linux-kernel - [PATCH] fs: gfs2: rgrp: Use u64 instead of s64 for statistic and square variables in gfs2_rgrp

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Date:	Tue, 21 Jul 2015 05:26:40 +0800
From:	Chen Gang <xili_gchen_5257@...mail.com>
To:	swhiteho@...hat.com
CC:	cluster-devel@...hat.com,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH] fs: gfs2: rgrp: Use u64 instead of s64 for statistic and
 square variables in gfs2_rgrp_congested()

l_srttb, a_srttb ...  are statistic variables which should be always
unsigned, and sqr_diff is a square variable, which is always unsigned,
too.

Also sqr_diff is renamed to square_diff which is more preciser.

The related warning (with allmodconfig under cris for next-20150720):

    CC [M]  fs/gfs2/rgrp.o
  In file included from arch/cris/include/generated/asm/div64.h:1:0,
                   from include/linux/kernel.h:137,
                   from include/linux/list.h:8,
                   from include/linux/preempt.h:10,
                   from include/linux/spinlock.h:50,
                   from include/linux/mmzone.h:7,
                   from include/linux/gfp.h:5,
                   from include/linux/slab.h:14,
                   from fs/gfs2/rgrp.c:12:
  fs/gfs2/rgrp.c: In function 'gfs2_rgrp_congested':
  include/asm-generic/div64.h:43:28: warning: comparison of distinct pointer types lacks a cast
    (void)(((typeof((n)) *)0) == ((uint64_t *)0)); \
                              ^
  fs/gfs2/rgrp.c:1882:3: note: in expansion of macro 'do_div'
     do_div(a_srttb, nonzero);
     ^

Signed-off-by: Chen Gang <gang.chen.5i5j@...il.com>
---
 fs/gfs2/rgrp.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index c92ae7fd..08e47a0 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -1862,11 +1862,11 @@ static bool gfs2_rgrp_congested(const struct gfs2_rgrpd *rgd, int loops)
 	const struct gfs2_glock *gl = rgd->rd_gl;
 	const struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 	struct gfs2_lkstats *st;
-	s64 r_dcount, l_dcount;
-	s64 l_srttb, a_srttb = 0;
+	u64 r_dcount, l_dcount;
+	u64 l_srttb, a_srttb = 0;
 	s64 srttb_diff;
-	s64 sqr_diff;
-	s64 var;
+	u64 square_diff;
+	u64 var;
 	int cpu, nonzero = 0;
 
 	preempt_disable();
@@ -1892,7 +1892,7 @@ static bool gfs2_rgrp_congested(const struct gfs2_rgrpd *rgd, int loops)
 		return false;
 
 	srttb_diff = a_srttb - l_srttb;
-	sqr_diff = srttb_diff * srttb_diff;
+	square_diff = srttb_diff * srttb_diff;
 
 	var *= 2;
 	if (l_dcount < 8 || r_dcount < 8)
@@ -1900,7 +1900,7 @@ static bool gfs2_rgrp_congested(const struct gfs2_rgrpd *rgd, int loops)
 	if (loops == 1)
 		var *= 2;
 
-	return ((srttb_diff < 0) && (sqr_diff > var));
+	return ((srttb_diff < 0) && (square_diff > var));
 }
 
 /**
-- 
1.9.3
--
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