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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
1 changed files with 3 additions and 9 deletions
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12
block/qcow2.c
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@ -2976,22 +2976,16 @@ static bool is_zero(BlockDriverState *bs, int64_t offset, int64_t bytes)
{
int64_t nr;
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 */
if (start + bytes > bs->total_sectors * BDRV_SECTOR_SIZE) {
bytes = bs->total_sectors * BDRV_SECTOR_SIZE - start;
if (offset + bytes > bs->total_sectors * BDRV_SECTOR_SIZE) {
bytes = bs->total_sectors * BDRV_SECTOR_SIZE - offset;
}
if (!bytes) {
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;
}