From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751784AbcEAJfV (ORCPT ); Sun, 1 May 2016 05:35:21 -0400 Received: from mail-wm0-f49.google.com ([74.125.82.49]:35363 "EHLO mail-wm0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750893AbcEAJfS (ORCPT ); Sun, 1 May 2016 05:35:18 -0400 Message-ID: <5725CDD2.60904@plexistor.com> Date: Sun, 01 May 2016 12:35:14 +0300 From: Boaz Harrosh User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Toshi Kani , dan.j.williams@intel.com, david@fromorbit.com, jack@suse.cz CC: tytso@mit.edu, linux-nvdimm@ml01.01.org, linux-kernel@vger.kernel.org, adilger.kernel@dilger.ca, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 1/3] ext4: Add alignment check for DAX mount References: <1461962375-3720-1-git-send-email-toshi.kani@hpe.com> <1461962375-3720-2-git-send-email-toshi.kani@hpe.com> In-Reply-To: <1461962375-3720-2-git-send-email-toshi.kani@hpe.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/29/2016 11:39 PM, Toshi Kani wrote: > When a partition is not aligned by 4KB, mount -o dax succeeds, > but any read/write access to the filesystem fails, except for > metadata update. > > Add alignment check to ext4_fill_super() when -o dax is specified. > > Reported-by: Micah Parrish > Signed-off-by: Toshi Kani > Cc: "Theodore Ts'o" > Cc: Andreas Dilger > Cc: Jan Kara > Cc: Dan Williams > Cc: Ross Zwisler > --- > fs/ext4/super.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index 304c712..90a8670 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -3421,6 +3421,12 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) > "error: unsupported blocksize for dax"); > goto failed_mount; > } > + if (sb->s_bdev->bd_part->start_sect % (PAGE_SIZE / 512) || > + sb->s_bdev->bd_part->nr_sects % (PAGE_SIZE / 512)) { Can you please not do this like this? For me is a layering violation only the device should know what are its limits. I would prefer if you just try to bdev_direct_access() the 0 sector and if it fails then fail here. This way you let the device decide what it needs and if/how to support unaligned partitions. (For example it could by shrinking its size) Thanks Boaz > + ext4_msg(sb, KERN_ERR, > + "error: unaligned partition for dax"); > + goto failed_mount; > + } > if (!sb->s_bdev->bd_disk->fops->direct_access) { > ext4_msg(sb, KERN_ERR, > "error: device does not support dax"); > _______________________________________________ > Linux-nvdimm mailing list > Linux-nvdimm@lists.01.org > https://lists.01.org/mailman/listinfo/linux-nvdimm >