nilfs2: Using nobarrier option instead of barrier=off

Since most of fs using nofoobar style option,
modified barrier=off option as nobarrier.
Signed-off-by: Jiro SEKIBA <jir@unicus.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

Documentation/filesystems/nilfs2.txt

@@ -49,8 +49,7 @@ Mount options
 NILFS2 supports the following mount options:
 (*) == default
 
-barrier=on(*)		This enables/disables barriers. barrier=off disables
-			it, barrier=on enables it.
+nobarrier		Disables barriers.
 errors=continue(*)	Keep going on a filesystem error.
 errors=remount-ro	Remount the filesystem read-only on an error.
 errors=panic		Panic and halt the machine if an error occurs.

fs/nilfs2/super.c

@@ -490,7 +490,7 @@ static int nilfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
 	struct nilfs_sb_info *sbi = NILFS_SB(sb);
 
 	if (!nilfs_test_opt(sbi, BARRIER))
-		seq_printf(seq, ",barrier=off");
+		seq_printf(seq, ",nobarrier");
 	if (nilfs_test_opt(sbi, SNAPSHOT))
 		seq_printf(seq, ",cp=%llu",
 			   (unsigned long long int)sbi->s_snapshot_cno);
@@ -568,7 +568,7 @@ static const struct export_operations nilfs_export_ops = {
 
 enum {
 	Opt_err_cont, Opt_err_panic, Opt_err_ro,
-	Opt_barrier, Opt_snapshot, Opt_order,
+	Opt_nobarrier, Opt_snapshot, Opt_order,
 	Opt_err,
 };
 
@@ -576,7 +576,7 @@ static match_table_t tokens = {
 	{Opt_err_cont, "errors=continue"},
 	{Opt_err_panic, "errors=panic"},
 	{Opt_err_ro, "errors=remount-ro"},
-	{Opt_barrier, "barrier=%s"},
+	{Opt_nobarrier, "nobarrier"},
 	{Opt_snapshot, "cp=%u"},
 	{Opt_order, "order=%s"},
 	{Opt_err, NULL}
@@ -612,13 +612,8 @@ static int parse_options(char *options, struct super_block *sb)
 
 		token = match_token(p, tokens, args);
 		switch (token) {
-		case Opt_barrier:
-			if (match_bool(&args[0], &option))
-				return 0;
-			if (option)
-				nilfs_set_opt(sbi, BARRIER);
-			else
-				nilfs_clear_opt(sbi, BARRIER);
+		case Opt_nobarrier:
+			nilfs_clear_opt(sbi, BARRIER);
 			break;
 		case Opt_order:
 			if (strcmp(args[0].from, "relaxed") == 0)