On Fri, Oct 28, 2011 at 07:24:06AM +0200, Greg KH wrote:
> On Fri, Oct 28, 2011 at 10:36:08AM +0800, Zheng Liu wrote:
> > On Thu, Oct 27, 2011 at 01:53:22PM +0200, Greg KH wrote:
> > > On Thu, Oct 27, 2011 at 05:43:29AM -0400, Ted Ts'o wrote:
> > > > On Wed, Sep 28, 2011 at 06:45:03PM +0800, Tao Ma wrote:
> > > > > actually this bug does show up in 2.6.39 and I think stable tree still
> > > > > needs this fix. After some careful test, my colleague has generated
> > > > > the patch. Please considering ack it so that Greg can add it into the
> > > > > stable tree.
> > > >
> > > > Sorry for the delay, but yes. This patch would be good for the stable
> > > > tree for 2.6.39 (if Greg is still accepting patches for
> > > > 2.6.39-stable). It doesn't apply for upstream ext4 since the code has
> > > > been changed/refactored since then, but it's a good fix.
> > >
> > > No, .39 has not been maintained for quite some time now, sorry.
> > Hi Greg,
> >
> > Thank you for your attention. Actually this bug is between from .32 to
> > .39. Please considering to apply this patch to other stable or longterm
> > trees.
>
> Ah, ok, that makes sense, can you provide me a patch that will apply to
> the .32 and .33-longterm kernels?
Hi Greg,
I couldn't download the .32 and .33-longterm kernels from kernel.org
because the full sources were not found on that server. Thus this patch
is generated from the .32-mainline kernel and can be applied to the .32
and .33 kernels.
regards,
Zheng
>From ff98f00676657b797c426c80804a3fde3f86ea83 Mon Sep 17 00:00:00 2001
From: Zheng Liu <wenqing.lz@xxxxxxxxxx>
Date: Fri, 28 Oct 2011 15:08:30 +0800
Subject: [PATCH] ext4: fix BUG_ON() in ext4_ext_insert_extent()
We will meet with a BUG_ON() if following script is run.
mkfs.ext4 -b 4096 /dev/sdb1 1000000
mount -t ext4 /dev/sdb1 /mnt/sdb1
fallocate -l 100M /mnt/sdb1/test
sync
for((i=0;i<170;i++))
do
dd if=/dev/zero of=/mnt/sdb1/test conv=notrunc bs=256k count=1
seek=`expr $i \* 2`
done
umount /mnt/sdb1
mount -t ext4 /dev/sdb1 /mnt/sdb1
dd if=/dev/zero of=/mnt/sdb1/test conv=notrunc bs=256k count=1 seek=341
umount /mnt/sdb1
mount /dev/sdb1 /mnt/sdb1
dd if=/dev/zero of=/mnt/sdb1/test conv=notrunc bs=256k count=1 seek=340
sync
The reason is that it forgot to mark dirty when splitting two extents in
ext4_ext_convert_to_initialized(). Althrough ex has been updated in
memory, it is not dirtied both in ext4_ext_convert_to_initialized() and
ext4_ext_insert_extent(). The disk layout is corrupted. Then it will
meet with a BUG_ON() when writting at the start of that extent again.
Cc: stable@xxxxxxxxxx #for 2.6.39
Cc: Greg Kroah-Hartman <greg@xxxxxxxxx>
Cc: "Theodore Ts'o" <tytso@xxxxxxx>
Cc: Xiaoyun Mao <xiaoyun.maoxy@xxxxxxxxxxxxxx>
Cc: Yingbin Wang <yingbin.wangyb@xxxxxxxxxxxxxx>
Cc: Jia Wan <jia.wanj@xxxxxxxxxxxxxx>
Signed-off-by: Zheng Liu <wenqing.lz@xxxxxxxxxx>
---
fs/ext4/extents.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 715264b..ab6fa35 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2555,6 +2555,7 @@ static int
ext4_ext_convert_to_initialized(handle_t *handle,
ex1 = ex;
ex1->ee_len = cpu_to_le16(iblock - ee_block);
ext4_ext_mark_uninitialized(ex1);
+ ext4_ext_dirty(handle, inode, path + depth);
ex2 = &newex;
}
/*
--
1.7.4.1
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