block: Give nonzero result to blk_get_max_transfer_length()

Making all callers special-case 0 as unlimited is awkward,
and we DO have a hard maximum of BDRV_REQUEST_MAX_SECTORS given
our current block layer API limits.

In the case of scsi, this means that we now always advertise a
limit to the guest, even in cases where the underlying layers
previously use 0 for no inherent limit beyond the block layer.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Eric Blake 2016-06-23 16:37:12 -06:00 committed by Kevin Wolf
parent efaf4781a9
commit 24ce9a2026
3 changed files with 11 additions and 11 deletions

View file

@ -384,7 +384,7 @@ static int multireq_compare(const void *a, const void *b)
void virtio_blk_submit_multireq(BlockBackend *blk, MultiReqBuffer *mrb)
{
int i = 0, start = 0, num_reqs = 0, niov = 0, nb_sectors = 0;
int max_xfer_len = 0;
int max_xfer_len;
int64_t sector_num = 0;
if (mrb->num_reqs == 1) {
@ -394,7 +394,6 @@ void virtio_blk_submit_multireq(BlockBackend *blk, MultiReqBuffer *mrb)
}
max_xfer_len = blk_get_max_transfer_length(mrb->reqs[0]->dev->blk);
max_xfer_len = MIN_NON_ZERO(max_xfer_len, BDRV_REQUEST_MAX_SECTORS);
qsort(mrb->reqs, mrb->num_reqs, sizeof(*mrb->reqs),
&multireq_compare);