+/*
+ * Adjust the dirty region of the page on truncation or full invalidation,
+ * getting rid of the markers altogether if the region is entirely invalidated.
+ */
+static void afs_invalidate_dirty(struct page *page, unsigned int offset,
+ unsigned int length)
+{
+ struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
+ unsigned long priv;
+ unsigned int f, t, end = offset + length;
+
+ priv = page_private(page);
+
+ /* we clean up only if the entire page is being invalidated */
+ if (offset == 0 && length == thp_size(page))
+ goto full_invalidate;
+
+ /* If the page was dirtied by page_mkwrite(), the PTE stays writable
+ * and we don't get another notification to tell us to expand it
+ * again.
+ */
+ if (afs_is_page_dirty_mmapped(priv))
+ return;
+
+ /* We may need to shorten the dirty region */
+ f = afs_page_dirty_from(priv);
+ t = afs_page_dirty_to(priv);
+
+ if (t <= offset || f >= end)
+ return; /* Doesn't overlap */
+
+ if (f < offset && t > end)
+ return; /* Splits the dirty region - just absorb it */
+
+ if (f >= offset && t <= end)
+ goto undirty;
+
+ if (f < offset)
+ t = offset;
+ else
+ f = end;
+ if (f == t)
+ goto undirty;
+
+ priv = afs_page_dirty(f, t);
+ set_page_private(page, priv);
+ trace_afs_page_dirty(vnode, tracepoint_string("trunc"), page->index, priv);
+ return;
+
+undirty:
+ trace_afs_page_dirty(vnode, tracepoint_string("undirty"), page->index, priv);
+ clear_page_dirty_for_io(page);
+full_invalidate:
+ priv = (unsigned long)detach_page_private(page);
+ trace_afs_page_dirty(vnode, tracepoint_string("inval"), page->index, priv);
+}
+