Re: [Qemu-devel] [PATCH] block/iscsi: introduce bdrv_co_{readv, writev, flush_to_disk}

[Paolo Bonzini]

Il 02/10/2013 17:41, Peter Lieven ha scritto:
> this converts read, write and flush functions from aio to coroutines.

I'm not sure it's already the time for this...  Cancellation sucks in
QEMU, and this is going to make things even worse.

Paolo

> Signed-off-by: Peter Lieven <address@hidden>
> ---
>  block/iscsi.c |  405 
> +++++++++++++++------------------------------------------
>  1 file changed, 107 insertions(+), 298 deletions(-)
> 
> diff --git a/block/iscsi.c b/block/iscsi.c
> index 5c7baee..f37e3c5 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -237,44 +237,6 @@ iscsi_process_write(void *arg)
>      iscsi_set_events(iscsilun);
>  }
>  
> -static int
> -iscsi_aio_writev_acb(IscsiAIOCB *acb);
> -
> -static void
> -iscsi_aio_write16_cb(struct iscsi_context *iscsi, int status,
> -                     void *command_data, void *opaque)
> -{
> -    IscsiAIOCB *acb = opaque;
> -
> -    trace_iscsi_aio_write16_cb(iscsi, status, acb, acb->canceled);
> -
> -    g_free(acb->buf);
> -    acb->buf = NULL;
> -
> -    if (acb->canceled != 0) {
> -        return;
> -    }
> -
> -    acb->status = 0;
> -    if (status != 0) {
> -        if (status == SCSI_STATUS_CHECK_CONDITION
> -            && acb->task->sense.key == SCSI_SENSE_UNIT_ATTENTION
> -            && acb->retries-- > 0) {
> -            scsi_free_scsi_task(acb->task);
> -            acb->task = NULL;
> -            if (iscsi_aio_writev_acb(acb) == 0) {
> -                iscsi_set_events(acb->iscsilun);
> -                return;
> -            }
> -        }
> -        error_report("Failed to write16 data to iSCSI lun. %s",
> -                     iscsi_get_error(iscsi));
> -        acb->status = -EIO;
> -    }
> -
> -    iscsi_schedule_bh(acb);
> -}
> -
>  static int64_t sector_lun2qemu(int64_t sector, IscsiLun *iscsilun)
>  {
>      return sector * iscsilun->block_size / BDRV_SECTOR_SIZE;
> @@ -299,324 +261,172 @@ static bool is_request_lun_aligned(int64_t 
> sector_num, int nb_sectors,
>      return 1;
>  }
>  
> -static int
> -iscsi_aio_writev_acb(IscsiAIOCB *acb)
> +static int coroutine_fn iscsi_co_writev(BlockDriverState *bs,
> +                                        int64_t sector_num, int nb_sectors,
> +                                        QEMUIOVector *iov)
>  {
> -    struct iscsi_context *iscsi = acb->iscsilun->iscsi;
> -    size_t size;
> -    uint32_t num_sectors;
> +    IscsiLun *iscsilun = bs->opaque;
> +    struct IscsiTask iTask;
>      uint64_t lba;
> -#if !defined(LIBISCSI_FEATURE_IOVECTOR)
> -    struct iscsi_data data;
> -#endif
> -    int ret;
> -
> -    acb->canceled   = 0;
> -    acb->bh         = NULL;
> -    acb->status     = -EINPROGRESS;
> -    acb->buf        = NULL;
> +    uint32_t num_sectors;
> +    uint8_t *data = NULL;
> +    uint8_t *buf = NULL;
>  
> -    /* this will allow us to get rid of 'buf' completely */
> -    size = acb->nb_sectors * BDRV_SECTOR_SIZE;
> +    if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
> +        return -EINVAL;
> +    }
>  
> +    lba = sector_qemu2lun(sector_num, iscsilun);
> +    num_sectors = sector_qemu2lun(nb_sectors, iscsilun);
>  #if !defined(LIBISCSI_FEATURE_IOVECTOR)
> -    data.size = MIN(size, acb->qiov->size);
> -
>      /* if the iovec only contains one buffer we can pass it directly */
