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From: Dave Hansen <haveblue@us.ibm.com>
To: Jan Blunck <jblunck@suse.de>
Cc: Linux-Kernel Mailinglist <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@osdl.org>, Christoph Hellwig <hch@lst.de>
Subject: Re: [patch 2/2] r/o bind mounts: Accept passing a mnt NULL pointer to mnt_drop_write()
Date: Fri, 12 Oct 2007 09:10:11 -0700	[thread overview]
Message-ID: <1192205411.20859.52.camel@localhost> (raw)
In-Reply-To: <20071012155020.197228145@hasse.suse.de>

On Fri, 2007-10-12 at 17:50 +0200, Jan Blunck wrote:
> In case of somebody opens a file with dentry_open(dentry, NULL, ...) we don't
> want to stumble on the NULL pointer mnt in struct file. 
...
> +++ b/fs/namespace.c
> @@ -253,6 +253,9 @@ void mnt_drop_write(struct vfsmount *mnt
>         int must_check_underflow = 0;
>         struct mnt_writer *cpu_writer;
> 
> +       if (!mnt)
> +               return;

I kinda wish we'd fix these in the callers.  I know we do something
similar to this with mntput(), but I worry a bit that this just
discourages people from using the right interfaces.

Do you have a case where we're actually getting a NULL mount in here?
We had at least one in reiser4 that really revealed some nastiness in
the fs that needed fixing.

-- Dave


  reply	other threads:[~2007-10-12 16:33 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-10-12 15:50 [patch 0/2] r/o bind mount fixes for 2.6.23-mm1 Jan Blunck
2007-10-12 15:50 ` [patch 1/2] r/o bind mounts: Dont touch the vfsmount after path_put() Jan Blunck
2007-10-12 16:06   ` Dave Hansen
2007-10-12 15:50 ` [patch 2/2] r/o bind mounts: Accept passing a mnt NULL pointer to mnt_drop_write() Jan Blunck
2007-10-12 16:10   ` Dave Hansen [this message]
2007-10-13 11:25   ` Christoph Hellwig

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