Re: [Minios-devel] [UNIKRAFT PATCH v3 12/17] plat/xen/drivers/blk: Read device capabilities

[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 function which reads the capabilities
> from Xenstore, after connection to backend.
> 
> Signed-off-by: Roxana Nicolescu <nicolescu.roxana1996@xxxxxxxxx>
> ---
>  plat/xen/drivers/blk/blkfront_xs.c | 43 ++++++++++++++++++++++++++++++
>  1 file changed, 43 insertions(+)
> 
> diff --git a/plat/xen/drivers/blk/blkfront_xs.c 
> b/plat/xen/drivers/blk/blkfront_xs.c
> index 7775f7ec..732e92f0 100644
> --- a/plat/xen/drivers/blk/blkfront_xs.c
> +++ b/plat/xen/drivers/blk/blkfront_xs.c
> @@ -165,6 +165,43 @@ out:
>       return err;
>  }
>  
> +/*
> + * Get device capabilities (sector_size, etc)
> + * from the backend after it switched to Connected State.
> + */
> +static int blkfront_xb_get_capabilities(struct blkfront_dev *blkdev)
> +{
> +     struct xenbus_device *xendev;
> +     char *mode;
> +     int err = 0;
> +
> +     UK_ASSERT(blkdev != NULL);
> +     xendev = blkdev->xendev;
> +     err = xs_scanf(XBT_NIL, xendev->otherend, "sectors",
> +             "%lu", &blkdev->blkdev.capabilities.sectors);
> +     if (err < 0) {
> +             uk_pr_err("Failed to read nb_sectors from xs: %d\n", err);
> +             return err;
> +     }
> +
> +     err = xs_scanf(XBT_NIL, xendev->otherend, "sector-size",
> +                     "%lu", &blkdev->blkdev.capabilities.ssize);
> +     if (err < 0) {
> +             uk_pr_err("Failed to read ssize 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);
> +             return PTR2ERR(mode);
> +     }
> +
> +     blkdev->blkdev.capabilities.mode = (*mode == 'r') ? O_RDONLY : O_RDWR;
> +
> +     free(mode);
> +     return 0;
> +}
>  
>  /* Write info for a specific queue in xenstore.
>   * If there is only one queue, the path does not
> @@ -452,6 +489,12 @@ int blkfront_xb_connect(struct blkfront_dev *blkdev)
>       if (err)
>               goto err;
>  
> +     err = blkfront_xb_get_capabilities(blkdev);
> +     if (err) {
> +             uk_pr_err("Failed to extract info from backend: %d.\n", err);
> +             goto err;
> +     }
> +
>  err:
>       return err;
>  }
> 

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