From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47560) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZbkzO-00038d-CG for qemu-devel@nongnu.org; Tue, 15 Sep 2015 03:49:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZbkzN-0003IU-1X for qemu-devel@nongnu.org; Tue, 15 Sep 2015 03:49:18 -0400 From: Markus Armbruster References: <1441878905-5272-1-git-send-email-wency@cn.fujitsu.com> <1441878905-5272-5-git-send-email-wency@cn.fujitsu.com> <87mvwpkqzi.fsf@blackfin.pond.sub.org> <55F7850A.5050109@cn.fujitsu.com> Date: Tue, 15 Sep 2015 09:49:07 +0200 In-Reply-To: <55F7850A.5050109@cn.fujitsu.com> (Wen Congyang's message of "Tue, 15 Sep 2015 10:40:10 +0800") Message-ID: <87613c86mk.fsf@blackfin.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH v3 4/5] qmp: add monitor command to add/remove a child List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wen Congyang Cc: Kevin Wolf , Alberto Garcia , zhanghailiang , qemu block , Jiang Yunhong , Dong Eddie , qemu devel , "Dr. David Alan Gilbert" , Gonglei , Stefan Hajnoczi , Yang Hongyang Wen Congyang writes: > On 09/14/2015 10:36 PM, Markus Armbruster wrote: >> Wen Congyang writes: >> >>> Signed-off-by: Wen Congyang >>> Signed-off-by: zhanghailiang >>> Signed-off-by: Gonglei >>> --- >>> blockdev.c | 47 ++++++++++++++++++++++++++++++++++++++++++++++ >>> qapi/block-core.json | 34 +++++++++++++++++++++++++++++++++ >>> qmp-commands.hx | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++++ >>> 3 files changed, 134 insertions(+) >>> >>> diff --git a/blockdev.c b/blockdev.c >>> index bd47756..0a40607 100644 >>> --- a/blockdev.c >>> +++ b/blockdev.c >>> @@ -3413,6 +3413,53 @@ fail: >>> qmp_output_visitor_cleanup(ov); >>> } >>> >>> +void qmp_x_child_add(const char *parent, const char *child, >>> + Error **errp) >>> +{ >>> + BlockDriverState *parent_bs, *child_bs; >>> + Error *local_err = NULL; >>> + >>> + parent_bs = bdrv_lookup_bs(parent, parent, &local_err); >>> + if (!parent_bs) { >>> + error_propagate(errp, local_err); >>> + return; >>> + } >>> + >>> + child_bs = bdrv_find_node(child); >>> + if (!child_bs) { >>> + error_setg(errp, "Node '%s' not found", child); >>> + return; >>> + } >>> + >>> + bdrv_add_child(parent_bs, child_bs, &local_err); >>> + if (local_err) { >>> + error_propagate(errp, local_err); >>> + } >>> +} >>> + >>> +void qmp_child_del(const char *parent, const char *child, Error **errp) >>> +{ >>> + BlockDriverState *parent_bs, *child_bs; >>> + Error *local_err = NULL; >>> + >>> + parent_bs = bdrv_lookup_bs(parent, parent, &local_err); >>> + if (!parent_bs) { >>> + error_propagate(errp, local_err); >>> + return; >>> + } >>> + >>> + child_bs = bdrv_find_node(child); >>> + if (!child_bs) { >>> + error_setg(errp, "Node '%s' not found", child); >>> + return; >>> + } >>> + >>> + bdrv_del_child(parent_bs, child_bs, &local_err); >>> + if (local_err) { >>> + error_propagate(errp, local_err); >>> + } >>> +} >>> + >>> BlockJobInfoList *qmp_query_block_jobs(Error **errp) >>> { >>> BlockJobInfoList *head = NULL, **p_next = &head; >>> diff --git a/qapi/block-core.json b/qapi/block-core.json >>> index e68a59f..b959577 100644 >>> --- a/qapi/block-core.json >>> +++ b/qapi/block-core.json >>> @@ -2272,3 +2272,37 @@ >>> ## >>> { 'command': 'block-set-write-threshold', >>> 'data': { 'node-name': 'str', 'write-threshold': 'uint64' } } >>> + >>> +## >>> +# @x-child-add >>> +# >>> +# Add a new child to the parent BDS. Currently only the Quorum driver >>> +# implements this feature. This is useful to fix a broken quorum child. >>> +# >>> +# @parent: graph node name or id which the child will be added to. >>> +# >>> +# @child: graph node name that will be added. >>> +# >>> +# Note: this command is experimental, and not a stable API. >>> +# >>> +# Since: 2.5 >>> +## >>> +{ 