[libvirt] [PATCH v2 2/5] storage: Turn storage backends into dynamic modules

Peter Krempa pkrempa at redhat.com
Tue Feb 21 11:55:08 UTC 2017


If driver modules are enabled turn storage driver backends into
dynamically loadable objects. This will allow greater modularity for
binary distributions, where heavyweight dependencies as rbd and gluster
can be avoided by selecting only a subset of drivers if the rest is not
necessary.

The storage modules are installed into 'LIBDIR/libvirt/storage-backend/'
and users can't override the location by using
'LIBVIRT_STORAGE_BACKEND_DIR' environment variable.

rpm based distros will at this point install all the backends when
libvirt-daemon-driver-storage package is installed.
---
 libvirt.spec.in               | 17 +++++++++
 src/Makefile.am               | 85 ++++++++++++++++++++++++++++++++++++++++++-
 src/storage/storage_backend.c | 60 +++++++++++++++++++++++-------
 tests/Makefile.am             |  4 +-
 4 files changed, 151 insertions(+), 15 deletions(-)

diff --git a/libvirt.spec.in b/libvirt.spec.in
index f4ea89d77..a9af97f10 100644
--- a/libvirt.spec.in
+++ b/libvirt.spec.in
@@ -1239,6 +1239,8 @@ rm -f $RPM_BUILD_ROOT%{_libdir}/libvirt/lock-driver/*.la
 rm -f $RPM_BUILD_ROOT%{_libdir}/libvirt/lock-driver/*.a
 rm -f $RPM_BUILD_ROOT%{_libdir}/libvirt/connection-driver/*.la
 rm -f $RPM_BUILD_ROOT%{_libdir}/libvirt/connection-driver/*.a
+rm -f $RPM_BUILD_ROOT%{_libdir}/libvirt/storage-backend/*.la
+rm -f $RPM_BUILD_ROOT%{_libdir}/libvirt/storage-backend/*.a
 %if %{with_wireshark}
     %if 0%{fedora} >= 24
 rm -f $RPM_BUILD_ROOT%{_libdir}/wireshark/plugins/libvirt.la
@@ -1694,6 +1696,21 @@ exit 0
 %files daemon-driver-storage
 %attr(0755, root, root) %{_libexecdir}/libvirt_parthelper
 %{_libdir}/%{name}/connection-driver/libvirt_driver_storage.so
+%{_libdir}/%{name}/storage-backend/libvirt_storage_backend_fs.so
+%{_libdir}/%{name}/storage-backend/libvirt_storage_backend_disk.so
+%{_libdir}/%{name}/storage-backend/libvirt_storage_backend_logical.so
+%{_libdir}/%{name}/storage-backend/libvirt_storage_backend_scsi.so
+%{_libdir}/%{name}/storage-backend/libvirt_storage_backend_iscsi.so
+%{_libdir}/%{name}/storage-backend/libvirt_storage_backend_mpath.so
+%if %{with_storage_gluster}
+%{_libdir}/%{name}/storage-backend/libvirt_storage_backend_gluster.so
+%endif
+%if %{with_storage_rbd}
+%{_libdir}/%{name}/storage-backend/libvirt_storage_backend_rbd.so
+%endif
+%if %{with_storage_sheepdog}
+%{_libdir}/%{name}/storage-backend/libvirt_storage_backend_sheepdog.so
+%endif

 %if %{with_qemu}
 %files daemon-driver-qemu
diff --git a/src/Makefile.am b/src/Makefile.am
index 7099f1b88..a85cd0df8 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -972,9 +972,12 @@ SECRET_DRIVER_SOURCES =						\
 		secret/secret_driver.h secret/secret_driver.c

 # Storage backend specific impls
+STORAGE_DRIVER_BACKEND_SOURCES = \
+		storage/storage_backend.h storage/storage_backend.c
+
 STORAGE_DRIVER_SOURCES =						\
 		storage/storage_driver.h storage/storage_driver.c	\
-		storage/storage_backend.h storage/storage_backend.c \
+		$(STORAGE_DRIVER_BACKEND_SOURCES) \
 		storage/storage_util.h storage/storage_util.c

 STORAGE_DRIVER_FS_SOURCES =					\
@@ -1661,6 +1664,12 @@ if WITH_BLKID
 libvirt_driver_storage_impl_la_CFLAGS += $(BLKID_CFLAGS)
 libvirt_driver_storage_impl_la_LIBADD += $(BLKID_LIBS)
 endif WITH_BLKID
+
+if WITH_DRIVER_MODULES
+storagebackenddir = $(libdir)/libvirt/storage-backend
+storagebackend_LTLIBRARIES =
+endif WITH_DRIVER_MODULES
+
 if WITH_STORAGE
 noinst_LTLIBRARIES += libvirt_driver_storage_impl.la
 libvirt_driver_storage_la_SOURCES =
@@ -1682,8 +1691,14 @@ libvirt_storage_backend_fs_la_CFLAGS =	\
 	-I$(srcdir)/conf \
 	$(AM_CFLAGS)

