diff mbox series

[1/2] iotests: Make _filter_img_create more active

Message ID 20200616131756.1073438-2-mreitz@redhat.com (mailing list archive)
State New, archived
Headers show
Series iotests: Make _filter_img_create more active | expand

Commit Message

Max Reitz June 16, 2020, 1:17 p.m. UTC
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(-)

Comments

Maxim Levitsky June 17, 2020, 11:46 a.m. UTC | #1
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. 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.
Which test needs it?

> +
> +    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.

> +
> +    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?

> +        | 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?

> +        | 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.

> +
> +    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.

Best regards,
	Maxim Levitsky
Max Reitz June 17, 2020, 1:50 p.m. UTC | #2
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! :)
Maxim Levitsky June 17, 2020, 2:02 p.m. UTC | #3
On Wed, 2020-06-17 at 15:50 +0200, Max Reitz wrote:
> 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.

Ah. Do we need this though? 
Assuming yes, maybe we should create a new filter called something like _filter_drive_backup_mirror
or something like that that would filter qmp output, and pipe the 'Formatting' line
to _filter_img_create which then can have the qmp parsing part removed?

> 
> 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).

Fair enough. A follow up patch can always be made to fix this.

> 
> 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:)

In my past experience, any knowelege eventually turns out to be useful.

> 
> > > +
> > > +    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! :)


Best regards,
	Maxim Levitsky
Max Reitz June 17, 2020, 2:20 p.m. UTC | #4
On 17.06.20 16:02, Maxim Levitsky wrote:
> On Wed, 2020-06-17 at 15:50 +0200, Max Reitz wrote:
>> 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.
> 
> Ah. Do we need this though? 
> Assuming yes, maybe we should create a new filter called something like _filter_drive_backup_mirror
> or something like that that would filter qmp output, and pipe the 'Formatting' line
> to _filter_img_create which then can have the qmp parsing part removed?

Hm.  I don’t think it would be that much more simpler.  (Instead of just
putting it into this function.)  But perhaps cleaner.

One of the problems is that I don’t want to actually parse JSON here.
That leaves us with the problem of what to do with line breaks.  Both
QMP stuff and any Formatting line may contain line breaks (and there
actually are iotests that have line breaks in their Formatting line).

In this function, I opted to allow line breaks in Formatting lines, but
not in QMP.  If we had a separate function specifically for Formatting
stuff in QMP, I think it should probably work the other way around.

So what this other function would do is probably to just echo all lines
that don’t start with Formatting, and filter those Formatting line(s)
through _filter_img_create.  (I don’t think we need to support
multi-line Formatting lines in QMP output.)

I think that should work.  And it’s probably indeed cleaner than putting
both into a single function.  I’ll try my hands on it.

[...]

>>>> +        | 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).
> 
> Fair enough. A follow up patch can always be made to fix this.

Right.

>> 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:)
> 
> In my past experience, any knowelege eventually turns out to be useful.

In my experience, some knowledge can turn out harmful, because suddenly
you’re the expert on it. O:)

(I really don’t want to be the expert on bash.  Luckily, though, we have
Eric who fills that role quite nicely already.)
diff mbox series

Patch

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 =="
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
+
+    readarray -td '' formatting_line < \
+        <(echo "$to_filter" | sed -e 's/, fmt=/\x0/')
+
+    filename_part=${formatting_line[0]}
+    if [ -n "${formatting_line[1]}" ]; then
+        options="fmt=${formatting_line[1]}"
+    else
+        options=''
     fi
 
-    $SED "${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[@]}")
+
+    # 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' \
+        | 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/' \
+        | sort \
+        | $SED -e 's/^[0-9]-//' \
+        | tr '\n\0' ' \n' \
+        | $SED -e 's/^ *$//' -e 's/ *$//'
+    )
+
+    echo -n "$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()