From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751895AbdKVCXp (ORCPT ); Tue, 21 Nov 2017 21:23:45 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:56717 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752018AbdKVCUf (ORCPT ); Tue, 21 Nov 2017 21:20:35 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Shaohua Li" , "Zhilong Liu" , "NeilBrown" Date: Wed, 22 Nov 2017 01:58:13 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 076/133] md/bitmap: disable bitmap_resize for file-backed bitmaps. In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.51-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: NeilBrown commit e8a27f836f165c26f867ece7f31eb5c811692319 upstream. bitmap_resize() does not work for file-backed bitmaps. The buffer_heads are allocated and initialized when the bitmap is read from the file, but resize doesn't read from the file, it loads from the internal bitmap. When it comes time to write the new bitmap, the bh is non-existent and we crash. The common case when growing an array involves making the array larger, and that normally means making the bitmap larger. Doing that inside the kernel is possible, but would need more code. It is probably easier to require people who use file-backed bitmaps to remove them and re-add after a reshape. So this patch disables the resizing of arrays which have file-backed bitmaps. This is better than crashing. Reported-by: Zhilong Liu Fixes: d60b479d177a ("md/bitmap: add bitmap_resize function to allow bitmap resizing.") Signed-off-by: NeilBrown Signed-off-by: Shaohua Li Signed-off-by: Ben Hutchings --- drivers/md/bitmap.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/drivers/md/bitmap.c +++ b/drivers/md/bitmap.c @@ -1802,6 +1802,11 @@ int bitmap_resize(struct bitmap *bitmap, long pages; struct bitmap_page *new_bp; + if (bitmap->storage.file && !init) { + pr_info("md: cannot resize file-based bitmap\n"); + return -EINVAL; + } + if (chunksize == 0) { /* If there is enough space, leave the chunk size unchanged, * else increase by factor of two until there is enough space.