Re: [PATCH 1/4] xfs/270: Fix ro mount failure when nrext64 option is enabled

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Jun 06, 2022 at 06:10:58PM +0530, Chandan Babu R wrote:
> With nrext64 option enabled at run time, the read-only mount performed by the
> test fails because,
> 1. mkfs.xfs would have calculated log size based on reflink being enabled.
> 2. Clearing the reflink ro compat bit causes log size calculations to yield a
>    different value.
> 3. In the case where nrext64 is enabled, this causes attr reservation to be
>    the largest among all the transaction reservations.
> 4. This ends up causing XFS to require a larger ondisk log size than that
>    which is available.
> 
> This commit fixes the problem by setting features_ro_compat to the value
> obtained by the bitwise-OR of features_ro_compat field with 2^31.
> 
> Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>
> ---
>  tests/xfs/270     | 16 ++++++++++++++--
>  tests/xfs/270.out |  1 -
>  2 files changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/tests/xfs/270 b/tests/xfs/270
> index 0ab0c7d8..f3796691 100755
> --- a/tests/xfs/270
> +++ b/tests/xfs/270
> @@ -27,8 +27,20 @@ _scratch_mkfs_xfs >>$seqres.full 2>&1
>  # set the highest bit of features_ro_compat, use it as an unknown
>  # feature bit. If one day this bit become known feature, please
>  # change this case.
> -_scratch_xfs_set_metadata_field "features_ro_compat" "$((2**31))" "sb 0" | \
> -	grep 'features_ro_compat'
> +ro_compat=$(_scratch_xfs_get_metadata_field "features_ro_compat" "sb 0")
> +ro_compat=${ro_compat##0x}
> +ro_compat="16#"${ro_compat}
> +ro_compat=$(($ro_compat|16#80000000))

I guess I just learned a  ^^^^^ new bashism today.

> +ro_compat=$(_scratch_xfs_set_metadata_field "features_ro_compat" "$ro_compat" \
> +					    "sb 0" | grep 'features_ro_compat')
> +
> +ro_compat=${ro_compat##features_ro_compat = 0x}
> +ro_compat="16#"${ro_compat}
> +ro_compat=$(($ro_compat&16#80000000))
> +if (( $ro_compat != 16#80000000 )); then
> +	echo "Unable to set most significant bit of features_ro_compat"
> +fi

Thanks for the fix,
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> +
>  
>  # rw mount with unknown ro-compat feature should fail
>  echo "rw mount test"
> diff --git a/tests/xfs/270.out b/tests/xfs/270.out
> index 0a8b3851..edf4c254 100644
> --- a/tests/xfs/270.out
> +++ b/tests/xfs/270.out
> @@ -1,5 +1,4 @@
>  QA output created by 270
> -features_ro_compat = 0x80000000
>  rw mount test
>  ro mount test
>  rw remount test
> -- 
> 2.35.1
>