qemu: driver: Improve error suppression in qemuDomainStorageUpdatePhysical

None of the callers of qemuDomainStorageUpdatePhysical care about
errors.

Use the new flag for qemuDomainStorageOpenStat which suppresses some
errors and move the reset of the rest of the uncommon errors into this
function. Document what is happening in a comment for the function.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

src/qemu/qemu_driver.c

@@ -12318,6 +12318,19 @@ qemuDomainStorageCloseStat(virStorageSourcePtr src,
 }
 
 
+/**
+ * qemuDomainStorageUpdatePhysical:
+ * @driver: qemu driver
+ * @cfg: qemu driver configuration object
+ * @vm: domain object
+ * @src: storage source to update
+ *
+ * Update the physical size of the disk by reading the actual size of the image
+ * on disk.
+ *
+ * Returns 0 on successful update and -1 otherwise (some uncommon errors may be
+ * reported but are reset (thus only logged)).
+ */
 static int
 qemuDomainStorageUpdatePhysical(virQEMUDriverPtr driver,
                                 virQEMUDriverConfigPtr cfg,
@@ -12331,8 +12344,11 @@ qemuDomainStorageUpdatePhysical(virQEMUDriverPtr driver,
     if (virStorageSourceIsEmpty(src))
         return 0;
 
-    if (qemuDomainStorageOpenStat(driver, cfg, vm, src, &fd, &sb, false) < 0)
+    if ((ret = qemuDomainStorageOpenStat(driver, cfg, vm, src, &fd, &sb, true)) <= 0) {
+        if (ret < 0)
+            virResetLastError();
         return -1;
+    }
 
     ret = virStorageSourceUpdatePhysicalSize(src, fd, &sb);
 
@@ -12504,7 +12520,6 @@ qemuDomainGetBlockInfo(virDomainPtr dom,
         if (qemuDomainStorageUpdatePhysical(driver, cfg, vm, disk->src) == 0) {
             info->physical = disk->src->physical;
         } else {
-            virResetLastError();
             info->physical = entry->physical;
         }
     } else {
@@ -21376,12 +21391,9 @@ qemuDomainGetStatsOneBlock(virQEMUDriverPtr driver,
         QEMU_ADD_BLOCK_PARAM_ULL(record, maxparams, block_idx,
                                  "physical", entry->physical);
     } else {
-        if (qemuDomainStorageUpdatePhysical(driver, cfg, dom, src) == 0) {
+        if (qemuDomainStorageUpdatePhysical(driver, cfg, dom, src) == 0)
             QEMU_ADD_BLOCK_PARAM_ULL(record, maxparams, block_idx,
                                      "physical", src->physical);
-        } else {
-            virResetLastError();
-        }
     }
 
     ret = 0;