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Re: [Qemu-block] [Qemu-devel] [PATCH for-2.12 2/3] block: Handle null ba
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH for-2.12 2/3] block: Handle null backing link |
Date: |
Tue, 14 Nov 2017 16:17:18 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.3 (gnu/linux) |
Max Reitz <address@hidden> writes:
> Instead of converting all "backing": null instances into "backing": "",
> handle a null value directly in bdrv_open_inherit().
>
> This enables explicitly null backing links for json:{} filenames.
>
> Signed-off-by: Max Reitz <address@hidden>
> ---
> block.c | 2 +-
> blockdev.c | 14 --------------
> tests/qemu-iotests/089 | 20 ++++++++++++++++++++
> tests/qemu-iotests/089.out | 8 ++++++++
> 4 files changed, 29 insertions(+), 15 deletions(-)
>
> diff --git a/block.c b/block.c
> index 85427df577..bc92ddd5a0 100644
> --- a/block.c
> +++ b/block.c
> @@ -2558,7 +2558,7 @@ static BlockDriverState *bdrv_open_inherit(const char
> *filename,
>
> /* See cautionary note on accessing @options above */
> backing = qdict_get_try_str(options, "backing");
> - if (backing && *backing == '\0') {
> + if (qdict_is_qnull(options, "backing") || (backing && *backing == '\0'))
> {
> flags |= BDRV_O_NO_BACKING;
> qdict_del(options, "backing");
> }
Consider a comment pointing out "" is deprecated.
See also my reply to PATCH 1/3.
> diff --git a/blockdev.c b/blockdev.c
> index 56a6b24a0b..99ef618b39 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -3885,7 +3885,6 @@ void qmp_blockdev_add(BlockdevOptions *options, Error
> **errp)
> QObject *obj;
> Visitor *v = qobject_output_visitor_new(&obj);
> QDict *qdict;
> - const QDictEntry *ent;
> Error *local_err = NULL;
>
> visit_type_BlockdevOptions(v, NULL, &options, &local_err);
> @@ -3899,19 +3898,6 @@ void qmp_blockdev_add(BlockdevOptions *options, Error
> **errp)
>
> qdict_flatten(qdict);
>
> - /*
> - * Rewrite "backing": null to "backing": ""
> - * TODO Rewrite "" to null instead, and perhaps not even here
> - */
> - for (ent = qdict_first(qdict); ent; ent = qdict_next(qdict, ent)) {
> - char *dot = strrchr(ent->key, '.');
> -
> - if (!strcmp(dot ? dot + 1 : ent->key, "backing")
> - && qobject_type(ent->value) == QTYPE_QNULL) {
> - qdict_put(qdict, ent->key, qstring_new());
> - }
> - }
> -
> if (!qdict_get_try_str(qdict, "node-name")) {
> error_setg(errp, "'node-name' must be specified for the root node");
> goto fail;
> diff --git a/tests/qemu-iotests/089 b/tests/qemu-iotests/089
> index 9bfe2307b3..832eac1248 100755
> --- a/tests/qemu-iotests/089
> +++ b/tests/qemu-iotests/089
> @@ -82,6 +82,26 @@ $QEMU_IO_PROG --cache $CACHEMODE \
> $QEMU_IO -c 'read -P 42 0 512' "$TEST_IMG" | _filter_qemu_io
>
>
> +echo
> +echo "=== Testing correct handling of 'backing':null ==="
> +echo
> +
> +_make_test_img -b "$TEST_IMG.base" $IMG_SIZE
> +
> +# This should read 42
> +$QEMU_IO -c 'read -P 42 0 512' "$TEST_IMG" | _filter_qemu_io
> +
> +# This should read 0
> +$QEMU_IO -c 'read -P 0 0 512' "json:{\
> + 'driver': '$IMGFMT',
> + 'file': {
> + 'driver': 'file',
> + 'filename': '$TEST_IMG'
> + },
> + 'backing': null
> +}" | _filter_qemu_io
> +
> +
> # Taken from test 071
> echo
> echo "=== Testing blkdebug ==="
> diff --git a/tests/qemu-iotests/089.out b/tests/qemu-iotests/089.out
> index 18f5fdda7a..607a9c6d9c 100644
> --- a/tests/qemu-iotests/089.out
> +++ b/tests/qemu-iotests/089.out
> @@ -19,6 +19,14 @@ Pattern verification failed at offset 0, 512 bytes
> read 512/512 bytes at offset 0
> 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
>
> +=== Testing correct handling of 'backing':null ===
> +
> +Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
> backing_file=TEST_DIR/t.IMGFMT.base
> +read 512/512 bytes at offset 0
> +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> +read 512/512 bytes at offset 0
> +512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> +
> === Testing blkdebug ===
>
> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
Reviewed-by: Markus Armbruster <address@hidden>
- Re: [Qemu-block] [Qemu-devel] [PATCH for-2.12 1/3] qapi: Add qdict_is_null(), (continued)
[Qemu-block] [PATCH for-2.12 2/3] block: Handle null backing link, Max Reitz, 2017/11/10
[Qemu-block] [PATCH for-2.12 3/3] block: Deprecate "backing": "", Max Reitz, 2017/11/10