The Saturday 16 Aug 2014 à 20:54:16 (+0200), Max Reitz wrote :
> When falling through to the underlying file in
> bdrv_co_get_block_status(), do not let the number of sectors for which
> information could be obtained be overwritten.
>
> Signed-off-by: Max Reitz <mre...@redhat.com>
> ---
> block.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/block.c b/block.c
> index 3e252a2..c922664 100644
> --- a/block.c
> +++ b/block.c
> @@ -3991,9 +3991,11 @@ static int64_t coroutine_fn
> bdrv_co_get_block_status(BlockDriverState *bs,
> if (bs->file &&
> (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
> (ret & BDRV_BLOCK_OFFSET_VALID)) {
> + int backing_pnum;
> +
> ret2 = bdrv_co_get_block_status(bs->file, ret >> BDRV_SECTOR_BITS,
> - *pnum, pnum);
> - if (ret2 >= 0) {
> + *pnum, &backing_pnum);
> + if (ret2 >= 0 && backing_pnum >= *pnum) {
About backing_pnum >= *pnum.
The documentation of bdrv_co_get_block_status says:
* 'nb_sectors' is the max value 'pnum' should be set to. If nb_sectors goes
* beyond the end of the disk image it will be clamped.
*/
static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
int64_t sector_num,
int nb_sectors, int *pnum)
So clearly after the bdrv_co_get_block_status *pnum >= backing_pnum.
This means that backing_pnum > *pnum will never happen.
I think either this test is wrong or the doc is wrong.
Best regards
Benoît
> /* Ignore errors. This is just providing extra information, it
> * is useful but not necessary.
> */
> --
> 2.0.4
>
>
