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From: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
To: Max Reitz <mreitz@redhat.com>, qemu-block@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
	Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
	qemu-devel@nongnu.org
Subject: Re: [PATCH v7 23/47] block/snapshot: Fix fallback
Date: Thu, 16 Jul 2020 00:22:37 +0300	[thread overview]
Message-ID: <4b87c07c-f907-129e-3019-5aec59ec476f@virtuozzo.com> (raw)
In-Reply-To: <20200625152215.941773-24-mreitz@redhat.com>

On 25.06.2020 18:21, Max Reitz wrote:
> If the top node's driver does not provide snapshot functionality and we
> want to fall back to a node down the chain, we need to snapshot all
> non-COW children.  For simplicity's sake, just do not fall back if there

I guess it comes to COW children like BDRV_CHILD_DATA | 
BDRV_CHILD_METADATA  rather than non-COW ones, does it?

Andrey


> is more than one such child.  Furthermore, we really only can fall back
> to bs->file and bs->backing, because bdrv_snapshot_goto() has to modify
> the child link (notably, set it to NULL).
>
> Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>   block/snapshot.c | 104 +++++++++++++++++++++++++++++++++++++----------
>   1 file changed, 83 insertions(+), 21 deletions(-)
>
> diff --git a/block/snapshot.c b/block/snapshot.c
...
> +    /*
> +     * Check that there are no other children that would need to be
> +     * snapshotted.  If there are, it is not safe to fall back to
> +     * *fallback.
> +     */
> +    QLIST_FOREACH(child, &bs->children, next) {
> +        if (child->role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
> +                           BDRV_CHILD_FILTERED) &&
> +            child != *fallback)
> +        {
> +            return NULL;
> +        }
> +    }
> +
> +    return fallback;
> +}

...

Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>



  reply	other threads:[~2020-07-15 21:23 UTC|newest]

