Commit ca00bbb1 authored by Stefan Hajnoczi's avatar Stefan Hajnoczi
Browse files

blockdev: add x-blockdev-set-iothread testing command 



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: default avatarStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Message-id: 20171206144550.22295-9-stefanha@redhat.com
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent fbcc6923

blockdev.c

+41 −0
Original line number Diff line number Diff line
@@ -45,6 +45,7 @@ 
#include "qapi/qmp/qerror.h"

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

#include "sysemu/sysemu.h"

#include "sysemu/iothread.h"

#include "block/block_int.h"

#include "qmp-commands.h"

#include "block/trace.h"
@@ -4129,6 +4130,46 @@ 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),

qapi/block-core.json

+36 −0
Original line number Diff line number Diff line
@@ -3949,3 +3949,39 @@ 
  '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' } }