From 222565f65c3fba6825912c2561de7831e514ef3c Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Thu, 9 Jul 2015 10:56:46 +0100
Subject: [PATCH] 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>
---
block/io.c | 3 ++-
hw/block/virtio-blk.c | 2 +-
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/block/io.c b/block/io.c
index 42050a0598..63e3678036 100644
--- a/block/io.c
+++ b/block/io.c
@@ -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;
}
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index f72d4b6069..51f867b513 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -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);
--
2.30.2