linux-kernel - Re: missing mnt_drop

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Date:	Wed, 26 Sep 2007 09:19:05 -0700
From:	Dave Hansen <haveblue@...ibm.com>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	hch <hch@...radead.org>
Subject: Re: missing mnt_drop_write() on open error

On Wed, 2007-09-26 at 10:38 +0200, Miklos Szeredi wrote:
> In __dentry_open() there's still a few places where fput() won't be
> called, notably when ->open fails, which is what I'm triggering I
> think.
> 
> Also even more horrible things can happen because of the
> nd->intent.open.file thing.  For example if the lookup routine calls
> lookup_instantiate_filp(), and after this, but before may_open() some
> error happens, then release_open_intent() will call fput() on the
> file, which will cause mnt_drop_write() to be called, even though a
> matching mnt_want_write() hasn't yet been called.  Ugly, eh? 

I'm not sure it is _that_ horrible. ;)

Do you see any reason we can't just shadow the
get/put_write_access(inode) calls with mnt_want/drop_write() calls?  I
think they're always matched.

-- Dave

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