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? Cheers, Thomas-- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Jan 22, 2010 at 12:55 AM, Thomas Kupper <thomas@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. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 22 Jan 2010, at 09:59, Leszek Ciesielski wrote:> On Fri, Jan 22, 2010 at 12:55 AM, Thomas Kupper <thomas@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.-- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Jan 22, 2010 at 10:06 AM, Thomas Kupper <thomas@kupper.org> wrote:> > On 22 Jan 2010, at 09:59, Leszek Ciesielski wrote: > >> On Fri, Jan 22, 2010 at 12:55 AM, Thomas Kupper <thomas@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 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 22 Jan 2010, at 10:17, Leszek Ciesielski wrote:> On Fri, Jan 22, 2010 at 10:06 AM, Thomas Kupper <thomas@kupper.org> wrote: >> >> On 22 Jan 2010, at 09:59, Leszek Ciesielski wrote: >> >>> On Fri, Jan 22, 2010 at 12:55 AM, Thomas Kupper <thomas@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=ext4Again, 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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Jan 22, 2010 at 10:30 AM, Thomas Kupper <thomas@kupper.org> wrote:> > On 22 Jan 2010, at 10:17, Leszek Ciesielski wrote: > >> On Fri, Jan 22, 2010 at 10:06 AM, Thomas Kupper <thomas@kupper.org> wrote: >>> >>> On 22 Jan 2010, at 09:59, Leszek Ciesielski wrote: >>> >>>> On Fri, Jan 22, 2010 at 12:55 AM, Thomas Kupper <thomas@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.Doesn''t ''cat /proc/mounts'' show the actually used mount options? -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 22 Jan 2010, at 10:40, Leszek Ciesielski wrote:> On Fri, Jan 22, 2010 at 10:30 AM, Thomas Kupper <thomas@kupper.org> wrote: >> >> On 22 Jan 2010, at 10:17, Leszek Ciesielski wrote: >> >>> On Fri, Jan 22, 2010 at 10:06 AM, Thomas Kupper <thomas@kupper.org> wrote: >>>> >>>> On 22 Jan 2010, at 09:59, Leszek Ciesielski wrote: >>>> >>>>> On Fri, Jan 22, 2010 at 12:55 AM, Thomas Kupper <thomas@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. > > 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html