From: Peter Krempa <pkrempa@redhat.com>
Date: Tue, 14 Nov 2017 15:34:46 +0100
Subject: [PATCH] qemu: block: Add function to check if storage source allows
 concurrent access

Storage source format backing a shared device (e.g. running a cluster
filesystem) needs to support the sharing so that metadata are not
corrupted. Add a central function for checking this.

(cherry picked from commit 1fc3cd8731640aefc48bbd9fc489f21cb99c6f67)
---
 src/qemu/qemu_block.c | 15 +++++++++++++++
 src/qemu/qemu_block.h |  3 +++
 2 files changed, 18 insertions(+)

diff --git a/src/qemu/qemu_block.c b/src/qemu/qemu_block.c
index 7fb12ea5a..4c0a5eb78 100644
--- a/src/qemu/qemu_block.c
+++ b/src/qemu/qemu_block.c
@@ -379,6 +379,21 @@ qemuBlockGetNodeData(virJSONValuePtr data)
 }
 
 
+/**
+ * qemuBlockStorageSourceSupportsConcurrentAccess:
+ * @src: disk storage source
+ *
+ * Returns true if the given storage format supports concurrent access from two
+ * separate processes.
+ */
+bool
+qemuBlockStorageSourceSupportsConcurrentAccess(virStorageSourcePtr src)
+{
+    /* no need to check in backing chain since only RAW storage supports this */
+    return src->format == VIR_STORAGE_FILE_RAW;
+}
+
+
 /**
  * qemuBlockStorageSourceBuildHostsJSONSocketAddress:
  * @src: disk storage source
diff --git a/src/qemu/qemu_block.h b/src/qemu/qemu_block.h
index f0a2c9aa7..ebf3149ce 100644
--- a/src/qemu/qemu_block.h
+++ b/src/qemu/qemu_block.h
@@ -53,6 +53,9 @@ qemuBlockNodeNamesDetect(virQEMUDriverPtr driver,
 virHashTablePtr
 qemuBlockGetNodeData(virJSONValuePtr data);
 
+bool
+qemuBlockStorageSourceSupportsConcurrentAccess(virStorageSourcePtr src);
+
 virJSONValuePtr
 qemuBlockStorageSourceGetBackendProps(virStorageSourcePtr src);