+if WITH_DRIVER_MODULES
+storagebackend_LTLIBRARIES += libvirt_storage_backend_fs.la
+libvirt_storage_backend_fs_la_LDFLAGS = \
+	-module -avoid-version $(AM_LDFLAGS)
+else ! WITH_DRIVER_MODULES
 noinst_LTLIBRARIES += libvirt_storage_backend_fs.la
 libvirt_driver_storage_impl_la_LIBADD += libvirt_storage_backend_fs.la
+endif ! WITH_DRIVER_MODULES
 endif WITH_STORAGE

 if WITH_STORAGE_LVM
@@ -1693,9 +1708,15 @@ libvirt_storage_backend_logical_la_CFLAGS = \
 	-I$(srcdir)/conf \
 	$(AM_CFLAGS)

+if WITH_DRIVER_MODULES
+storagebackend_LTLIBRARIES += libvirt_storage_backend_logical.la
+libvirt_storage_backend_logical_la_LDFLAGS = \
+	-module -avoid-version $(AM_LDFLAGS)
+else ! WITH_DRIVER_MODULES
 noinst_LTLIBRARIES += libvirt_storage_backend_logical.la
 libvirt_driver_storage_impl_la_LIBADD += \
 	libvirt_storage_backend_logical.la
+endif ! WITH_DRIVER_MODULES
 endif WITH_STORAGE_LVM

 if WITH_STORAGE_ISCSI
@@ -1706,9 +1727,15 @@ libvirt_storage_backend_iscsi_la_CFLAGS = \
 	-I$(srcdir)/secret \
 	$(AM_CFLAGS)

+if WITH_DRIVER_MODULES
+storagebackend_LTLIBRARIES += libvirt_storage_backend_iscsi.la
+libvirt_storage_backend_iscsi_la_LDFLAGS = \
+	-module -avoid-version $(AM_LDFLAGS)
+else ! WITH_DRIVER_MODULES
 noinst_LTLIBRARIES += libvirt_storage_backend_iscsi.la
 libvirt_driver_storage_impl_la_LIBADD += \
 	libvirt_storage_backend_iscsi.la
+endif ! WITH_DRIVER_MODULES
 endif WITH_STORAGE_ISCSI

 if WITH_STORAGE_SCSI
@@ -1717,8 +1744,14 @@ libvirt_storage_backend_scsi_la_CFLAGS = \
 	-I$(srcdir)/conf \
 	$(AM_CFLAGS)

+if WITH_DRIVER_MODULES
+storagebackend_LTLIBRARIES += libvirt_storage_backend_scsi.la
+libvirt_storage_backend_scsi_la_LDFLAGS = \
+	-module -avoid-version $(AM_LDFLAGS)
+else ! WITH_DRIVER_MODULES
 noinst_LTLIBRARIES += libvirt_storage_backend_scsi.la
 libvirt_driver_storage_impl_la_LIBADD += libvirt_storage_backend_scsi.la
+endif ! WITH_DRIVER_MODULES
 endif WITH_STORAGE_SCSI

 if WITH_STORAGE_MPATH
@@ -1730,9 +1763,15 @@ libvirt_storage_backend_mpath_la_CFLAGS =	\
 	$(DEVMAPPER_CFLAGS) \
 	$(AM_CFLAGS)

+if WITH_DRIVER_MODULES
+storagebackend_LTLIBRARIES += libvirt_storage_backend_mpath.la
+libvirt_storage_backend_mpath_la_LDFLAGS = \
+	-module -avoid-version $(AM_LDFLAGS)
+else ! WITH_DRIVER_MODULES
 noinst_LTLIBRARIES += libvirt_storage_backend_mpath.la
 libvirt_driver_storage_impl_la_LIBADD += \
 	libvirt_storage_backend_mpath.la
+endif ! WITH_DRIVER_MODULES
 endif WITH_STORAGE_MPATH

 if WITH_STORAGE_DISK
@@ -1741,8 +1780,14 @@ libvirt_storage_backend_disk_la_CFLAGS =	\
 	-I$(srcdir)/conf \
 	$(AM_CFLAGS)

