Re: [Qemu-devel] [2.4 PATCH v3 11/19] qmp: add block-dirty-bitmap-clear

[Max Reitz <mreitz@redhat.com>]

On 2015-03-16 at 17:03, John Snow wrote:
>
>
> On 03/16/2015 04:57 PM, Max Reitz wrote:
>> On 2015-03-13 at 14:30, John Snow wrote:
>>> Add bdrv_clear_dirty_bitmap and a matching QMP command,
>>> qmp_block_dirty_bitmap_clear that enables a user to reset
>>> the bitmap attached to a drive.
>>>
>>> This allows us to reset a bitmap in the event of a full
>>> drive backup.
>>>
>>> Signed-off-by: John Snow <jsnow@redhat.com>
>>> ---
>>>   block.c               |  8 ++++++++
>>>   blockdev.c            | 34 ++++++++++++++++++++++++++++++++++
>>>   include/block/block.h |  1 +
>>>   qapi/block-core.json  | 14 ++++++++++++++
>>>   qmp-commands.hx       | 29 +++++++++++++++++++++++++++++
>>>   5 files changed, 86 insertions(+)
>>>
>>> diff --git a/block.c b/block.c
>>> index d276fdc..a98ff49 100644
>>> --- a/block.c
>>> +++ b/block.c
>>> @@ -62,6 +62,7 @@
>>>   struct BdrvDirtyBitmap {
>>>       HBitmap *bitmap;
>>>       BdrvDirtyBitmap *successor;
>>> +    int64_t size;
>>>       char *name;
>>>       bool disabled;
>>>       QLIST_ENTRY(BdrvDirtyBitmap) list;
>>> @@ -5460,6 +5461,7 @@ BdrvDirtyBitmap
>>> *bdrv_create_dirty_bitmap(BlockDriverState *bs,
>>>       }
>>>       bitmap = g_new0(BdrvDirtyBitmap, 1);
>>>       bitmap->bitmap = hbitmap_alloc(bitmap_size,
>>> ffs(sector_granularity) - 1);
>>> +    bitmap->size = bitmap_size;
>>>       bitmap->name = g_strdup(name);
>>>       bitmap->disabled = false;
>>>       QLIST_INSERT_HEAD(&bs->dirty_bitmaps, bitmap, list);
>>> @@ -5662,6 +5664,12 @@ void bdrv_reset_dirty_bitmap(BlockDriverState
>>> *bs, BdrvDirtyBitmap *bitmap,
>>>       hbitmap_reset(bitmap->bitmap, cur_sector, nr_sectors);
>>>   }
>>> +void bdrv_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap)
>>> +{
>>> +    assert(bdrv_dirty_bitmap_enabled(bitmap));
>>> +    hbitmap_reset(bitmap->bitmap, 0, bitmap->size);
>>> +}
>>> +
>>>   static void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
>>>                              int nr_sectors)
>>>   {
>>> diff --git a/blockdev.c b/blockdev.c
>>> index 361c7a4..cba9f2c 100644
>>> --- a/blockdev.c
>>> +++ b/blockdev.c
>>> @@ -2051,6 +2051,40 @@ void qmp_block_dirty_bitmap_remove(const char
>>> *node, const char *name,
>>>       aio_context_release(aio_context);
>>>   }
>>> +/**
>>> + * Completely clear a bitmap, for the purposes of synchronizing a 
>>> bitmap
>>> + * immediately after a full backup operation.
>>> + */
>>> +void qmp_block_dirty_bitmap_clear(const char *node, const char *name,
>>> +                                  Error **errp)
>>> +{
>>> +    AioContext *aio_context;
>>> +    BdrvDirtyBitmap *bitmap;
>>> +    BlockDriverState *bs;
>>> +
>>> +    bitmap = block_dirty_bitmap_lookup(node, name, &bs, &aio_context,
>>> errp);
>>> +    if (!bitmap || !bs) {
>>
>> Again, you need to release the AIO context here if you're not doing that
>> in block_dirty_bitmap_lookup() already.
>>
>> Max
>>
>
> OK. Inclined to fix that in lookup() as I should've to begin with and 
> leave this patch as-is.

