ext4: factor out ext4_encoding_init()

Factor out ext4_encoding_init(). No functional change.
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220916141527.1012715-8-yanaijie@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/super.c

@@ -4492,6 +4492,54 @@ static int ext4_inode_info_init(struct super_block *sb,
 	return 0;
 }
 
+#if IS_ENABLED(CONFIG_UNICODE)
+static int ext4_encoding_init(struct super_block *sb, struct ext4_super_block *es)
+{
+	const struct ext4_sb_encodings *encoding_info;
+	struct unicode_map *encoding;
+	__u16 encoding_flags = le16_to_cpu(es->s_encoding_flags);
+
+	if (!ext4_has_feature_casefold(sb) || sb->s_encoding)
+		return 0;
+
+	encoding_info = ext4_sb_read_encoding(es);
+	if (!encoding_info) {
+		ext4_msg(sb, KERN_ERR,
+			"Encoding requested by superblock is unknown");
+		return -EINVAL;
+	}
+
+	encoding = utf8_load(encoding_info->version);
+	if (IS_ERR(encoding)) {
+		ext4_msg(sb, KERN_ERR,
+			"can't mount with superblock charset: %s-%u.%u.%u "
+			"not supported by the kernel. flags: 0x%x.",
+			encoding_info->name,
+			unicode_major(encoding_info->version),
+			unicode_minor(encoding_info->version),
+			unicode_rev(encoding_info->version),
+			encoding_flags);
+		return -EINVAL;
+	}
+	ext4_msg(sb, KERN_INFO,"Using encoding defined by superblock: "
+		"%s-%u.%u.%u with flags 0x%hx", encoding_info->name,
+		unicode_major(encoding_info->version),
+		unicode_minor(encoding_info->version),
+		unicode_rev(encoding_info->version),
+		encoding_flags);
+
+	sb->s_encoding = encoding;
+	sb->s_encoding_flags = encoding_flags;
+
+	return 0;
+}
+#else
+static inline int ext4_encoding_init(struct super_block *sb, struct ext4_super_block *es)
+{
+	return 0;
+}
+#endif
+
 static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
 {
 	struct buffer_head *bh, **group_desc;
@@ -4649,42 +4697,8 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
 
 	ext4_apply_options(fc, sb);
 
-#if IS_ENABLED(CONFIG_UNICODE)
-	if (ext4_has_feature_casefold(sb) && !sb->s_encoding) {
-		const struct ext4_sb_encodings *encoding_info;
-		struct unicode_map *encoding;
-		__u16 encoding_flags = le16_to_cpu(es->s_encoding_flags);
-
-		encoding_info = ext4_sb_read_encoding(es);
-		if (!encoding_info) {
-			ext4_msg(sb, KERN_ERR,
-				 "Encoding requested by superblock is unknown");
-			goto failed_mount;
-		}
-
-		encoding = utf8_load(encoding_info->version);
-		if (IS_ERR(encoding)) {
-			ext4_msg(sb, KERN_ERR,
-				 "can't mount with superblock charset: %s-%u.%u.%u "
-				 "not supported by the kernel. flags: 0x%x.",
-				 encoding_info->name,
-				 unicode_major(encoding_info->version),
-				 unicode_minor(encoding_info->version),
-				 unicode_rev(encoding_info->version),
-				 encoding_flags);
-			goto failed_mount;
-		}
-		ext4_msg(sb, KERN_INFO,"Using encoding defined by superblock: "
-			 "%s-%u.%u.%u with flags 0x%hx", encoding_info->name,
-			 unicode_major(encoding_info->version),
-			 unicode_minor(encoding_info->version),
-			 unicode_rev(encoding_info->version),
-			 encoding_flags);
-
-		sb->s_encoding = encoding;
-		sb->s_encoding_flags = encoding_flags;
-	}
-#endif
+	if (ext4_encoding_init(sb, es))
+		goto failed_mount;
 
 	if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA) {
 		printk_once(KERN_WARNING "EXT4-fs: Warning: mounting with data=journal disables delayed allocation, dioread_nolock, O_DIRECT and fast_commit support!\n");