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dataplane: refuse to start if device is already in use

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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: qemu-stable@nongnu.org
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2013-07-29 15:02:00 +02:00
parent 84db52d059
commit b0f2027cde
1 changed files with 8 additions and 0 deletions
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8
hw/block/dataplane/virtio-blk.c
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@ -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, "