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From: Ingo Molnar <mingo@elte.hu>
To: Srinivasa Ds <srinivasa@in.ibm.com>
Cc: dm-devel@redhat.com, linux-lvm@redhat.com,
	linux-kernel@vger.kernel.org, agk@redhat.com
Subject: Re: [RFC] Reverting "bd_mount_mutex" to "bd_mount_sem"
Date: Wed, 27 Sep 2006 15:57:05 +0200	[thread overview]
Message-ID: <20060927135705.GA30311@elte.hu> (raw)
In-Reply-To: <451A78DF.1060901@in.ibm.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

WARNING: multiple messages have this Message-ID (diff)
From: Ingo Molnar <mingo@elte.hu>
To: Srinivasa Ds <srinivasa@in.ibm.com>
Cc: dm-devel@redhat.com, linux-kernel@vger.kernel.org,
	agk@redhat.com, linux-lvm@redhat.com
Subject: [linux-lvm] Re: [RFC] Reverting "bd_mount_mutex" to "bd_mount_sem"
Date: Wed, 27 Sep 2006 15:57:05 +0200	[thread overview]
Message-ID: <20060927135705.GA30311@elte.hu> (raw)
In-Reply-To: <451A78DF.1060901@in.ibm.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

  reply	other threads:[~2006-09-27 13:57 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-09-27 13:13 [RFC] Reverting "bd_mount_mutex" to "bd_mount_sem" Srinivasa Ds
2006-09-27 13:13 ` Srinivasa Ds
2006-09-27 13:13 ` [linux-lvm] " Srinivasa Ds
2006-09-27 13:57 ` Ingo Molnar [this message]
2006-09-27 13:57   ` [linux-lvm] " Ingo Molnar
2006-10-06 20:50   ` Eric Sandeen
2006-10-06 20:50     ` [linux-lvm] " Eric Sandeen
2006-10-10 15:04     ` Srinivasa Ds
2006-10-10 15:04       ` [linux-lvm] " Srinivasa Ds
2006-10-10 15:19       ` Arjan van de Ven
2006-10-10 15:19         ` Arjan van de Ven
2006-10-10 15:19         ` [linux-lvm] " Arjan van de Ven
2006-10-23  8:39         ` Roger Lucas

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