From: Chao Yu <chao2.yu@samsung.com>
Date: Wed, 23 Sep 2015 01:25:43 +0000 (+0800)
Subject: f2fs: fix incorrect bimodal calculation
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=1d7e10d58a1f62c8c44668cca1cff6a2dd57d7d9;p=deliverable%2Flinux.git

f2fs: fix incorrect bimodal calculation

In update_sit_info, we use div_u64 to handle 'u64 divide u64' case, but
div_u64 can only handle 32-bits divisor, so our divisor with u64 type
passed to div_u64 will overflow, result in the wrong calculation when
show debug info of f2fs as below:

BDF: 464, avg. vblocks: 23509
(BDF should never exceed 100)

So change to use div64_u64 to handle this case correctly.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---

diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
index ebfcc4039057..615a307a7871 100644
--- a/fs/f2fs/debug.c
+++ b/fs/f2fs/debug.c
@@ -118,7 +118,7 @@ static void update_sit_info(struct f2fs_sb_info *sbi)
 		}
 	}
 	dist = div_u64(MAIN_SECS(sbi) * hblks_per_sec * hblks_per_sec, 100);
-	si->bimodal = div_u64(bimodal, dist);
+	si->bimodal = div64_u64(bimodal, dist);
 	if (si->dirty_count)
 		si->avg_vblocks = div_u64(total_vblocks, ndirty);
 	else