On Thu, Apr 12, 2018 at 10:23 AM, handong He <hedongho@xxxxxxxxx> wrote:
> Hi, cephers:
>
> I did some test about rbd cli operation and have some doubt.
>
> 1. rbd can be removed during copy operation. And both 'cp' and
> 'rm' command return success. However the dest-image data is diff from
> the src-image.
> why not set a watcher for the rbd_header obj for the opening
> image. So it will occur error and return image ebusy when run 'rm'.
>
> easy to reproduce:
> 1. rbd cp rbd/img0 rbd/img1
> 2. while cp is runing, exec: rbd rm rbd/img0
> 3. after finish, just compare two img's du(USED): rbd du rbd/img1
>
> 2. in krbd, image-feature should be only set 'layering' for the
> 'map' operation.But for clone image: the child img set layering, but
> parent img has more feature that krbd not support. it will fail while
> child img exec ' rbd map'.
> i think it is logical, but maybe a little complex while the
> chain is long. we have to lookup every ancestors and make sure their
> feature is match krbd's support features. will that be any optimize?
>
> easy to reproduce:
> 1. rbd clone rbd/img0@sn1 rbd/img1 --image-feature=layering
> 2. parent img0 has default feature, which make 'rbd map
> rbd/img1' failed.
The entire parent chain has to be traversed during "rbd map" to set up
in-core data structures for each parent image and link them together.
Checking the feature bits is just one of the steps, so I don't see any
optimization opportunities here.
Thanks,
Ilya
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