vhost/scsi: Respond to control queue operations
The vhost-scsi driver currently does not handle any control queue operations. In particular, vhost_scsi_ctl_handle_kick, merely prints out a debug message but does nothing else. This can cause guest VMs to hang. As part of SCSI recovery from an error, e.g., an I/O timeout, the SCSI midlayer attempts to abort the failed operation. The SCSI virtio driver translates the abort to a SCSI TMF request that gets put on the control queue (virtscsi_abort -> virtscsi_tmf). The SCSI virtio driver then waits indefinitely for this request to be completed, but it never will because vhost-scsi never responds to that request. To avoid a hang, always respond to control queue operations; explicitly reject TMF requests, and return a no-op response to event requests. Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Bijan Mottahedeh
Michael S. Tsirkin
parent
4542d623c7
commit
0d02dbd68c
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@ -1050,9 +1050,199 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
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mutex_unlock(&vq->mutex);
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}
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static void
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vhost_scsi_send_tmf_resp(struct vhost_scsi *vs,
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struct vhost_virtqueue *vq,
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int head, unsigned int out)
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{
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struct virtio_scsi_ctrl_tmf_resp __user *resp;
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struct virtio_scsi_ctrl_tmf_resp rsp;
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int ret;
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pr_debug("%s\n", __func__);
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memset(&rsp, 0, sizeof(rsp));
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rsp.response = VIRTIO_SCSI_S_FUNCTION_REJECTED;
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resp = vq->iov[out].iov_base;
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ret = __copy_to_user(resp, &rsp, sizeof(rsp));
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if (!ret)
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vhost_add_used_and_signal(&vs->dev, vq, head, 0);
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else
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pr_err("Faulted on virtio_scsi_ctrl_tmf_resp\n");
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}
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static void
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vhost_scsi_send_an_resp(struct vhost_scsi *vs,
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struct vhost_virtqueue *vq,
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int head, unsigned int out)
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{
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struct virtio_scsi_ctrl_an_resp __user *resp;
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struct virtio_scsi_ctrl_an_resp rsp;
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int ret;
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pr_debug("%s\n", __func__);
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memset(&rsp, 0, sizeof(rsp)); /* event_actual = 0 */
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rsp.response = VIRTIO_SCSI_S_OK;
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resp = vq->iov[out].iov_base;
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ret = __copy_to_user(resp, &rsp, sizeof(rsp));
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if (!ret)
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vhost_add_used_and_signal(&vs->dev, vq, head, 0);
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else
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pr_err("Faulted on virtio_scsi_ctrl_an_resp\n");
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}
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static void
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vhost_scsi_ctl_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
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{
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union {
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__virtio32 type;
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struct virtio_scsi_ctrl_an_req an;
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struct virtio_scsi_ctrl_tmf_req tmf;
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} v_req;
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struct iov_iter out_iter;
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unsigned int out = 0, in = 0;
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int head;
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size_t req_size, rsp_size, typ_size;
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size_t out_size, in_size;
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u8 *lunp;
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void *req;
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mutex_lock(&vq->mutex);
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/*
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* We can handle the vq only after the endpoint is setup by calling the
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* VHOST_SCSI_SET_ENDPOINT ioctl.
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*/
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if (!vq->private_data)
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goto out;
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vhost_disable_notify(&vs->dev, vq);
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for (;;) {
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head = vhost_get_vq_desc(vq, vq->iov,
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ARRAY_SIZE(vq->iov), &out, &in,
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NULL, NULL);
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pr_debug("vhost_get_vq_desc: head: %d, out: %u in: %u\n",
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head, out, in);
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/* On error, stop handling until the next kick. */
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if (unlikely(head < 0))
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break;
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/* Nothing new? Wait for eventfd to tell us they refilled. */
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if (head == vq->num) {
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if (unlikely(vhost_enable_notify(&vs->dev, vq))) {
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vhost_disable_notify(&vs->dev, vq);
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continue;
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}
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break;
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}
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/*
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* Get the size of request and response buffers.
