From: Max Reitz <mreitz@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
qemu-devel@nongnu.org, qemu-block@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v6 22/42] block: Fix bdrv_get_allocated_file_size's fallback
Date: Wed, 11 Sep 2019 09:37:18 +0200 [thread overview]
Message-ID: <f082931e-154f-5393-f5b0-ff82f43eff31@redhat.com> (raw)
In-Reply-To: <20190911065517.GA4907@localhost.localdomain>
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On 11.09.19 08:55, Kevin Wolf wrote:
> Am 11.09.2019 um 08:20 hat Max Reitz geschrieben:
>> On 10.09.19 16:52, Kevin Wolf wrote:
>>> Am 09.08.2019 um 18:13 hat Max Reitz geschrieben:
>>>> If the driver does not implement bdrv_get_allocated_file_size(), we
>>>> should fall back to cumulating the allocated size of all non-COW
>>>> children instead of just bs->file.
>>>>
>>>> Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>>>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>>>
>>> This smells like an overgeneralisation, but if we want to count all vmdk
>>> extents, the qcow2 external data file, etc. it's an improvement anyway.
>>> A driver that has a child that should not be counted must just remember
>>> to implement the callback.
>>>
>>> Let me think of an example... How about quorum, for a change? :-)
>>> Or the second blkverify child.
>>>
>>> Or eventually the block job filter nodes.
>>
>> I actually think it makes sense for all of these nodes to report the sum
>> of all of their children’s allocated sizes.
>
> Hm... Yes, in a way. But not much more than it would make sense to
> report the sum of the sizes of all images in the whole backing chain
> (this is a useful thing to ask for, just maybe not the right thing to
> return for a low-level interface). But I can accept that it's maybe a
> bit more expected for quorum and blkverify than for COW images.
>
> If you include the block job filter nodes, I have to disagree, though.
> If mirror_top_bs (or any other job filter) sits in the middle of the
> source chain, then I certainly don't want to see the target size added
> to it.
Hm, I don’t care much either way. I think it makes complete sense to
add the target size there, but OTOH it’s only temporary while the job
runs, so it may be a bit confusing if it suddenly goes up and then down
again.
But I think this is the special case, so this is what should be handled
in a driver callback.
>> If a quorum node has three children with allocated sizes of 3 MB, 1 MB,
>> and 2 MB, respectively (totally possible if some have explicit zeroes
>> and others don’t; it may also depend on the protocol, the filesystem,
>> etc.), then I think it makes most sense to report indeed 6 MB for the
>> quorum subtree as a whole. What would you report? 3 MB?
>
> Do it's the quorum way: Just vote!
Add an option for it? Average, maximum, median, majority, sum? :-)
> No, you're right, of course. -ENOTSUP is probably the only other thing
> you could do then.
>
>>> Ehm... Maybe I should just take back what I said first. It almost feels
>>> like it would be better if qcow2 and vmdk explicitly used a handler that
>>> counts all children (could still be a generic one in block.c) rather
>>> than having to remember to disable the functionality everywhere where we
>>> don't want to have it.
>>
>> I don’t, because everywhere we don’t want this functionality, we still
>> need to choose a child. This has to be done by the driver anyway.
>
> Well, by default the primary child, which should cover like 90% of the
> drivers?
Hm, yes.
But I still think that the drivers that do not want to count every
single non-COW child are the exception.
