scoutfs: add uniq_name mount option

Each mount is getting a specified unique name.  This can be used to
identify a reconnecting mount that indicates that an old instance of the
same unique name can no longer exist and doesn't need to be fenced.

Signed-off-by: Zach Brown <zab@versity.com>

kmod/src/format.h

@@ -349,6 +349,7 @@ struct scoutfs_betimespec {
 #define member_sizeof(TYPE, MEMBER) (sizeof(((TYPE *)0)->MEMBER))
 
 #define SCOUTFS_UUID_BYTES 16
+#define SCOUTFS_UNIQUE_NAME_MAX_BYTES	64 /* includes null */
 
 /* XXX ipv6 */
 struct scoutfs_inet_addr {

kmod/src/options.c

@@ -29,6 +29,7 @@
 static const match_table_t tokens = {
 	{Opt_listen, "listen=%s"},
 	{Opt_cluster, "cluster=%s"},
+	{Opt_uniq_name, "uniq_name=%s"},
 	{Opt_err, NULL}
 };
 
@@ -86,6 +87,12 @@ int scoutfs_parse_options(struct super_block *sb, char *options,
 			match_strlcpy(parsed->cluster_name, args,
 				      MAX_CLUSTER_NAME_LEN);
 			break;
+		case Opt_uniq_name:
+			len = match_strlcpy(parsed->uniq_name, args,
+					    SCOUTFS_UNIQUE_NAME_MAX_BYTES);
+			if (len == 0 || len > SCOUTFS_UNIQUE_NAME_MAX_BYTES)
+				return -EINVAL;
+			break;
 		default:
 			scoutfs_err(sb, "Unknown or malformed option, \"%s\"\n",
 				    p);
@@ -93,6 +100,11 @@ int scoutfs_parse_options(struct super_block *sb, char *options,
 		}
 	}
 
+	if (parsed->uniq_name[0] == '\0') {
+		scoutfs_err(sb, "must provide a uniq_name option");
+		return -EINVAL;
+	}
+
 	return 0;
 }
 

kmod/src/options.h

@@ -12,6 +12,7 @@ enum {
 	 * the number of items in each block as though the blocks were tiny.
 	 */
 	Opt_btree_force_tiny_blocks,
+	Opt_uniq_name,
 	Opt_err,
 };
 
@@ -20,6 +21,7 @@ struct mount_options
 {
 	struct scoutfs_inet_addr	listen_addr;
 	char				cluster_name[MAX_CLUSTER_NAME_LEN];
+	char uniq_name[SCOUTFS_UNIQUE_NAME_MAX_BYTES];
 };
 
 int scoutfs_parse_options(struct super_block *sb, char *options,