From: Zhengui li <lizhengui@huawei.com>

Concurrent IO becomes serial IO because of the qemu Coroutine lock,
which reduce IO performance severely.

So unlock Coroutine lock before bdrv_co_pwritev and
bdrv_co_preadv to fix it.

Signed-off-by: Zhengui li <lizhengui@huawei.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/vpc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/block/vpc.c b/block/vpc.c
index a902a4c54d..0c279b87c8 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -639,8 +639,10 @@ vpc_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
             qemu_iovec_reset(&local_qiov);
             qemu_iovec_concat(&local_qiov, qiov, bytes_done, n_bytes);
 
+            qemu_co_mutex_unlock(&s->lock);
             ret = bdrv_co_preadv(bs->file, image_offset, n_bytes,
                                  &local_qiov, 0);
+            qemu_co_mutex_lock(&s->lock);
             if (ret < 0) {
                 goto fail;
             }
@@ -697,8 +699,10 @@ vpc_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
         qemu_iovec_reset(&local_qiov);
         qemu_iovec_concat(&local_qiov, qiov, bytes_done, n_bytes);
 
+        qemu_co_mutex_unlock(&s->lock);
         ret = bdrv_co_pwritev(bs->file, image_offset, n_bytes,
                               &local_qiov, 0);
+        qemu_co_mutex_lock(&s->lock);
         if (ret < 0) {
             goto fail;
         }
-- 
2.20.1