linux-ext4 - Re: [PATCH 1/1] Null Pointer when make_indexed

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Message-ID: <BANLkTinv=c+mXvnirHtCzfuk0eK913dVtQ@mail.gmail.com>
Date:	Mon, 9 May 2011 19:33:19 +0800
From:	Yongqiang Yang <xiaoqiangnk@...il.com>
To:	Jan Kara <jack@...e.cz>
Cc:	Allison Henderson <achender@...ux.vnet.ibm.com>,
	Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH 1/1] Null Pointer when make_indexed_dir returns -ENOSPC

On Mon, May 9, 2011 at 7:30 PM, Jan Kara <jack@...e.cz> wrote:
> On Mon 09-05-11 19:18:37, Yongqiang Yang wrote:
>> On Mon, May 9, 2011 at 7:03 PM, Jan Kara <jack@...e.cz> wrote:
>> > On Sat 07-05-11 16:54:27, Allison Henderson wrote:
>> >> Fix for a null pointer bug found while running punch hole tests
>> >>
>> >> Signed-off-by: Allison Henderson <achender@...ibm.com>
>> >> ---
>> >> :100644 100644 3c7a06e... 3302a6c... M        fs/ext4/namei.c
>> >>  fs/ext4/namei.c |    3 ++-
>> >>  1 files changed, 2 insertions(+), 1 deletions(-)
>> >>
>> >> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
>> >> index 3c7a06e..3302a6c 100644
>> >> --- a/fs/ext4/namei.c
>> >> +++ b/fs/ext4/namei.c
>> >> @@ -1422,7 +1422,8 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry,
>> >>                */
>> >>               ext4_mark_inode_dirty(handle, dir);
>> >>               ext4_handle_dirty_metadata(handle, dir, frame->bh);
>> >> -             ext4_handle_dirty_metadata(handle, dir, bh);
>> >> +             if (bh)
>> >> +                     ext4_handle_dirty_metadata(handle, dir, bh);
>> >  I'm puzzled - bh here is bh2 from the beginning of the function and we
>> > check it for being NULL after we ext4_append() it. So how can this happen?
>> do_split() encounters a journal error and set bh to NULL before returning.
> Ah, I see. But then you just reintroduced the bug I was trying to fix. So
> either do_split() has to do the marking of buffer dirty, or we have to do
> it before calllig do_split(), or do_split() has to be changed and not
> release passed buffer (and the two callers have to do it - which they seem
> to do anyway). I don't mind either way but your fix is wrong.
The fix is made by Allison not me, I think Allison will have a look at
the thread.

Yongqiang.
>
>                                                                Honza
> --
> Jan Kara <jack@...e.cz>
> SUSE Labs, CR
>



-- 
Best Wishes
Yongqiang Yang
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