Re: [PATCH 1/2] iotests: Make _filter_img_create more active

[Max Reitz <mreitz@redhat.com>]

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On 17.06.20 13:46, Maxim Levitsky wrote:
> On Tue, 2020-06-16 at 15:17 +0200, Max Reitz wrote:
>> Right now, _filter_img_create just filters out everything that looks
>> format-dependent, and applies some filename filters.  That means that we
>> have to add another filter line every time some format gets a new
>> creation option.  This can be avoided by instead discarding everything
>> and just keeping what we know is format-independent (format, size,
>> backing file, encryption information[1], preallocation) or just
>> interesting to have in the reference output (external data file path).
>>
>> Furthermore, we probably want to sort these options.  Format drivers are
>> not required to define them in any specific order, so the output is
>> effectively random (although this has never bothered us until now).  We
>> need a specific order for our reference outputs, though.  Unfortunately,
>> just using a plain "sort" would change a lot of existing reference
>> outputs, so we have to pre-filter the option keys to keep our existing
>> order (fmt, size, backing*, data, encryption info, preallocation).
>>
>> [1] Actually, the only thing that is really important is whether
>>     encryption is enabled or not.  A patch by Maxim thus removes all
>>     other "encrypt.*" options from the output:
>>     https://lists.nongnu.org/archive/html/qemu-block/2020-06/msg00339.html
>>     But that patch needs to come later so we can get away with changing
>>     as few reference outputs in this patch here as possible.
>>
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>> ---
>>  tests/qemu-iotests/112.out       |   2 +-
>>  tests/qemu-iotests/153           |   9 ++-
>>  tests/qemu-iotests/common.filter | 100 +++++++++++++++++++++++--------
>>  3 files changed, 81 insertions(+), 30 deletions(-)
>>
>> diff --git a/tests/qemu-iotests/112.out b/tests/qemu-iotests/112.out
>> index ae0318cabe..182655dbf6 100644
>> --- a/tests/qemu-iotests/112.out
>> +++ b/tests/qemu-iotests/112.out
>> @@ -5,7 +5,7 @@ QA output created by 112
>>  qemu-img: TEST_DIR/t.IMGFMT: Refcount width must be a power of two and may not exceed 64 bits
>>  Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
>>  qemu-img: TEST_DIR/t.IMGFMT: Refcount width must be a power of two and may not exceed 64 bits
>> -Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 refcount_bits=-1
>> +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
>>  qemu-img: TEST_DIR/t.IMGFMT: Refcount width must be a power of two and may not exceed 64 bits
>>  Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
>>  qemu-img: TEST_DIR/t.IMGFMT: Refcount width must be a power of two and may not exceed 64 bits
>> diff --git a/tests/qemu-iotests/153 b/tests/qemu-iotests/153
>> index cf961d3609..11e3d28841 100755
>> --- a/tests/qemu-iotests/153
>> +++ b/tests/qemu-iotests/153
>> @@ -167,11 +167,10 @@ done
>>  
>>  echo
>>  echo "== Creating ${TEST_IMG}.[abc] ==" | _filter_testdir
>> -(
>> -    $QEMU_IMG create -f qcow2 "${TEST_IMG}.a" -b "${TEST_IMG}"
>> -    $QEMU_IMG create -f qcow2 "${TEST_IMG}.b" -b "${TEST_IMG}"
>> -    $QEMU_IMG create -f qcow2 "${TEST_IMG}.c" -b "${TEST_IMG}.b"
>> -) | _filter_img_create
>> +$QEMU_IMG create -f qcow2 "${TEST_IMG}.a" -b "${TEST_IMG}" | _filter_img_create
>> +$QEMU_IMG create -f qcow2 "${TEST_IMG}.b" -b "${TEST_IMG}" | _filter_img_create
>> +$QEMU_IMG create -f qcow2 "${TEST_IMG}.c" -b "${TEST_IMG}.b" \
>> +    | _filter_img_create
>>  
>>  echo
>>  echo "== Two devices sharing the same file in backing chain =="
> 
> I guess this is done because now the filter expectes only a single
> qemu-img output.