Max
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next prev parent reply other threads:[~2019-09-11 7:39 UTC|newest]
Thread overview: 136+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-09 16:13 [Qemu-devel] [PATCH v6 00/42] block: Deal with filters Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 01/42] block: Mark commit and mirror as filter drivers Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 02/42] copy-on-read: Support compressed writes Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 03/42] throttle: " Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 04/42] block: Add child access functions Max Reitz
2019-08-09 16:56 ` Eric Blake
2019-09-04 16:16 ` Kevin Wolf
2019-09-09 7:56 ` Max Reitz
2019-09-09 9:36 ` Kevin Wolf
2019-09-09 14:04 ` Max Reitz
2019-09-09 16:13 ` Kevin Wolf
2019-09-10 9:14 ` Max Reitz
2019-09-10 10:47 ` Kevin Wolf
2019-09-10 11:36 ` Max Reitz
2019-09-10 12:48 ` Kevin Wolf
2019-09-10 12:59 ` Max Reitz
2019-09-10 13:10 ` Kevin Wolf
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 05/42] block: Add chain helper functions Max Reitz
2019-08-09 17:01 ` Eric Blake
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 06/42] qcow2: Implement .bdrv_storage_child() Max Reitz
2019-08-09 17:07 ` Eric Blake
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 07/42] block: *filtered_cow_child() for *has_zero_init() Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 08/42] block: bdrv_set_backing_hd() is about bs->backing Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 09/42] block: Include filters when freezing backing chain Max Reitz
2019-08-10 13:32 ` Vladimir Sementsov-Ogievskiy
2019-08-12 12:56 ` Max Reitz
2019-09-05 13:05 ` Kevin Wolf
2019-09-09 8:02 ` Max Reitz
2019-09-09 9:40 ` Kevin Wolf
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 10/42] block: Drop bdrv_is_encrypted() Max Reitz
2019-08-10 13:42 ` Vladimir Sementsov-Ogievskiy
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 11/42] block: Add bdrv_supports_compressed_writes() Max Reitz
2019-09-05 13:11 ` Kevin Wolf
2019-09-09 8:09 ` Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 12/42] block: Use bdrv_filtered_rw* where obvious Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 13/42] block: Use CAFs in block status functions Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 14/42] block: Use CAFs when working with backing chains Max Reitz
2019-08-10 15:19 ` Vladimir Sementsov-Ogievskiy
2019-09-05 14:05 ` Kevin Wolf
2019-09-09 8:25 ` Max Reitz
2019-09-09 9:55 ` Kevin Wolf
2019-09-09 14:08 ` Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 15/42] block: Re-evaluate backing file handling in reopen Max Reitz
2019-08-10 16:05 ` Vladimir Sementsov-Ogievskiy
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 16/42] block: Flush all children in generic code Max Reitz
2019-08-10 15:36 ` Vladimir Sementsov-Ogievskiy
2019-08-12 12:58 ` Max Reitz
2019-09-05 16:24 ` Kevin Wolf
2019-09-09 8:31 ` Max Reitz
2019-09-09 10:01 ` Kevin Wolf
2019-09-09 14:15 ` Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 17/42] block: Use CAFs in bdrv_refresh_limits() Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 18/42] block: Use CAFs in bdrv_refresh_filename() Max Reitz
2019-08-10 16:22 ` Vladimir Sementsov-Ogievskiy
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 19/42] block: Use CAF in bdrv_co_rw_vmstate() Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 20/42] block/snapshot: Fix fallback Max Reitz
2019-08-10 16:34 ` Vladimir Sementsov-Ogievskiy
2019-08-12 13:06 ` Max Reitz
2019-09-10 11:56 ` Kevin Wolf
2019-09-10 12:04 ` Max Reitz
2019-09-10 12:49 ` Kevin Wolf
2019-09-10 13:06 ` Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 21/42] block: Use CAFs for debug breakpoints Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 22/42] block: Fix bdrv_get_allocated_file_size's fallback Max Reitz
