Where is the place of specifying automount options for a specific file system

Zhu, Peter J peter.j.zhu at intel.com
Fri Dec 4 03:29:36 PST 2009



> Hey,
> 
> Sorry I missed your reply
> > Using /etc/fstab?? I don't understand. For fixed partition, yes, it's
> > anaconda's job to manipulate this file do right thing.
> 
> Yeah, the OS installer typically writes out the /etc/fstab file for swap
> and other filesystems used for the OS (e.g. /usr).
> 
> > But for a
> > hot-plugged device like a USB disk , we shouldn't use this file. We
> > should do it with something like udev rules, I think. And for your
> > info, mount show
> > "(rw,nosuid,nodeve,uhelper=devkit,uid=500,gid=500,shortname=mixed,dmas
> > k=0077,utf8=1,flush)" for a usb disk. I want to know where are the
> > mount options from?
> 
> The way it works is that the desktop session that decides to mount the
> device (for GNOME, this is Nautilus/GVfs) calls the FilesystemMount()
> method for the device
> 
> http://hal.freedesktop.org/docs/DeviceKit-disks/Device.html#Device.Filesyste
> mMount
> 
> This method does take an array of mount options to use. The daemon then
> combines the given mount options with the defaults, see
> 
> http://cgit.freedesktop.org/DeviceKit/DeviceKit-disks/tree/src/devkit-disks-dev
> ice.c?id=009#n4277
> 
> and checks that forbidden mount options are passed (the user passing the
> 'dev' or 'suid' mount option would easily give him root, for example).
> If things check out, we create the mount point and mount the device.
> 
> GNOME, however never passes any mount options. Presumably the GNOME
> developers (am I'm one of them - I wrote most of the storage hotplugging
> code in GNOME) could read mount options from things like GConf (like
> gnome-mount did) but after thinking a lot about it we decided to not do
> this - see this bug and this message
> 
>  https://bugzilla.gnome.org/show_bug.cgi?id=586708
>  http://lists.freedesktop.org/archives/devkit-devel/2009-June/000225.html
> 
> for some details. If it turns out it is needed we can always just change
> GNOME to pass mount options and if needed we can always read them from
> things like GConf/GSettings/DConf and provide an UI to edit them.
> 
> Note that the daemon will always respect the contents of the /etc/fstab
> file - so if you put in lines like
> 
>  /dev/disk/by-label/My_Photos /media/My_Photos vfat
> shortname=lower,dmask=0000,users 0 0
> 
> then it will be used. You can also use the /disk/disk/by-path symlinks
> to set mount options for any device plugged into a given port.
> 
> > > I'm curious though - what mount options do you need to change? The
> > > defaults should work out of the box.
> > >
> > Yes, works. Just want to know how it works.
> 
> OK, good. FWIW, My gut feeling is that if the user needs to pass mount
> options for mounting local filesystems then the filesystem driver is
> probably doing something wrong. I really don't think a "edit mount
> options" in the normal desktop shell experience makes any sense on a
> modern desktop - we should be able to autodetect things out of the box.
> 
> Note that Palimpsest Disk Utility and udisks (aka DeviceKit-disks) in
> the future will provide an UI to edit the /etc/fstab file so the admin
> can decide that some filesystem should be mounted at boot- and/or
> plug-in-time.
> 
> (In addition, there are also plans for Palimpsest/udisks to provide UI
> to toggle whether things like RAID arrays and LVM Volume Groups should
> be started at boot- and/or plug-in-time. FWIW, nowadays I don't consider
> Palimpsest part of the normal desktop shell - it is a utility used by
> admins to set up storage for workstations and servers. It is still
> useful for the desktop shell experience but the desktop shell already
> provides simpler tools (built on exactly the same code) for formatting
> and starting/stopping things like RAID.)
> 
> I hope this clarifies.
>
Thanks, very very clear.

 
> Thanks,
> David
> 



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