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Re: [Qemu-devel] [PATCH for-2.7 v2 07/17] rbd: Implement image locking
From: |
Fam Zheng |
Subject: |
Re: [Qemu-devel] [PATCH for-2.7 v2 07/17] rbd: Implement image locking |
Date: |
Mon, 25 Apr 2016 08:42:50 +0800 |
User-agent: |
Mutt/1.6.0 (2016-04-01) |
On Fri, 04/22 21:57, Jason Dillaman wrote:
> Since this cannot automatically recover from a crashed QEMU client with an
> RBD image, perhaps this RBD locking should not default to enabled.
> Additionally, this will conflict with the "exclusive-lock" feature
> available since the Ceph Hammer-release since both utilize the same locking
> construct.
>
> As a quick background, the optional exclusive-lock feature can be
> enabled/disabled on image and safely/automatically handles the case of
> recovery from a crashed client. Under normal conditions, the RBD
> exclusive-lock feature automatically acquires the lock upon the first
> attempt to write to the image and transparently transitions ownership of
> the lock between two or more clients -- used for QEMU live-migration.
Is it enabled by default?
>
> I'd be happy to add a new librbd API method to explicitly expose acquiring
> and releasing the RBD exclusive lock since it certainly solves a couple
> compromises in our current QEMU integration.
Does the API do enable/disable or acquire/relase? Could you explain the
differences between it and rbd_lock_exclusive?
Fam
[Qemu-devel] [PATCH for-2.7 v2 06/17] gluster: Implement .bdrv_lockf, Fam Zheng, 2016/04/14
[Qemu-devel] [PATCH for-2.7 v2 07/17] rbd: Implement image locking, Fam Zheng, 2016/04/14
[Qemu-devel] [PATCH for-2.7 v2 08/17] qemu-io: Add "-L" option for BDRV_O_NO_LOCK, Fam Zheng, 2016/04/14
[Qemu-devel] [PATCH for-2.7 v2 09/17] qemu-img: Add "-L" option to sub commands, Fam Zheng, 2016/04/14