Re: [PATCH v3] virtio_blk: Add support for lifetime feature

Greg KH
2021-12-23T10:47:59Z

[note, your original post had the to: line messed up, which caused any
response to this to not work well in many email clients, this is a
resend...]

On Tue, Dec 07, 2021 at 10:55:17AM -0700, Enrico Granata wrote:
> From: Enrico Granata <egranata@google.com>
>
> 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 new attributes to the
> sysfs entry for virtio_blk:
> * pre_eol_info
> * life_time_a
> * life_time_b
>
> which are defined in the VirtIO specification.
>
> Signed-off-by: Enrico Granata <egranata@google.com>
> ---
> Changes in v3:
> - Split life_time attribute in two
> - Made VirtIO specification independent of eMMC
> - Adopted newer APIs to mirror surrounding code
>
> drivers/block/virtio_blk.c | 106 ++++++++++++++++++++++++++++++--
> include/uapi/linux/virtio_blk.h | 11 ++++
> 2 files changed, 113 insertions(+), 4 deletions(-)

You seem to be missing new Documentation/ABI/ entries for these new
sysfs files you are adding. That is required.

>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 6ae38776e30e..c50f5d9a173b 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -213,7 +213,7 @@ static blk_status_t virtblk_setup_cmd(struct virtio_device *vdev,
> struct virtblk_req *vbr)
> {
> bool unmap = false;
> - u32 type;
> + u32 type = 0;

VIRTIO_BLK_T_GET_ID?

And why isn't this an enum?

>
> vbr->out_hdr.sector = 0;
>
> @@ -239,14 +239,14 @@ static blk_status_t virtblk_setup_cmd(struct virtio_device *vdev,
> unmap = !(req->cmd_flags & REQ_NOUNMAP);
> break;
> case REQ_OP_DRV_IN:
> - type = VIRTIO_BLK_T_GET_ID;
> - break;
> + break; /* type already set for custom requests */
> default:
> WARN_ON_ONCE(1);
> return BLK_STS_IOERR;
> }
>
> - vbr->out_hdr.type = cpu_to_virtio32(vdev, type);
> + if (req_op(req) != REQ_OP_DRV_IN)
> + vbr->out_hdr.type = cpu_to_virtio32(vdev, type);
> vbr->out_hdr.ioprio = cpu_to_virtio32(vdev, req_get_ioprio(req));
>
> if (type == VIRTIO_BLK_T_DISCARD || type == VIRTIO_BLK_T_WRITE_ZEROES) {
> @@ -374,11 +374,14 @@ 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 *vbr;
> int err;
>
> req = blk_mq_alloc_request(q, REQ_OP_DRV_IN, 0);
> if (IS_ERR(req))
> return PTR_ERR(req);
> + vbr = blk_mq_rq_to_pdu(req);
> + vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev, VIRTIO_BLK_T_GET_ID);
>
> err = blk_rq_map_kern(q, req, id_str, VIRTIO_BLK_ID_BYTES, GFP_KERNEL);
> if (err)
> @@ -391,6 +394,35 @@ 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 *vbr;
> + int err;
> +
> + if (!virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_LIFETIME))
> + return -EOPNOTSUPP;
> +
> + req = blk_mq_alloc_request(q, REQ_OP_DRV_IN, 0);
> + if (IS_ERR(req))
> + return PTR_ERR(req);
> + vbr = blk_mq_rq_to_pdu(req);
> + vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev, 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_mq_free_request(req);
> + return err;
> +}
> +
> +
> static void virtblk_get(struct virtio_blk *vblk)
> {
> refcount_inc(&vblk->refs);
> @@ -499,6 +531,68 @@ 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)

Please fix your editor to properly set the tab spacing for kernel
changes (hint 8).

> +{
> + 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);

That's crazy, and wrong here, please remove. It has nothing to do with
this function operating properly or not.

> +
> + err = virtblk_get_lifetime(disk, &lft);
> + if (err)
> + return 0;

Please return the error.

> +
> + return sprintf(buf, "0x%02x\n", le16_to_cpu(lft.pre_eol_info));

sysfs_emit() for all new sysfs show functions.

> +}

Why are you mixing sysfs files with a new uapi function in the same
patch? Shouldn't this be at least 2 patches as part of a series?

thanks,

greg k-h