Re: [Qemu-devel] [RFC]virtio-blk: add disk-name device property

[Cao jin <caoj.fnst@cn.fujitsu.com>]

As I know, this is not a good way to submit a patch. You need to read
the guideline first: http://wiki.qemu.org/Contribute/SubmitAPatch

-- 
Sincerely,
Cao jin

On 12/30/2016 10:41 AM, Junkang Fu wrote:
>>From 74e913fc41ea98d1dde692175f1e3fb6729342aa Mon Sep 17 00:00:00 2001
> From: "junkang.fjk" <junkang.fjk@alibaba-inc.com>
> Date: Wed, 24 Aug 2016 19:36:53 +0800
> Subject: [PATCH] virtio-blk: add disk-name device property
> 
> Current virtio-blk disk name(ex. /dev/vdb) has nothing to do with the
> target dev
> name specified in libvirt xml file. For example, we may get disk name
> /dev/vdb in
> VM while target dev specified in libvirt xml is vdc. This may lead to a
> little trouble
> to find out the relationship between the disk name in VM and somewhere out
> of
> VM, for example in the control board of Public cloud service providers. I
> suggest
> if Qemu could add a VIRTIO_BLK_F_DISK_NAME feature, with
> VIRTIO_BLK_F_DISK_NAME
> capable Qemu and virtio-blk frontend drivers, disk name in the vm can be
> specified
> as follows:
>         -device virtio-blk-pci,disk-name=vdabc
> 
> ---
>  hw/block/virtio-blk.c                       | 5 +++++
>  include/hw/virtio/virtio-blk.h              | 1 +
>  include/standard-headers/linux/virtio_blk.h | 6 ++++++
>  3 files changed, 12 insertions(+)
> 
> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> index 331d766..4039fb9 100644
> --- a/hw/block/virtio-blk.c
> +++ b/hw/block/virtio-blk.c
> @@ -716,6 +716,8 @@ static void virtio_blk_update_config(VirtIODevice
> *vdev, uint8_t *config)
>      blkcfg.alignment_offset = 0;
>      blkcfg.wce = blk_enable_write_cache(s->blk);
>      virtio_stw_p(vdev, &blkcfg.num_queues, s->conf.num_queues);
> +    if (s->disk_name)
> +        strncpy((char *)blkcfg.disk_name, s->disk_name, DISK_NAME_LEN);
>      memcpy(config, &blkcfg, sizeof(struct virtio_blk_config));
>  }
> @@ -740,6 +742,8 @@ static uint64_t virtio_blk_get_features(VirtIODevice
> *vdev, uint64_t features,
>      virtio_add_feature(&features, VIRTIO_BLK_F_GEOMETRY);
>      virtio_add_feature(&features, VIRTIO_BLK_F_TOPOLOGY);
>      virtio_add_feature(&features, VIRTIO_BLK_F_BLK_SIZE);
> +    virtio_add_feature(&features, VIRTIO_BLK_F_DISK_NAME);
> +
>      if (virtio_has_feature(features, VIRTIO_F_VERSION_1)) {
>          if (s->conf.scsi) {
>              error_setg(errp, "Please set scsi=off for virtio-blk devices
> in order to use virtio 1.0");
> @@ -970,6 +974,7 @@ static Property virtio_blk_properties[] = {
>      DEFINE_PROP_BIT("request-merging", VirtIOBlock, conf.request_merging,
> 0,
>                      true),
>      DEFINE_PROP_UINT16("num-queues", VirtIOBlock, conf.num_queues, 1),
> +    DEFINE_PROP_STRING("disk-name", VirtIOBlock, disk_name),
>      DEFINE_PROP_END_OF_LIST(),
>  };
> 
> diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h
> index 180bd8d..003e810 100644
> --- a/include/hw/virtio/virtio-blk.h
> +++ b/include/hw/virtio/virtio-blk.h
> @@ -56,6 +56,7 @@ typedef struct VirtIOBlock {
>      bool dataplane_disabled;
>      bool dataplane_started;
>      struct VirtIOBlockDataPlane *dataplane;
> +    char *disk_name;
>  } VirtIOBlock;
> 
>  typedef struct VirtIOBlockReq {
> diff --git a/include/standard-headers/linux/virtio_blk.h
> b/include/standard-headers/linux/virtio_blk.h
> index ab16ec5..1f5d89d 100644
> --- a/include/standard-headers/linux/virtio_blk.h
> +++ b/include/standard-headers/linux/virtio_blk.h
> @@ -38,6 +38,7 @@
>  #define VIRTIO_BLK_F_BLK_SIZE  6   /* Block size of disk is available*/
>  #define VIRTIO_BLK_F_TOPOLOGY  10  /* Topology information is available */
>  #define VIRTIO_BLK_F_MQ        12  /* support more than one vq */
> +#define VIRTIO_BLK_F_DISK_NAME  13      /* specify /dev/xxx name */
> 
>  /* Legacy feature bits */
>  #ifndef VIRTIO_BLK_NO_LEGACY
> @@ -51,6 +52,9 @@
> 
>  #define VIRTIO_BLK_ID_BYTES    20  /* ID string length */
> 
> +/* micro defined in kernel genhd.h */
> +#define DISK_NAME_LEN 32
> +
>  struct virtio_blk_config {
>     /* The capacity (in 512-byte sectors). */
>     uint64_t capacity;
> @@ -84,6 +88,8 @@ struct virtio_blk_config {
> 
>     /* number of vqs, only available when VIRTIO_BLK_F_MQ is set */
>     uint16_t num_queues;
> +
> +   uint8_t disk_name[DISK_NAME_LEN];
>  } QEMU_PACKED;
> 
>  /*
> --
> 1.9.4
> 
>