From: Kevin Wolf <kwolf@redhat.com>
To: Max Reitz <mreitz@redhat.com>
Cc: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
qemu-devel@nongnu.org, qemu-block@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v6 04/42] block: Add child access functions
Date: Tue, 10 Sep 2019 15:10:46 +0200 [thread overview]
Message-ID: <20190910131046.GH4446@localhost.localdomain> (raw)
In-Reply-To: <fa2bf3a5-a440-bc89-1896-87f0802e974d@redhat.com>
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Am 10.09.2019 um 14:59 hat Max Reitz geschrieben:
> On 10.09.19 14:48, Kevin Wolf wrote:
> > Am 10.09.2019 um 13:36 hat Max Reitz geschrieben:
> >> On 10.09.19 12:47, Kevin Wolf wrote:
> >>> Am 10.09.2019 um 11:14 hat Max Reitz geschrieben:
> >>>> Maybe we should stop declaring Quorum a filter and then rename the
> >>>> bdrv_recurse_is_first_non_filter() to, I don’t know,
> >>>> bdrv_recurse_can_be_replaced_by_mirror()?
> >>>
> >>> Why not.
> >>
> >> It feels difficult to do in this series because this is a whole new can
> >> of worms.
> >>
> >> In patch 35, I actually replace the mirror use case by
> >> is_filtered_child(). So it looks to me as if that should not be done,
> >> because I should instead fix bdrv_recurse_is_first_non_filter() (and
> >> rename it), because quorum does allow replacing its children by mirror,
> >> even if it does not act as a filter for them.
> >>
> >> OTOH, there are other users of bdrv_is_first_non_filter(). Those are
> >> qmp_block_resize() and external_snapshot_prepare(), who throw an error
> >> if that returns false.
> >>
> >> I think that’s just wrong. First of all, I don’t even know why we have
> >> that restriction anymore (I can imagine why it used to make sense before
> >> the permission system). qmp_block_resize() should always work as long
> >> as it can get BLK_PERM_RESIZE; and I don’t know why the parents of some
> >> node would care if you take a snapshot of their child.
> >
> > Hm, doesn't it make sense in a way for qmp_block_resize() at least? It
> > means that you can't resize just a filter, but you need to resize the
> > image that actually provides the data for the filter.
>
> Filters generally implement .bdrv_truncate() by passing it through, so
> it should be fine.
Good point.
Then checking bdrv_is_first_non_filter() probably just forbids the only
command that would actually work correctly (resizing the top-level
filter).
Kevin
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next prev parent reply other threads:[~2019-09-10 13:12 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 [this message]
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
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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