+if WITH_DRIVER_MODULES
+storagebackend_LTLIBRARIES += libvirt_storage_backend_disk.la
+libvirt_storage_backend_disk_la_LDFLAGS = \
+	-module -avoid-version $(AM_LDFLAGS)
+else ! WITH_DRIVER_MODULES
 noinst_LTLIBRARIES += libvirt_storage_backend_disk.la
 libvirt_driver_storage_impl_la_LIBADD += libvirt_storage_backend_disk.la
+endif ! WITH_DRIVER_MODULES
 endif WITH_STORAGE_DISK

 if WITH_STORAGE_RBD
@@ -1753,8 +1798,14 @@ libvirt_storage_backend_rbd_la_CFLAGS = \
 	-I$(srcdir)/secret \
 	$(AM_CFLAGS)

+if WITH_DRIVER_MODULES
+storagebackend_LTLIBRARIES += libvirt_storage_backend_rbd.la
+libvirt_storage_backend_rbd_la_LDFLAGS = \
+	-module -avoid-version $(AM_LDFLAGS)
+else ! WITH_DRIVER_MODULES
 noinst_LTLIBRARIES += libvirt_storage_backend_rbd.la
 libvirt_driver_storage_impl_la_LIBADD += libvirt_storage_backend_rbd.la
+endif ! WITH_DRIVER_MODULES
 endif WITH_STORAGE_RBD

 if WITH_STORAGE_SHEEPDOG
@@ -1764,9 +1815,23 @@ libvirt_storage_backend_sheepdog_la_CFLAGS = \
 	-I$(srcdir)/conf \
 	$(AM_CFLAGS)

+libvirt_storage_backend_sheepdog_priv_la_SOURCES = \
+	$(STORAGE_DRIVER_SHEEPDOG_SOURCES) \
+	$(STORAGE_DRIVER_BACKEND_SOURCES)
+libvirt_storage_backend_sheepdog_priv_la_CFLAGS = \
+	-I$(srcdir)/conf \
+	$(AM_CFLAGS)
+noinst_LTLIBRARIES += libvirt_storage_backend_sheepdog_priv.la
+
+if WITH_DRIVER_MODULES
+storagebackend_LTLIBRARIES += libvirt_storage_backend_sheepdog.la
+libvirt_storage_backend_sheepdog_la_LDFLAGS = \
+	-module -avoid-version $(AM_LDFLAGS)
+else ! WITH_DRIVER_MODULES
 noinst_LTLIBRARIES += libvirt_storage_backend_sheepdog.la
 libvirt_driver_storage_impl_la_LIBADD += \
 	libvirt_storage_backend_sheepdog.la
+endif ! WITH_DRIVER_MODULES
 endif WITH_STORAGE_SHEEPDOG

 if WITH_STORAGE_GLUSTER
@@ -1778,9 +1843,15 @@ libvirt_storage_backend_gluster_la_CFLAGS = \
 	$(GLUSTERFS_CFLAGS) \
 	$(AM_CFLAGS)

+if WITH_DRIVER_MODULES
+storagebackend_LTLIBRARIES += libvirt_storage_backend_gluster.la
+libvirt_storage_backend_gluster_la_LDFLAGS = \
+	-module -avoid-version $(AM_LDFLAGS)
+else ! WITH_DRIVER_MODULES
 noinst_LTLIBRARIES += libvirt_storage_backend_gluster.la
 libvirt_driver_storage_impl_la_LIBADD += \
 	libvirt_storage_backend_gluster.la
+endif ! WITH_DRIVER_MODULES
 endif WITH_STORAGE_GLUSTER

 if WITH_STORAGE_ZFS
@@ -1789,8 +1860,14 @@ libvirt_storage_backend_zfs_la_CFLAGS =	\
 	-I$(srcdir)/conf \
 	$(AM_CFLAGS)

+if WITH_DRIVER_MODULES
+storagebackend_LTLIBRARIES += libvirt_storage_backend_zfs.la
+libvirt_storage_backend_zfs_la_LDFLAGS = \
+	-module -avoid-version $(AM_LDFLAGS)
+else ! WITH_DRIVER_MODULES
 noinst_LTLIBRARIES += libvirt_storage_backend_zfs.la
 libvirt_driver_storage_impl_la_LIBADD += libvirt_storage_backend_zfs.la
+endif ! WITH_DRIVER_MODULES
 endif WITH_STORAGE_ZFS

 if WITH_STORAGE_VSTORAGE
@@ -1800,9 +1877,15 @@ libvirt_storage_backend_vstorage_la_CFLAGS =	\
 	-I$(srcdir)/conf \
 	$(AM_CFLAGS)