> -    if (acb->qiov->niov == 1) {
> -        data.data = acb->qiov->iov[0].iov_base;
> +    if (iov->niov == 1) {
> +        data = iov->iov[0].iov_base;
>      } else {
> -        acb->buf = g_malloc(data.size);
> -        qemu_iovec_to_buf(acb->qiov, 0, acb->buf, data.size);
> -        data.data = acb->buf;
> +        size_t size = MIN(nb_sectors * BDRV_SECTOR_SIZE, iov->size);
> +        buf = g_malloc(size);
> +        qemu_iovec_to_buf(iov, 0, buf, size);
> +        data = buf;
>      }
>  #endif
> -
> -    acb->task = malloc(sizeof(struct scsi_task));
> -    if (acb->task == NULL) {
> -        error_report("iSCSI: Failed to allocate task for scsi WRITE16 "
> -                     "command. %s", iscsi_get_error(iscsi));
> -        return -1;
> +    iscsi_co_init_iscsitask(iscsilun, &iTask);
> +retry:
> +    iTask.task = iscsi_write16_task(iscsilun->iscsi, iscsilun->lun, lba,
> +                                    data, num_sectors * iscsilun->block_size,
> +                                    iscsilun->block_size, 0, 0, 0, 0, 0,
> +                                    iscsi_co_generic_cb, &iTask);
> +    if (iTask.task == NULL) {
> +        g_free(buf);
> +        return -EIO;
>      }
> -    memset(acb->task, 0, sizeof(struct scsi_task));
> -
> -    acb->task->xfer_dir = SCSI_XFER_WRITE;
> -    acb->task->cdb_size = 16;
> -    acb->task->cdb[0] = 0x8a;
> -    lba = sector_qemu2lun(acb->sector_num, acb->iscsilun);
> -    *(uint32_t *)&acb->task->cdb[2]  = htonl(lba >> 32);
> -    *(uint32_t *)&acb->task->cdb[6]  = htonl(lba & 0xffffffff);
> -    num_sectors = sector_qemu2lun(acb->nb_sectors, acb->iscsilun);
> -    *(uint32_t *)&acb->task->cdb[10] = htonl(num_sectors);
> -    acb->task->expxferlen = size;
> -
>  #if defined(LIBISCSI_FEATURE_IOVECTOR)
> -    ret = iscsi_scsi_command_async(iscsi, acb->iscsilun->lun, acb->task,
> -                                   iscsi_aio_write16_cb,
> -                                   NULL,
> -                                   acb);
> -#else
> -    ret = iscsi_scsi_command_async(iscsi, acb->iscsilun->lun, acb->task,
> -                                   iscsi_aio_write16_cb,
> -                                   &data,
> -                                   acb);
> +    scsi_task_set_iov_out(iTask.task, (struct scsi_iovec *) iov->iov,
> +                          iov->niov);
>  #endif
> -    if (ret != 0) {
> -        scsi_free_scsi_task(acb->task);
> -        g_free(acb->buf);
> -        return -1;
> +    while (!iTask.complete) {
> +        iscsi_set_events(iscsilun);
> +        qemu_coroutine_yield();
>      }
>  
> -#if defined(LIBISCSI_FEATURE_IOVECTOR)
> -    scsi_task_set_iov_out(acb->task, (struct scsi_iovec*) acb->qiov->iov, 
> acb->qiov->niov);
> -#endif
> -
> -    return 0;
> -}
> -
> -static BlockDriverAIOCB *
> -iscsi_aio_writev(BlockDriverState *bs, int64_t sector_num,
> -                 QEMUIOVector *qiov, int nb_sectors,
> -                 BlockDriverCompletionFunc *cb,
> -                 void *opaque)
> -{
> -    IscsiLun *iscsilun = bs->opaque;
> -    IscsiAIOCB *acb;
> -
> -    if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
> -        return NULL;
> +    if (iTask.task != NULL) {
> +        scsi_free_scsi_task(iTask.task);
> +        iTask.task = NULL;
>      }
>  
> -    acb = qemu_aio_get(&iscsi_aiocb_info, bs, cb, opaque);
