Re: [PATCH 1/3] block: Activate recursively even for already active nodes

[Max Reitz <mreitz@redhat.com>]

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On 17.12.19 15:59, Kevin Wolf wrote:
> bdrv_invalidate_cache_all() assumes that all nodes in a given subtree
> are either active or inactive when it starts. Therefore, as soon as it
> arrives at an already active node, it stops.
> 
> However, this assumption is wrong. For example, it's possible to take a
> snapshot of an inactive node, which results in an active overlay over an
> inactive backing file. The active overlay is probably also the root node
> of an inactive BlockBackend (blk->disable_perm == true).
> 
> In this case, bdrv_invalidate_cache_all() does not need to do anything
> to activate the overlay node, but it still needs to recurse into the
> children and the parents to make sure that after returning success,
> really everything is activated.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block.c | 50 ++++++++++++++++++++++++--------------------------
>  1 file changed, 24 insertions(+), 26 deletions(-)

Basically the only change is to not skip the whole function when the
node is already active but only the part that actually activates the
node.  blk_root_activate() is a no-op for already-active BBs, so this
looks good to me.

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


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