Re: [Qemu-devel] [PATCH for-2.10 v3] block: Skip implicit nodes in query-block/blockstats

[Peter Krempa]

On Thu, Jul 20, 2017 at 15:11:54 +0200, Kevin Wolf wrote:
> Commits 0db832f and 6cdbceb introduced the automatic insertion of filter
> nodes above the top layer of mirror and commit block jobs. The
> assumption made there was that since libvirt doesn't do node-level
> management of the block layer yet, it shouldn't be affected by added
> nodes.
> 
> This is true as far as commands issued by libvirt are concerned. It only
> uses BlockBackend names to address nodes, so any operations it performs
> still operate on the root of the tree as intended.
> 
> However, the assumption breaks down when you consider query commands,
> which return data for the wrong node now. These commands also return
> information on some child nodes (bs->file and/or bs->backing), which
> libvirt does make use of, and which refer to the wrong nodes, too.
> 
> One of the consequences is that oVirt gets wrong information about the
> image size and stops the VM in response as long as a mirror or commit
> job is running:
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=1470634
> 
> This patch fixes the problem by hiding the implicit nodes created
> automatically by the mirror and commit block jobs in the output of
> query-block and BlockBackend-based query-blockstats as long as the user
> doesn't indicate that they are aware of those nodes by providing a node
> name for them in the QMP command to start the block job.
> 
> The node-based commands query-named-block-nodes and query-blockstats
> with query-nodes=true still show all nodes, including implicit ones.
> This ensures that users that are capable of node-level management can
> still access the full information; users that only know BlockBackends
> won't use these commands.
> 
> Cc: address@hidden
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
> 
> v3:
> - Fixed skipping during the recursion for query-block [Peter]
> - Fixed backing_file_depth
> - More thorough test case for mirror, added one for commit
> 
> v2:
> - Skip implicit nodes not only on the top level, but also during the recursive
>   calls [Peter]
> - Spelling fix in the commit message [Manos]
> 
>  block.c                    | 13 -------------
>  block/commit.c             |  3 +++
>  block/mirror.c             |  3 +++
>  block/qapi.c               | 33 +++++++++++++++++++++++++++------
>  include/block/block.h      |  1 -
>  include/block/block_int.h  |  1 +
>  qapi/block-core.json       |  6 ++++--
>  tests/qemu-iotests/040     | 30 +++++++++++++++++++++++++++++-
>  tests/qemu-iotests/040.out |  4 ++--
>  tests/qemu-iotests/041     | 38 +++++++++++++++++++++++++++++++++++++-
>  tests/qemu-iotests/041.out |  4 ++--
>  11 files changed, 108 insertions(+), 28 deletions(-)

Reviewed-by: Peter Krempa <address@hidden>

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