linux-ext4 - Re: [PATCH] ext4: fix race condition when loading block or inode bitmaps

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Message-ID: <20111125161942.GF5167@thunk.org>
Date:	Fri, 25 Nov 2011 11:19:42 -0500
From:	Ted Ts'o <tytso@....edu>
To:	Tao Ma <tm@....ma>
Cc:	Ext4 Developers List <linux-ext4@...r.kernel.org>,
	stable@...nel.org
Subject: Re: [PATCH] ext4: fix race condition when loading block or inode
 bitmaps

On Fri, Nov 25, 2011 at 10:34:54AM +0800, Tao Ma wrote:
> Sorry, but I don't get your meaning here.
> In bitmap_uptodate, we check both the flag of BH_uptodate and
> BH_BITMAP_UPTODATE. And in your patch below, we just move the set of
> bitmap_uptodate after bh_uptodate. So I don't think the above scenario
> would ever happen. Could you please explain it in more detail?

Yes, you're right.  I didn't realize bitmap_uptodate() checked both
bits.  I had assumed it used the same convention as the other
functions that set/git bits in bh_state.

Rats, and I thought I had finally nailed the bug...

						- Ted
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