> -    trace_iscsi_aio_writev(iscsilun->iscsi, sector_num, nb_sectors, opaque, 
> acb);
> -
> -    acb->iscsilun    = iscsilun;
> -    acb->qiov        = qiov;
> -    acb->nb_sectors  = nb_sectors;
> -    acb->sector_num  = sector_num;
> -    acb->retries     = ISCSI_CMD_RETRIES;
> -
> -    if (iscsi_aio_writev_acb(acb) != 0) {
> -        qemu_aio_release(acb);
> -        return NULL;
> +    if (iTask.do_retry) {
> +        goto retry;
>      }
>  
> -    iscsi_set_events(iscsilun);
> -    return &acb->common;
> -}
> -
> -static int
> -iscsi_aio_readv_acb(IscsiAIOCB *acb);
> -
> -static void
> -iscsi_aio_read16_cb(struct iscsi_context *iscsi, int status,
> -                    void *command_data, void *opaque)
> -{
> -    IscsiAIOCB *acb = opaque;
> -
> -    trace_iscsi_aio_read16_cb(iscsi, status, acb, acb->canceled);
> -
> -    if (acb->canceled != 0) {
> -        return;
> -    }
> +    g_free(buf);
>  
> -    acb->status = 0;
> -    if (status != 0) {
> -        if (status == SCSI_STATUS_CHECK_CONDITION
> -            && acb->task->sense.key == SCSI_SENSE_UNIT_ATTENTION
> -            && acb->retries-- > 0) {
> -            scsi_free_scsi_task(acb->task);
> -            acb->task = NULL;
> -            if (iscsi_aio_readv_acb(acb) == 0) {
> -                iscsi_set_events(acb->iscsilun);
> -                return;
> -            }
> -        }
> -        error_report("Failed to read16 data from iSCSI lun. %s",
> -                     iscsi_get_error(iscsi));
> -        acb->status = -EIO;
> +    if (iTask.status != SCSI_STATUS_GOOD) {
> +        return -EIO;
>      }
>  
> -    iscsi_schedule_bh(acb);
> +    return 0;
>  }
>  
> -static int
> -iscsi_aio_readv_acb(IscsiAIOCB *acb)
> +static int coroutine_fn iscsi_co_readv(BlockDriverState *bs,
> +                                       int64_t sector_num, int nb_sectors,
> +                                       QEMUIOVector *iov)
>  {
> -    struct iscsi_context *iscsi = acb->iscsilun->iscsi;
> -    size_t size;
> +    IscsiLun *iscsilun = bs->opaque;
> +    struct IscsiTask iTask;
>      uint64_t lba;
>      uint32_t num_sectors;
> -    int ret;
>  #if !defined(LIBISCSI_FEATURE_IOVECTOR)
>      int i;
>  #endif
>  
> -    acb->canceled    = 0;
> -    acb->bh          = NULL;
> -    acb->status      = -EINPROGRESS;
> -    acb->buf         = NULL;
> -
> -    size = acb->nb_sectors * BDRV_SECTOR_SIZE;
> -
> -    acb->task = malloc(sizeof(struct scsi_task));
> -    if (acb->task == NULL) {
> -        error_report("iSCSI: Failed to allocate task for scsi READ16 "
> -                     "command. %s", iscsi_get_error(iscsi));
> -        return -1;
> +    if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
> +        return -EINVAL;
>      }
> -    memset(acb->task, 0, sizeof(struct scsi_task));
>  
> -    acb->task->xfer_dir = SCSI_XFER_READ;
> -    acb->task->expxferlen = size;
> -    lba = sector_qemu2lun(acb->sector_num, acb->iscsilun);
> -    num_sectors = sector_qemu2lun(acb->nb_sectors, acb->iscsilun);
> +    lba = sector_qemu2lun(sector_num, iscsilun);
> +    num_sectors = sector_qemu2lun(nb_sectors, iscsilun);
>  
> -    switch (acb->iscsilun->type) {
> +    iscsi_co_init_iscsitask(iscsilun, &iTask);
> +retry:
> +    switch (iscsilun->type) {
>      case TYPE_DISK:
> -        acb->task->cdb_size = 16;
> -        acb->task->cdb[0]  = 0x88;
