <linux-kernel@...r.kernel.org>, <chao@...nel.org>,
        Chao Yu <yuchao0@...wei.com>
Subject: [PATCH] f2fs: fix to account IO correctly

Below race can cause reversed reference on F2FS_RD_DATA, there is
the same issue in f2fs_submit_page_bio(), fix them by relocate
__submit_bio() and inc_page_count.

Thread A			Thread B
- f2fs_write_begin
 - f2fs_submit_page_read
 - __submit_bio
				- f2fs_read_end_io
				 - __read_end_io
				 - dec_page_count(, F2FS_RD_DATA)
 - inc_page_count(, F2FS_RD_DATA)

Signed-off-by: Chao Yu <yuchao0@...wei.com>
---
 fs/f2fs/data.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index c03bd0c2ed22..8b9240762156 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -480,10 +480,10 @@ 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);
-
 	inc_page_count(fio->sbi, is_read_io(fio->op) ?
 			__read_io_type(page): WB_DATA_TYPE(fio->page));
+
+	__submit_bio(fio->sbi, bio, fio->type);
 	return 0;
 }
 
@@ -612,8 +612,8 @@ static int f2fs_submit_page_read(struct inode *inode, struct page *page,
 		return -EFAULT;
 	}
 	ClearPageError(page);
-	__submit_bio(F2FS_I_SB(inode), bio, DATA);
 	inc_page_count(F2FS_I_SB(inode), F2FS_RD_DATA);
+	__submit_bio(F2FS_I_SB(inode), bio, DATA);
 	return 0;
 }
 
-- 
2.18.0.rc1