From: Jan Kara <jack@suse.cz>
To: Ted Ts'o <tytso@mit.edu>
Cc: Jan Kara <jack@suse.cz>, Yongqiang Yang <xiaoqiangnk@gmail.com>,
Allison Henderson <achender@linux.vnet.ibm.com>,
Ext4 Developers List <linux-ext4@vger.kernel.org>
Subject: Re: [PATCH 1/1] Null Pointer when make_indexed_dir returns -ENOSPC
Date: Mon, 9 May 2011 16:05:37 +0200 [thread overview]
Message-ID: <20110509140537.GN4122@quack.suse.cz> (raw)
In-Reply-To: <20110509135516.GJ4138@thunk.org>
On Mon 09-05-11 09:55:16, Ted Tso wrote:
> On Mon, May 09, 2011 at 01:30:52PM +0200, Jan Kara wrote:
> > 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.
>
> I think it's OK. We do call ext4_handle_dirty_metadata on frame->bh,
> which deals with the original version of bh. And the cases where
> do_split() sets bh to NULL is either (a) a journal error, in which
> case we will have already aborted the journal, or an I/O error while
> reading in the block, so bh won't have gotten modified yet.
>
> Is there a case that you're worried about that I'm missing?
Yes. ext4_append() can return ENOSPC and passed bh will get set to NULL
without being marked dirty. Note that we need to call
ext4_handle_dirty_metadata() on the passed bh as well specifically in the
make_indexed_dir() case because there we move contents of the first block
(in frame->bh) to the second block (passed bh) and create indexed tree root
in the first block. Then we call do_split() to further split the second
block...
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
next prev parent reply other threads:[~2011-05-09 14:05 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-07 23:54 [PATCH 1/1] Null Pointer when make_indexed_dir returns -ENOSPC Allison Henderson
2011-05-09 0:38 ` Ted Ts'o
2011-05-09 11:03 ` Jan Kara
2011-05-09 11:18 ` Yongqiang Yang
2011-05-09 11:20 ` Yongqiang Yang
2011-05-09 11:21 ` Yongqiang Yang
2011-05-09 11:30 ` Jan Kara
2011-05-09 11:33 ` Yongqiang Yang
2011-05-09 11:36 ` Jan Kara
2011-05-09 13:55 ` Ted Ts'o
2011-05-09 14:05 ` Jan Kara [this message]
2011-05-09 14:22 ` Ted Ts'o
2011-05-09 14:27 ` [PATCH -v2] ext4: don't dereference null pointer when make_indexed_dir() fails Theodore Ts'o
2011-05-09 14:56 ` Eric Sandeen
2011-05-09 14:42 ` [PATCH 1/1] Null Pointer when make_indexed_dir returns -ENOSPC Jan Kara
2011-05-09 20:39 ` Allison Henderson
2011-05-10 13:34 ` Jan Kara
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