This Adds a support for create,delete snapshot
and creating a new rbd image from the snapshot.
* Create a snapshot
* Create a temporary snapshot from the parent volume
* Clone a new image from a temporary snapshot with options
--rbd-default-clone-format 2 --image-feature layering,deep-flatten
* Delete temporary snapshot created
* Create a new snapshot from cloned image
* Check the image chain depth, if the Softlimit is reached Add a
task Flatten the cloned image and return success. if the depth
is reached hard limit Add a task Flatten the cloned image and
return snapshot status ready as false
```bash
1) rbd snap create <RBD image for src k8s volume>@<random snap name>
2) rbd clone --rbd-default-clone-format 2 --image-feature
layering,deep-flatten <RBD image for src k8s volume>@<random snap>
<RBD image for temporary snap image>
3) rbd snap rm <RBD image for src k8s volume>@<random snap name>
4) rbd snap rm <RBD image for temporary snap image>@<random snap name>
5) check the depth, if the depth is greater than configured hard
limit add a task to flatten the cloned image return snapshot status
ready as false if the depth is greater than soft limit add a task
to flatten the image and return success
```
* Create a clone from snapshot
* Clone a new image from the snapshot with user-provided options
* Check the depth(n) of the cloned image if n>=(hard limit)
Add task to flatten the image and return ABORT (to avoid image leak)
```bash
1) rbd clone --rbd-default-clone-format 2 --image-feature
<k8s dst vol config> <RBD image for temporary snap image>@<random snap name>
<RBD image for k8s dst vol>
2) check the depth, if the depth is greater than configured hard limit
add a task to flatten the cloned image return ABORT error if the depth is
greater than soft limit add a task to flatten the image and return success
```
* Delete snapshot or pvc
* Move the temporary cloned image to the trash
* Add task to remove the image from the trash
```bash
1) rbd trash mv <cloned image>
2) ceph rbd task trash remove <cloned image>
```
With earlier implementation to delete the image, we used to add
a task to remove the image with new changes this cannot be done
as the image may contain snapshots or linking.so we will be
doing below steps to delete an image(this will be
applicable for both normal image and cloned image)
* Move the rbd image to the trash
* Add task to remove the image from the trash
```bash
1) rbd trash mv <image>
2) ceph rbd task trash remove <image>
```
Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>
