Re: [Qemu-block] [PATCH v2 2/2] blockjob: use blk_new_pinned in block_job_create

[Kevin Wolf]

Am 05.06.2019 um 14:32 hat Vladimir Sementsov-Ogievskiy geschrieben:
> child_role job already has .stay_at_node=true, so on bdrv_replace_node
> operation these child are unchanged. Make block job blk behave in same
> manner, to avoid inconsistent intermediate graph states and workarounds
> like in mirror.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>

This feels dangerous. It does what you want it to do if the only graph
change below the BlockBackend is the one in mirror_exit_common. But the
user could also take a snapshot, or in the future hopefully insert a
filter node, and you would then want the BlockBackend to move.

To be honest, even BdrvChildRole.stay_at_node is a bit of a hack. But at
least it's only used for permissions and not for the actual data flow.

Kevin