[Qemu-devel] [PATCH] virtio-blk: add default serial id

[Qemu-devel] [PATCH] virtio-blk: add default serial id

[Dave Young]

For virtio block device, if user does not specify the serial attribute,
There will be not serial availabe, this is not convinient for identify
the disk.

Doing something similar to ide disks, add a "VD0000?" default serial
number if user does not specify it.

Signed-off-by: Dave Young <dyoung@redhat.com>
---
 hw/virtio-blk.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

--- qemu.orig/hw/virtio-blk.c
+++ qemu/hw/virtio-blk.c
@@ -22,6 +22,7 @@
 # include <scsi/sg.h>
 #endif
 
+#define DEFAULT_VIRTIO_BLK_SERIAL_LEN 8
 typedef struct VirtIOBlock
 {
     VirtIODevice vdev;
@@ -33,6 +34,7 @@ typedef struct VirtIOBlock
     VirtIOBlkConf *blk;
     unsigned short sector_mask;
     DeviceState *qdev;
+    int drive_serial;
 } VirtIOBlock;
 
 static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)
@@ -364,6 +366,7 @@ static void virtio_blk_handle_request(Vi
     MultiReqBuffer *mrb)
 {
     uint32_t type;
+    char serial[DEFAULT_VIRTIO_BLK_SERIAL_LEN];
 
     if (req->elem.out_num < 1 || req->elem.in_num < 1) {
         error_report("virtio-blk missing headers");
@@ -388,12 +391,14 @@ static void virtio_blk_handle_request(Vi
     } else if (type & VIRTIO_BLK_T_GET_ID) {
         VirtIOBlock *s = req->dev;
 
+        snprintf(serial, DEFAULT_VIRTIO_BLK_SERIAL_LEN,
+                 "VD%05d", s->drive_serial);
         /*
          * NB: per existing s/n string convention the string is
          * terminated by '\0' only when shorter than buffer.
          */
         strncpy(req->elem.in_sg[0].iov_base,
-                s->blk->serial ? s->blk->serial : "",
+                s->blk->serial ? s->blk->serial : serial,
                 MIN(req->elem.in_sg[0].iov_len, VIRTIO_BLK_ID_BYTES));
         virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
         g_free(req);
@@ -611,6 +616,7 @@ static const BlockDevOps virtio_block_op
 
 VirtIODevice *virtio_blk_init(DeviceState *dev, VirtIOBlkConf *blk)
 {
+    static int drive_serial = 1;
     VirtIOBlock *s;
     static int virtio_blk_id;
 
@@ -632,6 +638,7 @@ VirtIODevice *virtio_blk_init(DeviceStat
                                           sizeof(struct virtio_blk_config),
                                           sizeof(VirtIOBlock));
 
+    s->drive_serial = drive_serial++;
     s->vdev.get_config = virtio_blk_update_config;
     s->vdev.set_config = virtio_blk_set_config;
     s->vdev.get_features = virtio_blk_get_features;

Re: [Qemu-devel] [PATCH] virtio-blk: add default serial id

[Eric Blake]

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On 09/20/2012 01:17 AM, Dave Young wrote:
> For virtio block device, if user does not specify the serial attribute,
> There will be not serial availabe, this is not convinient for identify

s/not serial availabe/no serial available/
s/convinient/convenient/
s/identify/identifying/

> the disk.
> 
> Doing something similar to ide disks, add a "VD0000?" default serial
> number if user does not specify it.
> 
> Signed-off-by: Dave Young <dyoung@redhat.com>
> ---

>  
> +#define DEFAULT_VIRTIO_BLK_SERIAL_LEN 8

> +    char serial[DEFAULT_VIRTIO_BLK_SERIAL_LEN];
>  
>      if (req->elem.out_num < 1 || req->elem.in_num < 1) {
>          error_report("virtio-blk missing headers");
> @@ -388,12 +391,14 @@ static void virtio_blk_handle_request(Vi
>      } else if (type & VIRTIO_BLK_T_GET_ID) {
>          VirtIOBlock *s = req->dev;
>  
> +        snprintf(serial, DEFAULT_VIRTIO_BLK_SERIAL_LEN,
> +                 "VD%05d", s->drive_serial);

So if I cycle through hotplug and unplug for 100000 times, my string
will now be silently truncated, and I can end up with disks with shared
serial numbers?

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


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