+if WITH_DRIVER_MODULES
+storagebackend_LTLIBRARIES += libvirt_storage_backend_vstorage.la
+libvirt_storage_backend_vstorage_la_LDFLAGS = \
+	-module -avoid-version $(AM_LDFLAGS)
+else ! WITH_DRIVER_MODULES
 noinst_LTLIBRARIES += libvirt_storage_backend_vstorage.la
 libvirt_driver_storage_impl_la_LIBADD += \
 	libvirt_storage_backend_vstorage.la
+endif ! WITH_DRIVER_MODULES
 endif WITH_STORAGE_VSTORAGE

 if WITH_NODE_DEVICES
diff --git a/src/storage/storage_backend.c b/src/storage/storage_backend.c
index d8099be36..32f45e841 100644
--- a/src/storage/storage_backend.c
+++ b/src/storage/storage_backend.c
@@ -33,6 +33,8 @@
 #include "virstoragefile.h"
 #include "storage_backend.h"
 #include "virlog.h"
+#include "virfile.h"
+#include "configmake.h"

 #if WITH_STORAGE_LVM
 # include "storage_backend_logical.h"
@@ -79,45 +81,77 @@ static size_t virStorageBackendsCount;
 static virStorageFileBackendPtr virStorageFileBackends[VIR_STORAGE_BACKENDS_MAX];
 static size_t virStorageFileBackendsCount;

-#define VIR_STORAGE_BACKEND_REGISTER(name)                                     \
-    if (name() < 0)                                                            \
+#if WITH_DRIVER_MODULES
+
+# define STORAGE_BACKEND_MODULE_DIR LIBDIR "/libvirt/storage-backend"
+
+static int
+virStorageDriverLoadBackendModule(const char *name,
+                                  const char *regfunc)
+{
+    char *modfile = NULL;
+    int ret;
+
+    if (!(modfile = virFileFindResourceFull(name,
+                                            "libvirt_storage_backend_",
+                                            ".so",
+                                            abs_topbuilddir "/src/.libs",
+                                            STORAGE_BACKEND_MODULE_DIR,
+                                            "LIBVIRT_STORAGE_BACKEND_DIR")))
+        return 1;
+
+    ret = virDriverLoadModuleFull(modfile, regfunc, NULL);
+
+    VIR_FREE(modfile);
+
+    return ret;
+}
+
+
+# define VIR_STORAGE_BACKEND_REGISTER(func, module)                            \
+    if (virStorageDriverLoadBackendModule(module, #func) < 0)                  \
+        return -1
+#else
+# define VIR_STORAGE_BACKEND_REGISTER(func, module)                            \
+    if (func() < 0)                                                            \
         return -1
+#endif

 int
 virStorageBackendDriversRegister(void)
 {
 #if WITH_STORAGE_DIR || WITH_STORAGE_FS
-    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendFsRegister);
+    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendFsRegister, "fs");
 #endif
 #if WITH_STORAGE_LVM
-    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendLogicalRegister);
+    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendLogicalRegister, "logical");
 #endif
 #if WITH_STORAGE_ISCSI
-    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendISCSIRegister);
+    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendISCSIRegister, "iscsi");
 #endif
 #if WITH_STORAGE_SCSI
-    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendSCSIRegister);
+    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendSCSIRegister, "scsi");
 #endif
 #if WITH_STORAGE_MPATH
-    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendMpathRegister);
+    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendMpathRegister, "mpath");
 #endif
 #if WITH_STORAGE_DISK
-    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendDiskRegister);
+    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendDiskRegister, "disk");
 #endif
 #if WITH_STORAGE_RBD
-    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendRBDRegister);
+    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendRBDRegister, "rbd");
 #endif
 #if WITH_STORAGE_SHEEPDOG
-    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendSheepdogRegister);
+    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendSheepdogRegister, "sheepdog");
 #endif
 #if WITH_STORAGE_GLUSTER
-    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendGlusterRegister);
+    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendGlusterRegister, "gluster");
 #endif
 #if WITH_STORAGE_ZFS
-    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendZFSRegister);
+    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendZFSRegister, "zfs");
 #endif
 #if WITH_STORAGE_VSTORAGE
-    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendVstorageRegister);
+    VIR_STORAGE_BACKEND_REGISTER(virStorageBackendVstorageRegister, "vstorage");
 #endif

     return 0;
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 32a7282d4..35e82abf5 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -805,7 +805,9 @@ storagebackendsheepdogtest_SOURCES = \
 	storagebackendsheepdogtest.c \
 	testutils.c testutils.h
 storagebackendsheepdogtest_LDADD = \
-	../src/libvirt_driver_storage_impl.la $(LDADDS)
+	../src/libvirt_driver_storage_impl.la \
+	../src/libvirt_storage_backend_sheepdog_priv.la \
+	$(LDADDS)
 else ! WITH_STORAGE_SHEEPDOG
 EXTRA_DIST += storagebackendsheepdogtest.c
 endif ! WITH_STORAGE_SHEEPDOG
-- 
2.11.1




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