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Re: [PATCH 01/22] blockdev: Allow external snapshots everywhere
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From: |
Vladimir Sementsov-Ogievskiy |
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Subject: |
Re: [PATCH 01/22] blockdev: Allow external snapshots everywhere |
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Date: |
Wed, 25 Sep 2019 11:45:24 +0000 |
20.09.2019 18:27, Max Reitz wrote:
> There is no good reason why we would allow external snapshots only on
> the first non-filter node in a chain. Parent BDSs should not care
> whether their child is replaced by a snapshot. (If they do care, they
> should announce that via freezing the chain, which is checked in
> bdrv_append() through bdrv_set_backing_hd().)
>
> Before we had bdrv_is_first_non_filter() here (since 212a5a8f095), there
> was a special function bdrv_check_ext_snapshot() that allowed snapshots
> by default, but block drivers could override this. Only blkverify did
> so, however.
>
> It is not clear to me why blkverify would do so; maybe just so that the
> testee block driver would not be replaced. The introducing commit
> f6186f49e2c does not explain why. Maybe because 08b24cfe376 would have
> been the correct solution? (Which adds a .supports_backing check.)
>
> Signed-off-by: Max Reitz<address@hidden>
Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>
--
Best regards,
Vladimir
- [PATCH 00/22] block: Fix check_to_replace_node(), Max Reitz, 2019/09/20
- [PATCH 01/22] blockdev: Allow external snapshots everywhere, Max Reitz, 2019/09/20
- Re: [PATCH 01/22] blockdev: Allow external snapshots everywhere,
Vladimir Sementsov-Ogievskiy <=
- [PATCH 02/22] blockdev: Allow resizing everywhere, Max Reitz, 2019/09/20
- [PATCH 03/22] block: Drop bdrv_is_first_non_filter(), Max Reitz, 2019/09/20
- [PATCH 04/22] iotests: Let 041 use -blockdev for quorum children, Max Reitz, 2019/09/20
- [PATCH 05/22] quorum: Fix child permissions, Max Reitz, 2019/09/20
- [PATCH 07/22] blkverify: Implement .bdrv_recurse_can_replace(), Max Reitz, 2019/09/20