linux-kernel - [PATCH 2/2] f2fs: avoid an overflow during utilization calculation

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Date:	Tue, 03 Sep 2013 15:27:53 +0900
From:	Jaegeuk Kim <jaegeuk.kim@...sung.com>
To:	unlisted-recipients:; (no To-header on input)
Cc:	Jaegeuk Kim <jaegeuk.kim@...sung.com>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net
Subject: [PATCH 2/2] f2fs: avoid an overflow during utilization calculation

The current f2fs uses all the block counts with 32 bit numbers, which is able to
cover about 15TB volume.

But in calculation of utilization, f2fs multiplies the count by 100 which can
induce overflow.
This patch fixes this.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@...sung.com>
---
 fs/f2fs/segment.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index cd9bd93..e0d6d3a 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -471,7 +471,7 @@ static inline bool has_not_enough_free_secs(struct f2fs_sb_info *sbi, int freed)
 
 static inline int utilization(struct f2fs_sb_info *sbi)
 {
-	return div_u64(valid_user_blocks(sbi) * 100, sbi->user_block_count);
+	return div_u64((u64)valid_user_blocks(sbi) * 100, sbi->user_block_count);
 }
 
 /*
-- 
1.8.3.1.437.g0dbd812

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