[lxc-devel] [PATCH] handle clone of btrfs snapshots

[Stéphane Graber]

On 12-09-26 02:11 PM, Serge Hallyn wrote:
> Quoting Dwight Engen (dwight.engen at oracle.com):
>>
>> Fix determination of $oldroot from the config file. The old code had the '
>> in the wrong place and didn't account for whitespace between the = and
>> the rootfs.
>>
>> Set $rootfs based on $oldroot instead of forcing it to be in
>> $lxc_path/$lxc_new/rootfs. This allows for btrfs snapshot to be made even if
>> $lxc_path isn't on the same filesystem. If $oldroot isn't a subvolume,
>> fall back to making a copy.
>>
>> Signed-off-by: Dwight Engen <dwight.engen at oracle.com>
> 
> Thanks, Dwight, very nice.
> 
> Acked-by: Serge E. Hallyn <serge.hallyn at ubuntu.com>

Pushed to staging branch.

>> ---
>>  src/lxc/lxc-clone.in |   19 +++++++++----------
>>  1 files changed, 9 insertions(+), 10 deletions(-)
>>
>> diff --git a/src/lxc/lxc-clone.in b/src/lxc/lxc-clone.in
>> index 3e22229..04ef20b 100644
>> --- a/src/lxc/lxc-clone.in
>> +++ b/src/lxc/lxc-clone.in
>> @@ -183,13 +183,13 @@ if [ -e  $lxc_path/$lxc_orig/fstab ];then
>>  fi
>>  
>>  echo "Copying rootfs..."
>> -rootfs=$lxc_path/$lxc_new/rootfs
>> +oldroot=`grep lxc.rootfs $lxc_path/$lxc_orig/config | awk -F'[= \t]+' '{ print $2 }'`
>> +rootfs=`echo $oldroot |sed "s/$lxc_orig/$lxc_new/"`
>>  
>>  container_running=True
>>  lxc-info -s -n $lxc_orig|grep RUNNING >/dev/null 2>&1 || container_running=False
>>  
>>  sed -i '/lxc.rootfs/d' $lxc_path/$lxc_new/config
>> -oldroot=`grep lxc.rootfs $lxc_path/$lxc_orig/config | awk -F= '{ print $2 '}`
>>  if [ -b $oldroot ]; then
>>      type vgscan || { echo "$(basename $0): lvm is not installed" >&2; false; }
>>      lvdisplay $oldroot > /dev/null 2>&1 || { echo "$(basename $0): non-lvm blockdev cloning is not supported" >&2; false; }
>> @@ -221,7 +221,7 @@ if [ -b $oldroot ]; then
>>          lvcreate -L $lxc_size $lxc_vg -n ${lxc_lv_prefix}$lxc_new
>>          echo "lxc.rootfs = /dev/$lxc_vg/${lxc_lv_prefix}$lxc_new" >> $lxc_path/$lxc_new/config
>>          # and mount it so we can tweak it
>> -        mkdir -p $lxc_path/$lxc_new/rootfs
>> +        mkdir -p $rootfs
>>          mkfs -t $fstype /dev/$lxc_vg/${lxc_lv_prefix}$lxc_new
>>          mount /dev/$lxc_vg/${lxc_lv_prefix}$lxc_new $rootfs || { echo "$(basename $0): failed to mount new rootfs" >&2; false; }
>>          mounted=1
>> @@ -233,16 +233,15 @@ if [ -b $oldroot ]; then
>>          lvrename $lxc_vg/${lxc_lv_prefix}${lxc_new}_snapshot $lxc_vg/${lxc_lv_prefix}$lxc_new
>>          echo "lxc.rootfs = /dev/$lxc_vg/${lxc_lv_prefix}$lxc_new" >> $lxc_path/$lxc_new/config
>>          # and mount it so we can tweak it
>> -        mkdir -p $lxc_path/$lxc_new/rootfs
>> +        mkdir -p $rootfs
>>          mount /dev/$lxc_vg/${lxc_lv_prefix}$lxc_new $rootfs || { echo "$(basename $0): failed to mount new rootfs" >&2; false; }
>>          mounted=1
>>      fi
>>  
>> -elif out=$(btrfs subvolume list "$lxc_path/$lxc_orig/rootfs" 2>&1); then
>> -
>> -    out=$(btrfs subvolume snapshot "$lxc_path/$lxc_orig/rootfs" "$rootfs" 2>&1) || { echo "$(basename $0): btrfs snapshot failed" >&2; false; }
>> +elif which btrfs >/dev/null 2>&1 && btrfs subvolume list $oldroot >/dev/null 2>&1; then
>> +    # if oldroot is a btrfs subvolume, assume they want a snapshot
>> +    btrfs subvolume snapshot "$oldroot" "$rootfs" 2>&1 || { echo "$(basename $0): btrfs snapshot failed" >&2; false; }
>>      echo "lxc.rootfs = $rootfs" >> "$lxc_path/$lxc_new/config"
>> -
>>  else
>>      if [ $snapshot = "yes" ]; then
>>          echo "$(basename $0): cannot snapshot a directory" >&2
>> @@ -252,8 +251,8 @@ else
>>          lxc-freeze -n $lxc_orig
>>          frozen=1
>>      fi
>> -    mkdir -p $lxc_path/$lxc_new/rootfs/
>> -    rsync -ax $lxc_path/$lxc_orig/rootfs/ $lxc_path/$lxc_new/rootfs/
>> +    mkdir -p $rootfs/
>> +    rsync -ax $oldroot/ $rootfs/
>>      echo "lxc.rootfs = $rootfs" >> $lxc_path/$lxc_new/config
>>      if [ $container_running = "True" ]; then
>>          lxc-unfreeze -n $lxc_orig
>> -- 
>> 1.7.1
>>
>>
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-- 
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com

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