From patchwork Thu Jan 21 03:36:44 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ross Zwisler X-Patchwork-Id: 8077211 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 01F529F440 for ; Thu, 21 Jan 2016 03:38:00 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 27AFA204AE for ; Thu, 21 Jan 2016 03:37:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2C87B20392 for ; Thu, 21 Jan 2016 03:37:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756471AbcAUDhF (ORCPT ); Wed, 20 Jan 2016 22:37:05 -0500 Received: from mga09.intel.com ([134.134.136.24]:36772 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752651AbcAUDhE (ORCPT ); Wed, 20 Jan 2016 22:37:04 -0500 Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga102.jf.intel.com with ESMTP; 20 Jan 2016 19:37:02 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,324,1449561600"; d="scan'208";a="895092784" Received: from jbanerje-mobl.amr.corp.intel.com (HELO phyrexia.intel.com) ([10.254.81.91]) by orsmga002.jf.intel.com with ESMTP; 20 Jan 2016 19:37:02 -0800 From: Ross Zwisler To: linux-kernel@vger.kernel.org Cc: Ross Zwisler , Alexander Viro , Andrew Morton , Dan Williams , Dave Chinner , Jan Kara , Matthew Wilcox , linux-fsdevel@vger.kernel.org, linux-nvdimm@lists.01.org Subject: [PATCH 1/5] dax: never rely on bh.b_dev being set by get_block() Date: Wed, 20 Jan 2016 20:36:44 -0700 Message-Id: <1453347408-22830-2-git-send-email-ross.zwisler@linux.intel.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1453347408-22830-1-git-send-email-ross.zwisler@linux.intel.com> References: <1453347408-22830-1-git-send-email-ross.zwisler@linux.intel.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Previously in DAX we assumed that calls to get_block() would set bh.b_bdev, and we would then use that value even in error cases for debugging. This caused a NULL pointer dereference in __dax_dbg() which was fixed by a previous commit, but that commit only changed the one place where we were hitting an error. Instead, update dax.c so that we always initialize bh.b_bdev as best we can based on the information that DAX has. get_block() may or may not update to a new value, but this at least lets us get something helpful from bh.b_bdev for error messages and not have to worry about whether it was set by get_block() or not. Signed-off-by: Ross Zwisler Reported-by: Jan Kara --- fs/dax.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/dax.c b/fs/dax.c index 0db21ea..cee9e1b 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -246,6 +246,7 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode, loff_t end = pos + iov_iter_count(iter); memset(&bh, 0, sizeof(bh)); + bh.b_bdev = inode->i_sb->s_bdev; if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ) { struct address_space *mapping = inode->i_mapping; @@ -582,6 +583,7 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, memset(&bh, 0, sizeof(bh)); block = (sector_t)vmf->pgoff << (PAGE_SHIFT - blkbits); + bh.b_bdev = inode->i_sb->s_bdev; bh.b_size = PAGE_SIZE; repeat: @@ -1018,6 +1020,7 @@ int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length, BUG_ON((offset + length) > PAGE_CACHE_SIZE); memset(&bh, 0, sizeof(bh)); + bh.b_bdev = inode->i_sb->s_bdev; bh.b_size = PAGE_CACHE_SIZE; err = get_block(inode, index, &bh, 0); if (err < 0)