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

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

[Junkang Fu]

[-- Attachment #1: Type: text/plain, Size: 3929 bytes --]

>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

[-- Attachment #2: 0001-virtio-blk-add-disk-name-device-property.patch --]
[-- Type: application/octet-stream, Size: 3913 bytes --]

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

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

[Cao jin]

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
> 
> 

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

[Junkang Fu]

Thank you for pointing out this, i'll resend the patch if my suggestion is
acceptted.

2016-12-30 15:34 GMT+08:00 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
> >
> >
>
>
>
>
>

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

[Stefan Hajnoczi]

[-- Attachment #1: Type: text/plain, Size: 4712 bytes --]

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" <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

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

[Junkang Fu]

Thank you. -device virtio-blk-pci,serial=vdabc will solve my problem to
some extent.

2017-01-04 0:29 GMT+08:00 Stefan Hajnoczi <stefanha@gmail.com>:

> 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" <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
>
> 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
>
>
>

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

[Eric Blake]

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On 12/29/2016 08:41 PM, 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.

It's not really libvirt's fault.  The libvirt XML names are for
convenience, but nothing on the host side requires the guest to pick the
same naming scheme as the host.

I guess your proposal is to enhance the virtio spec such that clients
that are new enough to honor the new addition to the virtio spec will
change their name-picking algorithm to use the name provided by the
host, rather than their current approach of picking whatever name they
feel like, and then enhance libvirt to pass the XML name on down to the
guest?  It might work, but as others have pointed out, it will require a
virtio spec change first.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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

[Stefan Hajnoczi]

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On Tue, Jan 03, 2017 at 10:53:06AM -0600, Eric Blake wrote:
> On 12/29/2016 08:41 PM, 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.
> 
> It's not really libvirt's fault.  The libvirt XML names are for
> convenience, but nothing on the host side requires the guest to pick the
> same naming scheme as the host.
> 
> I guess your proposal is to enhance the virtio spec such that clients
> that are new enough to honor the new addition to the virtio spec will
> change their name-picking algorithm to use the name provided by the
> host, rather than their current approach of picking whatever name they
> feel like, and then enhance libvirt to pass the XML name on down to the
> guest?  It might work, but as others have pointed out, it will require a
> virtio spec change first.

This change is unnecessary.  The -device virtio-blk-pci,serial= property
already exists for this purpose.

Stefan

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

[Yang Zhang]

On 2017/1/4 22:44, Stefan Hajnoczi wrote:
> On Tue, Jan 03, 2017 at 10:53:06AM -0600, Eric Blake wrote:
>> On 12/29/2016 08:41 PM, 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.
>>
>> It's not really libvirt's fault.  The libvirt XML names are for
>> convenience, but nothing on the host side requires the guest to pick the
>> same naming scheme as the host.
>>
>> I guess your proposal is to enhance the virtio spec such that clients
>> that are new enough to honor the new addition to the virtio spec will
>> change their name-picking algorithm to use the name provided by the
>> host, rather than their current approach of picking whatever name they
>> feel like, and then enhance libvirt to pass the XML name on down to the
>> guest?  It might work, but as others have pointed out, it will require a
>> virtio spec change first.
>
> This change is unnecessary.  The -device virtio-blk-pci,serial= property
> already exists for this purpose.

how about the /dev/vdabc? I guess lots of people prefer to use it 
instead of /dev/disk/by-id/xxx?

-- 
Yang
Alibaba Cloud Computing

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

[Fam Zheng]

On Thu, 01/12 09:22, Yang Zhang wrote:
> On 2017/1/4 22:44, Stefan Hajnoczi wrote:
> > On Tue, Jan 03, 2017 at 10:53:06AM -0600, Eric Blake wrote:
> > > On 12/29/2016 08:41 PM, 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.
> > > 
> > > It's not really libvirt's fault.  The libvirt XML names are for
> > > convenience, but nothing on the host side requires the guest to pick the
> > > same naming scheme as the host.
> > > 
> > > I guess your proposal is to enhance the virtio spec such that clients
> > > that are new enough to honor the new addition to the virtio spec will
> > > change their name-picking algorithm to use the name provided by the
> > > host, rather than their current approach of picking whatever name they
> > > feel like, and then enhance libvirt to pass the XML name on down to the
> > > guest?  It might work, but as others have pointed out, it will require a
> > > virtio spec change first.
> > 
> > This change is unnecessary.  The -device virtio-blk-pci,serial= property
> > already exists for this purpose.
> 
> how about the /dev/vdabc? I guess lots of people prefer to use it instead of
> /dev/disk/by-id/xxx?

I disagree. Using /dev/sdX has exactly the same issue and that's why fstab and
boot loader etc almost always use UUID or disk label by default because they are
more stable.