> -        *(uint32_t *)&acb->task->cdb[2]  = htonl(lba >> 32);
> -        *(uint32_t *)&acb->task->cdb[6]  = htonl(lba & 0xffffffff);
> -        *(uint32_t *)&acb->task->cdb[10] = htonl(num_sectors);
> +        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);
>          break;
>      default:
> -        acb->task->cdb_size = 10;
> -        acb->task->cdb[0]  = 0x28;
> -        *(uint32_t *)&acb->task->cdb[2] = htonl(lba);
> -        *(uint16_t *)&acb->task->cdb[7] = htons(num_sectors);
> +        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);
>          break;
>      }
> -
> -    ret = iscsi_scsi_command_async(iscsi, acb->iscsilun->lun, acb->task,
> -                                   iscsi_aio_read16_cb,
> -                                   NULL,
> -                                   acb);
> -    if (ret != 0) {
> -        scsi_free_scsi_task(acb->task);
> -        return -1;
> +    if (iTask.task == NULL) {
> +        return -EIO;
>      }
> -
>  #if defined(LIBISCSI_FEATURE_IOVECTOR)
> -    scsi_task_set_iov_in(acb->task, (struct scsi_iovec*) acb->qiov->iov, 
> acb->qiov->niov);
> +    scsi_task_set_iov_in(iTask.task, (struct scsi_iovec *) iov->iov, 
> iov->niov);
>  #else
> -    for (i = 0; i < acb->qiov->niov; i++) {
> -        scsi_task_add_data_in_buffer(acb->task,
> -                acb->qiov->iov[i].iov_len,
> -                acb->qiov->iov[i].iov_base);
> +    for (i = 0; i < iov->niov; i++) {
> +        scsi_task_add_data_in_buffer(iTask.task,
> +                                     iov->iov[i].iov_len,
> +                                     iov->iov[i].iov_base);
>      }
>  #endif
> -    return 0;
> -}
> -
> -static BlockDriverAIOCB *
> -iscsi_aio_readv(BlockDriverState *bs, int64_t sector_num,
> -                QEMUIOVector *qiov, int nb_sectors,
> -                BlockDriverCompletionFunc *cb,
> -                void *opaque)
> -{
> -    IscsiLun *iscsilun = bs->opaque;
> -    IscsiAIOCB *acb;
> -
> -    if (!is_request_lun_aligned(sector_num, nb_sectors, iscsilun)) {
> -        return NULL;
> -    }
>  
> -    acb = qemu_aio_get(&iscsi_aiocb_info, bs, cb, opaque);
> -    trace_iscsi_aio_readv(iscsilun->iscsi, sector_num, nb_sectors, opaque, 
> acb);
> -
> -    acb->nb_sectors  = nb_sectors;
> -    acb->sector_num  = sector_num;
> -    acb->iscsilun    = iscsilun;
> -    acb->qiov        = qiov;
> -    acb->retries     = ISCSI_CMD_RETRIES;
> -
> -    if (iscsi_aio_readv_acb(acb) != 0) {
> -        qemu_aio_release(acb);
> -        return NULL;
> +    while (!iTask.complete) {
> +        iscsi_set_events(iscsilun);
> +        qemu_coroutine_yield();
>      }
>  
> -    iscsi_set_events(iscsilun);
> -    return &acb->common;
> -}
> -
> -static int
> -iscsi_aio_flush_acb(IscsiAIOCB *acb);
> -
> -static void
> -iscsi_synccache10_cb(struct iscsi_context *iscsi, int status,
> -                     void *command_data, void *opaque)
> -{
> -    IscsiAIOCB *acb = opaque;
> -
> -    if (acb->canceled != 0) {
> -        return;
> +    if (iTask.task != NULL) {
> +        scsi_free_scsi_task(iTask.task);
> +        iTask.task = NULL;
>      }
>  
> -    acb->status = 0;
> -    if (status != 0) {
> -        if (status == SCSI_STATUS_CHECK_CONDITION
> -            && acb->task->sense.key == SCSI_SENSE_UNIT_ATTENTION
> -            && acb->retries-- > 0) {
> -            scsi_free_scsi_task(acb->task);
