From f0ad5712d5d15ff272b9e107910be4aae468fb3d Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 4 Sep 2013 19:00:32 +0200 Subject: [PATCH] block: return BDRV_BLOCK_ZERO past end of backing file 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 Signed-off-by: Stefan Hajnoczi --- block.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/block.c b/block.c index aa9ec835a7..82bbd6c933 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)) { + ret |= BDRV_BLOCK_ZERO; + } else { + BlockDriverState *bs2 = bs->backing_hd; + int64_t length2 = bdrv_getlength(bs2); + if (length2 >= 0 && sector_num >= (length2 >> BDRV_SECTOR_BITS)) { + ret |= BDRV_BLOCK_ZERO; + } + } } return ret; }