diff options
Diffstat (limited to 'block/qcow2.c')
| -rw-r--r-- | block/qcow2.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/block/qcow2.c b/block/qcow2.c index b05512718c..b6cb4db8bb 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -3860,8 +3860,20 @@ static bool is_zero(BlockDriverState *bs, int64_t offset, int64_t bytes) if (!bytes) { return true; } - res = bdrv_block_status_above(bs, NULL, offset, bytes, &nr, NULL, NULL); - return res >= 0 && (res & BDRV_BLOCK_ZERO) && nr == bytes; + + /* + * bdrv_block_status_above doesn't merge different types of zeros, for + * example, zeros which come from the region which is unallocated in + * the whole backing chain, and zeros which come because of a short + * backing file. So, we need a loop. + */ + do { + res = bdrv_block_status_above(bs, NULL, offset, bytes, &nr, NULL, NULL); + offset += nr; + bytes -= nr; + } while (res >= 0 && (res & BDRV_BLOCK_ZERO) && nr && bytes); + + return res >= 0 && (res & BDRV_BLOCK_ZERO) && bytes == 0; } static coroutine_fn int qcow2_co_pwrite_zeroes(BlockDriverState *bs, |