hw/ide: drop iov field from IDEDMA

@iov is used only to initialize @qiov. Let's use new
qemu_iovec_init_buf() instead, which simplifies the code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20190218140926.333779-18-vsementsov@virtuozzo.com
Message-Id: <20190218140926.333779-18-vsementsov@virtuozzo.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

hw/ide/atapi.c

@@ -420,9 +420,8 @@ static void ide_atapi_cmd_read_dma_cb(void *opaque, int ret)
         data_offset = 0;
     }
     trace_ide_atapi_cmd_read_dma_cb_aio(s, s->lba, n);
-    s->bus->dma->iov.iov_base = (void *)(s->io_buffer + data_offset);
-    s->bus->dma->iov.iov_len = n * ATAPI_SECTOR_SIZE;
-    qemu_iovec_init_external(&s->bus->dma->qiov, &s->bus->dma->iov, 1);
+    qemu_iovec_init_buf(&s->bus->dma->qiov, s->io_buffer + data_offset,
+                        n * ATAPI_SECTOR_SIZE);
 
     s->bus->dma->aiocb = ide_buffered_readv(s, (int64_t)s->lba << 2,
                                             &s->bus->dma->qiov, n * 4,

include/hw/ide/internal.h

@@ -455,7 +455,6 @@ struct IDEDMAOps {
 
 struct IDEDMA {
     const struct IDEDMAOps *ops;
-    struct iovec iov;
     QEMUIOVector qiov;
     BlockAIOCB *aiocb;
 };