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*/
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out_size = iov_length(vq->iov, out);
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in_size = iov_length(&vq->iov[out], in);
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/*
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* Copy over the virtio-scsi request header, which for a
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* ANY_LAYOUT enabled guest may span multiple iovecs, or a
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* single iovec may contain both the header + outgoing
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* WRITE payloads.
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*
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* copy_from_iter() will advance out_iter, so that it will
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* point at the start of the outgoing WRITE payload, if
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* DMA_TO_DEVICE is set.
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*/
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iov_iter_init(&out_iter, WRITE, vq->iov, out, out_size);
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req = &v_req.type;
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typ_size = sizeof(v_req.type);
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if (unlikely(!copy_from_iter_full(req, typ_size, &out_iter))) {
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vq_err(vq, "Faulted on copy_from_iter tmf type\n");
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/*
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* The size of the response buffer varies based on
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* the request type and must be validated against it.
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* Since the request type is not known, don't send
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* a response.
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*/
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continue;
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}
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switch (v_req.type) {
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case VIRTIO_SCSI_T_TMF:
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req = &v_req.tmf;
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lunp = &v_req.tmf.lun[0];
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req_size = sizeof(struct virtio_scsi_ctrl_tmf_req);
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rsp_size = sizeof(struct virtio_scsi_ctrl_tmf_resp);
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break;
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case VIRTIO_SCSI_T_AN_QUERY:
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case VIRTIO_SCSI_T_AN_SUBSCRIBE:
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req = &v_req.an;
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lunp = &v_req.an.lun[0];
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req_size = sizeof(struct virtio_scsi_ctrl_an_req);
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rsp_size = sizeof(struct virtio_scsi_ctrl_an_resp);
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break;
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default:
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vq_err(vq, "Unknown control request %d", v_req.type);
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continue;
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}
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/*
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* Check for a sane response buffer so we can report early
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* errors back to the guest.
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*/
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if (unlikely(in_size < rsp_size)) {
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vq_err(vq,
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"Resp buf too small, need min %zu bytes got %zu",
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rsp_size, in_size);
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/*
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* Notifications are disabled at this point;
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* continue so they can be eventually enabled
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* when processing terminates.
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*/
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continue;
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}
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if (unlikely(out_size < req_size)) {
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vq_err(vq,
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"Req buf too small, need min %zu bytes got %zu",
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req_size, out_size);
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vhost_scsi_send_bad_target(vs, vq, head, out);
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continue;
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}
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req += typ_size;
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req_size -= typ_size;
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if (unlikely(!copy_from_iter_full(req, req_size, &out_iter))) {
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vq_err(vq, "Faulted on copy_from_iter\n");
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vhost_scsi_send_bad_target(vs, vq, head, out);
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continue;
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}
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/* virtio-scsi spec requires byte 0 of the lun to be 1 */
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if (unlikely(*lunp != 1)) {
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vq_err(vq, "Illegal virtio-scsi lun: %u\n", *lunp);
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vhost_scsi_send_bad_target(vs, vq, head, out);
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continue;
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}
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if (v_req.type == VIRTIO_SCSI_T_TMF) {
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pr_debug("%s tmf %d\n", __func__, v_req.tmf.subtype);
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vhost_scsi_send_tmf_resp(vs, vq, head, out);
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} else
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vhost_scsi_send_an_resp(vs, vq, head, out);
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}
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out:
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mutex_unlock(&vq->mutex);
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}
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static void vhost_scsi_ctl_handle_kick(struct vhost_work *work)
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{
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struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
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poll.work);
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struct vhost_scsi *vs = container_of(vq->dev, struct vhost_scsi, dev);
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pr_debug("%s: The handling func for control queue.\n", __func__);
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vhost_scsi_ctl_handle_vq(vs, vq);
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}
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static void
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