linux-ext4 - [PATCH] ext4: fix freespace accounting with mballoc on 32bit machines

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Message-ID: <4720F7A6.9060905@redhat.com>
Date:	Thu, 25 Oct 2007 15:08:06 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	ext4 development <linux-ext4@...r.kernel.org>
CC:	Alex Tomas <alex@...sterfs.com>, Mingming Cao <cmm@...ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH] ext4: fix freespace accounting with mballoc on 32bit machines

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>

--- linux.orig/fs/ext4/mballoc.c	2007-10-25 14:47:25.048435451 -0500
+++ linux/fs/ext4/mballoc.c	2007-10-25 14:47:35.815160682 -0500
@@ -3005,7 +3005,7 @@
 				- 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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