block rebase: initial qemu implementation

This is a trivial implementation, which works with the current
released qemu 1.0 with backports of preliminary block pull but
no partial rebase.  Future patches will update the monitor handling
to support an optional parameter for partial rebase; but as qemu
1.1 is unreleased, it can be in later patches, designed to be
backported on top of the supported API.

* src/qemu/qemu_driver.c (qemuDomainBlockJobImpl): Add parameter,
and adjust callers.  Drop redundant check.
(qemuDomainBlockPull): Move guts...
(qemuDomainBlockRebase): ...to new function.

src/qemu/qemu_driver.c

@@ -11296,7 +11296,7 @@ cleanup:
 }
 
 static int
-qemuDomainBlockJobImpl(virDomainPtr dom, const char *path,
+qemuDomainBlockJobImpl(virDomainPtr dom, const char *path, const char *base,
                        unsigned long bandwidth, virDomainBlockJobInfoPtr info,
                        int mode)
 {
@@ -11316,16 +11316,18 @@ qemuDomainBlockJobImpl(virDomainPtr dom, const char *path,
         goto cleanup;
     }
 
-    if (!virDomainObjIsActive(vm)) {
-        qemuReportError(VIR_ERR_OPERATION_INVALID,
-                        "%s", _("domain is not running"));
-        goto cleanup;
-    }
-
     device = qemuDiskPathToAlias(vm, path);
     if (!device) {
         goto cleanup;
     }
+    /* XXX - add a qemu capability check; if qemu 1.1 or newer, then
+     *  validate and convert non-NULL base into something that can
+     * be passed as optional base argument.  */
+    if (base)  {
+        qemuReportError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s",
+                        _("partial block pull is not supported with this QEMU binary"));
+        goto cleanup;
+    }
 
     if (qemuDomainObjBeginJobWithDriver(driver, vm, QEMU_JOB_MODIFY) < 0)
         goto cleanup;
@@ -11359,7 +11361,7 @@ static int
 qemuDomainBlockJobAbort(virDomainPtr dom, const char *path, unsigned int flags)
 {
     virCheckFlags(0, -1);
-    return qemuDomainBlockJobImpl(dom, path, 0, NULL, BLOCK_JOB_ABORT);
+    return qemuDomainBlockJobImpl(dom, path, NULL, 0, NULL, BLOCK_JOB_ABORT);
 }
 
 static int
@@ -11367,7 +11369,7 @@ qemuDomainGetBlockJobInfo(virDomainPtr dom, const char *path,
                            virDomainBlockJobInfoPtr info, unsigned int flags)
 {
     virCheckFlags(0, -1);
-    return qemuDomainBlockJobImpl(dom, path, 0, info, BLOCK_JOB_INFO);
+    return qemuDomainBlockJobImpl(dom, path, NULL, 0, info, BLOCK_JOB_INFO);
 }
 
 static int
@@ -11375,23 +11377,32 @@ qemuDomainBlockJobSetSpeed(virDomainPtr dom, const char *path,
                            unsigned long bandwidth, unsigned int flags)
 {
     virCheckFlags(0, -1);
-    return qemuDomainBlockJobImpl(dom, path, bandwidth, NULL, BLOCK_JOB_SPEED);
+    return qemuDomainBlockJobImpl(dom, path, NULL, bandwidth, NULL,
+                                  BLOCK_JOB_SPEED);
 }
 
 static int
-qemuDomainBlockPull(virDomainPtr dom, const char *path, unsigned long bandwidth,
-                    unsigned int flags)
+qemuDomainBlockRebase(virDomainPtr dom, const char *path, const char *base,
+                      unsigned long bandwidth, unsigned int flags)
 {
     int ret;
 
     virCheckFlags(0, -1);
-    ret = qemuDomainBlockJobImpl(dom, path, bandwidth, NULL, BLOCK_JOB_PULL);
+    ret = qemuDomainBlockJobImpl(dom, path, base, bandwidth, NULL,
+                                 BLOCK_JOB_PULL);
     if (ret == 0 && bandwidth != 0)
-        ret = qemuDomainBlockJobImpl(dom, path, bandwidth, NULL,
+        ret = qemuDomainBlockJobImpl(dom, path, NULL, bandwidth, NULL,
                                      BLOCK_JOB_SPEED);
     return ret;
 }
 
+static int
+qemuDomainBlockPull(virDomainPtr dom, const char *path, unsigned long bandwidth,
+                    unsigned int flags)
+{
+    return qemuDomainBlockRebase(dom, path, NULL, bandwidth, flags);
+}
+
 static int
 qemuDomainOpenGraphics(virDomainPtr dom,
                        unsigned int idx,
@@ -12130,6 +12141,7 @@ static virDriver qemuDriver = {
     .domainGetBlockJobInfo = qemuDomainGetBlockJobInfo, /* 0.9.4 */
     .domainBlockJobSetSpeed = qemuDomainBlockJobSetSpeed, /* 0.9.4 */
     .domainBlockPull = qemuDomainBlockPull, /* 0.9.4 */
+    .domainBlockRebase = qemuDomainBlockRebase, /* 0.9.10 */
     .isAlive = qemuIsAlive, /* 0.9.8 */
     .nodeSuspendForDuration = nodeSuspendForDuration, /* 0.9.8 */
     .domainSetBlockIoTune = qemuDomainSetBlockIoTune, /* 0.9.8 */