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Re: [Qemu-devel] [PATCH] migration: Fix race of image locking between sr
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From: |
Juan Quintela |
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Subject: |
Re: [Qemu-devel] [PATCH] migration: Fix race of image locking between src and dst |
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Date: |
Mon, 19 Jun 2017 17:26:03 +0200 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux) |
Fam Zheng <address@hidden> wrote:
> Previously, dst side will immediately try to lock the write byte upon
> receiving QEMU_VM_EOF, but at src side, bdrv_inactivate_all() is only
> done after sending it. If the src host is under load, dst may fail to
> acquire the lock due to racing with the src unlocking it.
>
> Fix this by hoisting the bdrv_inactivate_all() operation before
> QEMU_VM_EOF.
>
> N.B. A further improvement could possibly be done to cleanly handover
> locks between src and dst, so that there is no window where a third QEMU
> could steal the locks and prevent src and dst from running.
>
> Reported-by: Peter Maydell <address@hidden>
> Signed-off-by: Fam Zheng <address@hidden>
Reviewed-by: Juan Quintela <address@hidden>