Re: [Qemu-devel] [v7 Patch 1/5]Qemu: Enhance "info block" to display host cache setting

[Kevin Wolf <kwolf@redhat.com>]

Am 11.10.2011 05:10, schrieb Supriya Kannery:
> Enhance "info block" to display hostcache setting for each
> block device.
> 
> Example:
> (qemu) info block
> ide0-hd0: removable=0 file=../sles11-32.raw ro=0 drv=raw encrypted=0
> 
> Enhanced to display "hostcache" setting:
> (qemu) info block
> ide0-hd0: removable=0 hostcache=1 file=../sles11-32.raw ro=0 drv=raw encrypted=0
> 
> Signed-off-by: Supriya Kannery <supriyak@linux.vnet.ibm.com>
> 
> ---
>  block.c         |   20 ++++++++++++++++----
>  qmp-commands.hx |    2 ++
>  2 files changed, 18 insertions(+), 4 deletions(-)
> 
> Index: qemu/qmp-commands.hx
> ===================================================================
> --- qemu.orig/qmp-commands.hx
> +++ qemu/qmp-commands.hx
> @@ -1142,6 +1142,7 @@ Each json-object contain the following:
>  - "locked": true if the device is locked, false otherwise (json-bool)
>  - "tray-open": only present if removable, true if the device has a tray,
>                 and it is open (json-bool)
> +- "hostcache": true if host pagecache enabled, false otherwise (json-bool)
>  - "inserted": only present if the device is inserted, it is a json-object
>     containing the following:
>           - "file": device file name (json-string)
> @@ -1163,6 +1164,7 @@ Example:
>           {
>              "device":"ide0-hd0",
>              "locked":false,
> +            "hostcache":false,
>              "removable":false,
>              "inserted":{
>                 "ro":false,
> Index: qemu/block.c
> ===================================================================
> --- qemu.orig/block.c
> +++ qemu/block.c
> @@ -1866,6 +1866,15 @@ static void bdrv_print_dict(QObject *obj
>          monitor_printf(mon, " tray-open=%d",
>                         qdict_get_bool(bs_dict, "tray-open"));
>      }
> +
> +    if (qdict_haskey(bs_dict, "open_flags")) {
> +        int open_flags = qdict_get_int(bs_dict, "open_flags");
> +        if (open_flags & BDRV_O_NOCACHE)
> +            monitor_printf(mon, " hostcache=0");
> +        else
> +            monitor_printf(mon, " hostcache=1");

Coding style requires braces.

> +    }
> +
>      if (qdict_haskey(bs_dict, "inserted")) {
>          QDict *qdict = qobject_to_qdict(qdict_get(bs_dict, "inserted"));
>  
> @@ -1903,11 +1912,14 @@ void bdrv_info(Monitor *mon, QObject **r
>          QDict *bs_dict;
>  
>          bs_obj = qobject_from_jsonf("{ 'device': %s, 'type': 'unknown', "
> -                                    "'removable': %i, 'locked': %i }",
> +                                    "'removable': %i, 'locked': %i, "
> +                                    "'hostcache': %i }",
>                                      bs->device_name,
>                                      bdrv_dev_has_removable_media(bs),
> -                                    bdrv_dev_is_medium_locked(bs));
> +                                    bdrv_dev_is_medium_locked(bs),
> +                                    !(bs->open_flags & BDRV_O_NOCACHE));
>          bs_dict = qobject_to_qdict(bs_obj);
> +        qdict_put(bs_dict, "open_flags", qint_from_int(bs->open_flags));

No. This adds a open_flags field to the QMP structure that is
transferred to clients. This is wrong, open_flags is an internal thing
that should never be visible on an interface.

In bdrv_print_dict, access the hostcache field that you introduced, it
provides the same information.

Kevin