lvm: Add support for running vgcfgbackup/restore

Fixes: #565

Author: vojtechtrefny

docs/libblockdev-sections.txt

@@ -327,6 +327,8 @@ bd_lvm_vgextend
 bd_lvm_vgreduce
 bd_lvm_vglock_start
 bd_lvm_vglock_stop
+bd_lvm_vgcfgbackup
+bd_lvm_vgcfgrestore
 bd_lvm_add_vg_tags
 bd_lvm_delete_vg_tags
 bd_lvm_vginfo

src/lib/plugin_apis/lvm.api

@@ -738,6 +738,7 @@ typedef enum {
     BD_LVM_TECH_DEVICES,
     BD_LVM_TECH_SHARED,
     BD_LVM_TECH_CONFIG,
+    BD_LVM_TECH_VG_CFG_BACKUP_RESTORE,
 } BDLVMTech;
 
 typedef enum {
@@ -2044,4 +2045,40 @@ gboolean bd_lvm_devices_delete (const gchar *device, const gchar *devices_file,
  */
 gchar* bd_lvm_config_get (const gchar *section, const gchar *setting, const gchar *type, gboolean values_only, gboolean global_config, const BDExtraArg **extra, GError **error);
 
+/**
+ * bd_lvm_vgcfgbackup:
+ * @vg_name: name of the VG to backup configuration
+ * @backup_file: (nullable): file to save the backup to or %NULL for using the default backup file
+ *                           in /etc/lvm/backup
+ * @extra: (nullable) (array zero-terminated=1): extra options for the vgcfgbackup command
+ *                                               (just passed to LVM as is)
+ * @error: (out) (optional): place to store error (if any)
+ *
+ * Note: This function does not back up the data content of LVs. See `vgcfbackup(8)` man page
+ *       for more information.
+ *
+ * Returns: Whether the backup was successfully created or not.
+ *
+ * Tech category: %BD_LVM_TECH_VG_CFG_BACKUP_RESTORE no mode (it is ignored)
+ */
+gboolean bd_lvm_vgcfgbackup (const gchar *vg_name, const gchar *backup_file, const BDExtraArg **extra, GError **error);
+
+/**
+ * bd_lvm_vgcfgrestore:
+ * @vg_name: name of the VG to restore configuration
+ * @backup_file: (nullable): file to restore VG configuration from to or %NULL for using the
+ *                           latest backup in /etc/lvm/backup
+ * @extra: (nullable) (array zero-terminated=1): extra options for the vgcfgrestore command
+ *                                               (just passed to LVM as is)
+ * @error: (out) (optional): place to store error (if any)
+ *
+ * Note: This function restores VG configuration created by %bd_lvm_vgcfgbackup from given
+ *       @backup_file or from the latest backup in /etc/lvm/backup.
+ *
+ * Returns: Whether the configuration was successfully restored or not.
+ *
+ * Tech category: %BD_LVM_TECH_VG_CFG_BACKUP_RESTORE no mode (it is ignored)
+ */
+gboolean bd_lvm_vgcfgrestore (const gchar *vg_name, const gchar *backup_file, const BDExtraArg **extra, GError **error);
+
 #endif  /* BD_LVM_API */

