From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45159) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XygAV-0007ZU-QW for qemu-devel@nongnu.org; Wed, 10 Dec 2014 07:15:05 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XygAO-0006Mt-Jk for qemu-devel@nongnu.org; Wed, 10 Dec 2014 07:14:59 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60849) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XygAO-0006Mg-CB for qemu-devel@nongnu.org; Wed, 10 Dec 2014 07:14:52 -0500 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id sBACEQGr032430 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Wed, 10 Dec 2014 07:14:51 -0500 From: Kevin Wolf Date: Wed, 10 Dec 2014 11:33:38 +0100 Message-Id: <1418207679-32260-13-git-send-email-kwolf@redhat.com> In-Reply-To: <1418207679-32260-1-git-send-email-kwolf@redhat.com> References: <1418207679-32260-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PULL 12/73] blockdev: acquire AioContext in change-backing-file List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com From: Stefan Hajnoczi Add dataplane support to the change-backing-file QMP commands. By acquiring the AioContext we avoid race conditions with the dataplane thread which may also be accessing the BlockDriverState. Note that this command operates on both bs and a node in its chain (image_bs). The bdrv_chain_contains(bs, image_bs) check guarantees that bs and image_bs are in the same AioContext. Signed-off-by: Stefan Hajnoczi Reviewed-by: Max Reitz Signed-off-by: Max Reitz Signed-off-by: Kevin Wolf --- blockdev.c | 19 +++++++++++++------ hw/block/dataplane/virtio-blk.c | 1 + 2 files changed, 14 insertions(+), 6 deletions(-) diff --git a/blockdev.c b/blockdev.c index 7bf88d4..a52f205 100644 --- a/blockdev.c +++ b/blockdev.c @@ -2584,6 +2584,7 @@ void qmp_change_backing_file(const char *device, Error **errp) { BlockDriverState *bs = NULL; + AioContext *aio_context; BlockDriverState *image_bs = NULL; Error *local_err = NULL; bool ro; @@ -2597,34 +2598,37 @@ void qmp_change_backing_file(const char *device, return; } + aio_context = bdrv_get_aio_context(bs); + aio_context_acquire(aio_context); + image_bs = bdrv_lookup_bs(NULL, image_node_name, &local_err); if (local_err) { error_propagate(errp, local_err); - return; + goto out; } if (!image_bs) { error_setg(errp, "image file not found"); - return; + goto out; } if (bdrv_find_base(image_bs) == image_bs) { error_setg(errp, "not allowing backing file change on an image " "without a backing file"); - return; + goto out; } /* even though we are not necessarily operating on bs, we need it to * determine if block ops are currently prohibited on the chain */ if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_CHANGE, errp)) { - return; + goto out; } /* final sanity check */ if (!bdrv_chain_contains(bs, image_bs)) { error_setg(errp, "'%s' and image file are not in the same chain", device); - return; + goto out; } /* if not r/w, reopen to make r/w */ @@ -2635,7 +2639,7 @@ void qmp_change_backing_file(const char *device, bdrv_reopen(image_bs, open_flags | BDRV_O_RDWR, &local_err); if (local_err) { error_propagate(errp, local_err); - return; + goto out; } } @@ -2655,6 +2659,9 @@ void qmp_change_backing_file(const char *device, error_propagate(errp, local_err); /* will preserve prior errp */ } } + +out: + aio_context_release(aio_context); } void qmp_blockdev_add(BlockdevOptions *options, Error **errp) diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index 2548113..90ab27e 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -197,6 +197,7 @@ void virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf, blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_RESIZE, s->blocker); blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_DRIVE_DEL, s->blocker); blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_BACKUP_SOURCE, s->blocker); + blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_CHANGE, s->blocker); blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_COMMIT, s->blocker); blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_EJECT, s->blocker); blk_op_unblock(conf->conf.blk, BLOCK_OP_TYPE_INTERNAL_SNAPSHOT_DELETE, -- 1.8.3.1