Thread overview: 173+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-25 15:21 [PATCH v7 00/47] block: Deal with filters Max Reitz
2020-06-25 15:21 ` [PATCH v7 01/47] block: Add child access functions Max Reitz
2020-07-08 17:22   ` Andrey Shinkevich
2020-07-13  9:06   ` Vladimir Sementsov-Ogievskiy
2020-07-16 14:46     ` Max Reitz
2020-07-28 16:09     ` Christophe de Dinechin
2020-08-07  9:33       ` Vladimir Sementsov-Ogievskiy
2020-07-13  9:57   ` Vladimir Sementsov-Ogievskiy
2020-06-25 15:21 ` [PATCH v7 02/47] block: Add chain helper functions Max Reitz
2020-07-08 17:20   ` Andrey Shinkevich
2020-07-09  8:24     ` Max Reitz
2020-07-09  9:07       ` Andrey Shinkevich
2020-07-13 10:18   ` Vladimir Sementsov-Ogievskiy
2020-07-16 14:50     ` Max Reitz
2020-07-16 15:24       ` Vladimir Sementsov-Ogievskiy
2020-06-25 15:21 ` [PATCH v7 03/47] block: bdrv_cow_child() for bdrv_has_zero_init() Max Reitz
2020-07-08 17:23   ` Andrey Shinkevich
2020-08-07  9:37   ` Vladimir Sementsov-Ogievskiy
2020-06-25 15:21 ` [PATCH v7 04/47] block: bdrv_set_backing_hd() is about bs->backing Max Reitz
2020-07-08 17:24   ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 05/47] block: Include filters when freezing backing chain Max Reitz
2020-07-08 17:25   ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 06/47] block: Drop bdrv_is_encrypted() Max Reitz
2020-07-08 17:41   ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 07/47] block: Add bdrv_supports_compressed_writes() Max Reitz
2020-07-08 17:48   ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 08/47] throttle: Support compressed writes Max Reitz
2020-07-08 17:52   ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 09/47] copy-on-read: " Max Reitz
2020-07-08 17:54   ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 10/47] mirror-top: " Max Reitz
2020-07-08 17:58   ` Andrey Shinkevich
2020-08-18 10:27   ` Kevin Wolf
2020-08-19 15:35     ` Max Reitz
2020-08-19 16:00       ` Kevin Wolf
2020-06-25 15:21 ` [PATCH v7 11/47] backup-top: " Max Reitz
2020-07-08 17:59   ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 12/47] block: Use bdrv_filter_(bs|child) where obvious Max Reitz
2020-07-08 18:24   ` Andrey Shinkevich
2020-07-09  8:59     ` Max Reitz
2020-07-09  9:11       ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 13/47] block: Use CAFs in block status functions Max Reitz
2020-07-08 19:13   ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 14/47] stream: Deal with filters Max Reitz
2020-07-09 14:52   ` Andrey Shinkevich
2020-07-09 15:27     ` Andrey Shinkevich
2020-07-10 15:24     ` Max Reitz
2020-07-10 17:41       ` Andrey Shinkevich
2020-07-16 14:59         ` Max Reitz
2020-08-07 10:29           ` Vladimir Sementsov-Ogievskiy
2020-08-10  8:12             ` Max Reitz
2020-08-10 11:04               ` Vladimir Sementsov-Ogievskiy
2020-08-14 15:18                 ` Andrey Shinkevich
2020-08-18 20:45                 ` Andrey Shinkevich
2020-08-19 12:39                 ` Max Reitz
2020-08-19 13:18                   ` Vladimir Sementsov-Ogievskiy
2020-07-09 15:13   ` Andrey Shinkevich
2020-07-10 15:27     ` Max Reitz
2020-08-18 14:28   ` Kevin Wolf
2020-08-19 14:47     ` Max Reitz
2020-08-19 15:16       ` Kevin Wolf
2020-08-20  8:31         ` Max Reitz
2020-08-20  9:22           ` Max Reitz
2020-08-20 10:49             ` Vladimir Sementsov-Ogievskiy
2020-08-20 11:43               ` Max Reitz
2020-06-25 15:21 ` [PATCH v7 15/47] block: Use CAFs when working with backing chains Max Reitz
2020-07-10 15:28   ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 16/47] block: Use bdrv_cow_child() in bdrv_co_truncate() Max Reitz
2020-07-10 15:54   ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 17/47] block: Re-evaluate backing file handling in reopen Max Reitz
2020-07-10 19:42   ` Andrey Shinkevich
2020-07-16 15:04     ` Max Reitz
2020-06-25 15:21 ` [PATCH v7 18/47] block: Flush all children in generic code Max Reitz
2020-07-14 12:52   ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 19/47] vmdk: Drop vmdk_co_flush() Max Reitz
2020-07-14 14:52   ` Andrey Shinkevich
2020-07-16 15:08     ` Max Reitz
2020-06-25 15:21 ` [PATCH v7 20/47] block: Iterate over children in refresh_limits Max Reitz
2020-07-14 18:37   ` Andrey Shinkevich
2020-07-16 15:14     ` Max Reitz
2020-06-25 15:21 ` [PATCH v7 21/47] block: Use CAFs in bdrv_refresh_filename() Max Reitz
2020-07-15 12:52   ` Andrey Shinkevich
2020-07-15 12:58     ` Andrey Shinkevich
2020-07-16 15:21     ` Max Reitz
2020-06-25 15:21 ` [PATCH v7 22/47] block: Use CAF in bdrv_co_rw_vmstate() Max Reitz
