Re: [Qemu-devel] [PATCH] qmp: add BLOCK_MEDIUM_EJECT event

[Luiz Capitulino <lcapitulino@redhat.com>]

On Fri, 27 Jan 2012 13:10:39 +0100
Paolo Bonzini <pbonzini@redhat.com> wrote:

> On 01/24/2012 07:16 PM, Luiz Capitulino wrote:
> > @@ -237,6 +238,17 @@ static bool do_check_io_limits(BlockIOLimit *io_limits)
> >      return true;
> >  }
> >
> > +static void on_medium_eject(BlockDriverState *bs, int is_ejected)
> > +{
> > +    QObject *data;
> > +
> > +    data = qobject_from_jsonf("{ 'device': %s, 'ejected': %i }",
> > +                              bdrv_get_device_name(bs), is_ejected);
> > +    monitor_protocol_event(QEVENT_BLOCK_MEDIUM_EJECT, data);
> > +
> > +    qobject_decref(data);
> > +}
> > +
> >  DriveInfo *drive_init(QemuOpts *opts, int default_to_scsi)
> >  {
> >      const char *buf;
> > @@ -503,6 +515,7 @@ DriveInfo *drive_init(QemuOpts *opts, int default_to_scsi)
> >      QTAILQ_INSERT_TAIL(&drives, dinfo, next);
> >
> >      bdrv_set_on_error(dinfo->bdrv, on_read_error, on_write_error);
> > +    bdrv_dev_set_medium_eject_notify(dinfo->bdrv, on_medium_eject);
> >
> >      /* disk I/O throttling */
> >      bdrv_set_io_limits(dinfo->bdrv, &io_limits);
> 
> block.c/blockdev.c separation is nice, but do we really need a function 
> pointer?  Also, we're already emitting the BLOCK_IO_ERROR event in 
> block.c; is that another place to cleanup, or is this overkill and we 
> can just put bdrv_dev_medium_eject_notify in block.c?

This patch has changed after this whole discussion. My current version (not
posted yet) adds a bdrv_emit_qmp_error_event() function to block.c and call
it from bdrv_eject(). But that accounts only for the guest initiated ejects...

> > diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c
> > index 0adb27b..4b4bc61 100644
> > --- a/hw/ide/atapi.c
> > +++ b/hw/ide/atapi.c
> > @@ -885,6 +885,7 @@ static void cmd_start_stop_unit(IDEState*s, uint8_t*  buf)
> >           }
> >           bdrv_eject(s->bs, !start);
> >           s->tray_open = !start;
> > +        bdrv_dev_medium_eject_notify(s->bs, !start);
> >       }
> >
> >       ide_atapi_cmd_ok(s);
> > diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
> > index 5d8bf53..35e55f4 100644
> > --- a/hw/scsi-disk.c
> > +++ b/hw/scsi-disk.c
> > @@ -1061,6 +1061,7 @@ static int scsi_disk_emulate_start_stop(SCSIDiskReq *r)
> >           }
> >           bdrv_eject(s->qdev.conf.bs, !start);
> >           s->tray_open = !start;
> > +        bdrv_dev_medium_eject_notify(s->qdev.conf.bs, !start);
> >       }
> >       return 0;
> >   }
> 
> Can you do the call directly in bdrv_eject (but I would skip 
> bdrv_close)?  The only other place where bdrv_eject is called is from 
> block/raw.c's raw_eject, but I think you should only emit the event if 
> bs->device_name[0] (otherwise the event is quite useless) and bs->file 
> will fail the test.

Good point.