Re: [Qemu-devel] [PATCH alt 1/7] block: Add status callback to bdrv_amend_options()

["Benoît Canet" <benoit.canet@irqsave.net>]

The Saturday 26 Jul 2014 à 21:22:05 (+0200), Max Reitz wrote :

> Depending on the changed options and the image format,
> bdrv_amend_options() may take a significant amount of time. In these
> cases, a way to be informed about the operation's status is desirable.
> 
> Since the operation is rather complex and may fundamentally change the
> image, implementing it as AIO or a couroutine does not seem feasible. On
> the other hand, implementing it as a block job would be significantly
> more difficult than a simple callback and would not add benefits other
> than progress report to the amending operation, because it should not
> actually be run as a block job at all.
> 
> A callback may not be very pretty, but it's very easy to implement and
> perfectly fits its purpose here.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block.c                   | 5 +++--
>  block/qcow2.c             | 5 ++++-
>  include/block/block.h     | 5 ++++-
>  include/block/block_int.h | 3 ++-
>  qemu-img.c                | 2 +-
>  5 files changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/block.c b/block.c
> index 3e252a2..4c8d4d8 100644
> --- a/block.c
> +++ b/block.c
> @@ -5708,12 +5708,13 @@ void bdrv_add_before_write_notifier(BlockDriverState *bs,
>      notifier_with_return_list_add(&bs->before_write_notifiers, notifier);
>  }
>  
> -int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts)
> +int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts,
> +                       BlockDriverAmendStatusCB *status_cb)
>  {
>      if (!bs->drv->bdrv_amend_options) {
>          return -ENOTSUP;
>      }
> -    return bs->drv->bdrv_amend_options(bs, opts);
> +    return bs->drv->bdrv_amend_options(bs, opts, status_cb);
>  }
>  
>  /* This function will be called by the bdrv_recurse_is_first_non_filter method
> diff --git a/block/qcow2.c b/block/qcow2.c
> index b0faa69..757f890 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -2210,7 +2210,8 @@ static int qcow2_downgrade(BlockDriverState *bs, int target_version)
>      return 0;
>  }
>  
> -static int qcow2_amend_options(BlockDriverState *bs, QemuOpts *opts)
> +static int qcow2_amend_options(BlockDriverState *bs, QemuOpts *opts,
> +                               BlockDriverAmendStatusCB *status_cb)
>  {
>      BDRVQcowState *s = bs->opaque;
>      int old_version = s->qcow_version, new_version = old_version;
> @@ -2223,6 +2224,8 @@ static int qcow2_amend_options(BlockDriverState *bs, QemuOpts *opts)
>      int ret;
>      QemuOptDesc *desc = opts->list->desc;
>  
> +    (void)status_cb;

This look like a temporary hack to please the compiler.
Am I right ? Should be comment this ?

> +
>      while (desc && desc->name) {
>          if (!qemu_opt_find(opts, desc->name)) {
>              /* only change explicitly defined options */
> diff --git a/include/block/block.h b/include/block/block.h
> index 32d3676..f2b1799 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -309,7 +309,10 @@ typedef enum {
>  
>  int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res, BdrvCheckMode fix);
>  
> -int bdrv_amend_options(BlockDriverState *bs_new, QemuOpts *opts);
> +typedef void BlockDriverAmendStatusCB(BlockDriverState *bs, int64_t offset,
> +                                      int64_t total_work_size);
> +int bdrv_amend_options(BlockDriverState *bs_new, QemuOpts *opts,
> +                       BlockDriverAmendStatusCB *status_cb);
>  
>  /* external snapshots */
>  bool bdrv_recurse_is_first_non_filter(BlockDriverState *bs,
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index f6c3bef..5c5798d 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -228,7 +228,8 @@ struct BlockDriver {
>      int (*bdrv_check)(BlockDriverState* bs, BdrvCheckResult *result,
>          BdrvCheckMode fix);
>  
> -    int (*bdrv_amend_options)(BlockDriverState *bs, QemuOpts *opts);
> +    int (*bdrv_amend_options)(BlockDriverState *bs, QemuOpts *opts,
> +                              BlockDriverAmendStatusCB *status_cb);
>  
>      void (*bdrv_debug_event)(BlockDriverState *bs, BlkDebugEvent event);
>  
> diff --git a/qemu-img.c b/qemu-img.c
> index ef74ae4..90d6b79 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -2827,7 +2827,7 @@ static int img_amend(int argc, char **argv)
>          goto out;
>      }
>  
> -    ret = bdrv_amend_options(bs, opts);
> +    ret = bdrv_amend_options(bs, opts, NULL);
>      if (ret < 0) {
>          error_report("Error while amending options: %s", strerror(-ret));
>          goto out;
> -- 
> 2.0.3
> 
>