block/qcow2: use buffer-based io

Signed-off-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/qcow2.c

@@ -4094,7 +4094,6 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
                             uint64_t bytes, QEMUIOVector *qiov)
 {
     BDRVQcow2State *s = bs->opaque;
-    QEMUIOVector hd_qiov;
     int ret;
     ssize_t out_len;
     uint8_t *buf, *out_buf;
@@ -4161,10 +4160,8 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
         goto fail;
     }
 
-    qemu_iovec_init_buf(&hd_qiov, out_buf, out_len);
-
     BLKDBG_EVENT(s->data_file, BLKDBG_WRITE_COMPRESSED);
-    ret = bdrv_co_pwritev(s->data_file, cluster_offset, out_len, &hd_qiov, 0);
+    ret = bdrv_co_pwrite(s->data_file, cluster_offset, out_len, out_buf, 0);
     if (ret < 0) {
         goto fail;
     }
@@ -4187,7 +4184,6 @@ qcow2_co_preadv_compressed(BlockDriverState *bs,
     int ret = 0, csize, nb_csectors;
     uint64_t coffset;
     uint8_t *buf, *out_buf;
-    QEMUIOVector local_qiov;
     int offset_in_cluster = offset_into_cluster(s, offset);
 
     coffset = file_cluster_offset & s->cluster_offset_mask;
@@ -4198,12 +4194,11 @@ qcow2_co_preadv_compressed(BlockDriverState *bs,
     if (!buf) {
         return -ENOMEM;
     }
-    qemu_iovec_init_buf(&local_qiov, buf, csize);
 
     out_buf = qemu_blockalign(bs, s->cluster_size);
 
     BLKDBG_EVENT(bs->file, BLKDBG_READ_COMPRESSED);
-    ret = bdrv_co_preadv(bs->file, coffset, csize, &local_qiov, 0);
+    ret = bdrv_co_pread(bs->file, coffset, csize, buf, 0);
     if (ret < 0) {
         goto fail;
     }