Re: [Qemu-devel] [PATCH 08/22] iscsi: implement .bdrv_detach/attach_aio_context()

[Peter Lieven <pl@kamp.de>]

Am 01.05.2014 um 16:54 schrieb Stefan Hajnoczi <stefanha@redhat.com>:

> Drop the assumption that we're using the main AioContext for Linux
> AIO.  Convert qemu_aio_set_fd_handler() to aio_set_fd_handler() and
> timer_new_ms() to aio_timer_new().
> 
> The .bdrv_detach/attach_aio_context() interfaces also need to be
> implemented to move the fd and timer from the old to the new AioContext.
> 
> Cc: Peter Lieven <pl@kamp.de>
> Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> block/iscsi.c | 79 +++++++++++++++++++++++++++++++++++++++++------------------
> 1 file changed, 55 insertions(+), 24 deletions(-)
> 
> diff --git a/block/iscsi.c b/block/iscsi.c
> index a30202b..81e3ebd 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -47,6 +47,7 @@
> 
> typedef struct IscsiLun {
>     struct iscsi_context *iscsi;
> +    AioContext *aio_context;
>     int lun;
>     enum scsi_inquiry_peripheral_device_type type;
>     int block_size;
> @@ -69,6 +70,7 @@ typedef struct IscsiTask {
>     struct scsi_task *task;
>     Coroutine *co;
>     QEMUBH *bh;
> +    AioContext *aio_context;
> } IscsiTask;
> 
> typedef struct IscsiAIOCB {
> @@ -120,7 +122,7 @@ iscsi_schedule_bh(IscsiAIOCB *acb)
>     if (acb->bh) {
>         return;
>     }
> -    acb->bh = qemu_bh_new(iscsi_bh_cb, acb);
> +    acb->bh = aio_bh_new(acb->iscsilun->aio_context, iscsi_bh_cb, acb);
>     qemu_bh_schedule(acb->bh);
> }
> 
> @@ -156,7 +158,7 @@ iscsi_co_generic_cb(struct iscsi_context *iscsi, int status,
> 
> out:
>     if (iTask->co) {
> -        iTask->bh = qemu_bh_new(iscsi_co_generic_bh_cb, iTask);
> +        iTask->bh = aio_bh_new(iTask->aio_context, iscsi_co_generic_bh_cb, iTask);
>         qemu_bh_schedule(iTask->bh);
>     }
> }
> @@ -164,8 +166,9 @@ out:
> static void iscsi_co_init_iscsitask(IscsiLun *iscsilun, struct IscsiTask *iTask)
> {
>     *iTask = (struct IscsiTask) {
> -        .co         = qemu_coroutine_self(),
> -        .retries    = ISCSI_CMD_RETRIES,
> +        .co             = qemu_coroutine_self(),
> +        .retries        = ISCSI_CMD_RETRIES,
> +        .aio_context    = iscsilun->aio_context,
>     };
> }
> 
> @@ -196,7 +199,7 @@ iscsi_aio_cancel(BlockDriverAIOCB *blockacb)
>                                      iscsi_abort_task_cb, acb);
> 
>     while (acb->status == -EINPROGRESS) {
> -        qemu_aio_wait();
> +        aio_poll(bdrv_get_aio_context(blockacb->bs), true);
>     }
> }
> 
> @@ -219,10 +222,11 @@ iscsi_set_events(IscsiLun *iscsilun)
>     ev = POLLIN;
>     ev |= iscsi_which_events(iscsi);
>     if (ev != iscsilun->events) {
> -        qemu_aio_set_fd_handler(iscsi_get_fd(iscsi),
> -                      iscsi_process_read,
> -                      (ev & POLLOUT) ? iscsi_process_write : NULL,
> -                      iscsilun);
> +        aio_set_fd_handler(iscsilun->aio_context,
> +                           iscsi_get_fd(iscsi),
> +                           iscsi_process_read,
> +                           (ev & POLLOUT) ? iscsi_process_write : NULL,
> +                           iscsilun);
> 
>     }
> 
> @@ -620,7 +624,7 @@ static int iscsi_ioctl(BlockDriverState *bs, unsigned long int req, void *buf)
>         iscsi_aio_ioctl(bs, req, buf, ioctl_cb, &status);
> 
>         while (status == -EINPROGRESS) {
> -            qemu_aio_wait();
> +            aio_poll(bdrv_get_aio_context(bs), true);
>         }
> 
>         return 0;
> @@ -1110,6 +1114,40 @@ fail_with_err:
>     return NULL;
> }
> 
> +static void iscsi_detach_aio_context(BlockDriverState *bs)
> +{
> +    IscsiLun *iscsilun = bs->opaque;
> +
> +    aio_set_fd_handler(iscsilun->aio_context,
> +                       iscsi_get_fd(iscsilun->iscsi),
> +                       NULL, NULL, NULL);
> +    iscsilun->events = 0;
> +
> +    if (iscsilun->nop_timer) {
> +        timer_del(iscsilun->nop_timer);
> +        timer_free(iscsilun->nop_timer);
> +        iscsilun->nop_timer = NULL;
> +    }
> +}
> +
> +static void iscsi_attach_aio_context(BlockDriverState *bs,
> +                                     AioContext *new_context)
> +{
> +    IscsiLun *iscsilun = bs->opaque;
> +
> +    iscsilun->aio_context = new_context;
> +    iscsi_set_events(iscsilun);
> +
> +#if defined(LIBISCSI_FEATURE_NOP_COUNTER)
> +    /* Set up a timer for sending out iSCSI NOPs */
> +    iscsilun->nop_timer = aio_timer_new(iscsilun->aio_context,
> +                                        QEMU_CLOCK_REALTIME, SCALE_MS,
> +                                        iscsi_nop_timed_event, iscsilun);
> +    timer_mod(iscsilun->nop_timer,
> +              qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + NOP_INTERVAL);
> +#endif
> +}

