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Date:      Sat, 21 Jul 2007 11:06:03 +1000
From:      Norberto Meijome <freebsd@meijome.net>
To:        "M. Warner Losh" <imp@bsdimp.com>
Cc:        LoN_Kamikaze@gmx.de, olli@lurza.secnetix.de, freebsd-stable@freebsd.org, idiotbg@gmail.com, josh@tcbug.org
Subject:   Re: removing external usb hdd without unmounting causes reboot?
Message-ID:  <20070721110603.3878d933@localhost>
In-Reply-To: <20070719.090250.1387160138.imp@bsdimp.com>
References:  <20070719130252.6880b967@localhost> <469F101C.5060906@gmx.de> <200707190943.55428.idiotbg@gmail.com> <20070719.090250.1387160138.imp@bsdimp.com>

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On Thu, 19 Jul 2007 09:02:50 -0600 (MDT)
"M. Warner Losh" <imp@bsdimp.com> wrote:

> In message: <200707190943.55428.idiotbg@gmail.com>
>             Momchil Ivanov <idiotbg@gmail.com> writes:
> : What is then the reason for the kernel not being able to unmount a
> : filesystem whose provider is no longer present?
> 
> The problem is that the device driver has wound down, deallocated
> memory, etc.  Now the kernel comes along with stale references to the
> device and panic ensues.  It is really just that simple.  There's no
> replacement of the now-dead device with dead calls.
> 
> And even if you fixed that, most of the file systems in the tree today
> do not tolerate errors on writes at all and that also leads to
> panics.  This is why firewire freezes the I/Os rather than failing
> them (and why umount -f on a firewire drive hangs).

Please point me to the correct RTFM, because I feel this worth it :)

Is there a reason why the kernel cannot check 'upwards' if a device is being used, ie mounted ? and prevent the unloading of the device driver ? 

thanks for your time illuminating this ignoramus :)

_________________________
{Beto|Norberto|Numard} Meijome

"Egotism is the anesthetic that dulls the pain of stupidity."
  Frank Leahy

I speak for myself, not my employer. Contents may be hot. Slippery when wet. Reading disclaimers makes you go blind. Writing them is worse. You have been Warned.


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