Re: [PATCH] xfstests: test EROFS vs. EEXIST when creating on an RO filesystem

Dave Chinner
2012-11-27T22:05:51Z

On Tue, Nov 27, 2012 at 03:16:39PM -0600, Eric Sandeen wrote:
> TBH, I don't know if this is posix-specified, but I found out the
> hard way that when trying to re-create existing files on a readonly
> filesystem, some apps expect/handle EEXIST, but fail on EROFS.
>
> This will test mkdir, mknod, and symlinks for that behavior.
>
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
>
> Note: Think the command output is fixed enough, or should I
> be grepping for keywords?

Command output is good enough at this point.

>
> diff --git a/292 b/292
> new file mode 100755
> index 0000000..a14bb7f
> --- /dev/null
> +++ b/292
> @@ -0,0 +1,73 @@
> +#! /bin/bash
> +# FS QA Test No. 292
> +#
> +# Tests for EEXIST (not EROFS) for inode creations, if
> +# we ask to create an already-existing entity on an RO filesystem
> +#
> +#-----------------------------------------------------------------------
> +# Copyright (c) 2012 Red Hat, Inc. All Rights Reserved.
> +#
> +# This program is free software; you can redistribute it and/or
> +# modify it under the terms of the GNU General Public License as
> +# published by the Free Software Foundation.
> +#
> +# This program is distributed in the hope that it would be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program; if not, write the Free Software Foundation,
> +# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
> +#-----------------------------------------------------------------------
> +#
> +# creator
> +owner=sandeen@redhat.com
> +
> +seq=`basename $0`
> +echo "QA output created by $seq"
> +
> +here=`pwd`
> +tmp=/tmp/$$
> +status=1 # failure is the default!
> +trap "_cleanup; exit \$status" 0 1 2 3 15
> +
> +_cleanup()
> +{
> + cd /
> + rm -f $tmp.*
> +}
> +
> +# get standard environment, filters and checks
> +. ./common.rc
> +. ./common.filter
> +
> +# real QA test starts here
> +
> +# Modify as appropriate.
> +_supported_fs generic
> +_supported_os Linux
> +_require_scratch
> +
> +THIS_TEST_DIR=$SCRATCH_MNT/$seq.test

Confusing. $TEST_DIR is test filesystem mount point. This points
something very similarly names at the scratch filesystem....

> +_create_files()
> +{
> + mknod $THIS_TEST_DIR/testnode c 1 3
> + mkdir $THIS_TEST_DIR/testdir
> + touch $THIS_TEST_DIR/testtarget
> + ln -s $THIS_TEST_DIR/testtarget $THIS_TEST_DIR/testlink
> +}
> +
> +_scratch_mount

You need to mkfs the scratch device before using it. There is no
guarantee that it is inmountable shape, or even contains the right
filesytsem type when the test starts.

> +
> +rm -rf $THIS_TEST_DIR
> +mkdir $THIS_TEST_DIR || _fail "Could not create dir for test"

The error will dump into the output file and fail the golden output
match. Using _fail means there's no .out.bad file for analysis of
the failure.

> +
> +_create_files 2>&1 | _filter_scratch
> +_scratch_mount -o remount,ro || _fail "Could not remount scratch readonly"

Ditto.

Otherwise looks OK.

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com