Commit 8cbf74b2 authored by Eric Blake's avatar Eric Blake Committed by Kevin Wolf
Browse files

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: default avatarEric Blake <eblake@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 88e63df2

block/qcow2.c

+3 −9
Original line number Diff line number Diff line
@@ -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;

}