Am 27.06.2013 um 15:11 hat Peter Lieven geschrieben:
> this patch adds a coroutine for .bdrv_co_is_allocated as well as
> a generic framework that can be used to build coroutines in block/iscsi.
>
> Signed-off-by: Peter Lieven <p...@kamp.de>
> ---
> block/iscsi.c | 123
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 123 insertions(+)
>
> diff --git a/block/iscsi.c b/block/iscsi.c
> index 2e2455d..d31ee95 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -58,6 +58,15 @@ typedef struct IscsiLun {
> uint32_t max_unmap_bdc;
> } IscsiLun;
>
> +typedef struct IscsiTask {
> + int status;
> + int complete;
> + int retries;
> + int do_retry;
> + struct scsi_task *task;
> + Coroutine *co;
> +} IscsiTask;
> +
> typedef struct IscsiAIOCB {
> BlockDriverAIOCB common;
> QEMUIOVector *qiov;
> @@ -113,6 +122,45 @@ iscsi_schedule_bh(IscsiAIOCB *acb)
> qemu_bh_schedule(acb->bh);
> }
>
> +static void
> +iscsi_co_generic_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 = status;
> + iTask->do_retry = 0;
> + iTask->task = task;
> +
> + if (iTask->retries-- > 0 && status == SCSI_STATUS_CHECK_CONDITION
> + && task->sense.key == SCSI_SENSE_UNIT_ATTENTION) {
> + iTask->do_retry = 1;
> + goto out;
> + }
> +
> + if (status != SCSI_STATUS_GOOD) {
> + error_report("iSCSI: Failure. %s", iscsi_get_error(iscsi));
> + goto out;
> + }
> +
> +out:
> + if (iTask->status != SCSI_STATUS_GOOD) {
> + scsi_free_scsi_task(iTask->task);
> + iTask->task = NULL;
> + }
> + if (iTask->co) {
> + qemu_coroutine_enter(iTask->co, NULL);
> + }
> +}
In which context does this callback run? If this is from a separate
thread, you may not do all of this (without even holding the QBL). You
should probably use a BH to switch to the I/O thread.
> +
> +static void iscsi_co_init_iscsitask(IscsiLun *iscsilun, struct IscsiTask
> *iTask)
> +{
> + memset(iTask, 0x00, sizeof(struct IscsiTask));
> + iTask->co = qemu_coroutine_self();
> + iTask->retries = ISCSI_CMD_RETRIES;
> +}
Matter of taste, but in my own code I prefer not to have a memset:
*iTask = (struct IscsiTask) {
.co = qemu_coroutine_self(),
.retries = ISCSI_CMD_RETRIES,
};
> static void
> iscsi_abort_task_cb(struct iscsi_context *iscsi, int status, void
> *command_data,
> @@ -807,6 +855,79 @@ 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_get_lba_status *lbas = NULL;
> + struct scsi_lba_status_descriptor *lbasd = NULL;
> + struct IscsiTask iTask;
> + int ret;
> +
> + /* LUN does not support logical block provisioning */
> + if (iscsilun->lbpme == 0) {
> + *pnum = nb_sectors;
> + return 1;
> + }
> +
> + iscsi_co_init_iscsitask(iscsilun, &iTask);
> +
> +retry:
> + if (iscsi_get_lba_status_task(iscsilun->iscsi, iscsilun->lun,
> + sector_qemu2lun(sector_num, iscsilun),
> + 8 + 16, iscsi_co_generic_cb,
> + &iTask) == NULL) {
> + goto fail;
> + }
> +
> + while (!iTask.complete) {
> + iscsi_set_events(iscsilun);
> + qemu_coroutine_yield();
> + }
> +
> + if (iTask.do_retry) {
> + goto retry;
> + }
> +
> + if (iTask.status != SCSI_STATUS_GOOD) {
> + /* in case the get_lba_status_callout fails (i.e.
> + * because the device is busy or the cmd is not
> + * supported) we pretend all blocks are allocated
> + * for backwards compatiblity */
> + *pnum = nb_sectors;
> + return 1;
> + }
> +
> + lbas = scsi_datain_unmarshall(iTask.task);
> + if (lbas == NULL) {
> + goto fail;
> + }
> +
> + lbasd = &lbas->descriptors[0];
> +
> + if (sector_qemu2lun(sector_num, iscsilun) != lbasd->lba) {
> + goto fail;
> + }
> +
> + *pnum = lbasd->num_blocks * (iscsilun->block_size / BDRV_SECTOR_SIZE);
> + if (*pnum > nb_sectors) {
> + *pnum = nb_sectors;
> + }
> +
> + ret = lbasd->provisioning == SCSI_PROVISIONING_TYPE_MAPPED ? 1 : 0;
Wouldn't it be safer to default to allocated, in case new values are
added in a later protocol version? I agree with returning 0 for both
unmapped and anchored, though.
> + scsi_free_scsi_task(iTask.task);
> + return ret;
> +
> +fail:
> + if (iTask.task != NULL) {
> + scsi_free_scsi_task(iTask.task);
> + }
> + *pnum = 0;
> + return 0;
> +}
Kevin
