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Re: [Qemu-devel] [Qemu-block] [PATCH for-4.0] qemu-img: Gracefully shutd
From: |
John Snow |
Subject: |
Re: [Qemu-devel] [Qemu-block] [PATCH for-4.0] qemu-img: Gracefully shutdown when map can't finish |
Date: |
Wed, 27 Mar 2019 16:43:44 -0400 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 |
On 3/26/19 2:40 PM, Eric Blake wrote:
> Trying 'qemu-img map -f raw nbd://localhost:10809' causes the
> NBD server to output a scary message:
>
> qemu-nbd: Disconnect client, due to: Failed to read request: Unexpected
> end-of-file before all bytes were read
>
> This is because the NBD client, being remote, has no way to expose a
> human-readable map (the --output=json data is fine, however). But
> because we exit(1) right after the message, causing the client to
> bypass all block cleanup, the server sees the abrupt exit and warns,
> whereas it would be silent had the client had a chance to send
> NBD_CMD_DISC. Other protocols may have similar cleanup issues, where
> failure to blk_unref() could cause unintended effects.
>
> Signed-off-by: Eric Blake <address@hidden>
Seems good; taking it through the NBD tree helps me keep track of them :)
Reviewed-by: John Snow <address@hidden>