Re: [Qemu-devel] [PATCH 1/2] iscsi: add support for bdrv_co_is_allocated()

[Kevin Wolf]

Am 20.06.2013 um 20:20 hat Peter Lieven geschrieben:
> Signed-off-by: Peter Lieven <address@hidden>
> ---
>  block/iscsi.c |   57 
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 57 insertions(+)
> 
> diff --git a/block/iscsi.c b/block/iscsi.c
> index 0bbf0b1..e6b966d 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -49,6 +49,7 @@ typedef struct IscsiLun {
>      uint64_t num_blocks;
>      int events;
>      QEMUTimer *nop_timer;
> +    uint8_t lbpme;
>  } IscsiLun;
>  
>  typedef struct IscsiAIOCB {
> @@ -800,6 +801,60 @@ iscsi_getlength(BlockDriverState *bs)
>      return len;
>  }
>  
> +static int coroutine_fn iscsi_co_is_allocated(BlockDriverState *bs,
> +                                              int64_t sector_num,
> +                                              int nb_sectors, int *pnum)
> +{
> +    IscsiLun *iscsilun = bs->opaque;
> +    struct scsi_task *task = NULL;
> +    struct scsi_get_lba_status *lbas = NULL;
> +    struct scsi_lba_status_descriptor *lbasd = NULL;
> +    int ret;
> +
> +    *pnum = nb_sectors;
> +
> +    if (iscsilun->lbpme == 0) {
> +        return 1;
> +    }
> +
> +    /* in-flight requests could invalidate the lba status result */
> +    while (iscsi_process_flush(iscsilun)) {
> +        qemu_aio_wait();
> +    }

Note that you're blocking here. The preferred way would be something
involving a yield from the coroutine and a reenter as soon as all
requests are done. Maybe a CoRwLock does what you need?

> +
> +    task = iscsi_get_lba_status_sync(iscsilun->iscsi, iscsilun->lun,
> +                                     sector_qemu2lun(sector_num, iscsilun),
> +                                     8+16);

Spacing around operators (8 + 16)

> +
> +    if (task == NULL || task->status != SCSI_STATUS_GOOD) {
> +        scsi_free_scsi_task(task);
> +        return 1;

Error cases should set *pnum = 0 and return 0.

Kevin