linux-kernel - [PATCH] jbd2: fix wrong use of do

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Message-Id: <1231701393.17759.30.camel@odie.local>
Date:	Sun, 11 Jan 2009 20:16:33 +0100
From:	Simon Holm Thøgersen <odie@...aau.dk>
To:	Theodore Tso <tytso@....edu>
Cc:	linux-ext4 <linux-ext4@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Randy Dunlap <randy.dunlap@...cle.com>
Subject: [PATCH] jbd2: fix wrong use of do_div

the following warning:

fs/jbd2/journal.c: In function ‘jbd2_seq_info_show’:
fs/jbd2/journal.c:850: warning: format ‘%lu’ expects type ‘long
unsigned int’, but argument 3 has type ‘uint32_t’

is caused by wrong usage of do_div that modifies the dividend in-place
and returns the quotient. So not only would an incorrect value be
displayed, but s->journal->j_average_commit_time would also be changed
to a wrong value! This patch fixes it.

Signed-off-by: Simon Holm Thøgersen <odie@...aau.dk>
---
 fs/jbd2/journal.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 5667530..f9620e3 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -828,6 +828,7 @@ static void *jbd2_seq_info_next(struct seq_file *seq, void *v, loff_t *pos)
 static int jbd2_seq_info_show(struct seq_file *seq, void *v)
 {
 	struct jbd2_stats_proc_session *s = seq->private;
+	u64 n;
 
 	if (v != SEQ_START_TOKEN)
 		return 0;
@@ -846,8 +847,11 @@ static int jbd2_seq_info_show(struct seq_file *seq, void *v)
 	    jiffies_to_msecs(s->stats->u.run.rs_flushing / s->stats->ts_tid));
 	seq_printf(seq, "  %ums logging transaction\n",
 	    jiffies_to_msecs(s->stats->u.run.rs_logging / s->stats->ts_tid));
-	seq_printf(seq, "  %luus average transaction commit time\n",
-		   do_div(s->journal->j_average_commit_time, 1000));
+
+	n = s->journal->j_average_commit_time;
+	do_div(n, 1000);
+	seq_printf(seq, "  %llus average transaction commit time\n", n);
+
 	seq_printf(seq, "  %lu handles per transaction\n",
 	    s->stats->u.run.rs_handle_count / s->stats->ts_tid);
 	seq_printf(seq, "  %lu blocks per transaction\n",
-- 
1.6.0.2.526.g5c283

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