With that:

Reviewed-by: Max Reitz <mreitz@redhat.com>

>
> --js
>
>>> +        return;
>>> +    }
>>> +
>>> +    if (bdrv_dirty_bitmap_frozen(bitmap)) {
>>> +        error_setg(errp,
>>> +                   "Bitmap '%s' is currently frozen and cannot be
>>> modified",
>>> +                   name);
>>> +        goto out;
>>> +    } else if (!bdrv_dirty_bitmap_enabled(bitmap)) {
>>> +        error_setg(errp,
>>> +                   "Bitmap '%s' is currently disabled and cannot be
>>> cleared",
>>> +                   name);
>>> +        goto out;
>>> +    }
>>> +
>>> +    bdrv_clear_dirty_bitmap(bitmap);
>>> +
>>> + out:
>>> +    aio_context_release(aio_context);
>>> +}
>>> +
>>>   int hmp_drive_del(Monitor *mon, const QDict *qdict, QObject 
>>> **ret_data)
>>>   {
>>>       const char *id = qdict_get_str(qdict, "id");
>>> diff --git a/include/block/block.h b/include/block/block.h
>>> index 3084b53..10442e0 100644
>>> --- a/include/block/block.h
>>> +++ b/include/block/block.h
>>> @@ -479,6 +479,7 @@ void bdrv_set_dirty_bitmap(BlockDriverState *bs,
>>> BdrvDirtyBitmap *bitmap,
>>>                              int64_t cur_sector, int nr_sectors);
>>>   void bdrv_reset_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap
>>> *bitmap,
>>>                                int64_t cur_sector, int nr_sectors);
>>> +void bdrv_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap);
>>>   void bdrv_dirty_iter_init(BlockDriverState *bs,
>>>                             BdrvDirtyBitmap *bitmap, struct
>>> HBitmapIter *hbi);
>>>   void bdrv_set_dirty_iter(struct HBitmapIter *hbi, int64_t offset);
>>> diff --git a/qapi/block-core.json b/qapi/block-core.json
>>> index f012de2..50970c4 100644
>>> --- a/qapi/block-core.json
>>> +++ b/qapi/block-core.json
>>> @@ -1023,6 +1023,20 @@
>>>     'data': 'BlockDirtyBitmap' }
>>>   ##
>>> +# @block-dirty-bitmap-clear
>>> +#
>>> +# Clear (reset) a dirty bitmap on the device
>>> +#
>>> +# Returns: nothing on success
>>> +#          If @node is not a valid block device, DeviceNotFound
>>> +#          If @name is not found, GenericError with an explanation
>>> +#
>>> +# Since 2.4
>>> +##
>>> +{ 'command': 'block-dirty-bitmap-clear',
>>> +  'data': 'BlockDirtyBitmap' }
>>> +
>>> +##
>>>   # @block_set_io_throttle:
>>>   #
>>>   # Change I/O throttle limits for a block drive.
>>> diff --git a/qmp-commands.hx b/qmp-commands.hx
>>> index 72ac72f..db95e89 100644
>>> --- a/qmp-commands.hx
>>> +++ b/qmp-commands.hx
>>> @@ -1301,6 +1301,35 @@ Example:
>>>   EQMP
>>>       {
>>> +        .name       = "block-dirty-bitmap-clear",
>>> +        .args_type  = "node:B,name:s",
>>> +        .mhandler.cmd_new = 
>>> qmp_marshal_input_block_dirty_bitmap_clear,
>>> +    },
>>> +
>>> +SQMP
>>> +
>>> +block-dirty-bitmap-clear
>>> +------------------------
>>> +Since 2.4
>>> +
>>> +Reset the dirty bitmap associated with a node so that an incremental
>>> backup
>>> +from this point in time forward will only backup clusters modified
>>> after this
>>> +clear operation.
>>> +
>>> +Arguments:
>>> +
>>> +- "node": device/node on which to remove dirty bitmap (json-string)
>>> +- "name": name of the dirty bitmap to remove (json-string)
>>> +
>>> +Example:
>>> +
>>> +-> { "execute": "block-dirty-bitmap-clear", "arguments": { "node":
>>> "drive0",
>>> + "name":
>>> "bitmap0" } }
>>> +<- { "return": {} }
>>> +
>>> +EQMP
>>> +
>>> +    {
>>>           .name       = "blockdev-snapshot-sync",
>>>           .args_type  =
>>> "device:s?,node-name:s?,snapshot-file:s,snapshot-node-name:s?,format:s?,mode:s?", 
>>>
>>>
>>>           .mhandler.cmd_new = qmp_marshal_input_blockdev_snapshot_sync,
>>