Re: [Qemu-block] [PATCH v3] block: maintain persistent disabled bitmaps

[Eric Blake]

On 02/02/2018 10:07 AM, Vladimir Sementsov-Ogievskiy wrote:
> To maintain load/store disabled bitmap there is new approach:
> 
>  - deprecate @autoload flag of block-dirty-bitmap-add, make it ignored
>  - store enabled bitmaps as "auto" to qcow2
>  - store disabled bitmaps without "auto" flag to qcow2
>  - on qcow2 open load "auto" bitmaps as enabled and others
>    as disabled (except in_use bitmaps)
> 
> Also, adjust iotests 165 and 176 appropriately.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> ---

> +++ b/qemu-doc.texi
> @@ -2749,6 +2749,13 @@ used and it will be removed with no replacement.
>  The ``convert -s snapshot_id_or_name'' argument is obsoleted
>  by the ``convert -l snapshot_param'' argument instead.
>  
> address@hidden QEMU Machine Protocol (QMP) commands
> +
> address@hidden block-dirty-bitmap-add "autoload" parameter (since 2.12.0)
> +
> +"autoload" parameter is now ignored. All bitmaps are automatically loaded
> +from qcow2 image.

Won't later patches be adding the ability to enable/disable bitmaps,
which then affects whether they are autoloaded?  So we don't forget to
revisit this text in that patch, a better wording might be:

The "autoload" parameter is ignored; all enabled persistent dirty
bitmaps are automatically loaded from a qcow2 image, regardless of the
initial setting requested in this parameter.


> @@ -667,19 +662,6 @@ bool bdrv_has_readonly_bitmaps(BlockDriverState *bs)
>  }
>  
>  /* Called with BQL taken. */
> -void bdrv_dirty_bitmap_set_autoload(BdrvDirtyBitmap *bitmap, bool autoload)
> -{
> -    qemu_mutex_lock(bitmap->mutex);
> -    bitmap->autoload = autoload;
> -    qemu_mutex_unlock(bitmap->mutex);
> -}
> -
> -bool bdrv_dirty_bitmap_get_autoload(const BdrvDirtyBitmap *bitmap)
> -{
> -    return bitmap->autoload;
> -}

Will later patches be reintroducing these functions for learning which
bitmaps are enabled/disabled?  But I'm okay with deleting them in this
patch, even if that is more churn.

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

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