Re: [Qemu-devel] [v1 Patch 3/10]Qemu: Cmd "block_set_hostcache" for dynamic cache change

[Supriya Kannery]

On 07/11/2012 07:46 PM, Luiz Capitulino wrote:
> On Sat, 16 Jun 2012 02:17:30 +0530
> Supriya Kannery<address@hidden>  wrote:
>
> > New command "block_set_hostcache" added for dynamically changing
> > host pagecache setting of a block device.
> >
> > Usage:
> >   block_set_hostcache<device>  <option>
> >     <device>  = block device
> >     <option>  = on/off
> >
> > Example:
> >   (qemu) block_set_hostcache ide0-hd0 off
> >
> > Signed-off-by: Supriya Kannery<address@hidden>
> >
> > ---
> >   block.c         |   54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >   block.h         |    2 ++
> >   blockdev.c      |   26 ++++++++++++++++++++++++++
> >   blockdev.h      |    2 ++
> >   hmp-commands.hx |   14 ++++++++++++++
> >   qmp-commands.hx |   27 +++++++++++++++++++++++++++
> >   6 files changed, 125 insertions(+)
> >
> > Index: qemu/block.c
> > ===================================================================
> > --- qemu.orig/block.c
> > +++ qemu/block.c
> > @@ -858,6 +858,35 @@ unlink_and_fail:
> >       return ret;
> >   }
> >
> > +int bdrv_reopen(BlockDriverState *bs, int bdrv_flags)
> > +{
> > +    BlockDriver *drv = bs->drv;
> > +    int ret = 0, open_flags;
> > +
> > +    /* Quiesce IO for the given block device */
> > +    qemu_aio_flush();
> > +    ret = bdrv_flush(bs);
> > +    if (ret != 0) {
> > +        qerror_report(QERR_DATA_SYNC_FAILED, bs->device_name);
>
> Please, use error_set() instead of qerror_report() and as Kevin said IOError
> seems enough here.

Sure, will replace qemu_aio_flush() with bdrv_drain_all()
and qerror_report() with error_set().

Combination of bdrv_drain_all() and bdrv_flush(), should
help in flushing out the specific disk.

-thanks, Supriya