[sheepdog] [PATCH 1/2] collie: add command 'collie vdi rollback'

[MORITA Kazutaka]

At Fri, 31 Aug 2012 14:25:04 +0800,
levin li wrote:
> 
> On 08/31/2012 02:10 PM, MORITA Kazutaka wrote:
> > At Fri, 31 Aug 2012 13:53:29 +0800,
> > levin li wrote:
> >>
> >> On 08/31/2012 12:17 PM, MORITA Kazutaka wrote:
> >>> At Thu, 30 Aug 2012 13:59:54 +0800,
> >>> levin li wrote:
> >>>>
> >>>> From: levin li <xingke.lwp at taobao.com>
> >>>>
> >>>> With this command we can rollback a cloned VDI to any specified
> >>>> snapshot, or easily reset to its parent VDI, the usage is easy.
> >>>>
> >>>> To rollback to a specified snapshot:
> >>>>
> >>>> $ collie vdi rollback -s 1 base_vdi clone_vdi
> >>>
> >>> Do we need to go back to a snapshot of another vdi?
> >>>
> >>> What I thought was like follows:
> >>>
> >>>   $ collie vdi rollback -h
> >>>   Usage: collie vdi check [-s snapshot] <vdiname>
> >>>
> >>>   $ collie vdi create test 4G
> >>>   $ collie vdi snapshot test -s snap1
> >>>   $ collie vdi snapshot test -s snap2
> >>>   $ collie vdi tree test
> >>>   test---[2012-08-31 13:05]---[2012-08-31 13:06]---(you are here)
> >>>   $ collie vdi list test
> >>>     Name        Id    Size    Used  Shared    Creation time   VDI id  Copies  Tag
> >>>   s test         1  4.0 GB  0.0 MB  0.0 MB 2012-08-31 13:05   7c2b25     1         snap1
> >>>   s test         2  4.0 GB  0.0 MB  0.0 MB 2012-08-31 13:06   7c2b26     1         snap2
> >>>     test         3  4.0 GB  0.0 MB  0.0 MB 2012-08-31 13:07   7c2b27     1              
> >>>
> >>>   $ collie vdi rollback test -s snap1
> >>>   $ collie vdi tree test
> >>>   test---[2012-08-31 13:05]-+-[2012-08-31 13:06]---[2012-08-31 13:07]
> >>>                             `-(you are here)
> >>>   $ collie vdi list test
> >>>     Name        Id    Size    Used  Shared    Creation time   VDI id  Copies  Tag
> >>>   s test         1  4.0 GB  0.0 MB  0.0 MB 2012-08-31 13:05   7c2b25     1         snap1
> >>>   s test         2  4.0 GB  0.0 MB  0.0 MB 2012-08-31 13:06   7c2b26     1         snap2
> >>>   s test         3  4.0 GB  0.0 MB  0.0 MB 2012-08-31 13:07   7c2b27     1              
> >>>     test         4  4.0 GB  4.0 MB  0.0 MB 2012-08-31 13:08   7c2b28     1              
> >>>
> >>>
> >>> Thanks,
> >>>
> >>> Kazutaka
> >>>
> >>
> >> Maybe I misunderstood you, but this patch can do more than you expected,
> >> it's no harm for users to rollback a VDI to any snapshot if they choose to.
> > 
> > I've tried, but it doesn't work well.
> > 
> > $ collie vdi create test 4G
> > $ collie vdi snapshot test -s snap1
> > $ collie vdi snapshot test -s snap2
> > $ collie vdi rollback test -s snap1  <- Can you support this usage?
> > Segmentation fault                   <- Please fix this
> > $ collie vdi rollback test test -s snap1
> > Can not rollback a non-cloned VDI    <- We want to a rollback command even if
> >                                         the vdi is not a cloned one
> > 
> > Thanks,
> > 
> > Kazutaka
> > 
> 
> I'll fix the segment fault, but it doesn't support the usage like this:
> 
> $ collie vdi rollback test -s snap1

Please support it.  This is the usage most users would imagine, I
think.

> 
> We must specify the dest name.
> 
> I make it only handle the rollback for cloned VDI now, how can we rollback
> a snapshot? it may destroys the VDI tree structure.

Adding a new child to the snapshot like creating a clone does not
work?

Thanks,

Kazutaka