[PATCH] BLOCK: Stop fallback_migrate_page() from using page_has_buffers() [try #6]

Stop fallback_migrate_page() from using page_has_buffers() since that might not
be available.  Use PagePrivate() instead since that's more general.
Signed-Off-By: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

mm/migrate.c

@@ -525,7 +525,7 @@ static int fallback_migrate_page(struct address_space *mapping,
 	 * Buffers may be managed in a filesystem specific way.
 	 * We must have no buffers or drop them.
 	 */
-	if (page_has_buffers(page) &&
+	if (PagePrivate(page) &&
 	    !try_to_release_page(page, GFP_KERNEL))
 		return -EAGAIN;