[libvirt] [PATCH 08/12] getstats: add block.n.path stat

[Eric Blake]

I'm about to make block stats optionally more complex to cover
backing chains, where block.count will no longer equal the number
of <disks> for a domain.  For these reasons, it is nicer if the
statistics output includes the source path (for local files).
This patch doesn't add anything for network disks, although we
may decide to add that later.

With this patch, I now see the following for the same domain as
in earlier patches (one qcow2 file, and an empty cdrom drive):
$ virsh domstats --block foo
Domain: 'foo'
  block.count=2
  block.0.name=hda
  block.0.path=/var/lib/libvirt/images/foo.qcow2
  block.0.allocation=200704
  block.0.capacity=42949672960
  block.0.physical=200704
  block.1.name=hdc

* src/libvirt-domain.c (virConnectGetAllDomainStats): Document
new field.
* tools/virsh.pod (domstats): Document new field.
* src/qemu/qemu_driver.c (qemuDomainGetStatsBlock): Return the new
stat for local files/block devices.
(QEMU_ADD_NAME_PARAM): Add parameter.
(qemuDomainGetStatsInterface): Update caller.

Signed-off-by: Eric Blake <eblake at redhat.com>
---
 src/libvirt-domain.c   |  3 +++
 src/qemu/qemu_driver.c | 11 +++++++----
 tools/virsh.pod        |  2 ++
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
index 87123d1..cb76d8c 100644
--- a/src/libvirt-domain.c
+++ b/src/libvirt-domain.c
@@ -10910,6 +10910,9 @@ virConnectGetDomainCapabilities(virConnectPtr conn,
  * "block.<num>.name" - name of the block device <num> as string.
  *                      matches the target name (vda/sda/hda) of the
  *                      block device.
+ * "block.<num>.path" - string describing the source of block device <num>,
+ *                      if it is a file or block device (omitted for network
+ *                      sources and drives with no media inserted).
  * "block.<num>.rd.reqs" - number of read requests as unsigned long long.
  * "block.<num>.rd.bytes" - number of read bytes as unsigned long long.
  * "block.<num>.rd.times" - total time (ns) spent on reads as
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 723391b..5334f8d 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -18422,11 +18422,11 @@ do { \
         goto cleanup; \
 } while (0)

-#define QEMU_ADD_NAME_PARAM(record, maxparams, type, num, name) \
+#define QEMU_ADD_NAME_PARAM(record, maxparams, type, subtype, num, name) \
 do { \
     char param_name[VIR_TYPED_PARAM_FIELD_LENGTH]; \
     snprintf(param_name, VIR_TYPED_PARAM_FIELD_LENGTH, \
-             "%s.%zu.name", type, num); \
+             "%s.%zu.%s", type, num, subtype); \
     if (virTypedParamsAddString(&(record)->params, \
                                 &(record)->nparams, \
                                 maxparams, \
@@ -18471,7 +18471,7 @@ qemuDomainGetStatsInterface(virQEMUDriverPtr driver ATTRIBUTE_UNUSED,
         memset(&tmp, 0, sizeof(tmp));

         QEMU_ADD_NAME_PARAM(record, maxparams,
-                            "net", i, dom->def->nets[i]->ifname);
+                            "net", "name", i, dom->def->nets[i]->ifname);

         if (virNetInterfaceStats(dom->def->nets[i]->ifname, &tmp) < 0) {
             virResetLastError();
@@ -18564,7 +18564,10 @@ qemuDomainGetStatsBlock(virQEMUDriverPtr driver,
         qemuBlockStats *entry;
         virDomainDiskDefPtr disk = dom->def->disks[i];

-        QEMU_ADD_NAME_PARAM(record, maxparams, "block", i, disk->dst);
+        QEMU_ADD_NAME_PARAM(record, maxparams, "block", "name", i, disk->dst);
+        if (virStorageSourceIsLocalStorage(disk->src) && disk->src->path)
+            QEMU_ADD_NAME_PARAM(record, maxparams, "block", "path",
+                                i, disk->src->path);

         if (abbreviated || !disk->info.alias ||
             !(entry = virHashLookup(stats, disk->info.alias))) {
diff --git a/tools/virsh.pod b/tools/virsh.pod
index c070261..cbd82275 100644
--- a/tools/virsh.pod
+++ b/tools/virsh.pod
@@ -883,6 +883,8 @@ I<--interface> returns:
 I<--block> returns:
 "block.count" - number of block devices on this domain,
 "block.<num>.name" - name of the target of the block device <num>,
+"block.<num>.path" - file source of block device <num>, if it is a
+local file or block device,
 "block.<num>.rd.reqs" - number of read requests,
 "block.<num>.rd.bytes" - number of read bytes,
 "block.<num>.rd.times" - total time (ns) spent on reads,
-- 
1.9.3