aufs root filesystem

[gravyface]

Yes, that did it. Thanks!

For the record, I added "rootflags=barrier=0" to the kernel command line. ("nobarrier" seems to be the XFS equivalent). Next step is to update grub2 so it happens automatically...

I'm having the same issue: remountrw appears to "work" although no changes are committed after a reboot.

cat /proc/mounts (before remountrw):

rootfs / rootfs rw 0 0
none /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
none /proc proc rw,nosuid,nodev,noexec,relatime 0 0
udev /dev tmpfs rw,relatime,mode=755 0 0
/dev/disk/by-uuid/2f4daaaa-ec96-426c-be68-f4bb6bfe4166 /ro ext4 ro,relatime,barrier=0,data=ordered 0 0
none /sys/kernel/security securityfs rw,relatime 0 0
aufs-tmpfs /rw tmpfs rw,relatime 0 0
aufs / aufs rw,relatime,si=82ce0764d1af8a79 0 0
none /sys/fs/fuse/connections fusectl rw,relatime 0 0
none /sys/kernel/debug debugfs rw,relatime 0 0
none /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
none /dev/shm tmpfs rw,nosuid,nodev,relatime 0 0
tmpfs /tmp tmpfs rw,relatime 0 0
none /var/run tmpfs rw,nosuid,relatime,mode=755 0 0
none /var/lock tmpfs rw,nosuid,nodev,noexec,relatime 0 0
none /lib/init/rw tmpfs rw,nosuid,relatime,mode=755 0 0
tmpfs /var/log tmpfs rw,relatime 0 0
tmpfs /var/tmp tmpfs rw,relatime 0 0
tmpfs /var/lib/dhcp3 tmpfs rw,relatime 0 0
binfmt_misc /proc/sys/fs/binfmt_misc binfmt_misc rw,nosuid,nodev,noexec,relatime 0 0
gvfs-fuse-daemon /home/cmhaadmin/.gvfs fuse.gvfs-fuse-daemon rw,nosuid,nodev,relatime,user_id=1000,group_id=1000 0 0

Here's what it looks like after running remountrw:

rootfs / rootfs rw 0 0
none /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
none /proc proc rw,nosuid,nodev,noexec,relatime 0 0
udev /dev tmpfs rw,relatime,mode=755 0 0
/dev/disk/by-uuid/2f4daaaa-ec96-426c-be68-f4bb6bfe4166 /ro ext4 rw,relatime,barrier=0,data=ordered 0 0
none /sys/kernel/security securityfs rw,relatime 0 0
aufs-tmpfs /rw tmpfs rw,relatime 0 0
aufs / aufs rw,relatime,si=82ce0764d1af8a79 0 0
none /sys/fs/fuse/connections fusectl rw,relatime 0 0
none /sys/kernel/debug debugfs rw,relatime 0 0
none /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
none /dev/shm tmpfs rw,nosuid,nodev,relatime 0 0
tmpfs /tmp tmpfs rw,relatime 0 0
none /var/run tmpfs rw,nosuid,relatime,mode=755 0 0
none /var/lock tmpfs rw,nosuid,nodev,noexec,relatime 0 0
none /lib/init/rw tmpfs rw,nosuid,relatime,mode=755 0 0
tmpfs /var/log tmpfs rw,relatime 0 0
tmpfs /var/tmp tmpfs rw,relatime 0 0
tmpfs /var/lib/dhcp3 tmpfs rw,relatime 0 0
binfmt_misc /proc/sys/fs/binfmt_misc binfmt_misc rw,nosuid,nodev,noexec,relatime 0 0
gvfs-fuse-daemon /home/cmhaadmin/.gvfs fuse.gvfs-fuse-daemon rw,nosuid,nodev,relatime,user_id=1000,group_id=1000 0 0

As you can see, the rw flag is set after remounting, but making changes doesn't commit (I tried 'touch foobar' in my sudo user's home directory, and then running remountro and rebooting).

My grub.cfg has been edited manually (that was another adventure altogether) for now, will fix once I have this working.

Here's my grub.cfg:

#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by /usr/sbin/grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s /boot/grub/grubenv ]; then
  have_grubenv=true
  load_env
fi
set default="0"
if [ ${prev_saved_entry} ]; then
  saved_entry=${prev_saved_entry}
  save_env saved_entry
  prev_saved_entry=
  save_env prev_saved_entry
fi
insmod ext2
set root=(hd0,1)
search --no-floppy --fs-uuid --set 2f4daaaa-ec96-426c-be68-f4bb6bfe4166
if loadfont /usr/share/grub/unicode.pf2 ; then
  set gfxmode=640x480
  insmod gfxterm
  insmod vbe
  if terminal_output gfxterm ; then true ; else
    # For backward compatibility with versions of terminal.mod that don't
    # understand terminal_output
    terminal gfxterm
  fi
fi
if [ ${recordfail} = 1 ]; then
  set timeout=-1
else
  set timeout=10
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/white
### END /etc/grub.d/05_debian_theme ###



### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.

