Re: [PATCH] btrfs/022: Add qgroup assign test

[Qu Wenruo <wqu@suse.com>]

On 2020/9/20 下午4:57, Sidong Yang wrote:
> The btrfs/022 test is basic test about qgroup. but it doesn't have
> test with qgroup assign function. This patch adds parent assign
> test. parent assign test make two subvolumes and a qgroup for assign.
> Assign two subvolumes with a qgroup and check that quota of group
> has same value with sum of two subvolumes.

A little surprised that I haven't submitted such test case, especially
we had a fix in kernel.

cbab8ade585a ("btrfs: qgroup: mark qgroup inconsistent if we're
inherting snapshot to a new qgroup")

Despite the comment from Eryu, some btrfs specific comment inlined below.

> 
> Signed-off-by: Sidong Yang <realwakka@gmail.com>
> ---
>  tests/btrfs/022 | 40 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
> 
> diff --git a/tests/btrfs/022 b/tests/btrfs/022
> index aaa27aaa..cafaa8b2 100755
> --- a/tests/btrfs/022
> +++ b/tests/btrfs/022
> @@ -110,6 +110,40 @@ _limit_test_noexceed()
>  	[ $? -eq 0 ] || _fail "should have been allowed to write"
>  }
>  
> +#basic assign testing
> +_parent_assign_test()
> +{
> +	echo "=== parent assign test ===" >> $seqres.full
> +	_run_btrfs_util_prog subvolume create $SCRATCH_MNT/a
> +	_run_btrfs_util_prog quota enable $SCRATCH_MNT
> +	subvolid_a=$(_btrfs_get_subvolid $SCRATCH_MNT a)
> +
> +	_run_btrfs_util_prog subvolume create $SCRATCH_MNT/b
> +	_run_btrfs_util_prog quota enable $SCRATCH_MNT
> +	subvolid_b=$(_btrfs_get_subvolid $SCRATCH_MNT b)
> +
> +	_run_btrfs_util_prog qgroup create 1/100 $SCRATCH_MNT
> +
> +	_run_btrfs_util_prog qgroup assign 0/$subvolid_a 1/100 $SCRATCH_MNT
> +	_run_btrfs_util_prog qgroup assign 0/$subvolid_b 1/100 $SCRATCH_MNT

The coverage is not good enough.

Qgroup assign (or inherit) happens not only during "btrfs qgroup assign"
but also "btrfs subvolume snapshot -i".

And we also need to consider cases like shared extents between two
subvolumes (either caused by snapshot or reflink).

That means we have two factors, assign or snapshot -i, subvolumes with
shared extents or not.
That means we need at least 3 combinations:

- assign, no shared extents
- assign, shared extents
- snapshot -i, shared extents

(snapshot -i, no shared extents is invalid, as snapshot will always
cause shared extents)

> +
> +	_ddt of=$SCRATCH_MNT/a/file bs=4M count=1 >> $seqres.full 2>&1
> +	_ddt of=$SCRATCH_MNT/b/file bs=4M count=1 >> $seqres.full 2>&1
> +	sync
> +
> +	a_shared=$($BTRFS_UTIL_PROG qgroup show $units $SCRATCH_MNT | grep "0/$subvolid_a")
> +	a_shared=$(echo $a_shared | awk '{ print $2 }' | tr -dc '0-9')
> +
> +	b_shared=$($BTRFS_UTIL_PROG qgroup show $units $SCRATCH_MNT | grep "0/$subvolid_b")
> +	b_shared=$(echo $b_shared | awk '{ print $2 }' | tr -dc '0-9')
> +	sum=$(expr $b_shared  + $a_shared)
> +
> +	q_shared=$($BTRFS_UTIL_PROG qgroup show $units $SCRATCH_MNT | grep "1/100")
> +	q_shared=$(echo $q_shared | awk '{ print $2 }' | tr -dc '0-9')
> +
> +	[ $sum -eq $q_shared ] || _fail "shared values don't match"

Nope, we don't need to do such complex checking all by ourselves.

Just let "btrfs check" to handle it, as it will also check the qgroup
numbers.

Thanks,
Qu

> +}
> +
>  units=`_btrfs_qgroup_units`
>  
>  _scratch_mkfs > /dev/null 2>&1
> @@ -133,6 +167,12 @@ _check_scratch_fs
>  _scratch_mkfs > /dev/null 2>&1
>  _scratch_mount
>  _limit_test_noexceed
> +_scratch_unmount
> +_check_scratch_fs
> +
> +_scratch_mkfs > /dev/null 2>&1
> +_scratch_mount
> +_parent_assign_test
>  
>  # success, all done
>  echo "Silence is golden"
>