Commit 4f7be280 authored by Max Reitz's avatar Max Reitz Committed by Eric Blake
Browse files

block: Deprecate "backing": "" 



We have a clear replacement, so let's deprecate it.

Signed-off-by: default avatarMax Reitz <mreitz@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Reviewed-by: default avatarAlberto Garcia <berto@igalia.com>
Message-Id: <20180224154033.29559-8-mreitz@redhat.com>
Signed-off-by: default avatarEric Blake <eblake@redhat.com>
parent e59a0cf1

block.c

+4 −0
Original line number Diff line number Diff line
@@ -2649,6 +2649,10 @@ static BlockDriverState *bdrv_open_inherit(const char *filename, 
    if (qobject_to(QNull, qdict_get(options, "backing")) != NULL ||

        (backing && *backing == '\0'))

    {

        if (backing) {

            warn_report("Use of \"backing\": \"\" is deprecated; "

                        "use \"backing\": null instead");

        }

        flags |= BDRV_O_NO_BACKING;

        qdict_del(options, "backing");

    }

qapi/block-core.json

+2 −2
Original line number Diff line number Diff line
@@ -1174,7 +1174,7 @@ 
# @overlay: reference to the existing block device that will become

#           the overlay of @node, as part of creating the snapshot.

#           It must not have a current backing file (this can be

#           achieved by passing "backing": "" to blockdev-add).

#           achieved by passing "backing": null to blockdev-add).

#

# Since: 2.5

##
@@ -1347,7 +1347,7 @@ 
#                     "node-name": "node1534",

#                     "file": { "driver": "file",

#                               "filename": "hd1.qcow2" },

#                     "backing": "" } }

#                     "backing": null } }

#

# <- { "return": {} }

#

qemu-doc.texi

+7 −0
Original line number Diff line number Diff line
@@ -2789,6 +2789,13 @@ support page sizes < 4096 any longer. 
The ``xlnx-ep108'' machine has been replaced by the ``xlnx-zcu102'' machine.

The ``xlnx-zcu102'' machine has the same features and capabilites in QEMU.



@section Block device options



@subsection "backing": "" (since 2.12.0)



In order to prevent QEMU from automatically opening an image's backing

chain, use ``"backing": null'' instead.



@node License

@appendix License

qemu-options.hx

+2 −2
Original line number Diff line number Diff line
@@ -743,8 +743,8 @@ Reference to or definition of the data source block driver node 


@item backing

Reference to or definition of the backing file block device (default is taken

from the image file). It is allowed to pass an empty string here in order to

disable the default backing file.

from the image file). It is allowed to pass @code{null} here in order to disable

the default backing file.



@item lazy-refcounts

Whether to enable the lazy refcounts feature (on/off; default is taken from the