'command': 'x-child-add', >>> + 'data' : { 'parent': 'str', 'child': 'str' } } >>> + >>> +## >>> +# @child-del >>> +# >>> +# Remove a child from the parent BDS. Currently only the Quorum driver >>> +# implements this feature. This is useful to fix a broken quorum child. >>> +# Note, you can't remove a child if it would bring the quorum below its >>> +# threshold. >>> +# >>> +# @parent: graph node name or id from which the child will removed. >>> +# >>> +# @child: graph node name that will be removed. >>> +# >>> +# Since: 2.5 >>> +## >>> +{ 'command': 'child-del', >>> + 'data' : { 'parent': 'str', 'child': 'str' } } >> >> Why is x-child-add experimental, but child-del isn't? Please explain >> both in the schema and in the commit message. > > No special reason. Should I put child-del in experimental namespace? I found the reason for x-child-add in your v2: child-add ------------ Add a child to a quorum node. This command is still a work in progress. It doesn't support all block drivers. Stay away from it unless you want it to help with its development. Eric suggested to rename it to x-child-add, and you did. Good. You also shortened the "work in progress" note to just "Note: this command is experimental, and not a stable API." I'd like to have a more verbose note explaining *why* the command is experimental, both here and in qmp-commands.hx. "It doesn't support all block drivers" is a reason. Are the any others? Is child-del similarly unfinished? If yes, make it x-child-del to save us from later grief. If no: is child-del is only useful together with x-child-add? Then make it x-child-del regardless. >>> diff --git a/qmp-commands.hx b/qmp-commands.hx >>> index 495670b..139a23b 100644 >>> --- a/qmp-commands.hx >>> +++ b/qmp-commands.hx >>> @@ -4053,6 +4053,59 @@ Example: >>> EQMP >>> >>> { >>> + .name = "x-child-add", >>> + .args_type = "parent:B,child:B", >>> + .mhandler.cmd_new = qmp_marshal_input_x_child_add, >>> + }, >>> + >>> +SQMP >>> +x-child-add >>> +------------ >>> + >>> +Add a child to a quorum node. >>> + >>> +Arguments: >>> + >>> +- "parent": the quorum's id or node name >>> +- "child": the child node-name which will be added >> >> Node name parameters are usually named node-name or, if there's more >> than one, FOO-node-name. Unless we want to abandon that convention, >> this should therefore be node-name and child-node-name, or parent-node >> name and child-node-name. > > parent can be top BDS, so it can be id. node-name is a very common name, > and I think child or child-node-name is better. Kevin pointed out we want to move to names without a -node-name suffix. >>> + >>> +Note: this command is experimental, and not a stable API. >>> + >>> +Example: >>> + >>> +-> { "execute": "x-child-add", >>> + "arguments": { "parent": "disk1", "child": "new_node" } } >>> +<- { "return": {} } >>> + >>> +EQMP >>> + >>> + { >>> + .name = "child-del", >> >> Documentation and schema have x-child-add, actual command is child-add. >> Oops. > > Here is child-del.... You're right. I got confused... >>> + .args_type = "parent:B,child:B", >>> + .mhandler.cmd_new = qmp_marshal_input_child_del, >>> + }, >>> + >>> +SQMP >>> +child-del >>> +------------ >>> + >>> +Delete a child from a quorum node. It can be used to remove a broken >>> +quorum child. >>> + >>> +Arguments: >>> + >>> +- "parent": the quorum's id or node name >>> +- "child": the child node-name which will be removed >> >> Same comment as on x-child-add's parameter names. >> >>> + >>> +Example: >>> + >>> +-> { "execute": "child-del", >>> + "arguments": { "parent": "disk1", "child": "new_node" } } >>> +<- { "return": {} } >>> + >>> +EQMP >>> + >>> + { >>> .name = "query-named-block-nodes", >>> .args_type = "", >>> .mhandler.cmd_new = qmp_marshal_input_query_named_block_nodes, >> . >>