| Message ID | 1305551097-11387-5-git-send-email-armbru@redhat.com |
|---|---|
| State | New |
| Headers | show |
Am 16.05.2011 15:04, schrieb Markus Armbruster: > query-block's specification documents response member "type" with > values "hd", "cdrom", "floppy", "unknown". > > Its value is unreliable: a block device used as floppy has type > "floppy" if created with if=floppy, but type "hd" if created with > if=none. > > That's because with if=none, the type is at best a declaration of > intent: the drive can be connected to any guest device. Its type is > really the guest device's business. Reporting it here is wrong. > > No known user of QMP uses "type". It's unlikely that any unknown > users exist, because its value is useless unless you know how the > block device was created. But then you also know the true value. > > Fixing the broken value risks breaking (hypothetical!) clients that > somehow rely on the current behavior. Not fixing the value risks > breaking (hypothetical!) clients that rely on the value to be > accurate. Can't entirely avoid hypothetical lossage. Change the > value to be always "unknown". > > This makes "info block" always report "type=unknown". Pointless. > Change it to not report the type. > > Signed-off-by: Markus Armbruster <armbru@redhat.com> Luiz/Anthony, I'm not sure if Markus asked you, but I'm waiting for an Ack from one of you here before merging this series. Just in case someone wonders why nothing has happened yet. Kevin
On Wed, 18 May 2011 14:44:11 +0200 Kevin Wolf <kwolf@redhat.com> wrote: > Am 16.05.2011 15:04, schrieb Markus Armbruster: > > query-block's specification documents response member "type" with > > values "hd", "cdrom", "floppy", "unknown". > > > > Its value is unreliable: a block device used as floppy has type > > "floppy" if created with if=floppy, but type "hd" if created with > > if=none. > > > > That's because with if=none, the type is at best a declaration of > > intent: the drive can be connected to any guest device. Its type is > > really the guest device's business. Reporting it here is wrong. > > > > No known user of QMP uses "type". It's unlikely that any unknown > > users exist, because its value is useless unless you know how the > > block device was created. But then you also know the true value. > > > > Fixing the broken value risks breaking (hypothetical!) clients that > > somehow rely on the current behavior. Not fixing the value risks > > breaking (hypothetical!) clients that rely on the value to be > > accurate. Can't entirely avoid hypothetical lossage. Change the > > value to be always "unknown". > > > > This makes "info block" always report "type=unknown". Pointless. > > Change it to not report the type. > > > > Signed-off-by: Markus Armbruster <armbru@redhat.com> > > Luiz/Anthony, I'm not sure if Markus asked you, but I'm waiting for an > Ack from one of you here before merging this series. Just in case > someone wonders why nothing has happened yet. Sorry for the delay: ACK Honestly, I'm a bit reluctant because we don't provide an alternative. Yes, I understand the value is unreliable, but as far as I understand it has reliable usages and it's the only way a client can currently learn about the VM's block devices. However, we don't want new clients to rely on this field, we're not sure it's used and we're not breaking the protocol, anyway.
diff --git a/block.c b/block.c index f403718..9de7450 100644 --- a/block.c +++ b/block.c @@ -1704,9 +1704,8 @@ static void bdrv_print_dict(QObject *obj, void *opaque) bs_dict = qobject_to_qdict(obj); - monitor_printf(mon, "%s: type=%s removable=%d", + monitor_printf(mon, "%s: removable=%d", qdict_get_str(bs_dict, "device"), - qdict_get_str(bs_dict, "type"), qdict_get_bool(bs_dict, "removable")); if (qdict_get_bool(bs_dict, "removable")) { @@ -1747,23 +1746,10 @@ void bdrv_info(Monitor *mon, QObject **ret_data) QTAILQ_FOREACH(bs, &bdrv_states, list) { QObject *bs_obj; - const char *type = "unknown"; - - switch(bs->type) { - case BDRV_TYPE_HD: - type = "hd"; - break; - case BDRV_TYPE_CDROM: - type = "cdrom"; - break; - case BDRV_TYPE_FLOPPY: - type = "floppy"; - break; - } - bs_obj = qobject_from_jsonf("{ 'device': %s, 'type': %s, " + bs_obj = qobject_from_jsonf("{ 'device': %s, 'type': 'unknown', " "'removable': %i, 'locked': %i }", - bs->device_name, type, bs->removable, + bs->device_name, bs->removable, bs->locked); if (bs->drv) { diff --git a/qmp-commands.hx b/qmp-commands.hx index fbd98ee..a9f109a 100644 --- a/qmp-commands.hx +++ b/qmp-commands.hx @@ -1039,7 +1039,8 @@ Each json-object contain the following: - "device": device name (json-string) - "type": device type (json-string) - - Possible values: "hd", "cdrom", "floppy", "unknown" + - deprecated, retained for backward compatibility + - Possible values: "unknown" - "removable": true if the device is removable, false otherwise (json-bool) - "locked": true if the device is locked, false otherwise (json-bool) - "inserted": only present if the device is inserted, it is a json-object @@ -1070,25 +1071,25 @@ Example: "encrypted":false, "file":"disks/test.img" }, - "type":"hd" + "type":"unknown" }, { "device":"ide1-cd0", "locked":false, "removable":true, - "type":"cdrom" + "type":"unknown" }, { "device":"floppy0", "locked":false, "removable":true, - "type": "floppy" + "type":"unknown" }, { "device":"sd0", "locked":false, "removable":true, - "type":"floppy" + "type":"unknown" } ] }
query-block's specification documents response member "type" with values "hd", "cdrom", "floppy", "unknown". Its value is unreliable: a block device used as floppy has type "floppy" if created with if=floppy, but type "hd" if created with if=none. That's because with if=none, the type is at best a declaration of intent: the drive can be connected to any guest device. Its type is really the guest device's business. Reporting it here is wrong. No known user of QMP uses "type". It's unlikely that any unknown users exist, because its value is useless unless you know how the block device was created. But then you also know the true value. Fixing the broken value risks breaking (hypothetical!) clients that somehow rely on the current behavior. Not fixing the value risks breaking (hypothetical!) clients that rely on the value to be accurate. Can't entirely avoid hypothetical lossage. Change the value to be always "unknown". This makes "info block" always report "type=unknown". Pointless. Change it to not report the type. Signed-off-by: Markus Armbruster <armbru@redhat.com> --- block.c | 20 +++----------------- qmp-commands.hx | 11 ++++++----- 2 files changed, 9 insertions(+), 22 deletions(-)