Re: [PATCH] fstests: generic/352 should accomodate other pwrite behaviors

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

On Wed, Aug 23, 2023 at 10:43:50AM -0500, Bill O'Donnell wrote:
> xfs_io pwrite issues a series of block size writes, but there is no guarantee
> that the resulting extent(s) will be singular or contiguous. This behavior is
> acceptable, but the test is flawed in that it expects a single extent for a
> pwrite.
> 
> Modify test to accept any layout for the reflinked logical range.
> 
> Signed-off-by: Bill O'Donnell <bodonnel@redhat.com>
> ---
>  tests/generic/352     | 16 +++++++++++-----
>  tests/generic/352.out |  2 --
>  2 files changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/tests/generic/352 b/tests/generic/352
> index 52ec4850..c4ee8a44 100755
> --- a/tests/generic/352
> +++ b/tests/generic/352
> @@ -48,19 +48,25 @@ _pwrite_byte 0xcdcdcdcd 0 $blocksize $file | _filter_xfs_io
>  # use reflink to create the rest of the file, whose all extents are all
>  # pointing to the first extent
>  for i in $(seq 1 $nr); do
> -	_reflink_range $file 0 $file $(($i * $blocksize)) $blocksize > /dev/null
> +	_reflink_range $file 0 $file $(($i * $blocksize)) $blocksize > $tmp1.out

$tmp1 isnt defined anywhere.

>  done
>  
>  # then call fiemap on that file to test both the shared flag and if
>  # reserved extent mapping search will cause soft lockup
> -$XFS_IO_PROG -c "fiemap -v" $file | _filter_fiemap_flags > $tmp.out
> -cat $tmp.out >> $seqres.full
> +$XFS_IO_PROG -c "fiemap -v" $file | _filter_fiemap_flags > $tmp2.out
> +cat $tmp2.out >> $seqres.full

Nor is $tmp2

>  
>  # refact the $LOAD_FACTOR to 1 to match the golden output
>  sed -i -e "s/$(($last_extent - 1))/$(($orig_last_extent - 1))/" \
>  	-e "s/$last_extent/$orig_last_extent/" \
> -	-e "s/$end/$orig_end/" $tmp.out
> -cat $tmp.out
> +	-e "s/$end/$orig_end/" $tmp2.out
> +
> +cat $tmp1.out > tmp.1
> +cat $tmp2.out > tmp.2

Not sure why you didn't make the _reflink_range and the fiemap above
output to $tmp.out1 and $tmp.out2, respectively.  If you had, then the
default _cleanup would delete $tmp.* automatically...

> +
> +diff tmp.[12]
> +rm tmp.1
> +rm tmp.2

...and the rm here wouldn't be necessary.

Ok.  Nitpicking over.  Moving on to the weirder design questions of the
original test:

[add original test author to cc]

I don't know why $blocksize is set to 128k above.  If this test needs to
guarantee that there would only be *one* extent (and the golden output
implies this as you note), then it should have been written to say:

	blocksize=$(_get_file_block_size $SCRATCH_MNT)

But I don't know if the "btrfs soft lock up and return wrong shared
flag" behavior required sharing a (probably multi-block) 128k range, or
if that was simply what the author selected because it reproduced the
problem.

>  
>  # success, all done
>  status=0
> diff --git a/tests/generic/352.out b/tests/generic/352.out
> index 4ff66c21..ad90ae0d 100644
> --- a/tests/generic/352.out
> +++ b/tests/generic/352.out
> @@ -1,5 +1,3 @@
>  QA output created by 352
>  wrote 131072/131072 bytes at offset 0
>  XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> -0: [0..2097151]: shared
> -1: [2097152..2097407]: shared|last

Also I suspect from the test description that the goal here was to
detect the golden output failing because the shared flag does not get
reported correctly.

--D
> -- 
> 2.41.0
>