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Re: [Qemu-devel] [RFC]virtio-blk: add disk-name device property
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [RFC]virtio-blk: add disk-name device property |
Date: |
Tue, 3 Jan 2017 16:29:50 +0000 |
User-agent: |
Mutt/1.7.1 (2016-10-04) |
On Fri, Dec 30, 2016 at 10:41:35AM +0800, Junkang Fu wrote:
> From 74e913fc41ea98d1dde692175f1e3fb6729342aa Mon Sep 17 00:00:00 2001
> From: "junkang.fjk" <address@hidden>
> 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
Did you try -device virtio-blk-pci,serial=vdabc and
/dev/disk/by-id/virtio-vdabc inside a Linux guest?
> ---
> 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 */
These bits are defined in the VIRTIO specification. In addition to
modifying QEMU and guest drivers you would also need to send a patch to
the VIRTIO Technical Committee to update the specification:
https://docs.oasis-open.org/virtio/virtio/v1.0/cs04/virtio-v1.0-cs04.html#x1-2050003
>
> /* 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
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- Re: [Qemu-devel] [RFC]virtio-blk: add disk-name device property,
Stefan Hajnoczi <=
Re: [Qemu-devel] [RFC]virtio-blk: add disk-name device property, Junkang Fu, 2017/01/05
Re: [Qemu-devel] [RFC]virtio-blk: add disk-name device property, Junkang Fu, 2017/01/05