ceph: Remove bogus check in invalidatepage

The early bug checks are moot because the VMA layer ensures those things.

1. It will not call invalidatepage unless PagePrivate (or PagePrivate2) are set
2. It will not call invalidatepage without taking a PageLock first.
3. Guantrees that the inode page is mapped.
Signed-off-by: NMilosz Tanski <milosz@adfin.com>
Reviewed-by: NSage Weil <sage@inktank.com>

fs/ceph/addr.c

@@ -149,10 +149,6 @@ static void ceph_invalidatepage(struct page *page, unsigned long offset)
 	struct ceph_inode_info *ci;
 	struct ceph_snap_context *snapc = page_snap_context(page);
 
-	BUG_ON(!PageLocked(page));
-	BUG_ON(!PagePrivate(page));
-	BUG_ON(!page->mapping);
-
 	inode = page->mapping->host;
 
 	/*