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[Qemu-devel] [PATCH v3 4/4] dataplane: refuse to start if device is alre
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH v3 4/4] dataplane: refuse to start if device is already in use |
Date: |
Mon, 29 Jul 2013 15:02:00 +0200 |
Dataplane must check whether a block device is in use before launching
the dataplane thread. This is necessary since the thread does not
synchronize with the main loop and I/O requests could cause corruption.
One example is when a drive is added and a block job is started before
hotplugging the virtio-blk-pci adapter. In this case we must not use
dataplane mode.
Cc: address@hidden
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
hw/block/dataplane/virtio-blk.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index 63c3ffa..411becc 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -415,6 +415,14 @@ bool virtio_blk_data_plane_create(VirtIODevice *vdev,
VirtIOBlkConf *blk,
return false;
}
+ /* If dataplane is (re-)enabled while the guest is running there could be
+ * block jobs that can conflict.
+ */
+ if (bdrv_in_use(blk->conf.bs)) {
+ error_report("cannot start dataplane thread while device is in use");
+ return false;
+ }
+
fd = raw_get_aio_fd(blk->conf.bs);
if (fd < 0) {
error_report("drive is incompatible with x-data-plane, "
--
1.8.1.4
- [Qemu-devel] [PATCH v3 0/4] dataplane: virtio-blk live migration with x-data-plane=on, Stefan Hajnoczi, 2013/07/29
- [Qemu-devel] [PATCH v3 1/4] migration: notify migration state before starting thread, Stefan Hajnoczi, 2013/07/29
- [Qemu-devel] [PATCH v3 2/4] migration: fix spice migration, Stefan Hajnoczi, 2013/07/29
- [Qemu-devel] [PATCH v3 3/4] dataplane: enable virtio-blk x-data-plane=on live migration, Stefan Hajnoczi, 2013/07/29
- [Qemu-devel] [PATCH v3 4/4] dataplane: refuse to start if device is already in use,
Stefan Hajnoczi <=
- Re: [Qemu-devel] [PATCH v3 0/4] dataplane: virtio-blk live migration with x-data-plane=on, Kevin Wolf, 2013/07/29
- Re: [Qemu-devel] [PATCH v3 0/4] dataplane: virtio-blk live migration with x-data-plane=on, Stefan Hajnoczi, 2013/07/29