# aufs read-only grub menu items
menuentry "Ubuntu, Linux 2.6.31-20-generic READ-ONLY" {
        recordfail=1
        if [ -n ${have_grubenv} ]; then save_env recordfail; fi
        set quiet=1
        insmod ext2
        set root=(hd0,1)
        search --no-floppy --fs-uuid --set 2f4daaaa-ec96-426c-be68-f4bb6bfe4166
        linux   /boot/vmlinuz-2.6.31-20-generic root=UUID=2f4daaaa-ec96-426c-be68-f4bb6bfe4166 ro quiet splash aufs=tmpfs rootflags=barrier=0
        initrd  /boot/initrd.img-2.6.31-20-generic
}

menuentry "Ubuntu, Linux 2.6.31-20-generic WRITEABLE" {
        recordfail=1
        if [ -n ${have_grubenv} ]; then save_env recordfail; fi
        set quiet=1
        insmod ext2
        set root=(hd0,1)
        search --no-floppy --fs-uuid --set 2f4daaaa-ec96-426c-be68-f4bb6bfe4166
        linux   /boot/vmlinuz-2.6.31-20-generic root=UUID=2f4daaaa-ec96-426c-be68-f4bb6bfe4166 ro quiet splash
        initrd  /boot/initrd.img-2.6.31-20-generic
}


menuentry "Ubuntu, Linux 2.6.31-20-generic (recovery mode)" {
        recordfail=1
        if [ -n ${have_grubenv} ]; then save_env recordfail; fi
        insmod ext2
        set root=(hd0,1)
        search --no-floppy --fs-uuid --set 2f4daaaa-ec96-426c-be68-f4bb6bfe4166
        linux   /boot/vmlinuz-2.6.31-20-generic root=UUID=2f4daaaa-ec96-426c-be68-f4bb6bfe4166 ro single
        initrd  /boot/initrd.img-2.6.31-20-generic
}

### END /etc/grub.d/40_custom ###



### BEGIN /etc/grub.d/20_memtest86+ ###
menuentry "Memory test (memtest86+)" {
        linux16 /boot/memtest86+.bin
}
menuentry "Memory test (memtest86+, serial console 115200)" {
        linux16 /boot/memtest86+.bin console=ttyS0,115200n8
}
### END /etc/grub.d/20_memtest86+ ###

### BEGIN /etc/grub.d/30_os-prober ###
if [ ${timeout} != -1 ]; then
  if keystatus; then
    if keystatus --shift; then
      set timeout=-1
    else
      set timeout=0
    fi
  else
    if sleep --interruptible 3 ; then
      set timeout=0
    fi
  fi
fi
### END /etc/grub.d/30_os-prober ###

[gravyface]

Ok as a test (and after looking at /proc/mounts a bit more carefully), I ran remountrw and touched a file in /ro/home/gravyface, remountro'ed, and rebooted and the file was present in /home/gravyface.

Is this the expected behavior? I could've sworn that with Voyage Linux (which this rootaufs script is based off of) you could run the system normally when remountrw'ed (i.e. apt-get install/remove, etc.). Am I missing something?

I'm following these instructions:
https://help.ubuntu.com/community/au...stemOnUsbFlash

Running Ubuntu 9.10 2.6.31-20 64-bit; /dev/sda1 is a CompactFlash card (SATA-to-CF adapter) formatted with Ext4.

[Perkins]

For what it's worth, Puppy Linux does exactly this kind of thing when running from a flash drive... You might take a look at their scripts and see if they're easily convertible for a full-size distribution...

[zagaeski]

Many thanks for this script! I use it every day. It really does the trick.

