[PATCH v3] exfat: add the dummy mount options to be backward compatible with staging/exfat

[Namjae Jeon]

As Ubuntu and Fedora release new version used kernel version equal to or
higher than v5.4, They started to support kernel exfat filesystem.

Linus Torvalds reported mount error with new version of exfat on Fedora.

        exfat: Unknown parameter 'namecase'

This is because there is a difference in mount option between old
staging/exfat and new exfat.
And utf8, debug, and codepage options as well as namecase have been
removed from new exfat.

This patch add the dummy mount options as deprecated option to be backward
compatible with old one.

Reported-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
---
 v2:
  - fix checkpatch.pl warning(Missing Signed-off-by).
 v3:
  - use fs_param_deprecated instead of printing deprecated warning(Matthew Wilcox).

 fs/exfat/super.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/fs/exfat/super.c b/fs/exfat/super.c
index 0565d5539d57..a846ff555656 100644
--- a/fs/exfat/super.c
+++ b/fs/exfat/super.c
@@ -203,6 +203,12 @@ enum {
 	Opt_errors,
 	Opt_discard,
 	Opt_time_offset,
+
+	/* Deprecated options */
+	Opt_utf8,
+	Opt_debug,
+	Opt_namecase,
+	Opt_codepage,
 };
 
 static const struct constant_table exfat_param_enums[] = {
@@ -223,6 +229,14 @@ static const struct fs_parameter_spec exfat_parameters[] = {
 	fsparam_enum("errors",			Opt_errors, exfat_param_enums),
 	fsparam_flag("discard",			Opt_discard),
 	fsparam_s32("time_offset",		Opt_time_offset),
+	__fsparam(NULL, "utf8",			Opt_utf8, fs_param_deprecated,
+		  NULL),
+	__fsparam(NULL, "debug",		Opt_debug, fs_param_deprecated,
+		  NULL),
+	__fsparam(fs_param_is_u32, "namecase",	Opt_namecase,
+		  fs_param_deprecated, NULL),
+	__fsparam(fs_param_is_u32, "codepage",	Opt_codepage,
+		  fs_param_deprecated, NULL),
 	{}
 };
 
@@ -278,6 +292,11 @@ static int exfat_parse_param(struct fs_context *fc, struct fs_parameter *param)
 			return -EINVAL;
 		opts->time_offset = result.int_32;
 		break;
+	case Opt_utf8:
+	case Opt_debug:
+	case Opt_namecase:
+	case Opt_codepage:
+		break;
 	default:
 		return -EINVAL;
 	}
-- 
2.17.1