linux-ext4 - Re: [PATCH] ext4_freeze: don't return to userspace with a mutex held

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Date:	Sun, 4 Apr 2010 16:52:37 -0400
From:	tytso@....edu
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] ext4_freeze: don't return to userspace with a mutex
 held

On Mon, Mar 29, 2010 at 05:34:43PM -0500, Eric Sandeen wrote:
> 
> I don't -think- we need to do this; by now we should have s_frozen
> set, and nobody else should be coming down the pipe to get to
> the journal.  However, just to be on the safe side, I added
> a couple of vfs_check_frozen() calls in ext4 functions which will
> arrive at start_this_handle(), which should ensure that we never
> get any journal traffic generated while frozen.

Um, I think the addition of vfs_check_frozen(), esp. to
ext4_journal_start_sb() is absolutely necessary.  What else do we have
to prevent filesystem modifications from going to the file systme
layer?  I didn't see anything in the VFS layer that checks s_frozen;
am I missing something?

					- Ted
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