[libvirt] [PATCHv6 5/7] lib: Introduce flag VIR_DOMAIN_BLOCK_REBASE_RELATIVE

[Peter Krempa]

Introduce flag for the block rebase API to allow the rebase operation to
leave the chain relatively addressed. Also adds a virsh switch to enable
this behavior.
---
 include/libvirt/libvirt.h.in |  3 +++
 src/libvirt.c                |  3 +++
 tools/virsh-domain.c         | 12 ++++++++++--
 tools/virsh.pod              |  4 ++++
 4 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in
index d6a4a0f..d438251 100644
--- a/include/libvirt/libvirt.h.in
+++ b/include/libvirt/libvirt.h.in
@@ -2580,6 +2580,9 @@ typedef enum {
                                                    file for a copy */
     VIR_DOMAIN_BLOCK_REBASE_COPY_RAW  = 1 << 2, /* Make destination file raw */
     VIR_DOMAIN_BLOCK_REBASE_COPY      = 1 << 3, /* Start a copy job */
+    VIR_DOMAIN_BLOCK_REBASE_RELATIVE  = 1 << 4, /* Keep backing chain
+                                                   referenced using relative
+                                                   names */
 } virDomainBlockRebaseFlags;

 int           virDomainBlockRebase(virDomainPtr dom, const char *disk,
diff --git a/src/libvirt.c b/src/libvirt.c
index 5c19ec9..307de2a 100644
--- a/src/libvirt.c
+++ b/src/libvirt.c
@@ -19721,6 +19721,9 @@ virDomainBlockPull(virDomainPtr dom, const char *disk,
  * exists.  If the job is aborted, a new one can be started later to
  * resume from the same point.
  *
+ * If @flags contains VIR_DOMAIN_BLOCK_REBASE_RELATIVE, the name recorded
+ * into the active disk as the location for @base will be kept relative.
+ *
  * When @flags includes VIR_DOMAIN_BLOCK_REBASE_COPY, this starts a copy,
  * where @base must be the name of a new file to copy the chain to.  By
  * default, the copy will pull the entire source chain into the destination
diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c
index b825a05..8275755 100644
--- a/tools/virsh-domain.c
+++ b/tools/virsh-domain.c
@@ -1479,10 +1479,14 @@ blockJobImpl(vshControl *ctl, const vshCmd *cmd,
     case VSH_CMD_BLOCK_JOB_PULL:
         if (vshCommandOptStringReq(ctl, cmd, "base", &base) < 0)
             goto cleanup;
-        if (base)
-            ret = virDomainBlockRebase(dom, path, base, bandwidth, 0);
+      if (vshCommandOptBool(cmd, "keep-relative"))
+          flags |= VIR_DOMAIN_BLOCK_REBASE_RELATIVE;
+
+        if (base || flags)
+            ret = virDomainBlockRebase(dom, path, base, bandwidth, flags);
         else
             ret = virDomainBlockPull(dom, path, bandwidth, 0);
+
         break;
     case VSH_CMD_BLOCK_JOB_COMMIT:
         if (vshCommandOptStringReq(ctl, cmd, "base", &base) < 0 ||
@@ -2118,6 +2122,10 @@ static const vshCmdOptDef opts_block_pull[] = {
      .type = VSH_OT_BOOL,
      .help = N_("with --wait, don't wait for cancel to finish")
     },
+    {.name = "keep-relative",
+     .type = VSH_OT_BOOL,
+     .help = N_("keep the backing chain relatively referenced")
+    },
     {.name = NULL}
 };

diff --git a/tools/virsh.pod b/tools/virsh.pod
index 1fe359c..949cf57 100644
--- a/tools/virsh.pod
+++ b/tools/virsh.pod
@@ -876,6 +876,7 @@ I<bandwidth> specifies copying bandwidth limit in MiB/s.

 =item B<blockpull> I<domain> I<path> [I<bandwidth>] [I<base>]
 [I<--wait> [I<--verbose>] [I<--timeout> B<seconds>] [I<--async>]]
+[I<--keep-relative>]

 Populate a disk from its backing image chain. By default, this command
 flattens the entire chain; but if I<base> is specified, containing the
@@ -895,6 +896,9 @@ is triggered, I<--async> will return control to the user as fast as
 possible, otherwise the command may continue to block a little while
 longer until the job is done cleaning up.

+Using the I<--keep-relative> flag will keep the backing chain names
+relative.
+
 I<path> specifies fully-qualified path of the disk; it corresponds
 to a unique target name (<target dev='name'/>) or source file (<source
 file='name'/>) for one of the disk devices attached to I<domain> (see
-- 
1.9.3