incusd/storage/lvm: Discard the new blocks on resize

Suggested-by: Takero Funaki <[email protected]>
Signed-off-by: Stéphane Graber <[email protected]>

Author: stgraber

internal/server/storage/drivers/driver_lvm_utils.go

@@ -573,6 +573,22 @@ func (d *lvm) resizeLogicalVolume(lvPath string, sizeBytes int64) error {
 		return err
 	}
 
+	// On thick pools, discard the blocks in the additional space when the volume is grown.
+	if !d.usesThinpool() {
+		oldSizeBytes, err := d.logicalVolumeSize(lvPath)
+		if err != nil {
+			return err
+		}
+
+		if oldSizeBytes < sizeBytes {
+			// Discard the new blocks.
+			err := linux.ClearBlock(lvPath, sizeBytes)
+			if err != nil {
+				return err
+			}
+		}
+	}
+
 	d.logger.Debug("Logical volume resized", logger.Ctx{"dev": lvPath, "size": fmt.Sprintf("%db", sizeBytes)})
 	return nil
 }