Il 22/06/2013 22:58, Peter Lieven ha scritto:
> write zeroes is emulated by unmap if the
> target supports unmapping an unmapped blocks
> read as zero.
I think you should check BDRV_O_UNMAP in bs->open_flags, and not do this
optimization if it is not set.
Paolo
> Signed-off-by: Peter Lieven <p...@kamp.de>
> ---
> block/iscsi.c | 63
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 63 insertions(+)
>
> diff --git a/block/iscsi.c b/block/iscsi.c
> index 98be71e..683692a 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -906,6 +906,68 @@ static int coroutine_fn
> iscsi_co_is_allocated(BlockDriverState *bs,
> return ret;
> }
>
> +static void
> +iscsi_co_write_zeroes_cb(struct iscsi_context *iscsi, int status,
> + void *command_data, void *opaque)
> +{
> + struct IscsiTask *iTask = opaque;
> + struct scsi_task *task = command_data;
> +
> + iTask->complete = 1;
> + iTask->status = 0;
> +
> + if (status != 0) {
> + error_report("iSCSI: Failed to unmap data on iSCSI lun. %s",
> + iscsi_get_error(iscsi));
> + iTask->status = 1;
> + }
> +
> + scsi_free_scsi_task(task);
> +
> + if (iTask->co) {
> + qemu_coroutine_enter(iTask->co, NULL);
> + }
> +}
> +
> +static int
> +coroutine_fn iscsi_co_write_zeroes(BlockDriverState *bs, int64_t sector_num,
> + int nb_sectors)
> +{
> + IscsiLun *iscsilun = bs->opaque;
> + struct IscsiTask iTask;
> + struct unmap_list list[1];
> +
> + if (!iscsilun->lbprz || !iscsilun->lbpu) {
> + /* fall back to writev */
> + return -ENOTSUP;
> + }
> +
> + iTask.iscsilun = iscsilun;
> + iTask.status = 0;
> + iTask.complete = 0;
> + iTask.bs = bs;
> +
> + list[0].lba = sector_qemu2lun(sector_num, iscsilun);
> + list[0].num = nb_sectors * BDRV_SECTOR_SIZE / iscsilun->block_size;
> +
> + if (iscsi_unmap_task(iscsilun->iscsi, iscsilun->lun, 0, 0, &list[0], 1,
> + iscsi_co_write_zeroes_cb, &iTask) == NULL) {
> + return -EIO;
> + }
> +
> + while (!iTask.complete) {
> + iscsi_set_events(iscsilun);
> + iTask.co = qemu_coroutine_self();
> + qemu_coroutine_yield();
> + }
> +
> + if (iTask.status != 0) {
> + return -EIO;
> + }
> +
> + return 0;
> +}
> +
> static int parse_chap(struct iscsi_context *iscsi, const char *target)
> {
> QemuOptsList *list;
> @@ -1417,6 +1479,7 @@ static BlockDriver bdrv_iscsi = {
> .bdrv_truncate = iscsi_truncate,
>
> .bdrv_co_is_allocated = iscsi_co_is_allocated,
> + .bdrv_co_write_zeroes = iscsi_co_write_zeroes,
>
> .bdrv_aio_readv = iscsi_aio_readv,
> .bdrv_aio_writev = iscsi_aio_writev,
>