> -            acb->task = NULL;
> -            if (iscsi_aio_flush_acb(acb) == 0) {
> -                iscsi_set_events(acb->iscsilun);
> -                return;
> -            }
> -        }
> -        error_report("Failed to sync10 data on iSCSI lun. %s",
> -                     iscsi_get_error(iscsi));
> -        acb->status = -EIO;
> +    if (iTask.do_retry) {
> +        goto retry;
>      }
>  
> -    iscsi_schedule_bh(acb);
> -}
> -
> -static int
> -iscsi_aio_flush_acb(IscsiAIOCB *acb)
> -{
> -    struct iscsi_context *iscsi = acb->iscsilun->iscsi;
> -
> -    acb->canceled   = 0;
> -    acb->bh         = NULL;
> -    acb->status     = -EINPROGRESS;
> -    acb->buf        = NULL;
> -
> -    acb->task = iscsi_synchronizecache10_task(iscsi, acb->iscsilun->lun,
> -                                         0, 0, 0, 0,
> -                                         iscsi_synccache10_cb,
> -                                         acb);
> -    if (acb->task == NULL) {
> -        error_report("iSCSI: Failed to send synchronizecache10 command. %s",
> -                     iscsi_get_error(iscsi));
> -        return -1;
> +    if (iTask.status != SCSI_STATUS_GOOD) {
> +        return -EIO;
>      }
>  
>      return 0;
>  }
>  
> -static BlockDriverAIOCB *
> -iscsi_aio_flush(BlockDriverState *bs,
> -                BlockDriverCompletionFunc *cb, void *opaque)
> +static int coroutine_fn iscsi_co_flush(BlockDriverState *bs)
>  {
>      IscsiLun *iscsilun = bs->opaque;
> +    struct IscsiTask iTask;
>  
> -    IscsiAIOCB *acb;
> +    iscsi_co_init_iscsitask(iscsilun, &iTask);
>  
> -    acb = qemu_aio_get(&iscsi_aiocb_info, bs, cb, opaque);
> +retry:
> +    if (iscsi_synchronizecache10_task(iscsilun->iscsi, iscsilun->lun, 0, 0, 
> 0,
> +                                      0, iscsi_co_generic_cb, &iTask) == 
> NULL) {
> +        return -EIO;
> +    }
>  
> -    acb->iscsilun    = iscsilun;
> -    acb->retries     = ISCSI_CMD_RETRIES;
> +    while (!iTask.complete) {
> +        iscsi_set_events(iscsilun);
> +        qemu_coroutine_yield();
> +    }
>  
> -    if (iscsi_aio_flush_acb(acb) != 0) {
> -        qemu_aio_release(acb);
> -        return NULL;
> +    if (iTask.task != NULL) {
> +        scsi_free_scsi_task(iTask.task);
> +        iTask.task = NULL;
>      }
>  
> -    iscsi_set_events(iscsilun);
> +    if (iTask.do_retry) {
> +        goto retry;
> +    }
>  
> -    return &acb->common;
> +    if (iTask.status != SCSI_STATUS_GOOD) {
> +        return -EIO;
> +    }
> +
> +    return 0;
>  }
>  
>  #ifdef __linux__
> @@ -1599,12 +1409,11 @@ static BlockDriver bdrv_iscsi = {
>  #if defined(LIBISCSI_FEATURE_IOVECTOR)
>      .bdrv_co_get_block_status = iscsi_co_get_block_status,
>  #endif
> -    .bdrv_co_discard      = iscsi_co_discard,
> -    .bdrv_co_write_zeroes = iscsi_co_write_zeroes,
> -
> -    .bdrv_aio_readv  = iscsi_aio_readv,
> -    .bdrv_aio_writev = iscsi_aio_writev,
> -    .bdrv_aio_flush  = iscsi_aio_flush,
> +    .bdrv_co_discard       = iscsi_co_discard,
> +    .bdrv_co_write_zeroes  = iscsi_co_write_zeroes,
> +    .bdrv_co_readv         = iscsi_co_readv,
> +    .bdrv_co_writev        = iscsi_co_writev,
> +    .bdrv_co_flush_to_disk = iscsi_co_flush,
>  
>      .bdrv_has_zero_init            = iscsi_has_zero_init,
>      .bdrv_has_discard_zeroes       = iscsi_has_discard_zeroes,
>