struct drm_pagemap: Additional information for a struct dev_pagemap used for device p2p handshaking. @ops: The struct drm_pagemap_ops. Reference count. @drm: The struct drm device owning the device-private memory. @pagemap: Pointer to the underlying dev_pagemap. @dev_hold: Pointer to a struct drm_pagemap_dev_hold for device referencing. @cache: Back-pointer to the &struct drm_pagemap_cache used for this &struct drm_pagemap. May be NULL if no cache is used. @shrink_link: Link into the shrinker's list of drm_pagemaps. Only used if also using a pagemap cache.