From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Wed, 27 Sep 2006 15:57:05 +0200
From: Ingo Molnar <mingo@elte.hu>
Message-ID: <20060927135705.GA30311@elte.hu>
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Subject: [linux-lvm] Re: [RFC] Reverting "bd_mount_mutex" to "bd_mount_sem"
Reply-To: LVM general discussion and development <linux-lvm@redhat.com>
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To: Srinivasa Ds <srinivasa@in.ibm.com>
Cc: dm-devel@redhat.com, linux-kernel@vger.kernel.org, agk@redhat.com, linux-lvm@redhat.com


* Srinivasa Ds <srinivasa@in.ibm.com> wrote:

>   On debugging I found out that,"dmsetup suspend <device name>" calls 
> "freeze_bdev()",which locks "bd_mount_mutex" to make sure that no new 
> mounts happen on bdev until thaw_bdev() is called.
>   This "thaw_bdev()" is getting called when we resume the device 
> through "dmsetup resume <device-name>".
>   Hence we have 2 processes,one of which locks 
> "bd_mount_mutex"(dmsetup suspend) and Another(dmsetup resume) unlocks 
> it.

hm, to me this seems quite a fragile construct - even if the 
mutex-debugging warning is worked around by reverting to a semaphore.

	Ingo