[PATCH v2 for 7.1 1/1] block: add 'force' parameter to 'blockdev-change-medium' command

["Denis V. Lunev" <den@openvz.org>]

'blockdev-change-medium' is a convinient wrapper for the following
sequence of commands:
 * blockdev-open-tray
 * blockdev-remove-medium
 * blockdev-insert-medium
 * blockdev-close-tray
and should be used f.e. to change ISO image inside the CD-ROM tray.
Though the guest could lock the tray and some linux guests like
CentOS 8.5 actually does that. In this case the execution if this
command results in the error like the following:
  Device 'scsi0-0-1-0' is locked and force was not specified,
  wait for tray to open and try again.

This situation is could be resolved 'blockdev-open-tray' by passing
flag 'force' inside. Thus is seems reasonable to add the same
capability for 'blockdev-change-medium' too.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Hanna Reitz <hreitz@redhat.com>
CC: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
CC: Eric Blake <eblake@redhat.com>
CC: Markus Armbruster <armbru@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@openvz.org>
---
 block/qapi-sysemu.c |  3 ++-
 hmp-commands.hx     | 11 +++++++----
 monitor/hmp-cmds.c  |  4 +++-
 qapi/block.json     |  6 ++++++
 ui/cocoa.m          |  1 +
 5 files changed, 19 insertions(+), 6 deletions(-)

Changes from v1:
- added kludge to Objective C code
- simplified a bit call of do_open_tray() (thanks, Vova!)
- added record to hmp-command.hx

diff --git a/block/qapi-sysemu.c b/block/qapi-sysemu.c
index 8498402ad4..680c7ee342 100644
--- a/block/qapi-sysemu.c
+++ b/block/qapi-sysemu.c
@@ -318,6 +318,7 @@ void qmp_blockdev_change_medium(bool has_device, const char *device,
                                 bool has_id, const char *id,
                                 const char *filename,
                                 bool has_format, const char *format,
+                                bool has_force, bool force,
                                 bool has_read_only,
                                 BlockdevChangeReadOnlyMode read_only,
                                 Error **errp)
@@ -380,7 +381,7 @@ void qmp_blockdev_change_medium(bool has_device, const char *device,
 
     rc = do_open_tray(has_device ? device : NULL,
                       has_id ? id : NULL,
-                      false, &err);
+                      force, &err);
     if (rc && rc != -ENOSYS) {
         error_propagate(errp, err);
         goto fail;
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 8476277aa9..6ec593ea08 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -202,9 +202,9 @@ ERST
 
     {
         .name       = "change",
-        .args_type  = "device:B,target:F,arg:s?,read-only-mode:s?",
-        .params     = "device filename [format [read-only-mode]]",
-        .help       = "change a removable medium, optional format",
+        .args_type  = "device:B,force:-f,target:F,arg:s?,read-only-mode:s?",
+        .params     = "device [-f] filename [format [read-only-mode]]",
+        .help       = "change a removable medium, optional format, use -f to force the operation",
         .cmd        = hmp_change,
     },
 
@@ -212,11 +212,14 @@ SRST
 ``change`` *device* *setting*
   Change the configuration of a device.
 
-  ``change`` *diskdevice* *filename* [*format* [*read-only-mode*]]
+  ``change`` *diskdevice* [-f] *filename* [*format* [*read-only-mode*]]
     Change the medium for a removable disk device to point to *filename*. eg::
 
       (qemu) change ide1-cd0 /path/to/some.iso
 
+    ``-f``
+      forces the operation even if the guest has locked the tray.
+
     *format* is optional.
 
     *read-only-mode* may be used to change the read-only status of the device.
diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
index 634968498b..d8b98bed6c 100644
--- a/monitor/hmp-cmds.c
+++ b/monitor/hmp-cmds.c
@@ -1472,6 +1472,7 @@ void hmp_change(Monitor *mon, const QDict *qdict)
     const char *target = qdict_get_str(qdict, "target");
     const char *arg = qdict_get_try_str(qdict, "arg");
     const char *read_only = qdict_get_try_str(qdict, "read-only-mode");
+    bool force = qdict_get_try_bool(qdict, "force", false);
     BlockdevChangeReadOnlyMode read_only_mode = 0;
     Error *err = NULL;
 
@@ -1508,7 +1509,8 @@ void hmp_change(Monitor *mon, const QDict *qdict)
         }
 
         qmp_blockdev_change_medium(true, device, false, NULL, target,
-                                   !!arg, arg, !!read_only, read_only_mode,
+                                   !!arg, arg, true, force,
+                                   !!read_only, read_only_mode,
                                    &err);
     }
 
diff --git a/qapi/block.json b/qapi/block.json
index 82fcf2c914..3f100d4887 100644
--- a/qapi/block.json
+++ b/qapi/block.json
@@ -326,6 +326,11 @@
 # @read-only-mode: change the read-only mode of the device; defaults
 #                  to 'retain'
 #
+# @force: if false (the default), an eject request through blockdev-open-tray
+#         will be sent to the guest if it has locked the tray (and the tray
+#         will not be opened immediately); if true, the tray will be opened
+#         regardless of whether it is locked. (since 7.1)
+#
 # Features:
 # @deprecated: Member @device is deprecated.  Use @id instead.
 #
@@ -367,6 +372,7 @@
             '*id': 'str',
             'filename': 'str',
             '*format': 'str',
+            '*force': 'bool',
             '*read-only-mode': 'BlockdevChangeReadOnlyMode' } }
 
 
diff --git a/ui/cocoa.m b/ui/cocoa.m
index c4e5468f9e..a931174397 100644
--- a/ui/cocoa.m
+++ b/ui/cocoa.m
@@ -1529,6 +1529,7 @@ - (void)changeDeviceMedia:(id)sender
                                        false, NULL,
                                        [file cStringUsingEncoding:
                                                  NSASCIIStringEncoding],
+                                       true, false,
                                        true, "raw",
                                        false, 0,
                                        &err);
-- 
2.32.0