linux-ext4 - Re: [PATCH] jbd2: fix wrong use of do

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Date:	Mon, 12 Jan 2009 02:44:40 +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: Re: [PATCH] jbd2: fix wrong use of do_div

[I got a simpler version 2 of the patch here]

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!

Fix it by using div_u64 instead.

Signed-off-by: Simon Holm Thøgersen <odie@...aau.dk>
---
 fs/jbd2/journal.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 5667530..eb34300 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -37,10 +37,10 @@
 #include <linux/proc_fs.h>
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
+#include <linux/math64.h>
 
 #include <asm/uaccess.h>
 #include <asm/page.h>
-#include <asm/div64.h>
 
 EXPORT_SYMBOL(jbd2_journal_start);
 EXPORT_SYMBOL(jbd2_journal_restart);
@@ -846,8 +846,8 @@ 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));
+	seq_printf(seq, "  %lluus average transaction commit time\n",
+		   div_u64(s->journal->j_average_commit_time, 1000));
 	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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