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Re: [Qemu-devel] [RFC PATCH 2/4] block: add live block commit functional
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [RFC PATCH 2/4] block: add live block commit functionality |
Date: |
Tue, 31 Jul 2012 11:51:48 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120717 Thunderbird/14.0 |
On 07/30/2012 11:16 PM, Jeff Cody wrote:
> This adds the live commit coroutine. This iteration focuses on the
> commit only below the active layer, and not the active layer itself.
>
> The behaviour is similar to block streaming; the sectors are walked
> through, and anything that exists above 'base' is committed back down
> into base. At the end, intermediate images are deleted, and the
> chain stiched together. Images are restored to their original open
s/stiched/stitched/
> +
> +enum {
> + /*
> + * Size of data buffer for populating the image file. This should be
> large
> + * enough to process multiple clusters in a single call, so that
> populating
> + * contiguous regions of the image is efficient.
> + */
> + COMMIT_BUFFER_SIZE = 512 * 1024, /* in bytes */
> +};
Paolo's latest round of patches got to the point of making this
configurable for drive-mirror; is that something you should be copying here?
> +++ b/block_int.h
> @@ -342,4 +342,23 @@ void mirror_start(BlockDriverState *bs, BlockDriverState
> *target,
> BlockDriverCompletionFunc *cb,
> void *opaque, Error **errp);
>
> +/**
> + * commit_start:
> + * @bs: Top Block device
> + * @base: Block device that will be written into, and become the new top
> + * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
> + * @on_error: The action to take upon error.
Do we need to distinguish between rerror and werror?
> + * @cb: Completion function for the job.
> + * @opaque: Opaque pointer value passed to @cb.
> + * @orig_base_flags: The original open flags for the base image
> + * @orig_top_flags: The original open flags for the top image
> + * @errp: Error object.
> + *
> + */
> +void commit_start(BlockDriverState *bs, BlockDriverState *base,
> + BlockDriverState *top, int64_t speed,
> + BlockdevOnError on_error, BlockDriverCompletionFunc *cb,
> + void *opaque, int orig_base_flags, int orig_top_flags,
> + Error **errp);
> +
> #endif /* BLOCK_INT_H */
--
Eric Blake address@hidden +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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- [Qemu-devel] [RFC PATCH 0/4] Live block commit, Jeff Cody, 2012/07/31
- [Qemu-devel] [RFC PATCH 1/4] block: add support functions for live commit, to find and delete images., Jeff Cody, 2012/07/31
- [Qemu-devel] [RFC PATCH 3/4] qerror: new errors for live block commit, QERR_TOP_NOT_FOUND, Jeff Cody, 2012/07/31
- [Qemu-devel] [RFC PATCH 4/4] QAPI: add command for live block commit, 'block-commit', Jeff Cody, 2012/07/31
- [Qemu-devel] [RFC PATCH 2/4] block: add live block commit functionality, Jeff Cody, 2012/07/31
- Re: [Qemu-devel] [RFC PATCH 2/4] block: add live block commit functionality,
Eric Blake <=