Il 13/09/2013 09:33, Peter Lieven ha scritto:
> On 06.09.2013 17:39, Stefan Hajnoczi wrote:
>> From: Paolo Bonzini <pbonz...@redhat.com>
>>
>> If the sectors are unallocated and we are past the end of the
>> backing file, they will read as zero.
>>
>> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
>> Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
>> ---
>> block.c | 12 ++++++++++--
>> 1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/block.c b/block.c
>> index aa9ec83..82bbd6c 100644
>> --- a/block.c
>> +++ b/block.c
>> @@ -3102,8 +3102,16 @@ static int64_t coroutine_fn
>> bdrv_co_get_block_status(BlockDriverState *bs,
>> return ret;
>> }
>> - if (!(ret & BDRV_BLOCK_DATA) && bdrv_has_zero_init(bs)) {
>> - ret |= BDRV_BLOCK_ZERO;
>> + if (!(ret & BDRV_BLOCK_DATA)) {
>> + if (bdrv_has_zero_init(bs)) {
> this should be bdi->discard_zeroes. bdrv_has_zero_init() does only give
> a valid result
> right after bdrv_create(). i currently working on extending bdi. I can
> send a patch for this
> if you agree.
Yes, please. Right now there is no bdi->discard_zeroes.
>> + ret |= BDRV_BLOCK_ZERO;
>> + } else {
>> + BlockDriverState *bs2 = bs->backing_hd;
>
> this segfaults if there is no backing_hd. found while testing
> get_block_status with iscsi.
>
> paolo, is this the correct fix?
Yes, thanks.
Paolo
> @@ -3110,7 +3157,7 @@ static int64_t coroutine_fn
> bdrv_co_get_block_status(BlockDriverState *bs,
> if (!(ret & BDRV_BLOCK_DATA)) {
> if (bdrv_has_zero_init(bs)) {
> ret |= BDRV_BLOCK_ZERO;
> - } else {
> + } else if (bs->backing_hd) {
> BlockDriverState *bs2 = bs->backing_hd;
> int64_t length2 = bdrv_getlength(bs2);
> if (length2 >= 0 && sector_num >= (length2 >>
> BDRV_SECTOR_BITS)) {
>
>
>> + int64_t length2 = bdrv_getlength(bs2);
>> + if (length2 >= 0 && sector_num >= (length2 >>
>> BDRV_SECTOR_BITS)) {
>> + ret |= BDRV_BLOCK_ZERO;
>> + }
>> + }
>> }
>> return ret;
>> }
>