2020-07-15 13:39   ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 23/47] block/snapshot: Fix fallback Max Reitz
2020-07-15 21:22   ` Andrey Shinkevich [this message]
2020-07-15 22:18     ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 24/47] block: Use CAFs for debug breakpoints Max Reitz
2020-07-15 21:43   ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 25/47] block: Def. impl.s for get_allocated_file_size Max Reitz
2020-07-15 22:56   ` Andrey Shinkevich
2020-08-19 10:57   ` Kevin Wolf
2020-08-19 15:53     ` Max Reitz
2020-06-25 15:21 ` [PATCH v7 26/47] block: Improve get_allocated_file_size's default Max Reitz
2020-07-20 15:12   ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 27/47] blkverify: Use bdrv_sum_allocated_file_size() Max Reitz
2020-07-20 15:10   ` Andrey Shinkevich
2020-08-19 10:46   ` Kevin Wolf
2020-08-19 15:50     ` Max Reitz
2020-06-25 15:21 ` [PATCH v7 28/47] block/null: Implement bdrv_get_allocated_file_size Max Reitz
2020-07-20 15:10   ` Andrey Shinkevich
2020-07-24  8:58     ` Max Reitz
2020-07-24  9:49       ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 29/47] blockdev: Use CAF in external_snapshot_prepare() Max Reitz
2020-07-20 16:08   ` Andrey Shinkevich
2020-07-24  9:23     ` Max Reitz
2020-07-24 10:37       ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 30/47] block: Report data child for query-blockstats Max Reitz
2020-07-21 11:48   ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 31/47] block: Use child access functions for QAPI queries Max Reitz
2020-07-21 12:30   ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 32/47] block-copy: Use CAF to find sync=top base Max Reitz
2020-07-21 12:42   ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 33/47] mirror: Deal with filters Max Reitz
2020-07-22 18:31   ` Andrey Shinkevich
2020-07-24  9:49     ` Max Reitz
2020-07-24 10:27       ` Andrey Shinkevich
2020-08-19 16:50   ` Kevin Wolf
2020-08-20 10:28     ` Max Reitz
2020-06-25 15:22 ` [PATCH v7 34/47] backup: " Max Reitz
2020-07-23 15:51   ` Andrey Shinkevich
2020-07-24  9:55     ` Max Reitz
2020-06-25 15:22 ` [PATCH v7 35/47] commit: " Max Reitz
2020-07-23 17:15   ` Andrey Shinkevich
2020-07-24 10:36     ` Andrey Shinkevich
2020-08-19 17:58   ` Kevin Wolf
2020-08-20 11:27     ` Max Reitz
2020-08-20 13:47       ` Kevin Wolf
2020-06-25 15:22 ` [PATCH v7 36/47] nbd: Use CAF when looking for dirty bitmap Max Reitz
2020-07-23 17:21   ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 37/47] qemu-img: Use child access functions Max Reitz
2020-07-24 15:51   ` Andrey Shinkevich
2020-08-21 15:29   ` Kevin Wolf
2020-08-24 12:42     ` Max Reitz
2020-06-25 15:22 ` [PATCH v7 38/47] block: Drop backing_bs() Max Reitz
2020-07-24 15:55   ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 39/47] blockdev: Fix active commit choice Max Reitz
2020-08-21 15:50   ` Kevin Wolf
2020-08-24 13:18     ` Max Reitz
2020-08-24 14:07       ` Kevin Wolf
2020-08-24 14:41         ` Max Reitz
2020-08-24 15:06           ` Kevin Wolf
2020-06-25 15:22 ` [PATCH v7 40/47] block: Inline bdrv_co_block_status_from_*() Max Reitz
2020-07-24 18:00   ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 41/47] block: Leave BDS.backing_file constant Max Reitz
2020-07-27 12:27   ` Andrey Shinkevich
2020-07-28 14:10     ` Max Reitz
2020-08-24 13:14   ` Kevin Wolf
2020-08-24 14:29     ` Max Reitz
2020-06-25 15:22 ` [PATCH v7 42/47] iotests: Test that qcow2's data-file is flushed Max Reitz
2020-07-27 13:28   ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 43/47] iotests: Let complete_and_wait() work with commit Max Reitz
2020-07-27 13:35   ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 44/47] iotests: Add filter commit test cases Max Reitz
2020-07-27 17:45   ` Andrey Shinkevich
2020-07-28 14:00     ` Max Reitz
2020-06-25 15:22 ` [PATCH v7 45/47] iotests: Add filter mirror " Max Reitz
2020-08-02 11:05   ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 46/47] iotests: Add test for commit in sub directory Max Reitz
2020-08-02 12:13   ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 47/47] iotests: Test committing to overridden backing Max Reitz
2020-08-02 11:43   ` Andrey Shinkevich
2020-07-08 17:20 ` [PATCH v7 00/47] block: Deal with filters Andrey Shinkevich
2020-07-08 17:32   ` Eric Blake
2020-07-08 19:46     ` Andrey Shinkevich
2020-07-08 20:37       ` Eric Blake
2020-07-09  8:19         ` Max Reitz
2020-07-08 20:47   ` Eric Blake
2020-07-09  8:20     ` Max Reitz
2020-07-09  9:04       ` Andrey Shinkevich
2020-08-24 15:15 ` Kevin Wolf

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