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Re: [libvirt] [PATCH 3/5] disk geometry



On Wed, Jun 24, 2009 at 11:17:49AM +0200, Henrik Persson wrote:
> Reads the disk geometry to be able to align disk partitions on cylinder boundries.
> Msdos partition tables really like this stuff.

> --- libvirt-0.6.4.org/src/parthelper.c	2009-06-23 13:07:38.167048000 +0200
> +++ libvirt-0.6.4/src/parthelper.c	2009-06-23 17:13:27.636892000 +0200
> @@ -41,14 +41,22 @@
>  # define PED_PARTITION_PROTECTED 0
>  #endif
>  
> +enum diskCommand {
> +    DISK_LAYOUT = 0,
> +    DISK_GEOMETRY
> +};
> +
>  int main(int argc, char **argv)
>  {
>      PedDevice *dev;
>      PedDisk *disk;
>      PedPartition *part;
> +    int cmd = DISK_LAYOUT;
>  
> -    if (argc !=  2) {
> -        fprintf(stderr, "syntax: %s DEVICE\n", argv[0]);
> +    if (argc ==  3 && !strcmp(argv[2], "-g")) {
> +        cmd = DISK_GEOMETRY;
> +    } else if (argc != 2) {
> +        fprintf(stderr, "syntax: %s DEVICE [-g]\n", argv[0]);
>          return 1;
>      }
>  
> @@ -57,6 +65,15 @@ int main(int argc, char **argv)
>          return 2;
>      }
>  
> +    /* return the geometry of the disk and then exit */
> +    if(cmd == DISK_GEOMETRY) {
> +        printf("%d%c%d%c%d%c%",
> +               dev->hw_geom.cylinders, '\0',
> +               dev->hw_geom.heads, '\0',
> +               dev->hw_geom.sectors, '\0');
> +        return 0;
> +    }
> +
>      if ((disk = ped_disk_new(dev)) == NULL) {
>          fprintf(stderr, "unable to access disk %s\n", argv[1]);
>          return 2;
> --- libvirt-0.6.4.org/src/storage_conf.h	2009-06-23 16:46:47.946019000 +0200
> +++ libvirt-0.6.4/src/storage_conf.h	2009-06-23 17:38:23.705006000 +0200
> @@ -188,6 +188,13 @@ struct _virStoragePoolSourceDevice {
>      virStoragePoolSourceDeviceExtentPtr freeExtents;
>      char *path;
>      int format;     /* Pool specific source format */
> +    /* When the source device is a physical disk,
> +       the geometry data is needed */
> +    struct _geometry {
> +        int cyliders;
> +        int heads;
> +        int sectors;
> +    } geometry;
>  };
>  
>  
> --- libvirt-0.6.4.org/src/storage_backend_disk.c	2009-06-23 16:46:47.957024000 +0200
> +++ libvirt-0.6.4/src/storage_backend_disk.c	2009-06-23 17:47:35.118203000 +0200
> @@ -303,6 +303,35 @@ virStorageBackendDiskReadPartitions(virC
>                                         vol);
>  }
>  
> +static int
> +virStorageBackendDiskMakePoolGeometry(virConnectPtr conn ATTRIBUTE_UNUSED,
> +                                     virStoragePoolObjPtr pool,
> +                                     size_t ntok ATTRIBUTE_UNUSED,
> +                                     char **const groups,
> +                                     void *data ATTRIBUTE_UNUSED)
> +{
> +
> +       pool->def->source.devices[0].geometry.cyliders = atoi(groups[0]);
> +       pool->def->source.devices[0].geometry.heads = atoi(groups[1]);
> +       pool->def->source.devices[0].geometry.sectors = atoi(groups[2]);
> +
> +       return 0;
> +}
> +
> +static int
> +virStorageBackendDiskReadGeometry(virConnectPtr conn, virStoragePoolObjPtr pool)
> +{
> +    const char *prog[] = {
> +        PARTHELPER, pool->def->source.devices[0].path, "-g", NULL,
> +    };
> +
> +    return virStorageBackendRunProgNul(conn,
> +                                       pool,
> +                                       prog,
> +                                       3,
> +                                       virStorageBackendDiskMakePoolGeometry,
> +                                       NULL);
> +}
>  
>  static int
>  virStorageBackendDiskRefreshPool(virConnectPtr conn,
> @@ -313,6 +342,10 @@ virStorageBackendDiskRefreshPool(virConn
>  
>      virStorageBackendWaitForDevices(conn);
>  
> +    if (virStorageBackendDiskReadGeometry(conn, pool) != 0) {
> +	return -1;
> +    }
> +
>      return virStorageBackendDiskReadPartitions(conn, pool, NULL);
>  }
>  

Was rather hoping parted did this kind of alignment for us, but it seems
not. ACK to this, since it is internal only and we can change it if
a better way turns up in the future.


Daniel
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