tree b69b4502f4d658bee21e7642c451eda22e15297a
parent 25349e8250e67e7d126fbf0ad213811b62e7e529
author Kevin Wolf <kwolf@redhat.com> 1557163076 +0200
committer Kevin Wolf <kwolf@redhat.com> 1558364936 +0200

block: Add bdrv_try_set_aio_context()

Eventually, we want to make sure that all parents and all children of a
node are in the same AioContext as the node itself. This means that
changing the AioContext may fail because one of the other involved
parties (e.g. a guest device that was configured with an iothread)
cannot allow switching to a different AioContext.

Introduce a set of functions that allow to first check whether all
involved nodes can switch to a new context and only then do the actual
switch. The check recursively covers children and parents.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>