Add an option to qmp_blockdev_change_medium() which allows changing the
read-only status of the block device whose medium is changed.
Some drives do not have a inherently fixed read-only status; for
instance, floppy disks can be set read-only or writable independently of
the drive. Some users may find it useful to be able to therefore change
the read-only status of a block device when changing the medium.
Signed-off-by: Max Reitz <mre...@redhat.com>
---
blockdev.c | 24 +++++++++++++++++++++++-
hmp.c | 2 +-
qapi/block-core.json | 24 +++++++++++++++++++++++-
qmp-commands.hx | 24 +++++++++++++++++++++++-
qmp.c | 3 ++-
5 files changed, 72 insertions(+), 5 deletions(-)
diff --git a/blockdev.c b/blockdev.c
index e8947a5..84b2578 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1770,6 +1770,8 @@ static void qmp_bdrv_open_encrypted(BlockDriverState *bs,
const char *filename,
void qmp_blockdev_change_medium(const char *device, const char *filename,
bool has_format, const char *format,
+ bool has_read_only,
+ BlockdevChangeReadOnlyMode read_only,
Error **errp)
{
BlockBackend *blk;
@@ -1803,7 +1805,27 @@ void qmp_blockdev_change_medium(const char *device,
const char *filename,
goto out;
}
- bdrv_flags = bdrv_is_read_only(bs) ? 0 : BDRV_O_RDWR;
+ if (!has_read_only) {
+ read_only = BLOCKDEV_CHANGE_READ_ONLY_MODE_RETAIN;
+ }
+
+ switch (read_only) {
+ case BLOCKDEV_CHANGE_READ_ONLY_MODE_RETAIN:
+ bdrv_flags = bdrv_is_read_only(bs) ? 0 : BDRV_O_RDWR;
+ break;
+
+ case BLOCKDEV_CHANGE_READ_ONLY_MODE_RO:
+ bdrv_flags = 0;
+ break;
+
+ case BLOCKDEV_CHANGE_READ_ONLY_MODE_RW:
+ bdrv_flags = BDRV_O_RDWR;
+ break;
+
+ default:
+ abort();
+ }
+
bdrv_flags |= bdrv_is_snapshot(bs) ? BDRV_O_SNAPSHOT : 0;
qmp_bdrv_open_encrypted(bs, filename, bdrv_flags, drv, NULL, errp);
diff --git a/hmp.c b/hmp.c
index ef5e8bd..840da5c 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1189,7 +1189,7 @@ void hmp_change(Monitor *mon, const QDict *qdict)
}
qmp_change("vnc", target, !!arg, arg, &err);
} else {
- qmp_blockdev_change_medium(device, target, !!arg, arg, &err);
+ qmp_blockdev_change_medium(device, target, !!arg, arg, false, 0, &err);
if (err &&
error_get_class(err) == ERROR_CLASS_DEVICE_ENCRYPTED) {
error_free(err);
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 431517d..f58f446 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1662,6 +1662,24 @@
##
+# @BlockdevChangeReadOnlyMode:
+#
+# Specifies the new read-only mode of a block device subject to the
+# @blockdev-change-medium command.
+#
+# @retain: Retains the current read-only mode
+#
+# @ro: Makes the device read-only
+#
+# @rw: Makes the device writable
+#
+# Since: 2.3
+##
+{ 'enum': 'BlockdevChangeReadOnlyMode',
+ 'data': ['retain', 'ro', 'rw'] }
+
+
+##
# @blockdev-change-medium:
#
# Changes the medium inserted into a block device by ejecting the current
medium
@@ -1674,12 +1692,16 @@
# @format: #optional, format to open the new image with (defaults to the
# probed format)
#
+# @read-only: #optional, change the read-only mode of the device; defaults to
+# 'retain'
+#
# Since: 2.3
##
{ 'command': 'blockdev-change-medium',
'data': { 'device': 'str',
'filename': 'str',
- '*format': 'str' } }
+ '*format': 'str',
+ '*read-only': 'BlockdevChangeReadOnlyMode' } }
##
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 3f1f2eb..325db61 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -3647,7 +3647,7 @@ EQMP
{
.name = "blockdev-change-medium",
- .args_type = "device:B,filename:F,format:s?",
+ .args_type = "device:B,filename:F,format:s?,read-only:s?",
.mhandler.cmd_new = qmp_marshal_input_blockdev_change_medium,
},
@@ -3663,6 +3663,8 @@ Arguments:
- "device": device name (json-string)
- "filename": filename of the new image (json-string)
- "format": format of the new image (json-string, optional)
+- "read-only": new read-only mode (json-string, optional)
+ - Possible values: "retain" (default), "ro", "rw"
Examples:
@@ -3674,6 +3676,26 @@ Examples:
"format": "raw" } }
<- { "return": {} }
+2. Load a read-only medium into a writable drive
+
+-> { "execute": "blockdev-change-medium",
+ "arguments": { "device": "isa-fd0",
+ "filename": "/srv/images/ro.img",
+ "format": "raw",
+ "read-only": "retain" } }
+
+<- { "error":
+ { "class": "GenericError",
+ "desc": "Could not open '/srv/images/ro.img': Permission denied" } }
+
+-> { "execute": "blockdev-change-medium",
+ "arguments": { "device": "isa-fd0",
+ "filename": "/srv/images/ro.img",
+ "format": "raw",
+ "read-only": "ro" } }
+
+<- { "return": {} }
+
EQMP
{
diff --git a/qmp.c b/qmp.c
index 59fc6f7..febc1f6 100644
--- a/qmp.c
+++ b/qmp.c
@@ -402,7 +402,8 @@ void qmp_change(const char *device, const char *target,
if (strcmp(device, "vnc") == 0) {
qmp_change_vnc(target, has_arg, arg, errp);
} else {
- qmp_blockdev_change_medium(device, target, has_arg, arg, errp);
+ qmp_blockdev_change_medium(device, target, has_arg, arg, false, 0,
+ errp);
}
}
--
1.9.3
