Re: [PATCH v2 7/7] block: drop tighten_restrictions

[Max Reitz <mreitz@redhat.com>]

On 06.11.20 13:42, Vladimir Sementsov-Ogievskiy wrote:
> The only users of this thing are:
>   1. bdrv_child_try_set_perm, to ignore failures on loosen restrictions
>   2. assertion in bdrv_replace_child
>   3. assertion in bdrv_inactivate_recurse
> 
> Assertions are not enough reason for overcomplication the permission
> update system. So, look at bdrv_child_try_set_perm.
> 
> We are interested in tighten_restrictions only on failure. But on
> failure this field is not reliable: we may fail in the middle of
> permission update, some nodes are not touched and we don't know should
> their permissions be tighten or not. So, we rely on the fact that if we
> loose restrictions on some node (or BdrvChild), we'll not tighten
> restriction in the whole subtree as part of this update (assertions 2
> and 3 rely on this fact as well). And, if we rely on this fact anyway,
> we can just check it on top, and don't pass additional pointer through
> the whole recursive infrastructure.
> 
> Note also, that further patches will fix real bugs in permission update
> system, so now is good time to simplify it, as a help for further
> refactorings.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>   block.c | 88 +++++++++++----------------------------------------------
>   1 file changed, 17 insertions(+), 71 deletions(-)

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