block/iscsi: return -ENOMEM if an async call fails immediately

if an async libiscsi call fails directly it can only be due
to an out of memory condition. All other errors are returned
through the callback.
Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/iscsi.c

@@ -308,7 +308,7 @@ retry:
                                     iscsi_co_generic_cb, &iTask);
     if (iTask.task == NULL) {
         g_free(buf);
-        return -EIO;
+        return -ENOMEM;
     }
 #if defined(LIBISCSI_FEATURE_IOVECTOR)
     scsi_task_set_iov_out(iTask.task, (struct scsi_iovec *) iov->iov,
@@ -376,7 +376,7 @@ retry:
         break;
     }
     if (iTask.task == NULL) {
-        return -EIO;
+        return -ENOMEM;
     }
 #if defined(LIBISCSI_FEATURE_IOVECTOR)
     scsi_task_set_iov_in(iTask.task, (struct scsi_iovec *) iov->iov, iov->niov);
@@ -419,7 +419,7 @@ static int coroutine_fn iscsi_co_flush(BlockDriverState *bs)
 retry:
     if (iscsi_synchronizecache10_task(iscsilun->iscsi, iscsilun->lun, 0, 0, 0,
                                       0, iscsi_co_generic_cb, &iTask) == NULL) {
-        return -EIO;
+        return -ENOMEM;
     }
 
     while (!iTask.complete) {
@@ -669,7 +669,7 @@ retry:
                                   sector_qemu2lun(sector_num, iscsilun),
                                   8 + 16, iscsi_co_generic_cb,
                                   &iTask) == NULL) {
-        ret = -EIO;
+        ret = -ENOMEM;
         goto out;
     }
 
@@ -753,7 +753,7 @@ coroutine_fn iscsi_co_discard(BlockDriverState *bs, int64_t sector_num,
 retry:
     if (iscsi_unmap_task(iscsilun->iscsi, iscsilun->lun, 0, 0, &list, 1,
                      iscsi_co_generic_cb, &iTask) == NULL) {
-        return -EIO;
+        return -ENOMEM;
     }
 
     while (!iTask.complete) {
@@ -822,7 +822,7 @@ retry:
                                iscsilun->zeroblock, iscsilun->block_size,
                                nb_blocks, 0, !!(flags & BDRV_REQ_MAY_UNMAP),
                                0, 0, iscsi_co_generic_cb, &iTask) == NULL) {
-        return -EIO;
+        return -ENOMEM;
     }
 
     while (!iTask.complete) {