Re: [Qemu-devel] [Qemu-block] [PATCH RFC v3 3/8] block: add throttle block filter driver

[Manos Pitsidianakis]

On Mon, Jun 26, 2017 at 03:30:55PM +0100, Stefan Hajnoczi wrote:
> > +static BlockDriver bdrv_throttle = {
> > +    .format_name                        =   "throttle",
> > +    .protocol_name                      =   "throttle",
> > +    .instance_size                      =   sizeof(ThrottleGroupMember),
> > +
> > +    .bdrv_file_open                     =   throttle_open,
> > +    .bdrv_close                         =   throttle_close,
> > +    .bdrv_co_flush                      =   throttle_co_flush,
> > +
> > +    .bdrv_child_perm                    =   bdrv_filter_default_perms,
> > +
> > +    .bdrv_getlength                     =   throttle_getlength,
> > +
> > +    .bdrv_co_preadv                     =   throttle_co_preadv,
> > +    .bdrv_co_pwritev                    =   throttle_co_pwritev,
> > +
> > +    .bdrv_co_pwrite_zeroes              =   throttle_co_pwrite_zeroes,
> > +    .bdrv_co_pdiscard                   =   throttle_co_pdiscard,
> > +
> > +    .bdrv_recurse_is_first_non_filter   =   bdrv_recurse_is_first_non_filter,
> > +
> > +    .bdrv_attach_aio_context            =   throttle_attach_aio_context,
> > +    .bdrv_detach_aio_context            =   throttle_detach_aio_context,
> > +
> > +    .bdrv_reopen_prepare                =   throttle_reopen_prepare,
> > +    .bdrv_reopen_commit                 =   throttle_reopen_commit,
> > +    .bdrv_reopen_abort                  =   throttle_reopen_abort,
> > +
> > +    .is_filter                          =   true,
> > +};
>
> Missing:
> bdrv_co_get_block_status()
> bdrv_truncate()
> bdrv_get_info()
> bdrv_probe_blocksizes()
> bdrv_probe_geometry()
> bdrv_media_changed()
> bdrv_eject()
> bdrv_lock_medium()
> bdrv_co_ioctl()
>
> See block/raw-format.c.
>
> I think most of these could be modified in block.c or block/io.c to
> automatically call bs->file's function if drv doesn't implement them.
> This way all block drivers would transparently pass them through by
> default and block/raw-format.c code could be eliminated.

Are these truly necessary? Because other filter drivers (ie quorum, 
blkverify) don't implement them.

signature.asc
Description: PGP signature