Re: [Nbd] Is NBD_CMD_FLAG_FUA valid during NBD_CMD_FLUSH?
- To: Eric Blake <eblake@...696...>
- Cc: "nbd-general@lists.sourceforge.net" <nbd-general@lists.sourceforge.net>, Wouter Verhelst <w@...112...>, "qemu-devel@...530..." <qemu-devel@...530...>
- Subject: Re: [Nbd] Is NBD_CMD_FLAG_FUA valid during NBD_CMD_FLUSH?
- From: Alex Bligh <alex@...872...>
- Date: Fri, 1 Apr 2016 16:46:58 +0100
- Message-id: <9A6A93DB-1BBC-4F62-B8AD-3D5C6BAC0DFF@...872...>
- In-reply-to: <56FE9469.8000900@...696...>
- References: <56FD7B7E.4060004@...696...> <64B326DA-CDF4-4537-B38A-46E7B57C319C@...872...> <56FD8069.7020101@...696...> <FC6D7B08-B1C0-4ED7-ABD0-FE409C43782C@...872...> <56FD89D0.5050408@...696...> <20160401082715.GB25514@...3...> <56FE82B3.4010205@...696...> <33E7C614-E8C4-48FF-84BE-7F2418C65D22@...872...> <56FE8EF8.3080603@...696...> <BBDA394F-F2D2-49A1-9AA1-4B1401458587@...872...> <97BC88F7-95E9-4ACB-BCA2-43A43ED5519E@...872...> <56FE9469.8000900@...696...>
On 1 Apr 2016, at 16:31, Eric Blake <eblake@...696...> wrote:
> When qemu client is talking to a qemu server, there is no
> incompatibility between the two - all client commands that set FUA are
> sanely handled by the recipient server code. But the same is not true
> if you pair a current qemu client with current nbd.git server, as the
> qemu will unconditionally set FUA on flush, and the server now rejects
> it as an invalid flag (thus making it impossible for qemu to flush). So
> we probably ought to fix qemu client to quit unconditionally sending FUA
> (no change when qemu client talks to qemu server); and at the same time
> out to fix NBD server to silently ignore FUA on flush (fix the breakage
> between the pairing).
+1.
--
Alex Bligh
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