bcachefs: Fix error in parsing of mount options

When parsing the mount options duplicate the given options. This is
required as the options are parsed twice and strsep is used in parsing.
The options will be modified into a possibly invalid options set for the
second round of parsing if the options are not duplicated before
parsing.
Signed-off-by: Dan Robertson <dan@dlrobertson.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/opts.c

@@ -315,11 +315,20 @@ int bch2_opts_check_may_set(struct bch_fs *c)
 int bch2_parse_mount_opts(struct bch_fs *c, struct bch_opts *opts,
 			  char *options)
 {
+	char *copied_opts, *copied_opts_start;
 	char *opt, *name, *val;
 	int ret, id;
 	u64 v;
 
-	while ((opt = strsep(&options, ",")) != NULL) {
+	if (!options)
+		return 0;
+
+	copied_opts = kstrdup(options, GFP_KERNEL);
+	if (!copied_opts)
+		return -1;
+	copied_opts_start = copied_opts;
+
+	while ((opt = strsep(&copied_opts, ",")) != NULL) {
 		name	= strsep(&opt, "=");
 		val	= opt;
 
@@ -363,16 +372,24 @@ int bch2_parse_mount_opts(struct bch_fs *c, struct bch_opts *opts,
 		bch2_opt_set_by_id(opts, id, v);
 	}
 
-	return 0;
+	ret = 0;
+	goto out;
+
 bad_opt:
 	pr_err("Bad mount option %s", name);
-	return -1;
+	ret = -1;
+	goto out;
 bad_val:
 	pr_err("Invalid value %s for mount option %s", val, name);
-	return -1;
+	ret = -1;
+	goto out;
 no_val:
 	pr_err("Mount option %s requires a value", name);
-	return -1;
+	ret = -1;
+	goto out;
+out:
+	kfree(copied_opts_start);
+	return ret;
 }
 
 /* io opts: */