On 2014-11-24 at 10:41, Paolo Bonzini wrote:
On 24/11/2014 09:35, Max Reitz wrote:
But what if the dirty bitmap was enabled before so that this enabling
transaction was supposed to be a no-op?
Maybe it's not a problem: The only case in which the enable/disable
operation will fail is if it cannot find the device or bitmap -- in
which case, the abort operation isn't going to be able to affect
anything either.
Well, it's part of a transaction. As far as I understand it, one groups
several operations in one transaction and if any fails, all are aborted.
Therefore, the "enable the dirty bitmap" operation can trivially succeed
(because it was enabled before), but some different operation may fail,
which then results in invocation of this abort function.
Would it work to do the actual enabling/disabling in the commit
function, since it cannot fail?
Too easy. :-)
This patch could then no longer reuse qmp_block_dirty_bitmap_enable(),
but reimplementing it here should be fine (it's short enough).
Max
