Forced unmounting for removable devices

From: Eduard-Gabriel Munteanu
Date: Wed Aug 29 2007 - 21:51:49 EST


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This might have been discussed a few years ago, but things have changed. I'm talking about patches like this one (I'm not the author): http://developer.osdl.org/dev/fumount/#kernel1

The current situation requires a way to forcibly unmount removable media. Consider the following (real) scenario. Someone has a box with hald + dbus + ivman to support "supermounting" the CDROM drive. He has to install a 2 CD application using Wine for example, but the setup application prevents normal unmounting of the first one. Then he goes on and pushes the button to eject the CD, lazy-unmounting the media. The kernel goes mad and all attempts to load the second CD fail (the kernel hasn't got rid of the first fs).

If there was anything like a real forced unmounting, things would have worked well, as on MS Windows itself.

As far as I can see, there is no other sane way to solve such problems. So, what's keeping such patches from making their way into the mainstream kernel? All (but maybe I haven't searched enough) arguments against such a feature that I've seen by now just say "it's not needed", "it's not worth it" and so on, and many of them refer to network mounts.

P.S.: I'm not saying lazy unmounting should be replaced. They both make sense, depending on the scenario.
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