Re: [Qemu-devel] [PATCH 1/2] virtio-block: support auto-sensing of block sizes

[Paolo Bonzini <pbonzini@redhat.com>]

Il 15/08/2012 09:44, Jens Freimann ha scritto:
> From: Einar Lueck <elelueck@linux.vnet.ibm.com>
> 
> Virtio-blk does not impose fixed block sizes for access to
> backing devices. This patch introduces support for auto
> lookup of the block sizes of the backing block device. This
> automatic lookup needs to be enabled explicitly. Users may
> do this by specifying (physical|logical)_block_size=0.
> Machine types may do this for their defaults, too.
> To achieve this, a new function blkconf_blocksizes is
> implemented. If physical or logical block size are zero
> a corresponding ioctl tries to find an appropriate value.
> If this does not work, 512 is used. blkconf_blocksizes
> is therefore only called w/in the virtio-blk context.
> For s390-virtio, this patch configures auto lookup as
> default.

I'm a bit worried about changing the default for s390, the other parts
look good.

Paolo

> Signed-off-by: Einar Lueck <elelueck@linux.vnet.ibm.com>
> Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
> ---
>  hw/block-common.c    | 28 ++++++++++++++++++++++++++++
>  hw/block-common.h    | 12 +++++++++---
>  hw/qdev-properties.c |  4 +++-
>  hw/s390-virtio-bus.c |  2 +-
>  hw/virtio-blk.c      |  1 +
>  5 files changed, 42 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/block-common.c b/hw/block-common.c
> index f0196d7..336a891 100644
> --- a/hw/block-common.c
> +++ b/hw/block-common.c
> @@ -10,6 +10,9 @@
>  #include "blockdev.h"
>  #include "hw/block-common.h"
>  #include "qemu-error.h"
> +#ifdef __linux__
> +#include <linux/fs.h>
> +#endif
>  
>  void blkconf_serial(BlockConf *conf, char **serial)
>  {
> @@ -24,6 +27,31 @@ void blkconf_serial(BlockConf *conf, char **serial)
>      }
>  }
>  
> +void blkconf_blocksizes(BlockConf *conf)
> +{
> +#ifdef __linux__
> +    int block_size;
> +
> +    if (!conf->physical_block_size) {
> +        if (bdrv_ioctl(conf->bs, BLKPBSZGET, &block_size) == 0) {
> +           conf->physical_block_size = (uint16_t) block_size;
> +        } else {
> +            conf->physical_block_size = BLOCK_PROPERTY_STD_BLKSIZE;
> +        }
> +    }
> +    if (!conf->logical_block_size) {
> +        if (bdrv_ioctl(conf->bs, BLKSSZGET, &block_size) == 0) {
> +            conf->logical_block_size = (uint16_t) block_size;
> +        } else {
> +            conf->logical_block_size = BLOCK_PROPERTY_STD_BLKSIZE;
> +        }
> +    }
> +#else
> +    conf->physical_block_size = BLOCK_PROPERTY_STD_BLKSIZE;
> +    conf->logical_block_size  = BLOCK_PROPERTY_STD_BLKSIZE;
> +#endif
> +}
> +
>  int blkconf_geometry(BlockConf *conf, int *ptrans,
>                       unsigned cyls_max, unsigned heads_max, unsigned secs_max)
>  {
> diff --git a/hw/block-common.h b/hw/block-common.h
> index bb808f7..d593128 100644
> --- a/hw/block-common.h
> +++ b/hw/block-common.h
> @@ -40,18 +40,23 @@ static inline unsigned int get_physical_block_exp(BlockConf *conf)
>      return exp;
>  }
>  
> -#define DEFINE_BLOCK_PROPERTIES(_state, _conf)                          \
> +#define BLOCK_PROPERTY_STD_BLKSIZE 512
> +#define DEFINE_BLOCK_PROPERTIES_EXTENDED(_state, _conf, _blksize)       \