2019-08-10 16:41 ` Vladimir Sementsov-Ogievskiy
2019-08-12 13:09 ` Max Reitz
2019-08-12 17:14 ` Vladimir Sementsov-Ogievskiy
2019-08-12 19:15 ` Max Reitz
2019-09-10 14:52 ` Kevin Wolf
2019-09-11 6:20 ` Max Reitz
2019-09-11 6:55 ` Kevin Wolf
2019-09-11 7:37 ` Max Reitz [this message]
2019-09-11 8:27 ` Kevin Wolf
2019-09-11 10:00 ` Max Reitz
2019-09-11 10:31 ` Kevin Wolf
2019-09-11 11:00 ` Max Reitz
2019-09-12 10:34 ` Kevin Wolf
2019-11-14 13:11 ` Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 23/42] blockdev: Use CAF in external_snapshot_prepare() Max Reitz
2019-09-10 15:02 ` Kevin Wolf
2019-09-11 6:21 ` Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 24/42] block: Use child access functions for QAPI queries Max Reitz
2019-08-10 16:57 ` Vladimir Sementsov-Ogievskiy
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 25/42] mirror: Deal with filters Max Reitz
2019-08-12 11:09 ` Vladimir Sementsov-Ogievskiy
2019-08-12 13:26 ` Max Reitz
2019-08-14 15:17 ` Vladimir Sementsov-Ogievskiy
2019-08-31 9:57 ` Vladimir Sementsov-Ogievskiy
2019-09-02 14:35 ` Max Reitz
2019-09-03 8:32 ` Vladimir Sementsov-Ogievskiy
2019-09-09 7:41 ` Max Reitz
2019-09-13 12:55 ` Kevin Wolf
2019-09-16 10:26 ` Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 26/42] backup: " Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 27/42] commit: " Max Reitz
2019-08-31 10:44 ` Vladimir Sementsov-Ogievskiy
2019-09-02 14:55 ` Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 28/42] stream: " Max Reitz
2019-08-12 11:55 ` Vladimir Sementsov-Ogievskiy
2019-09-13 14:16 ` Kevin Wolf
2019-09-16 9:52 ` Max Reitz
2019-09-16 14:47 ` Kevin Wolf
2019-12-11 12:52 ` Max Reitz
2019-12-11 15:52 ` Kevin Wolf
2019-12-11 16:12 ` Max Reitz
2019-12-11 16:35 ` Kevin Wolf
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 29/42] nbd: Use CAF when looking for dirty bitmap Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 30/42] qemu-img: Use child access functions Max Reitz
2019-08-12 12:14 ` Vladimir Sementsov-Ogievskiy
2019-08-12 13:28 ` Max Reitz
2019-08-14 16:04 ` Vladimir Sementsov-Ogievskiy
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 31/42] block: Drop backing_bs() Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 32/42] block: Make bdrv_get_cumulative_perm() public Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 33/42] blockdev: Fix active commit choice Max Reitz
2019-08-09 16:13 ` [Qemu-devel] [PATCH v6 34/42] block: Inline bdrv_co_block_status_from_*() Max Reitz
2019-08-09 16:14 ` [Qemu-devel] [PATCH v6 35/42] block: Fix check_to_replace_node() Max Reitz
2019-08-15 15:21 ` Vladimir Sementsov-Ogievskiy
2019-08-15 17:01 ` Max Reitz
2019-08-16 11:01 ` Vladimir Sementsov-Ogievskiy
2019-08-16 13:30 ` Max Reitz
2019-08-16 14:24 ` Vladimir Sementsov-Ogievskiy
2019-08-09 16:14 ` [Qemu-devel] [PATCH v6 36/42] iotests: Add tests for mirror @replaces loops Max Reitz
2019-08-09 16:14 ` [Qemu-devel] [PATCH v6 37/42] block: Leave BDS.backing_file constant Max Reitz
2019-08-16 16:16 ` Vladimir Sementsov-Ogievskiy
2019-08-09 16:14 ` [Qemu-devel] [PATCH v6 38/42] iotests: Let complete_and_wait() work with commit Max Reitz
2019-08-23 5:59 ` Vladimir Sementsov-Ogievskiy
2019-08-09 16:14 ` [Qemu-devel] [PATCH v6 39/42] iotests: Add filter commit test cases Max Reitz
2019-08-31 11:41 ` Vladimir Sementsov-Ogievskiy
2019-09-02 15:06 ` Max Reitz
2019-08-31 12:35 ` Vladimir Sementsov-Ogievskiy
2019-09-02 15:09 ` Max Reitz
2019-08-09 16:14 ` [Qemu-devel] [PATCH v6 40/42] iotests: Add filter mirror " Max Reitz
2019-08-31 12:35 ` Vladimir Sementsov-Ogievskiy
2019-08-09 16:14 ` [Qemu-devel] [PATCH v6 41/42] iotests: Add test for commit in sub directory Max Reitz
2019-08-09 16:14 ` [Qemu-devel] [PATCH v6 42/42] iotests: Test committing to overridden backing Max Reitz
2019-09-03 9:18 ` Vladimir Sementsov-Ogievskiy
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