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 <mre...@redhat.com> --- 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"); } 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 -- 2.13.6