static int coroutine_fn iscsi_co_readv(BlockDriverState *bs,

                                       int64_t sector_num, int nb_sectors,

                                       QEMUIOVector *iov)

{

    IscsiLun *iscsilun = bs->opaque;

    struct IscsiTask iTask;

    uint64_t lba;

    uint32_t num_sectors;



    if (!is_sector_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {

        return -EINVAL;

    }



    if (bs->bl.max_transfer &&

        nb_sectors << BDRV_SECTOR_BITS > bs->bl.max_transfer) {

        error_report("iSCSI Error: Read of %d sectors exceeds max_xfer_len "

                     "of %" PRIu32 " bytes", nb_sectors, bs->bl.max_transfer);

        return -EINVAL;

    }



    if (iscsilun->lbprz && nb_sectors >= ISCSI_CHECKALLOC_THRES &&

        !iscsi_allocationmap_is_allocated(iscsilun, sector_num, nb_sectors)) {

        int64_t ret;

        int pnum;

        BlockDriverState *file;

        ret = iscsi_co_get_block_status(bs, sector_num,

                                        BDRV_REQUEST_MAX_SECTORS, &pnum, &file);

        if (ret < 0) {

            return ret;

        }

        if (ret & BDRV_BLOCK_ZERO && pnum >= nb_sectors) {

            qemu_iovec_memset(iov, 0, 0x00, iov->size);

            return 0;

        }

    }



    lba = sector_qemu2lun(sector_num, iscsilun);

    num_sectors = sector_qemu2lun(nb_sectors, iscsilun);



    iscsi_co_init_iscsitask(iscsilun, &iTask);

retry:

    if (iscsilun->use_16_for_rw) {

        iTask.task = iscsi_read16_task(iscsilun->iscsi, iscsilun->lun, lba,

                                       num_sectors * iscsilun->block_size,

                                       iscsilun->block_size, 0, 0, 0, 0, 0,

                                       iscsi_co_generic_cb, &iTask);

    } else {

        iTask.task = iscsi_read10_task(iscsilun->iscsi, iscsilun->lun, lba,

                                       num_sectors * iscsilun->block_size,

                                       iscsilun->block_size,

                                       0, 0, 0, 0, 0,

                                       iscsi_co_generic_cb, &iTask);

    }

    if (iTask.task == NULL) {

        return -ENOMEM;

    }

    scsi_task_set_iov_in(iTask.task, (struct scsi_iovec *) iov->iov, iov->niov);



    while (!iTask.complete) {

        iscsi_set_events(iscsilun);

        qemu_coroutine_yield();

    }



    if (iTask.task != NULL) {

        scsi_free_scsi_task(iTask.task);

        iTask.task = NULL;

    }



    if (iTask.do_retry) {

        iTask.complete = 0;

        goto retry;

    }



    if (iTask.status != SCSI_STATUS_GOOD) {

        return iTask.err_code;

    }



    return 0;

}
