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Message-ID: <5f758be455bb8f761d028ea078b3e2a618dfd4b1.camel@themaw.net>
Subject: Re: [LTP] [xfs] 73e5fff98b: kmsg.dev/zero:Can't_open_blockdev
From:   Ian Kent <raven@themaw.net>
To:     Christoph Hellwig <hch@lst.de>, Jan Stancek <jstancek@redhat.com>
Cc:     kernel test robot <rong.a.chen@intel.com>,
        "Darrick J. Wong" <darrick.wong@oracle.com>,
        LKML <linux-kernel@vger.kernel.org>, linux-xfs@vger.kernel.org,
        lkp@lists.01.org, ltp@lists.linux.it,
        DavidHowells <dhowells@redhat.com>,
        AlViro <viro@ZenIV.linux.org.uk>
Date:   Wed, 13 Nov 2019 09:13:22 +0800
In-Reply-To: <20191112120818.GA8858@lst.de>
References: <20191111010022.GH29418@shao2-debian>
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         <20191112120818.GA8858@lst.de>
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Adding Al and David to the CC, hopefully that will draw their
attention to this a bit sooner.

On Tue, 2019-11-12 at 13:08 +0100, Christoph Hellwig wrote:
> On Tue, Nov 12, 2019 at 07:02:23AM -0500, Jan Stancek wrote:
> > https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/fs/fs_fill/fs_fill.c
> > 
> > Setup of that test is trying different file system types, and it
> > looks
> > at errno code of "mount -t $fs /dev/zero /mnt/$fs".
> > 
> > Test still PASSes. This report appears to be only about extra
> > message in dmesg,
> > which wasn't there before:
> > 
> > # mount -t xfs /dev/zero /mnt/xfs

Assuming that is what is being done ...

> > # dmesg -c
> > [  897.177168] /dev/zero: Can't open blockdev
> 
> That message comes from fs/super.c:get_tree_bdev(), a common library
> used by all block device based file systems using the new mount API.

I'll have a look at get_tree_bdev() but when I compared mount_bdev()
to get_tree_bdev() before using it they looked like they did pretty
much the same thing.

I don't know how /dev/zero is meant to be handled, I'll need to try
and work that out if Al or David don't see this soon enough.

> 
> It doesn't seem all that useful to me, but it is something we'll
> need to discuss with David and Al, not the XFS maintainers.

Ian