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Date: Fri, 1 Jun 2007 20:49:26 +0400
From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Eric Sandeen <sandeen@sandeen.net>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       LKML <linux-kernel@vger.kernel.org>, Jan Kara <jack@suse.cz>
Subject: Re: [PATCH 2/2] Fix possible leakage of blocks in UDF
Message-ID: <20070601164926.GA8398@cvg>
References: <20070524165935.GB19709@duck.suse.cz> <20070524170554.GC19709@duck.suse.cz> <20070524203653.GA7693@duck.suse.cz> <465DF0B4.2050203@sandeen.net> <465DF91F.3010201@sandeen.net> <20070531174201.GB8392@cvg> <465F09E7.7000300@sandeen.net>
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[Eric Sandeen - Thu, May 31, 2007 at 12:46:15PM -0500]
| Cyrill Gorcunov wrote:
| 
| >Eric, could you please try the following:
| >
| >1) declare the spinlock in the top of inode.c as
| >
| >	DEFINE_SPINLOCK(udf_drop_lock);
| >
| >2) replace in udf_drop_inode()
| >
| >	kernel_lock -> spin_lock(&udf_drop_lock);
| >	kernel_unlock -> spin_unlock(&udf_drop_lock);
| >
| >I'm not sure if it help but you may try ;)
| >
| >		Cyrill
| >
| 
| I'm sure it'll avoid the deadlock but....
| 
| Any sense of what the BKL is actually trying to protect in this case?
| 
| Is it really only trying to prevent concurrent prealloc-discarders, or 
| is there more?
| 
| -Eric
| 

Hi Eric,
it seems BKL only trying to protect from concurrent discard_prealloc.
Moreover, a lot of UDF code does call iput with BKL held, so the only
solution I see is to add spinlocks to udf_drop_inode... I'm making patch
soon. Any comments?

		Cyrill