[libvirt] [PATCH 07/12] qemu: Error out when domain starting if the cdbfilter setting conflicts

[Osier Yang]

This prevents the domain starting if the shared disk's setting
conflicts with other active domain(s), E.g. A domain with
"cdbfilter" set as "yes", however, another active domain is using
it set as "no".
---
 src/qemu/qemu_process.c |   44 ++++++++++++++++++++++++++++++++++++++++++++
 src/qemu/qemu_process.h |    3 +++
 2 files changed, 47 insertions(+), 0 deletions(-)

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index f39b83f..ba777e2 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -3380,6 +3380,42 @@ qemuProcessReconnectAll(virConnectPtr conn, virQEMUDriverPtr driver)
     virHashForEach(driver->domains.objs, qemuProcessReconnectHelper, &data);
 }
 
+/* Check if a shared disk's setting conflicts with the conf
+ * used by other domain(s).
+ *
+ * Returns 0 if no conflicts, otherwise returns -1.
+ */
+int
+qemuCheckSharedDisk(virHashTablePtr sharedDisks,
+                    virDomainDiskDefPtr disk)
+{
+    int val;
+    qemuSharedDiskEntryPtr entry = NULL;
+
+    /* It can't be conflict if no other domain is
+     * is sharing it.
+     */
+    if (!(entry = virHashLookup(sharedDisks, disk->src)))
+        return 0;
+
+    if (entry->ref == 1)
+        return 0;
+
+    if (virGetDeviceUnprivSGIO(disk->src, &val) < 0)
+        return -1;
+
+    if ((val == 0 &&
+         disk->orig_cdbfilter == VIR_DOMAIN_DISK_CDB_FILTER_YES) ||
+        (val == 1 &&
+         disk->orig_cdbfilter == VIR_DOMAIN_DISK_CDB_FILTER_NO))
+        return 0;
+
+    virReportError(VIR_ERR_INTERNAL_ERROR,
+                   _("cdbfilter of shared disk '%s' conflicts with other "
+                     "active domains"), disk->src);
+    return -1;
+}
+
 int qemuProcessStart(virConnectPtr conn,
                      virQEMUDriverPtr driver,
                      virDomainObjPtr vm,
@@ -3730,9 +3766,17 @@ int qemuProcessStart(virConnectPtr conn,
         }
 
         if (disk->shared) {
+            /* qemuAddSharedDisk must be called before qemuCheckSharedDisk
+             * in case of qemuCheckSharedDisk fails and qemuProcessStop
+             * will restore the disk's unpriv_sgio if there is only
+             * one domain is using the shared disk.
+             */
             if (qemuAddSharedDisk(driver->sharedDisks, disk->src,
                                   disk->orig_cdbfilter) < 0)
                 goto cleanup;
+
+            if (qemuCheckSharedDisk(driver->sharedDisks, disk) < 0)
+                goto cleanup;
         }
     }
 
diff --git a/src/qemu/qemu_process.h b/src/qemu/qemu_process.h
index c12df32..6d92368 100644
--- a/src/qemu/qemu_process.h
+++ b/src/qemu/qemu_process.h
@@ -99,4 +99,7 @@ bool qemuProcessAutoDestroyActive(virQEMUDriverPtr driver,
 virBitmapPtr qemuPrepareCpumap(virQEMUDriverPtr driver,
                                virBitmapPtr nodemask);
 
+int qemuCheckSharedDisk(virHashTablePtr sharedDisks,
+                        virDomainDiskDefPtr disk);
+
 #endif /* __QEMU_PROCESS_H__ */
-- 
1.7.7.6