I often remountrw or mount a scratch partition to store things across reboots. Of course, sometimes I forget to remountro before rebooting. I've noticed that this always causes fsck to complain about improper unmounting. After a little looking around it became clear that the umountfs and umountroot scripts in /etc/init.d are not set up to handle the rootaufs scenario. To fix them I added the following lines to the rootaufs script (after the fstab fixes):

cat /aufs/ro/etc/init.d/umountfs | \
    sed 's:\(PROTECTED_MOUNTS.*\)\^.... .. .. /:\1^aufs.* \\/ /:' \
    | sed 's:\(^\s*/|/proc.*\)):\1|/ro|/rw):' >/aufs/etc/init.d/umountfs

cat /aufs/ro/etc/init.d/umountroot | \
    sed 's:\(\s*\)\(mount.*dummytype.*dummydev.*\):\1for aroot in /ro /rw /; do\n\1\2:' \
    | sed '/mount.*dummytype.*dummydev/,/ES=/s:\(\s*\)\(.*\) /\([ ]*\):\1    \2 $aroot\3:' \
    | sed 's/\(\s*\)ES=\$?/\1done\n\1ES=$?/' >/aufs/etc/init.d/umountroot

umountfs is expecting a /proc/mounts that has a line starting with "/some-dev / " somewhere after the first line. It leaves anything above this line mounted. In the rootaufs case, the script should instead look for a line starting with "aufs / ". As an extra precaution, add /ro and /rw to the list of mounts that umountfs should not touch.

For umountroot, run a loop that umounts /ro /rw and finally /, instead of just umounting /. I'm not certain what the best order is for umounting these, but this seems to work.


Cheers,
Brendan

[kangarooks]

I run this script on 11.04 and i have following errors:

from gnome panel:

"Indicator Applet Session" has quit unexpectedly
"Indicator Applet" has quit unexpectedly

and i have no sound

dmesg shows:

dmesg | cut -d ']' -f 2 | grep hardlink| sort | uniq
non-accessible hardlink creation was attempted by: compiz (fsuid 1000)
 non-accessible hardlink creation was attempted by: gconfd-2 (fsuid 1000)
 non-accessible hardlink creation was attempted by: gconfd-2 (fsuid 106)
 non-accessible hardlink creation was attempted by: gdm-session-wor (fsuid 1000)
 non-accessible hardlink creation was attempted by: gdm-simple-slav (fsuid 106)
 non-accessible hardlink creation was attempted by: gvfsd-metadata (fsuid 1000)
 non-accessible hardlink creation was attempted by: indicator-apple (fsuid 1000)
 non-accessible hardlink creation was attempted by: opera (fsuid 1000)
 non-accessible hardlink creation was attempted by: pulseaudio (fsuid 1000)
 non-accessible hardlink creation was attempted by: ubuntuone-login (fsuid 1000)
 non-accessible hardlink creation was attempted by: ubuntuone-syncd (fsuid 1000)
 non-accessible hardlink creation was attempted by: zeitgeist-daemo (fsuid 1000)

and couple of:

Error in vfs_unlink; rc = [-1]

apparmor is off

help pls, since i really wanna have my linux on pendrive

[mcduck]

Considering that this is years old thread, and has absolutely nothing to do with the problem you are having, you really should just start a new thread of your own, with a title related to your problem.

[kangarooks]

k, found solution for it:

kernel.yama.protected_nonaccess_hardlinks=0 in boot options /etc/defautls/grub fixes it

https://bugs.launchpad.net/ubuntu/+s...ux/+bug/663069

[kangarooks]

and that solution doesnt fix the problem... sucks, time to go for plan b, which is by hand tmpfs-aufs the main offenders... oh well

[kangarooks]

Considering that this is years old thread, and has absolutely nothing to do with the problem you are having, you really should just start a new thread of your own, with a title related to your problem.

no.

i would suggest you should drop passive-agressive and/or authoritarian tone from your future posts, and maybe read what is really going on (i.e. that my post has EVERYTHING to do with aufs on root on ubuntu).

also, the help.ubuntu.com/community/aufsRootFileSystemOnUsbFlash howto points to this thread, if youre owner of that howto then please fix that...

kthxbai

[chainu127]

I also came across the non-accessible hardlink creation problem, with xbmc. As stated, the kernel option kernel.yama.protected_nonaccess_hardlinks=0 is what needs to be done, but passing it as a kernel option in GRUB does not work. My solution was to embed it in a startup script instead:

sudo nano -w /etc/init.d/hardlinks_fix

then save this in the new file:

#! /bin/sh
# /etc/init.d/hardlinks_fix
#

sysctl -w kernel.yama.protected_nonaccess_hardlinks=0

exit 0

make it executable and add it to the default runlevel:

sudo chmod +x /etc/init.d/hardlinks_fix

sudo update-rc.d hardlinks_fix defaults

After this, and the AppArmor workaround "aa-complain dhclient3" to get networking under aufs, xbmc seems to be working for me and I don't have the hardlinks creation error anymore.