block: replace IOV_MAX with BlockLimits.max_iov

Request merging must not result in a huge request that exceeds the
maximum number of iovec elements.  Use BlockLimits.max_iov instead of
hardcoding IOV_MAX.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2015-07-09 10:56:46 +01:00
parent 648296e067
commit 222565f65c
2 changed files with 3 additions and 2 deletions

View File

@ -1889,7 +1889,8 @@ static int multiwrite_merge(BlockDriverState *bs, BlockRequest *reqs,
merge = 1;
}
if (reqs[outidx].qiov->niov + reqs[i].qiov->niov + 1 > IOV_MAX) {
if (reqs[outidx].qiov->niov + reqs[i].qiov->niov + 1 >
bs->bl.max_iov) {
merge = 0;
}

View File

@ -414,7 +414,7 @@ void virtio_blk_submit_multireq(BlockBackend *blk, MultiReqBuffer *mrb)
* 3. merge would exceed maximum transfer length of backend device
*/
if (sector_num + nb_sectors != req->sector_num ||
niov > IOV_MAX - req->qiov.niov ||
niov > blk_get_max_iov(blk) - req->qiov.niov ||
req->qiov.size / BDRV_SECTOR_SIZE > max_xfer_len ||
nb_sectors > max_xfer_len - req->qiov.size / BDRV_SECTOR_SIZE) {
submit_requests(blk, mrb, start, num_reqs, niov);