[libvirt] [PATCHv6 9/8] blockjob: allow speed setting in block copy

[Eric Blake]

Similar to the recent race fix for 'block-stream', it is possible
to set the speed of a block copy job up front thanks to an optional
'speed' parameter to 'drive-mirror'.

* src/qemu/qemu_monitor_json.c (qemuMonitorJSONDriveMirror): Set
speed at job start.
* src/qemu/qemu_monitor_json.h (qemuMonitorJSONDriveMirror): Add
parameter.
* src/qemu/qemu_monitor.h (qemuMonitorDriveMirror): Likewise.
* src/qemu/qemu_driver.c (qemuDomainBlockCopy): Adjust caller.
* src/qemu/qemu_monitor.c (qemuMonitorDriveMirror): Likewise.
---

v6: new patch.  I haven't actually seen a qemu patch implementing this
yet, but it is a logical extension of the recent block-stream patch.

 src/qemu/qemu_driver.c       |    3 ++-
 src/qemu/qemu_monitor.c      |   22 +++++++++++++++++-----
 src/qemu/qemu_monitor.h      |    1 +
 src/qemu/qemu_monitor_json.c |    5 ++++-
 src/qemu/qemu_monitor_json.h |    1 +
 5 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 3a9e2d0..994393a 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -12108,7 +12108,8 @@ qemuDomainBlockCopy(virDomainPtr dom, const char *path,

     /* Actually start the mirroring */
     qemuDomainObjEnterMonitorWithDriver(driver, vm);
-    ret = qemuMonitorDriveMirror(priv->mon, device, dest, format, flags);
+    ret = qemuMonitorDriveMirror(priv->mon, device, dest, format, bandwidth,
+                                 flags);
     virDomainAuditDisk(vm, NULL, dest, "mirror", ret >= 0);
     qemuDomainObjExitMonitorWithDriver(driver, vm);
     if (ret < 0) {
diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
index fc84146..0c2ab48 100644
--- a/src/qemu/qemu_monitor.c
+++ b/src/qemu/qemu_monitor.c
@@ -2685,19 +2685,31 @@ qemuMonitorDiskSnapshot(qemuMonitorPtr mon, virJSONValuePtr actions,
     return ret;
 }

-/* Start a drive-mirror block job.  */
+/* Start a drive-mirror block job.  bandwidth is in MB/sec. */
 int
 qemuMonitorDriveMirror(qemuMonitorPtr mon,
                        const char *device, const char *file,
-                       const char *format, unsigned int flags)
+                       const char *format, unsigned long bandwidth,
+                       unsigned int flags)
 {
     int ret = -1;
+    unsigned long long speed;
+
+    VIR_DEBUG("mon=%p, device=%s, file=%s, format=%s, bandwidth=%luM, flags=%x",
+              mon, device, file, NULLSTR(format), bandwidth, flags);

-    VIR_DEBUG("mon=%p, device=%s, file=%s, format=%s, flags=%x",
-              mon, device, file, NULLSTR(format), flags);
+    /* Convert bandwidth MiB to bytes */
+    if (bandwidth > ULLONG_MAX / 1024 / 1024) {
+        qemuReportError(VIR_ERR_OVERFLOW,
+                        _("bandwidth must be less than %llu"),
+                        ULLONG_MAX / 1024 / 1024);
+        return -1;
+    }
+    speed = bandwidth * 1024ULL * 1024ULL;

     if (mon->json)
-        ret = qemuMonitorJSONDriveMirror(mon, device, file, format, flags);
+        ret = qemuMonitorJSONDriveMirror(mon, device, file, format, speed,
+                                         flags);
     else
         qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
                         _("drive-mirror requires JSON monitor"));
diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h
index 9ff8578..9dd0302 100644
--- a/src/qemu/qemu_monitor.h
+++ b/src/qemu/qemu_monitor.h
@@ -514,6 +514,7 @@ int qemuMonitorDriveMirror(qemuMonitorPtr mon,
                            const char *device,
                            const char *file,
                            const char *format,
+                           unsigned long bandwidth,
                            unsigned int flags)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3);
 int qemuMonitorDriveReopen(qemuMonitorPtr mon,
diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index 7b459ff..51b19cd 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -3204,10 +3204,12 @@ cleanup:
     return ret;
 }

+/* speed is in bytes/sec */
 int
 qemuMonitorJSONDriveMirror(qemuMonitorPtr mon,
                            const char *device, const char *file,
-                           const char *format, unsigned int flags)
+                           const char *format, unsigned long long speed,
+                           unsigned int flags)
 {
     int ret = -1;
     virJSONValuePtr cmd;
@@ -3219,6 +3221,7 @@ qemuMonitorJSONDriveMirror(qemuMonitorPtr mon,
                                      "s:device", device,
                                      "s:target", file,
                                      "b:full", !shallow,
+                                     "U:speed", speed,
                                      "s:mode",
                                      reuse ? "existing" : "absolute-paths",
                                      format ? "s:format" : NULL, format,
diff --git a/src/qemu/qemu_monitor_json.h b/src/qemu/qemu_monitor_json.h
index 71bd2cf..5371384 100644
--- a/src/qemu/qemu_monitor_json.h
+++ b/src/qemu/qemu_monitor_json.h
@@ -239,6 +239,7 @@ int qemuMonitorJSONDriveMirror(qemuMonitorPtr mon,
                                const char *device,
                                const char *file,
                                const char *format,
+                               unsigned long long speed,
                                unsigned int flags)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3);
 int qemuMonitorJSONDriveReopen(qemuMonitorPtr mon,
-- 
1.7.7.6