qcow2: Reduce is_zero() rounding

Now that bdrv_is_allocated accepts non-aligned inputs, we can
remove the TODO added in earlier refactoring.

Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Eric Blake 2017-10-11 22:47:19 -05:00 committed by Kevin Wolf
parent 88e63df214
commit 8cbf74b23c

View File

@ -2976,22 +2976,16 @@ static bool is_zero(BlockDriverState *bs, int64_t offset, int64_t bytes)
{ {
int64_t nr; int64_t nr;
int res; int res;
int64_t start;
/* TODO: Widening to sector boundaries should only be needed as
* long as we can't query finer granularity. */
start = QEMU_ALIGN_DOWN(offset, BDRV_SECTOR_SIZE);
bytes = QEMU_ALIGN_UP(offset + bytes, BDRV_SECTOR_SIZE) - start;
/* Clamp to image length, before checking status of underlying sectors */ /* Clamp to image length, before checking status of underlying sectors */
if (start + bytes > bs->total_sectors * BDRV_SECTOR_SIZE) { if (offset + bytes > bs->total_sectors * BDRV_SECTOR_SIZE) {
bytes = bs->total_sectors * BDRV_SECTOR_SIZE - start; bytes = bs->total_sectors * BDRV_SECTOR_SIZE - offset;
} }
if (!bytes) { if (!bytes) {
return true; return true;
} }
res = bdrv_block_status_above(bs, NULL, start, bytes, &nr, NULL, NULL); res = bdrv_block_status_above(bs, NULL, offset, bytes, &nr, NULL, NULL);
return res >= 0 && (res & BDRV_BLOCK_ZERO) && nr == bytes; return res >= 0 && (res & BDRV_BLOCK_ZERO) && nr == bytes;
} }