From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933537AbdAIVnE (ORCPT ); Mon, 9 Jan 2017 16:43:04 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48238 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750978AbdAIVm7 (ORCPT ); Mon, 9 Jan 2017 16:42:59 -0500 From: Jeff Moyer To: axboe@kernel.dk, Chandan Rajendra Cc: jack@suse.cz, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, anton@samba.org, linuxppc-dev@lists.ozlabs.org Subject: [PATCH] direct-io: don't introduce another read of inode->i_blkbits References: <1483886830-23878-1-git-send-email-chandan@linux.vnet.ibm.com> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Mon, 09 Jan 2017 16:42:58 -0500 In-Reply-To: <1483886830-23878-1-git-send-email-chandan@linux.vnet.ibm.com> (Chandan Rajendra's message of "Sun, 8 Jan 2017 20:17:10 +0530") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Mon, 09 Jan 2017 21:43:00 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 20ce44d545844 ("do_direct_IO: Use inode->i_blkbits to compute block count to be cleaned") introduced a regression: if the block size of the block device is changed while a direct I/O request is being setup, it can result in a panic. See commit ab73857e354ab ("direct-io: don't read inode->i_blkbits multiple times") for the reasoning, and commit b87570f5d3496 ("Fix a crash when block device is read and block size is changed at the same time") for a more detailed problem description and reproducer. Fixes: 20ce44d545844 Signed-off-by: Jeff Moyer --- Chandan, can you please test this to ensure this still fixes your problem? diff --git a/fs/direct-io.c b/fs/direct-io.c index b20adf9..c87bae4 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -905,8 +905,8 @@ static inline void dio_zero_block(struct dio *dio, struct dio_submit *sdio, static int do_direct_IO(struct dio *dio, struct dio_submit *sdio, struct buffer_head *map_bh) { - const unsigned i_blkbits = dio->inode->i_blkbits; const unsigned blkbits = sdio->blkbits; + const unsigned i_blkbits = blkbits + sdio->blkfactor; int ret = 0; while (sdio->block_in_file < sdio->final_block_in_request) {