[Intel-gfx] [PATCH 0/2 v2] drm/i915: mark GEM objects as dirtied by CPU

[Dave Gordon]

This patchset covers various places where GEM objects are dirtied by
means of CPU writes.

The first patch covers cases where only one page is actually written;
here we can mark just the specific page in the pagecache dirty. This
applies to regular (shmfs-backed) objects only.

The second patch covers situations where a subrange that is not limited
to a single page is modified, or a whole object is filled with data via
CPU writes. In either case, the object is now dirty (i.e. backing store
is out-of-date w.r.t. current contents) and must be marked so or risk
losing its contents if evicted. For the whole-object cases, marking the
individual pages at the point of writing would not be a win; instead
put_pages() will propagate the object-dirty flag to each page iff the
object is ever evicted.