Re: [RFC 2/4] qcow2: add configurations for zoned format extension

[Eric Blake]

On Mon, Jun 05, 2023 at 06:41:06PM +0800, Sam Li wrote:
> To configure the zoned format feature on the qcow2 driver, it
> requires following arguments: the device size, zoned profile,
> zoned model, zone size, zone capacity, number of conventional
> zones, limits on zone resources (max append sectors, max open
> zones, and max_active_zones).
> 
> To create a qcow2 file with zoned format, use command like this:
> $ qemu-img create -f qcow2 test.qcow2 -o size=768M -o
> zone_size=64M -o zone_capacity=64M -o zone_nr_conv=0 -o
> max_append_sectors=512 -o max_open_zones=0 -o max_active_zones=0
>  -o zoned_profile=zbc
> 
> Signed-off-by: Sam Li <faithilikerun@gmail.com>
> ---
>  block/qcow2.c                    | 119 +++++++++++++++++++++++++++++++
>  block/qcow2.h                    |  21 ++++++
>  include/block/block-common.h     |   5 ++
>  include/block/block_int-common.h |   8 +++
>  qapi/block-core.json             |  46 ++++++++----
>  5 files changed, 185 insertions(+), 14 deletions(-)
>
...
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 7f3948360d..b886dab42b 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -73,6 +73,7 @@ typedef struct {
>  #define  QCOW2_EXT_MAGIC_CRYPTO_HEADER 0x0537be77
>  #define  QCOW2_EXT_MAGIC_BITMAPS 0x23852875
>  #define  QCOW2_EXT_MAGIC_DATA_FILE 0x44415441
> +#define  QCOW2_EXT_MAGIC_ZONED_FORMAT 0x7a6264
>  
>  static int coroutine_fn
>  qcow2_co_preadv_compressed(BlockDriverState *bs,
> @@ -210,6 +211,7 @@ qcow2_read_extensions(BlockDriverState *bs, uint64_t 
> start_offset,
>      uint64_t offset;
>      int ret;
>      Qcow2BitmapHeaderExt bitmaps_ext;
> +    Qcow2ZonedHeaderExtension zoned_ext;
>  
>      if (need_update_header != NULL) {
>          *need_update_header = false;
> @@ -431,6 +433,37 @@ qcow2_read_extensions(BlockDriverState *bs, uint64_t 
> start_offset,
>              break;
>          }
>  
> +        case QCOW2_EXT_MAGIC_ZONED_FORMAT:
> +        {

Missing a patch to docs/interop/qcow2.txt that describes the new
header so that other qcow2 implementations can be interoperable with
it.

[unrelated - maybe we should convert that file to .rst someday?]

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org