linux-kernel - Re: [PATCH 2/2] Fix possible leakage of blocks in UDF

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Date:	Fri, 1 Jun 2007 23:10:36 +0200
From:	Jan Kara <jack@...e.cz>
To:	Eric Sandeen <sandeen@...deen.net>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Cyrill Gorcunov <gorcunov@...il.com>
Subject: Re: [PATCH 2/2] Fix possible leakage of blocks in UDF

On Wed 30-05-07 16:46:28, Eric Sandeen wrote:
> Jan Kara wrote:
> >   Hello,
> > 
> > On Thu 24-05-07 19:05:54, Jan Kara wrote:
> >>   Hello,
> >>
> >>   attached is a patch that fixes possible leakage of free blocks / use of
> >> free blocks in UDF (which spilled nice assertion failures I've added in my
> >> first round of patches). More details in the changelog. Andrew, please apply.
> >> Both changes have survived some time of fsx and fsstress testing so they
> >> should be reasonably safe.
> >   Sorry for replying to myself but this patch had a minor problem of
> > printing some bogus warnings when directories were deleted (I wonder why
> > fsstress didn't find it). Attached is a new version of the patch without
> > this problem.
> 
> Jan, something seems busted here.  I'm getting lockups when testing udf
> on a single cpu with this last patch in place...
  Hmm, strange, I was also testing on UP and without problems. And I didn't
change any locking...

> I think it's the BKL stumbling on itself.
> 
> for example...
> 
> static int udf_symlink(struct inode * dir, struct dentry * dentry, const
> char * symname)
> {
> ...
>         lock_kernel();
> ...
> out:
>         unlock_kernel();
>         return err;
> 
> out_no_entry:
>         inode_dec_link_count(inode);
>         iput(inode);
>         goto out;
> }
> 
> but iput goes
> iput->iput_final->drop_inode->udf_drop_inode->lock_kernel() again
  As Andrew already wrote, BKL is free to recurse...

> looking for the right way around it but figured I'd ping you early :)
  Thanks for info - I'm now mostly out of email for a few days but I'll
have a look at it as soon as I return.

								Honza
-- 
Jan Kara <jack@...e.cz>
SuSE CR Labs
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