[Qemu-devel] [PATCH v3 7/9] qcow2: qcow2_co_preadv: skip using hd_qiov when possible

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

qemu_iovec_memset has @offset parameter, so using hd_qiov for it is not
needed.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/qcow2.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index e650528af7..d6ef606d89 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1887,18 +1887,13 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset,
             goto fail;
         }
 
-        offset_in_cluster = offset_into_cluster(s, offset);
-
-        qemu_iovec_reset(&hd_qiov);
-        qemu_iovec_concat(&hd_qiov, qiov, bytes_done, cur_bytes);
-
         if (ret == QCOW2_CLUSTER_ZERO_PLAIN ||
             ret == QCOW2_CLUSTER_ZERO_ALLOC ||
             (ret == QCOW2_CLUSTER_UNALLOCATED && !bs->backing))
         {
             /* No sense in releasing the lock */
 
-            qemu_iovec_memset(&hd_qiov, 0, 0, cur_bytes);
+            qemu_iovec_memset(qiov, bytes_done, 0, cur_bytes);
 
             bytes -= cur_bytes;
             offset += cur_bytes;
@@ -1906,6 +1901,11 @@ static coroutine_fn int qcow2_co_preadv(BlockDriverState *bs, uint64_t offset,
             continue;
         }
 
+        offset_in_cluster = offset_into_cluster(s, offset);
+
+        qemu_iovec_reset(&hd_qiov);
+        qemu_iovec_concat(&hd_qiov, qiov, bytes_done, cur_bytes);
+
         qemu_co_mutex_unlock(&s->lock);
 
         switch (ret) {
-- 
2.18.0