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Re: [Qemu-devel] [RFC PATCH] rbd: Don't convert keypairs to JSON and bac
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [RFC PATCH] rbd: Don't convert keypairs to JSON and back |
Date: |
Mon, 30 Jul 2018 10:20:36 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) |
Jeff Cody <address@hidden> writes:
> On Wed, Jul 25, 2018 at 10:56:48AM -0500, Eric Blake wrote:
>> On 07/25/2018 10:10 AM, Markus Armbruster wrote:
>> >qemu_rbd_parse_filename() builds a keypairs QList, converts it to JSON, and
>> >stores the resulting QString in a QDict.
>> >
>> >qemu_rbd_co_create_opts() and qemu_rbd_open() get the QString from the
>> >QDict, pass it to qemu_rbd_set_keypairs(), which converts it back into
>> >a QList.
>> >
>> >Drop both conversions, store the QList instead.
>> >
>> >This affects output of qemu-img info. Before this patch:
>> >
>> > $ qemu-img info
>> > rbd:rbd/testimg.raw:mon_host=192.168.15.180:rbd_cache=true:conf=/tmp/ceph.conf
>> > [junk printed by Ceph library code...]
>> > image: json:{"driver": "raw", "file": {"pool": "rbd", "image":
>> > "testimg.raw", "conf": "/tmp/ceph.conf", "driver": "rbd",
>> > "=keyvalue-pairs": "[\"mon_host\", \"192.168.15.180\", \"rbd_cache\",
>> > \"true\"]"}}
>> > [more output, not interesting here]
>> >
>> >After this patch, we get
>> >
>> > image: json:{"driver": "raw", "file": {"pool": "rbd", "image":
>> > "testimg.raw", "conf": "/tmp/ceph.conf", "driver": "rbd",
>> > "=keyvalue-pairs": ["mon_host", "192.168.15.180", "rbd_cache", "true"]}}
>> >
>> >The value of member "=keyvalue-pairs" changes from a string containing
>> >a JSON array to that JSON array. That's an improvement of sorts. However:
>> >
>> >* Should "=keyvalue-pairs" even be visible here? It's supposed to be
>> > purely internal...
>>
>> I'd argue that since it is supposed to be internal (as evidenced by the
>> leading '=' that does not name a normal variable), changing it doesn't hurt
>> stability. But yes, it would be nicer if we could filter it entirely so that
>> it does not appear in json: output, if it doesn't truly affect the contents
>> that the guest would see.
>>
>> >
>> >* Is this a stable interface we need to preserve, warts and all?
>>
>> I hope not.
>>
>> >
>> >Signed-off-by: Markus Armbruster <address@hidden>
>> >---
>> > block/rbd.c | 50 ++++++++++++++++++++++----------------------------
>> > 1 file changed, 22 insertions(+), 28 deletions(-)
>>
>> I'm not yet convinced if we want this patch for 3.0 without more comments
>> from the RBD experts, nor do I see too much of an issue if this doesn't go
>> in until 3.1. But as to the code changes itself, I find them nice.
>
> Based on my IRC discussions with Markus, I believe the target for this patch
> is indeed 3.1, not 3.0.
Unless we conclude we want to change qemu-img info sooner rather than
later, which seems unlikely.