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[Qemu-block] [PATCH v2 6/6] block: Deprecate "backing": ""
From: |
Max Reitz |
Subject: |
[Qemu-block] [PATCH v2 6/6] block: Deprecate "backing": "" |
Date: |
Sat, 20 Jan 2018 16:44:12 +0100 |
We have a clear replacement, so let's deprecate it.
Signed-off-by: Max Reitz <address@hidden>
---
qapi/block-core.json | 4 ++--
block.c | 4 ++++
qemu-doc.texi | 7 +++++++
qemu-options.hx | 4 ++--
4 files changed, 15 insertions(+), 4 deletions(-)
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 89ed2bc6a4..78de8eff63 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1090,7 +1090,7 @@
# @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
##
@@ -1238,7 +1238,7 @@
# "node-name": "node1534",
# "file": { "driver": "file",
# "filename": "hd1.qcow2" },
-# "backing": "" } }
+# "backing": null } }
#
# <- { "return": {} }
#
diff --git a/block.c b/block.c
index 32b7887651..5ac0aba638 100644
--- a/block.c
+++ b/block.c
@@ -2600,6 +2600,10 @@ static BlockDriverState *bdrv_open_inherit(const char
*filename,
if (qobject_to(qdict_get(options, "backing"), QNull) != 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");
}
diff --git a/qemu-doc.texi b/qemu-doc.texi
index 3e9eb819a6..d321908da8 100644
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -2773,6 +2773,13 @@ or ``ivshmem-doorbell`` device types.
The ``xlnx-ep108'' machine has been replaced by the ``xlnx-zcu102'' machine.
The ``xlnx-zcu102'' machine has the same features and capabilites in QEMU.
address@hidden Block device options
+
address@hidden "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
diff --git a/qemu-options.hx b/qemu-options.hx
index 5ff741a4af..76e9a5b06b 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -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
--
2.14.3
- Re: [Qemu-block] [PATCH v2 1/6] qapi: Add qobject_to(), (continued)
- [Qemu-block] [PATCH v2 3/6] qapi: Remove qobject_to_X() functions, Max Reitz, 2018/01/20
- [Qemu-block] [PATCH v2 4/6] qapi: Make more of qobject_to(), Max Reitz, 2018/01/20
- [Qemu-block] [PATCH v2 2/6] qapi: Replace qobject_to_X(o) by qobject_to(o, X), Max Reitz, 2018/01/20
- [Qemu-block] [PATCH v2 5/6] block: Handle null backing link, Max Reitz, 2018/01/20
- [Qemu-block] [PATCH v2 6/6] block: Deprecate "backing": "",
Max Reitz <=