Fam

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

[Yang Zhang]

On 2017/1/12 10:22, Fam Zheng wrote:
> On Thu, 01/12 09:22, Yang Zhang wrote:
>> On 2017/1/4 22:44, Stefan Hajnoczi wrote:
>>> On Tue, Jan 03, 2017 at 10:53:06AM -0600, Eric Blake wrote:
>>>> On 12/29/2016 08:41 PM, 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.
>>>>
>>>> It's not really libvirt's fault.  The libvirt XML names are for
>>>> convenience, but nothing on the host side requires the guest to pick the
>>>> same naming scheme as the host.
>>>>
>>>> I guess your proposal is to enhance the virtio spec such that clients
>>>> that are new enough to honor the new addition to the virtio spec will
>>>> change their name-picking algorithm to use the name provided by the
>>>> host, rather than their current approach of picking whatever name they
>>>> feel like, and then enhance libvirt to pass the XML name on down to the
>>>> guest?  It might work, but as others have pointed out, it will require a
>>>> virtio spec change first.
>>>
>>> This change is unnecessary.  The -device virtio-blk-pci,serial= property
>>> already exists for this purpose.
>>
>> how about the /dev/vdabc? I guess lots of people prefer to use it instead of
>> /dev/disk/by-id/xxx?
>
> I disagree. Using /dev/sdX has exactly the same issue and that's why fstab and
> boot loader etc almost always use UUID or disk label by default because they are
> more stable.

I mean does it also change the /dev/sdX to the name specified in 
serial=sdX or it just show the name under /dev/disk/by-id/


-- 
Yang
Alibaba Cloud Computing

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

[Fam Zheng]

On Thu, 01/12 15:39, Yang Zhang wrote:
> On 2017/1/12 10:22, Fam Zheng wrote:
> > On Thu, 01/12 09:22, Yang Zhang wrote:
> > > On 2017/1/4 22:44, Stefan Hajnoczi wrote:
> > > > On Tue, Jan 03, 2017 at 10:53:06AM -0600, Eric Blake wrote:
> > > > > On 12/29/2016 08:41 PM, 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.
> > > > > 
> > > > > It's not really libvirt's fault.  The libvirt XML names are for
> > > > > convenience, but nothing on the host side requires the guest to pick the
> > > > > same naming scheme as the host.
> > > > > 
> > > > > I guess your proposal is to enhance the virtio spec such that clients
> > > > > that are new enough to honor the new addition to the virtio spec will
> > > > > change their name-picking algorithm to use the name provided by the
> > > > > host, rather than their current approach of picking whatever name they
> > > > > feel like, and then enhance libvirt to pass the XML name on down to the
> > > > > guest?  It might work, but as others have pointed out, it will require a
> > > > > virtio spec change first.
> > > > 
> > > > This change is unnecessary.  The -device virtio-blk-pci,serial= property
> > > > already exists for this purpose.
> > > 
> > > how about the /dev/vdabc? I guess lots of people prefer to use it instead of
> > > /dev/disk/by-id/xxx?
> > 
> > I disagree. Using /dev/sdX has exactly the same issue and that's why fstab and
> > boot loader etc almost always use UUID or disk label by default because they are
> > more stable.
> 
> I mean does it also change the /dev/sdX to the name specified in serial=sdX
> or it just show the name under /dev/disk/by-id/

I was saying on real hardware, sata disks can have unstable /dev/sdX naming
across reboots if you add or remove disks on the controller, or add or remove
HBA.

Fam

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

[Stefan Hajnoczi]

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On Thu, Jan 12, 2017 at 10:22:12AM +0800, Fam Zheng wrote:
> On Thu, 01/12 09:22, Yang Zhang wrote:
> > On 2017/1/4 22:44, Stefan Hajnoczi wrote:
> > > On Tue, Jan 03, 2017 at 10:53:06AM -0600, Eric Blake wrote:
> > > > On 12/29/2016 08:41 PM, 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.
> > > > 
> > > > It's not really libvirt's fault.  The libvirt XML names are for
> > > > convenience, but nothing on the host side requires the guest to pick the
> > > > same naming scheme as the host.
> > > > 
> > > > I guess your proposal is to enhance the virtio spec such that clients
> > > > that are new enough to honor the new addition to the virtio spec will
> > > > change their name-picking algorithm to use the name provided by the
> > > > host, rather than their current approach of picking whatever name they
> > > > feel like, and then enhance libvirt to pass the XML name on down to the
> > > > guest?  It might work, but as others have pointed out, it will require a
> > > > virtio spec change first.
> > > 
> > > This change is unnecessary.  The -device virtio-blk-pci,serial= property
> > > already exists for this purpose.
> > 
> > how about the /dev/vdabc? I guess lots of people prefer to use it instead of
> > /dev/disk/by-id/xxx?
> 
> I disagree. Using /dev/sdX has exactly the same issue and that's why fstab and
> boot loader etc almost always use UUID or disk label by default because they are
> more stable.

Right, /dev/sdX shouldn't be used in configuration files or other
persistent state.

Try cat /etc/fstab on your own system.

On my system there are no /dev/sdX paths in /etc/fstab, only UUIDs and
LVM logical volume paths.

Stefan

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

[Junkang Fu]

You got it, that's exactly what I mean.Thank you for your advise.

2017-01-04 0:53 GMT+08:00 Eric Blake <eblake@redhat.com>:

> On 12/29/2016 08:41 PM, 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.
>
> It's not really libvirt's fault.  The libvirt XML names are for
> convenience, but nothing on the host side requires the guest to pick the
> same naming scheme as the host.
>
> I guess your proposal is to enhance the virtio spec such that clients
> that are new enough to honor the new addition to the virtio spec will
> change their name-picking algorithm to use the name provided by the
> host, rather than their current approach of picking whatever name they
> feel like, and then enhance libvirt to pass the XML name on down to the
> guest?  It might work, but as others have pointed out, it will require a
> virtio spec change first.
>
> --
> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
>
>