Commit 39ff43d9 authored by Max Reitz's avatar Max Reitz Committed by Kevin Wolf
Browse files

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: default avatarMax Reitz <mreitz@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 10686749

blockdev.c

+22 −0
Original line number Diff line number Diff line
@@ -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));

hmp.c

+1 −1
Original line number Diff line number Diff line
@@ -1355,7 +1355,7 @@ 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);

qapi/block-core.json

+23 −1
Original line number Diff line number Diff line
@@ -1958,6 +1958,24 @@ 
            'node-name': 'str'} }





##

# @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

#

# @read-only:   Makes the device read-only

#

# @read-write:  Makes the device writable

#

# Since: 2.3

##

{ 'enum': 'BlockdevChangeReadOnlyMode',

  'data': ['retain', 'read-only', 'read-write'] }





##

# @blockdev-change-medium:

#
@@ -1973,12 +1991,16 @@ 
# @format:          #optional, format to open the new image with (defaults to

#                   the probed format)

#

# @read-only-mode:  #optional, change the read-only mode of the device; defaults

#                   to 'retain'

#

# Since: 2.5

##

{ 'command': 'blockdev-change-medium',

  'data': { 'device': 'str',

            'filename': 'str',

            '*format': 'str' } }

            '*format': 'str',

            '*read-only-mode': 'BlockdevChangeReadOnlyMode' } }





##

qmp-commands.hx

+23 −1
Original line number Diff line number Diff line
@@ -4183,7 +4183,7 @@ EQMP 


    {

        .name       = "blockdev-change-medium",

        .args_type  = "device:B,filename:F,format:s?",

        .args_type  = "device:B,filename:F,format:s?,read-only-mode:s?",

        .mhandler.cmd_new = qmp_marshal_blockdev_change_medium,

    },
@@ -4199,6 +4199,8 @@ 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-mode": new read-only mode (json-string, optional)

          - Possible values: "retain" (default), "read-only", "read-write"



Examples:
@@ -4210,6 +4212,26 @@ 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-mode": "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-mode": "read-only" } }



<- { "return": {} }



EQMP



    {

qmp.c

+2 −1
Original line number Diff line number Diff line
@@ -414,7 +414,8 @@ 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);

    }

}