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From 736bcac80123ee6415953277449359722ae93d37 Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Wed, 10 Oct 2018 13:50:54 +0100
Subject: [PATCH 4/5] commit: Add top-node/base-node options

RH-Author: Kevin Wolf <kwolf@redhat.com>
Message-id: <20181010135055.3874-2-kwolf@redhat.com>
Patchwork-id: 82569
O-Subject: [RHEL-8 qemu-kvm PATCH 1/2] commit: Add top-node/base-node options
Bugzilla: 1637970
RH-Acked-by: John Snow <jsnow@redhat.com>
RH-Acked-by: Fam Zheng <famz@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

The block-commit QMP command required specifying the top and base nodes
of the commit jobs using the file name of that node. While this works
in simple cases (local files with absolute paths), the file names
generated for more complicated setups can be hard to predict.

The block-commit command has more problems than just this, so we want to
replace it altogether in the long run, but libvirt needs a reliable way
to address nodes now. So we don't want to wait for a new, cleaner
command, but just add the minimal thing needed right now.

This adds two new options top-node and base-node to the command, which
allow specifying node names instead. They are mutually exclusive with
the old options.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 3c605f4074ebeb97970eb660fb56a9cb06525923)
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 blockdev.c           | 32 ++++++++++++++++++++++++++++++--
 qapi/block-core.json | 24 ++++++++++++++++++------
 2 files changed, 48 insertions(+), 8 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index b8e4b0d..70af034 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3325,7 +3325,9 @@ out:
 }
 
 void qmp_block_commit(bool has_job_id, const char *job_id, const char *device,
+                      bool has_base_node, const char *base_node,
                       bool has_base, const char *base,
+                      bool has_top_node, const char *top_node,
                       bool has_top, const char *top,
                       bool has_backing_file, const char *backing_file,
                       bool has_speed, int64_t speed,
@@ -3386,7 +3388,20 @@ void qmp_block_commit(bool has_job_id, const char *job_id, const char *device,
     /* default top_bs is the active layer */
     top_bs = bs;
 
-    if (has_top && top) {
+    if (has_top_node && has_top) {
+        error_setg(errp, "'top-node' and 'top' are mutually exclusive");
+        goto out;
+    } else if (has_top_node) {
+        top_bs = bdrv_lookup_bs(NULL, top_node, errp);
+        if (top_bs == NULL) {
+            goto out;
+        }
+        if (!bdrv_chain_contains(bs, top_bs)) {
+            error_setg(errp, "'%s' is not in this backing file chain",
+                       top_node);
+            goto out;
+        }
+    } else if (has_top && top) {
         if (strcmp(bs->filename, top) != 0) {
             top_bs = bdrv_find_backing_image(bs, top);
         }
@@ -3399,7 +3414,20 @@ void qmp_block_commit(bool has_job_id, const char *job_id, const char *device,
 
     assert(bdrv_get_aio_context(top_bs) == aio_context);
 
-    if (has_base && base) {
+    if (has_base_node && has_base) {
+        error_setg(errp, "'base-node' and 'base' are mutually exclusive");
+        goto out;
+    } else if (has_base_node) {
+        base_bs = bdrv_lookup_bs(NULL, base_node, errp);
+        if (base_bs == NULL) {
+            goto out;
+        }
+        if (!bdrv_chain_contains(top_bs, base_bs)) {
+            error_setg(errp, "'%s' is not in this backing file chain",
+                       base_node);
+            goto out;
+        }
+    } else if (has_base && base) {
         base_bs = bdrv_find_backing_image(top_bs, base);
     } else {
         base_bs = bdrv_find_base(top_bs);
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 602c028..5fb7983 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1434,12 +1434,23 @@
 #
 # @device:  the device name or node-name of a root node
 #
-# @base:   The file name of the backing image to write data into.
-#                    If not specified, this is the deepest backing image.
+# @base-node: The node name of the backing image to write data into.
+#             If not specified, this is the deepest backing image.
+#             (since: 3.1)
 #
-# @top:    The file name of the backing image within the image chain,
-#                    which contains the topmost data to be committed down. If
-#                    not specified, this is the active layer.
+# @base: Same as @base-node, except that it is a file name rather than a node
+#        name. This must be the exact filename string that was used to open the
+#        node; other strings, even if addressing the same file, are not
+#        accepted (deprecated, use @base-node instead)
+#
+# @top-node: The node name of the backing image within the image chain
+#            which contains the topmost data to be committed down. If
+#            not specified, this is the active layer. (since: 3.1)
+#
+# @top: Same as @top-node, except that it is a file name rather than a node
+#       name. This must be the exact filename string that was used to open the
+#       node; other strings, even if addressing the same file, are not
+#       accepted (deprecated, use @base-node instead)
 #
 # @backing-file:  The backing file string to write into the overlay
 #                           image of 'top'.  If 'top' is the active layer,
@@ -1508,7 +1519,8 @@
 #
 ##
 { 'command': 'block-commit',
-  'data': { '*job-id': 'str', 'device': 'str', '*base': 'str', '*top': 'str',
+  'data': { '*job-id': 'str', 'device': 'str', '*base-node': 'str',
+            '*base': 'str', '*top-node': 'str', '*top': 'str',
             '*backing-file': 'str', '*speed': 'int',
             '*filter-node-name': 'str',
             '*auto-finalize': 'bool', '*auto-dismiss': 'bool' } }
-- 
1.8.3.1