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rbd: pass a max-depth to getCloneDepth()
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The `getCloneDepth()` function does not need to traverse the whole chain
of parents when a certain max-limit is configured. The traversing can be
aborted once the hard-limit is reached. This makes the procedure a
little more efficient, as unnecessary traversing is prevented.

Signed-off-by: Niels de Vos <ndevos@ibm.com>
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nixpanic committed Nov 27, 2023
1 parent 332b475 commit 373c670
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Showing 2 changed files with 13 additions and 4 deletions.
2 changes: 1 addition & 1 deletion internal/rbd/nodeserver.go
Original file line number Diff line number Diff line change
Expand Up @@ -595,7 +595,7 @@ func flattenImageBeforeMapping(
if err != nil {
return err
}
depth, err = volOptions.getCloneDepth()
depth, err = volOptions.getCloneDepth(rbdHardMaxCloneDepth + 1)
if err != nil {
return err
}
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15 changes: 12 additions & 3 deletions internal/rbd/rbd_util.go
Original file line number Diff line number Diff line change
Expand Up @@ -707,11 +707,13 @@ func (ri *rbdImage) trashRemoveImage(ctx context.Context) error {
}

// getCloneDepth walks the parents of the image and returns the number of
// images in the chain.
// images in the chain. The `max` argument to the function is used to specify a
// limit of the depth to check. When `max` depth is reached, no further
// traversing of the depth is required.
//
// This function re-uses the ioctx of the image to open all images in the
// chain. There is no need to open new ioctx's for every image.
func (ri *rbdImage) getCloneDepth() (uint, error) {
func (ri *rbdImage) getCloneDepth(max uint) (uint, error) {
var (
depth uint
info *librbd.ParentInfo
Expand Down Expand Up @@ -741,6 +743,13 @@ func (ri *rbdImage) getCloneDepth() (uint, error) {
// if there is a parent, count it to the depth
depth++

// if max (usually hard-limit) is reached, further traversing
// parents is not needed, some action (flattening) will be
// triggered regardless of deeper depth
if depth == max {
break
}

// open the parent image, so that the for-loop can continue
// with checking for the parent of the parent
image, err = librbd.OpenImageById(ri.ioctx, info.Image.ImageID, info.Snap.SnapName)
Expand Down Expand Up @@ -830,7 +839,7 @@ func (ri *rbdImage) flattenRbdImage(

// skip clone depth check if request is for force flatten
if !forceFlatten {
depth, err = ri.getCloneDepth()
depth, err = ri.getCloneDepth(hardlimit)
if err != nil {
return err
}
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