isofs: joliet: Fix iocharset=utf8 mount option

Currently iocharset=utf8 mount option is broken. To use UTF-8 as iocharset,
it is required to use utf8 mount option.

Fix iocharset=utf8 mount option to use be equivalent to the utf8 mount
option.

If UTF-8 as iocharset is used then s_nls_iocharset is set to NULL. So
simplify code around, remove s_utf8 field as to distinguish between UTF-8
and non-UTF-8 it is needed just to check if s_nls_iocharset is set to NULL
or not.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Pali Rohár <[e-mail]>
Signed-off-by: Jan Kara <[e-mail]>

fs/isofs/inode.c

···
 	unsigned int overriderockperm:1;
 	unsigned int uid_set:1;
 	unsigned int gid_set:1;
-	unsigned int utf8:1;
 	unsigned char map;
 	unsigned char check;
 	unsigned int blocksize;
···
 	popt->gid = GLOBAL_ROOT_GID;
 	popt->uid = GLOBAL_ROOT_UID;
 	popt->iocharset = NULL;
-	popt->utf8 = 0;
 	popt->overriderockperm = 0;
 	popt->session=-1;
 	popt->sbsector=-1;
···
 		case Opt_cruft:
 			popt->cruft = 1;
 			break;
-		case Opt_utf8:
-			popt->utf8 = 1;
-			break;
 #ifdef CONFIG_JOLIET
+		case Opt_utf8:
+			kfree(popt->iocharset);
+			popt->iocharset = kstrdup("utf8", GFP_KERNEL);
+			if (!popt->iocharset)
+				return 0;
+			break;
 		case Opt_iocharset:
 			kfree(popt->iocharset);
 			popt->iocharset = match_strdup(&args[0]);
···
 	if (sbi->s_nocompress)		seq_puts(m, ",nocompress");
 	if (sbi->s_overriderockperm)	seq_puts(m, ",overriderockperm");
 	if (sbi->s_showassoc)		seq_puts(m, ",showassoc");
-	if (sbi->s_utf8)		seq_puts(m, ",utf8");
 
 	if (sbi->s_check)		seq_printf(m, ",check=%c", sbi->s_check);
 	if (sbi->s_mapping)		seq_printf(m, ",map=%c", sbi->s_mapping);
···
 		seq_printf(m, ",fmode=%o", sbi->s_fmode);
 
 #ifdef CONFIG_JOLIET
-	if (sbi->s_nls_iocharset &&
-	    strcmp(sbi->s_nls_iocharset->charset, CONFIG_NLS_DEFAULT) != 0)
+	if (sbi->s_nls_iocharset)
 		seq_printf(m, ",iocharset=%s", sbi->s_nls_iocharset->charset);
+	else
+		seq_puts(m, ",iocharset=utf8");
 #endif
 	return 0;
 }
···
 	sbi->s_nls_iocharset = NULL;
 
 #ifdef CONFIG_JOLIET
-	if (joliet_level && opt.utf8 == 0) {
+	if (joliet_level) {
 		char *p = opt.iocharset ? opt.iocharset : CONFIG_NLS_DEFAULT;
-		sbi->s_nls_iocharset = load_nls(p);
-		if (! sbi->s_nls_iocharset) {
-			/* Fail only if explicit charset specified */
-			if (opt.iocharset)
+		if (strcmp(p, "utf8") != 0) {
+			sbi->s_nls_iocharset = opt.iocharset ?
+				load_nls(opt.iocharset) : load_nls_default();
+			if (!sbi->s_nls_iocharset)
 				goto out_freesbi;
-			sbi->s_nls_iocharset = load_nls_default();
 		}
 	}
 #endif
···
 	sbi->s_gid = opt.gid;
 	sbi->s_uid_set = opt.uid_set;
 	sbi->s_gid_set = opt.gid_set;
-	sbi->s_utf8 = opt.utf8;
 	sbi->s_nocompress = opt.nocompress;
 	sbi->s_overriderockperm = opt.overriderockperm;
 	/*

fs/isofs/isofs.h

···
 	unsigned char s_session;
 	unsigned int  s_high_sierra:1;
 	unsigned int  s_rock:2;
-	unsigned int  s_utf8:1;
 	unsigned int  s_cruft:1; /* Broken disks with high byte of length
 				  * containing junk */
 	unsigned int  s_nocompress:1;

fs/isofs/joliet.c

···
 int
 get_joliet_filename(struct iso_directory_record * de, unsigned char *outname, struct inode * inode)
 {
-	unsigned char utf8;
 	struct nls_table *nls;
 	unsigned char len = 0;
 
-	utf8 = ISOFS_SB(inode->i_sb)->s_utf8;
 	nls = ISOFS_SB(inode->i_sb)->s_nls_iocharset;
 
-	if (utf8) {
+	if (!nls) {
 		len = utf16s_to_utf8s((const wchar_t *) de->name,
 				de->name_len[0] >> 1, UTF16_BIG_ENDIAN,
 				outname, PAGE_SIZE);