On Tue, Jul 05, 2011 at 12:41:20AM -0400, Devin Nakamura wrote:
Please use 'block' instead of 'block_int' as the tag for this patch. I
usually do git log <filename> to find out which tag is used for a
particular file. 'block_int' has never been used in qemu.git but
'block' is used on block layer changes.
> add functions to block driver interface to support inplace image conversion
>
> Signed-off-by: Devin Nakamura <devin...@gmail.com>
> ---
> block_int.h | 10 ++++++++++
> 1 files changed, 10 insertions(+), 0 deletions(-)
>
> diff --git a/block_int.h b/block_int.h
> index 1e265d2..ef311c7 100644
> --- a/block_int.h
> +++ b/block_int.h
> @@ -136,6 +136,16 @@ struct BlockDriver {
> * zeros, 0 otherwise.
> */
> int (*bdrv_has_zero_init)(BlockDriverState *bs);
> +
> + /* Image conversion stuff */
How about:
/* In-place image conversion */
> + int (*bdrv_open_conversion_target)(BlockDriverState *bs, char *filename,
> + QEMUOptionParameter *options);
> + int (*bdrv_get_mapping)(BlockDriverState *bs, uint64_t *guest_offset,
> + uint64_t *host_offset, uint64_t *contiguous_bytes);
> + int (*bdrv_map)(BlockDriverState *bs, uint64_t *guest_offset,
> + uint64_t *host_offset, uint64_t *contiguous_bytes);
> + int (*bdrv_copy_header) (BlockDriverState *bs);
Please document these functions so people working on block drivers know what
semantics they must implement. Unfortunately other interfaces are not
documented but I don't see a reason to avoid documentation in the future.
Important bits would be:
* How is .bdrv_open_conversion_target() different from a regular .bdrv_open()?
* Which BlockDriver functions are fair game to be called while opened as a
conversion target?
* Any constraints or assumptions when a block device is in conversion target
mode?
* How do the pointer arguments of .bdrv_get_mapping() behave? Which arguments
are inputs, outputs, input/output?
* Does .bdrv_copy_header() actually copy any header or does it "install" or
"write out" a new header?
* After .bdrv_copy_header() is the block device upgraded to first-class
operation or do you need to close and then reopen the image file?
Stefan
