Am 24.06.2013 16:34, schrieb Paolo Bonzini:
> 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.
Ok, I will change this. I will also patch iSCSI to return 0 if bdrv_co_discard
is called and the target does not support unmap.
In this case its save to set discard=on for iSCSI.
Peter
>
> 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,
>>
