Re: [Qemu-devel] [PATCH v2 00/16] qapi: Allow blockdev-add for NBD

[Max Reitz <mreitz@redhat.com>]

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On 01.03.2016 00:24, Eric Blake wrote:
> On 02/29/2016 04:19 PM, Max Reitz wrote:
>> Turns out NBD is not so simple to do if you do it right. Anyway, this
>> series adds blockdev-add support for NBD clients.
>>
>> Patches 1 and 2 add one less and one more complicated QDict function,
>> respectively, which I needed in later NBD patches: Patch 1 for handling
>> legacy options (move "host" to "address.data.host" etc.) and patch 2
>> because I'd like to use the input visitor for transforming the NBD
>> options into a SocketAddress. Unfortunately, the block layer uses
>> flattened QDicts everywhere, so we'll have to unflatten (erect?) them
>> before we can use that visitor.
> 
> Dan had a patch proposal that called the operation "crumple"; I need to
> review both proposals and see which one I like.
> https://lists.gnu.org/archive/html/qemu-devel/2016-02/msg04618.html

Well, here I go again, not looking at patches on the list...

Looking at the design, I like his idea of having an escape sequence;
also, his qdict_crumple() can return boths lists and dicts where my
qdict_unflatten() only returns dicts (then again, this is what
qdict_flatten() always works on). And his patch doesn't suffer from as
much indentation as mine does.

What I like more about my patch, however, is that I'm reusing
qdict_array_split() and qdict_array_entries(). That is mostly because my
function modifies the given QDict, where Dan's does not.

>>
>> Patch 3 adds a test for qdict_unflatten().
>>
>> Patches 4, 5, 6, and 7 are minor patches with no functional relation to
>> this series, other than later patches will touch the code they touch,
>> too.
>>
>> Patches 8 and 9 prepare the code for the addition of a new option
>> prefix, which is "address.".
>>
>> Patch 10 makes the NBD client accept a SocketAddress under the "address"
>> option (or rather, a flattened SocketAddress QDict with its keys
>> prefixed by "address."). The old options "host", "port", and "path" are
>> supported as legacy options and translated to the respective
>> SocketAddress representation.
>>
>> Patch 11 drops usage of "host", "port", and "path" outside of
>> nbd_has_filename_options_conflict(),
>> nbd_process_legacy_socket_options(), and nbd_refresh_filename(), making
>> those options nothing but legacy.
>>
>> Patch 12, the goal of this series, is again not very complicated.
>>
>> Patches 13, 14, and 15 are required for the iotest added in patch 16. It
>> will invoke qemu-nbd, so patch 13 is required. Besides qemu-nbd, it will
>> launch an NBD server VM concurrently to the client VM, which is why
>> patch 14 is required. And finally, it will test whether we can add an
>> NBD BDS by passing it a file descriptor, which patch 15 is needed for
>> (so we use the socket_scm_helper to pass sockets to qemu).
>>
>> Patch 16 then adds the iotest for NBD's blockdev-add interface.
>>
>>
>> Note on the relation to v1: As you can see, most of this series is
>> completely new. Patch 5 was patch 1 in v1, and the only thing that has
>> changed is that I removed the full stop at the end of the error message;
>> consequently I kept Eric's R-b.
> 
> Looks like my review queue is getting longer because I (like several
> other people) are trying to post last-minute series before soft freeze.

So is mine. :-)

Yes, during the last week I had to prioritize patches over reviewing.

Max


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