conf: backup: Allow configuration of names exported via NBD

If users wish to use different name for exported disks or bitmaps
the new fields allow to do so. Additionally they also document the
current settings.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

docs/formatbackup.html.in

@@ -85,6 +85,15 @@
               <dd>Setting this attribute to <code>yes</code>(default) specifies
                 that the disk should take part in the backup and using
                 <code>no</code> excludes the disk from the backup.</dd>
+              <dt><code>exportname</code></dt>
+              <dd>Allows modification of the NBD export name for the given disk.
+                By default equal to disk target.
+                Valid only for pull mode backups.</dd>
+              <dt><code>exportbitmap</code></dt>
+              <dd>Allows modification of the name of the bitmap describing dirty
+                blocks for an incremental backup exported via NBD export name
+                for the given disk.
+                Valid only for pull mode backups.</dd>
               <dt><code>type</code></dt>
               <dd>A mandatory attribute to describe the type of the
                 disk, except when <code>backup='no'</code> is

docs/schemas/domainbackup.rng

@@ -165,6 +165,14 @@
             <attribute name='name'>
               <ref name='diskTarget'/>
             </attribute>
+            <optional>
+              <attribute name='exportname'>
+                <text/>
+              </attribute>
+              <attribute name='exportbitmap'>
+                <text/>
+              </attribute>
+            </optional>
             <choice>
               <group>
                 <attribute name='backup'>

src/conf/backup_conf.c

@@ -71,6 +71,8 @@ virDomainBackupDefFree(virDomainBackupDefPtr def)
         virDomainBackupDiskDefPtr disk = def->disks + i;
 
         g_free(disk->name);
+        g_free(disk->exportname);
+        g_free(disk->exportbitmap);
         virObjectUnref(disk->store);
     }
 
@@ -124,6 +126,11 @@ virDomainBackupDiskDefParseXML(xmlNodePtr node,
     if (def->backup == VIR_TRISTATE_BOOL_NO)
         return 0;
 
+    if (!push) {
+        def->exportname = virXMLPropString(node, "exportname");
+        def->exportbitmap = virXMLPropString(node, "exportbitmap");
+    }
+
     if (internal) {
         if (!(state = virXMLPropString(node, "state")) ||
             (tmp = virDomainBackupDiskStateTypeFromString(state)) < 0) {
@@ -333,6 +340,9 @@ virDomainBackupDiskDefFormat(virBufferPtr buf,
     if (disk->backup == VIR_TRISTATE_BOOL_YES) {
         virBufferAsprintf(&attrBuf, " type='%s'", virStorageTypeToString(disk->store->type));
 
+        virBufferEscapeString(&attrBuf, " exportname='%s'", disk->exportname);
+        virBufferEscapeString(&attrBuf, " exportbitmap='%s'", disk->exportbitmap);
+
         if (disk->store->format > 0)
             virBufferEscapeString(&childBuf, "<driver type='%s'/>\n",
                                   virStorageFileFormatTypeToString(disk->store->format));

src/conf/backup_conf.h

@@ -51,6 +51,8 @@ typedef virDomainBackupDiskDef *virDomainBackupDiskDefPtr;
 struct _virDomainBackupDiskDef {
     char *name;     /* name matching the <target dev='...' of the domain */
     virTristateBool backup; /* whether backup is requested */
+    char *exportname; /* name of the NBD export for pull mode backup */
+    char *exportbitmap; /* name of the bitmap exposed in NBD for pull mode backup */
 
     /* details of target for push-mode, or of the scratch file for pull-mode */
     virStorageSourcePtr store;

tests/domainbackupxml2xmlin/backup-pull-seclabel.xml

@@ -2,7 +2,7 @@
   <incremental>1525889631</incremental>
   <server transport='tcp' name='localhost' port='10809'/>
   <disks>
-    <disk name='vda' type='file'>
+    <disk name='vda' type='file' exportname='test-vda' exportbitmap='blah'>
       <driver type='qcow2'/>
       <scratch file='/path/to/file'>
         <seclabel model='dac' relabel='no'/>

tests/domainbackupxml2xmlout/backup-pull-seclabel.xml

@@ -2,7 +2,7 @@
   <incremental>1525889631</incremental>
   <server transport='tcp' name='localhost' port='10809'/>
   <disks>
-    <disk name='vda' backup='yes' type='file'>
+    <disk name='vda' backup='yes' type='file' exportname='test-vda' exportbitmap='blah'>
       <driver type='qcow2'/>
       <scratch file='/path/to/file'>
         <seclabel model='dac' relabel='no'/>