On 22 Jan 2010, at 10:40, Leszek Ciesielski wrote: > On Fri, Jan 22, 2010 at 10:30 AM, Thomas Kupper <thomas@xxxxxxxxxx> wrote: >> >> On 22 Jan 2010, at 10:17, Leszek Ciesielski wrote: >> >>> On Fri, Jan 22, 2010 at 10:06 AM, Thomas Kupper <thomas@xxxxxxxxxx> wrote: >>>> >>>> On 22 Jan 2010, at 09:59, Leszek Ciesielski wrote: >>>> >>>>> On Fri, Jan 22, 2010 at 12:55 AM, Thomas Kupper <thomas@xxxxxxxxxx> 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. > > Doesn't 'cat /proc/mounts' show the actually used mount options? No, it doesn't in my case - Ubuntu 9.10 with 2.6.32-10-generic kernel. thomas # cat /proc/mounts | fgrep ' / ' rootfs / rootfs rw 0 0 /dev/sda3 / btrfs rw,relatime 0 0 thomas # cat /proc/cmdline [...] root=/dev/sda3 ro rootflags=subvol=rootfs-snapshot-001-- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
