ENOTEMPTY on "rm -rf" for snapshot and subvolume

ENOTEMPTY on "rm -rf" for snapshot and subvolume

[Harshavardhana]

Hi Everyone,

      Recently i created a snapshot of an existing volume which had some 
amount of data.
      Now that after creating the snapshot i have tried deleting the 
same snapshot.  But i am
      getting ENOTEMPTY for "rmdir". But when i see the actual files 
inside are deleted
      not the parent directory.

      From the code it looks like

      if (inode->i_size > BTRFS_EMPTY_DIR_SIZE ||
             inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
                 return -ENOTEMPTY;

      Why would "unlink" succeeds for the files inside the directory?, 
yet returning ENOTEMPTY

      This looks odd after this, i  went ahead and tried deleting the 
the existing volume itself
      same result.

      So i was wondering if at all this is supposed to work this way, do 
i need to use "btrfs"
      commands to delete subvolumes always? and their relative snapshots?.

      But either in that case too returning ENOTEMPTY does confuse a 
user a lot. Isn't it valid
      just by returning EPERM will explain a lot to users saying that 
this is a snapshot of a
      subvolume or a parent subvolume which is not supposed to be 
deleted this way.

Regards

-- 
Harshavardhana
http://www.gluster.com

Re: ENOTEMPTY on "rm -rf" for snapshot and subvolume

[Chris Mason]

On Wed, Apr 07, 2010 at 05:44:20PM -0700, Harshavardhana wrote:
> Hi Everyone,
> 
>      Recently i created a snapshot of an existing volume which had
> some amount of data.
>      Now that after creating the snapshot i have tried deleting the
> same snapshot.  But i am
>      getting ENOTEMPTY for "rmdir". But when i see the actual files
> inside are deleted
>      not the parent directory.
> 
>      From the code it looks like
> 
>      if (inode->i_size > BTRFS_EMPTY_DIR_SIZE ||
>             inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
>                 return -ENOTEMPTY;
> 
>      Why would "unlink" succeeds for the files inside the
> directory?, yet returning ENOTEMPTY

You need to use the snapshot deletion ioctl to actually delete the
snapshot.

> 
>      This looks odd after this, i  went ahead and tried deleting the
> the existing volume itself
>      same result.
> 
>      So i was wondering if at all this is supposed to work this way,
> do i need to use "btrfs"
>      commands to delete subvolumes always? and their relative snapshots?.

Yes.  We could add support for doing this inside rm, it isn't a huge
amount of code.

> 
>      But either in that case too returning ENOTEMPTY does confuse a
> user a lot. Isn't it valid
>      just by returning EPERM will explain a lot to users saying that
> this is a snapshot of a
>      subvolume or a parent subvolume which is not supposed to be
> deleted this way.

Good point, eperm might be more intuitive.

-chris

Re: ENOTEMPTY on "rm -rf" for snapshot and subvolume

[Harshavardhana]

On 04/08/2010 06:52 AM, Chris Mason wrote:
>> >        But either in that case too returning ENOTEMPTY does confuse a
>> >  user a lot. Isn't it valid
>> >        just by returning EPERM will explain a lot to users saying that
>> >  this is a snapshot of a
>> >        subvolume or a parent subvolume which is not supposed to be
>> >  deleted this way.
>>      
> Good point, eperm might be more intuitive.
>
> -chris
>    
Thanks a lot for the inputs sent a patch for that.

Regards

-- 
Harshavardhana
http://www.gluster.com