From 0ee9b6146fd9b451c21f3428fb363d5e659693b7 Mon Sep 17 00:00:00 2001

From: Stefan Hajnoczi <stefanha@redhat.com>

Date: Fri, 22 Dec 2017 11:08:55 +0100

Subject: [PATCH 37/42] blockdev: add x-blockdev-set-iothread testing command

RH-Author: Stefan Hajnoczi <stefanha@redhat.com>

Message-id: <20171222110900.24813-16-stefanha@redhat.com>

Patchwork-id: 78494

O-Subject: [RHV7.5 qemu-kvm-rhev PATCH 15/20] blockdev: add x-blockdev-set-iothread testing command

Bugzilla: 1519721

RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

RH-Acked-by: Jeffrey Cody <jcody@redhat.com>

RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

Currently there is no easy way for iotests to ensure that a BDS is bound

to a particular IOThread.  Normally the virtio-blk device calls

blk_set_aio_context() when dataplane is enabled during guest driver

initialization.  This never happens in iotests since -machine

accel=qtest means there is no guest activity (including device driver

initialization).

This patch adds a QMP command to explicitly assign IOThreads in test

cases.  See qapi/block-core.json for a description of the command.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Reviewed-by: Kevin Wolf <kwolf@redhat.com>

Reviewed-by: Eric Blake <eblake@redhat.com>

Message-id: 20171206144550.22295-9-stefanha@redhat.com

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

(cherry picked from commit ca00bbb153d03c5338d8c8136812163f463f841e)

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 blockdev.c           | 41 +++++++++++++++++++++++++++++++++++++++++

 qapi/block-core.json | 36 ++++++++++++++++++++++++++++++++++++

 2 files changed, 77 insertions(+)

diff --git a/blockdev.c b/blockdev.c

index f118444..6cbe627 100644

--- a/blockdev.c

+++ b/blockdev.c

@@ -46,6 +46,7 @@

 #include "qapi/qobject-output-visitor.h"

 #include "qapi/util.h"

 #include "sysemu/sysemu.h"

+#include "sysemu/iothread.h"

 #include "block/block_int.h"

 #include "qmp-commands.h"

 #include "block/trace.h"

@@ -4190,6 +4191,46 @@ BlockJobInfoList *qmp_query_block_jobs(Error **errp)

     return head;

 }

+void qmp_x_blockdev_set_iothread(const char *node_name, StrOrNull *iothread,

+                                 Error **errp)

+{

+    AioContext *old_context;

+    AioContext *new_context;

+    BlockDriverState *bs;

+

+    bs = bdrv_find_node(node_name);

+    if (!bs) {

+        error_setg(errp, "Cannot find node %s", node_name);

+        return;

+    }

+

+    /* If we want to allow more extreme test scenarios this guard could be

+     * removed.  For now it protects against accidents. */

+    if (bdrv_has_blk(bs)) {

+        error_setg(errp, "Node %s is in use", node_name);

+        return;

+    }

+

+    if (iothread->type == QTYPE_QSTRING) {

+        IOThread *obj = iothread_by_id(iothread->u.s);

+        if (!obj) {

+            error_setg(errp, "Cannot find iothread %s", iothread->u.s);

+            return;

+        }

+

+        new_context = iothread_get_aio_context(obj);

+    } else {

+        new_context = qemu_get_aio_context();

+    }

+

+    old_context = bdrv_get_aio_context(bs);

+    aio_context_acquire(old_context);

+

+    bdrv_set_aio_context(bs, new_context);

+

+    aio_context_release(old_context);

+}

+

 QemuOptsList qemu_common_drive_opts = {

     .name = "drive",

     .head = QTAILQ_HEAD_INITIALIZER(qemu_common_drive_opts.head),

diff --git a/qapi/block-core.json b/qapi/block-core.json

index 15fc08f..d579c99 100644

--- a/qapi/block-core.json

+++ b/qapi/block-core.json

@@ -3882,3 +3882,39 @@

   'data' : { 'parent': 'str',

              '*child': 'str',

              '*node': 'str' } }

+

+##

+# @x-blockdev-set-iothread:

+#

+# Move @node and its children into the @iothread.  If @iothread is null then

+# move @node and its children into the main loop.

+#

+# The node must not be attached to a BlockBackend.

+#

+# @node-name: the name of the block driver node

+#

+# @iothread: the name of the IOThread object or null for the main loop

+#

+# Note: this command is experimental and intended for test cases that need

+# control over IOThreads only.

+#

+# Since: 2.12

+#

+# Example:

+#

+# 1. Move a node into an IOThread

+# -> { "execute": "x-blockdev-set-iothread",

+#      "arguments": { "node-name": "disk1",

+#                     "iothread": "iothread0" } }

+# <- { "return": {} }

+#

+# 2. Move a node into the main loop

+# -> { "execute": "x-blockdev-set-iothread",

+#      "arguments": { "node-name": "disk1",

+#                     "iothread": null } }

+# <- { "return": {} }

+#

+##

+{ 'command': 'x-blockdev-set-iothread',

+  'data' : { 'node-name': 'str',

+             'iothread': 'StrOrNull' } }

-- 

1.8.3.1