2007-11-29 20:54:08

by Andrew Morton

[permalink] [raw]
Subject: [patch 4/8] ext4: fix freespace accounting with mballoc on 32bit machines

From: Eric Sandeen <[email protected]>

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

[root@bear-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 <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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)