diff options
| -rw-r--r-- | block/cow.c | 36 |
1 files changed, 26 insertions, 10 deletions
diff --git a/block/cow.c b/block/cow.c index f75949607c..dc15e46b6c 100644 --- a/block/cow.c +++ b/block/cow.c @@ -152,18 +152,34 @@ static int coroutine_fn cow_co_is_allocated(BlockDriverState *bs, { int64_t bitnum = sector_num + sizeof(struct cow_header_v2) * 8; uint64_t offset = (bitnum / 8) & -BDRV_SECTOR_SIZE; - uint8_t bitmap[BDRV_SECTOR_SIZE]; - int ret; - int changed; + bool first = true; + int changed = 0, same = 0; - ret = bdrv_pread(bs->file, offset, &bitmap, sizeof(bitmap)); - if (ret < 0) { - return ret; - } + do { + int ret; + uint8_t bitmap[BDRV_SECTOR_SIZE]; + + bitnum &= BITS_PER_BITMAP_SECTOR - 1; + int sector_bits = MIN(nb_sectors, BITS_PER_BITMAP_SECTOR - bitnum); + + ret = bdrv_pread(bs->file, offset, &bitmap, sizeof(bitmap)); + if (ret < 0) { + return ret; + } + + if (first) { + changed = cow_test_bit(bitnum, bitmap); + first = false; + } + + same += cow_find_streak(bitmap, changed, bitnum, nb_sectors); + + bitnum += sector_bits; + nb_sectors -= sector_bits; + offset += BDRV_SECTOR_SIZE; + } while (nb_sectors); - bitnum &= BITS_PER_BITMAP_SECTOR - 1; - changed = cow_test_bit(bitnum, bitmap); - *num_same = cow_find_streak(bitmap, changed, bitnum, nb_sectors); + *num_same = same; return changed; } |