Re: [PATCH v2] sheepdog: reject snapshot as a LUN to avoid deleting working VDI

On Fri, 14 Oct 2016 14:20:48 +0900
Hitoshi Mitake <[email protected]> wrote:

> On Thu, Oct 13, 2016 at 9:02 PM, Takashi Menjo
> <[email protected]> wrote:
>> This commit lets the sheepdog driver reject forms of filename below.
>> This is to avoid unintended deletion of working VDI when a snapshot is
>> given as a LUN.
>>
>>  * unix:<path_of_unix_domain_socket>:<vdi>:<tag>
>>  * unix:<path_of_unix_domain_socket>:<vdi>:<snapid>
>>  * tcp:<host>:<port>:<vdi>:<tag>
>>  * tcp:<host>:<port>:<vdi>:<snapid>
>>
>> In the case that a snapshot is given as a LUN by any of them above, the
>> sheepdog driver attempts to delete it then create a new writable VDI when
>> some data is being written to it. The deletion request contains name and
>> VDI ID of the snapshot. However, sheep daemon uses its name but ignores
>> VDI ID and, what is worse, the request contains neither snapshot ID nor
>> tag. So sheep daemon receiving the request interprets it as deletion of
>> working VDI, not snapshot. If there is working VDI with the same name,
>> it will be deleted unintentionally.
>>
>> I decided not to fix the sheepdog driver to send snapshot ID or tag but
>> to let it reject snapshot as a LUN because, even if I fix it, creating
>> a new writable VDI will be failed when working VDI exists. If you want
>> workaround, use "dog vdi clone" command to create a new writable VDI from
>> snapshot then give the new VDI as a LUN.
>>
>> Cc: Teruaki Ishizaki <[email protected]>
>> Cc: Hitoshi Mitake <[email protected]>
>> Signed-off-by: Takashi Menjo <[email protected]>
>> ---
>>  usr/bs_sheepdog.c | 112 +-----------------------------------------------------
>>  1 file changed, 2 insertions(+), 110 deletions(-)
> 
> Acked-by: Hitoshi Mitake <[email protected]>

Applied, thanks guys.