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Message-ID: <2cd57c900512200131l4ff29837o@mail.gmail.com>
Date: Tue, 20 Dec 2005 17:31:12 +0800
From: Coywolf Qi Hunt <coywolf@gmail.com>
To: sander@humilis.net
Subject: Re: [RFC] Let non-root users eject their ipods?
Cc: Willy Tarreau <willy@w.ods.org>, john stultz <johnstul@us.ibm.com>,
       lkml <linux-kernel@vger.kernel.org>, greg@kroah.com, axboe@suse.de,
       vandrove@vc.cvut.cz, aia21@cam.ac.uk, akpm@osdl.org
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2005/12/20, Sander <sander@humilis.net>:
> Coywolf Qi Hunt wrote (ao):
> > 2005/12/20, Willy Tarreau <willy@w.ods.org>:
> > > On Mon, Dec 19, 2005 at 06:51:58PM -0800, john stultz wrote:
> > > >       I'm getting a little tired of my roommates not knowing how to safely
> > > > eject their usb-flash disks from my system and I'd personally like it if
> > > > I could avoid bringing up a root shell to eject my ipod. Sure, one could
> > > > suid the eject command, but that seems just as bad as changing the
> > > > permissions in the kernel (eject wouldn't be able to check if the user
> > > > has read/write permissions on the device, allowing them to eject
> > > > anything).
> > >
> > > You may find my question stupid, but what is wrong with umount ? That's
> > > how I proceed with usb-flash and I've never sent any eject command to
> > > it (I even didn't know that the ioctl would be accepted by an sd device).
> >
> > IMHO, umount doesn't guarantee sync, isn't it?

Actually I was think umount(2), since this is the kernel list, but off
topic here.

>
> I'm pretty sure it does :-)

That is because: usually your removable media is not the file system
root, hence umount(8) can return successfully only if no processes are
busy working on it.

If you boot from or chroot/pivot into a removable media, and you
remount it ro, and unplug it, then you may lose data.

-- coywolf

>
> Anyway, that is how I treat all usb/firewire disks, and I've never lost
> data. Just umount and unplug when the prompt returns.
>
> --
> Humilis IT Services and Solutions
> http://www.humilis.net
>
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