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From: Christoph Hellwig <hch@lst.de>
To: Andrew Morton <akpm@osdl.org>
Cc: Attila Body <compi@freemail.hu>,
	linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>
Subject: Re: UDF madness
Date: Thu, 27 Jan 2005 11:03:54 +0100	[thread overview]
Message-ID: <20050127100354.GA10622@lst.de> (raw)
In-Reply-To: <20050126201141.59c90e69.akpm@osdl.org>

> Yes, me too.  generic_shutdown_super() takes lock_super().  And udf uses
> lock_super for protecting its block allocation data strutures.  Trivial
> deadlock on unmount.
> 
> Filesystems really shouldn't be using lock_super() for internal purposes,
> and the main filesystems have been taught to not do that any more, but UDF
> is a holdout.
> 
> It seems that this deadlock was introduced on Jan 5 by the "udf: fix
> reservation discarding" patch which added the udf_discard_prealloc() call
> into udf_clear_inode().  The below dopey patch prevents the deadlock, but
> perhaps we can think of something more appealing.  Ideally, use a new lock
> altogether?

Yes, the lock_super usage in UDF only protects it's block allocation and
doesn't try to cross-protect anything with the VFS usage of it.

I'll cook up a patch to add a balloc_mutex to the UDF superblock and
give it some testing. 


  parent reply	other threads:[~2005-01-27 10:04 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-01-25 21:24 UDF madness Attila Body
2005-01-27  4:11 ` Andrew Morton
2005-01-27  7:57   ` Al Viro
2005-01-27  9:30     ` Stephen C. Tweedie
2005-01-27  9:59       ` Al Viro
2005-01-27 10:03   ` Christoph Hellwig [this message]
2005-01-29 15:33   ` Christoph Hellwig

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