Re: btrfs subvolume snapshot syntax too "smart"

[Freddie Cash <fjwcash@gmail.com>]

On Mon, Apr 4, 2011 at 12:47 PM, Goffredo Baroncelli <kreijack@libero.i=
t> wrote:
> On 04/04/2011 09:09 PM, krzf83@gmail.com wrote:
>> I understand btrfs intent but same command run twice should not give
>> diffrent results. This really makes snapshot automation hard
>>
>>
>> root@sv12 [/ssd]# btrfs subvolume snapshot /ssd/sub1 /ssd/5
>> Create a snapshot of '/ssd/sub1' in '/ssd/5'
>> root@sv12 [/ssd]# btrfs subvolume snapshot /ssd/sub1 /ssd/5
>> Create a snapshot of '/ssd/sub1' in '/ssd/5/sub1'
>> root@sv12 [/ssd]# btrfs subvolume snapshot /ssd/sub1 /ssd/5
>> Create a snapshot of '/ssd/sub1' in '/ssd/5/sub1'
>> ERROR: cannot snapshot '/ssd/sub1'
>
> The same is true for cp:
>
> # cp -rf /ssd/sub1 /ssd/5 =C2=A0 =C2=A0 =C2=A0 -> copy "sub1" as "5"
> # cp -rf /ssd/sub1 /ssd/5 =C2=A0 =C2=A0 =C2=A0 -> copy "sub1" in "5"
>
> However you are right. It could be fixed easily adding a switch like
> "--script", which force to handle the last part of the destination as
> the name of the subvolume, raising an error if it already exists.
>
> "subvolume snapshot" is the only command which suffers of this kind o=
f
> problem ?

Isn't this a situation where supporting a trailing / would help?

=46or example, with the / at the end, means "put the snapshot into the
folder".  Thus "btrfs subvolume snapshot /ssd/sub1 /ssd/5/" would
create a "sub1" snapshot inside the 5/ folder.  Running it a second
time would error out since /ssd/5/sub1/ already exists.  And if the 5/
folder doesn't exist, it would error out.

And without the / at the end, means "name the snapshot".  Thus "btrfs
subvolume snapshot /ssd/sub1 /ssd/5" would create a snapshot named
"/ssd/5".  Running the command again would error out due to the
snapshot already existing.  And if the 5/ folder doesn't exist, it's
created.  And it errors out if the 5/ folder already exists.

Or, something along those lines.  Similar to how other apps work
with/without a trailing /.

--=20
=46reddie Cash
fjwcash@gmail.com
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