linux-kernel - Re: [Regression] 2.6.38 ncpfs

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Message-ID: <BANLkTin=xwfr5aVhzyL_FFo3K3SNMW9OQw@mail.gmail.com>
Date:	Thu, 14 Apr 2011 10:29:34 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Bongani Hlope <bonganilinux@...b.co.za>
Cc:	npiggin@...nel.dk, "Rafael J. Wysocki" <rjw@...k.pl>,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	Greg KH <greg@...ah.com>,
	"Dr. Bernd Feige" <bernd.feige@...klinik-freiburg.de>,
	Petr Vandrovec <petr@...drovec.name>,
	Arnd Bergmann <arnd@...db.de>, Christoph Hellwig <hch@....de>
Subject: Re: [Regression] 2.6.38 ncpfs

On Thu, Apr 14, 2011 at 10:14 AM, Bongani Hlope <bonganilinux@...b.co.za> wrote:
>
> The bug is caused by commit fb2d5b86aff355a27ebfc132d3c99f4a940cc3fe, which
> was committed by Nick. Can you please either revert Nick's changes or include
> the attached patch (or a better version, because I'm not that clued up with
> ncpfs).

Hmm. Your patch isn't correct. You can't just do

   if (!mutex_is_locked(&dentry->d_inode->i_mutex)) {
      mutex_lock(&inode->i_mutex);

because code like that makes no sense - maybe it was locked by
somebody _else_, and you would need to lock it.

That said, I do think that the

  BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));

is wrong, since even the comment above it talks about the _parent_
dentry, not the dentry that is actually being modified.

So there's clearly a bug somewhere, and the fix may be to just remove
that BUG_ON().

Added some more people to the cc.

                                   Linus
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