Re: [PATCH v3 01/10] block/dirty-bitmap: add recording and busy properties

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23.02.2019 3:06, John Snow wrote:
> The current API allows us to report a single status, which we've defined as:
> 
> Frozen: has a successor, treated as qmp_locked, may or may not be enabled.
> Locked: no successor, qmp_locked. may or may not be enabled.
> Disabled: Not frozen or locked, disabled.
> Active: Not frozen, locked, or disabled.
> 
> The problem is that both "Frozen" and "Locked" mean nearly the same thing,
> and that both of them do not intuit whether they are recording guest writes
> or not.
> 
> This patch deprecates that status field and introduces two orthogonal
> properties instead to replace it.
> 
> Signed-off-by: John Snow <jsnow@xxxxxxxxxx>
> ---
>   block/dirty-bitmap.c       |  9 +++++++++
>   qapi/block-core.json       | 10 +++++++++-
>   qemu-deprecated.texi       |  6 ++++++
>   tests/qemu-iotests/236.out | 28 ++++++++++++++++++++++++++++
>   4 files changed, 52 insertions(+), 1 deletion(-)
> 
> diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
> index c6d4acebfa..101383b3af 100644
> --- a/block/dirty-bitmap.c
> +++ b/block/dirty-bitmap.c
> @@ -226,6 +226,13 @@ DirtyBitmapStatus bdrv_dirty_bitmap_status(BdrvDirtyBitmap *bitmap)
>       }
>   }
>   
> +/* Called with BQL taken.  */
> +static bool bdrv_dirty_bitmap_recording(BdrvDirtyBitmap *bitmap)
> +{
> +    return !bitmap->disabled || (bitmap->successor &&
> +                                 !bitmap->successor->disabled);
> +}
> +
>   /**
>    * Create a successor bitmap destined to replace this bitmap after an operation.
>    * Requires that the bitmap is not frozen and has no successor.
> @@ -448,6 +455,8 @@ BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs)
>           info->has_name = !!bm->name;
>           info->name = g_strdup(bm->name);
>           info->status = bdrv_dirty_bitmap_status(bm);
> +        info->recording = bdrv_dirty_bitmap_recording(bm);
> +        info->busy = bdrv_dirty_bitmap_user_locked(bm);
>           info->persistent = bm->persistent;
>           entry->value = info;
>           *plist = entry;
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 2b8afbb924..6e543594b3 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -458,7 +458,14 @@
>   #
>   # @granularity: granularity of the dirty bitmap in bytes (since 1.4)
>   #
> -# @status: current status of the dirty bitmap (since 2.4)
> +# @status: Deprecated in favor of @recording and @locked. (since 2.4)
> +#
> +# @recording: true if the bitmap is recording new writes from the guest.
> +#             Replaces `active` and `disabled` statuses. (since 4.0)
> +#
> +# @busy: true if the bitmap is in-use by some operation (NBD or jobs)
> +#        and cannot be modified via QMP or used by another operation.
> +#        Replaces `locked` and `frozen` statuses. (since 4.0)


Don't we want instead an array of flags? Which will include also persistent and
inconsistent?


