From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57493) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1g71r2-0002NB-US for qemu-devel@nongnu.org; Mon, 01 Oct 2018 13:19:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1g71qz-00075N-3L for qemu-devel@nongnu.org; Mon, 01 Oct 2018 13:19:31 -0400 From: Kevin Wolf Date: Mon, 1 Oct 2018 19:18:44 +0200 Message-Id: <20181001171901.11004-7-kwolf@redhat.com> In-Reply-To: <20181001171901.11004-1-kwolf@redhat.com> References: <20181001171901.11004-1-kwolf@redhat.com> Subject: [Qemu-devel] [PULL 06/23] block: Allow child references on reopen List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-block@nongnu.org Cc: kwolf@redhat.com, peter.maydell@linaro.org, qemu-devel@nongnu.org From: Alberto Garcia In the previous patches we removed all child references from bs->{options,explicit_options} because keeping them is useless and wrong. Because of this, any attempt to reopen a BlockDriverState using a child reference as one of its options would result in a failure, because bdrv_reopen_prepare() would detect that there's a new option (the child reference) that wasn't present in bs->options. But passing child references on reopen can be useful. It's a way to specify a BDS's child without having to pass recursively all of the child's options, and if the reference points to a different BDS then this can allow us to replace the child. However, replacing the child is something that needs to be implemented case by case and only when it makes sense. For now, this patch allows passing a child reference as long as it points to the current child of the BlockDriverState. It's also important to remember that, as a consequence of the previous patches, this child reference will be removed from bs->{options,explicit_options} after the reopening has been completed. Signed-off-by: Alberto Garcia Reviewed-by: Max Reitz Signed-off-by: Kevin Wolf --- block.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/block.c b/block.c index 98aca56785..ff1aded4b8 100644 --- a/block.c +++ b/block.c @@ -3242,6 +3242,24 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, QObject *new = entry->value; QObject *old = qdict_get(reopen_state->bs->options, entry->key); + /* Allow child references (child_name=node_name) as long as they + * point to the current child (i.e. everything stays the same). */ + if (qobject_type(new) == QTYPE_QSTRING) { + BdrvChild *child; + QLIST_FOREACH(child, &reopen_state->bs->children, next) { + if (!strcmp(child->name, entry->key)) { + break; + } + } + + if (child) { + const char *str = qobject_get_try_str(new); + if (!strcmp(child->bs->node_name, str)) { + continue; /* Found child with this name, skip option */ + } + } + } + /* * TODO: When using -drive to specify blockdev options, all values * will be strings; however, when using -blockdev, blockdev-add or -- 2.13.6