>      DEFINE_PROP_DRIVE("drive", _state, _conf.bs),                       \
>      DEFINE_PROP_BLOCKSIZE("logical_block_size", _state,                 \
> -                          _conf.logical_block_size, 512),               \
> +                          _conf.logical_block_size, _blksize),          \
>      DEFINE_PROP_BLOCKSIZE("physical_block_size", _state,                \
> -                          _conf.physical_block_size, 512),              \
> +                          _conf.physical_block_size, _blksize),         \
>      DEFINE_PROP_UINT16("min_io_size", _state, _conf.min_io_size, 0),  \
>      DEFINE_PROP_UINT32("opt_io_size", _state, _conf.opt_io_size, 0),    \
>      DEFINE_PROP_INT32("bootindex", _state, _conf.bootindex, -1),        \
>      DEFINE_PROP_UINT32("discard_granularity", _state, \
>                         _conf.discard_granularity, 0)
>  
> +#define DEFINE_BLOCK_PROPERTIES(_state, _conf)                          \
> +    DEFINE_BLOCK_PROPERTIES_EXTENDED(_state, _conf,                     \
> +                                     BLOCK_PROPERTY_STD_BLKSIZE)
> +
>  #define DEFINE_BLOCK_CHS_PROPERTIES(_state, _conf)      \
>      DEFINE_PROP_UINT32("cyls", _state, _conf.cyls, 0),  \
>      DEFINE_PROP_UINT32("heads", _state, _conf.heads, 0), \
> @@ -60,6 +65,7 @@ static inline unsigned int get_physical_block_exp(BlockConf *conf)
>  /* Configuration helpers */
>  
>  void blkconf_serial(BlockConf *conf, char **serial);
> +void blkconf_blocksizes(BlockConf *conf);
>  int blkconf_geometry(BlockConf *conf, int *trans,
>                       unsigned cyls_max, unsigned heads_max, unsigned secs_max);
>  
> diff --git a/hw/qdev-properties.c b/hw/qdev-properties.c
> index 8aca0d4..e99dee4 100644
> --- a/hw/qdev-properties.c
> +++ b/hw/qdev-properties.c
> @@ -904,7 +904,9 @@ static void set_blocksize(Object *obj, Visitor *v, void *opaque,
>          error_propagate(errp, local_err);
>          return;
>      }
> -    if (value < min || value > max) {
> +
> +    /* value == 0 indicates that block size should be sensed later on */
> +    if ((value < min || value > max) && value > 0) {
>          error_set(errp, QERR_PROPERTY_VALUE_OUT_OF_RANGE,
>                    dev->id?:"", name, (int64_t)value, min, max);
>          return;
> diff --git a/hw/s390-virtio-bus.c b/hw/s390-virtio-bus.c
> index a245684..562964e 100644
> --- a/hw/s390-virtio-bus.c
> +++ b/hw/s390-virtio-bus.c
> @@ -401,7 +401,7 @@ static TypeInfo s390_virtio_net = {
>  };
>  
>  static Property s390_virtio_blk_properties[] = {
> -    DEFINE_BLOCK_PROPERTIES(VirtIOS390Device, blk.conf),
> +    DEFINE_BLOCK_PROPERTIES_EXTENDED(VirtIOS390Device, blk.conf, 0),
>      DEFINE_BLOCK_CHS_PROPERTIES(VirtIOS390Device, blk.conf),
>      DEFINE_PROP_STRING("serial", VirtIOS390Device, blk.serial),
>  #ifdef __linux__
> diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
> index fd8fa90..d2d73dc 100644
> --- a/hw/virtio-blk.c
> +++ b/hw/virtio-blk.c
> @@ -625,6 +625,7 @@ VirtIODevice *virtio_blk_init(DeviceState *dev, VirtIOBlkConf *blk)
>      }
>  
>      blkconf_serial(&blk->conf, &blk->serial);
> +    blkconf_blocksizes(&blk->conf);
>      if (blkconf_geometry(&blk->conf, NULL, 65535, 255, 255) < 0) {
>          return NULL;
>      }
>