Am 17.10.2011 17:47, schrieb Stefan Hajnoczi:
> The bdrv_set_copy_on_read() function can be used to programmatically
> enable or disable copy-on-read for a block device. Later patches add
> the actual copy-on-read logic.
>
> Signed-off-by: Stefan Hajnoczi <stefa...@linux.vnet.ibm.com>
> ---
> block.c | 17 +++++++++++++++++
> block.h | 3 +++
> block_int.h | 1 +
> 3 files changed, 21 insertions(+), 0 deletions(-)
>
> diff --git a/block.c b/block.c
> index 2d2c62a..e624ac3 100644
> --- a/block.c
> +++ b/block.c
> @@ -464,6 +464,18 @@ int bdrv_parse_cache_flags(const char *mode, int *flags)
> return 0;
> }
>
> +void bdrv_set_copy_on_read(BlockDriverState *bs, int enable)
bool enable
> +{
> + if (bs->copy_on_read != enable) {
> + if (enable) {
> + bdrv_start_request_tracking(bs);
> + } else {
> + bdrv_stop_request_tracking(bs);
> + }
> + }
> + bs->copy_on_read = enable;
> +}
> +
> /*
> * Common part for opening disk images and files
> */
> @@ -483,6 +495,11 @@ static int bdrv_open_common(BlockDriverState *bs, const
> char *filename,
> bs->open_flags = flags;
> bs->buffer_alignment = 512;
>
> + bs->copy_on_read = 0;
I think it should rather be reset on close. We can assert() it here.
> + if (flags & BDRV_O_RDWR) {
> + bdrv_set_copy_on_read(bs, !!(flags & BDRV_O_COPY_ON_READ));
> + }
> +
> pstrcpy(bs->filename, sizeof(bs->filename), filename);
>
> if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv)) {
> diff --git a/block.h b/block.h
> index e77988e..cb9832c 100644
> --- a/block.h
> +++ b/block.h
> @@ -61,6 +61,7 @@ typedef struct BlockDevOps {
> #define BDRV_O_NATIVE_AIO 0x0080 /* use native AIO instead of the thread
> pool */
> #define BDRV_O_NO_BACKING 0x0100 /* don't open the backing file */
> #define BDRV_O_NO_FLUSH 0x0200 /* disable flushing on this disk */
> +#define BDRV_O_COPY_ON_READ 0x0400 /* copy read backing sectors into image */
>
> #define BDRV_O_CACHE_MASK (BDRV_O_NOCACHE | BDRV_O_CACHE_WB |
> BDRV_O_NO_FLUSH)
>
> @@ -291,6 +292,8 @@ void bdrv_reset_dirty(BlockDriverState *bs, int64_t
> cur_sector,
> int nr_sectors);
> int64_t bdrv_get_dirty_count(BlockDriverState *bs);
>
> +void bdrv_set_copy_on_read(BlockDriverState *bs, int enable);
> +
> void bdrv_set_in_use(BlockDriverState *bs, int in_use);
> int bdrv_in_use(BlockDriverState *bs);
>
> diff --git a/block_int.h b/block_int.h
> index 87ce8b4..8eb4795 100644
> --- a/block_int.h
> +++ b/block_int.h
> @@ -160,6 +160,7 @@ struct BlockDriverState {
> int encrypted; /* if true, the media is encrypted */
> int valid_key; /* if true, a valid encryption key has been set */
> int sg; /* if true, the device is a /dev/sg* */
> + int copy_on_read; /* if true, copy read backing sectors into image */
bool.
Kevin
