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rbd: Add support for smart cloning

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Added support for RBD PVC to PVC cloning, below
commands are executed to create a PVC-PVC clone from
RBD side.

* Check the depth(n) of the cloned image if n>=(hard limit -2)
or ((soft limit-2) Add a task to flatten the image and return
about (to avoid image leak) **Note** will try to flatten the
temp clone image in the chain if available
* Reserve the key and values in omap (this will help us to
avoid the leak as it's not reserved earlier as we have returned
ABORT (the request may not come back))
* Create a snapshot of rbd image
* Clone the snapshot (temp clone)
* Delete the snapshot
* Snapshot the temp clone
* Clone the snapshot (final clone)
* Delete the snapshot

```bash
1) check the image depth of the parent image if flatten required
add a task to flatten image and return ABORT to avoid leak
(hardlimit-2 and softlimit-2 check will be done)
2) Reserve omap keys
2) rbd snap create <RBD image for src k8s volume>@<random snap name>
3) 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>
4) rbd snap rm <RBD image for src k8s volume>@<random snap name>
5) rbd snap create <cloned RBD image created in snapshot process>@<random snap name>
6) 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>
7)rbd snap rm <RBD image for src k8s volume>@<random snap name>
```

* Delete temporary clone image created as part of clone(delete if present)
* Delete rbd image

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>
This commit is contained in:
Madhu Rajanna
2020-07-07 17:44:19 +05:30
committed by mergify[bot]
parent 9077c25c15
commit a0fd805a8b
8 changed files with 411 additions and 61 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
internal/rbd/rbd_journal.go
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@ -181,7 +181,7 @@ func checkSnapCloneExists(ctx context.Context, parentVol *rbdVolume, rbdSnap *rb
}
// check snapshot exists if not create it
_, err = vol.getSnapInfo(rbdSnap)
err = vol.checkSnapExists(rbdSnap)
var esnf ErrSnapNotFound
if errors.As(err, &esnf) {
// create snapshot
@ -223,12 +223,18 @@ func checkSnapCloneExists(ctx context.Context, parentVol *rbdVolume, rbdSnap *rb
/*
Check comment on checkSnapExists, to understand how this function behaves
**NOTE:** These functions manipulate the rados omaps that hold information regarding
volume names as requested by the CSI drivers. Hence, these need to be invoked only when the
respective CSI snapshot or volume name based locks are held, as otherwise racy access to these
omaps may end up leaving the omaps in an inconsistent state.
**NOTE:** These functions manipulate the rados omaps that hold information
regarding volume names as requested by the CSI drivers. Hence, these need to be
invoked only when the respective CSI snapshot or volume name based locks are
held, as otherwise racy access to these omaps may end up leaving the omaps in
an inconsistent state.
parentVol is required to check the clone is created from the requested parent
image or not, if temporary snapshots and clones created for the volume when the
content source is volume we need to recover from the stale entries or complete
the pending operations.
*/
func (rv *rbdVolume) Exists(ctx context.Context) (bool, error) {
func (rv *rbdVolume) Exists(ctx context.Context, parentVol *rbdVolume) (bool, error) {
err := validateRbdVol(rv)
if err != nil {
return false, err
@ -277,6 +283,16 @@ func (rv *rbdVolume) Exists(ctx context.Context) (bool, error) {
if err != nil {
var einf ErrImageNotFound
if errors.As(err, &einf) {
// Need to check cloned info here not on createvolume,
if parentVol != nil {
found, cErr := rv.checkCloneImage(ctx, parentVol)
if found && cErr == nil {
return true, nil
}
if cErr != nil {
return false, cErr
}
}
err = j.UndoReservation(ctx, rv.JournalPool, rv.Pool,
rv.RbdImageName, rv.RequestName)
return false, err