ext4: print ext4 mount option data_err=abort correctly

If data_err=abort option is specified for an ext3/ext4 mount,
/proc/mounts does show it as "(null)". This is caused by token2str()
returning NULL for Opt_data_err_abort (due to its pattern containing
'=').
Signed-off-by: Ales Novak <alnovak@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/super.c

@@ -1422,9 +1422,9 @@ static const struct mount_opts {
 	{Opt_err_ro, EXT4_MOUNT_ERRORS_RO, MOPT_SET | MOPT_CLEAR_ERR},
 	{Opt_err_cont, EXT4_MOUNT_ERRORS_CONT, MOPT_SET | MOPT_CLEAR_ERR},
 	{Opt_data_err_abort, EXT4_MOUNT_DATA_ERR_ABORT,
-	 MOPT_NO_EXT2 | MOPT_SET},
+	 MOPT_NO_EXT2},
 	{Opt_data_err_ignore, EXT4_MOUNT_DATA_ERR_ABORT,
-	 MOPT_NO_EXT2 | MOPT_CLEAR},
+	 MOPT_NO_EXT2},
 	{Opt_barrier, EXT4_MOUNT_BARRIER, MOPT_SET},
 	{Opt_nobarrier, EXT4_MOUNT_BARRIER, MOPT_CLEAR},
 	{Opt_noauto_da_alloc, EXT4_MOUNT_NO_AUTO_DA_ALLOC, MOPT_SET},
@@ -1702,6 +1702,10 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
 		ext4_msg(sb, KERN_INFO, "dax option not supported");
 		return -1;
 #endif
+	} else if (token == Opt_data_err_abort) {
+		sbi->s_mount_opt |= m->mount_opt;
+	} else if (token == Opt_data_err_ignore) {
+		sbi->s_mount_opt &= ~m->mount_opt;
 	} else {
 		if (!args->from)
 			arg = 1;
@@ -1911,6 +1915,8 @@ static int _ext4_show_options(struct seq_file *seq, struct super_block *sb,
 		SEQ_OPTS_PRINT("init_itable=%u", sbi->s_li_wait_mult);
 	if (nodefs || sbi->s_max_dir_size_kb)
 		SEQ_OPTS_PRINT("max_dir_size_kb=%u", sbi->s_max_dir_size_kb);
+	if (test_opt(sb, DATA_ERR_ABORT))
+		SEQ_OPTS_PUTS("data_err=abort");
 
 	ext4_show_quota_options(seq, sb);
 	return 0;