On Wed, Mar 20, 2024 at 11:34 AM Anand Jain <anand.jain@xxxxxxxxxx> wrote:
>
> On 3/19/24 23:42, David Sterba wrote:
> > From: Josef Bacik <josef@xxxxxxxxxxxxxx>
> >
> > Btrfs has had the ability for almost a decade to allow ro and rw
> > mounting of subvols. This behavior specifically
> >
> > mount -o subvol=foo,ro /some/dir
> > mount -o subvol=bar,rw /some/other/dir
> >
> > This seems simple, but because of the limitations of how we did mounting
> > in ye olde days we would mark the super block as RO and the mount if we
> > mounted RO first. In the case above /some/dir would instantiate the
> > super block as read only and the mount point. So the second mount
> > command under the covers would convert the super block to RW, and then
> > allow the mount to continue.
> >
> > The results were still consistent, /some/dir was still read only because
> > the mount was marked read only, but /some/other/dir could be written to.
> >
> > This is a test to make sure we maintain this behavior, as I almost
> > regressed this behavior while converting us to the new mount API.
> >
> > Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
>
> looks good.
>
> Reviewed-by: Anand Jain <anand.jain@xxxxxxxxxx>
>
> Nits below.
>
> > ---
> > tests/btrfs/330 | 54 +++++++++++++++++++++++++++++++++++++++++++++
> > tests/btrfs/330.out | 6 +++++
> > 2 files changed, 60 insertions(+)
> > create mode 100755 tests/btrfs/330
> > create mode 100644 tests/btrfs/330.out
> >
> > diff --git a/tests/btrfs/330 b/tests/btrfs/330
> > new file mode 100755
> > index 00000000000000..3ce9840e76d028
> > --- /dev/null
> > +++ b/tests/btrfs/330
> > @@ -0,0 +1,54 @@
> > +#! /bin/bash
> > +# SPDX-License-Identifier: GPL-2.0
> > +# Copyright (c) 2023 Meta Platforms, Inc. All Rights Reserved.
> > +#
> > +# FS QA Test No. btrfs/330
> > +#
> > +# Test mounting one subvolume as ro and another as rw
> > +#
> > +. ./common/preamble
> > +_begin_fstest auto quick subvol
> > +
> > +_cleanup()
> > +{
> > + rm -rf $TEST_DIR/$seq
> > +}
> > +
> > +# Import common functions.
>
> > +. ./common/filter
>
> This can be deleted, as the filter.btrfs also calls the filter.
>
> > +. ./common/filter.btrfs
>
>
> > +
> > +# real QA test starts here
> > +_supported_fs btrfs
> > +_require_scratch
> > +
> > +$MOUNT_PROG -V | grep -q 'fd-based-mount'
> > +[ "$?" -eq 0 ] && _notrun "mount uses the new mount api"
> > +
> > +_scratch_mkfs > /dev/null 2>&1
>
> _scratch_mkfs >> $seqres.full
>
> Errors, if any, go to stdout.
We typically redirect stderr to stdout because in the past mkfs.btrfs
used to output to stderr a message when it performed trim.
See this old commit:
https://git.kernel.org/pub/scm/fs/xfs/xfstests-dev.git/commit/?id=afadb6e5958c5acf2425d6a8a9372b63afcb4f2a
And nowadays we're encouraged to do:
_scratch_mkfs >> $seqres.full 2>&1 || _fail "mkfs failed"
So in case mkfs fails the test doesn't continue and silently passes by
using the filesystem SCRATCH_MNT belongs to.
This has been discussed and pointed out several times, but I don't
have a link to such discussion.
>
> Thanks, Anand
>
> > +_scratch_mount
> > +
> > +# Create our subvolumes to mount
> > +$BTRFS_UTIL_PROG subvolume create $SCRATCH_MNT/foo | _filter_scratch
> > +$BTRFS_UTIL_PROG subvolume create $SCRATCH_MNT/bar | _filter_scratch
> > +
> > +_scratch_unmount
> > +
> > +mkdir -p $TEST_DIR/$seq/foo
> > +mkdir -p $TEST_DIR/$seq/bar
> > +
> > +_mount -t btrfs -o subvol=foo,ro $SCRATCH_DEV $TEST_DIR/$seq/foo
> > +_mount -t btrfs -o subvol=bar,rw $SCRATCH_DEV $TEST_DIR/$seq/bar
> > +
> > +echo "making sure foo is read only"
> > +touch $TEST_DIR/$seq/foo/baz > /dev/null 2&>1
> > +ls $TEST_DIR/$seq/foo
> > +
> > +echo "making sure bar allows writes"
> > +touch $TEST_DIR/$seq/bar/qux
> > +ls $TEST_DIR/$seq/bar
> > +
> > +$UMOUNT_PROG $TEST_DIR/$seq/foo
> > +$UMOUNT_PROG $TEST_DIR/$seq/bar
> > +
> > +status=0 ; exit
> > diff --git a/tests/btrfs/330.out b/tests/btrfs/330.out
> > new file mode 100644
> > index 00000000000000..4795a2ccc8cb62
> > --- /dev/null
> > +++ b/tests/btrfs/330.out
> > @@ -0,0 +1,6 @@
> > +QA output created by 330
> > +Create subvolume 'SCRATCH_MNT/foo'
> > +Create subvolume 'SCRATCH_MNT/bar'
> > +making sure foo is read only
> > +making sure bar allows writes
> > +qux
>
>
