Re: [PATCH] virtio_blk: print capacity at probe time

[Stefan Hajnoczi]

On Wed, Jan 3, 2018 at 4:03 PM, Stefan Hajnoczi <stefanha@xxxxxxxxxx> wrote:
> Print the capacity of the block device when the driver is probed.  Many
> users expect this since SCSI disks (sd) do it.  Moreover, kernel dmesg
> output is the primary source of troubleshooting information so it's
> helpful to include the disk size there.
>
> The capacity is already printed by virtio_blk when a resize event
> occurs.  Extract the code and reuse it from virtblk_probe().
>
> This patch also adds the block device name to the message so it can be
> correlated with a specific device:
>
>   virtio_blk virtio0: [vda] 20971520 512-byte logical blocks (10.7 GB/10.0 GiB)
>
> Cc: Rodrigo A B Freire <rfreire@xxxxxxxxxx>
> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Signed-off-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>
> ---
>  drivers/block/virtio_blk.c | 32 +++++++++++++++-----------------
>  1 file changed, 15 insertions(+), 17 deletions(-)

Ping?

> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 68846897d213..787cd2a10b0b 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -373,14 +373,12 @@ static ssize_t virtblk_serial_show(struct device *dev,
>
>  static DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
>
> -static void virtblk_config_changed_work(struct work_struct *work)
> +/* The queue's logical block size must be set before calling this */
> +static void virtblk_update_capacity(struct virtio_blk *vblk, bool resize)
>  {
> -       struct virtio_blk *vblk =
> -               container_of(work, struct virtio_blk, config_work);
>         struct virtio_device *vdev = vblk->vdev;
>         struct request_queue *q = vblk->disk->queue;
>         char cap_str_2[10], cap_str_10[10];
> -       char *envp[] = { "RESIZE=1", NULL };
>         unsigned long long nblocks;
>         u64 capacity;
>
> @@ -402,13 +400,24 @@ static void virtblk_config_changed_work(struct work_struct *work)
>                         STRING_UNITS_10, cap_str_10, sizeof(cap_str_10));
>
>         dev_notice(&vdev->dev,
> -                  "new size: %llu %d-byte logical blocks (%s/%s)\n",
> +                  "[%s] %s%llu %d-byte logical blocks (%s/%s)\n",
> +                  vblk->disk->disk_name,
> +                  resize ? "new size: " : "",
>                    nblocks,
>                    queue_logical_block_size(q),
>                    cap_str_10,
>                    cap_str_2);
>
>         set_capacity(vblk->disk, capacity);
> +}
> +
> +static void virtblk_config_changed_work(struct work_struct *work)
> +{
> +       struct virtio_blk *vblk =
> +               container_of(work, struct virtio_blk, config_work);
> +       char *envp[] = { "RESIZE=1", NULL };
> +
> +       virtblk_update_capacity(vblk, true);
>         revalidate_disk(vblk->disk);
>         kobject_uevent_env(&disk_to_dev(vblk->disk)->kobj, KOBJ_CHANGE, envp);
>  }
> @@ -621,7 +630,6 @@ static int virtblk_probe(struct virtio_device *vdev)
>         struct request_queue *q;
>         int err, index;
>
> -       u64 cap;
>         u32 v, blk_size, sg_elems, opt_io_size;
>         u16 min_io_size;
>         u8 physical_block_exp, alignment_offset;
> @@ -719,17 +727,6 @@ static int virtblk_probe(struct virtio_device *vdev)
>         if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
>                 set_disk_ro(vblk->disk, 1);
>
> -       /* Host must always specify the capacity. */
> -       virtio_cread(vdev, struct virtio_blk_config, capacity, &cap);
> -
> -       /* If capacity is too big, truncate with warning. */
> -       if ((sector_t)cap != cap) {
> -               dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
> -                        (unsigned long long)cap);
> -               cap = (sector_t)-1;
> -       }
> -       set_capacity(vblk->disk, cap);
> -
>         /* We can handle whatever the host told us to handle. */
>         blk_queue_max_segments(q, vblk->sg_elems-2);
>
> @@ -780,6 +777,7 @@ static int virtblk_probe(struct virtio_device *vdev)
>         if (!err && opt_io_size)
>                 blk_queue_io_opt(q, blk_size * opt_io_size);
>
> +       virtblk_update_capacity(vblk, false);
>         virtio_device_ready(vdev);
>
>         device_add_disk(&vdev->dev, vblk->disk);
> --
> 2.14.3
>
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