Yes, that’s right.

> IMHO this is better anyway.
> 
>> diff --git a/tests/qemu-iotests/common.filter b/tests/qemu-iotests/common.filter
>> index 03e4f71808..f104ad7a9b 100644
>> --- a/tests/qemu-iotests/common.filter
>> +++ b/tests/qemu-iotests/common.filter
>> @@ -122,38 +122,90 @@ _filter_actual_image_size()
>>  # replace driver-specific options in the "Formatting..." line
>>  _filter_img_create()
>>  {
>> -    data_file_filter=()
>> -    if data_file=$(_get_data_file "$TEST_IMG"); then
>> -        data_file_filter=(-e "s# data_file=$data_file##")
>> +    # Keep QMP output unchanged
>> +    qmp_pre=''
>> +    qmp_post=''
>> +    to_filter=''
>> +
>> +    while read -r line; do
>> +        if echo "$line" | grep -q '^{.*}$'; then
>> +            if [ -z "$to_filter" ]; then
>> +                # Use $'\n' so the newline is not dropped on variable
>> +                # expansion
>> +                qmp_pre="$qmp_pre$line"$'\n'
>> +            else
>> +                qmp_post="$qmp_post$line"$'\n'
>> +            fi
>> +        else
>> +            to_filter="$to_filter$line"$'\n'
>> +        fi
>> +    done
> 
> The above code basically assumes that qmp output starts with '{' and ends with '}'
> which I guess is fair, and then it assumes that we can have set of qmp commands prior
> to qemu-img line and another set of qmp commands after it.
> To me it feels like we should have another filter for that, since
> qemu-img itself doesn't use qmp.

Yes, but drive-backup and drive-mirror with mode=absolute-paths use
bdrv_img_create() (quiet=false), which emits the “Formatting” line, too.
 So some QMP commands may emit it and then require the same filtering as
qemu-img create.

Not having to do that would certainly make things simpler.

> Which test needs it?

141.

>> +
>> +    readarray -td '' formatting_line < \
>> +        <(echo "$to_filter" | sed -e 's/, fmt=/\x0/')
> OK, took me a while to understand what this does, but looks OK.

Maybe I should at least put a comment like “Split $to_filter into the
pre-options part (before ", fmt=") and the options part (starting with
"fmt=").

