blockdev: read-only-mode for blockdev-change-medium

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 <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/blockdev.c b/blockdev.c
index b3a958c4aa..34f6e5bbb0 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2145,6 +2145,8 @@ void qmp_blockdev_insert_medium(const char *device, const char *node_name,
 
 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;
@@ -2166,6 +2168,26 @@ void qmp_blockdev_change_medium(const char *device, const char *filename,
 
     bdrv_flags = blk_get_open_flags_from_root_state(blk);
 
+    if (!has_read_only) {
+        read_only = BLOCKDEV_CHANGE_READ_ONLY_MODE_RETAIN;
+    }
+
+    switch (read_only) {
+    case BLOCKDEV_CHANGE_READ_ONLY_MODE_RETAIN:
+        break;
+
+    case BLOCKDEV_CHANGE_READ_ONLY_MODE_READ_ONLY:
+        bdrv_flags &= ~BDRV_O_RDWR;
+        break;
+
+    case BLOCKDEV_CHANGE_READ_ONLY_MODE_READ_WRITE:
+        bdrv_flags |= BDRV_O_RDWR;
+        break;
+
+    default:
+        abort();
+    }
+
     if (has_format) {
         options = qdict_new();
         qdict_put(options, "driver", qstring_from_str(format));