>   #
>   # @persistent: true if the bitmap will eventually be flushed to persistent
>   #              storage (since 4.0)
> @@ -467,6 +474,7 @@
>   ##
>   { 'struct': 'BlockDirtyInfo',
>     'data': {'*name': 'str', 'count': 'int', 'granularity': 'uint32',
> +           'recording': 'bool', 'busy': 'bool',
>              'status': 'DirtyBitmapStatus', 'persistent': 'bool' } }
>   
>   ##
> diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi
> index 45c57952da..4c7ae8180f 100644
> --- a/qemu-deprecated.texi
> +++ b/qemu-deprecated.texi
> @@ -67,6 +67,12 @@ topologies described with -smp include all possible cpus, i.e.
>   "autoload" parameter is now ignored. All bitmaps are automatically loaded
>   from qcow2 images.
>   
> +@subsection query-block result field(s) dirty-bitmaps[i].status (since 4.0)
> +
> +The ``status'' field of the ``BlockDirtyInfo'' structure, returned by
> +the query-block command is deprecated. Two new boolean fields,
> +``recording'' and ``busy'' effectively replace it.
> +
>   @subsection query-cpus (since 2.12.0)
>   
>   The ``query-cpus'' command is replaced by the ``query-cpus-fast'' command.
> diff --git a/tests/qemu-iotests/236.out b/tests/qemu-iotests/236.out
> index 5006f7bca1..815cd053f0 100644
> --- a/tests/qemu-iotests/236.out
> +++ b/tests/qemu-iotests/236.out
> @@ -22,17 +22,21 @@ write -P0xcd 0x3ff0000 64k
>     "bitmaps": {
>       "drive0": [
>         {
> +        "busy": false,
>           "count": 262144,
>           "granularity": 65536,
>           "name": "bitmapB",
>           "persistent": false,
> +        "recording": true,
>           "status": "active"
>         },
>         {
> +        "busy": false,
>           "count": 262144,
>           "granularity": 65536,
>           "name": "bitmapA",
>           "persistent": false,
> +        "recording": true,
>           "status": "active"
>         }
>       ]
> @@ -84,17 +88,21 @@ write -P0xcd 0x3ff0000 64k
>     "bitmaps": {
>       "drive0": [
>         {
> +        "busy": false,
>           "count": 262144,
>           "granularity": 65536,
>           "name": "bitmapB",
>           "persistent": false,
> +        "recording": true,
>           "status": "active"
>         },
>         {
> +        "busy": false,
>           "count": 262144,
>           "granularity": 65536,
>           "name": "bitmapA",
>           "persistent": false,
> +        "recording": true,
>           "status": "active"
>         }
>       ]
> @@ -184,24 +192,30 @@ write -P0xea 0x3fe0000 64k
>     "bitmaps": {
>       "drive0": [
>         {
> +        "busy": false,
>           "count": 393216,
>           "granularity": 65536,
>           "name": "bitmapC",
>           "persistent": false,
> +        "recording": false,
>           "status": "disabled"
>         },
>         {
> +        "busy": false,
>           "count": 262144,
>           "granularity": 65536,
>           "name": "bitmapB",
>           "persistent": false,
> +        "recording": false,
>           "status": "disabled"
>         },
>         {
> +        "busy": false,
>           "count": 458752,
>           "granularity": 65536,
>           "name": "bitmapA",
>           "persistent": false,
> +        "recording": false,
>           "status": "disabled"
>         }
>       ]
> @@ -251,24 +265,30 @@ write -P0xea 0x3fe0000 64k
>     "bitmaps": {
>       "drive0": [
>         {
> +        "busy": false,
>           "count": 393216,
>           "granularity": 65536,
>           "name": "bitmapC",
>           "persistent": false,
> +        "recording": false,
>           "status": "disabled"
>         },
>         {
> +        "busy": false,
>           "count": 262144,
>           "granularity": 65536,
>           "name": "bitmapB",
>           "persistent": false,
> +        "recording": false,
>           "status": "disabled"
>         },
>         {
> +        "busy": false,
>           "count": 458752,
>           "granularity": 65536,
>           "name": "bitmapA",
>           "persistent": false,
> +        "recording": false,
>           "status": "disabled"
>         }
>       ]
> @@ -311,31 +331,39 @@ write -P0xea 0x3fe0000 64k
>     "bitmaps": {
>       "drive0": [
>         {
> +        "busy": false,
>           "count": 458752,
>           "granularity": 65536,
>           "name": "bitmapD",
>           "persistent": false,
> +        "recording": false,
>           "status": "disabled"
>         },
>         {
> +        "busy": false,
>           "count": 393216,
>           "granularity": 65536,
>           "name": "bitmapC",
>           "persistent": false,
> +        "recording": false,
>           "status": "disabled"
>         },
>         {
> +        "busy": false,
>           "count": 262144,
>           "granularity": 65536,
>           "name": "bitmapB",
>           "persistent": false,
> +        "recording": false,
>           "status": "disabled"
>         },
>         {
> +        "busy": false,
>           "count": 458752,
>           "granularity": 65536,
>           "name": "bitmapA",
>           "persistent": false,
> +        "recording": false,
>           "status": "disabled"
>         }
>       ]
> 


-- 
Best regards,
Vladimir

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