>> +
>> +    filename_part=${formatting_line[0]}
>> +    if [ -n "${formatting_line[1]}" ]; then
>> +        options="fmt=${formatting_line[1]}"
>> +    else
>> +        options=''
>>      fi
>>
> OK.
> 
>>  
>> -    $SED "${data_file_filter[@]}" \
>> +    # Set grep_data_file to '\|data_file' to keep it; make it empty
>> +    # to drop it.
>> +    # We want to drop it if it is part of the global $IMGOPTS, and we
>> +    # want to keep it otherwise (if the test specifically wants to
>> +    # test data files).
>> +    grep_data_file='\|data_file'
>> +    if _get_data_file "$TEST_IMG" > /dev/null; then
>> +        grep_data_file=''
>> +    fi
>> +
>> +    filename_filters=(
>>          -e "s#$REMOTE_TEST_DIR#TEST_DIR#g" \
>>          -e "s#$IMGPROTO:$TEST_DIR#TEST_DIR#g" \
>>          -e "s#$TEST_DIR#TEST_DIR#g" \
>>          -e "s#$SOCK_DIR#SOCK_DIR#g" \
>>          -e "s#$IMGFMT#IMGFMT#g" \
>>          -e 's#nbd:127.0.0.1:[0-9]\\+#TEST_DIR/t.IMGFMT#g' \
>> -        -e 's#nbd+unix:///\??socket=SOCK_DIR/nbd#TEST_DIR/t.IMGFMT#g' \
>> -        -e "s# encryption=off##g" \
>> -        -e "s# cluster_size=[0-9]\\+##g" \
>> -        -e "s# table_size=[0-9]\\+##g" \
>> -        -e "s# compat=[^ ]*##g" \
>> -        -e "s# compat6=\\(on\\|off\\)##g" \
>> -        -e "s# static=\\(on\\|off\\)##g" \
>> -        -e "s# zeroed_grain=\\(on\\|off\\)##g" \
>> -        -e "s# subformat=[^ ]*##g" \
>> -        -e "s# adapter_type=[^ ]*##g" \
>> -        -e "s# hwversion=[^ ]*##g" \
>> -        -e "s# lazy_refcounts=\\(on\\|off\\)##g" \
>> -        -e "s# block_size=[0-9]\\+##g" \
>> -        -e "s# block_state_zero=\\(on\\|off\\)##g" \
>> -        -e "s# log_size=[0-9]\\+##g" \
>> -        -e "s# refcount_bits=[0-9]\\+##g" \
>> -        -e "s# key-secret=[a-zA-Z0-9]\\+##g" \
>> -        -e "s# iter-time=[0-9]\\+##g" \
>> -        -e "s# force_size=\\(on\\|off\\)##g" \
>> -        -e "s# compression_type=[a-zA-Z0-9]\\+##g"
>> +        -e 's#nbd+unix:///\??socket=SOCK_DIR/nbd#TEST_DIR/t.IMGFMT#g'
>> +    )
>> +
>> +    filename_part=$(echo "$filename_part" | $SED "${filename_filters[@]}")
> Looks good as well.
> 
>> +
>> +    # Break the option line before each option (preserving pre-existing
>> +    # line breaks by replacing them by \0 and restoring them at the end),
>> +    # then filter out the options we want to keep and sort them according
>> +    # to some order that all block drivers used at the time of writing
>> +    # this function.
>> +    options=$(
>> +        echo "$options" \
>> +        | tr '\n' '\0' \
>> +        | sed -e 's/\x0$//' -e 's/ \([a-z0-9_.-]*\)=/\n\1=/g' \
> You sometimes use $SED and sometimes sed. Is this intentional?

Oops, no.  It should be $SED everywhere.

>> +        | grep -ae "^\(fmt\\|size\\|backing\\|preallocation\\|encrypt$grep_data_file\\)" \
>> +        | $SED "${filename_filters[@]}" \
>> +            -e 's/^\(fmt\)/0-\1/' \
>> +            -e 's/^\(size\)/1-\1/' \
>> +            -e 's/^\(backing\)/2-\1/' \
>> +            -e 's/^\(data_file\)/3-\1/' \
>> +            -e 's/^\(encryption\)/4-\1/' \
>> +            -e 's/^\(encrypt\.format\)/5-\1/' \
>> +            -e 's/^\(encrypt\.key-secret\)/6-\1/' \
>> +            -e 's/^\(encrypt\.iter-time\)/7-\1/' \
>> +            -e 's/^\(preallocation\)/8-\1/' \
> All right, I understand this now, but do we have to do this?
> Maybe it is better to just update the outputs once to avoid keeping
> the custom sort order?

Well.  I don’t know.  The advantage of doing this is that I can’t
accidentally miss updating any reference outputs that aren’t used on my
machine (like 026.out.nocache or 051.out).

So we don’t strictly have to do this, but I found this to be simpler.
If someone wants to drop this and in turn update all reference outputs,
they’ll be my guest, but I preferred not to do that myself.

>> +        | sort \
>> +        | $SED -e 's/^[0-9]-//' \
>> +        | tr '\n\0' ' \n' \
>> +        | $SED -e 's/^ *$//' -e 's/ *$//'
>> +    )
> 
> For the above bash pipeline overall: It was hard to decipher :-), but I must admit
> I learned something from it.

I definitely learned something while working on this, too.  I’m not sure
whether I also gained any useful knowledge, though. O:)

>> +
>> +    echo -n "$qmp_pre"
>> +    if [ -n "$options" ]; then
>> +        echo "$filename_part, $options"
>> +    elif [ -n "$filename_part" ]; then
>> +        echo "$filename_part"
>> +    fi
>> +    echo -n "$qmp_post"
>>  }
>>  
>>  _filter_img_create_size()
> 
> Overall I like the idea of this patch.

Good!

Thanks for reviewing! :)


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