Re: snapshot strange behaviour

[Lubos Kolouch <lubos.kolouch@gmail.com>]

Goffredo Baroncelli, Sun, 23 Jan 2011 13:17:13 +0100:

> Hi Lubos,
> 
> On 01/23/2011 08:17 AM, Lubos Kolouch wrote:
>> Hello,
>> 
>> During doing backups I found strange behaviour... 2.6.37, latest btrfs-
>> progs from git
>> 
>> nbgentoo ~ # btrfs subv crea a
>> Create subvolume './a'
>> nbgentoo ~ # cd a
>> nbgentoo a # btrfs subv crea b
>> Create subvolume './b'
>> nbgentoo a # touch b/file
>> nbgentoo a # ls -l b/
>> total 0
>> -rw-r--r-- 1 root root 0 Jan 23 08:14 file nbgentoo a # cd ..
>> nbgentoo ~ # btrfs subv snap a x
>> Create a snapshot of 'a' in './x'
>> nbgentoo ~ # ls -l x/b/
>> total 0
>> 
>> and also
>> 
>> nbgentoo ~ # cd x/
>> nbgentoo x # btrfs subv dele b
>> ERROR: 'b' is not a subvolume
>> 
>> Is this a bug or intended behaviour and I am missing something
>> something? How to snapshot a subvolume, containing another subvolumes?
> 
> It is the intended behavior. The snapshotting is not recursive about
> subvolumes. If you snapshot a subvolume which contains another one, you
> got only the content of the first subvolume. The directory "x/b" which
> you see, is not the subvolume "b" snapshotted, but only the
> "mount-point" of "b".
> 

Hi Goffredo,

I understand. But then I think btrfs should refuse to do it or at least 
print a warning. Otherwise it is very inconvenient for the user, having to
search for any subvolumes down the tree...

Lubos