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Re: [Qemu-devel] [PATCH v6 for 2.1 06/10] block: extend block-commit to
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH v6 for 2.1 06/10] block: extend block-commit to accept a string for the backing file |
Date: |
Thu, 19 Jun 2014 15:49:54 +0800 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Tue, Jun 17, 2014 at 05:53:54PM -0400, Jeff Cody wrote:
> On some image chains, QEMU may not always be able to resolve the
> filenames properly, when updating the backing file of an image
> after a block commit.
>
> For instance, certain relative pathnames may fail, or drives may
> have been specified originally by file descriptor (e.g. /dev/fd/???),
> or a relative protocol pathname may have been used.
>
> In these instances, QEMU may lack the information to be able to make
> the correct choice, but the user or management layer most likely does
> have that knowledge.
>
> With this extension to the block-commit api, the user is able to change
> the backing file of the overlay image as part of the block-commit
> operation.
>
> This allows the change to be 'safe', in the sense that if the attempt
> to write the overlay image metadata fails, then the block-commit
> operation returns failure, without disrupting the guest.
>
> If the commit top is the active layer, then specifying the backing
> file string will be treated as an error (there is no overlay image
> to modify in that case).
>
> If a backing file string is not specified in the command, the backing
> file string to use is determined in the same manner as it was
> previously.
>
> Reviewed-by: Eric Blake <address@hidden>
> Signed-off-by: Jeff Cody <address@hidden>
> ---
> block.c | 8 ++++++--
> block/commit.c | 9 ++++++---
> blockdev.c | 8 +++++++-
> include/block/block.h | 3 ++-
> include/block/block_int.h | 3 ++-
> qapi/block-core.json | 23 +++++++++++++++++++++--
> qmp-commands.hx | 19 ++++++++++++++++++-
> 7 files changed, 62 insertions(+), 11 deletions(-)
Reviewed-by: Stefan Hajnoczi <address@hidden>
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- [Qemu-devel] [PATCH v6 for 2.1 02/10] block: add helper function to determine if a BDS is in a chain, (continued)
- [Qemu-devel] [PATCH v6 for 2.1 02/10] block: add helper function to determine if a BDS is in a chain, Jeff Cody, 2014/06/17
- [Qemu-devel] [PATCH v6 for 2.1 03/10] block: simplify bdrv_find_base() and bdrv_find_overlay(), Jeff Cody, 2014/06/17
- [Qemu-devel] [PATCH v6 for 2.1 04/10] block: make 'top' argument to block-commit optional, Jeff Cody, 2014/06/17
- [Qemu-devel] [PATCH v6 for 2.1 05/10] block: Accept node-name arguments for block-commit, Jeff Cody, 2014/06/17
- [Qemu-devel] [PATCH v6 for 2.1 06/10] block: extend block-commit to accept a string for the backing file, Jeff Cody, 2014/06/17
- Re: [Qemu-devel] [PATCH v6 for 2.1 06/10] block: extend block-commit to accept a string for the backing file,
Stefan Hajnoczi <=
- [Qemu-devel] [PATCH v6 for 2.1 07/10] block: add ability for block-stream to use node-name, Jeff Cody, 2014/06/17
- [Qemu-devel] [PATCH v6 for 2.1 08/10] block: add backing-file option to block-stream, Jeff Cody, 2014/06/17
- [Qemu-devel] [PATCH v6 for 2.1 09/10] block: Add QMP documentation for block-stream, Jeff Cody, 2014/06/17
- [Qemu-devel] [PATCH v6 for 2.1 10/10] block: add QAPI command to allow live backing file change, Jeff Cody, 2014/06/17