On Tue, Mar 30, 2021 at 11:16:02PM +0000, Enrico Granata wrote:
> The VirtIO TC has adopted a new feature in virtio-blk enabling
> discovery of lifetime information.
>
> This commit adds support for the VIRTIO_BLK_T_LIFETIME command
> to the virtio_blk driver, and adds two new attributes to the
> sysfs entry for virtio_blk:
> * pre_eol_info
> * life_time
>
> which are defined in the same manner as the files of the same name
> for the eMMC driver, in line with the VirtIO specification.
>
> Signed-off-by: Enrico Granata <egranata@xxxxxxxxxx>
> ---
> drivers/block/virtio_blk.c | 76 ++++++++++++++++++++++++++++++++-
> include/uapi/linux/virtio_blk.h | 11 +++++
> 2 files changed, 86 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index b9fa3ef5b57c..1fc0ec000b4f 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -246,7 +246,7 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
> unmap = !(req->cmd_flags & REQ_NOUNMAP);
> break;
> case REQ_OP_DRV_IN:
> - type = VIRTIO_BLK_T_GET_ID;
> + type = vbr->out_hdr.type;
This patch changes the endianness of vbr->out_hdr.type from
virtio-endian to cpu endian before virtio_queue_rq. That is error-prone
because someone skimming through the code will see some accesses with
cpu_to_virtio32() and others without it. They would have to audit the
code carefully to understand what is going on.
The following is cleaner:
case REQ_OP_DRV_IN:
break; /* type already set for custom requests */
...
if (req_op(req) != REQ_OP_DRV_IN)
vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev, type);
Now vbr->out_hdr.type is virtio-endian everywhere. If we need to support
REQ_OP_DRV_OUT in the future it can use the same approach.
virtblk_get_id() and virtblk_get_lifetime() would be updated like this:
vbreq->out_hdr.type = cpu_to_virtio32(VIRTIO_BLK_T_GET_*);
> break;
> default:
> WARN_ON_ONCE(1);
> @@ -310,11 +310,14 @@ static int virtblk_get_id(struct gendisk *disk, char *id_str)
> struct virtio_blk *vblk = disk->private_data;
> struct request_queue *q = vblk->disk->queue;
> struct request *req;
> + struct virtblk_req *vbreq;
It's called vbr elsewhere in the driver. It would be nice to keep naming
consistent.
> int err;
>
> req = blk_get_request(q, REQ_OP_DRV_IN, 0);
> if (IS_ERR(req))
> return PTR_ERR(req);
> + vbreq = blk_mq_rq_to_pdu(req);
> + vbreq->out_hdr.type = VIRTIO_BLK_T_GET_ID;
>
> err = blk_rq_map_kern(q, req, id_str, VIRTIO_BLK_ID_BYTES, GFP_KERNEL);
> if (err)
> @@ -327,6 +330,34 @@ static int virtblk_get_id(struct gendisk *disk, char *id_str)
> return err;
> }
>
> +static int virtblk_get_lifetime(struct gendisk *disk, struct virtio_blk_lifetime *lifetime)
> +{
> + struct virtio_blk *vblk = disk->private_data;
> + struct request_queue *q = vblk->disk->queue;
> + struct request *req;
> + struct virtblk_req *vbreq;
> + int err;
> +
> + if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_LIFETIME))
> + return -EOPNOTSUPP;
> +
> + req = blk_get_request(q, REQ_OP_DRV_IN, 0);
> + if (IS_ERR(req))
> + return PTR_ERR(req);
> + vbreq = blk_mq_rq_to_pdu(req);
> + vbreq->out_hdr.type = VIRTIO_BLK_T_GET_LIFETIME;
> +
> + err = blk_rq_map_kern(q, req, lifetime, sizeof(*lifetime), GFP_KERNEL);
> + if (err)
> + goto out;
> +
> + blk_execute_rq(vblk->disk, req, false);
> + err = blk_status_to_errno(virtblk_result(blk_mq_rq_to_pdu(req)));
> +out:
> + blk_put_request(req);
> + return err;
> +}
> +
> static void virtblk_get(struct virtio_blk *vblk)
> {
> refcount_inc(&vblk->refs);
> @@ -435,6 +466,46 @@ static ssize_t serial_show(struct device *dev,
>
> static DEVICE_ATTR_RO(serial);
>
> +static ssize_t pre_eol_info_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct gendisk *disk = dev_to_disk(dev);
> + struct virtio_blk_lifetime lft;
> + int err;
> +
> + /* sysfs gives us a PAGE_SIZE buffer */
> + BUILD_BUG_ON(sizeof(lft) >= PAGE_SIZE);
Why is this necessary? In serial_show() it protects against a buffer
overflow. That's not the case here since sprintf() is used to write to
buf and the size of lft doesn't really matter.
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