Re: [Minios-devel] [UNIKRAFT PATCH v3 14/17] plat/xen/drivers/blk: Flush requests

[Costin Lupu <costin.lupu@xxxxxxxxx>]

Reviewed-by: Costin Lupu <costin.lupu@xxxxxxxxx>

On 10/30/19 5:54 PM, Roxana Nicolescu wrote:
> This patch introduces the flush requests.
> This operation garantees that all previous write requests are finished.
> 
> Signed-off-by: Roxana Nicolescu <nicolescu.roxana1996@xxxxxxxxx>
> ---
>  plat/xen/drivers/blk/blkfront.c    | 25 +++++++++++++++++++++++++
>  plat/xen/drivers/blk/blkfront.h    |  8 ++++++++
>  plat/xen/drivers/blk/blkfront_xs.c | 15 +++++++++++++++
>  3 files changed, 48 insertions(+)
> 
> diff --git a/plat/xen/drivers/blk/blkfront.c b/plat/xen/drivers/blk/blkfront.c
> index 2129f191..5866c8e7 100644
> --- a/plat/xen/drivers/blk/blkfront.c
> +++ b/plat/xen/drivers/blk/blkfront.c
> @@ -150,6 +150,29 @@ static int blkfront_request_write(struct 
> blkfront_request *blkfront_req,
>       return rc;
>  }
>  
> +static int blkfront_request_flush(struct blkfront_request *blkfront_req,
> +             struct blkif_request *ring_req)
> +{
> +     struct blkfront_dev *dev;
> +     struct uk_blkdev_queue *queue;
> +
> +     UK_ASSERT(ring_req);
> +
> +     queue = blkfront_req->queue;
> +     dev = queue->dev;
> +     if (dev->barrier)
> +             ring_req->operation = BLKIF_OP_WRITE_BARRIER;
> +     else if (dev->flush)
> +             ring_req->operation = BLKIF_OP_FLUSH_DISKCACHE;
> +     else
> +             return -ENOTSUP;
> +
> +     ring_req->nr_segments = 0;
> +     ring_req->sector_number = 0;
> +
> +     return 0;
> +}
> +
>  static int blkfront_queue_enqueue(struct uk_blkdev_queue *queue,
>               struct uk_blkreq *req)
>  {
> @@ -179,6 +202,8 @@ static int blkfront_queue_enqueue(struct uk_blkdev_queue 
> *queue,
>       if (req->operation == UK_BLKDEV_READ ||
>                       req->operation == UK_BLKDEV_WRITE)
>               rc = blkfront_request_write(blkfront_req, ring_req);
> +     else if (req->operation == UK_BLKDEV_FFLUSH)
> +             rc =  blkfront_request_flush(blkfront_req, ring_req);
>       else
>               rc = -EINVAL;
>  
> diff --git a/plat/xen/drivers/blk/blkfront.h b/plat/xen/drivers/blk/blkfront.h
> index ec727fc8..93d2905d 100644
> --- a/plat/xen/drivers/blk/blkfront.h
> +++ b/plat/xen/drivers/blk/blkfront.h
> @@ -89,6 +89,14 @@ struct blkfront_dev {
>       struct uk_blkdev blkdev;
>       /* Blkfront device number from Xenstore path. */
>       blkif_vdev_t    handle;
> +     /* Value which indicates that the backend can process requests with the
> +      * BLKIF_OP_WRITE_BARRIER request opcode.
> +      */
> +     int barrier;
> +     /* Value which indicates that the backend can process requests with the
> +      * BLKIF_OP_WRITE_FLUSH_DISKCACHE request opcode.
> +      */
> +     int flush;
>       /* Number of configured queues used for requests */
>       uint16_t nb_queues;
>       /* Vector of queues used for communication with backend */
> diff --git a/plat/xen/drivers/blk/blkfront_xs.c 
> b/plat/xen/drivers/blk/blkfront_xs.c
> index 69a2df9d..e93665c8 100644
> --- a/plat/xen/drivers/blk/blkfront_xs.c
> +++ b/plat/xen/drivers/blk/blkfront_xs.c
> @@ -191,6 +191,21 @@ static int blkfront_xb_get_capabilities(struct 
> blkfront_dev *blkdev)
>               return err;
>       }
>  
> +     err = xs_scanf(XBT_NIL, xendev->otherend, "feature-flush-cache",
> +                                     "%d", &blkdev->flush);
> +     if (err < 0) {
> +             uk_pr_err("Failed to read feature-flush-cache from xs: %d\n",
> +                             err);
> +             return err;
> +     }
> +
> +     err = xs_scanf(XBT_NIL, xendev->otherend, "feature-barrier",
> +                                     "%d", &blkdev->barrier);
> +     if (err < 0) {
> +             uk_pr_err("Failed to read feature-barrier from xs: %d\n", err);
> +             return err;
> +     }
> +
>       mode = xs_read(XBT_NIL, xendev->otherend, "mode");
>       if (PTRISERR(mode)) {
>               uk_pr_err("Failed to read mode from xs: %d.\n", err);
> 

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