From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759802AbcAURq0 (ORCPT ); Thu, 21 Jan 2016 12:46:26 -0500 Received: from mga04.intel.com ([192.55.52.120]:60010 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965592AbcAURqW (ORCPT ); Thu, 21 Jan 2016 12:46:22 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,326,1449561600"; d="scan'208";a="637950056" 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@ml01.01.org Subject: [PATCH v2 1/5] dax: never rely on bh.b_dev being set by get_block() Date: Thu, 21 Jan 2016 10:46:00 -0700 Message-Id: <1453398364-22537-2-git-send-email-ross.zwisler@linux.intel.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1453398364-22537-1-git-send-email-ross.zwisler@linux.intel.com> References: <1453398364-22537-1-git-send-email-ross.zwisler@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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) -- 2.5.0