[linux-lvm] Re: [RFC] Reverting "bd_mount_mutex" to "bd_mount_sem"

Ingo Molnar mingo at elte.hu
Wed Sep 27 13:57:05 UTC 2006

* Srinivasa Ds <srinivasa at 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.

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