From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3ty7tZ05kpzDqMB for ; Tue, 10 Jan 2017 08:43:01 +1100 (AEDT) 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> 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: MIME-Version: 1.0 Content-Type: text/plain List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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) {