Re: Changing label of a mounted XFS filesystem

Dave Chinner
2014-07-03T23:12:22Z

On Thu, Jul 03, 2014 at 04:14:08PM +0200, Matthias Schniedermeyer wrote:
> On 03.07.2014 20:07, Jeff Liu wrote:
> > Hi,
> >
> > On 07/03/2014 07:29 PM, Matthias Schniedermeyer wrote:
> > > Hi
> > >
> > >
> > > Is there a particular reason that the label of a mounted XFS fileystem
> > > can't be changed?
> >
> > Maybe since we have no user request for this function? :)

Most likely. It's currently done by xfs_db, which is an offline
tool.

> > > The man-page of xfs_admin gives a blanket "Devices that are mounted
> > > cannot be modified" but no explanation for why that is.
> > >
> > > In my case it's the label of the root-filesystem i want to change. So to
> > > change it i would have to boot the computer with some kind of live or
> > > rescure-system. Or i would need to temporarily connect the device to
> > > another computer, both aren't really nice hoops to jump through just to
> > > change a few characters.
> > >
> > > The only thing i can compare this to is ext2 and with ext2 (/boot
> > > partition, so it really is ext2) i can change the label to my hearts
> > > content, even the device is mounted.
> > >
> > > For my case i could live with it if i could remount the filesystem RO,
> > > change the label and then having to reboot the machine, still nicer than
> > > the other 2 options.
> >
> > Btrfs support set/change label on a mounted file system via ioctl(2), maybe we
> > can implement it if that sounds useful to our users.
>
> I would vote for that, i've run into this particular brickwall several
> times over the years.

There's a bunch of things I'd like to make online modifiable that
currently can only be done offline by xfs_db and other tools. I'll
add this to the list, and hopefully when I get a little time I'll do
something about it...

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com