linux-ext4 - [patch 4/8] ext4: fix freespace accounting with mballoc on 32bit machines

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Message-Id: <200711292052.lATKqouX006834@imap1.linux-foundation.org>
Date:	Thu, 29 Nov 2007 12:52:50 -0800
From:	akpm@...ux-foundation.org
To:	cmm@...ibm.com
Cc:	tytso@....edu, linux-ext4@...r.kernel.org,
	akpm@...ux-foundation.org, sandeen@...hat.com
Subject: [patch 4/8] ext4: fix freespace accounting with mballoc on 32bit machines

From: Eric Sandeen <sandeen@...hat.com>

On a 32bit machine, passing the negative unsigned long fe_len
into percpu_counter_add (which expects s64) messes up the counters:

[root@...r-05 linux-2.6.23-rc7]# df -h

Filesystem            Size  Used Avail Use% Mounted on
/dev/sdb7              97G -149P  149P   -  /mnt/test

Patch below fixes this.

Signed-off-by: Eric Sandeen <sandeen@...hat.com>
Cc: <linux-ext4@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---

 fs/ext4/mballoc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff -puN fs/ext4/mballoc.c~ext4-fix-freespace-accounting-with-mballoc-on-32bit-machines fs/ext4/mballoc.c
--- a/fs/ext4/mballoc.c~ext4-fix-freespace-accounting-with-mballoc-on-32bit-machines
+++ a/fs/ext4/mballoc.c
@@ -3005,7 +3005,7 @@ static int ext4_mb_mark_diskspace_used(s
 				- ac->ac_b_ex.fe_len);
 	gdp->bg_checksum = ext4_group_desc_csum(sbi, ac->ac_b_ex.fe_group, gdp);
 	spin_unlock(sb_bgl_lock(sbi, ac->ac_b_ex.fe_group));
-	percpu_counter_add(&sbi->s_freeblocks_counter, - ac->ac_b_ex.fe_len);
+	percpu_counter_sub(&sbi->s_freeblocks_counter, ac->ac_b_ex.fe_len);
 
 	err = ext4_journal_dirty_metadata(handle, bitmap_bh);
 	if (err)
_
-
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