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Re: [Qemu-devel] [PATCH v3 0/5] block/mirror: Fix (?) target backing BDS
From: |
Fam Zheng |
Subject: |
Re: [Qemu-devel] [PATCH v3 0/5] block/mirror: Fix (?) target backing BDS |
Date: |
Sun, 12 Jun 2016 12:23:38 +0800 |
User-agent: |
Mutt/1.6.1 (2016-04-27) |
On Fri, 06/10 20:57, Max Reitz wrote:
> Issue #1: If the target image does not have a backing BDS before mirror
> completion, qemu tries really hard to give it a backing BDS. If the
> source has a backing BDS, it will actually always "succeed".
> In some cases, the target is not supposed to have a backing BDS, though
> (absolute-paths: because of sync=full; existing: because the target
> image does not have a backing file; blockdev-mirror: because of an
> explicit "backing": ""). Then, this is pretty bad behavior.
>
> This should generally not change the target's visible data, but it still
> is ugly.
>
> Issue #2: Currently the backing chain of the target is basically opened
> using bdrv_open_backing_file() (except for sometimes™). This results in
> multiple BDSs for a single physical file, which is bad. In most use
> cases, this is only temporary, but it still is bad.
>
> If we can reuse the existing backing chain of the source (which is with
> drive-mirror in "absolute-paths" mode), we should just do so.
Looks good overall. I left a few trivial comments/questions in individual
patches.
Reviewed-by: Fam Zheng <address@hidden>
- Re: [Qemu-devel] [PATCH v3 1/5] block: Allow replacement of a BDS by its overlay, (continued)
- [Qemu-devel] [PATCH v3 4/5] iotests: Add test for post-mirror backing chains, Max Reitz, 2016/06/10
- [Qemu-devel] [PATCH v3 3/5] block/null: Implement bdrv_refresh_filename(), Max Reitz, 2016/06/10
- [Qemu-devel] [PATCH v3 5/5] iotests: Add test for oVirt-like storage migration, Max Reitz, 2016/06/10
- [Qemu-devel] [PATCH v3 2/5] block/mirror: Fix target backing BDS, Max Reitz, 2016/06/10
- Re: [Qemu-devel] [PATCH v3 0/5] block/mirror: Fix (?) target backing BDS,
Fam Zheng <=
- Re: [Qemu-devel] [PATCH v3 0/5] block/mirror: Fix (?) target backing BDS, Kevin Wolf, 2016/06/13
- Re: [Qemu-devel] [PATCH v3 0/5] block/mirror: Fix (?) target backing BDS, Max Reitz, 2016/06/14