Retrieve pages from block ContentReference

Is it possible to retrieve pages that uses a shared block instance in EPIserver 7.

You can use ContentSoftLinkRepository to get references to/from the content item. Let's say blockLink is the content reference of your block.

// resolving the repository. It can also be injected as a property or in your constructor.
var linkRepository = ServiceLocator.Current.GetInstance<ContentSoftLinkRepository>();

// loading soft links for your block
var referencingContentLinks = linkRepository.Load(blockLink, true).Where(link =>
                    link.SoftLinkType == ReferenceType.PageLinkReference &&
                    !ContentReference.IsNullOrEmpty(link.OwnerContentLink))
                .Select(link => link.OwnerContentLink)
                .ToList();

Now you have the list of content links of pages/blocks/... that uses/references your block.