ceph: check folio PG_private bit instead of folio->private

The pages in the file mapping maybe reclaimed and reused by other
subsystems and the page->private maybe used as flags field or
something else, if later that pages are used by page caches again
the page->private maybe not cleared as expected.

Here will check the PG_private bit instead of the folio->private.

Cc: stable@vger.kernel.org
URL: https://tracker.ceph.com/issues/55421
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Luis Henriques <lhenriques@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/addr.c

@@ -85,7 +85,7 @@ static bool ceph_dirty_folio(struct address_space *mapping, struct folio *folio)
 	if (folio_test_dirty(folio)) {
 		dout("%p dirty_folio %p idx %lu -- already dirty\n",
 		     mapping->host, folio, folio->index);
-		BUG_ON(!folio_get_private(folio));
+		VM_BUG_ON_FOLIO(!folio_test_private(folio), folio);
 		return false;
 	}
 
@@ -122,7 +122,7 @@ static bool ceph_dirty_folio(struct address_space *mapping, struct folio *folio)
 	 * Reference snap context in folio->private.  Also set
 	 * PagePrivate so that we get invalidate_folio callback.
 	 */
-	BUG_ON(folio_get_private(folio));
+	VM_BUG_ON_FOLIO(folio_test_private(folio), folio);
 	folio_attach_private(folio, snapc);
 
 	return ceph_fscache_dirty_folio(mapping, folio);
@@ -150,7 +150,7 @@ static void ceph_invalidate_folio(struct folio *folio, size_t offset,
 	}
 
 	WARN_ON(!folio_test_locked(folio));
-	if (folio_get_private(folio)) {
+	if (folio_test_private(folio)) {
 		dout("%p invalidate_folio idx %lu full dirty page\n",
 		     inode, folio->index);
 
@@ -729,8 +729,11 @@ static void writepages_finish(struct ceph_osd_request *req)
 
 	/* clean all pages */
 	for (i = 0; i < req->r_num_ops; i++) {
-		if (req->r_ops[i].op != CEPH_OSD_OP_WRITE)
+		if (req->r_ops[i].op != CEPH_OSD_OP_WRITE) {
+			pr_warn("%s incorrect op %d req %p index %d tid %llu\n",
+				__func__, req->r_ops[i].op, req, i, req->r_tid);
 			break;
+		}
 
 		osd_data = osd_req_op_extent_osd_data(req, i);
 		BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_PAGES);