14.02.2019 2:23, John Snow wrote:
> Instead of implying a locked status, make it explicit.
locked interferes with bitmap mutex, so may be better "qmp_locked state", but not sure.
> Now, bitmaps in use by migration, NBD or backup operations
> are all treated the same way with the same code paths.
>
> Signed-off-by: John Snow <jsnow@xxxxxxxxxx>
> Reviewed-by: Eric Blake <eblake@xxxxxxxxxx>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@xxxxxxxxxxxxx>
Hmm. Isn't it better to make successor-related staff unrelated to locking at all?
So, backup will call set_qmp_locked like others? And then do create_successor,
abdicate, reclaim, whatever it wants, and finally set_qmp_locked(false) ?
To make it work even more in the same path. But it may be done separately, if we
want.
> ---
> block/dirty-bitmap.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
> index bb2e19e0d8..2042c62602 100644
> --- a/block/dirty-bitmap.c
> +++ b/block/dirty-bitmap.c
> @@ -188,10 +188,8 @@ bool bdrv_dirty_bitmap_has_successor(BdrvDirtyBitmap *bitmap)
> return bitmap->successor;
> }
>
> -/* Both conditions disallow user-modification via QMP. */
> bool bdrv_dirty_bitmap_user_locked(BdrvDirtyBitmap *bitmap) {
> - return bdrv_dirty_bitmap_has_successor(bitmap) ||
> - bdrv_dirty_bitmap_qmp_locked(bitmap);
> + return bdrv_dirty_bitmap_qmp_locked(bitmap);
> }
>
> void bdrv_dirty_bitmap_set_qmp_locked(BdrvDirtyBitmap *bitmap, bool qmp_locked)
> @@ -266,8 +264,9 @@ int bdrv_dirty_bitmap_create_successor(BlockDriverState *bs,
> child->disabled = bitmap->disabled;
> bitmap->disabled = true;
>
> - /* Install the successor and freeze the parent */
> + /* Install the successor and lock the parent */
> bitmap->successor = child;
> + bitmap->qmp_locked = true;
> return 0;
> }
>
> @@ -321,6 +320,7 @@ BdrvDirtyBitmap *bdrv_dirty_bitmap_abdicate(BlockDriverState *bs,
> bitmap->successor = NULL;
> successor->persistent = bitmap->persistent;
> bitmap->persistent = false;
> + bitmap->qmp_locked = false;
> bdrv_release_dirty_bitmap(bs, bitmap);
>
> return successor;
> @@ -349,6 +349,7 @@ BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap_locked(BlockDriverState *bs,
> }
>
> parent->disabled = successor->disabled;
> + parent->qmp_locked = false;
> bdrv_release_dirty_bitmap_locked(successor);
> parent->successor = NULL;
>
>
--
Best regards,
Vladimir