Is it still guaranteed that iscsi_nop_timed_event for a target is not invoked
while we are in another function/callback of the iscsi driver for the same target?

Peter


> +
> /*
>  * We support iscsi url's on the form
>  * iscsi://[<username>%<password>@]<host>[:<port>]/<targetname>/<lun>
> @@ -1216,6 +1254,7 @@ static int iscsi_open(BlockDriverState *bs, QDict *options, int flags,
>     }
> 
>     iscsilun->iscsi = iscsi;
> +    iscsilun->aio_context = bdrv_get_aio_context(bs);
>     iscsilun->lun   = iscsi_url->lun;
>     iscsilun->has_write_same = true;
> 
> @@ -1289,11 +1328,7 @@ static int iscsi_open(BlockDriverState *bs, QDict *options, int flags,
>     scsi_free_scsi_task(task);
>     task = NULL;
> 
> -#if defined(LIBISCSI_FEATURE_NOP_COUNTER)
> -    /* Set up a timer for sending out iSCSI NOPs */
> -    iscsilun->nop_timer = timer_new_ms(QEMU_CLOCK_REALTIME, iscsi_nop_timed_event, iscsilun);
> -    timer_mod(iscsilun->nop_timer, qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + NOP_INTERVAL);
> -#endif
> +    iscsi_attach_aio_context(bs, iscsilun->aio_context);
> 
> out:
>     qemu_opts_del(opts);
> @@ -1321,11 +1356,7 @@ static void iscsi_close(BlockDriverState *bs)
>     IscsiLun *iscsilun = bs->opaque;
>     struct iscsi_context *iscsi = iscsilun->iscsi;
> 
> -    if (iscsilun->nop_timer) {
> -        timer_del(iscsilun->nop_timer);
> -        timer_free(iscsilun->nop_timer);
> -    }
> -    qemu_aio_set_fd_handler(iscsi_get_fd(iscsi), NULL, NULL, NULL);
> +    iscsi_detach_aio_context(bs);
>     iscsi_destroy_context(iscsi);
>     g_free(iscsilun->zeroblock);
>     memset(iscsilun, 0, sizeof(IscsiLun));
> @@ -1421,10 +1452,7 @@ static int iscsi_create(const char *filename, QEMUOptionParameter *options,
>     if (ret != 0) {
>         goto out;
>     }
> -    if (iscsilun->nop_timer) {
> -        timer_del(iscsilun->nop_timer);
> -        timer_free(iscsilun->nop_timer);
> -    }
> +    iscsi_detach_aio_context(bs);
>     if (iscsilun->type != TYPE_DISK) {
>         ret = -ENODEV;
>         goto out;
> @@ -1501,6 +1529,9 @@ static BlockDriver bdrv_iscsi = {
>     .bdrv_ioctl       = iscsi_ioctl,
>     .bdrv_aio_ioctl   = iscsi_aio_ioctl,
> #endif
> +
> +    .bdrv_detach_aio_context = iscsi_detach_aio_context,
> +    .bdrv_attach_aio_context = iscsi_attach_aio_context,
> };
> 
> static QemuOptsList qemu_iscsi_opts = {
> -- 
> 1.9.0
>