src/plugins/lvm/lvm-common.c

@@ -787,3 +787,66 @@ gchar* bd_lvm_config_get (const gchar *section, const gchar *setting, const gcha
         return NULL;
     return g_strchomp (output);
 }
+
+gboolean _vgcfgbackup_restore (const gchar *command, const gchar *vg_name, const gchar *file, const BDExtraArg **extra, GError **error) {
+    const gchar *args[6] = {"lvm", NULL, NULL, NULL, NULL, NULL};
+    guint next_arg = 1;
+    gchar *output = NULL;
+    g_autofree gchar *config_arg = NULL;
+
+    args[next_arg++] = command;
+    if (file) {
+        args[next_arg++] = "-f";
+        args[next_arg++] = file;
+    }
+    args[next_arg++] = vg_name;
+
+    g_mutex_lock (&global_config_lock);
+    if (global_config_str) {
+        config_arg = g_strdup_printf ("--config=%s", global_config_str);
+        args[next_arg++] = config_arg;
+    }
+    g_mutex_unlock (&global_config_lock);
+
+    return bd_utils_exec_and_capture_output (args, extra, &output, error);
+}
+
+/**
+ * bd_lvm_vgcfgbackup:
+ * @vg_name: name of the VG to backup configuration
+ * @backup_file: (nullable): file to save the backup to or %NULL for using the default backup file
+ *                           in /etc/lvm/backup
+ * @extra: (nullable) (array zero-terminated=1): extra options for the vgcfgbackup command
+ *                                               (just passed to LVM as is)
+ * @error: (out) (optional): place to store error (if any)
+ *
+ * Note: This function does not back up the data content of LVs. See `vgcfbackup(8)` man page
+ *       for more information.
+ *
+ * Returns: Whether the backup was successfully created or not.
+ *
+ * Tech category: %BD_LVM_TECH_VG_CFG_BACKUP_RESTORE no mode (it is ignored)
+ */
+gboolean bd_lvm_vgcfgbackup (const gchar *vg_name, const gchar *backup_file, const BDExtraArg **extra, GError **error) {
+    return _vgcfgbackup_restore ("vgcfgbackup", vg_name, backup_file, extra, error);
+}
+
+/**
+ * bd_lvm_vgcfgrestore:
+ * @vg_name: name of the VG to restore configuration
+ * @backup_file: (nullable): file to restore VG configuration from to or %NULL for using the
+ *                           latest backup in /etc/lvm/backup
+ * @extra: (nullable) (array zero-terminated=1): extra options for the vgcfgrestore command
+ *                                               (just passed to LVM as is)
+ * @error: (out) (optional): place to store error (if any)
+ *
+ * Note: This function restores VG configuration created by %bd_lvm_vgcfgbackup from given
+ *       @backup_file or from the latest backup in /etc/lvm/backup.
+ *
+ * Returns: Whether the configuration was successfully restored or not.
+ *
+ * Tech category: %BD_LVM_TECH_VG_CFG_BACKUP_RESTORE no mode (it is ignored)
+ */
+gboolean bd_lvm_vgcfgrestore (const gchar *vg_name, const gchar *backup_file, const BDExtraArg **extra, GError **error) {
+    return _vgcfgbackup_restore ("vgcfgrestore", vg_name, backup_file, extra, error);
+}

src/plugins/lvm/lvm-dbus.c

@@ -382,6 +382,8 @@ gboolean bd_lvm_is_tech_avail (BDLVMTech tech, guint64 mode, GError **error) {
         return check_deps (&avail_deps, DEPS_LVMDEVICES_MASK, deps, DEPS_LAST, &deps_check_lock, error);
     case BD_LVM_TECH_CONFIG:
         return check_deps (&avail_deps, DEPS_LVMCONFIG_MASK, deps, DEPS_LAST, &deps_check_lock, error);
+    case BD_LVM_TECH_VG_CFG_BACKUP_RESTORE:
+        return check_deps (&avail_deps, DEPS_LVM_MASK, deps, DEPS_LAST, &deps_check_lock, error);
     default:
         /* everything is supported by this implementation of the plugin */
         return check_dbus_deps (&avail_dbus_deps, DBUS_DEPS_LVMDBUSD_MASK, dbus_deps, DBUS_DEPS_LAST, &deps_check_lock, error);

src/plugins/lvm/lvm.h

@@ -202,6 +202,7 @@ typedef enum {
     BD_LVM_TECH_DEVICES,
     BD_LVM_TECH_SHARED,
     BD_LVM_TECH_CONFIG,
+    BD_LVM_TECH_VG_CFG_BACKUP_RESTORE,
 } BDLVMTech;
 
