On 22 Jan 2010, at 10:17, Leszek Ciesielski wrote: > On Fri, Jan 22, 2010 at 10:06 AM, Thomas Kupper <tho...@kupper.org> wrote: >> >> On 22 Jan 2010, at 09:59, Leszek Ciesielski wrote: >> >>> On Fri, Jan 22, 2010 at 12:55 AM, Thomas Kupper <tho...@kupper.org> wrote: >>>> Using btrfs as the root filesystem on my Ubuntu 9.10 powered laptop I >>>> discoverd that mount is not showing the actual passed rootflags= but shows >>>> what is put in the /etc/fstab. >>>> >>>> First of all, I'm not sure if that is an intended behavior and if not, if >>>> it's a problem of mount or btrfs. >>>> >>>> Example: >>>> Following Goffredo's example there's a subvolume called rootfs which is - >>>> surprisingly ;) - the root of the linux. The corresponding line in fstab is >>>> >>>> $ cat /etc/fstab >>>> [...] >>>> # / was on /dev/sda3 during installation >>>> UUID=<some-scary-UUID> / btrfs subvol=rootfs 0 1 >>>> >>>> $ mount >>>> [...] >>>> /dev/sda3 on / type btrfs (rw,subvol=rootfs) >>>> >>>> I create a snapshot of the rootfs called rootfs-snap-001 and create it in >>>> the / of the btrfs volume itself. Not modifying grub2, I just edit grub on >>>> the go. While booting I edit the /linux-kernel... entry and replace >>>> rootflags=subvol=rootfs with rootflags=subvol=rootfs-snap-001. That boots >>>> up just fine but the mount output still is >>>> >>>> $ mount >>>> [...] >>>> /dev/sda3 on / type btrfs (rw,subvol=rootfs) >>>> >>>> ... and /etc/mtab is indeed >>>> >>>> $ cat /etc/mtab >>>> [...] >>>> /dev/sda3 / btrfs rw,subvol=rootfs 0 0 >>>> >>>> shouldn't mount and /etc/mtab reflect the parameters in use? >>>> >>> >>> No. The same thing happens with whatever filesystem you use for rootfs. >> >> Thanks for the clarification. How do I see then what subvolume is mounted as >> root? Assume I play around with lots of snapshots and wonder with what >> snapshot I booted. Sure, I should know but sometimes I want to make sure I >> did boot the right one before deleting an other snapshot. > > azazel ~ # cat /proc/cmdline > root=/dev/sda3 rootfstype=ext4
Again, thanks alot. That does the trick. Maybe a bit of a pain in the a$#: Is there a specific reason the mount utility doesn't show the actual mount options in use? Wouldn't one - I certainly do - expect /etc/mtab or mount to show how a certain partition is mounted? Not really a btrfs issue, I'm aware.-- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
