block/iscsi: fix initialization of iTask in iscsi_co_get_block_status

in case of unaligned requests or on a target that does not support
block provisioning we leave iTask uninitialized and check iTask.task
for NULL later.

Fixes: e38bc234Signed-off-by: NPeter Lieven <pl@kamp.de>
Reviewed-by: NEric Blake <eblake@redhat.com>
Message-Id: <1515425247-21730-1-git-send-email-pl@kamp.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

block/iscsi.c

@@ -658,6 +658,8 @@ static int64_t coroutine_fn iscsi_co_get_block_status(BlockDriverState *bs,
     uint64_t lba;
     int64_t ret;
 
+    iscsi_co_init_iscsitask(iscsilun, &iTask);
+
     if (!is_sector_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
         ret = -EINVAL;
         goto out;
@@ -675,7 +677,6 @@ static int64_t coroutine_fn iscsi_co_get_block_status(BlockDriverState *bs,
 
     lba = sector_qemu2lun(sector_num, iscsilun);
 
-    iscsi_co_init_iscsitask(iscsilun, &iTask);
     qemu_mutex_lock(&iscsilun->mutex);
 retry:
     if (iscsi_get_lba_status_task(iscsilun->iscsi, iscsilun->lun,