Re: [Qemu-devel] [PATCH 06/10] scsi: prepare migration code for usb-storage support

[Paolo Bonzini]

Il 25/05/2012 11:44, Gerd Hoffmann ha scritto:
> usb-storage can't handle requests in one go as the data transfer can be
> splitted into lots of usb packets.  Because of that there can be
> normal in-flight requests at savevm time and we need to handle that.
> With other scsi hba's this happens only in case i/o is stopped due to
> errors and there are pending requests which need to be restarted
> (req->retry = true).
> 
> So, first we need to save req->retry and then handle the req->retry =
> false case.  Write requests are handled fine already.  For read requests
> we have to save the buffer as we will not restart the request (and thus
> not refill the buffer) on the target host.
> 
> Cc: Paolo Bonzini <address@hidden>
> Signed-off-by: Gerd Hoffmann <address@hidden>
> ---
>  hw/scsi-bus.c  |    8 ++++----
>  hw/scsi-disk.c |   13 +++++++++++--
>  2 files changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/scsi-bus.c b/hw/scsi-bus.c
> index 8ab9bcd..92b8176 100644
> --- a/hw/scsi-bus.c
> +++ b/hw/scsi-bus.c
> @@ -1507,10 +1507,9 @@ static void put_scsi_requests(QEMUFile *f, void *pv, 
> size_t size)
>      QTAILQ_FOREACH(req, &s->requests, next) {
>          assert(!req->io_canceled);
>          assert(req->status == -1);
> -        assert(req->retry);
>          assert(req->enqueued);
>  
> -        qemu_put_sbyte(f, 1);
> +        qemu_put_sbyte(f, req->retry ? 1 : 2);
>          qemu_put_buffer(f, req->cmd.buf, sizeof(req->cmd.buf));
>          qemu_put_be32s(f, &req->tag);
>          qemu_put_be32s(f, &req->lun);
> @@ -1528,8 +1527,9 @@ static int get_scsi_requests(QEMUFile *f, void *pv, 
> size_t size)
>  {
>      SCSIDevice *s = pv;
>      SCSIBus *bus = DO_UPCAST(SCSIBus, qbus, s->qdev.parent_bus);
> +    int8_t sbyte;
>  
> -    while (qemu_get_sbyte(f)) {
> +    while ((sbyte = qemu_get_sbyte(f)) > 0) {
>          uint8_t buf[SCSI_CMD_BUF_SIZE];
>          uint32_t tag;
>          uint32_t lun;
> @@ -1539,6 +1539,7 @@ static int get_scsi_requests(QEMUFile *f, void *pv, 
> size_t size)
>          qemu_get_be32s(f, &tag);
>          qemu_get_be32s(f, &lun);
>          req = scsi_req_new(s, tag, lun, buf, NULL);
> +        req->retry = (sbyte == 1);
>          if (bus->info->load_request) {
>              req->hba_private = bus->info->load_request(f, req);
>          }
> @@ -1547,7 +1548,6 @@ static int get_scsi_requests(QEMUFile *f, void *pv, 
> size_t size)
>          }
>  
>          /* Just restart it later.  */
> -        req->retry = true;
>          scsi_req_enqueue_internal(req);
>  
>          /* At this point, the request will be kept alive by the reference
> diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
> index 045c764..4fd39ff 100644
> --- a/hw/scsi-disk.c
> +++ b/hw/scsi-disk.c
> @@ -132,8 +132,13 @@ static void scsi_disk_save_request(QEMUFile *f, 
> SCSIRequest *req)
>      qemu_put_be64s(f, &r->sector);
>      qemu_put_be32s(f, &r->sector_count);
>      qemu_put_be32s(f, &r->buflen);
> -    if (r->buflen && r->req.cmd.mode == SCSI_XFER_TO_DEV) {
> -        qemu_put_buffer(f, r->iov.iov_base, r->iov.iov_len);
> +    if (r->buflen) {
> +        if (r->req.cmd.mode == SCSI_XFER_TO_DEV) {
> +            qemu_put_buffer(f, r->iov.iov_base, r->iov.iov_len);
> +        } else if (!req->retry) {
> +            qemu_put_be64s(f, &r->iov.iov_len);
> +            qemu_put_buffer(f, r->iov.iov_base, r->iov.iov_len);
> +        }
>      }
>  }
>  
> @@ -148,6 +153,10 @@ static void scsi_disk_load_request(QEMUFile *f, 
> SCSIRequest *req)
>          scsi_init_iovec(r, r->buflen);
>          if (r->req.cmd.mode == SCSI_XFER_TO_DEV) {
>              qemu_get_buffer(f, r->iov.iov_base, r->iov.iov_len);
> +        } else if (!r->req.retry) {
> +            qemu_get_be64s(f, &r->iov.iov_len);
> +            assert(r->iov.iov_len <= r->buflen);
> +            qemu_get_buffer(f, r->iov.iov_base, r->iov.iov_len);
>          }
>      }
>  

Acked-by: Paolo Bonzini <address@hidden>

Feel free to push this to Anthony yourself
.

Paolo