thin: allow restore with --force

Allow restoring metadata with thin pool volumes.
No validation is done for this case within vgcfgrestore tool -
thus incorrect metadata may lead to destruction of pool content.

WHATS_NEW

@@ -1,5 +1,6 @@
 Version 2.02.99 - 
 ===================================
+  Allow forced vgcfgrestore of lvm2 metadata with thin volumes.
   Recognise STEC skd devices in filter.
   Recognise Violin Memory vtms devices in filter.
   Add lvm.conf thin pool defs thin_pool_{chunk_size|discards|zero}.

lib/format_text/archiver.c

@@ -347,7 +347,7 @@ int backup_restore_vg(struct cmd_context *cmd, struct volume_group *vg)
 
 /* ORPHAN and VG locks held before calling this */
 int backup_restore_from_file(struct cmd_context *cmd, const char *vg_name,
-			     const char *file)
+			     const char *file, int force)
 {
 	struct volume_group *vg;
 	int missing_pvs, r = 0;
@@ -360,14 +360,20 @@ int backup_restore_from_file(struct cmd_context *cmd, const char *vg_name,
 		return_0;
 
 	/* FIXME: Restore support is missing for now */
-	dm_list_iterate_items(lvl, &vg->lvs)
+	dm_list_iterate_items(lvl, &vg->lvs) {
 		if (lv_is_thin_type(lvl->lv)) {
-			log_error("Cannot restore Volume Group %s with "
-				  "thin logical volumes. "
-				  "(not yet supported).", vg->name);
-			r = 0;
-			goto out;
+			if (!force) {
+				log_error("Consider using option --force to restore "
+					  "Volume Group %s with thin volumes.",
+					  vg->name);
+				goto out;
+			} else {
+				log_warn("WARNING: Forced restore of Volume Group "
+					 "%s with thin volumes.", vg->name);
+				break;
+			}
 		}
+	}
 
 	missing_pvs = vg_missing_pv_count(vg);
 	if (missing_pvs == 0)
@@ -381,7 +387,7 @@ out:
 	return r;
 }
 
-int backup_restore(struct cmd_context *cmd, const char *vg_name)
+int backup_restore(struct cmd_context *cmd, const char *vg_name, int force)
 {
 	char path[PATH_MAX];
 
@@ -391,7 +397,7 @@ int backup_restore(struct cmd_context *cmd, const char *vg_name)
 		return 0;
 	}
 
-	return backup_restore_from_file(cmd, vg_name, path);
+	return backup_restore_from_file(cmd, vg_name, path, force);
 }
 
 int backup_to_file(const char *file, const char *desc, struct volume_group *vg)

lib/format_text/archiver.h

@@ -53,8 +53,8 @@ struct volume_group *backup_read_vg(struct cmd_context *cmd,
 				    const char *vg_name, const char *file);
 int backup_restore_vg(struct cmd_context *cmd, struct volume_group *vg);
 int backup_restore_from_file(struct cmd_context *cmd, const char *vg_name,
-			     const char *file);
-int backup_restore(struct cmd_context *cmd, const char *vg_name);
+			     const char *file, int force);
+int backup_restore(struct cmd_context *cmd, const char *vg_name, int force);
 
 int backup_to_file(const char *file, const char *desc, struct volume_group *vg);
 

man/vgcfgrestore.8.in

@@ -6,6 +6,7 @@ vgcfgrestore \- restore volume group descriptor area
 .RB [ \-d | \-\-debug ]
 .RB [ \-f | \-\-file
 .RI < filename >]
+.RB [ \-\-force ]
 .RB [ \-l [ l ]| \-\-list ]
 .RB [ \-h | \-\-help ]
 .RB [ \-M | \-\-metadatatype
@@ -32,6 +33,14 @@ May be used with the \fB\-f\fP option.  Does not restore \fIVolumeGroupName\fP.
 Name of LVM metadata backup file
 Specifies a metadata backup or archive file to be used for restoring 
 VolumeGroupName.  Often this file has been created with \fBvgcfgbackup\fP.
+.TP
+.B \-\-force
+To restore metadata with thin pool volumes, user currently
+needs to use this flag. The tool DOES NOT make any validation.
+.br
+WARNING: Restoring lvm2 metadata that are not matching thin pool
+kernel metadata may lead to the destruction of the pool content.
+Use with extreme caution.
 .SH REPLACING PHYSICAL VOLUMES
 \fBvgdisplay \-\-partial \-\-verbose\fP will show you the UUIDs and sizes of
 any PVs that are no longer present.

tools/args.h

@@ -73,6 +73,7 @@ arg(poll_ARG, '\0', "poll", yes_no_arg, 0)
 arg(poolmetadata_ARG, '\0', "poolmetadata", string_arg, 0)
 arg(poolmetadatasize_ARG, '\0', "poolmetadatasize", size_mb_arg, 0)
 arg(discards_ARG, '\0', "discards", discards_arg, 0)
+arg(force_long_ARG, '\0', "force", NULL, ARG_COUNTABLE)
 arg(stripes_long_ARG, '\0', "stripes", int_arg, 0)
 arg(sysinit_ARG, '\0', "sysinit", NULL, 0)
 arg(thinpool_ARG, '\0', "thinpool", string_arg, 0)

tools/commands.h

@@ -725,6 +725,7 @@ xx(vgcfgrestore,
    "vgcfgrestore " "\n"
    "\t[-d|--debug] " "\n"
    "\t[-f|--file filename] " "\n"
+   "\t[--force]\n"
    "\t[-l[l]|--list [--list]]" "\n"
    "\t[-M|--metadatatype 1|2]" "\n"
    "\t[-h|--help]" "\n"
@@ -733,7 +734,7 @@ xx(vgcfgrestore,
    "\t[--version] " "\n"
    "\tVolumeGroupName",
 
-   file_ARG, list_ARG, metadatatype_ARG, test_ARG)
+   file_ARG, force_long_ARG, list_ARG, metadatatype_ARG, test_ARG)
 
 xx(vgchange,
    "Change volume group attributes",

tools/vgcfgrestore.c

@@ -62,8 +62,9 @@ int vgcfgrestore(struct cmd_context *cmd, int argc, char **argv)
 
 	if (!(arg_count(cmd, file_ARG) ?
 	      backup_restore_from_file(cmd, vg_name,
-				       arg_str_value(cmd, file_ARG, "")) :
-	      backup_restore(cmd, vg_name))) {
+				       arg_str_value(cmd, file_ARG, ""),
+				       arg_count(cmd, force_long_ARG)) :
+	      backup_restore(cmd, vg_name, arg_count(cmd, force_long_ARG)))) {
 		unlock_vg(cmd, VG_ORPHANS);
 		unlock_vg(cmd, vg_name);
 		log_error("Restore failed.");