[PATCH 6/8] qemu: Check if the shared disk's cdbfilter conflicts with others

[Osier Yang <jyang@xxxxxxxxxx>]

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".

---
This assumes the lock manager will prevents one using same disk
mixed with non-shared and shared modes. I.E. The following
scenario won't be happen:

 * dom1, with disk /dev/sdb's cdbfilter="no" shared
 * dom2, with disk /dev/sdb's cdbfilter="yes" and non-shared

Without the lock manager, dom2's staring will override the
disk's unpriv_sgio to 0.

---
 src/qemu/qemu_process.c |   51 +++++++++++++++++++++++++++++++++++++++++++++++
 src/qemu/qemu_process.h |    2 +
 2 files changed, 53 insertions(+), 0 deletions(-)

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 4117251..ace0404 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -3385,6 +3385,54 @@ 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). Currently only checks the cdbfilter
+ * setting.
+ *
+ * Returns 0 if no conflicts, otherwise returns -1.
+ */
+int
+qemuCheckSharedDisk(virHashTablePtr sharedDisks,
+                    virDomainDiskDefPtr disk)
+{
+    int val;
+    size_t *ref = NULL;
+    char *key = NULL;
+    int ret = 0;
+
+    if (!(key = qemuGetSharedDiskKey(disk->src)))
+        return -1;
+
+    /* It can't be conflict if no other domain is
+     * is sharing it.
+     */
+    if (!(ref = virHashLookup(sharedDisks, key)))
+        goto cleanup;
+
+    if (ref == (void *)0x1)
+        goto cleanup;
+
+    if (virGetDeviceUnprivSGIO(disk->src, &val) < 0) {
+        ret = -1;
+        goto cleanup;
+    }
+
+    if ((val == 0 &&
+         disk->cdbfilter == VIR_DOMAIN_DISK_CDB_FILTER_YES) ||
+        (val == 1 &&
+         disk->cdbfilter == VIR_DOMAIN_DISK_CDB_FILTER_NO))
+        goto cleanup;
+
+    virReportError(VIR_ERR_INTERNAL_ERROR,
+                   _("cdbfilter of shared disk '%s' conflicts with other "
+                     "active domains"), disk->src);
+    ret = -1;
+
+cleanup:
+    VIR_FREE(key);
+    return ret;
+}
+
 int qemuProcessStart(virConnectPtr conn,
                      virQEMUDriverPtr driver,
                      virDomainObjPtr vm,
@@ -3733,6 +3781,9 @@ int qemuProcessStart(virConnectPtr conn,
         if (disk->type == VIR_DOMAIN_DISK_TYPE_BLOCK && disk->shared) {
             if (qemuAddSharedDisk(driver->sharedDisks, disk->src) < 0)
                 goto cleanup;
+
+            if (qemuCheckSharedDisk(driver->sharedDisks, disk) < 0)
+                goto cleanup;
         }
 
         /* Set sysfs unpriv_sgio if cdbfilter is specified */
diff --git a/src/qemu/qemu_process.h b/src/qemu/qemu_process.h
index c12df32..3aad08f 100644
--- a/src/qemu/qemu_process.h
+++ b/src/qemu/qemu_process.h
@@ -98,5 +98,7 @@ bool qemuProcessAutoDestroyActive(virQEMUDriverPtr driver,
                                   virDomainObjPtr vm);
 virBitmapPtr qemuPrepareCpumap(virQEMUDriverPtr driver,
                                virBitmapPtr nodemask);
+int qemuCheckSharedDisk(virHashTablePtr sharedDisks,
+                        virDomainDiskDefPtr disk);
 
 #endif /* __QEMU_PROCESS_H__ */
-- 
1.7.7.6

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