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From: Andreas Dilger <adilger@dilger.ca>
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Subject: Re: [PATCH] tests: make m_assume_storage_prezeroed more robust
Date: Mon, 1 Apr 2024 16:20:35 -0600
In-Reply-To: <20231123030350.7418-1-adilger@dilger.ca>
Cc: Ext4 Developers List <linux-ext4@vger.kernel.org>
To: Theodore Ts'o <tytso@mit.edu>
References: <20231123030350.7418-1-adilger@dilger.ca>


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On Nov 22, 2023, at 8:03 PM, Andreas Dilger <adilger@dilger.ca> wrote:
>=20
> Don't assume that mke2fs is going to zero out an exact number
> of blocks when run with/without "-E assume_storage_prezeroed",
> since this depends on a number of different options that are
> not specified in the test script.

Another patch that looks like it fell between the cracks.  This
helps the m_assume_storage_prezeroed test pass consistently on
different systems.

Cheers, Andreas

> Instead, check that the number of blocks zeroed in the image is
> a small fraction (1/40th) of the number of blocks zeroed when
> "-E assume_sotrage_prezeroed" is not given, which makes it more
> robust when running in different environments.  This varies from
> 1/47 in the original test to 1/91 in my local test environment.
>=20
> Avoid "losetup --sector-size 4096", use "mke2fs -b 4096" instead.
> Clean up the loop device before checking "stat" so that all
> blocks are flushed to the backing storage before calling sync.
> Only one loop device and test file is needed for the test.
>=20
> Signed-off-by: Andreas Dilger <adilger@dilger.ca>
> ---
> tests/m_assume_storage_prezeroed/expect |  2 -
> tests/m_assume_storage_prezeroed/script | 64 ++++++++++++-------------
> 2 files changed, 30 insertions(+), 36 deletions(-)
> delete mode 100644 tests/m_assume_storage_prezeroed/expect
>=20
> diff --git a/tests/m_assume_storage_prezeroed/expect =
b/tests/m_assume_storage_prezeroed/expect
> deleted file mode 100644
> index b735e2425..000000000
> --- a/tests/m_assume_storage_prezeroed/expect
> +++ /dev/null
> @@ -1,2 +0,0 @@
> -> 10000
> -224
> diff --git a/tests/m_assume_storage_prezeroed/script =
b/tests/m_assume_storage_prezeroed/script
> index 1a8d84635..eea881428 100644
> --- a/tests/m_assume_storage_prezeroed/script
> +++ b/tests/m_assume_storage_prezeroed/script
> @@ -10,48 +10,44 @@ if test "$(id -u)" -ne 0 ; then
> elif ! command -v losetup >/dev/null ; then
>     echo "$test_name: $test_description: skipped (no losetup)"
> else
> -    dd if=3D/dev/zero of=3D$TMPFILE.1 bs=3D1 count=3D0 =
seek=3D$FILE_SIZE >> $LOG 2>&1
> -    dd if=3D/dev/zero of=3D$TMPFILE.2 bs=3D1 count=3D0 =
seek=3D$FILE_SIZE >> $LOG 2>&1
> +    dd if=3D/dev/zero of=3D$TMPFILE bs=3D1 count=3D0 seek=3D$FILE_SIZE =
>> $LOG 2>&1
>=20
> -    LOOP1=3D$(losetup --show --sector-size 4096 -f $TMPFILE.1)
> -    if [ ! -b "$LOOP1" ]; then
> -        echo "$test_name: $DESCRIPTION: skipped (no loop devices)"
> -        rm -f $TMPFILE.1 $TMPFILE.2
> -        exit 0
> -    fi
> -    LOOP2=3D$(losetup --show --sector-size 4096 -f $TMPFILE.2)
> -    if [ ! -b "$LOOP2" ]; then
> -        echo "$test_name: $DESCRIPTION: skipped (no loop devices)"
> -        rm -f $TMPFILE.1 $TMPFILE.2
> -	losetup -d $LOOP1
> -        exit 0
> +    LOOP=3D$(losetup --show -f $TMPFILE)
> +    if [ ! -b "$LOOP" ]; then
> +         echo "$test_name: $DESCRIPTION: skipped (no loop devices)"
> +         rm -f $TMPFILE
> +         exit 0
>     fi
>=20
> -    echo $MKE2FS -o Linux -t ext4 $LOOP1 >> $LOG 2>&1
> -    $MKE2FS -o Linux -t ext4 $LOOP1 >> $LOG 2>&1
> +    cmd=3D"$MKE2FS -o Linux -t ext4 -b 4096"
> +    echo "$cmd $LOOP" >> $LOG
> +    $cmd $LOOP >> $LOG 2>&1
> +    losetup -d $LOOP
>     sync
> -    stat $TMPFILE.1 >> $LOG 2>&1
> -    SZ=3D$(stat -c "%b" $TMPFILE.1)
> -    if test $SZ -gt 10000 ; then
> -	echo "> 10000" > $OUT
> -    else
> -	echo "$SZ" > $OUT
> +    stat $TMPFILE >> $LOG 2>&1
> +    BLOCKS_DEF=3D$(stat -c "%b" $TMPFILE)
> +
> +    > $TMPFILE
> +    dd if=3D/dev/zero of=3D$TMPFILE bs=3D1 count=3D0 seek=3D$FILE_SIZE =
>> $LOG 2>&1
> +    LOOP=3D$(losetup --show -f $TMPFILE)
> +    if [ ! -b "$LOOP" ]; then
> +         echo "$test_name: $DESCRIPTION: skipped (no loop devices)"
> +         rm -f $TMPFILE
> +         exit 0
>     fi
>=20
> -    echo $MKE2FS -o Linux -t ext4 -E assume_storage_prezeroed=3D1 =
$LOOP2 >> $LOG 2>&1
> -    $MKE2FS -o Linux -t ext4 -E assume_storage_prezeroed=3D1 $LOOP2 =
>> $LOG 2>&1
> +    cmd+=3D" -E assume_storage_prezeroed=3D1"
> +    echo "$cmd $LOOP" >> $LOG
> +    $cmd $TMPFILE >> $LOG 2>&1
> +    losetup -d $LOOP
>     sync
> -    stat $TMPFILE.2 >> $LOG 2>&1
> -    stat -c "%b" $TMPFILE.2 >> $OUT
> -
> -    losetup -d $LOOP1
> -    losetup -d $LOOP2
> -    rm -f $TMPFILE.1 $TMPFILE.2
> +    stat $TMPFILE >> $LOG 2>&1
> +    BLOCKS_ASP=3D$(stat -c "%b" $TMPFILE)
>=20
> -    cmp -s $OUT $EXP
> -    status=3D$?
> +    echo "blocks_dev: $BLOCKS_DEF blocks_asp: ${BLOCKS_ASP}" >> $LOG
>=20
> -    if [ "$status" =3D 0 ] ; then
> +    # should use less than 1/20 of the blocks with =
assume_storage_prezeroed
> +    if (( $BLOCKS_DEF > $BLOCKS_ASP * 40 )) ; then
> 	echo "$test_name: $test_description: ok"
> 	touch $test_name.ok
>     else
> @@ -60,4 +56,4 @@ else
> 	diff $EXP $OUT >> $test_name.failed
>     fi
> fi
> -unset LOG OUT EXP FILE_SIZE LOOP1 LOOP2
> +unset LOG OUT EXP FILE_SIZE LOOP


Cheers, Andreas


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