mm, fs: remove remaining PAGE_CACHE_* and page_cache_{get,release} usage

Mostly direct substitution with occasional adjustment or removing
outdated comments.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index f396ccb..b3fc037 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -535,8 +535,7 @@
 /*
  * Fault a userspace page into pagetables.  Return non-zero on a fault.
  *
- * This assumes that two userspace pages are always sufficient.  That's
- * not true if PAGE_CACHE_SIZE > PAGE_SIZE.
+ * This assumes that two userspace pages are always sufficient.
  */
 static inline int fault_in_pages_writeable(char __user *uaddr, int size)
 {