On 08/26/2011 08:00 PM, Thomas Bächler wrote:
Am 26.08.2011 20:24, schrieb Gerardo Exequiel Pozzi:
Those are kernel modules, not block devices. Depending on kernel
configuration, they might be present or not.
Sure those are an abstraction of block devices that you have (real or
virtual).
What I am looking for is a counter for the block device itself (LVM
shows the "open count", I would hope that is not dm-specific).
Not per device, but for the whole abstraction:
Again /sys/module/$blk/refcnt, but seems that needs an example to trust me:
No, they are not. They are modules, random pieces of code that you can
load and unload. They are not an abstraction of anything.
Maybe I am expressed bad,,, mmm how to say...
* sd_mod provides an abstraction layer of scsi block disk devices. If
they are not abstraction, should not exists.
* Each instance of sd_mod is a block device.
* refcnt of blocks devices is per usage of these instances.
But you want to know the usage per block device.
Under deinitramfs stage we have.
* No user processes except the current script and init. (of course if no
proccess stalled, anyway there is nothing to do with "D" process)
* Unmounting all things, deregister all dm-mapper devices, and detaching
loop devs....
* There is no much things to do, just say to kernel "hey, start
poweroff/reboot/halt sequence!")
And for "general scenario".... all things started are stopped before
entering at this stage, also all real filesystem (except /). Deinitramfs
stage is just for unmount /, There is nothing (mounts) underlying of /
(of course there is rootfs, but do not care in this discussion).
In the particular case of archiso we have more things (mounted) below /,
we have a dm-0 that is part of two loop devs, and these loops devs
reside on a two level _mount_ for RO part and one level _mount_ for cow
part RW.
Looks like this ends in nothing, or I do not understand where or how far
you get. sorry.
--
Gerardo Exequiel Pozzi
\cos^2\alpha + \sin^2\alpha = 1