 typedef enum {
@@ -256,6 +257,8 @@ gboolean bd_lvm_add_vg_tags (const gchar *vg_name, const gchar **tags, GError **
 gboolean bd_lvm_delete_vg_tags (const gchar *vg_name, const gchar **tags, GError **error);
 gboolean bd_lvm_vglock_start (const gchar *vg_name, const BDExtraArg **extra, GError **error);
 gboolean bd_lvm_vglock_stop (const gchar *vg_name, const BDExtraArg **extra, GError **error);
+gboolean bd_lvm_vgcfgbackup (const gchar *vg_name, const gchar *backup_file, const BDExtraArg **extra, GError **error);
+gboolean bd_lvm_vgcfgrestore (const gchar *vg_name, const gchar *backup_file, const BDExtraArg **extra, GError **error);
 BDLVMVGdata* bd_lvm_vginfo (const gchar *vg_name, GError **error);
 BDLVMVGdata** bd_lvm_vgs (GError **error);
 

tests/lvm_dbus_tests.py

@@ -6,6 +6,7 @@
 import re
 import shutil
 import time
+import tempfile
 from contextlib import contextmanager
 from packaging.version import Version
 from itertools import chain
@@ -2404,3 +2405,33 @@ def test_set_empty_config(self):
         BlockDev.lvm_set_global_config("")
         succ = BlockDev.lvm_pvremove(self.loop_dev)
         self.assertTrue(succ)
+
+
+class LvmTestBackupRestore(LvmPVVGTestCase):
+    def test_vgcfgbackup_restore(self):
+        """Verify that it is possible to backup and restore VG configuration"""
+
+        succ = BlockDev.lvm_pvcreate(self.loop_dev, 0, 0, None)
+        self.assertTrue(succ)
+
+        succ = BlockDev.lvm_vgcreate("testVG", [self.loop_dev], 0, None)
+        self.assertTrue(succ)
+
+        with tempfile.TemporaryDirectory() as d:
+            succ = BlockDev.lvm_vgcfgbackup("testVG", os.path.join(d, "testVGbackup"))
+            self.assertTrue(succ)
+            self.assertTrue(os.path.isfile(os.path.join(d, "testVGbackup")))
+
+            succ = BlockDev.lvm_vgcfgrestore("testVG", os.path.join(d, "testVGbackup"))
+            self.assertTrue(succ)
+
+        succ = BlockDev.lvm_vgcfgbackup("testVG", None)
+        self.assertTrue(succ)
+
+        # default location is /etc/lvm/backup/<vgname>
+        self.assertTrue(os.path.isfile("/etc/lvm/backup/testVG"))
+
+        succ = BlockDev.lvm_vgcfgrestore("testVG", None)
+        self.assertTrue(succ)
+
+        os.unlink("/etc/lvm/backup/testVG")

tests/lvm_test.py

@@ -5,6 +5,7 @@
 import overrides_hack
 import re
 import shutil
+import tempfile
 import time
 from contextlib import contextmanager
 from packaging.version import Version
@@ -2291,3 +2292,33 @@ def test_set_empty_config(self):
         BlockDev.lvm_set_global_config("")
         succ = BlockDev.lvm_pvremove(self.loop_dev)
         self.assertTrue(succ)
+
+
+class LvmTestBackupRestore(LvmPVVGTestCase):
+    def test_vgcfgbackup_restore(self):
+        """Verify that it is possible to backup and restore VG configuration"""
+
+        succ = BlockDev.lvm_pvcreate(self.loop_dev, 0, 0, None)
+        self.assertTrue(succ)
+
+        succ = BlockDev.lvm_vgcreate("testVG", [self.loop_dev], 0, None)
+        self.assertTrue(succ)
+
+        with tempfile.TemporaryDirectory() as d:
+            succ = BlockDev.lvm_vgcfgbackup("testVG", os.path.join(d, "testVGbackup"))
+            self.assertTrue(succ)
+            self.assertTrue(os.path.isfile(os.path.join(d, "testVGbackup")))
+
+            succ = BlockDev.lvm_vgcfgrestore("testVG", os.path.join(d, "testVGbackup"))
+            self.assertTrue(succ)
+
+        succ = BlockDev.lvm_vgcfgbackup("testVG", None)
+        self.assertTrue(succ)
+
+        # default location is /etc/lvm/backup/<vgname>
+        self.assertTrue(os.path.isfile("/etc/lvm/backup/testVG"))
+
+        succ = BlockDev.lvm_vgcfgrestore("testVG", None)
+        self.assertTrue(succ)
+
+        os.unlink("/etc/lvm/backup/testVG")