[PATCH 1/2] qemu: introduce locking option for disk source of qemu

[Masayoshi Mizuma <msys.mizuma@xxxxxxxxx>]

From: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx>

Introduce locking option for disk source of qemu.
It may be useful to avoid file lock issues.
locking option supports three switches; 'auto', 'on' and 'off'.
The default behaivor will work if locking option isn't set.

Example of the usage:

  <disk type='file' device='disk'>
    <driver name='qemu' type='qcow2' cache='none'/>
    <source file='/tmp/QEMUGuest1.img' locking='off'/>
    <target dev='hda' bus='ide'/>
    <address type='drive' controller='0' bus='0' target='0' unit='0'/>
  </disk>

Signed-off-by: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx>
---
 docs/schemas/domaincommon.rng  |  9 +++++++++
 src/conf/domain_conf.c         |  8 ++++++++
 src/conf/storage_source_conf.c |  9 +++++++++
 src/conf/storage_source_conf.h | 14 ++++++++++++++
 src/libvirt_private.syms       |  1 +
 src/qemu/qemu_block.c          |  5 +++++
 6 files changed, 46 insertions(+)

diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index a4bddcf132..d33d853f31 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -1676,6 +1676,15 @@
             <ref name="devSeclabel"/>
           </zeroOrMore>
         </interleave>
+        <optional>
+          <attribute name="locking">
+            <choice>
+              <value>auto</value>
+              <value>on</value>
+              <value>off</value>
+            </choice>
+          </attribute>
+        </optional>
       </element>
     </optional>
   </define>
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index dab4f10326..067ffa877b 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -8540,6 +8540,7 @@ virDomainStorageSourceParse(xmlNodePtr node,
 {
     VIR_XPATH_NODE_AUTORESTORE(ctxt)
     xmlNodePtr tmp;
+    char *locking;
 
     ctxt->node = node;
 
@@ -8606,6 +8607,9 @@ virDomainStorageSourceParse(xmlNodePtr node,
             return -1;
     }
 
+    if ((locking = virXMLPropString(node, "locking")))
+        src->locking = virStorageFileLockingTypeFromString(locking);
+
     return 0;
 }
 
@@ -24102,6 +24106,10 @@ virDomainDiskSourceFormat(virBufferPtr buf,
         return -1;
     }
 
+    if (src->locking != VIR_STORAGE_FILE_LOCKING_DEFAULT)
+        virBufferEscapeString(&attrBuf, " locking='%s'",
+                              virStorageFileLockingTypeToString(src->locking));
+
     virDomainDiskSourceFormatSlices(&childBuf, src);
 
     if (src->type != VIR_STORAGE_TYPE_NETWORK)
diff --git a/src/conf/storage_source_conf.c b/src/conf/storage_source_conf.c
index dab5e855f5..3ac0c7f75b 100644
--- a/src/conf/storage_source_conf.c
+++ b/src/conf/storage_source_conf.c
@@ -49,6 +49,15 @@ VIR_ENUM_IMPL(virStorage,
 );
 
 
+VIR_ENUM_IMPL(virStorageFileLocking,
+              VIR_STORAGE_FILE_LOCKING_LAST,
+              "default",
+              "auto",
+              "on",
+              "off",
+);
+
+
 VIR_ENUM_IMPL(virStorageFileFormat,
               VIR_STORAGE_FILE_LAST,
               "none",
diff --git a/src/conf/storage_source_conf.h b/src/conf/storage_source_conf.h
index e66ccdedef..6f5b165504 100644
--- a/src/conf/storage_source_conf.h
+++ b/src/conf/storage_source_conf.h
@@ -82,6 +82,18 @@ typedef enum {
 VIR_ENUM_DECL(virStorageFileFormat);
 
 
+typedef enum {
+    VIR_STORAGE_FILE_LOCKING_DEFAULT = 0,
+    VIR_STORAGE_FILE_LOCKING_AUTO,
+    VIR_STORAGE_FILE_LOCKING_ON,
+    VIR_STORAGE_FILE_LOCKING_OFF,
+
+    VIR_STORAGE_FILE_LOCKING_LAST,
+} virStorageFileLocking;
+
+VIR_ENUM_DECL(virStorageFileLocking);
+
+
 typedef enum {
     VIR_STORAGE_FILE_FEATURE_LAZY_REFCOUNTS = 0,
 
@@ -394,6 +406,8 @@ struct _virStorageSource {
     char *nfs_group;
     uid_t nfs_uid;
     gid_t nfs_gid;
+
+    int locking; /* enum virStorageFileLocking */
 };
 
 G_DEFINE_AUTOPTR_CLEANUP_FUNC(virStorageSource, virObjectUnref);
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index fbaf16704b..c72d2161b2 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1068,6 +1068,7 @@ virStorageFileFeatureTypeFromString;
 virStorageFileFeatureTypeToString;
 virStorageFileFormatTypeFromString;
 virStorageFileFormatTypeToString;
+virStorageFileLockingTypeToString;
 virStorageNetHostDefClear;
 virStorageNetHostDefCopy;
 virStorageNetHostDefFree;
diff --git a/src/qemu/qemu_block.c b/src/qemu/qemu_block.c
index d845a3312d..d7eec16ab6 100644
--- a/src/qemu/qemu_block.c
+++ b/src/qemu/qemu_block.c
@@ -1015,6 +1015,7 @@ qemuBlockStorageSourceGetFileProps(virStorageSourcePtr src,
 {
     const char *iomode = NULL;
     const char *prManagerAlias = NULL;
+    const char *locking = NULL;
     virJSONValuePtr ret = NULL;
 
     if (!onlytarget) {
@@ -1023,12 +1024,16 @@ qemuBlockStorageSourceGetFileProps(virStorageSourcePtr src,
 
         if (src->iomode != VIR_DOMAIN_DISK_IO_DEFAULT)
             iomode = virDomainDiskIoTypeToString(src->iomode);
+
+        if (src->locking != VIR_STORAGE_FILE_LOCKING_DEFAULT)
+            locking = virStorageFileLockingTypeToString(src->locking);
     }
 
     ignore_value(virJSONValueObjectCreate(&ret,
                                           "s:filename", src->path,
                                           "S:aio", iomode,
                                           "S:pr-manager", prManagerAlias,
+                                          "S:locking", locking,
                                           NULL) < 0);
     return ret;
 }
-- 
2.27.0